• Title/Summary/Keyword: Body valve

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A Study on the Stress and Deformation Behavior of an Alarm Valve using Finite Element Method (유한요소법을 이용한 알람밸브의 응력 및 변형거동에 관한 연구)

  • Kim, Chung-Kyun;Kim, Tae-Hwan
    • Journal of the Korean Institute of Gas
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    • v.16 no.2
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    • pp.14-17
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    • 2012
  • The stress and deformation behavior of an alarm valve has been analyzed using a finite element method. The strength safety of an alarm valve is calculated for the given maximum test pressure of 2.0MPa. The FEM computed maximum stress of an alarm valve is only 6.1% of yield strength, 370MPa and 4.6% of tensile strength, 485MPa, which are occurred at the corner part between a cover flange and a valve body. And the maximum deformation of $12{\mu}m$ was developed at the middle part of an alarm valve. These results mean that a typical alarm valve was designed with a excessively high strength safety, which may lead to an increase of a weight and a dimension.

Design of a Hydraulic System for a Power Split type CVT (동력분기식 무단변속기의 유압구동부 설계)

  • 김정윤
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.1
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    • pp.168-173
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    • 2004
  • This article describes the design of a hydraulic system for a power split type continuously variable transmission (CVT). The CVT considered here, is composed of planetary gears, clutches, and a torque converter which is mainly used for the realization of CVT function. Similar to automatic transmissions, the hydraulic system of CVT is designed for supplying hydraulic flows and pressures to each component of CVT, in order to activate the clutch engagements and torque converter operation, and to cool the drivetrain. By using the mathematical models of drivetrain, a simulation program was developed to investigate the power performance of CVT equipped vehicle and the operating conditions of each component of CVT. And the design parameters of the hydraulic system and clutches were calculated using the operating conditions and power requirements which obtained from the simulation results. Finally the hydraulic circuit design of prototyped valve body is presented based on the numerical results of this analysis.

Surface Lay Effects on the Lubrication Characteristics in the Valve Part of a Swash-plate Type Axial Piston Pump (표면가공무늬가 사판식 액셜 피스톤펌프의 밸브부 윤활특성에 미치는 영향에 관한 연구)

  • Shin, Jung-Hun;Kang, Bo-Sik;Kim, Kyung-Woong
    • Tribology and Lubricants
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    • v.28 no.1
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    • pp.12-18
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    • 2012
  • This application study of a swash-plate type axial piston pump was concerned about the lubrication characteristics between cylinder barrel and valve plate which are the main rotating body and its opposite sliding part respectively. A computer simulation was implemented to assess bearing and sealing functions of the fluid film between cylinder barrel and valve plate. A numerical algorithm was developed to facilitate simultaneous calculations of dynamic cylinder pressure, 3 degree-of-freedom barrel motions considering inertia effect, and fluid film pressure assuming full fluid film lubrication regime. Central clearance, tilt angle, and azimuth angle of the rotating body were calculated for each time step. Surface waviness was found to be an influential factor due to the small fluid film thickness which can appear in flat land bearings. Five surface lays which can form on the lubrication surface in accordance with machining process were defined and analyzed using the simulation tool. Oil leakage flow and frictional torque in the fluid film between cylinder barrel and valve plate were also calculated to discuss in the viewpoint of energy loss. The simulation results showed that in actual sliding conditions proper surface non-flatness can make a positive effect on the energy efficiency and reliability of the thrust bearing.

Mitral Valve Replacement in Children Less Than 16 years of Age (소아에서의 승모판치환술)

  • 이흥렬;홍유선
    • Journal of Chest Surgery
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    • v.29 no.10
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    • pp.1090-1094
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    • 1996
  • From February 1980 to September 1995, 31 children between 2 months and 15 years of age with mitral valve disease have undergone mitral valve replacement(MVR) at Yonsei Cardiovascular Center and com- plete follow-up has been obtained on 28 patients. There were 10 males and 18 females whose weight ranged from 4.9kg to 56kg. Two patients died early postopeiatively and the overall hospital mortality rate was 7.1%. These two were infants but there were no statistically significant difference in overall mortality among the age groups(p=0.13). The valve related complication rate was 57.1% in children younger than 5 years of age, which showed higher complication rate compared to older patients(p< 0.05). The bioprosthetic valve have been applied in 7 patients, and its 5-year valve failure-free survival rate was 50% . No mechanical valve failu e had occurred in 21 patients. In considering high re-replacement rate of bioprosthetic valve, mechanical valve is recommended despite its possibility of bleeding and thromboembolic complications. However, the consequences of increasing body size and long-term interposition of a rigid prosthesis in a growing heart will require second valve replacement. En conclusion, mitral valve replacement can be performed tilth satisfactory long-term survival in children, although younger mean age of the children has an important influence on early mortality and com- plication rate. And therefore mitral valve replacement in children younger than 5 years of age needs special consideration.

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Surgical Treatment of Heart Disease: II. Acquired Heart Disease I: Valve Replacement (심장질환의 외과적 요법에 관한 연구: II.후천성 심장질환, 1. 판막대치 이식수술)

  • Lee, Yung-Kyoon;Seo, Gyeong-Pil
    • Journal of Chest Surgery
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    • v.10 no.2
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    • pp.315-326
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    • 1977
  • From 1958 to October 1977, 294 cases of acquired heart disease were operated. There were 68 cases of pericardium, 3 trauma, 2 foreign body, one cardiac thrombus, 3 atrial myxoma, 2 left atrial and 1 right atrial, 2 Budd-Chiari syndrome, and 214 valvular heart disease. Out of 214 cases of valve operation 73 valves were replaced in 64 patients. Male to female ratio was 1.46: 1. The youngest age was 14 years in male and 18 in female. The oldest was 54 years in male and 52 in female. Fifty-five cases of single valve were replaced, consisting of 47 mitral and 8 aortic valves. There were 9 double valve replacement cases which consist of 7 mitral and aortic and 2 mitral .and tricuspid valves. Six varieties of prosthetic valves, 3 ball and 3 disc types and 3 kinds of xenograft tissue valves were utilized. Beall, BjSrk-Shiley and Starr-Edwards prosthetic valves and Hancock valves were used mainly. For single valve 34. 5% and for double valve replacement 44% mortality were noted. There were 23 operative deaths out of 64 patients, over all mortality rate of 36.9%. Mortality for mitral valve replacement was 29.5%. But in recent 12 consecutive cases one death occurred, showing 8.3% mortality. In earlier days thrombocyte anti-adhesive drug dipyramidole-persantin-aspirin and/or SP 54 were adminstered. But in recent cases after heparinization, coumadin and Persantin were prescribed routinely.

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The Effect of In-Outlet Differential Pressure on a Valve Body Stress and Deformation by the Blow-by Gas Flow Characteristic in the PCV valve for Automobile (자동차용 PCV밸브내 유통특성에 의한 밸브응력 및 변형에 미치는 입출구 차압의 영향)

  • Kwon Oh-Heon;Lee Yeon-Won;Song Sang-Min;Lee Jong-Hoon;Kang Ji-Woong
    • Journal of the Korean Society of Safety
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    • v.20 no.1 s.69
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    • pp.36-41
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    • 2005
  • PCV(Positive Crankcase Ventilation) valve acts as a flow control valve to get a re-combustion of blow-by gas by having it flow from a crankcase to an inlet manifold suction tube. The blow-by gas of the crankcase should be eliminated or taken properly because it cause corrosion to critical parts, and contributes to increase crankcase pressure that can cause a drop in efficiency. The excessive stress and strain on the PCV valve that remove these harmful gas would be bring the difficult on the flow rate control and failure of the valve. Those condition inevitably induce the accident. Therefore, this study purpose is FEM evaluation of the stresses and deformation in the X3 PCV model according to the change of the differential pressure between inlet and outlet. From results, the maximum equivalent stresses increased linearly according to the increase of the differential pressure at the about 50mm from the inlet position and were under the yield strength of the valve. And the deformations were relatively small regardless of the in-outlet differential pressure variation.

Integrative taxonomic description of two new species of the Cocconeis placentula group (Bacillariophyceae) from Korea based on unialgal strains

  • Jahn, Regine;Abarca, Nelida;Kusber, Wolf-Henning;Skibbe, Oliver;Zimmermann, Jonas;Mora, Demetrio
    • ALGAE
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    • v.35 no.4
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    • pp.303-324
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    • 2020
  • Cocconeis coreana and C. sijunghoensis are described as new based on micromorphological and molecular data. C. coreana is represented by five unialgal cultures from four different freshwater bodies, two from North Korea and three from South Korea. C. sijunghoensis is represented by two unialgal cultures from a brackish water body in North Korea. Except for one, all of the strains auxosporulated and showed an almost quadrupling of size in length and width. Morphologically, these species with their two different elliptical valves belong to the Cocconeis placentula group. The raphe valve has striae with uniseriate areolae continuing across a pronounced submarginal hyaline rim to the edge of the valve. The sternum valve has uniseriate dash-like areolae continuously from the valve face until the valve edge. Micromorphologically, these species possess two different open valvocopulae: only the raphe valvocopula has fimbriae; the sternum valvocopula has none. Based on p-distances of currently available DNA sequence data, i.e., rbcL and 18SV4, both species are pronouncedly different from the epitype strain of C. placentula, with C. coreana closest to the published molecular data of the strain UTEX FD23 named C. placentula from Iowa, USA, while C. sijunghoensis is closest but not the same as the published molecular data of strain D36_012, the epitype strain of C. placentula from Berlin, Germany. Based on scanning electron microscope observations, differentiating features are discussed concerning valvocopula fimbriae, central area, areolation of the sternum valve and on the raphe valve especially between the submarginal hyaline rim and edge.

Research on the on-site Seat Test Technology for the nuclear safety related valves (원전용 안전등급 밸브의 현장 폐쇄기밀시험 기술에 대한 연구)

  • Jung Hwan Seok;Kim Tae Sung
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.17 no.1
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    • pp.8-17
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    • 2021
  • The seat leakage test is required after the maintenance work on the valve seat. Either the test has been performed outside of the plant after cutting the valve from the pipe system or the simplified test has been performed so far. It was unable to perform the test at the plant site because it is hard to make a steady pressure on the valve inlet when it is installed in the pipe. This research aims to perform the leakage test in the nuclear power plant while it is installed in the pipe system. The mock-up test is performed by pressurizing the leak-off pipe on the valve body. The result is compared with traditional test result by pressurizing the valve inlet. Furthermore the chamber mock-up tests are performed under various conditions. The leak rate by the developed test using the leak-off pipe is found to be similar but greater than the leak rate by the existing test method. It implies that the test using the leak-off pipe is more conservative than the existing test. The methodology and the equipment which this paper suggests that on-site seat test is possible and the application of the technology could reduce the time and cost for the valve maintenance work significantly.

Design and Test Rig Construction for Piezoelectric Pump having Sheet Type Check Valve (시트 체크밸브를 갖는 압전펌프 설계 및 펌프 실험장치 제작)

  • 함영복;유진산;윤소남;최성대
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1442-1445
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    • 2003
  • In precision machinery industry, it's required with small size and low noise design to using in constant liquid delivery equipment. To accomplish it's purpose, we designed the check valve with rubber sheet of circle shapes as a possible assembly in pump body. The test equipment for piezoelectric pump was able to test pressure-flow property and output property of piezoelectric pump by variation(magnitude of voltage and frequency) of input power.

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A Study of Earthquake Design Air Operated Valve Actuator in Nuclear Power Plant (원자력 발전소 AOV 구동기 내진 설계에 관한 연구)

  • Kim, Y.B.;Jang, H.;Yoon, I.S.;Kang, Y.M.
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.485-490
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    • 2008
  • Under localization developing for the control valve of the safety grade Q Class 1 which is established in the atomic power plant followed ASME Code and important parts (Body, Yoke, Bonnet, Actuator) design and produced. In order to verify this analyzed the earthquake stress of AOV. AOV the above of 33Hz occurred from fIrst mode, the earthquake stress occurred from inside the yield strength of the material.

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