• Journal of Chest Surgery
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• v.42 no.3
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• pp.361-363
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• 2009

A 17-year-old male patient was referred with symptoms of dyspnea. Multi-detector computerized tomography (MDCT) and echocardiography evaluation revealed quadricuspid aortic and pulmonary valves, an atrial septal defect (ASD), and pulmonary stenosis. We closed the ASD using a bovine patch and performed a commissurotomy of the pulmonary valve. Quadricuspid semilunar valves are very rare congenital abnormalities that are reported to occur nine times more frequently in the pulmonic valve than in the aortic valve. According to the Hurwitz Roberts classification, the aortic valve was type A, and the pulmonic valve was type B. The aortic valve normal function, but the pulmonic valve was stenotic and had abnormal function.

• Journal of Chest Surgery
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• v.20 no.1
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• pp.55-69
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• 1987

The result of valve failure with the lonescu-Shiley pericardial xenograft was presented with the review of current knowledge. This study reviewed 557 patients, who underwent total of 683 lonescu-Shiley pericardial valve replacement from 1979 to 1985 at Seoul National University Hospital. There were 357 patients who had mitral valve replacement, 73 with aortic valve and 127 with double valve replacement. There were 35 operative deaths. The survivors were followed at OPD. There were 32 patients who had prosthetic valve failure, whose ages ranged from 11 to 58 years [mean 27.8] and their postop interval was 56 ~ 22 months [range; 6-87] The causes of valve failure are prosthetic valve endocarditis in 14, primary disruption or calcification in 13, paravalvular leakage in 4, and others in 2 patients. Redo valve replacement was done in 12 patients after a mean interval of 50 * 20 months. [range; 6-79 months] Actuarial analysis of late results indicates actuarial freedom from endocarditis at 6 year is 87.9 ~ 6.8%, and actuarial freedom from primary disruption or calcification or paravalvular leakage at 5 year is 84.4 * 2.3%. In this series, however, valve failure due to thrombosis is not included.

• Journal of Chest Surgery
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• v.33 no.1
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• pp.45-50
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• 2000

Background: The CarboMedics prosthetic heart valve was produced in an attempt to improve the existing valve designs and was especially concerned with easily the implantation and further reduction of turbulence. Precise positioning of the valve in situ was achieved by the abilityof the valve to rotate relative to the sewing ring. Improved monitoring is possible due to increased radiopacity and the dacron sewing ring is coated with carbon to reduce pannus overgrowth. The leaflets have an opening angle of 78 degrees that apparently allows a rapid synchronous closure The aim of this study was to analyze the clinical performance of the CarboMedics valve prostheses(45 mitral 13 aortic and 7 double aortic-mitral valve replacement) were implanted in 65 patients(mean age 48.75$\pm$9.74 years) Result: The operative mortality was 3.1%(2/65) causes of death were low cardiac output syndrome. Total follow up was 1831 patient-months and mean follow up was 29.06$\pm$10.97 months/patient. No structural failure hemorrhage valve thrombosis and late death have been observed. Embolism occurred at a rate of 0.65%/Patient-year. Actuarial survival and thrombo-mbolism free rate at 36 months were 96.9% and 98.4% respectively. Consclusions: The CarboMedics valve stands for low valve related complicatons.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.4
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• pp.370-377
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• 2018

Ball valve has been widely used in the field of high-pressure gas pipeline as an important component because of its low flow resistance and good leakage performance. The present paper focuses on the flow nature at the downstream of the ball valve used for gas pipelines according to valve opening rates. Steady 3-D RANS equations, SC/Tetra, have been introduced to analyze the flow characteristics inside the ball valve. Numerical boundary conditions at the inlet and outlet of the valve system are imposed by mass flow-rate and pressure, respectively. Velocity distributions obtained by numerical simulation are compared with respect to the valve opening rates of 30, 50, and 70%. Cavity distributions, asymmetry flow velocity and the flow stabilization point at each opening rate are also compared. When the valve opening rates are 30 and 50%, the flow stabilization requires the sufficient length of 10D or more due to the influence of the recirculation flow at the downstream of the valve.

• Fire Science and Engineering
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• v.21 no.3
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• pp.91-96
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• 2007

Performance analysis of the butterfly valve in water fire extinguishing has been carried out. Performance analysis of the butterfly valve are investigated for torque characteristics, pressure loss and cavitations. The torque characteristics of disc are corrected for the angles of attack of valve disc by theoretical torque equation, and correction equation is added. The pressure loss coefficient on opening angle of valve has been formulated by applying the Carnot's equations. The torque characteristics, pressure loss and cavitations of the butterfly valve are analyzed for the ratio of disc thickness to the valve diameter. Cavitations are analyzed from the pressure loss coefficient of valve. The analysis of pressure loss and cavitation has been carried out change of the thickness ratio on opening angle of valve. These analysis data are utilize to necessary engineering data to develope of the butterfly valve.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.1
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• pp.81-88
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• 2011

The triple eccentric butterfly valve has metal sheet and this study about butterfly valve ceiling is an innovative approach. But it is affected by the static pressure as well as cross-current. The damage at the valve on the pipe resulted from the reflux is due to valve leakage. This study is investigated on the triple eccentric disk and it is applied with angle and the static pressure in all cases to develop cross-current triple eccentric butterfly valves. The disc with the diameter of 300A is valve against flow velocity. The entrance pressure by flow characteristics is performed with numerical analysis. As the result, valve torque production is reduced more than the conventional triple eccentric valve and entrance pressure is decreased on the increase of valve open angle. And flow coefficient can be known to be increased.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.8
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• pp.1083-1090
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• 1998

A kind of three-way check valve, so called hydraulic calve was proposed for the substitute of the density lock of passive reactor such as SPWR (System-Integrated Pressurized Water Reactor). The function of the valve are the separation of the borated water from main coolant loop for normal operation and the insurge of the water into the loop for shutdown and the removal of the decay power when the main coolant flow rate is not enough. To verify the operability and the characteristics of the valve, experimental works were executed with 1/3 scale model calve. Also a diffuser model was proposed for the theoretical analysis of the valve.

• Journal of Chest Surgery
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• v.28 no.6
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• pp.579-582
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• 1995

The extended transseptal approach to the mitral valve replacement has been used for 30 patients. There were 19 women and 11 men. Twenty five patients had rheumatic heart disease, 4 had degenerative valve ,and 1 had valve prolapse. Fifteen of 30 patients had other associated procedure; 10 had aortic valve replacement; 5 had tricuspid annuloplasty. There were no postoperative complications associated with the approaches, ie, no bleeding, no sinus node dysfuction, and no atrioventricular conduction disturbance. Despite division of the sinus node artery, preoperative atrial rhythms[3 sinus rhythms and 27 atrial fibrillations were not changed during postoperative period. The extended transseptal approach provides good mitral valve exposure without inherent complications, and is superior to that of standard approach, so we use it routinely for mitral valve procedure.

• Journal of Industrial Technology
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• v.19
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• pp.51-57
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• 1999

This research has an object to find out how the position of inlet valve influence swirling and tumbling of turbulence inside the combustion chamber of 4 valve engine. The computational analysis of three dimensional complicated turbulence flow in the cylinder is done by the KIVA-3V program to carry out this object. One use 6 valve positions with the bowl type of piston cavity. The swirl ration and the tumbling ratio of flow filed are evaluated quantitatively to find out how each valve position influence flow phenomena in the combustion chamber during the intake and compression processes.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.1
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• pp.110-122
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• 1996

The objective of this study is to understand the dynamic characterictics of OHV type valve trains and to design and optimal cam profile which will improve engine performance. A numerical model for valve train dynamics is presented, which aims at both accuracy and computational efficiency. The lumped mass model and distributed parameter model were used to describe the valve train dynamics. Nonlinear characterictics in the valve spring behavior were included in the model. Comprehensive experiments were carried out concerning the valve train dynamics, and the model was tuned based on the test results. The dynamic model was used in designing an optimal cam profile. Because the objective function has many local minima, a conventional local optimizer cannot be used to find an optimal solution. A modified adaptive random search method is successfully employed to solve the problem. Cam lobe area could be increased up to 7.3% without any penalties in kinematic and dynamic behaviors of the valve train.