Earticle

의료기관에서 최근 많이 사용되고 있는 친환경 소재 방사선 차폐체는 시트 형태로 제작되어 Apron의 재료로 활용되고 있다. 친환경 Apron의 차폐성능은 납당량을 기준으로 제시되고 있으며, 납당량은 0.25∼0.50mmPb로 제시 되고 있다. 납이 주재료 사용되는 차폐체인 경우 납의 우수한 가공성으로 인해 두께로 차폐성능을 조절할 수 있다. 그러 나 친환경 차폐시트는 차폐재료의 함량, 베이스 재료인 고분자 물질의 물성, 공정과정의 기술적 차이에 따라 차폐성능이 변화되어 두께 기준의 차폐성능을 제어하기가 어렵다. 본 연구에서는 이러한 문제점을 해결하고자 두께를 기준으로 차 폐시트를 제작하여 차폐성능을 평가, 비교하였다. 동일한 시트 제작공정을 제시하여 두께를 제어할 수 있는 캘린더 공정 의 압연 기술을 적용하였고 여러층의 적층 구조와 단일 구조로 제작된 두 시트의 두께별 차폐성능을 비교하여 5%대의 차이를 관찰하였다. 그 결과 여러 층으로 차폐한 적층 구조 차폐시트가 더 효과적임을 증명하는 동시에 두께 중심의 차폐성능의 가능성을 제시하였다.

Radiation shielding of affinity material, which is widely used in medical institutions, is made in sheet form and is mainly applied to apron. Shielding performance is presented based on lead equivalent, and is presented as 0.25-0.50mmPb. In the case of shielding materials where lead is used as the main material, the shielding performance can be adjusted by thickness due to the excellent machinability of lead. However, eco-friendly shielding sheets are difficult to control shielding performance based on thickness criteria as shielding performance varies depending on the content of shielding materials, the properties of polymeric materials that are base materials, and the technical differences in the process. In this study, shielding sheets were manufactured based on thickness to solve these problems and the shielding performance was compared in this study. As a result, it was shown that the laminated structure shielding sheet was more effective.

In this paper, we develop a 94-GHz single balanced mixer with low conversion loss using planar Schottky diodes on a GaAs substrate. The GaAs Schottky diode has a nanoscale anode with a T-shaped disk that can yield high cutoff frequency characteristics. The fabricated Schottky diode with an anode diameter of 500 nm has a series resistance of 21 Ω, an ideality factor of 1.32, a junction capacitance of 8.03 fF, and a cutoff frequency of 944 GHz. Based on this technology, a 94-GHz single balanced mixer was constructed. The fabricated mixer shows an average conversion loss of -7.58 dB at an RF frequency of 92.5 GHz to 95 GHz and an IF frequency of 500 MHz with an LO power of 7 dBm. The RF-to-LO isolation characteristics were greater than -32 dB. These values are considered to be attributed to superior Schottky diode characteristics.

Background: In order to measure neutron energy spectra, the conventional Bonner Sphere Spectrometers (BSS) are widely used. In this spectrometer, several measurements with different size Bonner spheres are required. Operators should, therefore, place these spheres in several times to a measurement point where radiation dose might be relatively high. In order to reduce this effort, novel neutron energy spectrometer using an onion-like single Bonner sphere was proposed in our group. This Bonner sphere has multiple sensitive spherical shell layers in the single sphere. In this spectrometer, a band-shaped thermal neutron detection medium, which consists of a LiF-ZnS mixed powder scintillator sheet and a wavelength-shifting (WLS) fiber readout, was looped to each sphere at equal angular intervals. Amount of LiF neutron converter is reduced near polar region, where the band-shaped detectors are concentrated, in order to uniform the directional sensitivity. The LiF-ZnS mixed powder has an advantage of extremely high light yield. However, since it is opaque, scintillation photons cannot be collect uniformly. This type of detector shows no characteristic shape in the pulse height spectrum. Subsequently, it is diffcult to set the pulse height discrimination level. This issue causes sensitivity fluctuation due to gain instability of photodetectors and/or electric modules. Materials and Methods: In order to solve this problem, we propose to replace the LiF-ZnS mixed powder into a flexible and Transparent RUbber SheeT type LiCaAlF6 (TRUST LiCAF) scintillator. TRUST LiCAF scintillator can show a peak shape corresponding to neutron absorption events in the pulse height spectrum. Results and Discussion: We fabricated the prototype detector with five sensitive layers using TRUST LiCAF scintillator and conducted basic experiments to evaluate the directional uniformity of the sensitivity. Conclusion: The fabricated detector shows excellent directional uniformity of the neutron sensitivity.

본 연구에서는 항법정보 산출용 컴퓨터에 탑재되는 단일보드컴퓨터를 대상으로 야전 운용간 발생한 전기적 고장현상에 대하여 구조해석 관점에서 해소방안을 도출하고자 하였다. 특성요인도 분석을 통해 단일보드컴퓨터의 구조적인 문제로 중앙처리장치 기판에 크랙이 발생한 것을 확인할 수 있었고, 크랙발생 부위에 가해진 물리적인 영향으로 인해 통신기능 수행이 불가해지면서 동시에 부팅이 불가한 현상이 나타난 것으로 확인되었다. 이에 대하여 크랙현상을 유발시키는 과도응력의 위치를 찾고자 구조해석을 수행하였다. 구조해석을 통해 응력집중현상이 발생하는 부위를 확인할 수 있었고, 이를 해소시키기 위해 과도응력의 원인이 되는 부품과 구조물을 변경하는 개선방안을 수립하였다. 개선방안에 대한 검증은 구조해석을 통해 개선 전과 후의 구조물에 작용하는 응력분포를 비교하여 응력의 감소정도를 보였다. 추가적으로, 열 해석을 통해 부품 및 구조물 변경으로 인한 방열기능 유지여부를 확인하였고, 개선방안을 적용한 실 장비의 방열판 온도를 측정함으로써 실제 장비의 방열 영향성을 확인하였다.

In this study, we aim to derive a solution from the structural analysis for electrical failure of single board computers for computing navigation information. By analyzing the characteristic factor, we identify that crack occur on the central processing unit board due to a certain structural problem, and that the physical effect by the crack make communication function be impossible to perform, which it causes booting error. In order to find the location of excessive stress causing the crack, structural analysis for the single board computer is done. From the structural analysis, the areas where stress concentration occurs are identified, and improvement methods changing the structures are developed. As a result, we shows that stresses are reduced entirely on the stress distribution for the improved structure. In addition, heat analysis shows that changing the structure to reduce stresses is not affect to the heat radiation, and the thermal resistance of the actual equipment is verified by measuring the temperature of the heat sink applied with the improved structure.

An integrated structure and controller design approach for rotating cantilever beam is presented. An optimization method is developed for improving positioning performance considering the elastic deformations during high speed rotation and adopting the beam shape and the control gains as design variables. For this end, a dynamic model is setup by the finite element method according to the shape of the beam. The mass and stiffness of the beam are distributed in such a way that the closed-loop poles of the control system should be located leftmost in the complex s-plane. For optimization method, the simulated annealing method is employed which has higher probability to find the global minimum than the gradient-based down-hill methods. Sequential design and simultaneous design methods are proposed to obtain the optimal shape and controller. Simulations are performed with new designs by the two methods to verify the effectiveness of the approach and the results show that the settling time is improved for point-to-point position controls.

가새가 마찰면을 통해 에너지를 소산시키는 마찰가새(FSB)는 마찰력이 가새의 축저항력을 초과하기 전까지 탄성거동을 한다. 본 연구는 이런 FSB 거동을 바꾼 하이브리드 에너지 소산장치인 능동조임마찰가새(AFSB)를 제안한다. FSB는 마찰면에 능동적으로 조임력을 가하면 지진동을 보다 효율적으로 제어할 수 있는 AFSB로 변한다. 조임력은 컴퓨터 프로그램의 알고리즘을 통해 변동하며 제어된다. 해석결과에 의하면 AFSB는 FSB에 비해 효과적으로 에너지를 소산시켜 응답사이클이 지속될 수록 매우 효과적으로 구조물의 변위를 제어해준다. 즉, 논문 서두에 제안된 강도일정증분 알고리즘은 약진 및 중진의 지진동에 변위와 밑면전단력을 효과적으로 제어함을 확인하였다. 강진의 경우에 AFSB는 응답초기부터 미끄러지는 특성으로 인해 오버슈팅이 발생하여 이를 극복하기위해 최대변위를 제한하도록 알고리즘을 수정하고 결과를 확인하였다.

Structural bracing concept equipped with a new and efficient friction based energy dissipation device is referred to Friction Slip Brace (FSB) where the behavior of the brace components is elastic until the axial resistant force in the brace exceeds the friction force developed at the frictional interface of the device. In this study, the FSB concept is modified and new type of hybrid energy dissipation device, the Active Friction Slip Braces (AFSB), is described. The FSB is by far improved in the AFSB by inclusion of an active clamping mechanism on the friction interface. The clamping action regulated by the developed algorithm is altered during the response of the building. The results indicate that the action of dissipating vibrational energy in the AFSB impacts on the response at later cycles by keeping the drift amplitudes at much lower levels, revealing overshooting problem due to its early slippage. Providing predetermined constant incremental strengths to the building by AFSB members improves response by reducing drift amplitudes and base shear under small and medium amplitude ground accelerations. However, early slippage of AFSB members cause overshooting of the response compared to FSB under large amplitude ground excitation. The operational algorithm of the AFSB members may be modified to prevent it.

본 논문에서는 단일 영상을 기반으로 초해상도를 생성하는 과정에서 계층 구조를 거쳐 추출된 보조 경계 특징을 이용한 방법을 제안하였다. 초해상도의 품질을 향상시키기 위해서는 영상 내 경계 영역을 선명하게 표현하 면서도 각 영역의 형태를 명확하게 구분하여야 한다. 제안하는 방법은 초해상도 과정에서 품질을 결정하는 중요한 요인인 경계 영역을 입력 영상의 구조적 형태를 유지하면서 개선된 초해상도 결과를 생성하기 위해 딥러닝 기반의 초해상도 방법에서 영상의 경계 영역 정보를 보조적으로 활용하는 구조를 사용하였다. 딥러닝 기반의 초해상도를 수행하기 위한 그룹 컨볼루션 구조에 더해 보조 경계 추출을 위한 고주파 대역의 정보를 기반으로 별도의 계층적 구조의 경계 누적 추출 과정을 수행하여 이를 보조 특징으로써 활용하는 방법을 제안하였다. 실험 결과 기존 초해 상도 대비 PSNR과 SSIM에서 약 1%의 성능 향상을 보였다.

In this paper, we proposed a method using sub-edge information extracted through a hierarchical structure in the process of generating super resolution based on a single image. In order to improve the quality of super resolution, it is necessary to clearly distinguish the shape of each area while clearly expressing the boundary area in the image. The proposed method assists edge information of the image in deep learning based super resolution method to create an improved super resolution result while maintaining the structural shape of the boundary region, which is an important factor determining the quality in the super resolution process. In addition to the group convolution structure for performing deep learning based super resolution, a separate hierarchical edge accumulation extraction process based on high-frequency band information for sub-edge extraction is proposed, and a method of using it as an auxiliary feature is proposed. Experimental results showed about 1% performance improvement in PSNR and SSIM compared to the existing super resolution.

본 연구는 객관적 노후 기준인 연령과, 스스로를 노인이라고 생각하는지 여부인 주관적 노후 기준에 따라 노인1인가계를 유형화하고, 각 유형별 가계경제구조와 소비지출패턴의 차이를 살펴봄으로써 노인1인가계의 다양성을 규명하는 것을 목적으로 하였다. 분석 자료로는 국민노후보장패널(Korean Retirement and Income Study: KReIS) 6차년도(2015) 데이터를 활용하였다. 각 주요 결과는 다음과 같다. 첫째, 전체 조사대상자 791명은 스스로 노인이라고 생각하지 않는 60대인 [유형1] 14.7%(116명), 스스로 노인이라고 생각하는 60대 [유형2] 16.2%(128명), 스스로 노인이라고 생각하지 않는 70대 [유형3] 6.7%(53명), 스스로 노인이라고 생각하는 70대 [유형4] 62.5%(494명)으로 분류되었다. 둘째, 인구통계특성을 살펴본 결과 동일한 연령대라도 노인이라고 생각하는 [유형2], [유형4]에서 여성과 미취업 상태의 비율이 더 높게 나타났다. 셋째, 객관적․주관적 노후 유형별 노인1인가계의 가계 경제의 특성을 비교해본 결과, 총소득과 총지출, 총자산은 [유형1], [유형2], [유형4], [유형3] 순으로 나타났다. 특히 소득원천의 경우에는 동일한 연령이라도 주관적 노후에 따라 유의미한 차이가 있는 것으로 나타났는데 주관적으로 노인이라고 인식하는 [유형2], [유형4]에서는 공적이전소득, 사적이전소득, 근로소득 순으로 소득이 발생한 반면, 주관적으로 노인이라고 인식하지 않는다고 응답한 [유형1], [유형3]에서는 근로소득이 가장 많았으며, 그 다음으로 공적이전소득, 사적이전소득 순으로 소득이 발생했다. 넷째, 객관적․주관적 노후 유형별로 소비지출패턴을 살펴본 결과, 60대가 70대보다 소득과 지출의 규모가 더 컸기 때문에 소비지출액수는 객관적 연령에 따라 집단 간 차이가 나타났으나, 지출비중의 경우에는 주관적 노후인식에 따라 차이가 나타났다. 주관적으로 노인이라고 생각하는 [유형2]와 [유형4]의 경우 그렇지 않은 집단에 비해 식비와 주거수도광열비, 문화생활비의 비중이 높게 나타났으며, 주관적으로 노인이라고 생각하지 않는 [유형1]과 [유형3]의 경우 교통비, 외식비의 지출 비중이 상대적으로 높게 나타났다. 이는 동일한 연령대라도 주관적 노후인식에 따라 노인1인가계의 생활양식이 다르며, 한정된 자원을 욕구에 따라 비목별로 다른 비중으로 배분하고 있다는 것을 보여준다. 이상의 논의를 토대로 객관적인 연령 외에 주관적 노후인식을 고려한 정책적, 마케팅적 접근의 필요성과 재무교육의 필요성을 제언하였다. 본 연구는 동일한 연령이라도 주관적 노후 인식에 따라 가계경제구조 및 소비지출패턴에 차이가 있음을 밝힘으로써 노인1인가계 집단 내의 다양성을 규명하고, 노인1인가계가 능동적인 소비자로서 한정된 자원을 우선순위에 따라 배분하고 있다는 것을 밝혀냈다는 점에서 의의가 있다.

The purpose of this study was to understand the single elderly households, which account for one third of elderly households in Korea, as an active elderly consumer and to identify diversity within the group. This study is classified the single elderly consumer into four groups on the basis of objective age and subjective aging perception, and compared economic characteristics and consumption patterns. The main results are as follows. First, in the case of the income source, there was a meaningful difference according to the subjective aging. In the group that perceived as the elderly subjectively, public and private transfer income were higher than earned income. On the other hand, elderly consumer who do not perceive themselves as the elderly have the earned income was the main source of income. Second, as a result of examining the pattern of consumption expenditure, the proportion of expenditure was significantly different according to the degree of subjective aging. The proportion of transportation expenditure and eating out expenditure was relatively high in groups that do not think of themselves as elderly people of the same age. This shows that the lifestyle of the single elderly consumer is different according to the aging recognition types and they actively distributes the proportion of expenditure differently according to the their desire. Based on the above discussion, we suggested the necessity of multifaceted approaches in policy, education and marketing within single elderly consumer. This study identifies the diversity within a single elderly group, and it is significant that a single elderly person is an active consumer and reflects the desire to distribute household consumption expenditure.

본 논문에서는 vertical coupling이라는 새로운 구조를 통해 구현한 광대역 rat race ring을 이용하여 광대역 단일 평형 다이오드 혼합기를 설계 및 구현하였다. RF주파수 범위는 GHz, LO의 주파수 범위는 GHz의 광대역 주파수 범위에서 140 MHz의 IF 주파수를 선택하였다. 입력되는 LO 신호가 2.74 GHz에서 6 dBm, RF의 입력 신호가 2.6 GHz에서 40 dBm일 때의 출력 포트(IF)에서의 변환손실은 7.5 dB와 30 dB의 RF와 LO의 우수한 격리도를 측정 결과에서 각각 나타내었다. GHz의 광대역 RF주파수 범위 내에서 평균 10 dB의 변환손실과 30 dB의 높은 RF와 LO 격리도, 45 dB의 LO와 IF 격리도를 측정결과에서 각각 나타내었다.

In this paper, a broadband single balanced mixer is presented using a wideband rat-race implementation by vertical coupling. Frequency is selected as GHz for RF, GHz for LO, and 140 MHz for IF signals. When LO signal with 6 dBm at 2.7 GHz is injected, a conversion loss of 7.5 dB and RF to LO isolation of 30 dB are obtained. Also, an average conversion loss of 10 dB, RF to LO isolation of 30 dB, and LO to IF isolation of 45 dB are obtained for frequency band of GHz.

This paper proposes a new single phase variable structure control (SPVSC) for mismatched uncertain systems. A new sliding mode without reaching phase is designed to address two most important problems in the variable structure control area: 1) the system states are in sliding mode at the initial time movement; and 2) using only output variables directly. First, a new sufficient condition in terms of linear matrix inequality is derived such that the existence of a sliding surface guarantees asymptotic stability of the sliding mode dynamics from the initial time instant. Second, a static output feedback SPVSC law is designed to force the system states to stay in the sliding surface from beginning to end. Final, the lateral motion of a B-26 aircraft is simulated to demonstrate the advantages and effectiveness of the proposed SPVSC scheme.

Single chain Fv antibody fragment against c-Met (wt-VH-VL) poses loss of function because of poor structural stability due to reduction of disulfide bond while expressed in Escherichia coli cytoplasmic reducing condition. Previously we have reported its functional expression in a mutant E. coli strain containing cytoplasmic non-reducing condition, which lacks the genes for enzymes (gor, trx) breaking the disulfide bonds and favors the disulfide bond formation. But by nature and in vitro evolution it has been found that there are structurally stable domains exists without disulfide bond. Therefore it was hypothesized and successfully demonstrated that it is possible to generate a structurally stable antibody fragments by grafting the complementary determining region (CDR) loops into a stable antibody framework structures. Here we successfully employed the same CDR-loop grafting methodology to generate a stable anti-c-Met chimeric scFv (ch-VH-VL) by grafting the CDR loops into a highly stable human antibody framework structure (H3k3). Comparative analysis of the predicted models of three dimensional structures of wt-VH-VL and ch-VH-VL showed local hydrophobic interaction pattern plays the key role in retaining internal network interactions of the fold of variable domains in the absence of disulfide bond. Finally the observed key interaction pattern has been supported by the presence and absence of such pattern on available X-ray crystal structures of stable and unstable domains respectively.

본 논문에서는 시분산 채널에서 발생되는 진폭과 위상 찌그러짐을 보상하기위한 적응 등화 알고리즘에서 MCMA와 MDD를 병렬 구조로 구현한 PMCMA-MDD (Paralled Modified Constant Modulus Algorithm-Modified Decision Directed )와 단일 구조로 구현한 DW-MCMA (Dual Weight-Modified Constant Modulus Algorithm)의 성능을 비교, 평가하였다. 이들 알고리즘은 기본적으로 MCMA와 RCA의 축소 신호점을 이용하는 비용 함수를 적용하여 빠른 수렴 속도와 적은 잔류 isi를 얻을 수 있다. 구조적으로 PMCMA-MDD 알고리즘은 2개의 독립적인 등화 필터를 병렬로 사용하며 DW-MCMA 알고리즘은 1개의 등화 필터를 이용하여 2번에 걸쳐 탭 계수를 갱신한다. 2가지 알고리즘에 대한 컴퓨터 시뮬레이션을 통해 수신측에서 복원된 신호 성상도, 잔류 isi 특성 곡선에의한 수렴 시간과 수렴 속도, 정규화 MSE 및 주어진 시분산 채널의 신호대 잡음비에서 SER (Symbol Error Rate)등의 성능을 비교하였으며, 시뮬레이션 결과 모든 성능에서 PMCMA-MDD가 DW-MCMA보다 우월함을 알 수 있었다.

This paper deals with the performance comparison and evaluation of blind adaptive equalizer, the PMCMA-MDD and DW-MCMA, that is used for compensation of the amplitude and phase distortion which occurs in the time dispersive channel. Basically, these algorithms are modification of MCMA cost fuction in order to obtain the fast convergence speed and reduced residual isi by taking the parallel and serial double structured and the combination of the concept of RCA for the updating the tap coefficient. We implements the algorithm of it and compare the recovered constellation, residual isi, MSE charateristics curve and SER in the signal to noise ratio given the time dispersive channel. As a result of simulation, the PMCMA-MDD has a good in recovered constellation than DW-MCMA. But in the SER, the DW-MCMA has a good than PMCMA-MDD.

This paper compares ingle round nancing with staged nancing.The main idea is that di??erent nancing modes will give rise todi??erent information structure. When enough fund is provided atthe outset, it is easier to tell a bad project than a god projectwhile the reverse is true when bare minimum nance is providedat the start. The value of the option to liquidate depends on theinformation structure induced by the nancing mode. We showthat while staged nancing imposes more stringent requirementon the quality of information the lender has, it also allows moreprojects to be nanced.

The single-crystal structure of fully dehydrated partially $Li^+$-exchanged zeolite Y, ${\mid}Li_{50}Na_{25}{\mid}[Si_{117}Al_{75}O_{384}]$-FAU, was determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group $Fd\bar{3}m$ at 100(1) K. Ion exchange was accomplished by flowing stream of 0.1 M aqueous $LiNO_3$ for 2 days at 293 K, followed by vacuum dehydration at 623 K and $1{\times}10^{-6}$ Torr for 2 days. The structure was refined using all intensities to the final error indices (using only the 801 reflections with ($F_o$ > $4{\sigma}(F_o)$) $R_1/R_2=0.043/0.140$. The 50 $Li^+$ ions per unit cell are found at three different crystallographic sites. The 19 $Li^+$ ions occupy at site I' in the sodalite cavity: the $Li^+$ ions are recessed 0.30 ${\AA}$ into the sodalite cavity from their 3-oxygens plane (Li-O = 1.926(5) ${\AA}$ and $O-Li-O=117.7(3)^{\circ}$). The 20 $Li^+$ ions are found at site II in the supercage, being recessed 0.23 ${\AA}$ into the supercage (Li-O = 2.038(5) ${\AA}$ and $O-Li-O=118.7(3)^{\circ}$). Site III' positions are occupied by 11 $Li^+$ ions: these $Li^+$ ions bind strongly to one oxygen atom (Li-O = 2.00(8) ${\AA}$). About 25 $Na^+$ ions per unit cell are found at four different crystallographic sites: 4 $Na^+$ ions are at site I, 5 at site I', 12 at site II, and the remaining 4 at site III'.