• Journal of Chest Surgery
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• v.43 no.6
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• pp.602-613
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• 2010

Background: As life expectancy has been increased, the cardiac valve disease has been increased. In past, mechanical valve for valve replacement surgery was used widely, but it has many weaknesses, such as hemorrhage, teratogenic effect caused by warfarin, acute mechanical failure, taking warfarin during life, etc. So, the tissue valve is used widely and researches for durability of tissue valve are in progress. Tissue valves being used are all imported in Korea, and there is a lack of information on its geometry and design. So, we studied the geometry of porcine aortic and pulmonary valve, and tried to suggest theoretical basis for making the aortic and pulmonary valve. Material and Method: We harvested aortic and pulmonary valves of 25 pigs and measured the geometry of valve at fresh and glutaraldehyde (GA) fixed state. In each group, we measured the diameter of the base, diameter of commissure, valve height, commissural height, etc. Also, for making implantable porcine and bovine pericardial valve, we designed the valve stent form, thickness, height, and leaflet size, form, thickness by different size of valve. Result: The aortic and pulmonary valve geometry and ratio were measured in each group. The right coronary cusp of aortic valve and right facing cusp of pulmonary valve was bigger than other cusps and non coronary cusp was smaller than others (RCC: NCC : LCC=1 : 0.88 : 1). Valve height was correlated to the leaflet size. We designed the outer diameter of stented porcine aortic valve from 19 mm to 33 mm and designed stent height and width, using previous measured ratio of each structure, stent thickness, working thickness (for making valve). Also, we designed the size of stent and form for stented bovine pericardial valve, considering diameter of valve, leaflet length, height and leaflet minimum coaptation area. Conclusion: By measuring of 25 pig's aortic and pulmonary valve geometry and ratio, we can make theoretical basis for making implantable stented porcine valve and bovine pericardial valve in various size. After making implantable valve using these data, it is necessary to do in vivo and in vitro researches, furthermore.

• Journal of Chest Surgery
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• v.20 no.1
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• pp.60-64
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• 1987

We compared between prosthetic aortic valve size and aortic annulus size in supravalvular aortic cineangiogram in 30` RAO view postoperatively. Retrospectively, supraaortic cineangiogram of 27 patients among the patients underwent aortic valve replacement only or double valve replacement from April, 1986 to January, 1987 was examined and measured the aortic annulus size. In comparing the two values, the cases within 1mm is 22, and the cases within 2mm is 25, correlation coefficient yield r = 0.92. In two cases, the difference between two values is within 3mm We concluded that to prevent the complication from mismatching the prosthetic aortic valve size to patient`s annulus size [e.g. left ventricular failure, hemolysis, limited exercise tolerance], prediction of the prosthetic valve size preoperatively by use of cineangiogram is useful.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.605-608
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• 2008

In this paper, a numerical investigation of three-dimensional, two-phase flow field around a butterfly valve is conducted. The butterfly valves that have different opening angles, $10^{\circ}{\sim}90^{\circ}$, and two profiles of the shaft boss are compared with various cavitation numbers and Reynolds numbers. This paper focused on the flow analysis in the original butterfly valve and new design butterfly valve in order to decrease cavitation and loss. It is found that the butterfly valve with a cone-type shaft boss greatly reduces the cavitation and loss, compared to the original shaft boss by 20${\sim}$30%.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.64-65
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• 2002

Recently the synthetic antiferromagnetic layer (SAF) has received much attention because it replaces the pinned layer of the conventional spin valve (CSV) sensors and its overall performance [1], The spin valve (SV) with SAF has the from buffer/F/Cu/APl/Ru/AP2/AF, where F is the soft ferromagnetic layer (typically NiFe with CoFe interfacial doping), AP1 and AP2 are two ferromagnetic layers (typically CoFe alloys) antiferromagnetically coupled through a thin Ru layer. (omitted)

• Journal of Magnetics
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• v.5 no.2
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• pp.50-54
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• 2000

NiMn-pinned spin valve films consisting of a layered glass/NiFe/Co/Cu/Co/NiFe/NiMn/Ta stack were made by do magnetron sputtering. After deposition, the structure was annealed in a series of cycles each including three hours at $220^\circ C, 2\times10^{-6}$ Torr, in a field of 350 Oe, to create an ordered antiferromagnetic structure in the NiMn layer and produce a strong unidirectional pinning field in the pinned magnetic layer, Optimum spin valve properties were obtained after seven annealing cycles, or 21 hours at $220^\circ C$, and were : MR ratio 1%, exchange coupling field 620 Oe, and coercivity of pinned layer 250 Oe. The exchange coupling field remained constant up to an operating temperature of $175^\circ C$, and the blocking temperature was about $380^\circ C$.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.86-92
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• 2010

A metal diaphragm compressor has been widely used for supplying a high pressures gas. This compressor mainly consists of gas oil space and metal diaphragm. Gas sucked in the gas space is compressed by an oscillating metal diaphragm existed between the gas and oil space. A non-return discharge and suction check-valve are components of the compressor that draw off the compressed oil and gas. Those components are self-actuated by differential pressures. Therefore, the rapid response and stable operating conditions are required. In the present study, to find out the dynamic behavior of the suction, discharge valve and diaphragm compressor, the unsteady flow field has been investigated numerically by using the unsteady two-way FSI (Fluid Structure Interaction) simulation method, $k-{\omega}$ turbulent model and mesh deformation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.5
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• pp.767-773
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• 2013

A high-pressure, high-pressure drop control valve, which transforms the power transfer of a system by reducing the inlet pressure of 345bartothe outlet pressure of 112bar, is a fundamental component in an offshore plant process. With the increasingly growing market share of the maritime industry, this valve has been expected to be a high-value-added product. This study not only analyzes the relation between pressure drop and fluid velocity in a trim by using fluid analysis, but also examines the possibility of cavitation in a valve in addition to the plot for the extension of lifespan. Based on the analysis results, the design and production method of the valve are established, and accordingly, performance evaluation is carried out. It is demonstrated that the pressure drop from 345bar to 112bar is more feasible in the presence of the trim, which can induce a continuous and diminutive pressure drop in order to prevent cavitation in a high-pressure drop control valve. Furthermore, despite the fluid velocity near a seatring being found to be over 30m/s, the lifespan of the valve is determined to be adequate considering the operation condition of a prototype valve of 80%.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2247-2249
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• 2005

1970년대 이후 반도체 기술의 발달로 Thyristor Valve 가 기존의 Mercury Arc Valve를 대체 하면서 HVDC 기술이 급격히 향상되고 교류송전에 비해 직류송전이 갖는 여러 가지 이점 때문에 최근 HVDC 송전이 점점 증가하고 있는 추세에 있다. 본 연구에서는 2000년에 발표된 CIGRE 189.의 "800kV급까지의 HVDC 송전케이블의 전기적 평가 권고안" 에 준하여, 제조된 케이블의 전기적 평가를 위한 고전압 임펄스 중첩회로를 모듈별로 구성하고 그 회로의 동작을 시뮬레이션 프로그램으로 모의하고 전기적 시험회로의 구성가능성을 평가하였다.

• Journal of Magnetics
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• v.6 no.4
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• pp.145-147
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• 2001

The effect of interface roughness between [Ni/Mn] superlattice and pinned NiFe layer on magnetoresistance (MR) of [Ni/Mn] superlattice-based spin valve films was investigated. Antiferromagnetic phase structure and interface roughness of [Ni/Mn] superlattice spin valve films were compared in the as-deposited and the annealed samples at 240$\^{C}$, respectively. Surface morphology of spin valves was substantially flattened due to the formation of the antiferromatic NiMn phase. In case of Co insertion between Cu and NiFe, the interlace roughness and MR ratio in the annealed [NiMn] superlattice and pinned NiFe/Co layer increased more than those in the annealed [Ni/Mn] superlattice and pinned NiFe layers respectively.

• Journal of the Korean Institute of Gas
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• v.10 no.4 s.33
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• pp.23-28
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• 2006

This paper presents the strength safety and the weight reduction analysis of nine gas valve models for a LPG cylinder using a finite element analysis program, MARC and Taguchi's experimental method. The maximum Von Mises stress of a gas valve body represents a safety of a brass valve structure for the given gas pressure of $91kg/cm^2$, which considered a safety factor of a LPG gas cylinder. The weight reduction analysis is very important for reducing a gas flow friction loss and a manufacturing cost as a design parameter. The calculated results present an design model 9 as an optimized design data with 10mm radius of a lower part gas flow pipe A, 6mm radius of an upper part gas flow pipe B and a connecting length 2 mm of tapered pipe D between lower and upper pipes.