• Geophysics and Geophysical Exploration
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• v.14 no.1
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• pp.98-104
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• 2011

Numerical simulation in exploration geophysics provides important insights into subsurface wave propagation phenomena. Although elastic wave simulations take longer to compute than acoustic simulations, an elastic simulator can construct more realistic wavefields including shear components. Therefore, it is suitable for exploration of the responses of elastic bodies. To overcome the long duration of the calculations, we use a Graphic Processing Unit (GPU) to accelerate the elastic wave simulation. Because a GPU has many processors and a wide memory bandwidth, we can use it in a parallelised computing architecture. The GPU board used in this study is an NVIDIA Tesla C1060, which has 240 processors and a 102 GB/s memory bandwidth. Despite the availability of a parallel computing architecture (CUDA), developed by NVIDIA, we must optimise the usage of the different types of memory on the GPU device, and the sequence of calculations, to obtain a significant speedup of the computation. In this study, we simulate two- (2D) and threedimensional (3D) elastic wave propagation using the Finite-Difference Time-Domain (FDTD) method on GPUs. In the wave propagation simulation, we adopt the staggered-grid method, which is one of the conventional FD schemes, since this method can achieve sufficient accuracy for use in numerical modelling in geophysics. Our simulator optimises the usage of memory on the GPU device to reduce data access times, and uses faster memory as much as possible. This is a key factor in GPU computing. By using one GPU device and optimising its memory usage, we improved the computation time by more than 14 times in the 2D simulation, and over six times in the 3D simulation, compared with one CPU. Furthermore, by using three GPUs, we succeeded in accelerating the 3D simulation 10 times.

• Journal of Astronomy and Space Sciences
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• v.20 no.4
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• pp.339-350
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• 2003

Engineering qualification model payload for a communications and broadcasting satellite(CBS) was developed by ETRI from May, 2000 to April, 2003. For. the purpose of functional test and verification of the payload, a real-time hardware-in-the-loop(HITL) CBS simulator(CBSSIM) was also developed. We assumed that the spacecraft platform for the CBSSIM is a geostationary communication satellite using momentum bias three-axis stabilization control technique based on Koreasat. The payload hardware is combined with CBSSIM via Power, Command and Telemetry System(PCTS) of Electrical Ground Support Equipment(EGSE). CBSSIM is connected with PCTS by TCP/IP and the payload is combined with PCTS by MIL-STD-1553B protocol and DC harness. This simulator runs under the PC-based simulation environment with Windows 2000 operating system. The satellite commands from the operators are transferred to the payload or bus subsystem models through the real-time process block in the simulator. Design requirements of the CBSSIM are to operate in real-time and generate telemetry. CBSSIM provides various graphic monitoring interfaces and control functions and supports both pre-launch and after-launch of a communication satellite system. In this paper, the HITL simulator system including CBSSIM, communications payload and PCTS as the medium of interface between CBSSIM and communications payload will be described in aspects of the system architecture, spacecraft models, and simulator operation environment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8116-8127
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• 2015

This study provides results from the experiment on the rainfall distribution using a large Experimental rainfall simulator with fixed nozzle arrangement. Results from the experiment on the nozzles which are crucial for rainfall simulation show standard errors expressed as percentage are 0.15~0.38% at the indoor flow testing apparatus and 0.37~0.59% at the KICT-ERS. To examine spraying range of the nozzles, radial and triangular rainfall measurement test are done. In the radial test, coefficient of uniformity (CU) lies in 0.348~0.657 in the single nozzle spraying case, while it increases up to 0.854~0.895 in the seven nozzle spraying case. This means increase of both rain rate and uniformity by means of superimposition of spraying. The CU of the triangular test falls to 0.845~0.896. The results from the experiment on the whole-scale of the KICT-ERS show that CU exceeds 0.7 for every case except the one experimental condition where a $1.5{\phi}$ nozzle is used. The CU tends to increase with increasing rainfall intensity. Comparison with the previous studies shows that KICT-ERS provides rainfall distribution above average CU.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.134-135
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• 2017

태양광 패널 등가모델을 결합한 태양광 발전 패널 모의 장치(SAS)는 정확도 면에서 많은 장점이 있다. 특히 SAS에서 사용되는 등가회로 모델은 주변 환경에 맞게 빠르게 변하는 I-V 출력특성을 추출하며, 추출시간이 짧다. 이러한 방법을 이용하려면 제어기를 주목해야하는데, 보통 전압 또는 전류 제어기 하나만 사용한다. 하지만 Fill factor가 높은 패널인 경우, 전압 또는 전류제어기 하나만 사용하여서는 제어가 잘 되지 않기 때문에 본 논문에서는 전압과 전류제어기 모두 사용하되, 필요에 따라 스위칭 하여 사용하는 하이브리드 제어기법을 제안한다. 이러한 기법을 통하여 모두 제어가 가능한 기법을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6A
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• pp.611-621
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• 2010

When an enemy platforms transmit electronic jamming or tracking interference signal to a friendly ship's radar, the radar have to avoid the jamming and to track targets continually without losing the targets with the electronic protection techniques. Electronic protection is an essential key for a platform to survive in electronic warfare, for this purpose, jamming simulator was developed to provide electronic warfare environments for the test and evaluate the effectiveness of radar's electronic protection techniques. Jamming simulator has ability to generate a variety of deception and noise jamming signals using the DRFM which minimize phase distortions of 1GHz broadband radar signal with the phase sampling method. This paper presents the design contents of the jamming simulator to process the analysis of broadband radar signal and generate jamming signal, also proposes the algorithms of the deception and noise jamming and verifies the effectiveness of the simulator by field trial.

• Journal of the Korea Society of Computer and Information
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• v.9 no.1
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• pp.63-70
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• 2004

This paper describes modeling, design and performance test results of infrared thermal image target system which can generate infrared thermal image on aircraft. The system is designed to control image shape and intensity so that the infrared image shape and its emitting intensity are so similar to that of real aircraft. When applying the technique suggested in this paper, the system consumes only small electric power energy about 30(㎾) to generate infrared thermal image which is equivalent to that of real aircraft under full power operation. After verifying performance test, the system developed here has been used as a target for korean potable surface to air missile(KPSAM) at the stage of evaluation test such as target adaptive guidance test and auto-pilot logic test.

• Journal of the Korean Society of Radiology
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• v.1 no.3
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• pp.11-16
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• 2007

In this study, the potential of a newly developed simulation toolkit, GATE for the simulation of electronic portal imaging devices (EPID) in radiation therapy was evaluated by characterizing the performance of the metal plate/phosphor screen detector for EPID. We compared the performances of the GATE simulator against MCNP4B code and experimental data obtained with the EPID system in order to validate its use for radiation therapy.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1724-1729
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• 2003

A new ground transportation system is often simulated by the wing in ground effect(WIG). Recently, several kinds of experimental and computational studies are being carried out to investigate the WIG aerodynamic characteristics which are of practical importance to develop the new ground transportation vehicle system. These works are mainly based on conventional wind tunnel tests, but many problems associated with the WIG aerodynamic characteristics can not be satisfactorily resolved. In order to develop the new ground transportation vehicle system the WIG should be further investigated. To do this, it is necessary to develop a s imulator appropriate to the WIG aerodynamics. The objective of the present study is to clarify the aerodynamic characteristics of the WIG and to develop a new experimental test rig for the investigation of the WIG aerodynamics. Some preliminary experiments are performed to investigate the usefulness of the WIG simulator.

• 연구논문집
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• s.28
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• pp.49-58
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• 1998

In order to analyse the scavenging efficiency in a poppet valve type 2-stroke engine. visualization of scavenging flow and quantitative experiments for measuring scavenging efficiency were performed. The effect of shroud angle in RSSV which was developed by KIMM was evaluated under steady flow rig applying single-cycle method. Also dynamic simulator was used by using gas sampling with $CO_2$ and $O_2$gas. The $90^circ$ shroud RSSV was found to be the highest efficient system, and single-cycle and dynamic simulator test are very effective to save time and cost for the development of a 2-stroke engine.

• Journal of Biomedical Engineering Research
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• v.21 no.6
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• pp.575-581
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• 2000

본 논문에서는 척추침생검 시뮬레이터에서 사용의 햅틱 디바이스인 PHANToM(sup)TM을 이용하여 사실적인 힘을 구현하는 방법을 보여준다. PHANToM(sup)TM은 툴의 끝부분에서 좌표축 방향으로만 힘을 낼 수 있는 단점이 있으며, 시스템의 구동장치의한계로 인하여 딱딱한 물체에 닿을 때 불안정한 특성을 보인다. 또한 좁은 영역 안에서 복잡한 조직들로 인한 급격한 강도 변화도 시스템의 불안정을 초래한다. 모사되는 힘은 두가지 성분으로 나뉜다. 하나는 바늘이 삽입될 때 바늘의 길이 방향으로 느껴지는 힘으로 생체 조직의 모델을 통해 값이 구해진다. 다른 하나는 바늘이 피부를 뚫고 지나간 이후에 바늘이 초기 삽입 방양을 유지 시켜주는 회전방향 힘으로 피봇을 이용하여 구현하였다. 불안정성 문제와 바늘이 튀어나오는 문제는 램핑 필터와 시간변수를 이용하여 제거하였다. 침생검 과정은 생체조직의 탄성 변형뿐 아니라 파괴가 일어나는 변형이므로 사실적인 힘을 구현하기 위해서 실험 데이터를 이용하여 삽입 깊이에 따라 탄성 계수와 마찰 상수가 변하는 모델을 제안하였다.