• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.146.2-146.2
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• 2008

• Journal of Chest Surgery
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• 제46권2호
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• pp.124-129
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• 2013

Background: Mitral valve repair for posterior mitral leaflet (PML) prolapse has been considered to be a standard treatment because of its high success rate and high level of patient satisfaction. The aim of this study was to evaluate the clinical results of two different techniques of PML prolapse, quadrangular resection (QR) and chordal replacement (CR). Materials and Methods: The subjects consisted of 56 patients who had undergone mitral valve repair for PML prolapse between November 1997 and December 2010. The patients were divided into two groups according to surgical technique. Among them, 31 patients underwent QR (group QR) and 25 patients had CR (group CR). We reviewed the medical records of the patients retrospectively to compare the clinical outcomes of both groups. Results: After mitral valve repair, the degree of mitral regurgitation (MR) in both groups decreased to the to a mild degree or less and the amount of remnant MR was slightly higher in the CR group but it was not statistically different. Three patients received mitral valve-related reoperation (2 in the QR group and 1 in the CR group). Freedom from mitral valve-related reoperation at 7 years was 93% for the QR group and 96% for the CR group and was not significantly different between the two groups. Conclusion: Both QR and CR showed excellent long-term results and were considered equally effective methods for PML prolapse.

• Journal of Chest Surgery
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• 제31권11호
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• pp.1031-1036
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• 1998

연구배경 : Medtronic-Hall 기계판막은 세계적으로 흔히 쓰이고 있으나, 우리 나라에는 그에 대한 임상연구가 되어 있지 않다 재료 및 방법 : 1986년 3월부터 1990년 5월까지 Medtronic-Hall 기계판막을 이용한 인공 심장판막 치환 환자 50례를 대상으로 하였다. 환자의 평균 연령은 35세였고 남녀비는 17:33이었다. 결과 : 판막 병변의 원인은 류마티스성이 43례로 대부분을 차지했고 38명의 환자에서 승모판 치환술을 7명에서 중복판막치환술을 그리고 5명의 환자에서 대동맥판막 치환술을 시행하였다. 술전 NYHA 기능 분류는 Class III 혹은 Class IV가 91.5%였지만 술후는 ClassI혹은 Class II가 87.2%로 호전된 양상을 보였다. 심장초음파 검사상 좌심방내경, 수축말기 및 확장말기 좌심실내경은 술후 모두 감소하였고 심박출률은 증가하였다. 술후 합병증은 출혈 3례, 저심박출 증후군 2례, 혈전색전증 1례, 전격성 간염 1례가 있었고 병원 사망례는 3례였다. 혈전색전증의 발생률은 1.5%/환자.년이었고 5년 생존률은 93.65$\pm$0.71%, 10년 생존률은 88.27$\pm$6.4%였다. 결론 : 이상에서 Medtronic-Hall 기계판막은 판막에 관련된 합병증 발생률이 낮고 판막의 내구성도 뛰어나며 혈역학적 수행능력이 타 기계판막에 뒤떨어지지 않는 판막으로 확인되었다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.147.1-147.1
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• 2008

• 한국인터넷방송통신학회논문지
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• 제12권2호
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• pp.77-83
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• 2012

진공 시스템의 성능에 대한 밸브 컨덕턴스의 영향은 진공시스템의 설계 최적화를 위해 전산모사 되었다. 본 연구에서는, 전산모사기인 VacSimMulti에 의한 모델링기구가 제시되었다. 진공 시스템의 설계는 진공 장비의 다양한 산업적 구현을 위해 특정한 프로세스 조건을 충족해야 한다. 진공 밸브의 구조, 길이, 직경 등은 컨덕턴스 영향의 전산모사 변수로서 모델링 되었으며, 직렬 진공 시스템의 배기 밸브 또한, 다양한 크기와 구조로 모델링하여 전산모사되었다. 밸브 직경의 변화는 도관의 길이의 변화보다 진공특성에 있어 더 유의미한 효과를 보여주었으며 슬릿형의 밸브도관 시스템은 모델링된 밸브구조 중 가장 뛰어난 진공특성을 가지는 것으로 관찰 되었다.

• 한국전산유체공학회지
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• 제21권4호
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• pp.54-60
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• 2016

The valve used in nuclear power plant must be qualified but the limitation of the test facility leads to use the numerical analysis. The flow coefficient is calculated with the consideration of the pressure, velocity and geometry. And the flow coefficient is the important physical property which is prepared using experiment or analysis by valve manufacturer. In this study, the analysis model was made according to ISA 75.02.01 and the mass flow rate and pressure drop ratio was calculated. The model of the expansion factor was applied to the simulation result and the pressure drop ratio at the start of the choked flow in the valve was found. With the simulation result, the consideration was performed that the expansion factor is the important physical property to the system engineer in addition to the flow coefficient.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.237-240
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• 2004

Sulfur Hexafluoride, SF6 is widely used for leak detection and as a gaseous dielectric in transformers, condensers and circuit breakers. SF6 gas is also effective as a cleanser in the semiconductor industry. This paper presents a numerical study of the sealing force of disk type seal in SF6 gas safety valve. The sealing force on the disk seal is analyzed by the FEM method based on the Taguch's experimental design technique. Disk seals in SF6 gas safety valve are designed with 9 design models based on 3 different contact length, compressive ratio and gas pressure. The calculated results of Cauchy stress and strain showed that the sealing characteristics of Teflon PTFE is more effective compared to that of FKM(Viton), which is related to the stiffness of the materials. And also, the contact length of the disk seal is important design parameter for sealing the SF6 gas leakage in the safety valve.

• Journal of Mechanical Science and Technology
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• 제18권6호
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• pp.1019-1025
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• 2004

Pressure variation is one of the major sources on noise emission in the axial type oil piston pumps. Therefore, it is necessary that the pressure variation characteristics of the oil hydraulic piston pumps be clarified to reduce the pump noise. Pressure variations in a cylinder at the discharge region and the pump noise were simultaneously measured with discharge pressures and rotational speeds during the pump working. To investigate the effects of the pre-compression and the V-notch in the valve plate, we used the three types of valve plates. In this research, it is clear that the pressure variation characteristics of axial type oil piston pumps is deeply related to the pre-compression and to the V-notch design in valve plate. Therefore, we could reduce the pump noise by using the appropriate pre-compression angle and the notch design that are between the suction port and the discharge port in valve plate.

• 한국항공우주학회지
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• 제43권11호
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• pp.1028-1034
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• 2015

발사체에 적용되는 솔레노이드 밸브의 경우 산업용 솔레노이드 밸브에 비해 엄격한 전류 및 무게, 크기 제한 조건을 요구한다. 이러한 제한 조건을 만족하며, 솔레노이드 밸브의 작동을 보장하기 위한 추진제탱크 가압제어용 솔레노이드 밸브 설계를 수행하였다. 극저온 상태에서 솔레노이드 전류 상승을 방지하기 위해 구리와 콘스탄탄 재료를 사용한 새로운 형태의 코일 설계를 적용하였으며, 시제품을 이용한 시험결과 측정된 전류는 설계 규격을 만족하고 있다.

• 한국기계가공학회지
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• 제17권1호
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• pp.144-152
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• 2018

The cleanability of machine parts is becoming increasingly important in the industrial field. In particular, cleanability is the most important factor in hydraulic products. The burr and chips are dominant factors of cleanability. If the burrs are not removed completely before the beginning of the machining stage, this will cause many problems, such as scratches and operation failure. Due to the complexity of the valve body itself, it is very difficult to use common deburring tools. In this study, a brush-like deburring tool was suggested and verified as a proper tool for removing the burrs and forming a proper edge shape through a real experiment. Various kinds of brush materials and process conditions were tested for proper deburring of the valve body. It was shown that the suggested method was successful for valve body deburring.