• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅲ
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• pp.1271-1274
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• 2003

In this paper we propose a turbojet engine controller based on fuzzy inference method. Fuel flow control input is designed by fuzzy inference in order to avoid surge and flame-out during acceleration and deceleration. Acceleration and deceleration demands are used as control commands, which can achieve effective performance without surge and flame-out.

• KIEE International Transactions on Electrophysics and Applications
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• 제5C권1호
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• pp.1-7
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• 2005

This paper describes the lightning surge analysis model of extra high voltage GIS using EMTP. Various lightning current parameters were investigated in order to confirm the impact on the lightning surge analysis such as lightning current amplitude, waveform, size of GIS, tower footing resistance and surge arresters. The multi-story tower model and EMTP/TACS model were introduced for the simulation of dynamic arc characteristics. The margin between the maximum overvoltage and BIL of the GIS was about 10 percent and the margin between the maximum overvoltage and BIL of the transformer was 21 percent.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집
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• pp.170-174
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• 2005

The purpose of this study is to design the digital surge counter for lightning arresters. The used detecting method for surges is using the signal of both ends of ZnO varistor. The electronic detecting parts of the digital counter are arranged in outside of main processer for protecting it from noise. The detecting parts change detected signals into small signals. The countermeasures for noises are (1) Shielding (2) Reinforcement of power circuits (3) Cables & Circ1e core (4) Watch-doc & control of input signals.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2017년도 학술발표회
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• pp.265-269
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• 2017

Because of abrupt changes for velocity in water, transient flow is occurred in practical life. To reduce and avoid the high or low pressure of pipe network system, various surge protection facilities are used to prevent the risk in pipe network system. Especially, we focused on study not only preventing positive and negative pressure but also selecting adequate equipment for high pressurized pipelines. Several critical cases were considered by undertaking a steady state hydraulic study and transient dynamic simulation and we suggested that the surge vessel of various surge protection system was recommended to control high and low pressures on pipeline system in perspective.

• 한국항행학회논문지
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• 제15권3호
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• pp.449-455
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• 2011

본 논문에서는 연료유량이 제어 수단인 터보제트 엔진에 대해 압축기의 서지를 방지하면서 가속시간을 줄일 수 있는 제어기를 제안하였다. 퍼지이론과 PI+D 제어 알고리즘을 적용하는 터보제트 엔진 제어기를 설계하였고 Mamdani의 추론법을 적용하여 추론하고, 비퍼지화는 무게 중심법을 사용하였다. 퍼지추론 결과는 터보제트 엔진의 가감속시 서지와 flame-out 현상을 방지하기 위해 연료 유량 제어 입력으로 사용되고, 신속하고 안전하게 원하는 속도로 수렴할 수 있도록 제어기를 설계한다. MATLAB을 사용한 컴퓨터 시뮬레이션을 수행하여 제안된 제어기의 성능을 입증하였다.

• 전기학회논문지P
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• 제56권1호
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• pp.45-50
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• 2007

In this paper, this paper discusses how to improve the power control system of cold and hot water purifiers, in particular, system protecting device against abnormal voltage. The existing power supply control system came with a protecting device composed of varistor device only for impulse-type surges. Even though the existing system senses surge other than impulse-type, the system can not be protected. Accordingly, a new type of power control system was designed to protect the system from surge and ultimately prevent electricity accidents. The power control system suggested in this paper will be designed to protect the system by sensing input voltage and discontinuing power supply by means of SSR if voltage exceeding set value is sensed. To test the designed system, surge was imposed on the existing system and processes of system failure were experimented before safety of the designed power control system was simulated via P-spice program developed by Orcad in order to examine safety and reliability of the system.

• 한국항행학회논문지
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• 제18권2호
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• pp.107-113
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• 2014

본 논문에서는 무인항공기용 소형 터보제트엔진에 대해 압축기 서지현상 및 화염소실을 방지하면서 과도응답 특성을 개선하는 제어기를 설계하였다. 인공신경망과 PID 제어 알고리즘을 적용하는 터보제트엔진 제어기를 설계하고 인공신경망 역전파 알고리즘을 사용하였다. 터보제트 엔진의 가 감속 시 서지현상과 flame-out 현상을 방지하기 위해 연료 유량 제어 입력을 인공신경망 PID 제어기로 생성한다. 생성된 연료 유량 제어 입력은 신속하고 안전하게 원하는 속도로 수렴할 수 있도록 제어기를 설계한다. MATLAB을 이용한 시뮬레이션을 통해 이득 값에 따른 응답특성 비교 분석 및 신속하고 안전하게 원하는 속도로 수렴하는 제어성능을 확인하였다.

• 한국자동차공학회논문집
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• 제14권1호
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• pp.92-99
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• 2006

The swirl ratio of a charge in the cylinder was estimated by calculating the ratio of the rotary speed of charge which could be simulated from the rotary speed of paddle in the swirl measurement apparatus, to the engine speed which could be calculated by measuring intake air flow rate. The automation of the swirl ratio measurement for cylinder head was achieved by controling both valve lift in cylinder head and a suction pressure of surge tank using two step-motors. The number of measurement position for calculating mean swirl ratio was varied by adjusting the interval of valve lift. The mean swirl ratio with varying the number of measurement position showed nearly constant value. Two measurement methods for measuring the swirl ratio were compared, one was to control the suction pressure of the surge tank with PID (proportional, integral, differential) mode with by-pass valve controlled by the step motor and the other did not control the surge tank pressure by fixing the by-pass valve. The difference of the mean swirl ratio between the two measurement methods showed nearly constant value with varying the number of measurement position. This means that the w/o PID control method could be preferred to the PID control method which has been used, due to the simpleness of the swirl measurement.

• 대한기계학회논문집B
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• 제40권5호
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• pp.297-304
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• 2016

통상 제어기 설계용으로 개발되는 차량용 수퍼 차져의 동적 거동 모델은 경험식에 의존한 압축기 맵을 활용하고 있어, 실제 서지 현상의 발생에 따른 시스템의 영향과 거동특성을 모사하는데 한계가 있다. 본 연구에서는 수퍼 차져의 운전 동특성을 모사할 수 있는 해석기반 압축기 모델을 개발하고 운전 변동성에 따른 압축기의 운전 추이를 모사하고자 한다. 모델 개발은 SIMULINK$^{(R)}$ 환경에서 진행하고, 기준 동특성 모델은 Greitzer의 압축기 모델을 적용하였다. 해석 결과는 실험 결과와 비교 검증을 통해 모델의 타당성을 확인하였으며 운전 특성 변화에 따른 압축기 성능 및 서지 발생 가능성에 대해 확인 하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권6호
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• pp.253-259
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• 2002

This paper deals with the effects of grounding conductors for metal oxide surge arresters. When surge arresters are improperly installed, the results can cause costly damage of electrical equipments. In particular, the route of surge arrester connection is very important because bends and links of leads increase the impedances to lightning surges and tend to nullify the effectiveness of a grounding conductor. Therefore, there is a need to know how effective installation of lightning surge arresters is made in order to control voltage and to absorb energy at high lightning currents. The effectiveness of a grounding conductor and 18 [㎸] metal oxide distribution line arresters was experimentally investigated under the lightning and oscillatory impulse voltages. Thus, the results are as follows; (1) The induced voltage of a grounding conductor is drastically not affected by length of a connecting line, but it is very sensitive to types of grounding conductor. (2) The coaxial cable having a low characteristic impedance is suitable as a grounding conductor. (3) It is also clear from these results that bonding the metal raceway enclosing the grounding conductor to the grounding electrode is very effective because of skin effect. (4) The induced voltages of grounding conductors for the oscillatory impulse voltages are approximately twice as large as those for the lightning impulse voltages.