• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제10권1호
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• pp.25-36
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• 2004

본 논문은 전기단층촬영의 실시간 영상 복원을 위한 마스터-슬레이브 구조를 갖는 분산 전기 단층촬영 알고리즘을 제안하고 그 성능을 평가한다. 영상복원은 그 수행시간이 미지수의 수에 3제곱에 비례하는 계산 위주의 응용으로서 영상의 정밀도를 위해 미지수를 증가시키면 그 수행시간이 급격히 증가한다. 마스터는 순차적인 루프에 진입하기 전에 각 컴퓨팅 노드에 독립적인 프레임 데이터를 분배하여 병렬로 기저노드를 추출하도록 하고 그 결과를 취합하여 그룹화함으로써 미지수의 수를 감소시킨다. 지역망으로 연결된 컴퓨팅 노드들은 MATLAB이 설치되어 기본적인 계산능력을 갖고 있으며 MATLAB 자료구조를 효율적으로 교환할 수 있는 명령이 동적 링크 라이브러리로 구현되어 있다. 또한 마스터에는 병렬 행렬 연산, 고속 자코비언 둥이 구현되어 순차적인 부분의 계산을 효율적으로 수행한다. 구현된 각 요소들의 성능을 측정한 결과 병렬 라이브러리는 전체 복원 시간을 50% 가까이 감소시킬 수 있으며 분산 알고리즘은 4개의 노드가 협력작업을 하는 경우 주어진 대상 물체에 대해 12배 빠른 속도로 영상을 복원할 수 있다.

• 대한조선학회논문집
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• 제47권4호
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• pp.628-645
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• 2010

To perform the engagement level simulation between the underwater vehicle model and the surface model those are constituted with various systems/ sub-systems, we implemented four different federates as a federation according to the IEEE 1516 HLA (High Level Architecture) protocol that is the international standard in the distributed simulation. Those are CFCS (Command and Fire Control System) federate, motion federate, external entities (torpedos, countermeasure and surfaceship) federate, and visualization federate that interacts with OSG (Open Scene Graph)-based visualization rendering module. In this paper, we present the detailed method about the model constitution for discrete event simulation in the distributed environment. For the sake of this purpose, we introduce the DEVS (Discrete Event System Specification)-HLA-based modeling method of the CFCS federate that reflects not only the interations between models, but also commands from user and tactics manager that is separated from the model. The CFCS federate makes decisions in various missions such as the normal diving, the barrier misision, the target motion analysis, the torpedo launch, and the torpedo evasion. In the perspective of DEVS modeling, the CFCS federate is the coupled model that has the tactical data process model, command model and fire control model as an atomic model. The message passing and time synchronization with other three federates are settled by the $m\ddot{a}k$ RTI (Runtime Infrastructure) that supports IEEE 1516. In this paper, we provides the detailed modeling method of the complicated model that has hierarchical relationship such as the CFCS system in the submarine and that satisfies both of DEVS modeling method for the discrete event simulation and HLA modeling method for the distributed simulation.

• 한국CDE학회논문집
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• 제17권5호
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• pp.353-363
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• 2012

As the distributed simulation system has been developed in the defense modeling and simulation, interoperability among heterogeneous simulators is essential to achieve the objectives of the distributed simulation system. However, the interoperability has been a problem to synchronize synthetic environment among many heterogeneous simulators that utilize different environmental data formats. SEDRIS (Synthetic Environmental Data Representation and Interchange Specification) was initiated to solve the problem of the interoperability. SEDRIS provides a standard mechanism to promote data interchange and reusability, and it represents all environmental things from ocean, land and atmosphere to the universe. Although SEDRIS provides various advantages as a standard environmental data format, applying of SEDRIS has been hindered by its broadness and complexity. The main objective of this paper is to explain application development process to improve SEDRIS usability for the atmosphere and ocean. The developed application of this paper provides auto-generation of SEDRIS data with minimum user's input, and the auto-generated SEDRIS data is also visualized and verified by the application.

• 정보처리학회논문지A
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• 제18A권3호
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• pp.81-92
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• 2011

제품수명주기(Product life cycle) 중 설계단계에서 생성되는 3차원 CAD 데이터를 다양한 단계에서 활용하고자하는 노력이 관련 산업 분야에서 이루어져 왔다. 그러나 3차원 CAD 데이터는 데이터 처리를 위한 많은 컴퓨팅 자원을 요구하고 설계지식이 유출될 수 있는 위험이 있으며, 라이선스 비용이 따르기 때문에 원격지 협업 검토나 마케팅, 전자 기술 매뉴얼과 같은 서비스단계에서 활용하기에 적합하지 않다. 이러한 문제점들을 해결하기 위해 경량화된 가시화 파일형식과 이를 적용한 응용시스템에 대한 다양한 연구가 수행되었으나, 제안된 경량화 파일형식들은 대부분 기업 혹은 기관의 독자적인 형식으로 서로 간에 공유될 수 없으며, 제품의 형상 정보와 함께 제품구조 정보를 표현하는데 한계점을 보이고 있다. 본 연구에서는 이를 해결하기 위하여 웹 기반 3차원 그래픽 표준인 X3D를 활용하여 제품의 형상 정보뿐만 아니라 구조 정보의 표현이 가능한 X3D 기반 데이터 집합인 prod-X3D(Enhanced X3D Dataset for Web-based Visualization of 3D CAD Product Model)를 정의하고, 3차원 CAD 데이터로부터의 변환 기법을 제안한다.

• KIEAE Journal
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• 제13권4호
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• pp.33-41
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• 2013

The impervious area on the surface of urban area has been increased as buildings and artificial land cover have continually been increased. Urban development has gradually decreased the green zone in downtown and alienated the city from the natural environment on outskirt area devastating the natural ecosystem. There arise the environmental problems to urban area including urban heat island phenomenon, urban flood, air pollution and urban desertification. As one of urban plans to solve such problems, green roof system is attracting attentions. The purpose of this study was to investigate flood discharge and heat reduction effect according to the green roof system and to quantify effect by analyzing through simulation water and heat cycle before and after green roof system. For the analysis, Distributed hydrologic model, WEP (Water and Energy transfer Processes) and WEP+ model were used. WEP was developed by Dr. Jia, the Public Works Research Institute in Japan (Jia et al., 2005), which can simulate water and heat cycle of an urban area with complex land uses including calculation of spatial and temporal distributions of water and heat cycle components. The WEP+ is a visualization and analysis system for the WEP model developed by Korea Institute of Construction Technology (KICT).

• 한국컴퓨터그래픽스학회논문지
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• 제1권2호
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• pp.213-225
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• 1995

3 차원 볼륨 데이터를 시각화(visualization)하기 위해서는 많은 계산 량과 메모리 량을 필요로 한다. 단일컴퓨터에서 순차 알고리즘을 이용하여 데이터를 시각화하고 분석하는 것은 실시간 응용 프로그램에는 부적합하다. 기존의 병렬 볼륨 렌더링에서의 데이터 분할 방법은 대부분 정적 로드 밸런싱(static load balancing)에 기반하고 있다. 동적 로드 밸런싱에 기반한 기존의 방법들은 불륨 데이터의 정규성(regularity)을 이용할 수 없다는 단점이 있다. 본 연구에서는 3 차원 볼륨 데이터에 대하여 로컬 태스크 큐(local task queue) 기법에 기반한 새로운 로드밸런싱 알고리즘을 제안한다. 제안한 방법은 계산에 참여할 노드(node)들을 PVM(parallel virtual machine)의 동적 프로세스 그룹(dynamic process group: DPG)을 이용하여 정적으로 그룹화(grouping)한다. 각각의 DPG들은 로컬 태스크 큐를 기반으로 단위 서브-블록에 대하여 동적 로드 밸런싱을 수행한다. 최적화된 레이 캐스팅 알고리즘들을 분산 환경에 새롭게 적용함으로써 로드 밸런싱으로 생길 수 있는 오버 헤드를 최소화하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 특별세미나 특별세션
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• pp.161-169
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• 2006

To develop a Maglev successfully, it is necessary to develop the core technologies such as levitation and propulsion system and construct engineering system which can integrally evaluate performances of Maglev and provide technical reviews parametrically In this paper, we designed the Maglev running performance simulator which can provide decision-making Information for direction of development of Maglev and examination for running performance about the change of various design parameters such as safety and stability, noise, and ride quality. The designed system is an engineering-based system and can be developed using engineering framework by KIMM which can integrate diverse CAE systems in distributed environments and provide systematic information management. And it also provides VR-based visualization and web-based user interface except VR system which requires special hardware system.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.553-556
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• 2003

The objective of this study is to implement geological functions on the Internet such as the visualization, search and analysis of geological data. To improve their performance and reduce the cost during development, special concerns should be given to the dynamic integration and interoperability of them. XML Web Service technologies can be adopted and OpenGIS specifications should be considered for the integration of distributed GIS components and their interoperability. Because standard Internet protocols and XML Messages are used in the Web Service, it makes the integration among different hardware and software systems possible. OpenGIS specifications also enable users to get benefits from geographic information and services across any network, platform and application. A prototype of efficient Internet GIS applications has been suggested in this study.

• 한국해양공학회지
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• 제10권4호
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• pp.128-140
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• 1996

To analyze a formation process of the soots in spray flame in the combustion chamber, an optically accessible DI Diesel engine was used for visualization. The images of the flames and soots were visualiaed with high speed camera by Schlieren method and Light extinction method. The spray flame and soot images on the films were analyzed at the various engine operating conditions. Soot distributed widely in spray flame and its concentration was about $100g/m^3$ at the position close by nozzle tip of spray flame region, however it decreased below $20g/m^3$ at the corner of combustion chamber due to soot oxidation.

• 한국정밀공학회지
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• 제20권2호
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• pp.120-128
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• 2003

When considering the use of rapid prototyping (RP), there are many issues a designer has to address for handling an STL model, the de facto standard fur RP. Today designers can skip all these issues by visiting web-based service bureaus that readily supply needed information for the RP services. Since orders are taken for RP parts through the web page of service providers designers are now asked to upload their STL files to the company server either by direct upload, ftp file transfer, or as an e-mail attachment. If the service bureau, however, fixes or edits an STL filceto optimize the RP process but neglects to tell its customer about the rework in detail, it may cause problems down the line in processing of the original CAD data for other applications. In this paper, we propose a framework for a collaborative virtual environment between CAD designers and RP processes on the internet which directly provides designers with an advanced preprocessor functionality, design visualization, as well as model display, repair, and slicing over the network. This can help smooth data transfer from CAD to RP process with minimum inconsistency in CAD.