• Proceedings of the Korean Information Science Society Conference
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• 2000.10a
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• pp.317-319
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• 2000

웹 기반 클라이언트-서버 환경을 이용한 XML 개발환경은 기존의 서버 중심적인 개발환경과는 달리 세 가지로 요약된 장점을 갖는다. 첫째는 개발자의 공간적 제약조건을 배제할 수 있다는 점과 둘째는 프로젝트의 일관성을 유지할 수 있다는 점이며, 마지막으로 웹 브라우저를 개발 및 실행환경으로 이용할 수 있다는 점이다. 따라서 본 논문에서는 웹 기반 프로그램 개발환경의 효율성과 가능성을 보여주기 위하여 웹 기반 클라이언트-서버 개념의 XML 개발도구를 설계 및 구현하고자 한다.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.1-7
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• 2007

The control design for attitude and yaw rate of 40 % scaled SMART UA Vhas been performed. Analytic selection method for a control gain is proposed to meet the design specification of desired time response considering stability margin. The sliding mode attitude controller is also proposed and compared with the simulation results of a linear controller. Additionally, a velocity and height tracking controller is devised to prepar for the flight test.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.4
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• pp.293-299
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• 2015

Various centrifugal compressors are currently used extensively in industrial fields, where the design requirements are more complicated. This makes it more difficult to determine the optimal design point of a centrifugal compressor. Traditionally, the efficiency is an important factor for optimization. In this study, the weight of the compressor was also considered. The aim of this study was to present the design tendency considering the stage efficiency and weight. In addition, this study suggested possibility of a selection of compressor design objectives at an early design stage based on the optimization results. Only a vaneless diffuser was considered in this case. The Kriging method was used with sample points from 1D design program data. The optimal points were determined in a substitute design space.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6A
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• pp.835-842
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• 2008

The response surface method (RSM) is widely adopted for the structural reliability analysis because of its numerical efficiency. However, the RSM is still time consuming for large-scale applications and sometimes shows large errors in the calculation of sensitivity of reliability index with respect to random variables. Therefore, this study proposes a new RSM in which moving least squares (MLS) approximation is applied. Least squares approximation generally used in the common RSM gives equal weight to the coefficients of the response surface function (RSF). On the other hand, The MLS approximation gives higher weight to the experimental points closer to the design point, which yields the RSF more similar to the limit state at the design point. In the procedure of the proposed method, a linear RSF is constructed initially and then a quadratic RSF is formed using the axial experimental points selected from the reduced region where the design point is likely to exist. The RSF is updated successively by adding one more experimental point to the previously sampled experimental points. In order to demonstrate the effectiveness of the proposed method, mathematical problems and ten-bar truss are considered as numerical examples. As a result, the proposed method shows better accuracy and computational efficiency than the common RSM.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.3
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• pp.25-30
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• 2014

This paper describes the design of gate driver circuits in distributed maximum power point tracking(DMPPT) controller for photovoltaic system. For the effective DMPPT control in the existence of shadowed modules, high voltage gate driver is applied to drive the DC-DC converter in each module. Some analog blocks such as 12-b ADC, PLL, and gate driver are integrated in the SoC for DMPPT. To reduce the power consumption and to avoid the high voltage damage, a short pulse generator is added in the high side level shifter. The circuit was implemented with BCDMOS 0.35um technology and can support the maximum current of 2A and the maximum voltage of 50V.

• Journal of KIISE:Information Networking
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• v.33 no.1
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• pp.1-8
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• 2006

Security protocols have usually been developed using informal design and verification techniques. However, many security protocols thought to be secure was found to be vulnerable later. Thus, the importance of formal specification and verification for analyzing the safely of protocols is increasing. With the rise of mobile communication networks, various mobile security protocols have been proposed. In this paper, we identify the security weakness of the ASK mobile Protocol using formal verification technique. In addition, we propose a new ASK protocol modifying its vulnerability and verify its robustness.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.218-221
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• 2006

High reliability and minimization of operating cost are important problems for both engine-manufacturer and user in operation of gas-turbine engine, for which various performance diagnostics including a fault identification have been a major issue nowadays. Performance estimation in the off-design conditions, however, encounters problems of large errors and of poor convergence because of much required data to be evaluated. In this study, a diagnostics code of engine performance has been developed by using GPA(Gas Path Analysis). Quantitative performance deterioration of the turbo-shaft engine for SUAV has been estimated with altitude variation and is compared with that obtained by GSP code.

• Aerospace Engineering and Technology
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• v.2 no.1
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• pp.164-170
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• 2003

KSR-III engine with film-cooled baffle was tested. The purpose of this test is to verify the effect of ablative baffle on avoiding combustion instability which occurred in the acoustic cavity case. The engine had expansion ratio of 5.04 and the test condition was design condition(oxidizer mass flow rate 42.04, and fuel 17.95 kg/s). In the test, combustion instability did not occur. So, the effect of film-cooled baffle on avoiding combustion instability was verified.

• Journal of computational fluids engineering
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• v.4 no.2
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• pp.17-30
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• 1999

The unsteady transitional boundary layer due to rotor-stator interaction was studied at two operation points, the design and one off design points. The off design point leads to lower blade loading and lower Reynolds number. A Navier-Stokes code developed in the previous study was parallelized to expedite computations. A low Reynolds number turbulence model was used to close the momentum equations. All computations show good agreement with experimental data. The wake induced transitional strip on the suction side of the stator is clearly captured at design point operation. There is no noticeable change in shape and phase angle of the wake induced strip even in the laminar sublayer. The wake induced transitional strip at off design point shows more complex structure. The wake induced transitional strip is observed only in the turbulent layer, and becomes obscure in the laminar sublayer and buffer layer. This behavior is probably consequent upon that the transition is governed by both wake induced strip and natural transition mechanism by Tollmien-Schlichting wave.

• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.125-130
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• 2003

본 논문에서는 액체로켓엔진에서 터보펌프의 160kW급 터빈을 구동하고, 액체산소와 케로신을 추진제로 사용하는 가스발생기의 설계점 연소성능시험 결과에 대해 논의하였다. 충돌형 F-O-F 인젝터, 물냉각 채널을 가진 연소실, torch ignitor, turbulence ring 그리고 측정 링을 갖는 가스발생기에 대해 기술하였고, 점화, 연소, 종료 등의 시험 cyclogram에 대해 언급하였다. 설계점에서의 연소시험 및 turbulence ring 장착여부, 연소실 길이 변화에 따른 연소시험의 결과들에 대해 기술하였다. 연소시험 결과 가스발생기는 설계점에서 안정된 작동성을 보여주었고, 연소압력 및 온도 등의 성능이 예측치에 근접하는 결과를 보여 주었다. Turbulence ring은 출구에서의 가스온도를 균일하게 분포시켜 효과적인 혼합 장치임을 보여 주었고, 4-6msec 정도에서의 잔류시간에서는 연소효율의 차이가 크지 않음을 알 수 있었다. 가스발생기 출구에서의 온도는 공급되는 추진제의 O/F ratio에 따라 매우 민감하게 반응함을 알 수 있었다.