• Journal of the Korea Society for Simulation
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• v.18 no.2
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• pp.57-64
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• 2009

Stable and effective constraint enforcement system is one of the crucial components for physically-based dynamic simulations. This paper presents analysis and evaluation for traditional constraint enforcement systems(Lagrange Multiplier method, Baumgarte stabilization method, Post-stabilization method, Implicit constraint enforcement method, Fast projection method) to provide a guideline to users who need to integrate a suitable constraint enforcement system into their dynamic simulations. The mathematical formulations for traditional constraint enforcement systems are presented in this paper. This paper describes a summary of evaluation which consists of constraint error comparison, computational cost, and dynamic behavior analysis to verify the efficiency of each traditional constraint enforcement system.

• Proceedings of the Korean Institute of Landscape Architecture Conference
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• 2023.10a
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• pp.3-5
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• 2023

• Proceedings of the Korea Society for Simulation Conference
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• 2001.05a
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• pp.148-152
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• 2001

본 논문에서는 중대사고 해석코드인 MELCOR를 이용하여 개발중인 중대사고 훈련용 그래픽 시뮬레이터 MEL-GRS에 대하여 기술하였다. MEL-GRS는 SL-GMS 그래픽 튤과 MELCOR 계산 결과를 적절히 사용하여 중대사고 현상을 실시간으로 디스플레이하는 목적으로 개발되었는데, 기존의 MELCOR 코드에서 불가능했던 다이내믹 시뮬레이션 기능을 가지고 있어 실시간 밸브 및 펌프 조작이 가능하다. 개발된 시스템은 IBM PS Windows 환경에서 작동하며, 울진 3, 4호기를 대상으로 한 TLOFW, LOCA등의 중대사고 시나리오를 사용하여 그 성능을 검증하였다. 개발된 시스템은 차후 발전소 현장의 설치 및 검증을 거쳐 운전원 및 TSC 요원의 중대사고 훈련도구로 활용한 계획이다.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.04a
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• pp.189-191
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• 2016

실시간 물리 기반 3D 시뮬레이션에서 연산속도는 매우 중요한 요소이다. 객체의 움직임이나 변형과 같은 현상들은 복잡한 연산을 통해서 계산되기 때문에 일반적으로 시뮬레이션의 정확도와 연산속도는 반비례 관계에 있다. 현재 출시되고 있는 대부분의 게임에서는 물체의 움직임을 정확하게 표현하기보다 연산량을 줄이기 위해 물체의 움직임이나 변형을 비슷하게 표현하는데 중점을 두고 있다. 본 논문에서는 이러한 문제를 해결하기 위하여 OpenGL 4.3의 Compute shader를 사용하여 다이내믹 시뮬레이션의 연산 작업을 GPU 병렬처리로 처리하였다. Compute shader에서 파티클의 움직임을 계산하고 Shader storage buffer object에 저장하고 파티클들의 작업량을 적절한 Workgroup의 크기로 나누어 할당하여 최적의 처리속도를 제공하도록 구현하였다. Compute shader에서 파티클의 움직임을 표현하기 위해서 수치해법 중의 하나인 Euler method를 사용하였으며 실험 결과 파티클의 수가 4,194,304개일 때 CPU 방법에 비해 약 182배 빠른 연산속도 결과를 보였다. 추후 Compute shader를 활용하여 연산량이 많은 분야에 적용 가능할 수 있을 것으로 기대한다.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.5
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• pp.8-15
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• 2011

The goal of this paper is to describe how to construct an integrated simulation system that integrates limited perception-based mapping with spatial reasoning, path planning, and human motion style in order for a virtual soldier to effectively communicate with other virtual solders and/or human participants in a simulation. Virtual human research often ignores or simplifies perception by using a full map (with omniscient perception). In addition, previous research used a placement node where virtual environment designers save in advance the required information. However, this paper also shows that the human-like movement behavior can be achieved by the integrated ECA system with the mapping that supports a spatial understanding and does not require the omniscient perception.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.1
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• pp.16-21
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• 2002

In this paper, a dual type PFD(Phase Frequency Detector) for high speed PLL to improve output characteristics using TSPC(True Single Phase Clocking) circuit is proposed. The conventional 3-state PFD has problems with large dead-zone and long delay time. Therefore, it is not applicable to high-speed PLL(Phase-Locked Loop). A dynamic PFD with dynamic CMOS logic circuit is proposed to improve these problems. But, it has the disadvantage of jitter noise due to the variation of the duty cycle. In order to solve the problems of previous PFD, the proposed PFD improves not only the dead zone and duty cycle but also jitter noise and response characteristics by the TSPC circuit and dual structured PFD circuit. The PFD is consists of a P-PFD(Positive edge triggered PFD) and a N-PFD(Negative edge triggered PFD) and improves response characteristics to increase PFD gain. The Hspice simulation is performed to evaluate the performance of proposed PFD. From the experimental results, it has the better dead zone, duty cycle and response characteristics than conventional PFDs.

• Journal of Korea Multimedia Society
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• v.11 no.4
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• pp.516-524
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• 2008

This paper presents a new modeling technique for the simulation of cloth specific characteristics with a set of hard constraints using an implicit constraint enforcement scheme. A conventional explicit Baumgarte constraint stabilization method has several defects. It requires users to pick problem-dependent coefficients to achieve fast convergence and has inherent stabilization limits. The proposed implicit constraint enforcement method is stable with large time steps, does not require problem dependent feed-back parameters, and guarantees the natural physics-based motion of an object. In addition, its computational complexity is the same as the explicit Baumgarte method. This paper describes a formulation of implicit constraint enforcement and provides a constraint error analysis. The modeling technique for complex components of cloth such as seams, buttons, sharp creases, wrinkles, and prevention of excessive elongation are explained. Combined with an adaptive constraint activation scheme, the results using the proposed method show the substantial enhancement of the realism of cloth simulations with a corresponding savings in computational cost.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.106.2-106.2
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• 2010

IGCC (Integrated Gasification Combined Cycle) plants are among the most advanced and effective systems for electric energy generation. From a control perspective, IGCC plants represent a significant challenge: complex reactions, highly integrated control to simultaneously satisfy production, controllability, operability and environmental objectives. While all these requirements seem clearly to demand a multivatiable, model predictive approach, not many applications can be easily found in the literature. This paper describes the IGCC dynamic simulation that is capable of simulating plant startup, shutdown, normal, and abnormal operation and engineering studies. This high fidelity dynamic models contain the detailed process design data to produce realistic responses to process operation and upset. And the simulation is used by engineers to evaluate the transient performance and produce graphical information indicating the response of the process under study conditions.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10c
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• pp.630-632
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• 1998

큰 규모의 가상 환경에서 물체들은 사실적인 이미지효과와 함께 충돌 검출과 같은 다이내믹한 효과를 동반하여 더욱더 실제 물체와 같이 느껴지도록 해야한다. 특히, 가상세계에서의 충돌 검출은 실시간으로 계산되어야 한다. 가상환경을 이루는 기하학적 데이터의 양이 엄청나게 증가하면서 충돌 검출은 하나의 병목으로 극복되어야 할 문제로 여겨져 왔다. 본 논문에서는 많은 수의 복잡한, 3차원의 기하학적 모델들로 구성된 가상환경에서 단계적인 상세를 이용하여 가상 물체를 사실적으로 표현하면서도 어느 정도의 충돌 검출 병목을 해결하는 절충적인 방법을 제안하고 많은 양의 기하학적 데이터를 포함하는 토끼 모델을 사용하여 단계적인 상세를 이용한 가상환경을 구현하였다.

• Journal of Internet Computing and Services
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• v.18 no.3
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• pp.29-36
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• 2017

In these days, 3D dynamic simulation is closely related to many industries. In the past, physically-based 3D simulation was used mainly in the car crash or construction related fields, but it also plays an important role in movies or games today. Many mathematical computations are needed to represent the 3D object realistically, but it is difficult to process a large amount of calculations for simulation of application based on CPU in real-time. Recently, with the advanced graphic hardware and improved architecture, GPU can be utilized for the general purposes of computation function as well as graphic computation. Many approaches using GPU have been applied for various research fields. In this paper, we analyze the performance variation of two cloth simulation algorithms based on GPU according to the change of execution properties of GPU shaders in oder to optimize the performance of GPU-based cloth simulation. Cloth simulation is implemented by the spring centric algorithm and node centric algorithm with GPU parallel computing using compute shader of GLSL 4.3. We compare the performance of between these algorithms according to the change of the size and dimension of work group. The experiment is repeated to 10 times during 5,000 frames for each test and experimental results are provided by averaging of FPS. The experimental result shows that the node centric algorithm is executed in higher speed than the spring centric algorithm.