• 한국생산제조학회지
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• 제25권3호
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• pp.171-176
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• 2016

Growing concerns about air pollution have led to increased demand for liquefied natural gas (LNG)-fuelled ships that have crankcases equipped with explosion relief valves to relieve excessive crankcase pressures and stop the flames emitted from the crankcase. The results of a computational fluid dynamics (CFD)-based feasibility analysis of the crankcase relief valve flame arrester design conducted using ANSYS CFX V14 showed that the inlet and outlet relief valve temperatures differed by $350-700^{\circ}C$. An explosion test was performed based on European standard EN14797 to evaluate the flame transmission and mechanical integrity of the valve. No flame transmission from the pressure vessel to the exterior was detected, and the mechanical integrity of the valve was confirmed. Thus, the relief valve components were found to be safe from the viewpoint of fracture.

• Journal of Chest Surgery
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• 제25권11호
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• pp.1346-1353
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• 1992

From Febrary 1984 to July 1992, 138 cases of multiple valve replacements were performed at the Department of Thoracic and Cardiovascular Surgery, Dongsan Medical Center, Keimyung University. There were 81 females and 57 males, and their ages ranged from 19 to 60 years [mean age, 40.1$\pm$10.9 years]. Thirteen of these patients had undergone previous cardiovascular procedures, with an average of 76.3 months between procedures[range, 3 to 180 months]. Mitral and aortic valve replacement were done in 135 patients, 2 underwent triple valve replacement and 1 underwent mitral and tricuspid valve replacement. Associated procedures were necessary in 20 patients[14.5%]. The operative mortality was 5.8% and the most common cause was low cardiac output. Late follow-up of 83% has been accomplished in 130 early survivors, with a late mortality of 5.9%. The late mortality was due to valve thrombosis in 2 patients, cerebral infarction in 1, heart failure in 1, arrhythmia in 1, and bleeding in l. Of those patients who survived, New York Heart Association functional class improved significantly[from 70% class III and IV before to 88% class I and II after]. Actuarial survival rate including all deaths was 88.8% at 8 years. The follow-up studies revealed that thromboembolism, reoperation and bleeding rate were 1.2%/patient-year, 0.85% /patient-year and 0.57%/patient-year at 8 years postoperatively. We concluded that valve thrombosis, embolism, and anticoagulant-related hemorrhage were the main risk factors of longterm survival of patients.

• Journal of Chest Surgery
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• 제27권8호
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• pp.664-668
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• 1994

A total of 217 patients underwent single mitral valve replacement [MVR] with the St. Jude Medical valve between September 1984 and the end of 1992. There were 86 males and 131 females with a mean age of 34.6 $\pm$ 14.4 years[range 5 months-61 years]. A previous valve replacement had been performed in 46 patients [21.2 %]. An early mortality rate was 7.4 % [5.2 % in primary MVR; and 15.2 %in re-replacement MVR]. Early survivors of 201 patients were followed up for a total of 934.5 patient-years[mean 4.7 $\pm$ 2.1years]. A late mortality rate was 2.5 % or 0.54%/patient-year. The linearized rates of thromboembolism, valve thrombosis and anticoagulation-related bleeding were 1.301 %, 0.214 % and 0.428 %/patient-year, respectively. The actuarial survival including operative mortality was 89.9 % $\pm$ 2.1% at postoperative 10 years. The freedom from thromboemolism was 91.3 %$\pm$ 2.5% and the actuarial estimate of incidence free from late deaths and all complications were 80.9 % $\pm$ 3.8 % at 10 years. There were no mechanical failures. In summary, the St. Jude Medical prosthesis performed satisfactorily with an acceptable rate of late complications.

• Journal of Chest Surgery
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• 제51권2호
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• pp.149-152
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• 2018

A 76-day-old infant weighing 3.4 kg was referred for surgical intervention for severe mitral valve stenoinsufficiency caused by leaflet fibrosis and calcification. He had ex perienced a cerebral infarction in the left middle cerebral artery territory, which was deemed attributable to an embolism of a calcified particle from the dysmorphic mitral valve. Because mitral valve replacement using a prosthetic valve was not feasible in this small baby, mitral valve replacement with a pulmonary autograft was performed. After a brief period of extracorporeal membrane oxygenation (ECMO) support, he was weaned from ECMO and was discharged home without further cardiovascular complications.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.170-176
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• 2009

Flow control butterfly valve(FCBV) is known to have difficulty in controlling flow rate along valve opening due to its high flow rate. In low opening condition, the butterfly valve also has some shortcomings such as noise, vibration and erosion which are mostly caused by cavitation effects. Therefore, the FCBV requires proper remedies to reduce cavitation effects and to improve flow control performance. Numerical analysis is applied to FCBV flow to find effects of design factors such as seat diameter and valve opening rate. Cases with 3 different sizes of seat diameter and various valve opening rate are selected for the numerical analysis. From the analysis results, it is found that the FCBV with small seat diameter shows better pressure loss performance and reduced cavitation effects.

• 한국자동차공학회논문집
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• 제6권3호
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• pp.78-87
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• 1998

A dynamic model of direct-acting OHC valve train system has been used to determine the load conditions in the system. The modified equations for calculating the friction forces between cam and HLA, and at a camshaft bearing have been defined considering the lubrication conditions. Then, to understand the frictional characteristics in the system, a parameter study has been performed. As the results of the analysis, valve spring stiffness and preload have great effects on the friction in the system, but the effects of other parameters are negligible. So, how to design the valve train system with respect to the reduction of friction is to minimize the valve spring stiffness and preload in the limit of satisfying the dynamic constraints.

• 한국전산유체공학회지
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• 제15권1호
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• pp.64-70
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• 2010

Flow control butterfly valve(FCBV) is known to have difficulty in controlling flow rate along valve opening due to its high flow rate. In low opening condition, the butterfly valve also has some shortcomings such as noise, vibration and erosion which are mostly caused by cavitation effects. Therefore, the FCBV requires proper remedies to reduce cavitation effects and to improve flow control performance. Numerical analysis is applied to FCBV flow to find effects of design factors such as seat diameter and valve opening rate. Cases with 3 different sizes of seat diameter and various valve opening rate are selected for the numerical analysis. From the analysis results, it is found that the FCBV with small seat diameter shows better pressure loss performance and reduced cavitation effects.

• 동력기계공학회지
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• 제2권3호
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• pp.34-40
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• 1998

Performance characteristics of a refrigeration systems with various expansion valves and superheat changes were investigated experimentally. Experimental data have been taken utilizing three different devices; a thermostatic expansion valve, a linear type electronic expansion valve and a solenoid type electronic expansion valve. The data taken from tile three types of expansion valves were discussed with the temperature distribution of each zone in the evaporator and the superheat changes of the evaporator outlet In each zone temperature distribution fluctuated larger with the thermostatic expansion valve than with the electronic expansion valves. The optimum superheat ranged from $5^{\circ}C\;to\;15^{\circ}C$, and the superheat with the thermostatic expansion valve showed hunting phenomenon, which affected the evaporating and condensing temperature.

• Tribology and Lubricants
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• 제14권4호
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• pp.23-28
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• 1998

To increase the efficiency of the hydraulic axial piston pumps, it is need to know the various characteristics in the sliding contact parts of them. Especially, friction characteristics between the cylinder block and the valve plate in the hydraulic axial piston pumps plays an important role to high power density. In this paper, we tried to clarify friction characteristics between the cylinder block and the spherical valve plate in bent-axis-type axial piston pump in experimentally. Results are arranged as follow; (1) friction torque between the cylinder block and the spherical valve plate has a proportional relation to weight or rotational speed, and is strongly affected by temperature. (2) Friction torque strongly depends on force balance ratio in valve plate. (3) In this experiment, lubrication condition between the cylinder block and the spherical valve plate is under hydrodynamic lubrication.

• Journal of Chest Surgery
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• 제10권1호
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• pp.156-163
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• 1977

This is a report of a case in which mitral valve replacement was performed using Starr-Edwards ball valve [model 6230] by total cardiopulmonary bypass with total hemodilution prime and moderate hypothermia. The patient was 21 year old girl, and mitral valvular symptoms occurred 5 years ago. According to clinical features of the disease, the patient was classified as the class IV of N.Y.H. A. cla3sification. The preoperative diagnosis of mitral insufficiency was made mainly by left ventriculography of roentgenologic study. The mitral valve was highly deformed due to scar contraction of valve leaflets and shortening of chordae tendineae. After prosthetic valve replacement, no abnormal hemodynamic signs were observed. The postoperative course was uneventful.