• Journal of Chest Surgery
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• v.29 no.10
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• pp.1102-1110
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• 1996

Between Oct. 1985 and July 1995, 230 patients underwent mitral valve replacement. There were 77 men and 153 women whose mean age was 35.7 years, range 9 to 62 The concomitant operations were 40 aortic valve replacements(17.4%), 25 tricuspid annuloplasties(10.4%), 8 aortic valve replacements & tricuspid annuloplasties(3.5%), 2 tricuspid valve replacements(0.9%) and others, We used 139 mechanical (76 51. Jude medical, 33 CarboMedics, 30 Sorin) and 91 tissue 386 Carpentier-Edwards, 5 lonescu-Shiley) valves. The early postoperative complications occurred in 28 cases. There were 8 low cardiac output syndrome, 5 pleural effusion, 3 significant arrhythmia, 2 cardiac rupture and others. There were 6 early hospital deaths (2.6%) due to low cardiac output syndrome(2), arrhythmia(2) and ventricul r rupture(2). The cuAmulative notal follow-up period was 764. 4 patient-years with a mean of 4).9 months. The long term follow-up information was available for 212 patients(94.6%). There were 21 cases of valve-related complications. Prosthetic valve failure(10), anti-coagulation related bleeding (5), prosthetic valve endocarditis (4), and thromboembolism (2) occurred at rates of 1.3, 0.7, 0.5, and 0.3%Ipt-yr respectively. Late death occurred In 5 cases (0.7%/pt-yr) associated with prosthetic valve endocarditis (2), heart failure (2) and anti-coagulation related bleeding (1). There was no difference in the rate of freedom from prosthetic valve failure between the mechanical and tissue valve group at 6 years (100%), but there was significant difference at 9 years between the tissue (34.4%) and mechanical valve (100%) group (p=0.032). Actuarial survival rates were 98. 8% in tissue valve. 9).7% in mechanical valve group and 96.6% in total patients at 9 years.

• Journal of Chest Surgery
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• v.30 no.4
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• pp.390-395
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• 1997

Between May 1986 and May 1996, 269 patients underwent prosthetic valve replacement. A bioprosthetic valve was replaced in 70 cases and mechanical valve was replaced in 232. Of this 12 patients performed reoperations for replacement, and the mean interval between primary valve operation and reoperation was 87.6 months for mitral valve and )7.7 months for aortic valve. There were 10 women and 2 me , agcd from 22 to 68 years(mean 45). A bioprosthetic valve was implanted in 8 cases and a mechanical valve was implanted in 4 cases for initial operation. llidications for reoperation were structural deterioration in 5 cases(42%), valve thrombus in 5 cases(42%) and endocarditis in 2 cases(17%). Operations performed included 3 aortic valve replacements(25%), 9 mitral valve replacements(75%). Wc used mechanical valve in llcases(92%) and tissue valve in 1 case(8%) for reoperation. There were 2 early operative deaths because of valve detachment and of acute respiratory failure. Among ten survivor's, there were no late deaths with follow up of 35.8 months.

• Bulletin of the Korean Chemical Society
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• v.23 no.1
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• pp.75-80
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• 2002

Cycle life tests have been carried out to evaluate the influence of safety valve pressure on valve regulated lead/acid batteries under deep cycling applications. Batteries were cycled at 5 hour rates at 100% DOD, and safety valve pressure was set to 1.08 and 2.00 bar, respectively. The batteries lost 248.3 g and 235.3 g of water for each case after about 1,200 cycles, but the cyclic performances of the batteries were comparable. Most of the gas of the battery during discharging was hydrogen, and the oxygen concentration increased to 18% after 3 hours of charging. The micro structure of the positive active materials was completely changed and the corrosion layer of the positive grid was less than $50{\mu}m$, regardless of the pressure of the safety valve after cycle life tests. The cause of discharge capacity decrease was found to be water loss and the shedding of the positive active materials. The pressure of safety valve does not give little effect to the cyclic performances and the failure modes of the gelled electrolyte valve-regulated lead acid batteries.

• Industry Promotion Research
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• v.2 no.1
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• pp.9-13
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• 2017

This study deals with the check valve safety valve for residential gas piping. It can be manually shut off within 1 second in case of emergency, and it is possible to touch 3kg of pressure by hand force. To develop the technology so that it can be used repeatedly. Study results after first valve operation. And 0.61 seconds on average. Therefore, it was found that there was no problem in operation even when used as a safety valve. Third, it was found that all of the results of using the blocking ball diameter of 7mm were not abnormal. In this study, it is meaningful to develop the check valve safety valve of gas piping and verify the performance by testing with existing valve.

• Journal of Chest Surgery
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• v.27 no.10
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• pp.838-845
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• 1994

From April, 1982 to December, 1992, multiple valve replacement was performed in 100 patients. Mitral and aortic valve replacement were done in 86 patients, 9 underwent mitral and tricuspid valve replacement, 4 patients underwent triple valve replacement and 1 patient underwent aortic and tricuspid valve replacement. Of the valve implanted, 100 were St. Jude, 64 Duromedics, 19 Carpentier-Edwards, 13 Bj rk-Shiley, 6 Ionescu-Shiley, and 2 Medronics.The hospital mortality rate was 15%[15 patients] and the late mortality rate was 7%[7 patients], the mortality rate was high in early operative period but decreased with time[20% at 1986, 18.2% at 1987, 9.5% at 1988, 11.1% at 1989, 12.5% at 1990, 11.8% at 1991, 0% at 1992]. The causes of death were low cardiac output in 8, sudden death in 3, CHF in 3, bleeding in 2, cerebral thromboembolism in 1, leukemia in 1, multiorgan failure in 1 and so on. The actuarial survival rate excluding operative death was 73% at 10 years.

• Journal of Chest Surgery
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• v.23 no.4
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• pp.667-675
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• 1990

From June, 15th, 1987 to June, 14th, 1989, 105 Duromedics bileaflet cardiac valve prostheses were implanted in 81 patients. Mitral valve replacement was done in 42 patients, 7 underwent aortic valve replacement, 28 underwent double valve replacement, & 4 patients underwent triple valve replacement. Concomitantly used valves were 13 cases; 11 cases were St. Jude Medical valves[M: SJM #29 X4, #27 X5, #25 X 1, T: SJM #33] & two cases were Carpentier Edwards bioprostheses[T: C - E #31X2]. The early mortality rate[within 30 days] was 3.7%[2 patients] & the late mortality rate was 7.4%[3 patients]. Follow-up was done on 72 surviving patients; mean follow-up period was 21.17$\pm$5.36 months. Anticoagulant-related hemorrhage was observed in two patients, possible prosthetic valvular endocarditis was observed in one patient and other specific valve-related complications were none. We concluded, therefore, that good clinical results & a low complication rate could be achieved with Duromedics bileaflet valve in short-term follow-up, & long-term follow-up was also necessary.

• The KSFM Journal of Fluid Machinery
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• v.8 no.4 s.31
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• pp.7-13
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• 2005

Although the globe is the most typical valve to control high pressure drop in piping system, it is very hard to figure out the characteristics of flow field in the globe valve caused by its complex geometry, So there is very few studies to find out flow characteristics of globe valve. In this study numerical analysis for flow field in the globe valve is carried out using the FLUENT code which is commercial CFD program. Pressure drop through the globe valve is also measured to verify the results come from numerical analysis. Comparing experiment with numerical analysis, two results are very close to each other.

• Journal of Chest Surgery
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• v.27 no.6
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• pp.444-450
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• 1994

From June 1984 to February 1994, cardiac valve replacement was performed in 108 patients. The distribution of patients was ranged from 13 to 64 year-old age[mean 39.48 1.24] and 51 patients were male, 57 patients were female [male:female=1:1.1]. 64 patients had mitral valve replacement, 27 patients underwent aortic valve replacement and 17 patients were performed double[mitral & aortic] valve replacement. Total 125 artificial cardiac valves were used, mechanical valves were 51 valves and tissue valves were 74 valves. The duration of follow-up was 473.41 patient-year[mean 4.79 3.29 patient-year] and the information of follow-up was available for 99 patients[92%]. The actuarial survival rates including the operative mortality was 89.5% & 88.3 at postoperative fourth & ninth year. The probability of freedom from overall valve failure, thromboembolism and bacterial endocarditis were 77.5%, 89.2% and 95.6% at ninth year after cardiac valve replacement.

• Journal of Drive and Control
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• v.18 no.3
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• pp.23-29
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• 2021

Hydrogen energy is the clean energy source of the future. Ultra-high-pressure hydrogen is used in hydrogen stations, with its parts being developed. On the other hand, ultra-high-pressure ball valve, which is one of its parts, depends on overseas, with the level of domestic research on this being only about 10% of advanced technology research on this abroad. In this study, the shape of an ultra-high-pressure ball valve for a hydrogen station was designed to improve its structural strength. The valve body was designed according to distance between both processed body holes along inlet and outlet ports. The designed vale body was then analyzed using ANSYS to check whether points with stress were concentrated. In addition, the valve with improved body was analyzed to confirm that the valve satisfied the design condition.

• Journal of Chest Surgery
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• v.17 no.4
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• pp.678-686
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• 1984

Between Jan. 1978, and Dec. 1983, a total and consecutive 117 patients have undergone cardiac valve replacement using various artificial tissue valve. Out of 117 patients, single valve surgery was 78 consisted of MVR 74, AVR 3 and AVR & supracoronary ascending aorta replacement 1. Multiple valve surgery was 39 cases consisted of MVR+TAP 20, MVR+AVR 13 and so on. Early death with 30 days after operation was 12 cases [early mortality 10.3%] and causes of death were cardiac origin 5, technical problem 4, and others 3. The 105 early survivors were followed-up for a total of 190.5 years over a period of 2 to 64 months [Mean\ulcornerD:21.9\ulcorner4.9 months]. During follow-up, 7 cases died [late mortality:6.7%]. The rate of thromboembolism was 2.1% episodes per patient-year and bleeding due to anticoagulant was 3.1% episodes per patient-year and valve failure was 1.6% episodes per patient-year. Actuarial analysis of late results indicated an expected survival rate at 5 years of 84.6% for patients with single valve surgery and 82.1% for patient with multiple valve surgery and overall was 83.8%. Symptomatically, 86.7% of patients were in NYHA class I or II at the end of follow-up.