• Journal of the Korean Society of Propulsion Engineers
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• v.7 no.3
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• pp.22-29
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• 2003

The propulsion feeding system of KSR-III is composed of tubes, valves and PSC, and controls the flow of propellant entering to engine. The test of PTA-I is carried out to verify the characteristic of propulsion feeding system and component. The tests of operation characteristic of component, hydraulic characteristic of tubes, flow control using venturi, oscillation of dynamic pressure, characteristic of regulator are carried out. Troubles of component are found out, and renewed, and the performance of the propulsion feeding system is verified through PTA-I. The results of PTA-I are used to the configuration of propulsion feeding system and test of PTA-II.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.454-459
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• 2017

In this study, a thermal system was designed using a 3-way valve and PTC attached to a solar module. This design could help solve the problem of rising fossil fuel costs caused by limited reserves and environmental problems resulting from fossil fuel use. The thermal system is a hot-air and heating control system composed of a temperature sensor part, mode setting part (for hot air and heating modes), supply part, and thermal system control part. The temperature sensor part has piping and an indoor temperature display, and the temperature setting part has multiple monitoring functions. The mode setting part switches between hot air and heating modes and can be used to set the temperature. The thermal system control part performs functions such as PTC control and temperature setting, PTC day and night and time selection, hot air and heating control, and three-way valve selection. The results verify that the system operates with stable response speeds of $680{\mu}s$ in the temperature sensor part, $700{\mu}s$ in the mode setting part, and $610{\mu}s$ in the thermal system control part.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.184-192
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• 2022

Valve internal leakage is caused by damage to the internal parts of the valve, resulting in accidents and shutdowns of the piping system. This study investigated the possibility of a real-time leak detection method using the acoustic emission (AE) signal generated from the piping system during the internal leakage of a butterfly valve. Datasets of raw time-domain AE signals were collected and postprocessed for each operation mode of the valve in a systematic manner to develop a data-driven model for the detection and classification of internal leakage, by applying machine learning algorithms. The aim of this study was to determine whether it is possible to treat leak detection as a classification problem by applying two classification algorithms: support vector machine (SVM) and convolutional neural network (CNN). The results showed different performances for the algorithms and datasets used. The SVM-based binary classification models, based on feature extraction of data, achieved an overall accuracy of 83% to 90%, while in the case of a multiple classification model, the accuracy was reduced to 66%. By contrast, the CNN-based classification model achieved an accuracy of 99.85%, which is superior to those of any other models based on the SVM algorithm. The results revealed that the SVM classification model requires effective feature extraction of the AE signals to improve the accuracy of multi-class classification. Moreover, the CNN-based classification can be a promising approach to detect both leakage and valve opening as long as the performance of the processor does not degrade.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.203-205
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• 2006

대용량 인버터의 기본 구성요소인 밸브를 시험하는 방식에 대해 제안하였다. 대용량 인버터를 구성하기 위해서는 전력용 반도체 소자를 직렬로 연결하여 고전압을 스위칭할 수 있는 밸브가 필요하다. 이 밸브의 Snubber 회로의 적정성, 정격전압, 정격전류에서 정상적으로 스위칭이 이루어지는지 등의 검증이 필요하다. 본 본문에서는 전력용 반도체 소자에 이러한 시험조건을 제공하는 시험방식을 제안하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.2853-2857
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• 2012

In this paper, 3-dimensional designing program, Solidwork was used in designing in order to investigate structure and characteristics of a pressure reducing valve which was used as an apparatus for keeping regulated pressure of water supply equipment system and also 2-dimensional drawing was made to manufacture a pressure reducing valve in the field.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.820-825
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• 1996

This paper is concerned with effective operating method of pneumatic on-off valves for improving position control accuracy, valve life-time and position settling time using modified pulse width modulation with dead-zone. The pneumatic system using on-off valves studied in this paper has advantage of simple construction and low cost compared with a system with servo-valves. The performance of proposed control system is investigated experimentally for the position control of a pneumatic cylinder using on-off valves. Experimental results show that the proposed algorithm for valve operation can be used to obtain fast and accurate position control and to prevent on-off valves from unnecessary switching.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.572-573
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• 2012

전력 수요 급증과 전력 기술 발전으로 인해, 오늘날 HVDC 기술이 널리 사용되고 있다. 또한 지구 온난화, 녹색 에너지 개발, 스마트 그리드 사업 등으로 인해 세계적으로 HVDC 수요가 급증하고 있는 추세이다. 국내에서도 제주-해남간 HVDC 1호기가 이미 운영 중에 있으며, 제주-진도간 HVDC 2호기가 2012년 완공을 목표로 현재 설치 중에 있다. 2009년 HVDC 사업에 진출한 LS산전은 지난해 변환용 변압기를 국내 최초로 생산한데 이어, HVDC 핵심 요소인 싸이리스터 밸브(thyristor valve)도 개발 완료 하였다. 싸이리스터 밸브는 HVDC 시스템의 변환설비 중 심장 역할을 하는 핵심적인 설비로 교류를 직류로, 또는 직류를 교류로 변환시켜 교류 계통에 전력을 공급하는 장치로, 사용하기 전에 성능을 충분히 검증해야 한다. LS산전은 독자적으로 개발한 싸이리스터 밸브를 IEC 규격에 따라 엄격히 시험하여 성능을 입증하였다. 본 논문에서는 개발 시험의 일부로 수행한 싸이리스터 밸브에 대한 절연 시험(dielectric test)를 소개하고자 한다.

• Journal of the Korean Vacuum Society
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• v.15 no.6
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• pp.594-604
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• 2006

Gas fueling systems operated in the mode of a fixed valve opening at a constant line pressure, and the mode of a constant inlet flow are simulated to establish the relationships between the gas flow pattern and the tube dimensions under various system conditions.

• ICROS
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• v.12 no.2
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• pp.34-38
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• 2006

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.1825-1830
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• 2014

Environmental emission of recent automobile is drastically enhanced that it is one of the obvious assignments of exhaust system. This study is a purpose to establish of influence distribution on maxima and minima through the location of pressure on exhaust variable valve. The experiment are checked with real angles using camera which exhaust variable valve is opened side of point. Data has extracted to opening angles with internal flow, pressure. Exhaust variable valve through the floating analysis was analyzed the characteristic of location point about pressure and velocity. The pressures indicated the reduced results internal pressure within muffler. The velocity indicated an opposite results and vibration state of valve was verified to be operated as high speed from lower section. The conclusion to obtain from this study was found out the result to make the optimum back pressure condition as more increasing pressure distribution on valve face if the velocity location attracted by bottom point in order to improve for engine performance.