• 산업기술연구
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• 제27권A호
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• pp.61-67
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• 2007

The construction machine is the composite machine assembled by about 30,000 parts. Excavator, one kind of a construction machine, plays the leading role for export of construction equipment. It is generally impossible to produce all of the items within one company. Especially the supply of hydraulic control valves, one of the core part of the construction equipment, depends on the import heavily. So it is important to make an efficient production plan of hydraulic control valves in the company. The most important thing for the production scheduling of a hydraulic control valve is to make production schedule keeping the start date for assembly line for an excavator and to make minimization of the stock level. The production plan of hydraulic control valve includes the decision of the quantity supplied by subcontractor. This paper presents a scheme for a scheduling system of the hydraulic control valve considering the schedule of the assembly line for excavator production. This paper provides a methodology, which can make a plan of supply and production and generate a detailed schedule for daily production.

• 대한설비공학회지:설비저널
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• 제17권4호
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• pp.395-407
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• 1988

Transient flow in a cold-water supply system for cooling the inside of a coal mining pit was numerically simulated. Properly designed and presetted pressure reducing valves control the level of pressures of the piping system at normal or emergent conditions Quasi-steady relations to simulate the valve motion are obtained and the transient performance of the valve is investigated in the present paper. The present method reasonably simulate transient phenomena in the system including the pressure reducing valve. Excessive valve motion and column separation are simulated when the flow is abruptly reduced. A calculated example of the real system is also presented. The simulation can be used for the safety-check and the guidance for design and operation in emergent cases of the system.

• 한국추진공학회지
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• 제21권4호
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• pp.28-35
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• 2017

액체 추진 로켓 엔진에서 연소실로 향하는 산화제 공급은 연소기 산화제 개폐밸브에 의해서 제어된다. 산화제의 안정적인 공급을 위하여 밸브가 열려있을 때의 유량조건을 만족해야 할 뿐만 아니라, 산화제 공급라인의 예냉을 위해 밸브가 닫혀있을 때에도 요구되는 유량조건을 만족해야 한다. 본 연구에서는 연소기 산화제 개폐밸브의 재순환 유량특성을 확인하기 위한 시험을 수행하였고, 밸브 내부에 작용하는 힘평형 관계식을 이용하여 극저온 수명시험 이후 스프링 상수가 변화하는 경향을 확인하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.945-948
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• 2017

고속비행체의 연료 공급 및 냉각 시스템에 적용 가능한 고온고압 밸브를 개발하였다. 밸브 경량화를 위해 외형 사이즈를 최소화 하였고 씰(seal) 적용부를 최소화 하여 누설에 대한 강성 설계를 진행하였다. 또한 밸브 내 압력강하를 최소화하기 위해 유동해석을 통한 내부 유로를 설계하였고 최종적으로 고속비행체의 고온의 흡열연료를 모사하는 시험장비에 밸브를 설치하여 밸브 성능을 검증 하였다.

• 대한안전경영과학회지
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• 제17권4호
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• pp.161-169
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• 2015

A fire sprinkler system is very important to extinguish fire in the building. The sprinkler system initiates sprinkler discharge if the detection system identifies a developing fire and opens the pre-action valve. However, pre-action fire sprinkler systems mainly installed in the underground parking lot at the apartment complex do not properly operate at fire if the connection type of fire sprinkler systems does not properly installed and operated. This study identified the relationship between fire dispersion & damage and the connection type of water supply in the sprinkler system from many fire cases at the apartment complex in South Korea. In addition, this study also identified the water supply differences and characteristics between South Korea and foreign countries. The main purpose of this study is also to improve the water connection types in the sprinkler system that can reduce the potential failures of pre-action valve operation through electrical signal system. The study also suggests the improvement plan for water connection types in pre-action fire sprinkler system that can minimize potential failure of pre-action fire sprinkler system. The suggestions for revising the fire safe standard in South Korea includes letting the water supply pipe of sprinkler system water inlet connect to the second side of pre-action valve and the water flow device that can minimize potential failure of sprinkler system.

• 설비공학논문집
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• 제11권4호
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• pp.511-517
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• 1999

Determining the simultaneous flow rate in any particular section of piping is the important step in order to determine the size of water supply piping. Now we are using the diversity curve of common water closet in order to determine the simultaneous flow rate of water supply piping, but there is a difference between a determined flow rate of general water closet and that of water closet for water saving. This study aims to find out the fixture unit of a flush valve type water closet for water saving in office building, and to determine the correlation between the fixture units and peak flow rates on the basis of the probability theory. A flush valve type water closet for water saving that have a 7.5 second duration of flush operation with an average design flow rate 72 $\ell$/fin was considered. Simulation results indicate that the number 5 is shown to be reasonable to the fixture unit of water closet for water saving. And the design can be undersized considerably with the revised diversity curves using modified fixture unit.

• 한국유체기계학회 논문집
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• 제9권3호
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• pp.36-43
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• 2006

Recently, micro hydropower and it's useful utilization are taking a growing interest as a countermeasure of global worming by carbon dioxide and exhaustion of fossil fuel. The purpose of this study is to investigate the possibility of extracting micro hydropower wasted by a valve in water supply system using micro cross-flow hydraulic turbine. In order to fulfill the functions of controlling flow rate and pressure in substitute for the valve, air and water are supplied into an air suction hole which is installed on the side wall of micro cross-flow hydraulic turbine. The results show that in case of supplying a lot of air into the air suction hole, about 50% of flow rate and relatively high value of loss coefficient are controlled by the turbine. Moreover, including high possibility of applying the micro cross-flow turbine to water supply system, extended application of the turbine to the water discharge system of drainage and irrigation canal.

• 한국자동차공학회논문집
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• 제5권3호
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• pp.27-34
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• 1997

The effects of the intake and exhaust valve timing to improve the engine performance in a spark ignition 3-cylinder LPG engine with a closed loop fuel supply system were studied. The engine torque and power have been measured using the 75kW EC-dynamometer while adjusting the optimal fuel consumption ratio with a solen- oid driver. As the results from this experiment, when intake valve opening is $12^{\circ}$ BTDC, intake valve closing is $36^{\circ}$ ABDC, exhaust valve opening is $12^{\circ}$ ATDC, and exhaust valve closing is $36^{\circ}$ BBDC respectively, the best torque characteristics in low and high speeds for a gives engine were obtained. And also we could find that the torque characteristics in low speeds were affected by the timing of exhaust valve open. An increased valve overlap by the EVC delay was ineffectual to the torque characte- ristics improvement in high speeds.

• 한국유체기계학회 논문집
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• 제8권5호
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• pp.22-28
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• 2005

As the water supply facilities are recently getting larger, the domestic waterworks become multi-regional water supply system. Large water supply facilities generally consist of the intake pumping station, water treatment plant and water supply/distribution facilities. Although the pumping stations and the pipeline systems are used to pump up water, it often happens pipeline damage and flooding accident by the water hammer. In this paper, the intake pumping station is guaranteed by both the computer simulation and the field test analysis. This study is contributed to the safe operation program for the pumping station in which results of the adjustment on the safety plan of the pumping station, the air valve and the valve closing time.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.635-641
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• 1994

Recently, Improving the energy efficiency of a pneumatic system and reducing the consumption of compressed air were a concern of scholars at domestic and abroad. The using fields of a pneumatic system are widely used in factory automation of manufacturing line, chemical factories with explosiveness danger and petroleum industries etc. In particular, Pneumatic cylinder is applied to feeding work of workpiece, jig tools and press mechanism, reciprocation and rotary motion with rack and pinion. In this study, The experimental apparatus consisted to pneumatic cylinder, dual supply pressure regulator and solenoid valve. The dual supply pressure regulator connected to outlet port of solenoid valve. The supply pressure (4.5kgf/cm$\^$2/) of compressed air goes into the rodless chamber 1 to drive the pistion rod forward which is named working stage. The supply pressure(2kgf/cm$\^$2/) of compressed air goes into the rod chamber 2 to drive the piston rod backward which is named no-working stage. Accordingly, The research results of this study can be obtained to Energy-Saving Effects of the compressed air about 35%.