• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.103-107
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• 2001

When ship claps against the ocean structure sited at shallow water, the time simulation of motion responses of dolphin-moored ocean structure is presented. The equatien of motion based on Cummin's theory of impulse responses are employed, and solved in time domain by using the Newmark $\beta$ method. The added mass and damping coefficients involved in the equations are obtained from a three-dimensional panel method in the frequency domain. The impact forces due to ship collision are modeled as two method, and those are elastic and non-elastic collisions. The mooring forces for dolphin systems of scean structure are considered as linear spring system.

• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.114-119
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• 2002

본 논문에서는 자율 이동 로봇의 장애물에 대한 실시간 충돌 회피 동작의 문제에 대하여, 로봇이 장애물과 충돌하지 않는 안정적인 회피 동작과 유연한 궤적 생성, 그리고 효과적인 최적의 조향 동작을 계획할 수 있게 하기 위하여 레이저 스케닝 센서를 이용한 지역 장애물 회피 방법을 제안한다. 레이저 센서를 이용한 로봇의 안전한 방향 탐색은 자율 이동 로봇이 검출할 수 있는 최대의 검출 영역에서부터 로봇의 중심점을 향해 순차적으로 임계치를 줄여가는 동안 나타나는 무충돌 안전 구간과 충돌 구간을 정의함으로서 구성된다. 제안한 안전 방향 구간 탐색에 의한 로봇의 장애물 회피 동작의 성능 실험은 최적 방향의 탐색 성능을 평가하며, 실제의 이동 로봇을 이용하여 실험한 결과에 대하여 고찰하고 결론을 내린다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.17-17
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• 2008

3차원 입자 모델을 이용하여 $12\;mm{\times}625\;mm$ 크기의 평판형 마그네트론 스퍼터링용 음극에서 전자의 운동을 해석하였다. 전자와 중성 가스 입자의 충돌은 모두 세 가지를 고려하였으며 Runge-Kutta 4th order 방법을 이용하여 전자의 궤적을 계산하였다. 400 eV의 전자는 5 mTorr의 압력에서 알곤과 평균 8 - 12회 이온화 충돌 후 집중 방전 영역에서 벗어났으며 문헌에 보고된 2차원 실린더형 마그네트론에서 보고된 값보다 작았다. 마그네트론의 집중 방전 특성은 전자와 중성의 소각 산란에 의해서 주로 발생되었으며 이온화 충돌에 의해서 발생되는 2차 전자는 충돌 위치에서의 자기장 값에 의해서 궤적이 결정되었다.

• Annual Conference of KIPS
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• 2015.04a
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• pp.1018-1021
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• 2015

현대 사회는 개인작업보다 협업에 의한 작업들이 많다. 과거에는 컴퓨터와 개인 간의 작업이 대부분이었으나, 현재에는 스마트 폰과 태블릿의 급속한 보급으로 다자간의 협업체계로 시스템이 운용가능하게 되었다. 다자간의 협업체계로 운용되는 시스템은 기존의 개인 작업에서 발생하지 않았던 작업 충돌 현상이 발생할 수 있다. 이러한 작업 충돌 현상을 방지하기위한 방안을 제안하기위해 협업 드로잉 시스템을 제안한다. 이 시스템은 안드로이드 기반의 스마트 기기를 가진 사람들이 동시에 한 화변에 그림을 그리고, 그 그려진 그림화면을 공유하며 함께 작업을 진행한다. 이 시스템을 이용하는 사람들의 작업영역을 실시간으로 파악하여 서로간의 구두적인 의사소통 없이 작업 충돌을 최소화시키기 위한 방법에 대해 연구한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.171-171
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• 2022

해양사고는 매년 증가 추세이고 충돌사고 비율은 낮지만, 발생 시 대규모 피해로 있다. 특히, 3톤 미만 소형어선의 경우 바다네비게이션 서비스 등의 지능형해상교통서비스 관련 법규에서 제외되어 해양디지털화 및 해양사고의 사각지대에 놓여있다. 이에 따라, 본 연구에서는 3톤 미만의 소형선박의 환경에서 제공가능하도록 충돌예방에 기여할 수 있는 선박안전 충돌경보 이동형 단말장치 개발을 위하여 시제품을 개발하고, 소형선박 환경에서의 WAVE 기반 통신영역 실증 테스트를 수행함으로써 WAVE 통신기반 단말장치 활용 가능성을 확인하고 개선방안을 도출하였다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.1
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• pp.36-42
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• 2018

This paper considers the Marine Traffic Risk Assessment for fixed and moving targets, which threaten officers during a voyage. The Collision Risk Assessment Formula was calculated based on a dynamic ship domain considering the length, speed and maneuvering capability of a vessel. In particular, the Navigation Risk Assessment Model that is used to quantitatively index the effect of a ship's size, speed, etc. has been reviewed and improved using a hybrid combination of a vessel's dynamic area and the Collision Risk Assessment Formula. Accordingly, a new type of Marine Traffic Risk Assessment Model has been suggested giving consideration to the Speed Length Ratio, which was not sufficiently reflected in the existing Risk Assessment Model. The larger the Speed Length Ratio (dimensionless speed), the higher the CJ value. That is, the CJ value is presented well by the Speed Length Ratio. When the Speed Length Ratio is large, states ranging from [Caution], [Warning], [Dangerous] or [Very Dangerous] are presented from a greater distance than when the Speed Length Ratio is small. The results of this study, can be used for route and port development, including dangerous route avoidance, optimum route planning, breakwater width, bridge span, etc. as well as the development of costal navigation safety charts. This research is also applicable for the selection of optimum ship routing and the prevention of collisions for smart ships such as autonomous vessels.

• Proceedings of KOSOMES biannual meeting
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• 2005.11a
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• pp.15-20
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• 2005

Recently, ship collision accidents account for $20\%\∼30\%$ of domestic marine accidents, also have increased continually. In this paper, therefore we propose the development of Ship Collision Avoidance Support program for decreasing ship collision accidents. This program has been developed on the basis of CCAS-Model. A CCAS-Model has ship's maneuvering performance and has studied for the propose of supporting to avoid ship collision in close quarters. Besides, the program will effectively support maneuvering for collision avoidance through displaying the feasible area and the method of collision avoidance using own ship's turning characteristic about action of target ship's keeping course and velocity in various encounter.

• Solar Energy
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• v.18 no.3
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• pp.217-228
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• 1998

The purpose of this research is to investigate the characteristics of static and total pressure distribution in the upward free water jet system impinged on a downward flat plate. The rectangular nozzle was used and its contraction and aspect ratio was five and about seven respectively. Experimental conditions considered were jet velocity, distance between nozzle and flat plate, height of supplementary water. It was founded that pressure distribution on the flat plate had the Gaussian curve when the pressure at stagnation point and impinging half width were chosen as the scaling parameters. The maximum pressure was shown at the stagnation point. The central impingement velocity decreased with the increment of distance between nozzle and flat plate, and its slop of decay was similar to that of chracteristics decay region in the three-dimensional free jet.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.3
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• pp.290-295
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• 2011

On the basis of DCPA(Distance to Closest Point of Approach) and TCPA(Time to CPA), the conventional algorithms for collision avoidances have a drawback that the '72 CORLEGs(International Regulations for Preventing Collisions at Sea, 1972) has not taken into account to prevent collisions between ships. In this paper, the proposed algorithm decides whether the own ship is a give-way vessel or a stand-on vessel by observing the relative bearing of the encountered ship. To determine the ship position and time for collision avoidance, the proposed algorithm utilizes the ellipse model for ship safety domain. The computer simulation is done to represent the process of adversive behavior. Using the proposed method, the past maritime accident is analyzed. The proposed method can be effectively applied to collision avoidance by CORLEGs even when the target ship's navigational lights is invisible in poor weather and/or in the restricted visibility.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.6
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• pp.603-608
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• 2014

In the maritime traffic environment, the near-miss between vessels is the situation approaching on collision course but collision accident is not occurred. In this study, in order to calculate the near-miss between navigating vessels, the discriminating equation using ship bumper theory and vessel position clustering methods are proposed. Applying proposed module to the vessel trajectories of the WANDO waterway, we assessment navigational risk factors of vessel type, navigational speed, meeting situation.