• 제목/요약/키워드: 2 Valve

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심장판막 이식에 관한 연구 (Cardiac Valve Replacement: A Report of 16 Cases)

  • 김주현;이영균
    • Journal of Chest Surgery
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    • 제8권2호
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    • pp.89-100
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    • 1975
  • Sixteen cases of cardiac valve replacements have been done in this department since 1970. Twelve cases of mitral valve replacement were done with Beall valve, 2 cases of aortic valve replacement with Starr-Edwards and Magoven valve and 2 cases of double valve replacement using Beall valve for mitral and Magovern valve for aortic. Three patients [18.8%] died during operation. Two cases [12.5%] of hospital mortality occurred because of congestive heart failure and asphyxia due to tracheomalacia 3 months after operation. Follow-up studies from two to 27 months showed excellent results except three cases of late mortality [18.8 %]. Thromboembolism occurred in two double valve replacement patients[12.5%]who were fatal.

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경식도 심초음파 검사를 이용한 판막대치술 환자의 평가 (Postoperative Transesophageal Echocardiographic Evaluation in Patients with Cardiac Valve Replacement)

  • 조건현
    • Journal of Chest Surgery
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    • 제24권3호
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    • pp.265-270
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    • 1991
  • Since advent of the prosthetic cardiac valve replacement, much efforts for accurate assessing value function in-vivo have been attempted. To evaluate the postoperative functional and morphological status of the replaced cardiac valve prosthesis, 33 patients with valve replacement were studied by transthoracic and transesophageal 2-dimensional echocardiac imaging as well as by color Doppler flow velocity imaging. Twenty four patients had mitral valve replacement. 6 patients had aortic valve replacement and 3 patients had both mitral and aortic valve replacement. There were 34 mechanical and 2 biological prosthesis. Comparing to transthoracic echocardiography, transesophageal approach showed transvalvular regurgitant jet flow amid the prosthetic mitral valve ring during. systole and much clear visualization of cardiac chamber behind prosthesis which could give shadowing effect to ultrasound beam. According to the quantitative grading by the length and area of mitral regurgitant flow, 24 out of 27 mitral valves revealed mild degree regurgitation considered as physiological after prosthetic bileaflet valve replacement and the other 3 valves including 2 biological prosthesis had moderate degree regurgitation which was regarded as pathologic one. 2 cases of left atrial thromboses and 1 case of paravalvular leakage which were not visible by transthoracic approach were identified by transesophageal echocardiography in patients with mitral valve replacement and patients with aortic valve replacement respectively. We conclude that in patients with prosthetic mitral valve replacement, transesophageal 2-dimensional imaging with color Doppler can suggest reliable information beyond that available from the transthoracic access even though it gives patient some discomfort to proceed.

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세라믹 밸브 인서트의 최근 개발동향 (Current design methodology for ceramic valve seat insert)

  • 이수완;이명호
    • 오토저널
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    • 제16권4호
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    • pp.1-5
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    • 1994
  • 1) Natural gas engine에서 intake valve와 valve seat insert가 exhuast valve와 valve seat insert보다 마모가 심하다. 2) Ceramic valve seat insert을 금속재료를 사용하는 것이 보다 더욱 효과적이다. 즉 적어도 3배 정도 마모가 적게 일어난다. 3) Ceramic valve와 ceramic valve seat insert로 결합한 경우 valve face 또는 stem 부위에서 응력이 집중되어 파손된다. 따라서 현재의 ceramic valve design methodology로는 ceramic valve은 좋은 결과를 얻을 수 없다. 4) 가장 효과적인 결합은 Tribolloy 800의 hardfacing 합금의 valve와 질화규소의 valve seat insert이다.

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심초음파도를 이용한 대동맥인공판막치수 예 (Two-Dimensional Echocardiographic Prediction of Prosthetic Aortic Valve Size)

  • 박창권
    • Journal of Chest Surgery
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    • 제20권4호
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    • pp.655-658
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    • 1987
  • Aortic annulus size was measured by two-dimensional echocardiography [2DE] in 29 patients undergoing aortic valve replacement or double valve replacement in order to predict prosthetic aortic valve size. Fifteen patients had aortic stenoinsufficiency, eleven had aortic insufficiency, and three had aortic stenosis. 2DE measurements of aortic annulus diameter, as determined from the parasternal long-axis view, demonstrated a high correlation with actual prosthetic valve size implanted at surgery [r=0.85, p<0.05]. 2DE exactly predicted actual prosthetic valve size in 8 of 29 patients [27.6%], was within 1mm of prosthetic valve size in 11 of 29 patients [37.9%], was within 2mm of prosthetic valve size in 8 of 29 patients, and was within 3mm of prosthetic valve size in 2 patients.

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인공 심장판막의 재치환술 -수술 위험인자와 수술 결과의 분석- (Reoperation of Prosthetic Heart Valve; An Analysis of Operative Risks and Late Results)

  • 김관민
    • Journal of Chest Surgery
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    • 제28권1호
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    • pp.23-30
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    • 1995
  • From January 1985 to December 1992, of 1257 patients who underwent a heart valve replacement 210 [16.8% underwent reoperation on prosthetic heart valves, and 6 of them had a second valve reoperation. The indications for reoperation were structural deterioration [176 cases, 81.5% , prosthetic valve endocarditis [25 cases, 11.6% , paravalvular leak [12 cases, 5.6% , valve thrombosis [2 cases, 0.9% and ascending aortic aneurysm [1 case, 0.4% . Prosthetic valve failure developed most frequently in mitral position [57.9% and prosthetic valve endocarditis and paravalvular leak developed significantly in the aortic valve [40%, 75% [P<0.02 . Mean intervals between the primary valve operation and reoperation were 105.3$\pm$28.4 months in the case of prosthetic valve failure, 61.5$\pm$38.5 months in prosthetic valve endocarditis, 26.8$\pm$31.2 months in paravalvualr leak, and 25.0$\pm$7.0 months in valve thrombosis. In bioprostheses, the intervals were in 102.0$\pm$23.9 months in the aortic valve, and 103.6$\pm$30.8 months in the mitral valve. The overall hospital mortality rate was 7.9% [17/26 : 15% in aortic valve reoperation [6/40 , 6.5% in reoperation on the mitral prostheses [9/135 and 5.7% in multiple valve replacement [2.35 . Low cardiac output syndrome was the most common cause of death [70.6% . Advanced New York Heart Association class [P=0.00298 , explant period [P=0.0031 , aortic cross-clamp time [P=0.0070 , prosthetic valve endocarditis [P=0.0101 , paravalvularr leak [P=0.0096 , and second reoperation [P=0.00036 were the independent risk factors, but age, sex, valve position and multiple valve replacement did not have any influence on operative mortality. Mean follow up period was 38.6$\pm$24.5 months and total patient follow up period was 633.3 patient year. Actuarial survival at 8 year was 97.3$\pm$3.0% and 5 year event-free survival was 80.0$\pm$13.7%. The surgical risk of reoperation on heart valve prostheses in the advanced NYHA class patients is higher, so reoperation before severe hemodynamic impairment occurs is recommended.

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인공판막 치환수술 재수술에 대한 임상적 고찰 -12예보고- (Clinical Analysis of Reoperation for Prosthetic Valve Replacement Report of 12 cases)

  • 장진우;이연재
    • Journal of Chest Surgery
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    • 제30권4호
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    • pp.390-395
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    • 1997
  • 1986년 5월부터 1996년 5원까지 총 269명(조직판막70례, 금속판막 232례)의 판막 치환술 환자중 판막의 재치환술이 필요했던 12례를 분석 하였다. 승모판 재치환술이 9례, 대동맥 판막 치환이 3례로 연령범 위는 16세에서 68세까지로 50대 이후가 가장 많았다. 초인공판막치환후 재 수술이 필요했던 숭모판막의 경우 평균 87.6개월, 대동맥판막의 경우 36.7개월로서, 대부분의 경우 운동시 호흡곤란이 주증상이었으며 원인으로서는 판막자체의 구조적 실패 5례, 심내막염 2례였으며 재치환술에 사용된 판막은 기계판막 11례, 조직판막 1례로 수술후 사망률은 17% (2/12)였고 술후 심내막염 및 폐렴에 의한 호흡부전으로 사망하였다.

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DME 예혼합 압축 착화 엔진에서 밸브 양정과 개폐시기가 내부 배기가스 재순환과 연소에 미치는 영향 (Effect of Valve Lift and Timing on Internal Exhaust Gas Recirculation and Combustion in DME Homogeneous Charge Compression Ignition Engine)

  • 장진영;배충식
    • 한국자동차공학회논문집
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    • 제17권4호
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    • pp.93-100
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    • 2009
  • Intake/exhaust valve timing and exhaust cam lift were changed to control the internal exhaust gas recirculation (IEGR) and combustion phase of homogeneous charge compression ignition (HCCI) engine. To measure the IEGR rate, in-cylinder gas was sampled during from intake valve close to before ignition start. The lower exhaust cam made shorter valve event than higher exhaust cam and made IEGR increase because of trapping the exhaust gas. IEGR rate was more affected by exhaust valve timing than intake valve timing and increased as exhaust valve timing advanced. In-cylinder pressure was increased near top dead center due to early close of exhaust valve. Ignition timing was more affected by intake valve timing than exhaust valve timing in case of exhaust valve lift 8.4 mm, while ignition timing was affected by both intake and exhaust valve timing in case of exhaust valve 2.5 mm. Burn duration with exhaust valve lift 2.5 mm was longer than other case due to higher IEGR rate. The fuel conversion efficiency with higher exhaust valve lift was higher than that with lower exhaust valve lift. The late exhaust and intake maximum open point (MOP) made the fuel conversion efficiency improve.

복합알람밸브의 강도안전성에 관한 유한요소해석 (Finite Element Analysis on the Strength Safety of a Hybrid Alarm Valve)

  • 김청균;김태환
    • 한국생산제조학회지
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    • 제21권2호
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    • pp.221-224
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    • 2012
  • This paper presents the strength safety of a hybrid alarm valve by a finite element analysis. The stress and strain of a conventional hybrid alarm valve are calculated for the given maximum test pressure of 2MPa. Especially, the FEM computed maximum stress of a conventional hybrid valve is only 18.6% of yield strength, 370MPa. This means that the conventional valve is designed with a thick thickness of a valve structure. But, new hybrid alarm valve model, which is developed by optimized design method in this study, shows more low level of 43% in maximum stress and strain compared with that of a conventional hybrid valve. These results may recommend the reduction of a weight and a dimension for an optimized hybrid alarm valve.

Cone Type 밸브 내부유동 수치해석에 관한 연구 (A Study on the Numerical Analysis of Internal Flow in a Cone Type Valve)

  • 진도훈
    • 한국산업융합학회 논문집
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    • 제23권2_2호
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    • pp.199-207
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    • 2020
  • These days, many different types of valves are developed in the industrial area according to their use purpose. Multiple kinds of valves are installed to control a flow and pressure of the pipe conveying fluid. Valves serve as critical roles in land plants such as power plants. The performance of equipment varies depending on valve characteristics. In this study, the internal flow analysis on Cone-type valve is conducted to analyze flow field and secure a value of the flow coefficient Cv. According to the internal flow analysis, when the flow distribution of the middle cross-section of valve was open 100%, flow field was relatively and smoothly taken out. If it was open 50%, flow recirculation region increased and a little complex flow field occurred. Unlike ball valve or butterfly valve, this valve had flow recirculation in its outlet depending on a valve opening amount. Therefore, it was found that there was no flow recirculation in the outlet of Cone-type valve.

인공심방판막실패에 대한 임상적 고찰 (Reoperation for prosthetic valve failure -clinical analysis of 15 cases-)

  • 권오춘
    • Journal of Chest Surgery
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    • 제19권4호
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    • pp.584-594
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    • 1986
  • Despite the multivariate improvements in tissue treatment, material, and design of prosthetic heart valves in recent years, numerous complications that may lead to valve dysfunction remain a constant threat after valve replacement. Most common indications for prosthetic valve failure are primary valve failure, infective endocarditis, paravalvular leakage, and thromboembolism. From 1977 to 1986, 15 patients underwent reoperation for prosthetic valve failure in 278 cases of valve surgery. The etiology of prosthetic valve failure were primary valve failure in 12 patients [80 %], infective endocarditis in 2 patients [13.3 %], and a paravalvular leakage [6.7 %]. The average durations of implantation were 45.5 months; 53.9 months in primary valve failure, 16 months in infective endocarditis, and 4 months in paravalvular leakage. The rate of valve failure was high under age of 30 [11/15]. Calcifications and collagen disruption of prosthesis were main cause of primary valve failure in macro- & micropathology. Prosthesis used in reoperation were 5 tissue valves and 10 mechanical valves. Operative mortality were 13.3 % [2/15], due to intractable endocarditis and ventricular arrhythmia.

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