• Journal of the Korean Society of Propulsion Engineers
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• 제20권2호
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• pp.56-66
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• 2016

Robustness is essential for model based FDI (Fault Detection and Isolation) and it is inevitable to have modeling errors and sensor signal noises during the process of FDI. This study suggests an improved method by applying NARX (Nonlinear Auto Regressive eXogenous) model and Kalman estimator in order to cope with problems caused by linear model errors and sensor signal noises in the process of fault diagnoses. Fault decision is made by the probability of the trend of gradually accumulated errors applying Fuzzy logic, which are robust to instantaneous sensor signal noises. Reliability of fault diagnosis is verified under various fault simulations.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.139-145
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• 2006

LRE(Liquid propellant Rocket Engine) is one of the important parts to control the trajectory and dynamics of rocket. The purpose of control of LRE is to control the thrust according to requiredthrust profile and control the mixture ratio of propellants fed into gas generator and combustor for constant mixture ratio. It is not easy to control thrust and mixture ratio of propellants since there are co-interferences among the components of LRE. In this study, the dynamic model of LRE was constructed and the dynamic characteristics were analyzed with control system as PID control and PID+Q-ILC(Iterative Learning Control with Quadratic Criterion) control. From the analysis, it could be observed that PID+Q-ILC control logic is more useful than standard PID control system for control of LRE.

• Proceedings of the KAIS Fall Conference
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• 한국산학기술학회 2010년도 춘계학술발표논문집 2부
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• pp.1007-1009
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• 2010

실험을 통하여 엔진의 성능을 파악하고자 한다면 적지 않은 시간동안 많은 비용과 노력이 필요하다. 최근 연구에서는 이러한 단점을 해결하기 위해 CFD를 이용 선행해석을 통해 미리 그 엔진의 성능을 예측하여 실험에 들이는 시간과 비용을 줄여가고 있다. 본 연구는 실험을 통하여 소형엔진의 성능을 알아보기 이전에 선행해석을 통해 소형엔진의 성능을 예측하고자 한다. 소형엔진의 선행 해석을 위해 전자제어 연료분사 방식의 400cc급 소형엔진을 모델링하고 1D 해석프로그램인 GT-Power를 통하여 엔진의 Toque, Power 및 배기가스를 예측하였다.

• Proceedings of the KAIS Fall Conference
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• 한국산학기술학회 2010년도 춘계학술발표논문집 2부
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• pp.1163-1165
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• 2010

가솔린 기관의 체적 효율은 흡기 장치의 효율의 척도로 표현된다. 현재 체적효율은 4행정 가솔린 엔진의 흡기장치의 특성과 공연비 제어를 위한 중요한 파라미터로 사용되고 있다. 체적 효율은 이론적으로 실린더로 흡입 가능한 양에 대한 실제로 실린더로 흡인한 공기량의 비율이다. 체적효율은 엔진회전 속도와 흡기다기관 부압에 따라 결정되는 종속변수이다. 체적 효율은 정상상태와 과도상태와 같은 엔진의 모든 운전조건을 시험하는데 한계와 제약이 매우 크다. 이 논문에서는 선형 알고리즘을 사용하여 체적 효율의 파라미터를 규명하여 선형 다항식 모델을 개발한다. 그리고 실험으로 구한 체적효율 데이터와 다항식 모델을 비교하고 객관적인 타당성을 평가 하였다.

• The Journal of Korean Institute for Practical Engineering Education
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• 제2권1호
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• pp.154-163
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• 2010

The object of this study is to investigate the penetration characteristics according to the change of stacking sequences and curvature radius in the composite laminated shell. They are staked to [02/902]S and [0/902/0]s, their interlaminar number are two and four. We are manufactured to composite laminated shells with various curvature radius. Curvature radius of composite shell is 100, 150, 200mm and ${\infty}$(it's meaning flat-plate). In general, kinetic energy after impact-kinetic energy before impact increased linearly in all specimens. Absorbed energy increased linearly as the curvature increased, and absorbed energy of [02/902]S specimen, which is small interlaminar number, was higher than [0/902/0]s specimen.

• Journal of the Korean Society of Propulsion Engineers
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• 제8권2호
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• pp.18-24
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• 2004

A fuel spiking test was performed to measure the surge margin of the compressor in a gas turbine engine. During the test, fuel spiking signal is superposed on the engine controller demand signals and the combined signals are used to control a fuel control valve. For the superposition, a subsystem composed of a fuel controller and a function generator is used. The real engine test was performed at the Altitude Engine Test Facility (AETF) in Korea Aerospace Research Institute (KARI). In the preliminary test, the fuel spiking signals are in good agreement with the dynamic pressure at the fuel line and at the compressor discharge point. After the preliminary test, a fuel spiking test to measure the surge point at a specific engine speed was performed. The test results show that the fuel spiking test is very effective in the measurement of surge.

• The Transactions of the Korea Information Processing Society
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• 제7권2호
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• pp.461-469
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• 2000

In the paper, the design and the implementation of the netscape plug-in and the speech synthesis enginegenerating the speech sounds from the text information of the web pages are described. The steps of the generating speech sound from an web pages are the speech synthesis plug-in is activated when the netscape finds the audio/xesp MIME data type embedded in the browsed web page; the HTML file referenced in the EMBED MTML tag is down loaded from the referenced URL to send to the commander object located in the said plug-in; The speech synthesis engine control tags and the text characters are extracted from the down loaded HTML document by the commander object the synthesized speech sounds are generated by the speech synthesis engine. The speech synthesis engine interprets the command streams from the commander objects to call the member functions for the processing of the speech segment data in the data banks. The commander object and the speech synthesis engine are designed as an independent object to enhancethe flexitility and the portability.

• Aerospace Engineering and Technology
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• 제7권2호
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• pp.162-169
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• 2008

Dynamic characteristics of a control valve, which plays an important role in thrust control of liquid rocket engines, have been analysed by AMESim simulator modeling. A speed control method has been proposed for the control of the valve equipped with a BLDC motor and the performances of this control method have been proved in making a comparison between the predictions of simulation and experimental results. Moreover, it is shown that a control valve with a second pre-filter is enough stable to the flow disturbances. The speed control method for BLDC motor is more simpler than PI gain scheduling method for the application in complex flow system.

• Journal of Advanced Navigation Technology
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• 제21권1호
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• pp.21-29
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• 2017

In this paper, we studied the control of the hybrid underwater glider (HUG), which has the advantage of high precision route search function and long-term mission capability. Dynamic modeling of HUG is based on numerical model of the attitude controller and buoyancy engine, thruster. We designed the control part considering the smooth control and precise sailing of HUG. A buoyancy engine capable of inhaling water is designed to control the buoyancy of HUG. And mass shifter carrying the battery was designed for controlling pitching motion of HUG. A control system for controlling the buoyancy engine and the attitude controller was constructed. In order to verify performance, we performed water tank test using manufactured HUG.

• Journal of the Korean Society of Propulsion Engineers
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• 제19권5호
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• pp.1-14
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• 2015

In case of a gas turbine engine for supersonic operation, the engine have a wide range of operating inlet mass flow rate and required high performance such as thrust and fuel consumption. Therefore, variable system and its optimal control logic are essentially needed. In this work, a method for performance prediction of a gas turbine engine with variable system compressor and its control scheme were developed. Conceptual design of compact acuation system for the operation of the variable system was also conducted. The performance of a low-bypass ratio mixed flow turbofan engine was analyzed, and it was observed that the surge margin of the engine is improved at off-design condition by applying the control scheme.