• Biomedical Engineering Letters
• /
• 제8권4호
• /
• pp.383-392
• /
• 2018

For prompt gamma ray imaging for biomedical applications and environmental radiation monitoring, we propose herein a multiple-scattering Compton camera (MSCC). MSCC consists of three or more semiconductor layers with good energy resolution, and has potential for simultaneous detection and differentiation of multiple radio-isotopes based on the measured energies, as well as three-dimensional (3D) imaging of the radio-isotope distribution. In this study, we developed an analytic simulator and a 3D image generator for a MSCC, including the physical models of the radiation source emission and detection processes that can be utilized for geometry and performance prediction prior to the construction of a real system. The analytic simulator for a MSCC records coincidence detections of successive interactions in multiple detector layers. In the successive interaction processes, the emission direction of the incident gamma ray, the scattering angle, and the changed traveling path after the Compton scattering interaction in each detector, were determined by a conical surface uniform random number generator (RNG), and by a Klein-Nishina RNG. The 3D image generator has two functions: the recovery of the initial source energy spectrum and the 3D spatial distribution of the source. We evaluated the analytic simulator and image generator with two different energetic point radiation sources (Cs-137 and Co-60) and with an MSCC comprising three detector layers. The recovered initial energies of the incident radiations were well differentiated from the generated MSCC events. Correspondingly, we could obtain a multi-tracer image that combined the two differentiated images. The developed analytic simulator in this study emulated the randomness of the detection process of a multiple-scattering Compton camera, including the inherent degradation factors of the detectors, such as the limited spatial and energy resolutions. The Doppler-broadening effect owing to the momentum distribution of electrons in Compton scattering was not considered in the detection process because most interested isotopes for biomedical and environmental applications have high energies that are less sensitive to Doppler broadening. The analytic simulator and image generator for MSCC can be utilized to determine the optimal geometrical parameters, such as the distances between detectors and detector size, thus affecting the imaging performance of the Compton camera prior to the development of a real system.

• 방사성폐기물학회지
• /
• 제15권4호
• /
• pp.333-341
• /
• 2017

원자력 발전 이후에 누적되는 사용후핵연료를 해소하기 위한 다양한 연구가 시도되고 있으며, 특히 건식으로 사용후핵연료를 재활용하는 파이로 공정이 주목되고 있다. 파이로 공정의 공학규모 실증을 위하여 대형 공정셀을 구비한 PRIDE 시설이 구축되었다. 파이로 공정에 사용되는 용융염의 화학반응성을 고려하여, 공정셀 내부는 아르곤 분위기를 유지한다. 결과적으로, 작업자가 공정셀 내부에 진입할 수 없으며, 공정셀 내부에 설치된 모든 공정장치는 원격수단에 의해 공정셀 밖에서 원격조작을 통해 수행한다. 따라서, 공정셀에 설치되는 공정장치는, 설계단계에서 부터 원격작업을 고려하여 설계되어야 하며, 공정셀에 반입하기 전에 원격으로 작동이 가능한지 철저히 검증하여야 한다. 만약, 공정셀에 반입되어 작동하는 단계에서 문제가 발생하는 경우, 장치를 반출하여 수정한 후 재반입하기까지 많은 비용과 시간을 허비하게 된다. 공정장치의 원격성 검증을 위하여, 물리적인 목업을 사용할 뿐 아니라, 설계단계에서 3D 모델을 활용한 가상 검증이 가능하다. 본 연구는, 가상공간에 PRIDE 공정셀을 구성하고, 설계된 공정장치 3D 모델을 입력하여, 원격조작성을 검증하기 위한 PRIDE 3D 시뮬레이터 개발에 관한 것이다. 실제 PRIDE 공정셀의 형상과 공정셀에 설치되는 원격운전 및 유지보수 장치의 움직임을 가상공간에 구현하고, 공정장치의 3D 모델을 실제 설치할 장소에 위치할 수 있도록 하였다. PRIDE 공정셀에 설치될 전해공정장치의 전극교체 작업을 시뮬레이션 시나리오로 설정하여, 개발된 PRIDE 3D 시뮬레이터의 사용성을 검증하고자 하였다. 8단계로 이루어진 원격작업 시나리오를 구성하여, 각 단계의 원격작업을 성공적으로 모사함으로써, PRIDE 공정셀의 원격성 평가를 성공적으로 수행하였다.

• 동력기계공학회지
• /
• 제12권6호
• /
• pp.36-41
• /
• 2008

A crane is very important mechanical systems in industrial applications to move huge objects. Especially, in marine port terminals, it is used to place container boxes at desired position within given operating time. However, such system is faced with environmental disturbance such as wind from the sea, thus crane control system is required to cope with this nature. This paper proposed robust and adaptive control algorithm of a complicated 3D crane against the environmental disturbance. We simplify a mathematical design procedure to derive our control algorithm. We conduct real-time experiment using a crane simulator to evaluate its superiority and reliability.

• 대한기계학회논문집A
• /
• 제28권8호
• /
• pp.1116-1124
• /
• 2004

In these days, a vehicle simulator has been developed with a VR(Virtual Reality) system. A VR system must provide a vehicle simulator with natural interaction, sufficient immersion and realistic images. In addition, a VR system must present a driver with the realistic driving situation. To achieve these, it is important to obtain a fast and uniform rendering performance regardless of the complexity of virtual worlds. In this paper, the factors to improve the reality for the VR based vehicle simulator have been investigated. For the purpose, the modeling and the rendering methods which offer an improved performance for complex VR applications as the 3D road model have been implemented and verified. Then, we experiment on the influence of graphic and sound factors to the driver, and analyze each result for improving the reality such as the driver's viewport, the form of texture, the lateral distance of the side object, and the sound effect. These factors are evaluated on the driving system which is constructed for qualitative analysis. The research results could be used for improving the reality of the VR based vehicle simulator.

• 한국컴퓨터정보학회논문지
• /
• 제20권4호
• /
• pp.49-56
• /
• 2015

본 논문에서는 3D 애니메이션 도구인 마야를 이용하여 태양계를 모델링하고 각 행성의 움직임과 물리적인 속성들을 정밀하고 객관적으로 구현하여 태양계의 구조를 시각적으로 쉽게 이해할 수 있도록 시뮬레이터를 구현하였다. 메뉴를 이용한 마야의 모델링으로는 정밀한 물리적 속성 값을 표현하기 어려우므로 파이선 스크립트를 이용하여 각 행성의 특성을 표현하였다. 제안하는 시뮬레이터는 가상현실 분야나 학생들의 교육 자료로서 사용 가능하도록 모델링과 렌더링을 실사와 동일하게 구현하였다. 또한 마야 애니메이션에서의 메뉴를 이용한 모델링과 스크립트 언어인 파이선을 활용하여 누구라도 쉽게 실사 영상을 볼 수 있도록 하였다.

• 한국멀티미디어학회논문지
• /
• 제22권9호
• /
• pp.1122-1131
• /
• 2019

This paper covers research on terrain construction for unmanned aerial vehicle simulators using spatial information that was distributed by public institutions. Aerial photography, DEM, vector maps and 3D model data were used in order to create a realistic terrain simulator. A data converting method was suggested while researching, so it was generated to automatically arrange and build city models (vWorld provided) and classification methods so that realistic images could be generated by 3D objects. For example: rivers, forests, roads, fields and so on, were arranged by aerial photographs, vector map (land cover map) and terrain construction based on the tile map used by DEM. In order to verify the terrain data of unmanned aircraft simulators produced by the proposed method, the location accuracy was verified by mounting onto Unreal Engine and checked location accuracy.

• 한국전자파학회논문지
• /
• 제17권3호
• /
• pp.229-238
• /
• 2006

본 논문에서는 3-D 시뮬레이터를 이용하여 아이솔레이터의 공진기를 설계하고 변화에 대한 factor를 이용하여 단순화된 시뮬레이션 방식을 제안하고 그에 따른 제품의 특성 값을 비교하고자 하였다. 3차원 유한요소법(FEM)을 이용한 소프트웨어로 중심 주파수가 1.85 GHz 대역인 스트립라인을 설계하여 변수를 확인하였으며, 최종 최적화된 스트립라인과 상용화되어 있는 페라이트를 이용하여 삽입 손실, 0.2 dB 이하, 반사 손실과 격리도가 25 dB 이상인 아이솔레이터를 개발하였다. 시뮬레이션 결과와 비교하여 90 % 이상 일치하는 것을 확인할 수 있었다.

• 대한조선학회논문집
• /
• 제55권4호
• /
• pp.361-369
• /
• 2018

The ship surveyor makes a scheme of reasonable ship operation by examining whether the ship has been properly constructed in accordance with the rule of classification societies and international conventions or whether the facilities of the ship in operation meet the standard stipulated by law. Even though the ship surveyors of classification society generally consist of people who have the skill of design or operation of a ship, it takes a long time to train a surveyor to the maturity level. This paper describes the development of survey simulator based on virtual ship environment that enables the surveyor minimize trial and errors to survey the ships. By using VR(Virtual Reality) based survey simulator, surveyors possibly achieve improvement of competence in survey quality by means of safe and immersive training environment. In order to improve the usability and utility of the VR simulator, the ship 3D model has been generated using 3D CAD model for design and production in shipyard. Through this, we suggested the possibility of consistent use of 3D model as the digital twin of a ship.

• 한국CDE학회논문집
• /
• 제16권3호
• /
• pp.227-235
• /
• 2011

Ship handling simulator should have capabilities of calculating ship motions (heave, pitch, and roll) at given sea state and displaying the calculated motions through a real-time 3D visualization system. Motion solver of a ship handling simulator generally calculates those motions in addition to position for an own ship, a main simulation target, but provides only position information for traffic ships. Therefore, it is required to simulate real-time traffic ship and buoy motions coupled with ocean waves in a ship handling simulator for the realistic visualization. In the paper, the authors propose a simple dynamics model by which ship and buoy motions are calculated with the input data of wave height and discuss a method for the implementation of a ship and buoy motions calculation module.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2002년도 ICCAS
• /
• pp.68.6-68
• /
• 2002

$\textbullet$ We solved the attitude regulation and tracking problems of spacecrafts. $\textbullet$ We developed a PC-based 3D spacecraft simulator using OpenGL. $\textbullet$ We considered the rigid spacecrafts with gas-jet and reaction wheel actuator. $\textbullet$ In order to verify the effectiveness of the simulator, we applied the output-based controller $\textbullet$ Spacecraft models are animated by roll-pitch-yaw angles, constantly processed by numerical method.