• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.374-380
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• 2015

In this paper, a dynamic model describing the 2 phase effect on the gas diffusion layer depending on load change of a fuel cell stack was developed to examine the effects of liquid water in fuel cell cathode gas diffusion layer on the fuel cell performance. For the developed model, 2 phase effect on the performance of a fuel cell stack depending on the load changes, concentration distribution of water vapor and oxygen inside a gas diffusion layer, the effect of the thickness and porosity of the gas diffusion layer on the fuel cell stack voltage were examined. As a result, a fuel cell stack voltage for the 2 phase model within the scope of the research become lower than that for the 1 phase model regardless of the load. Although oxygen molar concentration for the gas diffusion layer adjacent to the catalyst layer was the lowest, water vapor concentration is the highest. In addition, as thickness and porosity of the gas diffusion layer increased and decreased, respectively, the fuel cell stack voltage decreased.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.248-249
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• 2005

In this paper, flowfield and acoustic-field around moving bodies are simulated by the Arbitrary Lagrangian Eulerian (ALE) formulation in FDLBM. The effect of the ALE is checked by comparing flow about a square cylinder in ALE formulation and that in the fixed coordinates, and the results show good agreement. Matching procedure between the moving grid and fixed grid is also considered. The applied method in which the both grids are connected through buffer zone is shown to be superior to moving overlapped grid. Dipole-like emissions of sound wave from harmonically vibrating bodies in 2- and 3-dimensional cases are simulated.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.101-102
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• 2006

XML 기반의 Single Window은 국제 표준에 입각하여 해운 분야의 전자문서를 사용하여 국제해사기구와 전세계적으로 공통된 양식을 사용한다. 이는 동일한 양식의 전자문서를 사용하는 사용자들 간은 통용될 수 있다는 의미이며, 민원인 입장에서는 정보의 재사용성과 중복 입력의 불합리함을 줄일 수 있다. 이로써 민원인들은 입출항 수속 간소화 뿐만 아니라 해운 업무 자체에 많은 업무 개선 효과를 볼 수 있다. 본 고에서 제안한 XML 인프라스트럭처(XML infrastructure for Single Window)는 ebXML 기반의 Single Window에 적합하도록 설계 및 구현되었으며, 자원의 재사용성과 중복 투자를 방지할 수 있도록 하였다. 즉, 사용 환경에 유동적으로 적용가능 하도록 컴포넌트 방식으로 구성되었으며, 기존 시스템을 최대한 활용하도록 구성할 수 있도록 하였다.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.274-280
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• 2005

The system parameters of gas turbine engine tend to change remarkably in real operating condition. It means that operators have to consider environment and suitably control fuel flow. The conventional PID controller, however, can not guarantee good control performance in the aspect of system parameter change. This paper, therefore, proposes a scheme for integrating PID control and fuzzy technique to obtain the good performance of gas turbine engine speed control on the whole operating range. The effectiveness of the proposed fuzzy PID controller is verified through computer simulation.

• Journal of the Korean Society of Systems Engineering
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• v.17 no.1
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• pp.107-113
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• 2021

Plant Configuration Management(CM) is an activity to maintain consistency of design requirements, physical configuration, facility configuration information throughout the life cycle of the plant by systematically managing changes that occur during the plant design and operation process. Conformity between information must be ensured not only in the design stage, but also in the case of design changes in the operation and maintenance stages, and thus a computer system capable of efficiently managing them is required. In particular, in consideration of an application to small and medium-sized domestic plants, a computer system that can support configuration management at a low cost is needed. Accordingly, in this study, a configuration management system has been developed to support the management of plant design information and change procedures in the operation stage of small and medium-sized plants. Here, a case for quantitatively evaluating the effectiveness of the developed system is described.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.382-387
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• 2009

Requirement management is an important phase that has a significant influence on the project success. As a risk to a project fail is getting bigger, people adopt Systems Engineering method to the development of the effective requirement management. Accordingly, Railroad Safety Technology R&D Corps. is progressing the plan of the construction of Railway Safety Test Facilities as a part of the Railway Total Safety Project to enhance the railway safety, and carrying out researches on effective requirement management methods with Systems Engineering techniques. To support that, we introduce the Systems Engineering Requirement Management Process and propose the more effectual management method of constructing the Railway Safety Test Facilities applying the model-based systems engineering tool to the research.

• Journal of KIBIM
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• v.13 no.4
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• pp.36-44
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• 2023

Recently in Korea, efforts are underway to enhance smart construction by implementing Building Information Modeling (BIM) comprehensively across all sectors of the construction industry. This study focused on the adoption of BIM for prefab bridges currently executed in the industry and It examined the process of creating a BIM-based prefab bridge model that can support production. Additionally, it explored how prefab products made by manufacturers can be integrated with road alignments using BIM technology and how the DfMA (Design for Manufacturing and Assembly) approach, which supports production based on designed information, can be adopted. The process of creating the prefab bridge model aims to shorten production time, reduce costs, and enhance quality by leveraging digital information related to design and manufacturing within the BIM framework

• Geophysics and Geophysical Exploration
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• v.17 no.4
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• pp.231-241
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• 2014

Recently, single channel seismic survey for engineering purpose have been used widely taking advantage of simple processing. However it is very difficult to obtain high fidelity subsurface image by single channel seismic due to insufficient fold coverage. Recently, seismic waveform inversion in multi channel seismic survey is utilized for accurate subsurface imaging even in complex terrains. In this paper, we propose the seismic waveform inversion algorithm for velocity model building using a single channel seismic data. We utilize the Gauss-Newton method and assume that subsurface model is 1-Dimensional. Seismic source estimation technique is used and offset effect is also corrected by removing delay time by offset. Proposed algorithm is verified by applying modified Marmousi2 model, and applied to field data set obtained in port of Busan.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5827-5833
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• 2013

Due to science and technology evolutions, modern systems are becoming larger and more complex. In developing complex systems, Model-Based Systems Engineering (MBSE), which is approach to reduce complexity, is being introduced and applied to various system domains. However, because of the modeling being made through a variety of languages, there is a problem with communication within the stakeholders and a lack of consistency in the models. In this paper, by investigating the rule explaining the transformation of one of the only traditional diagrams, DFD, to SysML and reusing the formerly built models, we attempt to implement by SysML. Analyzing each diagram's Metamodel and validating the connection of each component through bipartite graph especially suggest an effective transformation rule. Also, by applying to naval-combat system, we confirm efficiency of this study. Establishing the results of this study as basis for conducting further study, we will be able to transform other previous models gained from formerly built system to SysML. In this way, the stakeholder's communication can be improved and we anticipate that the application of SysML will be beneficial to the much efficient MBSE.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.3
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• pp.581-587
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• 2001

Plate heat exchange(PHE) will be applied to the refrigeration and air conditioning systems as evaporators or condensers for their high efficiency and compactness. The purpose of this study is the analyze the characteristics of heat transfer and pressure drop of plate heat exchanger. Numerical work was conducted using the FLUENT code k-$\varepsilon$model. Also the dependence of heat transfer coefficient and friction factor on Reynolds number was investigated. As the Reynolds number increases, it is found that heat transfer coefficient also increases, but friction factor decreases. The study examines the internal flow, thermal distribution and the pressure distribution in the channel of plate heat exchanger. The results of CFD analysis compared with experimental data, and the difference of friction factor and Nusselt number in plate heat exchanger are 10% and 20%, respectively, Therefore the CFD analysis model is effective for the performance prediction of plate heat exchanger.