• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2014년도 춘계학술대회
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• pp.36-37
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• 2014

It is necessary to develop highly sophisticated Modeling & Simulation (M&S) system for the scientific investigation of marine accident causes and for the systematic reproduction of accidental damage procedure. To ensure an accurate and reasonable prediction of marine accidental causes, such as collision, grounding and flooding, full-scale ship M&S simulations would be the best approach using hydrocode, such as LS-DYNA code, with its Fluid-Structure Interaction (FSI) analysis technique. The objectivity of this paper is to present three full-scale ship collision, grounding and flooding simulation results of marine accidents, and to show the possibility of the scientific investigation of marine accident causes using highly sophisticated M&S system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.152-157
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• 1995

The electron transport coefficients in $SP_{6}$ gas is calculated and analysed for range of E/N values from 150∼800(Td) by a Monte Carlo simulation, using a set of electron collision cross sections determined by the authors. The result of the Monte Carlo simulation such as electron drift velocity, ionization and electron attachment coefficients, longitudinal and transverse diffusion coefficients in neatly agreement with the respective experimental and theoretical for a range of E/N. The validity of the results obtained has been confirmed by a Monte Carlo simulation carried out parallel to the analysis.

• Journal of Mechanical Science and Technology
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• 제19권4호
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• pp.976-984
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• 2005

This paper presents the analysis results of dynamics in the billiards game within the frame­work of rigid-body mechanics and a numerical simulation program. The friction exists between the ball and the table bed as well as between the ball and the rail. There are three parts in the dynamic behavior of the ball on the table bed; motion of the ball on the table bed, collision between balls, and collision between the ball and the cushion. During the development of the simulation program, the dynamics problems such as rolling motion and three-dimensional frictional impact motion have been analyzed in detail. The theoretical issues are implemented into a viable graphic simulation program and its efficacy is demonstrated through the experi­mental validation of the billiards game. The resulting analysis results are verified quantitatively and qualitatively using high-speed video camera. Through the experimental tests, it was found that the physical parameters such as coefficients of restitution and friction vary according to the motion variables and corresponding empirical formulations were developed. The simulation and experimental results agree well.

• 전기학회논문지P
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• 제63권1호
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• pp.19-23
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• 2014

This paper describes the electron transport characteristics in $SF_6$-He gas calculated E/N values 0.1~700[Td] by the Monte Carlo simulation and Boltzmann equation method using a set of electron collision cross sections determined by the authors and the values of electron swarm parameters obtained by TOF method. This study gained the values of the electron swarm parameters such as the electron drift velocity, the electron ionization or attachment coefficients, longitudinal and transverse diffusion coefficients for $SF_6$-He gas at a range of E/N. A set of electron collision cross section has been assembled and used in Monte Carlo simulation to predict values of swarm parameters. The result of Boltzmann equation and Monte Carlo Simulation has been compared with experimental data by Ohmori, Lucas and Carter. The swarm parameter from the swarm study are expected to sever as a critical test of current theories of low energy scattering by atoms and molecules.

• 대한기계학회논문집B
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• 제28권12호
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• pp.1494-1500
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• 2004

A zero-dimensional direct simulation Monte Carlo(DSMC) model is developed for simulating diatomic gas including vibrational kinetics. The method is applied to the simulation of two systems: vibrational relaxation of a simple harmonic oscillator and translational-rotational-vibrational energy exchange process under heating and cooling. In the present DSMC method, the variable hard sphere molecular model and no time counter technique are used to simulate the molecular collision kinetics. For simulation of diatomic gas flows, the Borgnakke-Larsen phenomenological model is adopted to redistribute the translational and internal energies.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.890-903
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• 2017

The problem of determining a smooth and collision-free path with maximum possible speed for a Mobile Robot (MR) which is chasing a moving target in a dynamic environment is addressed in this paper. Genetic Network Programming with Reinforcement Learning (GNP-RL) has several important features over other evolutionary algorithms such as it combines offline and online learning on the one hand, and it combines diversified and intensified search on the other hand, but it was used in solving the problem of MR navigation in static environment only. This paper presents GNP-RL based on predicting collision positions as a first attempt to apply it for MR navigation in dynamic environment. The combination between features of the proposed collision prediction and that of GNP-RL provides safe navigation (effective obstacle avoidance) in dynamic environment, smooth movement, and reducing the obstacle avoidance latency time. Simulation in dynamic environment is used to evaluate the performance of collision prediction based GNP-RL compared with that of two state-of-the art navigation approaches, namely, Q-Learning (QL) and Artificial Potential Field (APF). The simulation results show that the proposed GNP-RL outperforms both QL and APF in terms of smooth movement and safer navigation. In addition, it outperforms APF in terms of preserving maximum possible speed during obstacle avoidance.

• 한국철도학회논문집
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• 제14권4호
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• pp.333-340
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• 2011

본 논문은 유럽 TSI와 국내철도차량안전기준에 정의된 건널목 충돌사고시나리오에서 요구하는 성능의 대형 변형체 장애물의 유한요소 모델에 대하여 2가지 종류의 모델을 개발하여 한국형 분산형 고속철도 차량에 적용하고 평가하였다. 규정에서 요구하는 대형 장애물은 기존 강체모델에서 현재의 변형체모델로 변경되었으며 규정에 정의된 방법으로 변형체 강성 값이 검증되어야 한다. 여러 번의 시뮬레이션을 통해 기준을 만족하는 균일한 밀도와 강성의 솔리드 형 장애물 모델과 균일하지 않은 셸 형 장애물 모델 등 2가지를 개발하였다. 본 연구에서 개발된 대형장애물을 사용하여 분산형 고속열차를 대상으로 규정의 대형장애물 충돌시뮬레이션을 수행하였고 그 결과를 평가하였다. 셸 형과 솔리드 형 장애물은 열차와 충돌 후 거동에 상당한 차이가 있었고, 셸 모델이 더 가혹한 결과를 나타내었다.

• 대한조선학회논문집
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• 제55권3호
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• pp.236-242
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• 2018

Damage due to ice collision is the most serious threat for the structural safety of ships operating in arctic region. Since such hull damages are usually caused by the collision of floating ice at excessive voyage speed of ships, the authorities responsible for the shipping at arctic sea are required to provide the speed limit for safe voyage, so-called safe speed. In countries near arctic ocean, such as Canada and Russia, empirical methods to determine the safe speed of ships based on their long experience of arctic voyage have been established and applied them in the real arctic navigation. However, in Korea, it is not easy to accumulate the arctic voyage experience and related technical database, so it seems to be a realistic approach to adopt a safe voyage speed estimating method in arctic sea based on the ice collision simulation technology using the nonlinear finite element analysis. The aim of this study is to develop a technique for estimating the safe voyage speed of vessels operating at arctic sea through the ice collision analysis, In order to achieve this goal, the standard procedure of the ice collision analysis is dealt with and example analysis was carried out and the results were considered. To investigate the validity of developed method, POLARIS system proposed by IMO was studied for comparison.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2003년도 춘계공동학술대회논문집
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• pp.81-86
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• 2003

일본을 중심으로 과거 10여년전부터 수행되어온 선박자동충돌회피연구는 최근 눈부신 IT산업의 발전에 힘입어 실용화 단계에 까지 접어들 수 있는 환경을 맞이 하고 있다. 본 논문에서는 이러한 연구의 일환으로 선박자동충돌회피지원시스템의 주요 핵심 기술인 자동회피 알고리즘을 구성하기 위한 연구를 수행하였다. 선박운동방정식은 간편히 선체운동을 수학식으로 표현하는 KT모델을 이용하였으며, 선박이 정해진 항로를 유지해 나가는 Track Control System의 구현을 위해서는 퍼지 이론을 이용한 자동제어 시스템을 적용하였다. 또한 충돌회피 추론 부분에서는 위험도 판정을 위하여 TCPA와 DCPA를 이용한 퍼지 추론이 이용되었다. 충돌회피거동 기능면에서는 국제해상충돌예방규칙을 기초로 하여, 두 선박의 다양한 조우 상황을 분석하였다. 이 분석에 기초한 피항거동이 이루어질수 있도록 알고리즘을 구축하였다. 제안된 시스템의 유효성을 검증하기 위하여, 다양한 상황의 시뮬레이션이 수행되었다. 그 결과 적절한 선박충돌회피 동작이 이루어지는 것을 확인하였으며, 향후 더욱 연구가 발전된다면 자동선박충돌회피지원시스템으로 실 선박에 적용할 수 있는 가능성을 확인하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2009년도 추계학술대회
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• pp.62-63
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• 2009

인적 오류를 줄이고, 해상교통관제를 효과적으로 지원하기 위해 다중선박의 충돌 위험도를 모니터링할 수 있는 시스템을 개발하였다. 다중선박 충돌위험도 추정 알고리즘은 선박들의 항행정보로서 AIS 정보를 이용할 수 있도록 고안되었다. 선박들의 현재와 미래의 경로를 고려하기 위하여, 퍼지알고리즘을 이용하여 충돌위험도가 계산되도록 구성하였다. 고안된 새로운 알고리즘의 성능을 검증하기 위해 선박운항 시뮬레이터기반 재생시뮬레이션을 수행하였다. 이를 위해, 울산항만의 해상교통관제 (VTS) 센터로부터 AIS 정보를 수집하여 데이터베이스를 구축하였다. 수집된 데이터는 약 2시간 동안 실제로 울산항만에서 운행된 25척의 선박들의 항행데이터를 포함하고 있다. 본 논문에서는 새로 개발된 선박충돌 위험도 추정알고리즘의 특정과 재생시뮬레이션 결과들에 대해 소개한다.