• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.194-201
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• 2008

The launch vehicle upper stage generally executes collision and contamination avoidance maneuver after the satellite separation. Through this maneuver the satellite safely settles in its orbit and the launch vehicle moves away from the satellite with minimum contamination. In this paper collision and contamination avoidance maneuvers by foreign launch vehicles are analyzed. Criteria for satellite contamination during the avoidance maneuver is given for KSLV-I upperstage.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.21-22
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• 2011

In this study, an analytical algorithm for collision avoidance is proposed, which is applicable to designing collision avoidance maneuvers for two encountering ships. The minimum separation distance is defined and an appropriate maneuver sequence is computed for safe and effective collision avoidance. Two approaches: 1) collision avoidance through speed change and 2) collision avoidance through heading change, are considered, and the initiation point of the avoidance maneuver is computed analytically using the geometric configuration of the two encountering ships. To verify the feasibility of the proposed algorithm, numerical simulations are carried out using a set of ship-to-ship encountering scenarios.

• Annual Conference of KIPS
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• 2002.04a
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• pp.23-26
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• 2002

클라이언트/서버 데이타베이스 시스템 환경이 대중화됨에 따라 클라이언트 캐쉬 데이터의 일관성을 유지하기 위한 기법들이 많이 제안되고 있다. 기존의 회피-기반 기법들은 갱신의도(write intuition) 선언을 동기적(synchronous)으로 수행하는 CB(Callback) 기법과 지연(defereed)하는 O2PL(Optimistic 2-Phase Locking) 기법을 기반으로 연구가 이루어졌다. 본 논문에서는 회피-기반(avoidance-based)에서 서버에게 갱신의도 선언을 비동기적으로 수행하는 캐쉬 일관성 유지 기법을 제안한다. 본 논문에서 제안한 기법은 갱신의도 선언을 비동기적으로 수행함으로 서버의 응답을 기다리지 않고 트랜잭션 처리를 수행함으로써 좋은 성능을 보이고, 트랜잭션 철회(abort)율이 낮다는 장점을 갖는다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.12 no.1 s.24
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• pp.47-52
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• 2006

Recently, ship collision accidents account for $20%{\sim}34%$ of domestic marine accidents, also have increased continually. In this paper, therefore we propose the development of Ship Collision A voidance 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 been studied for the propose of supporting to avoid ship collision in close quarters. Besides. the program will effectively support maneuvering for collision avoidance through display of 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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.9
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• pp.1718-1726
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• 2006

In this paper, we proposed a fuzzy controller and algorithm for efficiently obstacle avoidance in unknown space. The ultrasonic sensor is used for position and distance recognition of obstacle, and fuzzy controller is used for left and right wheels angular velocity control. The fuzzification is used singleton method and the control rule is each wheel forty-nine. The fuzzy inference is used simplified Mamdani's reasoning and defuzzification is used SCOG(Simplified Center Of Gravity). The computer simulation based on mobile robot modelling was performed for the capacity of fuzzy controller and the really applicable possibility revaluation of the proposed avoidance algorithm and fuzzy controller. As a result, mobile robot was exactly reached in target and it avoided obstacle efficiently.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.7
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• pp.55-62
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• 2006

This thesis describes collision avoidance using fuzzy logic based on "Right of way" rules of ICAO and FAA and pilot's experiences for Unmanned Aerial Vehicle(UAV). To apply the rules, we designed fuzzy logic based collision avoidance system. And we also designed decision logic for enable condition of collision avoidance system. Decision logic have three kinds of core key, i.e. Relative Range, Time of CPA(Closest Point of Approach) and Distance at CPA. Application of decision logic made a possible to avoid NMAC(Near Mid-Air Collision) and it has been verified through several simulations. To conclude, we proposed the method to carry out "See and Avoid" ability on UAVs, which is capability to mingle with manned aircraft in civil airspace.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1034-1041
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• 2014

This paper propose a fuzzy inference model for obstacle avoidance for a mobile robot with an active camera, which is intelligently searching the goal location in unknown environments using command fusion, based on situational command using an vision sensor. Instead of using "physical sensor fusion" method which generates the trajectory of a robot based upon the environment model and sensory data. In this paper, "command fusion" method is used to govern the robot motions. The navigation strategy is based on the combination of fuzzy rules tuned for both goal-approach and obstacle-avoidance. We describe experimental results obtained with the proposed method that demonstrate successful navigation using real vision data.

• Journal of Energy Engineering
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• v.11 no.1
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• pp.47-58
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• 2002

This paper presents a new method for the evaluation of avoided generation costs. Unlike conventional load decrement method, it exactly considers forced outage rate and economic loading order of IPPs (Independent Power Producers). Therefore we can provide exact generation avoided costs of IPPs by the developed method. Because probabilistic simulation is conducted in this method, effects on the costs of IPPs are exactly considered. Also we suggest an allocation method of avoided generation costs by participation factor. In the case studies we have shown avoided generation costs considering loading order and forced out-age rate by using this method.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.125-127
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• 2014

본 논문은 선박의 일대다 충돌상황에서 국제해상충돌예방규칙(COLREGs, International Regulations for Preventing Collisions at Sea, 1972)을 만족하도록 피항경로를 생성하는 충돌회피 알리고즘의 개발과 적용에 관해 기술한다. 본 연구에서 제안하는 알고리즘은 조우선박의 상대 방위각, 충돌위험정도 및 상호시계와 제한시계의 시계상태에 따라 피항동작을 분류하고, 규칙기반형태의 전문가시스템인 CLIPS(C Language Integrated Production System)를 이용하여 국제해상충돌예방규칙에 따른 피항행동공간을 생성한다. 검증을 위하여 Izuma problems의 3가지 충돌상황을 가정한 컴퓨터 시뮬레이션을 수행하였으며, 다양한 충돌상황에 대하여 안전한 충돌회피경로가 생성됨을 확인 할 수 있었다.

• 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.