• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.157-162
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• 2005

Parallel implementation and performance assessment of the grid assembly in a structured chimera grid approach is studied. The grid assembly process, involving hole cutting and searching donor, is parallelized on the PC cluster. A message passing programming model based on the MPI library is implemented using the single program multiple data(SPMD) paradigm. The coarse-grained communication is optimized with the minimized memory allocation because that the parallel grid assembly can access the decomposed geometry data in other processors by only message passing in the distributed memory system such as a PC cluster. The grid assembly workload is based on the static load balancing tied to flow solver. A goal of this work is a development of parallelized grid assembly that is suited for handling multiple moving body problems with large grid size.

• 한국컴퓨터산업학회논문지
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• 제3권9호
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• pp.1189-1198
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• 2002

최근 분산시스템 환경에서 다양한 사용자의 요구에 부응하고 통신망의 효과적인 관리를 위해서는 네트워크 자원의 관리에 대한 정책기반 통신망관리시스템이 요구된다. 본 논문에서는 다양한 통신망의 효율적인 관리와 일관된 관리정책을 적용하기 위해 ECA(Event-Condition-Action) 규칙을 갖는 능동특성의 정책기반 관리객체정보를 모델링하였다. 본 논문에 기술된 정책에는 하나의 외부요인이 발생하였을 때 외부요인이 수행되기 위한 하나이상의 조건과 그 조건이 만족된 경우 수행되는 행위들로 구성된 규칙들을 기술한다. 그리고 실질적인 환경에서 적용되고 있는 ATM 관리객체 중 폭주제어 모델에 정책의 구성요소를 적용함으로써 관리객체의 동적 수행 기능이 체계적이고 정형적으로 기술되는 장점을 제시하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 심포지엄 논문집 정보 및 제어부문
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• pp.227-229
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• 2005

This paper proposes a method of implementation of digital convergence platform(DCP) which enable the service of broadcasting, communication, multimedia and home automation. Also digital convergence platform based on MPEG-21 multimedia framework can be a model to provide a distributed electronic commerce environment of multimedia and to manage of it. Platform hardware is implemented using a general purpose CPU and high performance digital signal processor and has peripheral units for network and multi I/O. It is able to run applications of multimedia which has variable formats on DSP. In addition, a personal transaction of multimedia packaged with MPEG-21 multimedia framework is provided on digital convergence platform. Like this, digital convergence platform bring up a new architecture of multimedia systems using a new generation network.

• Journal of information and communication convergence engineering
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• 제7권2호
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• pp.107-112
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• 2009

Renewable energy resources will be an increasingly important part of power generation in the new millennium. Besides assisting in the reduction of the emission of greenhouse gases, they add the much needed flexibility to the energy resource mix by decreasing the dependence on fossil fuels. Due to their modular characteristics, ease of installation and because they can be located closer to the user, PV system have great potential as distributed power source to the utilities. In this paper, a dc-de power converter scheme with the push-pull based technology is proposed to apply for solar power system which has many features such as high efficiency, stable output, and low acoustic noises, DC-DC converter is used in proposed topology has stable efficiency curve at all load range and very high efficiency characteristics. This paper presents the design of a single-phase photovoltaic inverter model and the simulation of its performance.

• 대한기계학회논문집A
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• 제30권5호
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• pp.488-495
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• 2006

The demand for the use of 3D CAD data over the Internet environment has been increased. However, transmission of 3D CAD data has delayed the communication effectiveness because of the CAD data size. Lightweight CAD file design methodology is required for rapid transmission in the distributed environment. In this paper, to derive lightweight CAD files from commercial CAD systems, a file translation system producing a native file is constructed first by using the InterOp and API of the ACIS kernel. Using the B-rep model and mesh data extracted from the native file, the lightweight CAD file with topological information is constructed as a binary file. Since the lightweight CAD file retains topological information, it is applied to the dimensional verification, digital mock-ups and visualization of CAD files. Effectiveness of the proposed lightweight CAD file is confirmed through various case studies.

• 대한전자공학회논문지
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• 제25권6호
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• pp.591-597
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• 1988

In this paper, we have studied a channel capacity affected by noise which produces burst errors in the ISDN(approx 140Kbps) data transmission using a existing PSTN. First, a digital communication system model to apply a subscriber line to a narrow band ISDN channel is presented. Second, the decision methodology of a channel capacity limitation whether the pdf of the noise generated by a waveform synthesizer is Pisson or Laplacian is described. As a result of the simulation, we have obtained that the Poission distributed noise is approached to the Guassian rather than the Laplacian under the same SNR condition.

• Journal of Communications and Networks
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• 제5권3호
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• pp.230-239
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• 2003

In this paper, we propose a framework to study how to route packets efficiently in multipath communication networks. Two traffic congestion control techniques, namely, flow assignment and packet scheduling, have been investigated. The flow assignment mechanism defines an optimal splitting of data traffic on multiple disjoint paths. The resequencing delay and the usage of the resequencing buffer can be reduced significantly by properly scheduling the sending order of all packets, say, according to their expected arrival times at the destination. To illustrate our model, and without loss of generality, Gaussian distributed end-to-end path delays are used. Our analytical results show that the techniques are very effective in reducing the average end-to-end path delay, the average packet resequencing delay, and the average resequencing buffer occupancy for various path configurations. These promising results can form a basis for designing future adaptive multipath protocols.

• 한국정밀공학회지
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• 제32권1호
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• pp.39-47
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• 2015

Globalization, unpredictable markets, increased products customization and frequent changes in products, production technologies and machining systems have become a complexity in today's manufacturing environment. One key strategy for coping with the evolution of this situation is to develop or apply an enable technology such as intelligent manufacturing. Intelligent manufacturing system (IMS) is characterized by decentralized, distributed, networked compositions of heterogeneous and autonomous systems. The model of IMS is inherited from the organization of the living systems in biology and nature so that the manufacturing system has the advanced characteristics inspired from biology such as self-adaptation, self-diagnosis, and selfhealing. To prove this concept, an innovative system with applying the advanced information and communication technology such as internet of things, cognitive agent are proposed to integrate, organize and allocate the machining resources. Innovative system is essential for modern machining system to flexibly and quickly adapt to new challenges of manufacturing environment.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2001년도 가을 학술발표논문집 Vol.28 No.2 (3)
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• pp.649-651
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• 2001

지난 수년간 인터넷의 대중화와 급속한 성장으로 분산 애플리케이션에 대한 관심이 증대되었다. 오늘날 분산 애플리케이션을 보다 쉽게 개발하기 위한 미들웨어로 CORBA와 Java RMI가 널리 사용되고 있다. 기존의 이러한 객체지향 미들웨어 정은 분산 환경은 분산 소프트웨어 컴포넌트와 분산 애플리케이션의 향상된 이식성, 상호운용성 그리고 재사용성 등을 제공하지만, 신뢰성과 고가용성의 지원은 이루어지고 있지 않다. 본 논문에서는 견고한 자바 서버 객체 그름을 지원하는 그룹통신 모델을 설계하여 분할 가능한 분산환경에서 신뢰성자 고가용성이 요구되는 분산 애플리케이션의 개발을 지원하고자 한다. 제안된 시스템은 중복된 서버 객체로 구성된 그름을 다루는 분할가능 그룹통신 서비스와 서버 객체 그름을 단일 서버 객체처럼 그룹의 메소드를 호출하는 투명한 클라이언트 호출 기법으로 구성된다.

• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.297-303
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• 2012

This paper presents the simulation results for the analysis of a lightning surge, switching transients and very fast transients within a thermal plant. The modeling of gas insulated substations (GIS) makes use of electrical equivalent circuits that are composed of lumped elements and distributed parameter lines. The system model also includes some generators, transformers, and low voltage circuits such as 24V DC rectifiers and control circuits. This paper shows the simulation results, via EMTP (Electro-Magnetic Transients Program), for three overvoltage types, such as transient overvoltages, switching transients, very fast transients and a lightning surge.