Earticle

본 연구의 목적은 X-선, 양성자, 중입자를 이용한 방사선치료 시 방사선에 따른 물리적 특징을 확인하고 방사선치료계 획을 비교하고자 한다. MatRad 몬테카를로 시뮬레이션 프로그램에서 제공하는 box 팬톰을 이용하여 방사선에 따른 물리적 특징을 확인하고, TG-119 팬톰을 통해 방사선전산화치료계획을 수립하여 비교하였다. 물리적 특징 비교를 위해 1문 조사를 시행하고, 방사선치료계획 비교를 위해 X-선은 7문조사, 양성자와 중입자는 각각 2문 조사를 시행하였다. Box 팬톰을 이용한 방사선 별 target 평균선량은 X-선, 양성자, 중입자 각각 1.97±0.21, 1.99±0.05, 2.00±0.04 Gy였다. TG-119 팬톰을 이용한 방사선 별 outerTarget과 core 평균선량은 X-선, 양성자, 중입자 각각 1.66±0.03, 1.67±0.03, 1.67±0.02, 0.58±0.18, 0.58±0.21, 0.64±0.20 Gy였다. 본 연구를 통해 방사선에 따른 물리적 특성과 전산화치료계획에 대한 결과는 방사선전산화치료계획 수립과 중입자 치료기 도입에 따른 기초 자료로 활용될 것이라 사료된다.

This study aims to characterize the physical properties following x-ray, proton, and heavy ion radiation treatment and to compare the treatment plans accordingly. After each radiation treatment, the physical properties were observed using a box phantom simulation from MatRad open-source Monte Carlo simulation software. In addition, the TG-119 phantom was used to establish and compare the computerized radiation treatment plans. A one-portal technique was used for the comparison of the physical characteristics. Further, for the comparison of the radiation treatment plans, seven portals were used for x-ray proton and heavy ion radiation, and two portals were used for proton and heavy ion radiation. The box phantom simulation results demonstrate that the average target dose of x-ray, proton, and heavy ion radiation was 1.97±0.21 Gy, 1.99±0.05 Gy, and 2.00±0.04 Gy, respectively. In the TG-119 phantom simulation, x-ray, proton, and carbon-ion radiation resulted in an average outer target dose of 1.66±0.03 Gy, 1.67±0.03 Gy, and 1.67±0.02, and an average absorbed dose at the core of 0.58±0.18 Gy, 0.58±0.21 Gy, and 0.64±0.20 Gy, respectively. The simulated results of the physical properties and computerized treatment plans using the three types of radiation from this study are expected to serve as the preliminary data for establishing computerized radiation treatment plans and implementing heavy ion therapy devices.

지체장애인의 접근권 보장을 위해 건축물에서 경사로의 설치는 매우 중요한 사안이다. 하지만 반대 급부로 경사로 설치로 인해 건축물 공간 활용의 효율성 측면에서 다소간의 문제가 발생될 수 있다. 따라서 본 연구는 경사로의 기울기에 따른 극복가능정도를 파악하기 위해 30명의 모집단을 구성하고 각 경사로 극복을 시행하여 최적의 경사로 기울기를 파악해 보고자 하는데 그 목적이 있으며, 이 실험은 향후 적용되어 질 수 있는 건축물의 경사로 설치에 있어 기초적인 자료로 활용될 수는 있을 것이다.

Most people with disabilities depend upon wheelchair use for mobility. For these people, wheelchair use is an important way to achieve independent locomotion in order to overcome differences in pavement surface levels. Therefore, this study aims to consider the characteristics of ramp gradients that incorporates a universal design. This study examined the effects of ramp slope(1/12, 1/10, 1/8 and 1/6) on physical characteristics and psychological characteristics fo wheelchair users which slope would be the suitable for wheelchairs, in order to propese a ramp slope that incorporates a universal design

본 연구는 수작업으로 이루어진 제조현장에서 제조 프로세스를 최적화할 수 있도록 시뮬레이션을 통한 디지털 트윈 구현 방안을 제안하고자 한다. 수작업 모션을 센서로 수집하고 동작 인식에 대하여 반복적인 실험 데이터로 제조 프로세스를 최적화하는 지식관리메커니즘을 제안 범위로 한다. 연구목적 달성을 위하여 물류현장 모의실험을 실시하였는데, 작업자의 경험으로 나타난 기초적 지식에 작업시뮬레이션을 반복 경험하게 함으로써 최 적화된 디지털 트윈을 생성할 수 있는 방안을 마련하였다. 실험결과, 디지털 트윈을 생성하는 시뮬레이션으로 보다 빠른 시간내에 작업공간 구성과 작업 특성을 생성하여 최적화된 자원을 구성한 결과를 물리시스템으로 전송함으 로써 제조 프로세스의 지속적 개선이 가능한 것으로 파악되었다.

This study proposes a digital twin implementation method through simulation so that the manufacturing process can be optimized in a manual manufacturing site. The scope of the proposal is a knowledge management mechanism that collects manual motion with a sensor and optimizes the manufacturing process with repetitive experimental data for motion recognition. In order to achieve the research purpose, a simulation of the distribution site was conducted, and a plan to create an optimized digital twin was prepared by repeatedly experiencing the work simulation based on the basic knowledge expressed by the worker's experience. As a result of the experiment, it was found that it is possible to continuously improve the manufacturing process by transmitting the result of configuring the optimized resources to the physical system by generating the characteristics of the work space configuration and working step within a faster time with the simulation that creates the digital twin.

Current physics-based simulation is an important tool in the fluid animation. However some problems require a new change to current research trends which depend only on the simulation. The ultimate goal of this project is to obtain information of flow example, analyze an example through machine learning and the novel fluid animation reconfigure without physical simulation.

Governments, companies, universities and research institutes are pushing the research and development of cyber-physical systems (CPS). However, the development of cyber-physical systems is constrained by security factors. According to this situation, this paper put forward a CPS security model, which contains security objectives, basic theories, simulation, and CPS framework, summarizes security attacks to cyber-physical systems as a theoretical reference for the study of cyber–physical systems and to provide useful security defense. Based on the cyber-physical systems framework, the paper classifies attacks for the execution layer, transport layer and control layer. The execution layer attacks include security attacks for nodes such as sensors and actuators. Transport layer attacks include data leakage or damage and security issues during massive data integration. Control layer attacks include the loss of user privacy, incorrect access control policies and inadequate security standards. This paper gives security defenses and recommendations for all types of security attacks. Finally, this paper introduces categorizations of CPS application fields and explores their relationships.

At present, the higher education pays more attention to the improvement of the teaching quality, not the scale expansion. Constructing the scientific, reasonable evaluation index system of college physical education teaching is the basis and prerequisite for the education administrative department to launch the appraisal work. The rapid development of the computer technology not only brings the convenience in the daily life, but also provides the new ideals and methods for the college physical education teaching evaluation. The combination between the college physical education teaching evaluation and the computer technology becomes the development trend in current college physical education evaluation work. AHP method is an important assessment method. However, in traditional AHP method, human subjectivity may cause a certain impact on the assessment results. In this paper, we propose the Fuzzy AHP-Entropy method. This method can reduce the influence of the human subjectivity on the results. We apply this method to college physical education teaching evaluation. Then we use the computer simulation to obtain the evaluate results. Finally, the computer simulation experiment shows that the method is scientific, operability and efficient.

본 조사는 2013년 6월부터 8월까지 금강 상류에서 멸종위기야생생물 I급인 두드럭조개 (Lamprotula coreana)의 서식지를 조사하였다. 서식지 평가를 위하여 하천의 물리적 구조인 여울, 소 및 유수역이 모두 포함된 다양한 서식환경에서 서식상태를 조사하였으며, 하천단면, 수심, 유속, 하상재료 및 서식지 유형 등을 현장에서 측정 하였다. 서식 확인된 두드럭조개는 크기, 무게 및 연령을 기록하고 서식지에 재살포하였고, 서식지적합도지수 (Habitat suitability index, HSI)와 PHABSIM (physical habitat simulation system)에 의한 최적 생태유량 산정을 위하여, 각각의 채집 장소에서 수심, 유속 및 하상재료 등을 기록하였다. 서식지 평가는 수위, 유량 및 하천단면의 현장조사 결과와 두드럭조개의 HSI를 PHABSIM에 적용하여 가용서식지면적 (weighted usable area, WUA)과 유량의 관계 곡선을 작성하였다. 금강 상류에서 채집된 두드럭조개는 각장 $73.1{\pm}18.4mm$ 및 전중 $131.6{\pm}72.3g$ 이었으며, 연령은 2-7년생까지 서식하는 것으로 확인되었다. 두드럭조개의 HSI는 수심 0.4-0.5 m, 유속 0.3-0.5 m/s, 하상재료는 모래-호박돌로 나타났다. PHABSIM에 의해 모의된 최적유량은 2.1 cms였으며, WUA는 $3,730m^2$/1000 m로 나타났다. 두드럭조개의 서식지 평가 결과는 최근 각종 하천 공사 및 생태적 교란 등으로 서식 범위가 감소하고 있는 시점에서 서식지 복원 및 관리를 위한 기초자료로 활용될 수 있을 것이다.

This study sampled endangered species, Lamprotula coreana, and surveyed its habitat at the Guem River with three times from June to August 2013. To assess the habitat, this study conducted field survey considering diverse physical conditions of stream, such as pool, run and riffle, and measured transect, water depth, water velocity, substrate structure, and habitat type. When L. coreana collected, length, weight and age were measured. Water velocity, water depth and substrate structure were recorded to develop HSI (habitat suitability index) and performed PHABSIM (physical habitat simulation) to estimate the optimum flow discharge. Water level, flow discharge and transect data were used for habitat assessment, and PHABSIM was applied to calculate WUA (weighed usable area). Shell length was $73.1{\pm}18.4mm$ (28.5-102.0 mm), shell weight was $131.6{\pm}72.3g$ (28.0-281.0 g) and age was two to seven years from L. coreana collected at the upstream of the Guem River. Developed HSI indicated that the optimal habitat for L. coreana was 0.4-0.5 m for water depth, 0.3-0.5 m/s for water velocity and sand to boulder for substrate structure. The optimum ecological flow discharge for L. coreana was 2.1 cms and WUA was $3,730m^2$/1000 m by the result of PHABSIM. Recently, river construction work and habitat disturbance have caused negative impact on the distribution of L. coreana. The result of this study would provide fundamental data for habitat restoration and management of L. coreana.

본 연구에서는 한국 낙동강에 위치한 강정-고령보에 설치된 by-pass 어도의 유인효율을 유량 변화에 따라 살펴보고, 어도 유인효율을 극대화할 수 있는 최적의 본류 방류량을 산정하였다. 강정-고령보는 고정보와 가동보로 구성된 혼합식 보로 유량조절이 가능하며, 가동보의 조작에 따라 by-pass 어도 내의 유량이 결정된다. 유인효율의 지표로 목표어종의 HSC(Habitat Suitability Criteria) 지수에 기반한 WUA(Weighted Usable Area)를 삼았다. WUA는 평면 2차원 물리서식처 모형인 River2D를 활용하여 계산하였다. 또한 River2D로 계산된 유속장은 GPS Floater를 활용한 현장관측 자료로 검증하였으며, 어망을 이용한 월별 어류 모니터링 자료로 유인효율 평가의 타당성을 간접적으로 검증하였다. 결과적으로 본 연구 대상인 강정-고령보의 by-pass 어도에서 가장 효과적으로 목표 어류를 유인하기 위해서는 본류의 유량이 190 cms내외를 유지해야 한다. 특히 목표 어류인 모래무지가 봄철(4월~6월)에 산란기를 맞아 상하류로 이동하려는 경향을 띄므로, 이때 적절한 가동보 운영을 통해 본류 유량을 190 cms로 유지하는 것이 필요하리라 사료된다.

Through analysing the influence of steam flow direction on the liquid formation and motion behavior in the condenser shell side, the physical model for existing numerical simulation program of condenser is improved by introducing the correlations for flow resistance and condensation heat exchange coefficient in which the influences of steam flow direction are considered according to the available experimental data. Thus a more suitable and general condenser simulation approach is presented and a new condenser calculation program is developed. With the experimental data of a pannier- arrangement experimental condenser, the adaptability of the new condenser simulation approach is verified. General characteristics of this type of condenser are also revealed.

Objectives: Intraoperative navigation reduces the risk of major complications and increases the likelihood of optimal surgical outcomes. This paper presents an augmented reality (AR)-based simulation technique for ventriculostomy that visualizes brain deformations caused by the movements of a surgical instrument in a three-dimensional brain model. This is achieved by utilizing a position-based dynamics (PBD) physical deformation method on a preoperative brain image.Methods: An infrared camera-based AR surgical environment aligns the real-world space with a virtual space and tracks the surgical instruments. For a realistic representation and reduced simulation computation load, a hybrid geometric model is employed, which combines a high-resolution mesh model and a multiresolution tetrahedron model. Collision handling is executed when a collision between the brain and surgical instrument is detected. Constraints are used to preserve the properties of the soft body and ensure stable deformation.Results: The experiment was conducted once in a phantom environment and once in an actual surgical environment. The tasks of inserting the surgical instrument into the ventricle using only the navigation information presented through the smart glasses and verifying the drainage of cerebrospinal fluid were evaluated. These tasks were successfully completed, as indicated by the drainage, and the deformation simulation speed averaged 18.78 fps.Conclusions: This experiment confirmed that the AR-based method for external ventricular drain surgery was beneficial to clinicians.

Many papers have studied computer simulations of elastic bodies undergoing large deflections and large deformations. But there have not been many attempts to check the validity of the numerical formulations because the simulation results could not be matched without correct input data such as material properties and damping effects. In this paper, these values are obtained from real experiment with a high-speed camera and a data acquisition system. The simulation results with the absolute nodal coordinate formulation (ANCF) are compared with the results of real experiments. Two examples, a thin cantilevers beam and a thin plate, are studied to verify whether the simulation results are well matched to experimental results.

In order to meet the thermal performance analysis accuracy requirements of high density permanent magnet synchronous motor (PMSM), a method of multi physical domain coupling thermal analysis based on control circuit, electromagnetic and thermal is presented. The circuit, electromagnetic, fluid, temperature and other physical domain are integrated and the temperature rise calculation method that considers the harmonic loss on the frequency conversion control as well as the loss non-uniformly distributed and directly mapped to the temperature field is closer to the actual situation. The key is to obtain the motor parameters, the realization of the vector control circuit and the accurate calculation and mapping of the loss. Taking a 48 slots 8 poles high density PMSM as an example, the temperature rise distribution of the key components is simulated, and the experimental platform is built. The temperature of the key components of the prototype machine is tested, which is in agreement with the simulation results. The validity and accuracy of the multi physical domain coupling thermal analysis method are verified.

As the remote sensing satellite technology grows, the acquisition of accurate attitude and position information of the satellite has become more and more important. Due to the data processing limitation of the on-board orbit propagator and attitude determination algorithm, it is required to develop much more accurate orbit and attitude determination, which are so called POD (precision orbit determination) and PAD (precision attitude determination) techniques. The sensor and attitude dynamics simulation takes a great part in developing a PAD algorithm for two reasons: 1. when a PAD algorithm is developed before the launch, realistic sensor data are not available, and 2. reference attitude data are necessary for the performance verification of a PAD algorithm. A realistic attitude dynamics and sensor (IRU and star tracker) outputs simulation considering their physical characteristics are presented in this paper, which is planned to be used for a PAD algorithm development, test and performance verification.

Since bushing components have highly nonlinear characteristics according to the amplitude and the frequency, it is hard to derive a mathematical modeling of the bushing. In this paper, a semi-physical bushing model and a black-box bushing model are derived and compared. A Bouc-Wen hysteretic model is employed to derive a semi-physical model and an artificial neural network algorithm is used to make a black-box bushing model. A 3-axes MTS rubber test machine is used to capture the bushing characteristics. Sine excitation tests based on the different frequencies and different amplitudes are performed to find out the bushing characteristics. Random test results are also used to generate the coefficients of a semi-physical model and weighting factors of the black-box model. Random simulations are carried out to verify the bushing models and the results are compared with each other according to the numerical efficiency and accuracy.

Simulation tools are actively used for various purposes of building energy analysis and evaluation and related research. Simulation tools provide built-in physical properties information of the building materials used in the building at the modeling stage to simulate the structure. However, this physical properties information database has practical usability problems such as diversity of measurement values, errors due to different unit values, and not covering new materials. Although such problems can be solved by accessing big data, there are not many studies on this way, and especially, there is no study on the physical properties of building materials. These problems can be solved by collecting actually measured physical properties of building materials, collecting physical properties information of website, and building a new database of building materials properties so this database is more diverse than the database embedded in the simulation tools and can be applied to diverse format of the simulation tools. The purpose of this study is to construct a web crawler based on Python language for effective use of simulation tools and to construct an information gathering algorithm for building new applicable material properties information. As a result of designing the data collection algorithm, it was able to automatically collect vast amounts of data on the website, filter unnecessary data, and convert it into a file of the applicable format. The result of this algorithm design can easily collect a large amount of data and apply it to the simulation tool, and it will be able to overcome the limitation of the database embedded in the simulation tools

After we made the computer source code with mathematical model of Muramatsu et al. that was expressed by the set of simultaneous first-order ordinary differential equations in evaporation-pyrolysis zone of cigarette, we simulated the distribution profiles of temperature and density of flue-cured tobacco. Those equations were solved numerically with the Runge-Kutta-Gill algorithm assuming step size of 0.025mm by Muramatsu at at,, but in this study the advanced algorithm of Runge-Kutta 4th Order assuming step size of 0.0005mm. The initial conditions and physical parameters of Muramatsu et at. were used for solving them. The calculated values corresponded well with results of Muramatsu et al., especially the gradient of the temperature profile increased with smoldering speed and the thickness of the evaporation-pyrolysis zone decreased with increasing of smoldering speed. On the other hand, the temperature gradient decreased with increasing of the effective thermal-conductivity value and the thickness of the evaporation-pyrolysis zone increased with the effective thermal-conductivity value.