• 한국공작기계학회논문집
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• 제12권6호
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• pp.29-35
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• 2003

In this research 4 plate type ER-Valves which have same surface but different width and length are designed and an experimental apparatus is constructed. With this experimental apparatus, flow rate and pressure drop of ER fluid flowing in ER-valves are measured with varying electric field strength of ER-valve, and relation between valve types and pressure drop is also experimented. ER fluid is made silicon oil mixed with 40wt% starch having hydrous particles. If we allow the same electric field in the ER-Valve, we came to how that the pressure drop is effected by the electrode length and electrode width. When the strength of the electric field increased, the pressure drop happened big and the flow rate decreased.

• 한국공작기계학회논문집
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• 제13권1호
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• pp.63-68
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• 2004

Recently ER fluids are put to practical use in fluid power industry field. As only with electrical signal change to the valve in which ER fluid flowing, ER fluid flow is controlled, so devepment of simple ER valves have been tried. In this case a technical problem is to check the pressure drop caused from flow rate change in valves because the pressure drop is very small. In this study ER valves are designed and manufactured, and small pressure drop induced from flow rate change is checked by pressure transducer which is made with appling strain gage. The ER valves and pressure drop check method are considered to be applied to the fluid power industry.

• 설비공학논문집
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• 제21권2호
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• pp.79-86
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• 2009

The present study was investigates the effect of the parameters on the frost formation and heat transfer performance such as fin shape, air temperature and air velocity. Heat transfer rate and pressure drop by frost were experimentally investigated. Effect of the wet blub temperature and air velocity on the heat transfer performance has been also investigated. The heat transfer performance of the louver fin and tube type heat exchanger was higher by maximum of 0.85% than the corrugate fin type at the air temperature of $2.0/1.5^{\circ}C$. As the wet blub temperature of air were increased, the heat transfer rate, pressure drop and mass of frost of three test models were increased. Especially, the maximum heat transfer rate and maximum pressure drop were shown for the Type B louver fin heat exchanger. As an experimental result, the enhancement factor(EF) of louver fin and tube type heat exchanger was only $0.2{\sim}0.4$ due to the high pressure drop.

• 항공우주시스템공학회지
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• 제4권4호
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• pp.44-48
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• 2010

This paper is used the commercial magneto-rheological(MR) damper for landing gear. The damping characteristics of Commercial MR damper by changing the intensity of the magnetic field are investigated and the dynamic responses of the landing gear. it is set up tset equipment, the landing gear drop test system. The landing gear involved drop testing the gear. The landing gear is tested by implementing sky-hook control algorithm and its performance is evaluated comparing to the result.

• 한국입자에어로졸학회지
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• 제8권4호
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• pp.133-141
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• 2012

A new depth filter media was designed and samples of flat sheet as well as cartridge assembly were prepared and tested to evaluate the filtration performance and compare with the commercial product. The arrangement of the depth filter media layers is important to reach the optimal filtration parameters like filter pressure drop, particle collection efficiency and dust holding capacity. Initially, both flat sheet samples of new media and commercial product have been tested using standard test units. Tests with new depth filter media cartridges of various pleat count were conducted in order to find the optimal pleat count which would represent the lowest pressure drop. These tests give an insight on how the pleat count and the assembly configuration affect the performance of the depth filter media cartridge. By comparing the samples with a commercial product we could confirm relatively high filtration performance of the sample cartridge with pleat count 150 made of new depth filter media. The cartridge with the same pleat count exhibits better performance without the outer mesh.

• 설비공학논문집
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• 제15권2호
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• pp.132-136
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• 2003

For the study of performance evaluation on different shape heat exchangers that have the same energy consumption in a refrigerator, we make performance evaluation coefficient (PEC) which can distinguish performance of different shape heat exchangers. The results were reported in order to compare with for the dry frosting and wet frosting test as various definition of PECs. Results showed that PEC of dry frosting test is higher than that of wet frosting test because attached water droplet increases pressure drop of air-side then this decreases performance of heat exchanger.

• Nuclear Engineering and Technology
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• 제54권11호
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• pp.4146-4158
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• 2022

Ultra-high performance concrete (UHPC) has been widely utilized in military and civil protective structures to resist intensive loadings attributed to its excellent properties, e.g., high tensile/compressive strength, high dynamic toughness and impact resistance. At present, aiming to improve the defects of the traditional vertical concrete cask (VCC), i.e., the external storage facility of spent fuel, with normal strength concrete (NSC) shield, e.g., heavy weight and difficult to fabricate/transform, the feasibility of UHPC applied in the shield of VCC is numerically examined considering its high radiation and corrosion resistance. Firstly, the finite element (FE) analyses approach and material model parameters of NSC and UHPC are verified based on the 1/3 scaled VCC tip-over test and drop hammer test on UHPC members, respectively. Then, the refined FE model of prototypical VCC is established and utilized to examine its dynamic behaviors and damage distribution in accidental tip-over and end-drop events, in which the various influential factors, e.g., UHPC shield thickness, concrete ground thickness, and sealing methods of steel container are considered. In conclusion, by quantitatively evaluating the safety of VCC in terms of the shield damage and vibrations, it is found that adopting the 300 mm-thick UHPC shield instead of the conventional 650 mm-thick NSC shield can reduce about 1/3 of the total weight of VCC, i.e., about 50 t, and 37% floor space, as well as guarantee the structural integrity of VCC during the accidental drop simultaneously. Besides, based on the parametric analyses, the thickness of concrete ground in the VCC storage site is recommended as less than 500 mm, and the welded connection is recommended for the sealing method of steel containers.

• 대한기계학회논문집B
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• 제35권7호
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• pp.743-748
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• 2011

R-134a 대체 냉매인 HFO-1234yf의 성능을 가정용 냉동/냉장고에서 평가하였다. AHAM(Associ- ation of Home Appliance Manufacturers) 규격에 의거하여 HFO-1234yf를 Drop-in하여 냉매 봉입량 시험, Pulldown 시험, 냉각속도 시험 그리고 소비전력 시험을 수행하였으며, R-134a 실험 결과와 비교하였다. $43^{\circ}C$ 고온 가혹 조건에 서도 시험을 수행하였다. 결과적으로 HFO-1234yf 냉매는 Cycle 성능면에서는 R-134a와 유사하나, 냉각속도는 모세관경을 더 크게 변경시켜야 한다.

• 설비공학논문집
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• 제19권3호
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• pp.269-274
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• 2007

A 3-way valve has been applied to a distributor in a hot-water heating system and the performance of the system was evaluated in view of the variations of pressure drop and flow rate. The 3-way valve has been designed to bypass overplus hot-water when a control valve is closed. Note that the flow goes through heating pipeline in normal operation. In the present study, the measured pressure drops in each part of the flow paths show that the contribution to the total pressure drop is in the order of the supply header with control valves, piping system of each room and return header of the distributor, even though the amount of it is different according to the flow paths. As a result of performance test by sequential closing of the control valves, the variations of pressure drop and flow rate in the distributor with 3-way valves is much lower than those with previous 2-way valves, which prevent noises induced by pressure fluctuations.

• 한국항공우주학회지
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• 제42권12호
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• pp.1037-1044
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• 2014

연구에서는 달환경을 고려한 달착륙선 충격흡수장치의 시험장치 구성 및 시험을 수행하였다. 달착륙선은 착륙 시 충격 완화를 위하여 토양이 있는 지역을 착륙지점으로 선정한다. 착륙 시 발생하는 달착륙선의 가속도는 착지면의 특성의 영향을 받아 결정된다. 달착륙선의 충격흡수장치의 시험에서 달 토양을 직접 사용할 수 없기 때문에, 복제토를 사용하여 착륙시험을 수행해야 한다. 본 연구에서는 NASA의 달탐사 프로젝트를 통해 획득된 달 토양의 정보를 기반으로 달 토양과 기계적 성질이 유사한 달 복제토 KAUMLS를 개발하여 달착륙선 충격흡수장치의 낙하시험을 수행하였으며, 지면특성에 따른 충격특성 분석을 위하여 단단한 철판과 건조된 모래위에서의 낙하시험을 수행하였다.