Earticle

본 연구는 「산지관리법」에 따라 복구준공 검사일로부터 3년 미만인 산림지역에 개설된 지중 송전시설 주변 산림지역의 복구공사 현장의 효율적인 모니터링을 위한 연구로 작업 인원을 Type A, B, C로 구분하여 시간연구방법을 통해 동시작업시간과 작업여유시간을 파악하였다. 또 한 현장점검을 위한 요소작업을 ‘GNSS 경계 측량’, ‘드론 촬영’,‘ 현장 점검’ 3개 작업으로 구분 하였으며, 11개의 하위 항목으로 구분하여 측정하였다. 연구 결과 동시작업시간과 작업여유시간 은 Type A에서 2.47시간과 2.71시간으로 측정되었으며, Type B는 2.47시간과 0.46시간 Type C는 1.41시간과 1.06시간으로 측정되어 작업여유시간을 고려한 가장 효율적인 작업은 Type B로 사료 된다. 이를 2024년 엔지니어링사업대가 기준에 따라 산출한 현장점검에 소요되는 비용은 1,878,226원으로 나타났다. 본 연구는 체계적인 모니터링 기법의 개발과 송전시설의 산지관리정 책 및 재해예방 기술 고도화를 위한 기초자료로 제공하기 위해 수행되었다.

This study was conducted to derive efficient field inspection work for restoration sites around the underground transmission facilities established in forest areas less than 3 years from the completion date under the Mountainous District Management Act. The field inspection work was divided into three types according to the number of workers, and the work time and work slack time were identified through the time study method. In addition, the element work for on-site inspection was divided into three tasks: ‘GNSS boundary surveying’, ‘drone shooting’, and ‘field monitoring’, and was measured by classifying it into 11 sub-items. As a result of the study, the net work time and allowance time were estimated as 2.47 hours and 2.71 hours for 2 people in 1 team, 2.47 hours and 0.46 hours for 3 people in 1 team, and 1.41 hours and 1.06 hours for 4 people in 1 team. Therefore, it is considered that the most efficient work is Type B. The cost of field inspection work calculated based on the 2024 Engineering Business Unit standard was 1,878,226 Korean won. This study was conducted to provide basic data for developing systematic monitoring techniques and advancing mountain management policies and disaster prevention technologies for power transmission facilities.

The objectives of this study were to investigate the degrees of emotional labor, the effects to organizational effectiveness and the significant factors influencing organizational effectiveness in radiation therapy professional. The subjects of this study were the radiation therapists working at the hospital in Seoul and Gyungi. The self-reported questionnaires were administered to 205 radiation therapists and the data were analyzed with SPSS 19.0 package. The level of emotional labor of single or female subjects were revealed higher than married or male. The professionalism of job has significant correlation with emotional labor. Significant explanatory variables of the degrees of emotional labor included organization culture, distress and self-leadership. These three variables demonstrated the explanatory power of 13.9% of the emotional labor. Based on the findings, emotional labor of radiation therapist was correlated with occupational professionalism. These results suggest that the intervention program intervening emotional labor should be continued to develop in order to improve the effective self-leadership, organization culture and distress factor.

본 연구의 목적은 높이맵 기반의 액체 시뮬레이션을 이용하여 인간 친화적으로 표현하기 위한 감성 컨텐츠 제작 에 있다. 액체를 인간 친화적으로 표현하는 기존 연구들은 액체 표면을 표현하는데 몇 가지 문제점이 있다. 이러한 문 제를 해결하기 위해 본 연구는 액체의 광학적 특징을 이용한 새로운 액체의 카툰 렌더링 기법을 제안한다. 본 연구 에서 제안하는 액체의 카툰 렌더링은 반사와 굴절을 독립적으로 표현한 채색 단계와 액체의 경계선과 파형선을 표현 하는 선화 단계를 거쳐 표현된다. 그 결과 인간 친화적으로 표현된 액체의 표면을 실시간으로 감성 컨텐츠로 제작할 수 있다.

The purpose of this study is the development of human friendly emotion contents using heightfield based liquid simulation. The previous studies have some problems representing human friendly emotional content. To solve these problems, this study suggests the cartoon rendering using the optical characteristic of liquid. The proposed method represent liquid simulation through cartoon shading using reflection and refraction of liquid and line drawing using boundary and wave lines. This approach can produce the human friendlily emotional contents represented the surface of liquid in realtime

본 연구는 액체의 광학, 역학적인 특징에 대해 알아보고 컴퓨터 그래픽스에서 액체를 구현하는 방식과 함께 높이맵을 기반으로 한 액체표현을 목표로 하고 있다. 빛은 액체와 만났을 때 반사, 굴절, 흡수 현상이 일어난다. 액체는 불순물이 많고 점성이 높을수록 반사율이 높으며 액체의 굴절률은 스넬의 법칙(snell's law)을 이용하여 구할 수 있다. 역학적으로 액체는 임의의 크기로 전단응력을 받을 때, 연속적으로 변형하는 물질이라 정의 내릴 수 있으며 액체에 적용되는 기본적인 운동법칙들은 고체에 적용하는 운동법칙과 접근방법에서는 유사하다. 본 연구에서 환경 맵과 프레넬의 법칙을 이용한 반사 굴절을 구현하였으며 부드러운 액체의 표면을 생성하고 sin, cos곡선을 이용하여 유체의 높낮이를 자연스럽게 구현하였다.

The goal of this study is to represent heightfield-map based liquid simulation. To do this, we examine the optical and dynamic features of liquid. When a light intersect a liquid, it is reflected and refracted. If a liquid has some impurities on it and high viscosity, the angle of reflection is large. The ratio of a liquid's refraction can calculate from snell's law. The definition of liquid is the continuous deformed material when it pressed some shear stress. The fundamentals of liquid is similar to the characteristics of solid. In this study, we develop the reflection and refraction of the liquid using fresnel equation. To visualize the liquid, we utilize an environment map that represent the surrounding scene and a heightfield-map using trigonometrical functions.

The present study has been designed to theoretically predict the transient rheological behavior of concentrated xanthan gum systems in start-up shear flow fields using the Wagner constitutive equation. Using an Advanced Rheometric Expansion System (ARES), a number of constant shear rates were suddenly imposed to aqueous xanthan gum solutions with different concentrations and then the resultant shear stress responses were detected with time. The linear and nonlinear stress relaxation moduli at various deformation magnitudes were also measured to determine the damping function. The linear relaxation modulus was characterized by a power-law expression to determine the memory function and a time-strain separability of the nonlinear relaxation moduli was employed to predict the nonlinear response. The experimentally obtained damping function was compared with the fitted results calculated from the two mathematical forms of the Wagner and Soskey-Winter equations in order to examine the effect of damping function on the predictive performance of the Wagner model. The overall applicability of the Wagner model for predicting the whole procedures of a transient rheological behavior at start-up of steady shear flow was discussed in depth. The main findings obtained from this study are summarized as follows : (1) The Wagner model has a predictive ability to qualitatively express the whole procedures of a transient rheological behavior of concentrated xanthan gum solutions for all shear rates imposed, regardless of selecting a damping function. (2) The values of the maximum reduced stress predicted by the Wagner model employing the Wagner damping function exhibit an almost equal magnitude, irrespective of the shear rates imposed, whereas those predicted by the Wagner model employing the Soskey-Winter damping function are gradually decreased with an increase in imposed shear rate. (3) For all shear rates applied, the Wagner model having the Wagner damping function has a fairly good ability to predict the time at which the maximum stress occurs, tmax, while the Wagner model having the Soskey-Winter damping function predicts a much faster value of tmax. (4) The Wagner model using both of the Wagner and Soskey-Winter damping functions has a weakness with respect to predicting a stress decay which always show a slower decrement than does the predicted results by the Wagner model using the two different forms of a damping function. (5) The Wagner model adopting the Wagner damping function exhibits a superior performance to the Wagner model adopting the Soskey-Winter damping function for predicting the whole steps of a transient rheological behavior.

We fabricated high transmission and high scattering poly(ethylene-co-vinyl acetate)(EVA) films embedding $SiO_2$ nanoparticles to improve outcoupling efficiency in organic display. The 800nm diameter $SiO_2$ nanoparticles aggregated and formed $1.56{\mu}m$ (with ${\pm}0.853{\mu}m$ standard deviation) diameter microparticles in EVA. The total transmission of scattering film was 83.3% on Polyethylene terephthalate(PET), which was higher than reference 82.8% PET substrate. The diffuse transmission and haze of the $SiO_2$ embedded EVA film were 76.1% and 91.4%, respectively. The optimized condition was 1:1 weight ratio of $SiO_2$ nanoparticles to EVA in Tetrahydrofuran(THF) solution. When the ratio of $SiO_2$ was larger than 1, the total transmission decreased by the increase in backscattering of light due to high scattering. With the optimized condition, we could succeed to fabricate a large scale film(35m in length) with a roll-to-roll process.

The present study has been designed to describe the nonlinear viscoelastic behavior of concentrated polymer systems in large amplitude oscillatory shear (LAOS) flow fields using a time-strain separable K-BKZ constitutive equation (i.e., Wagner model). Using an Advanced Rheometric Expansion System (ARES), the dynamic viscoelastic behavior of aqueous poly(ethylene oxide) (PEO) solutions with various molecular weights and different concentrations has been investigated with a various combination of several fixed strain amplitudes and constant angular frequencies. The linear dynamic data (storage modulus and loss modulus) over a wide range of angular frequencies were obtained to determine the relaxation spectrum parameters and the stress relaxation moduli at various deformation magnitudes were measured to determine the damping function. The effects of the number of relaxation spectrum parameters and damping functions on the prediction results of the Wagner model were examined in depth. The nonlinear viscoelastic functions were analyzed by the aid of 3D plots and predicted over a wide range of strain amplitudes to evaluate the overall predictability of the Wagner model. The main findings obtained from this study are summarized as follows : (1) The Lissajous patterns predicted by the Wagner model are in good coincidence with the experimentally obtained stress-strain rate hysteresis loops both in linear and nonlinear viscoelastic regions and are independent of the number of relaxation spectrum parameters used in the calculation of memory function. (2) The effect of damping function on the predictive ability of the Wagner model is more sensitive than that of memory function. When the damping function is smaller than that of the experimental data, the stress amplitude predicted by the Wagner model also becomes smaller. (3) The Wagner model predictions are closely coincident with the experimental results in the linear viscoelastic region. As the strain amplitude is increased, the predicted nonlinear viscoelastic functions are somewhat larger than that of the experimental data. Nevertheless, all trends of the nonlinear viscoelastic behavior are in good agreement with the experimental results in a qualitative sense. (4) The Wagner model predicts the first harmonic loss modulus more exactly than the first harmonic storage modulus. As the strain amplitude is increased, the first harmonic storage modulus is somewhat overpredicted. The third and fifth harmonic storage and loss moduli exhibit an overshoot or an undershoot at large strain amplitudes. This constitutive equation has an ability to qualitatively describe well such dramatic behavioral changes.

The present study has been performed to quantitatively characterize the nonlinear rheological behavior of concentrated xanthan gum systems in large amplitude oscillatory shear (LAOS) flow fields by means of the methodology of Fourier transform (FT) rheology. Using an Advanced Rheometric Expansion System (ARES), the dynamic viscoelastic behavior of aqueous xanthan gum solutions with different concentrations has been experimentally investigated in LAOS flow conditions with a various combination of several fixed strain amplitudes and constant angular frequencies. The nonlinear viscoelastic functions were derived from the Fourier spectra of stress responses, and then the fundamental and higher harmonic contributions were calculated from discrete Fourier transform (DFT). The nonlinear viscoelastic behavior was interpreted by displaying 3D plots, and then the effects of strain amplitude and angular frequency on the nonlinear behavior were discussed in depth. A comparison of the experimentally obtained stress response with the stress waves calculated from higher harmonic nonlinear viscoelastic functions was made to clarify the role of higher harmonic contributions. The main findings obtained from this study are summarized as follows : (1) When the strain amplitude becomes larger than a critical value of 50%, the higher nonlinear viscoelastic functions must be considered to explain the nonlinear viscoelastic behavior. However, the fundamental stress amplitude is dominantly larger than those of higher harmonics. (2) As the strain amplitude is increased, the fundamental stress amplitude is steeply increased within the linear viscoelastic region beyond which followed by an approximately constant magnitude at large deformations. This strain dependence may be explained as a distinction between linear and nonlinear viscoelastic behavior. (3) When the strain amplitude exceeds a critical value of 50%, the higher stress amplitudes are sharply increased with an increase in strain amplitude at large deformations, indicating that the higher stress harmonics exert an influence on the nonlinear viscoelastic behavior. (4) In order to interpret the complicated nonlinear viscoelastic behavior occurring at large deformations, the fundamental terms as well as the higher harmonics of phase angles defined at the odd terms should be deliberated for a quantitatively advanced analysis. (5) An overall shape of the experimentally obtained stress response is strongly affected by the higher harmonic contributions. As the angular frequency is decreased, a more distorted and a sharper stress waveform is observed at LAOS deformations. (6) A distorted stress waveform is qualitatively inclined to the left side with respect to a sinusoidal curve. In order to explain the nonlinear viscoelastic behavior of concentrated xanthan gum systems in LAOS flow fields, the nonlinear viscoelastic functions from the first to at least seventh harmonics should be considered for an accurate analysis.

The present study has been designed to predict the nonlinear viscoelastic behavior of concentrated polymer systems in large amplitude oscillatory shear (LAOS) flow fields by means of the Doi-Edwards constitutive equation. Using an Advanced Rheometric Expansion System (ARES), the dynamic viscoelastic behavior of aqueous poly (ethylene oxide) (PEO) solutions with various molecular weights and different concentrations has been investigated with a various combination of several fixed strain amplitudes and constant angular frequencies. The linear dynamic data (storage modulus and loss modulus) over a wide range of angular frequencies were also obtained to determine the relaxation spectrum parameters. The experimentally obtained Lissajous patterns (stress-strain rate hysteresis loops) were compared with the Doi-Edwards model predictions over a wide range of strain amplitudes and angular frequencies for all polymer solutions prepared in this work. The nonlinear viscoelastic functions were analyzed by the aid of 3D plots and predicted over a wide range of strain amplitudes to evaluate the overall predictability of the Doi-Edwards model. The main findings obtained from this study are summarized as follows : (1) The Lissajous patterns predicted by the Doi-Edwards model represent a good agreement with the experimentally obtained stress-strain rate hysteresis loops both in linear and nonlinear viscoelastic regions. (2) The predictions of the Doi-Edwards model are closely coincident with the experimental results in the linear viscoelastic region. As the strain amplitude is increased, the predicted nonlinear viscoelastic functions are somewhat larger than that of the experimental data. Nevertheless, all trends of the nonlinear viscoelastic behavior are qualitatively in good agreement with the experimental results. (3) The Doi-Edwards model gives a very good prediction for the first harmonic storage modulus and loss modulus up to the nonlinear viscoelastic region. The third and fifth harmonic storage and loss moduli exhibit an overshoot or an undershoot at large strain amplitudes. This constitutive equation can describe well such excessive behavioral changes in a qualitative sense. (4) The Doi-Edwards model has a slightly better ability than the Wagner model to predict the LAOS flow behavior of concentrated polymer systems.

The objective of the present study is to systematically characterize the nonlinear viscoelastic behavior of concentrated polymer systems in large amplitude oscillatory shear (LAOS) flow fields by means of discrete Fourier transform (DFT) analysis. Using an Advanced Rheometric Expansion System (ARES), the dynamic viscoelastic behavior of aqueous poly(ethylene oxide) (PEO) solutions with various molecular weights and different concentrations has been investigated with several fixed strain amplitudes and constant angular frequencies. The nonlinear viscoelastic functions and the degree of nonlinearity were derived from the Fourier spectra of stress responses, and then the nonlinear behavior was interpreted by the use of 3D and contour plots, respectively. The effects of strain amplitude and angular frequency on the nonlinear viscoelastic behavior were nextly discussed in depth. In addition, the strain limits of linear viscoelastic response were determined from the ratio of harmonic contributions, and then the validity of Pipkin diagram with regard to characteristic time was evaluated for all PEO solutions. The main findings obtained from this study are summarized as follows: (1) At small strain amplitudes, the influence of the first harmonic contribution is dominant. As the strain amplitude becomes larger, however, the effect of higher odd harmonic contributions is increased, resulting in an occurrence of a nonlinear viscoelastic behavior. (2) The degree of nonlinearity is increased with an increase in strain amplitude. This is also increased with increasing angular frequency until reaching the maximum value at a certain angular frequency and then decreased with a further increase in angular frequency. (3) The Pipkin diagram with regard to characteristic time is a very effective method to explore the nonlinear regime of viscoelastic polymer liquids in LAOS deformations.

The objective of the present study is to phenomenologically characterize the nonlinear rheological behavior of concentrated xanthan gum systems in large amplitude oscillatory shear (LAOS) flow fields by means of stress waveform and Lissajous pattern analysis. Using an Advanced Rheometric Expansion System (ARES), the dynamic viscoelastic behavior of aqueous xanthan gum solutions with different concentrations has been experimentally investigated in LAOS flow conditions with a various combination of several fixed strain amplitudes and constant angular frequencies. The main findings obtained from this study are summarized as follows: (1) When a sinusoidal deformation with large strain amplitude is applied, a distorted and nonsinusoidal but symmetrical stress response waveform is observed with time. (2) A saw-tooth shaped stress signal detected at large strain amplitudes may arise from a unique microstructure of xanthan polymer chains. A small peak of stress wave appearing at the position of maximum and minimum stress represents a nonlinear viscous nature of concentrated xanthan gum systems in LAOS flow fields. (3) As an increase in polymer concentration, the shape of stress wave becomes sharper and more distorted. This trend may be explained by an increase in structural density. (4) As a decrease in angular frequency, the stress wave exhibits a more distorted shape and both of the maximum and minimum peaks of a saw-tooth shaped stress response becomes more dominant. (5) At relatively small strain amplitudes, the Lissajous patterns (stress versus strain rate loops) show an elliptical form and their normalized ones are coincident with each other. When larger strain amplitudes are applied, however, the Lissajous patterns are noticeably nonelliptical, and moreover, as the strain amplitude is further increased, the tips of loops become more pointed with exhibiting a characteristic "S" shape.

Using an Advanced Rheometric Expansion System (ARES), the dynamic viscoelastic behavior of aqueous poly(ethylene oxide) (PEO) solutions with various molecular weights and different concentrations has been investigated in large amplitude oscillatory shear (LAOS) flow fields over a wide range of strain amplitudes. In order to predict the nonlinear viscoelastic behavior of polymer liquids in strain-sweep experiments, a new analysis method including a simple empirical model was proposed and then its validity was thoroughly evaluated in this study. The results have shown that the suggested model is significant in 95% confidence level and predicts exactly the nonlinear viscoelastic behavior of polymer liquids over a whole range of strain amplitudes tested. The strain limits of linear viscoelastic response and nonlinear behavior indices were determined using this model to estimate the LAOS flow behavior in strain-sweep experiments. The master curves of strain limits and nonlinear behavior indices can be obtained by representing these data against the product of angular frequency by characteristic time. The LAOS flow behavior of polymer systems with various molecular weights and different concentrations can well be predicted from these master curves.

The objective of this study is to systematically investigate the relationships between steady flow functions and transient flow functions for viscoelastic polymer liquids. Using a strain-controlled rheometer (Advanced Rheometric Expansion System (ARES)), the steady shear flow properties and the transient shear flow properties of concentrated poly(ethylene oxide) (PEO) solutions have been measured over a wide range of shear rates and times. The validity of the three forms of the Gleissle mirror relations was examined by comparing them with the experimentally obtained results. In addition, the effect of nonlinearity on the applicability of these Gleissle mirror relations was discussed from a theoretical view-point by introducing the concept of a nonlinear strain measure. The main findings obtained from this study can be summarized as follows: (1) A nonlinear strain measure is decreased with an increase in strain magnitude, after reaching the maximum value at small strain range. This behavior is quite different from the theoretical prediction to satisfy the conditions of the Gleissle mirror relations. (2) The first mirror relation describing the equivalence between steady shear flow viscosity and shear stress growth coefficient is valid over a wide range of shear rates and is hardly affected by the nonlinearity of polymer solutions. (3) The second mirror relation expressing the equivalence between first normal stress coefficient and first normal stress growth coefficient is also applicable over a wide range of shear rates. This relation is, however, significantly influenced by the degree of nonlinearity (i.e., shape of a nonlinear strain measure) of polymer solutions. (4) The third mirror relation can be regarded as a very useful empirical model to predict the first normal stress coefficient from steady shear flow viscosity data, provided that an appropriate value of a shift factor is given.

두경부암 환자의 헤드 홀더를 사용하는 경우 모의 치료 시 환자는 테이블 위에 위치하지만, 방사선 치료를 시행하는 경우 헤드 홀더를 치료 테이블에 걸쳐서 사용하기 때문에 체중 및 여러 가지 요소로 인한 기하학적 불일치로 상, 하, 좌, 우 및 처짐의 현상이 발생할 수 있다. 이러한 환자 Set-Up의 재현성의 불일치를 개선하기 위해 두경부암 전용 헤드 홀더를 자체 고안하여 제작 및 개발하여 유용성을 평가하였다. Alderson Rando Phantom을 이용하여 전산화단층촬영장치(High Advantage, GE, U.S.A)를 통해 이미지를 획득하였고, 광자선 4MV 세기변조 방사선치료(IMRT) 방식을 적용하여 최적화된 치료 계획을 실시하였다. 선형가속기(21EX, Varian, U.S.A)를 이용하여 모의 치료와 동일한 상태에서 환자를 set-up한 후 에 치료기에 장착된 CBCT를 이용하여 각각의 무게(0,15,30Kg)의 차이를 통해 교정 전, 후 X, Y, Z축의 오차를 5회 반복 측정한 결과는 다음과 같다. 0Kg에서 $0.4{\pm}0.8mm$, $0.8{\pm}0.4mm$, 0mm으로 나타났고, 교정 후에는 $0.2{\pm}0.8mm$, $0.4{\pm}0.5mm$, 0으로 나타났다. 15Kg에서 교정 전,후 오차는 $0.2{\pm}0.8mm$, $1.2{\pm}0.4mm$, $2.2{\pm}0.4mm$와 $0.2{\pm}0.4mm$, $0.4{\pm}0.5mm$, $0.4{\pm}0.5mm$로 나타났다. 30Kg에서 교정 전,후 오차는 $0.8{\pm}0.4mm$, $2.4{\pm}0.5mm$, $4.4{\pm}0.8mm$와 $0.6{\pm}0.54mm$, $1{\pm}0mm$, $0.6{\pm}0.5mm$로 나타났다. 각각의 교정 전,후의 통계적으로 분석한 결과 15Kg인 경우 Z축에서 p<0.034, 30Kg인 경우 Y, Z축에서 p<0.038, p<0.041 로 유의한 결과를 나타냈다. 두경부암 전용 방향 조절 장치 헤드 홀더가 환자의 set-up오차를 줄여주는 역할을 해주는 것으로 나타났다. 또한 오차를 줄여줌으로써 환자의 재현성이 향상되어 보다 정밀하고 정확한 방사선 치료를 구현할 수 있을 것으로 사료된다.

In case of all patients who receive radiation therapy, a treatment plan is established and all steps of treatment are planned in the same geometrical condition. In case of head and neck cancer patients who undergo simulated treatment through computed tomography (CT), patients are fixed onto a table for planning, but laid on the top of the treatment table in the radiation therapy room. This study excogitated and fabricated an adjustable holder for head and neck cancer patients to fix patient's position and geometrical discrepancies when performing radiation therapy on head and neck cancer patients, and compared the error before and after adjusting the position of patients due to difference in weight to evaluate the correlation between patients' weight and range of error. Computed tomography system(High Advantage, GE, USA) is used for phantom to maintain the supine position to acquire the images of the therapy site for IMRT. IMRT 4MV X-rays was used by applying the LINAC(21EX, Varian, U.S.A). Treatment planning system (Pinnacle, ver. 9.1h, Philips, Madison, USA) was used. The setup accuracy was compared with each measurement was repeated five times for each weight (0, 15, and 30Kg) and CBCT was performed 30 times to find the mean and standard deviation of errors before and after the adjustment of each weight. SPSS ver.19.0(SPSS Inc., Chicago, IL,USA) statistics program was used to perform the Wilcoxon Rank test for significance evaluation and the Spearman analysis was used as the tool to analyze the significance evaluation of the correlation of weight. As a result of measuring the error values from CBCT before and after adjusting the position due to the weight difference, X,Y,Z axis was $0.4{\pm}0.8mm$, $0.8{\pm}0.4mm$, 0 for 0Kg before the adjustment. In 15Kg CBCT before and after adjusting the position due to the weight difference, X,Y,Z axis was $0.2{\pm}0.8mm$, $1.2{\pm}0.4mm$, $2.0{\pm}0.4mm$. After adjusting position was X,Y,Z axis was $0.2{\pm}0.4mm$, $0.4{\pm}0.5mm$, $0.4{\pm}0.5mm$. In 30Kg CBCT before and after adjusting the position due to the weight difference, X,Y,Z axis was $0.8{\pm}0.4mm$, $2.4{\pm}0.5mm$, $4.4{\pm}0.8mm$. After adjusting position was X,Y,Z axis was $0.6{\pm}0.5mm$, $1.0{\pm}0mm$, $0.6{\pm}0.5mm$. When the holder for the head and neck cancer was used to adjust the ab.0ove error value, the error values from CBCT were $0.2{\pm}0.8mm$ for the X axis, $0.40{\pm}0.54mm$ for Y axis, and 0 for Z axis. As a result of statistically analyzing each value before and after the adjustment the value was significant with p<0.034 at the Z axis with 15Kg of weight and with p<0.038 and p<0.041 at the Y and Z axes respectively with 30Kg of weight. There was a significant difference with p<0.008 when the analysis was performed through Kruscal-Wallis in terms of the difference in the adjusted values of the three weight groups. As it could reduce the errors, patients' reproduction could be improved for more precise and accurate radiation therapy. Development of an adjustable device for head and neck cancer patients is significant because it improves the reproduction of existing equipment by reducing the errors in patients' position.

목 적 : 토모테라피(Tomotherapy)와 선형가속기(Linac)를 이용한 세기조절방사선치료(IMRT) 시 환자의 정확한 위치잡이를 위해 매일 시행되는 MVCT와 CBCT의 imaging dose를 비교 평가해보고자 한다. 대상 및 방법 : 인체 모형 팬텀(Anderson rando Phantom, USA)을 Head, Thorax, pelvis의 3부위로 분류하여 촬영 부위의 중심에 $0.5{\times}0.5cm2$. 크기로 자른 GafChromic EBT3 film을 팬텀의 표면의 상, 하, 좌, 우와 팬텀의 표면에서 2cm깊이의 상, 하, 좌, 우, 중심에 위치시킨 뒤 토모테라피(Hi Art)와 Novalis Tx의 OBI를 이용하여 surface dose와 inner dose를 각각 3회씩 반복 측정한다. 측정 된 film은 RIP version6.0을 이용하여 값을 산출한 뒤 일원분산분석법을 이용하여 선량의 평균값을 산출한다. 결 과 : 인체모형팬텀을 이용하여 MVCT와 CBCT를 시행한 결과 MVCT inner dose의 측정값은 head에서 $15.43cGy{\pm}6.05$, thorax에서 $16.62cGy{\pm}3.08$, pelvis에서 $16.81cGy{\pm}5.24$로 나타났으며, CBCT inner dose는 head에서 $13.28{\pm}3.68$, thorax에서 $13.66{\pm}4.04$, pelvis에서 $15.52{\pm}3.52$의 값을 나타냈다. Surface dose의 측정 값은 MVCT 시행 시 head에서 $11.64{\pm}4.05$, thorax에서 $12.16{\pm}4.38$, pelvis에서 $12.05{\pm}2.71$로 나타났으며, CBCT의 경우 head에서 $14.59{\pm}3.51$, thorax에서 $15.82{\pm}2.89$, pelvis에서 $17.48{\pm}2.80$을 나타내었다. 결 론 : Inner dose의 경우 kV energy를 사용하는 CBCT보다 MV energy를 사용하는 MVCT에서 head에서 1.16배, thorax에서 1.22배, pelvis에 서 1.08배 높게 나타났으며, Surface dose의 경우 MVCT보다는 CBCT의 head에서 1.25배, thorax에서 1.30배, pelvis에서 1.45배 높게 측정되었다. Imaging dose는 치료 선량에 비해 작은 양이지만 daily로 시행되는 만큼 정상조직에 일정부분 영향을 미칠 것으로 생각된다. 하지만 IMRT치료를 위해서는 영상유도를 통한 IGRT가 반드시 병행되어 치료계획과 실제치료간 오차를 최소화하여야 한다. 따라서 환자가 받는 imaging dose를 최소화하기 위해서는 치료계획 시 Imaging dose를 고려하여 치료계획을 수립하거나 MVCT 촬영 시 Scan 범위를 최소화하여 시행해야 될 것으로 사료된다.

Purpose : In case of the intensity modulated radiation therapy (IMRT) using Tomotherapy and linear accelerator (Linac), it was to compare and to evaluate the imaging dose of MVCT and CBCT that were performed daily for the correct set up of the patient. Materials and Methods : The human body model Phantom (Anderson rando Phantom, USA) was divided into the three parts as Head, Thorax, pelvis, and after GafChromic EBT3 film cut to the size of $0.5{\times}0.5cm2$.in the center of the recording area were situated on the ant, post, left, and right surface of the phantom and 2cm in depth from the ant, post, left, right, and center surface of the phantom, the surface dose and inner dose were measured repeatedly three times, respectively, using the tomotherapy (Hi Art) and the OBI of NovalisTx. The measured film calculated the output value by RIP version6.0 and then the average value of the dose was calculated by the one-way analysis of variance. Results : Using the human body model phantom, the results of MVCT and CBCT performance were that measurements of MVCT inner dose were showed $15.43cGy{\pm}6.05$ in the head, $16.62cGy{\pm}3.08$ in the thorax, $16.81cGy{\pm}5.24$ in the pelvis, and measurements of CBCT inner dose were showed $13.28{\pm}3.68$ in the head, from $13.66{\pm}4.04$ in the thorax, $15.52{\pm}3.52$ in the pelvis. The measurements of surface dose were showed in case of MVCT performance, $11.64{\pm}4.05$ in the head, $12.16{\pm}4.38$ in the thorax, $12.05{\pm}2.71$ in the pelvis, and in case of CBCT performance, $14.59{\pm}3.51$ in the head, $15.82{\pm}2.89$ in the thorax, $17.48{\pm}2.80$ in the pelvis, respectively. Conclusion : In case of Inner dose, the MVCT using MV energy showed higher than the CBCT using kV energy at 1.16 times in the head, at 1.22 times in the thorax, at 1.08 times in the pelvis, and in case of surface dose, the CBCT was higher than MVCT, at 1.25 times in the head, at 1.30 times in the thorax, at 1.45 times in the pelvis. Imaging dose was a small amount compared to the therapeutic dose but it was thought to affect partially to normal tissue because it was done in daily schedule. However, IMRT treatment was necessarily parallel with the IGRT treatment through the image-guide to minimize errors between planned and actual treatment. Thus, to minimize imaging dose that the patients receive, when planning the treatment, it should be set up a treatment plan considering imaging dose, or it must be performed by minimizing the scan range when shooting MVCT.

목 적 : 표재성 종양 치료를 위하여 선택한 전자선은 bolus와 동시에 사용할 경우 표면선량에 급격한 변화를 보이게 되며 이는 치료결과의 중요한 변수로 작용할 수 있다. 이에 본 논문에서는 전자선 치료에서 bolus가 적용될 경우 표면선량을 좌우할 수 있는 4 가지 변수에 따른 치료계획시스템(Treatment Planning System, TPS)의 표면선량 계산 값과 실제 측정값을 비교 분석하였다. 대상 및 방법 : 치료계획시스템(Pinnacle 9.2, philips, USA)과 실제 측정값을 비교하기 위하여 실제 치료 시 주로 발생되는 4가지 변수(A: bolus 두께 - 3, 5, 10 mm, B: 조사야 크기 - $6{\time}6$, $10{\time}10$, $15{\time}15cm2$, C: 에너지 - 6, 9, 12 MeV, D: 겐트리 각도 - 0, $15^{\circ}$)를 설정하였다. 16 cm 두께의 solid water phantom을 이용하여 bolus(Action Products, USA) 없이 전산화단층촬영(lightspeed ultra 16, General Electric, USA)을 시행하였고 치료 계획은 TPS 상에서 각각 3, 5, 10 mm bolus를 생성하여 A, B, C, D를 조합한 총 54개의 beam으로 계획하였다. 이때 SSD 100 cm, 300 MU를 조사하였고 TPS와 실제 측정값을 비교 분석하기 위해 EBT3 film(International Specialty Products, NJ, USA)을 이용해 iso-center에 위치시켜 2회 반복 측정하였다. 측정된 film은 디지털 평판 스캐너(Expression 10000XL, EPSON, USA)와 선량 농도 분석시스템(Complete Version 6.1, RIT, USA)을 사용하여 각각의 평균값과 표준편차 값으로 분석하였다. 결 과 : bolus 두께에 따른 값은 3, 5, 10 mm에서 실제 측정된 값이 TPS의 계산 값보다 각각 101.41%, 99.58%, 101.28%, 표준편차는 각각 0.0219, 0.0115, 0.0190 으로 나타났다. 조사야 크기에 따른 실제 측정값은 $6{\time}6$, $10{\time}10$, $15{\time}15cm2$ 각각 계산 값에 비해 99.63%, 101.40%, 101.24%, 표준편차는 0.0138, 0.0176, 0.0220 으로 나타났다. 에너지에 따른 값은 상대적으로 6, 9, 12 MeV 각각 99.72%, 100.60%, 101.96%, 표준편차는 0.0200, 0.0160, 0.0164로 나타났다. 빔 각도에 따른 실제 측정값은 계산된 값에 비하여 0, $15^{\circ}$에서 각각 100.45%, 101.07%, 표준편차는 0.0199, 0.0190 으로써 $15^{\circ}$에서 $0^{\circ}$보다 0.62% 높게 측정되었다. 결 론 : 본 논문에서 사용한 변수에 따른 계산 값과 측정값을 분석한 결과 5 mm bolus, $6{\time}6cm2$ 조사야, 저 에너지 전자선, $0^{\circ}$ 겐트리 각도에서 TPS로 계산한 값이 측정값에 더 가까웠지만 다른 변수를 적용한 비교에서도 최대 2% 오차범위 내에 포함되는 결과를 보였다. 전자선과 bolus를 동시에 사용하는 경우 본 논문에서 선택된 변수의 범위를 벗어난다면 각각의 변수에 따라 실제 측정값이 TPS와 달라질 수 있기 때문에 정확한 표면선량에 대한 QA를 반드시 실시해야 한다.

Purpose : If electron, chosen for superficial oncotherapy, was applied with bolus, it could work as an important factor to a therapy result by showing a drastic change in surface dose. Hence the calculation value and the actual measurement value of surface dose of Treatment Planning System (TPS) according to four variables influencing surface dose when using bolus on an electron therapy were compared and analyzed in this paper. Materials and Methods : Four variables which frequently occur during the actual therapies (A: bolus thickness - 3, 5, 10 mm, B: field size - $6{\time}6$, $10{\time}10$, $15{\time}15cm2$, C: energy - 6, 9, 12 MeV, D: gantry angle - $0^{\circ}$, $15^{\circ}$) were set to compare the actual measurement value with TPS(Pinnacle 9.2, philips, USA). A computed tomography (lightspeed ultra 16, General Electric, USA) was performed using 16 cm-thick solid water phantom without bolus and total 54 beams where A, B, C, and D were combined after creating 3, 5 and 10 mm bolus on TPS were planned for a therapy. At this moment SSD 100 cm, 300 MU was investigated and measured twice repeatedly by placing it on iso-center by using EBT3 film(International Specialty Products, NJ, USA) to compare and analyze the actual measurement value and TPS. Measured film was analyzed with each average value and standard deviation value using digital flat bed scanner (Expression 10000XL, EPSON, USA) and dose density analyzing system (Complete Version 6.1, RIT, USA). Results : For the values according to the thickness of bolus, the actual measured values for 3, 5 and 10 mm were 101.41%, 99.58% and 101.28% higher respectively than the calculation values of TPS and the standard deviations were 0.0219, 0.0115 and 0.0190 respectively. The actual values according to the field size were $6{\time}6$, $10{\time}10$ and $15{\time}15cm2$ which were 99.63%, 101.40% and 101.24% higher respectively than the calculation values and the standard deviations were 0.0138, 0.0176 and 0.0220. The values according to energy were 6, 9, and 12 MeV which were 99.72%, 100.60% and 101.96% higher respectively and the standard deviations were 0.0200, 0.0160 and 0.0164. The actual measurement value according to beam angle were measured 100.45% and 101.07% higher at $0^{\circ}$ and $15^{\circ}$ respectively and standard deviations were 0.0199 and 0.0190 so they were measured 0.62% higher at $15^{\circ}$ than $0^{\circ}$. Conclusion : As a result of analyzing the calculation value of TPS and measurement value according to the used variables in this paper, the values calculated with TPS on 5 mm bolus, $6{\time}6cm2$ field size and low-energy electron at $0^{\circ}$ gantry angle were closer to the measured values, however, it showed a modest difference within the error bound of maximum 2%. If it was beyond the bounds of variables selected in this paper using electron and bolus simultaneously, the actual measurement value could differ from TPS according to each variable, therefore QA for the accurate surface dose would have to be performed.

목 적 : 방사선 치료 시 치료기법에 따라 피부에 흡수되는 선량은 달라진다. 본 연구에서는 유방전절제술을 시행한 환자의 방사선 치료 시 치료 기법에 따른 표면선량 및 깊이에 따른 피부선량을 평가하고자 한다. 대상 및 방법 : 조직등가물질로 구성된 팬톰(I'mRT, IBA)을 이용하여 전산화단층촬영을 시행 한 후 치료계획시스템에 의해 인체의 흉벽과 같이 가상의 표적과 정상조직을 설정하였다. 총 5가지의 치료계획(Wedged Tangential technique, 4-field IMRT, 7-field IMRT, TOMO DIRECT, TOMO HELICAL)에 대해 6MV 광자선을 이용해 최적의 치료계획을 수립하였다. 흉벽의 표면선량을 측정하기 위해 Gafchromic EBT3필름 이용하여 팬톰의 표면에 밀착 시킨 후 내측(0~4 cm), 중심측(4~12 cm), 외측(12~16 cm)으로 구분하여 분석 하였고, 깊이에 따른 피부선량을 측정하기 위해 팬톰 단면 사이에 필름을 삽입 후 측정하여 흉벽의 내측(3지점), 중심측(4지점), 외측(3지점)에 대해서 1~6 mm 깊이 별로 측정하여 분석하였다. 결 과 : 흉벽의 표면선량 측정결과 처방선량 기준으로 TOMO DIRECT에서 47~70%로 가장 높게 측정 되었으며, 7-field IMRT의 경우 35~46%로 가장 낮은 선량을 보였다. 깊이에 따른 피부선량 측정결과 TOMO DIRECT와 TOMO HELICAL에서 다른 치료기법에 비해 1 mm, 2 mm, 5 mm깊이에서 처방선량의 75%, 80%, 90% 이상으로 모든 영역에서 상대적으로 높은 선량이 측정 되었으며, 특히 TOMO DIRECT의 경우 접선인자 영향에 의해 중심 측의 1 mm, 2 mm깊이에서 처방선량의 80%, 90%이상의 선량이 측정 되었다. 결 론 : 유방전절제술을 시행한 환자의 방사선 치료 시 선형 가속기를 이용한 치료 기법에 비해 TOMO DIRECT와 TOMO HELICAL에서 표면 및 피부선량이 높게 나타났으며, 표면으로부터 1 mm깊이의 피부영역에서 75% 이상의 충분한 선량을 전달 할 수 있었다.

Purpose : The purpose of this study was to evaluate the surface and superficial dose for patients requiring postmastectomy radiation therapy(PMRT) with different treatment techniques. Materials and Methods : Computed tomography images were acquired for the phantom(I'mRT, IBA) consisting of tissue equivalent material. Hypothetical chestwall and lung were outlined and modified. Five treatment techniques(Wedged Tangential; WT, 4-field IMRT, 7-field IMRT, TOMO DIRECT, TOMO HELICAL) were evaluated using only 6MV photon beam. GafChromic EBT3 film was used for dose measurements at the surface and superficial dose. Surface dose profiles around the phantom were obtained for each treatment technique. For superficial dose measurements, film were used inside the phantom and analyzed superficial region for depth from 1-6mm. Results : TOMO DIRECT showed the highest surface dose by 47~70% of prescribed dose, while 7-field IMRT showed the lowest by 35~46% of prescribed dose. For the WT, 4-field IMRT and 7-field IMRT, superficial dose were measured over 60%, 70%, and 80% for 1mm, 2mm, and 5mm depth, respectively. In case of TOMO DIRECT and TOMO HELICAL, over 75%, 80%, and 90% of prescribed dose was measured, respectively. Surface and superficial dose range were uniform in overall chestwall for the 7-field IMRT and TOMO HELICAL. In contrast, Because of the dose enhancement effect with oblique incidence, The dose was gradually increased toward the obliquely tangential angle for the WT and TOMO DIRECT. Conclusion : For PMRT, TOMO DIRECT and TOMO HELICAL deliver the higher surface and superficial doses than treatment techniques based linear accelerator. It showed adequate dose(over 75% of prescribed dose) at 1mm depth in skin region.

목 적 : 영상유도방사선치료 시 사용하는 콘빔 CT는 치료자세 오차를 확인하는 중요한 수단이지만 피폭선량을 증가 시키는 단점이 있다. 이에 본 연구는 콘빔 CT의 시행주기를 격일로 하는 시나리오를 만들어 유용성을 평가하고자 한다. 대상 및 방법 : 콘빔 CT를 이용하여 세기변조방사선치료를 받은 전립선암 환자 9명을 대상으로 실제 치료 시 매일 콘빔 CT로 치료자세 오차를 분석하여 보정한 값을 바탕으로 격일로 콘빔 CT를 시행하는 시나리오를 만들었다. 시나리오에서 콘빔 CT를 시행하지 않은 날의 치료자세 오차 값을 실제 치료 시의 치료중심점에서 이동하여 치료계획시스템(Pinnacle 9.2, Philips, USA)에 적용한 후 실제 치료와 동일한 조건으로 재 치료계획을 수립하였으며, 이를 바탕으로 PTV(Planning Target Volume)와 정상장기의 선량분포를 비교 분석하였다. 결 과 : 매일 콘빔 CT를 시행하였을 때의 치료자세 오차 값을 기준으로 격일로 콘빔 CT를 시행하는 시나리오에서는 X, Y, Z축으로 각각 $0.2{\pm}0.73mm$, $0.1{\pm}0.58mm$, $-1.3{\pm}1.17mm$ 차이가 나타났다. 이를 치료계획에 적용하여 재 치료계획을 수립하여 선량분포를 평가한 결과는 매일 콘빔 CT를 시행한 결과와 비교하여 PTV의 Dmean : -0.17 Gy, $D_{99%}$ : -0.71 Gy, 차이가 나타났다. 정상 장기는 직장 벽의 $V_{66}$ : 1.55%, 방광의 $V_{66}$ : -0.76% 차이가 나타났다. 결 론 : 격일로 콘빔 CT를 시행하였을 경우 콘빔 CT에 의한 피폭선량을 감소시키고 촬영으로 인한 추가적인 치료시간을 줄여 줄 수 있다. 또한 PTV, 정상장기의 선량분포의 차이가 크지 않으므로 환자의 상태의 따라 격일 콘빔 CT의 적용을 고려할 수 있을 것으로 사료된다.

Purpose : Cone Beam Computed Tomography(CBCT) in Image Guided Radiation Therapy(IGRT), Set-up error can be reduced but exposure dose of the patient due to CBCT will increase. Through this study, we are to evaluate by making a scenario with the implementation period of CBCT as every other day. Materials and Methods : Of prostate cancer patients, 9 patients who got a Intensity Modulated Radiation Therapy(IMRT) with CBCT in IGRT were analyzed. Based on values corrected by analyzing set-up error by using CBCT every day during actual treatment, we created a scenario that conducts CBCT every other day. After applying set-up error values of the day not performing CBCT in the scenario to the treatment planning system(Pinnacle 9.2, Philips, USA) by moving them from the treatment iso-center during actual treatment, we established re-treatment plan under the same conditions as actual treatment. Based on this, the dose distribution of normal organs and Planning Target Volume(PTV) was compared and analyzed. Results : In the scenario that performs CBCT every other day based on set-up error values when conducting CBCT every day, average X-axis : $0.2{\pm}0.73mm$, Y-axis : $0.1{\pm}0.58mm$, Z-axis : $-1.3{\pm}1.17mm$ difference was shown. This was applied to the treatment planning to establish re-treatment plan and dose distribution was evaluated and as a result, Dmean : -0.17 Gy, D99% : -0.71 Gy of PTV difference was shown in comparison with the result obtained when carrying out CBCT every day. As for normal organs, V66 : 1.55% of rectal wall, V66 : -0.76% of bladder difference was shown. Conclusion : In case of a CBCT perform every other day could reduce exposure dose and additional treatment time. And it is thought to be able to consider the application depending on the condition of the patient because the difference in the dose distribution of normal organs, PTV is not large.