• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.1-10
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• 2006

An optimization study on a small turbopump impeller operating at the low specific speed is conducted to obtain high output head at the impeller exit. Its specific speed in SI unit (RPM, m3/sec, m) is 4.0, and the outer diameter is 56mm. On the optimization, the outer diameter of the impeller is maintained constant to restrict the pump size, and an objective function of pressure head is maximized with eight design variables, which are related with designing an impeller shape. The response surface method is used to the optimization scheme, and the commercial code CFX-10 is applied for numerical analysis. The pressure head of the objective function obtained with an optimized impeller is increased by 9.7% compared with that obtained on an impeller designed with typically recommended design parameters. This increment is caused by reducing the recirculation region within the impeller passage.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1993.10a
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• pp.99-105
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• 1993

본 연구에서는 세탁통 및 감속장치가 스너버(Snubber)와 지지 스프링에 의 해서 지지되는 하부지지형 세탁기를 모델로 선택하였으며, 시스템의 동특성 해석을 위하여 세탁기를 회전체를 갖는 강체 현가 시스템으로 모델링하고 운동방정식을 구하여 수치 해법을 적용하여 진동 특성을 계산하였다. 세탁기 의 진동 형태를 예측하기 위해서 밑판의 마찰 계수, 스터버의 곡률 반경, 지지 스프링 계수 및 위치 등을 진동량에 영향을 미치는 설계 변수로 선정하여 결과를 구하였으며, 이 자료들을 설계 변경시에 이용할 수 있게 하였다.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.4
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• pp.241-248
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• 2010

This paper deals with the performance analysis and design of the Darrieus-type vertical axis turbine to evaluate the effect of key design parameters such as number of blade, blade chord, pitch and camber. The commercial CFD software FLUENT was employed as an unsteady Reynolds-Averaged Navier-Stokes (RANS) solver with k-e turbulent model. Grid system was modelled by GAMBIT. Basic numerical methodology of the present study is appeared in Jung et al. (2009). Two-dimensional analysis was mostly adopted to avoid the barrier of massive calculation required for parametric study. It was found that the highly efficient turbine model could be designed through the optimization of design parametrrs.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.3
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• pp.107-114
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• 1999

Design Axiom proposed by N. P. Such consists of Independence Axiom & Information Axiom. Based on the Independence Axiom, it is very useful specially for early design stage such as conceptual design to generate the design alternatives by considering both functions and structures of product. Since the Information Axiom shows that the design solution should have a least information to be the best one among the many alternatives, this axiom can be used for the best selection purpose during the preliminary design stage. In this paper, the possibility of Design Axiom in marine design application is checked by carrying out three examples of marine design. In the conceptual design of thruster, it is proven to use the Independence Axiom very effective by relating directly functional requirements with design parameters, one by one. In main engine selection example, Information Axiom is used to select best solution among alternatives by choosing the one having the minimum information quantity. For similarity based design in which the selection of changing design variables and the amount of those are important, it is proved that design axiom applied to Barge design case would be very effective and useful. As functional requirements and constrains were not clarified in early design stage, design axiom shows some difficulty for larger system design like ship which is basically carried out by an incremental and iterative process.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.51-56
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• 2010

There are two main software in COMS ground station at the normal mode operation - stationkeeping and wheel off-loading. In this paper, ground software validation test for wheel off-loading is summarized and described. The wheel off-loading was performed the design change from E3000 heritage and analyzed. The wheel off-loading of ground software has two part; one is wheel off-loading management for parameters change at the thruster set switching time and the other is wheel off-loading set-point being sent to satellite for the reference momentum.

• Journal of Korea Game Society
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• v.11 no.2
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• pp.39-44
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• 2011

Computer games need game formulas which express game rules by mathematical functions because the game rules are automatically processed by computers. The game formulas are usually multi-variable functions. So the design of a game formula is a complex and difficult problem because it is the same problem of the design of a multi-variable function which should satisfy the related game rules. In this paper we propose a new method which can systematically design game formulas. The purposed method is the decomposing of tree structure for a game formula by analyzing the tree structure of the operands which have single-variable functions on the lowest levels. So the design method can change the complex and difficult problem of the design of a multi-variable function to the simple and easy problem of the design of the single-variable function which should satisfy the related game rules.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.5
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• pp.267-274
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• 2018

For successful BIM settlement, it is a key technic for engineer to design structures in the 3-dimensional digital space and to work out related design documents directly. Lately many BIM tool has been released and each supports their 3-dimensional object libraries. But it is not easy to apply those libraries to design transportation infra structures that were placed along the route(3-dimensional line). Moreover, in case of design changes, it is so difficult to reflect those changes with the integrated model that was assembled by them. Because of they were developed without consideration for redundancy of parameters between objects that were placed nearby or were related each other. In this paper, a method to develop module for modeling and placing 3-dimensional object for transportation infra structures is presented. The modules are employed by a parametric method and can deal with design changes. Also, for a railroad bridge, through developing user interface of the integrated 3-dimensional model that was assembled by those modules the applicability of them was reviewed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.8
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• pp.683-691
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• 2014

Significance of SAR(Synthetic Aperture Radar) satellite regadless of weather have grown for Earth observation. According to the cost-effective trend in satellite development, SAR antenna is actively studied. It's a competitive candidate to use deployable SAR antenna out of CFRP. In this study, variables for an antenna configuration model was researched and evaluated. The design of the antenna was structurally analyzed by FEM(Finite Element Model). Tool-kit was developed for modifying the SAR antenna model easily in accordance with system requirement change. In the tool-kit, antenna configuration design and error analysis of the antenna surface could be achieved. And compatibility of tool-kit results to CST, a RF analysis program, was confirmed.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1581_1582
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• 2009

본 논문에서는 T형 분기 도파관 내 Septum의 최적설계를 위하여 상용 전자파해석 소프트웨어의 API(Application Program Interface) 기능을 활용하는 VBA(Visual Basic Application) 기반 설계 인터페이스를 개발 하였다. 최적설계의 설계 변수는 도파관 내에서 Septum의 위치와 크기로 하였고, 목적 함수는 도파관의 반사계수($S_{11}$)를 가장 작게 하면서 T형 분기 도파관에서 출력되는 에너지를 2:1로 분배하도록 설정하였다. 목적함수는 본 논문에서 정한 함수이며 설계 목표에 따라 인터페이스 내에서 변경이 가능하다. 설계 인터페이스는 마이크로소프트사의 엑셀을 이용하였고 인터페이스 내에서는 사용자가 원하는 T형 분기 도파관의 크기 설계가 가능하며, 입력 port의 입력 모드를 설정하고, 해석 주파수를 선택하여 사용자가 정한 목적 함수에 맞는 최적화된 Septum의 크기와 도파관 내에서의 위치를 찾을 수 있게 하였다. 또한 사용자가 원하는 위치에서의 E Field, H Field, 전류 밀도를 크기 또는 복소수 형태의 수치 데이터로 획득할 수 있도록 설계하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.526-531
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• 1996

영광5,6호기 유출관계통은 영광3,4호기의 유출관계통과는 달리 세개의 유출수 압력강하 오리피스 및 유출관 오리피스 개폐밸브론 이용하여 유출유량 및 압력을 제어한다. 새로이 설계 변경된 유출관계통의 성능 및 운전을 평가하기 위해서 Modular Modeling System(MME) 코드를 이용하여 분석을 수행하였다. 분석결과 배압제어기 제어변수의 계수선정이 계통의 과도현상에 매우 큰 영향을 미치고 있기 때문에 배압제어기 제어변수 선정이 계통의 과도현상 완화에 매우 중요한 인자임을 알 수 있었다. 그리고 배압제어기의 계수만 적절하게 선정되어 있다면, 유출관오리피스 개폐밸브의 Stroke 속도변화에 따른 계통의 과도현상에 미치는 영향은 거의 없음을 알 수 있었다. 또한 유출관오리피스 개폐밸브 특성이 선형인 경우가 Equal Percentage 특성을 갖는 경우 보다 과도현상 방지측면에서 우수하며, 배압제어기 제어변수의 계수만 적절하게 잘 선정된다면 유출관오리피스 개폐밸브의 운전에는 관계없이 계통의 과도상태를 적절하게 제어할 수 있다는 것을 알 수 있었다.