• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2005년도 연구개발 발표회 논문집
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• pp.437-440
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• 2005

In the present work, characteristics of the flow in CAGE of a steam turbine LP/HP Bypass control valve for thermal power plant are investigated. The flow field is analyzed numerically by solving steady three-dimensional Reynolds-averaged Navier-Stokes equations. Shear stress transport (SST) model is used as turbulence closure.

• Journal of Chest Surgery
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• 제27권3호
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• pp.187-190
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• 1994

Between March, 1989, and August, 1993, 10 patients underwent aortocoronary bypass surgery concomittant with cardiac valve replacement. They were 6 men and 4 women, the age ranging from 47 to 64. 7 patients underwent single valve replacement and 2 patients underwent double valve replacement, Another one patient underwent only CABG one year after valve replacement and he had no evidence of prosthetic valve failure. Total number of graft vessels were.15,14 were saphenous venous grafts and 1 was internal mammary artery graft. Dyspnea on exertion was frequent symptom and was found in all patients. 8 patients presented stable angina, only 1 patient presented postinfarct angina and another 1 patient presented no angina symptom. The graft was placed prior to valve replacement and periods of myocardial ischemia were kept at a minimum by maintaining coronary perfusion throughout operation. Postoperative course was uneventful and there was no hospital mortality, as was supported by many reports, it is our opinion that simultaneous valve replacement and aortotomy bypass graft does not increase the risk of cardiac valve replacement substantially.

• Journal of Chest Surgery
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• 제23권3호
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• pp.514-521
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• 1990

Patient with aortic valvular disease have increased left ventricular work and greater myocardial oxygen demand, which may aggravate the effect of concomitant coronary artery disease. Thus in patient who repair aortic valve replacement, concomitant aortocoronary bypass surgery is often performed when angiographically significant coronary artery disease is present. This approach is supported by reports that revascularization does not increase operative risk when associated coronary artery disease is present and significantly reduce the occurrence of late sudden death. Recently we have experienced one case of aortic valve replacement concomitant with aorta-coronary bypass surgery. The patient was 56 year-old male and admitted with complaint of anterior chest pain especially during his exercise. He was diagnosed as aortic valve stenosis and regurgitation [GIII] with proximal right main coronary artery occlusion We performed aortic valve replacement with aorta coronary bypass surgery by use of saphenous vein. Post operative course was uneventful and chest pain was relieved. Post operative coronary angiogram disclosed good patency of grafted vessel.

• 한국유체기계학회 논문집
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• 제10권6호
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• pp.17-23
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• 2007

In the present work, flow analysis has been performed in the steam turbine bypass control valve (single-path type) for two different cases i.e., case with steam only and case with both steam and water. The numerical analysis is performed by solving three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations. The shear stress transport (SST) model and $k-{\varepsilon}$ model are used to each different case as turbulence closure. Symmetry condition is applied at the mid plane of the valve while adiabatic condition is used at the outer wall of the cage. Grid independency test is performed to find the optimal number of grid points. The pressure and temperature distributions on the outer wall of the cage are analyzed. The mass flow rate at maximum plug opening condition is compared with the designed mass flow rate. The numerical analysis of multiphase mixing flow(liquid and vapor) is also performed to inspect liquid-vapor volume fraction of bypass valve. The result of volume fraction is useful to estimate both the safety and confidence of valve design.

• Journal of Chest Surgery
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• 제51권4호
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• pp.283-285
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• 2018

A 73-year-old woman who underwent combined bioprosthetic mitral valve replacement, tricuspid ring annuloplasty, and coronary artery bypass grafting 12 years previously visited our clinic due to aggravated dyspnea caused by structural valve deterioration of the mitral prosthesis. Because aortic or femoral artery cannulation and cross-clamping would have a high risk of stroke owing to severe calcification of the ascending aorta and ilio-femoral vessels, and because there was a risk of redo sternotomy due to the patent bypass grafts, a comprehensive approach including axillary artery cannulation, a minimally invasive right thoracotomy approach, and a clampless hypothermic fibrillatory arrest technique was used during redo mitral valve replacement.

• Journal of Chest Surgery
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• 제26권11호
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• pp.881-885
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• 1993

In the last few years there has been a resurgenceof interest in in-situ saphenous vein arterial bypass for lower extremity revascularization because of improved patency rates. we performed 1 in situ bypass oreration using the intraluminal valve-disruption tecnique. A 65-year-old female who had ztherosclerotic obstruction in the superficial and popliteal arteries underwent in situ saphenous vein arterial bypass. After harvesting of saphenous vein, we used LeMaitre retrograde valvulotome for valve-disruption technique. Completion of the arterrigraphy was performed to evaluate bothh the anastomoses. The two side brances were all ligated. In situ saphenous vein arterial bypass has become the procedure of choice for distal reconstruction in severely ischemic lower extremities because of improved long-term patency compared with reversed-saphenous vein bypass procedure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2558-2562
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• 2007

In the present work, flow characteristics analysis has been performed for steam turbine bypass control valve (single-path type). The numerical analysis is performed by solving three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations. Shear stress transport (SST) model is used as turbulence closure. Symmetry condition is applied at the mid plane of the valve while adiabatic condition is used at the outer wall of the cage. Grid independency test is performed to find the optimal number of grid points. The pressure and temperature distributions on the outer wall of the cage are analyzed. Mass flow rate at maximum plug opening condition is compared with the designed mass flow rate.

• Journal of Chest Surgery
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• 제46권5호
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• pp.380-382
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• 2013

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.181-182
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• 2010

• 한국항공우주학회지
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• 제41권2호
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• pp.85-90
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• 2013

비행조종작동기 제어용 파일럿 밸브의 내부 유동 및 응답 특성을 분석하기 위해 유동의 수치 해석을 수행하였고 내부 누설 특성을 해석하였다. 온도 변화에 따른 누설을 고려한 밸브의 작동온도를 결정할 수 있는 영역을 제안 할 수 있었다. 미량의 작동유체가 누설 영역으로 유출된다는 것을 확인하였으나 누설 효과는 작동 온도에 따라 영향을 미치지 않는 것을 확인하였다. 압력 상승률이 온도가 하강할수록 높아지는 경향을 나타냈다.