• Journal of Navigation and Port Research
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• v.27 no.2
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• pp.137-143
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• 2003

The prevention of marine accidents has been a important topic in marine society for long time, and various safety policies and countermeasures have been developed and applied to prevent those accidents. In spite of these efforts, however, significant marine accidents have taken place intermittently. Ship is being operated under a highly dynamic environments, and many factors are related with ship's collision, whose factors are interacting. So, the analysis on ship's collision causes are very important to prepare countermeasures which will ensure the safe navigation. This study analysed the ship's collision data over the past 10 years(1991-2000), which is compiled by Korea Marine Accidents Inquiry Agency. The analysis confirmed that‘ship's collision’is occurred most frequently and the cause is closely related with human factor. The main purpose of this study is to analyse human factor. For this, the structure of human factor is analysed by the questionnaire methodology. Marine experts were surveyed based on major elements that were extracted from the human factor affecting to ship's collision. FSM has been widely adopted in modeling a dynamic system which is composed of human factors. Then, the structure analysis on the causes of ship's collision using FSM are performed. This structure model could be used in understanding and verifying the procedure of real ship's collision. Furthermore it could be used as the model to prevent ship's collision and reduce marine accidents.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.2
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• pp.49-63
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• 2008

RDF is the base ontology model which is used in Semantic Web defined by W3C. OWL expands the RDF base model by providing various vocabularies for defining much more ontology relationships. Recently Jain and Farkas have suggested an RDF access control model based on RDF triple. Their research point is to introduce an authorization conflict problem by RDF inference which must be considered in RDF ontology data. Due to the problem, we cannot adopt XML access control model for RDF, although RDF is represented by XML. However, Jain and Farkas did not define the authorization propagation over the RDF upper/lower ontology concepts when an RDF authorization is specified. The reason why the authorization specification should be defined clearly is that finally, the authorizatin conflict is the problem between the authorization propagation in specifying an authorization and the authorization propagation in inferencing authorizations. In this article, first we define an RDF access authorization specification based on RDF triple in detail. Next, based on the definition, we analyze the authoriztion conflict problem by RDF inference in detail. Next, we briefly introduce a method which can quickly find an authorization conflict by using graph labeling techniques. This method is especially related with the subsumption relationship based inference. Finally, we present a comparison analysis with Jain and Farkas' study, and some experimental results showing the efficiency of the suggested conflict detection method.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.5
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• pp.592-598
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• 2008

This paper presents collision prediction and avoidance method for AGVS (Automatic Guide Vehicle System). Also, we propose the PO(Right of Path Occupying) with decentralized delay time for collision avoidance. Classified essential element of AGV's working environment is modeled in this paper. Using this model, we propose a new shortest path algorithm using A* search algorithm and obtain the information on AGVs travel time, coordinates and rotation vector. Finally, we use the AGVs information data as input for simulation program. The simulation practice is used in order to evaluate a collision prediction and avoidance, and it has been presented to demonstrate the applicability of the minimize delay time.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.11a
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• pp.214-217
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• 2022

2018 년 평창 동계올림픽부터 우리나라 사람들이 컬링이라는 종목에 큰 관심을 갖기 시작하였다. 하지만 이 종목을 직접 체험하거나 경기를 보기 위해서는 빙판이 있어야 하는 특수성과 비싼 장비, 찾아보기 힘든 경기장 등 여러 열악한 조건들 때문에 결국 올림픽 시즌에만 반짝 관심을 가졌다가 시들어버렸다. 이를 해결하기 위해서 우리는 Unity 라는 게임 엔진을 사용하여 사람들이 쉽게 접할 수 있는 컬링 게임을 제작하였다. 실제 컬링을 게임으로 만들기 위해 컬링에 필요한 도구들을 이미지로 제작하여 Unity 내부에서 저장 후 오브젝트에 입력하였고 물리 법칙을 구현하기 위해 Unity 상에서 방향, 세기, 속도, 충돌들을 프로그래밍하였으며 대한컬링연맹에 나와있는 컬링 경기 규칙서를 활용하여 게임에 적용하였다. 또한 컬링의 진행이 현실적인 운동과 비슷하게 하기 위하여 스크립트 안의 충돌 및 마찰 관련 계수를 조절하였고 이를 이용하여 반복한 결과값들을 수치화 하여 그래프로 작성해보았다. 추가적으로 컬링 게임의 점수판과 카메라 시점 등을 통해서 게임 사용자가 게임 진행에 있어서 도움이 되는 부분을 구현하였고 현실성을 위하여 Arduino 를 이용한 게임 패드를 제작하여 직접 게임하는 듯한 느낌을 들도록 하였다. 최종적으로 게임을 이용하여 컬링에 대한 이해도가 증가하고 사람들이 컬링이라는 비인기 종목에 한 걸음 더 접근할 수 있게 되고, 스포츠발전에 조금이나마 기여할 수 있게 될 것이다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.351-356
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• 2022

Among the path planning methods used to generate the ship's path, the graph search-based method is widely used because it has the advantage of its completeness, optimality. In order to apply the graph-based search method to the berthing path plan, the deviation from the path must be minimized. Path following suitability should be considered essential, since path deviation during berthing can lead to collisions with berthing facilities. However, existing studies of graph search-based berthing path planning are dangerous for application to real-world navigation environments because they produce results with a course change just before berthing. Therefore, in this paper, we develop a cost function suitable for path following, and propose a 3D A* algorithm that applies it. In addition, in order to evaluate the suitability for the actual operating environment, the results of the path generation of the algorithm are compared with the trajectory of the data collected by manned operations.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.816-824
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• 2010

The forces applying to an object in the transferring pipe of waste are analyzed and the equation of motion is established in this paper. It is shown that the equation of motion becomes the 1st order non-linear differential equation. Using its general solution, the velocity of the object in the transferring pipe of waste can be expressed in the explicit form. Noting that the velocity of object is impact velocity to the elbow or curved part of the transferring pipe of waste, the kinetic energy of the object can be calculated and the necessary impact strength of inner wall is obtained. The velocity of object is also calculated and presented in the graphic forms with the condition of air velocity 30m/sec. The impact test of cast basalt tube is carried out by the free fall of a weight and the test results show that the impact strength of the cast basalt tube is sufficient to apply to protecting inner wall of the transferring pipe of waste.

• Journal of KIISE:Databases
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• v.36 no.6
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• pp.422-433
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• 2009

As an effort to secure Semantic Web, in this paper, we introduce an RDF access authorization model based on an ontology hierarchy and an RDF triple pattern. In addition, we apply the authorization model to RDF query validation for approved access authorizations. A subscribed SPARQL or RQL query, which has RDF triple patterns, can be denied or granted according to the corresponding access authorizations which have an RDF triple pattern. In order to efficiently perform the query validation process, we first analyze some primary authorization conflict conditions under RDF subsumption inference, and then we introduce an efficient query validation algorithm using the conflict conditions and Dewey graph labeling technique. Through experiments, we also show that the proposed validation algorithm provides a reasonable validation time and when data and authorizations increase it has scalability.

• Journal of Aerospace System Engineering
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• v.18 no.2
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• pp.1-11
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• 2024

This paper applies a relative impact angle control guidance law to a communication-based multi-missile network system with uncertainties and disturbances. The multi-missile network system is represented as a transitive reduction directed acyclic graph. Furthermore, this paper introduces both centralized and decentralized guidance laws based on the graph's structure. The relationship between these guidance laws is analyzed by comparing them based on the communication structure and the presence of system noise. To analyze the effects of decentralized optimal cooperative guidance law, this paper assumes uncertainty in missile dynamics and predicted impact point information for the relative impact angle control mission. Monte Carlo simulations are conducted for various mission environments to analyze the impact of communication and its structure on the system.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10b
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• pp.661-663
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• 1998

합병 문제는 크기가 각각 l, m(l+m=n)인 두 개의 정렬된 리스트를 하나의 정렬된 리스트로 만드는 문제로 정렬 문제와 그래프 문제 등과 같은 여러 가지 문제를 해결하는데 필요한 중요한 문제이다. p($\theta${{{{ LEFT ( {λlogp} over {log(λ+1)} RIGHT ) }}}}).

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.11a
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• pp.262-266
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• 2002

본 연구에서는 가상환경 및 시뮬레이션에서 활용이 가능한 인체 모델을 개발하였다. 한국인 인체 측정 자료를 바탕으로 각 지체에 대한 기구학적 특성치와 상관관계를 얻고 인체 모델을 구성하였다. 인체 모델은 17개의 독립된 지체들로 구분되며 조인트로 연결된다. 구성된 모델은 가상환경의 신 그래프(scene graph)상에 자료화되고 DCS를 이용하여 애니메이션이 가능하도록 하였다. Madymo를 이용하여 차량 운전자의 전방 충돌 및 범퍼 통과시 지체의 거동을 해석하고 그 결과 값을 변환하여 OpenGL Performer 라이브러리를 통해 가상 공간에 가시화하였다.