• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.75-80
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• 2014

In previous study, make an attempt to estimate exhaust valve seat and seat-ring wear acceleration factor for engine durability test with measuring and consideration of wear mechanism. But found abnormal initial wear rate in exhaust valve seat-ring. And have to improve exhaust valve seat-ring wear rate for reliability reason, because next GDI/Turbo engine is based on this engine and GDI/Turbo engine have higher combustion pressure and higher thermal load. In this study, Trying to find the cause of abnormal wear factor, improve valve-train durability by change specification & design of parts and verify variant parts for improving durability of valve-train. And then I would like to propose a design guide line of valve-train system in a reliability point of view, besides make a complement of previous study.

• Journal of Chest Surgery
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• v.16 no.4
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• pp.458-469
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• 1983

Between October, 1978, and December, 1982, Glutaraldehyde-stablized pericardial xenografts [Ionescu-Shiley valve] were used for heart valve replacement in 409 patients.[251 mitral, 49 aortic, 11 tricuspid, and 98 multiple valve replacement]. There were 31 early deaths [7.6%], and 371 operative survival were observed for a total of 507.6 years over a period of 1 to 44 months. [mean 17 months]. Actuarial analysis of late results indicates an excepted survival rate at 4 years of 86.25.4% for patients with mitral, 79.37.1% for patients with aortic valve replacement. Actuarial survival rates for total patients at 4 years was 77.88.2%. The rate of systemic embolism has been 1.6% per patient-year for mitral and 1.8% per patient-year for aortic group in the presence of anticoagulation treatment. Among the 6 embolic episodes, 2 patients were died. The incidence of hemorrhagic complication was 1.3% per patient-year for anticoagulated patients. There were 6 confirmed valve failures, five in mitral and one in aortic position. Re-replacement of destructed valve was performed in one patient and others were treated medically. Among the 6 episodes, 3 occurred in children [Below 15 years], it account almost 9 times higher than adult. Our clinical data compare very favorable with those obtained with other available prostheses and tissue valves, but it should be considered to give short-term anticoagulation therapy to hemodynamically stable patients and aortic valve patients, and other prosthetic valve must be considered to use in children.

• Journal of Mechanical Science and Technology
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• v.19 no.8
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• pp.1621-1631
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• 2005

In this paper, making the best use of the features of the electro-rheological (ER) valve, a two-port pressure control valve using ER fluids is proposed and manufactured. The ER-Valve characteristics are evaluated by changing the intensity of the electric field and the number of electrode. As only with electrical signal change to the ER-Valve in which ER fluid flowing, ER fluid flow is controlled, so development of simple ER-Valves have been tried. The ER-Valves and pressure drop check method are considered to be applied to the fluid power industry. Using the manufactured pressure control valve, a one-link manipulator with FHA (Flexible Hydraulic Actuator) is driven. As a result, it is experimentally confirmed that the pressure control valve using ER fluids is applicable to use in driving actuator. If it applies characteristics of the ER fluids, it will be able to apply in the control system for the ER Valve which occurs from industrial controller. After having durability test, shear stress increased regularly because of starch particles crushed by pump and particle size that was almost the same. Moreover, Ra of copper electrode increased about 1.56 times rather than before those of performing durability test, and Rz increased about 2.2 times.

• Journal of ILASS-Korea
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• v.23 no.2
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• pp.58-65
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• 2018

An analytic strategy to control the variable valve actuation applied to two intake valves (flow port intake valve and swirl port intake valve) was performed in this study. we considered the variation in phasing of intake valve profiles by using the Cam-in-Cam technology. The analytic model was implemented in the GT-Power simulation program and analyzed the result of regulated emissions such as, NOx and Soot, especially with IMEP characteristics. Namely, we meticulously investigated the sources of having effect on the amount of NOx and soot formation under the test conditions with retard timing of both flow port and swirl port intake valves for decreasing the opening duration by 35CAD. Also, we analyzed the effect of incylinder pressure and temperature with NOx variations and in-cylinder pressure and temperature on NOx variations and normalized turbulent intensity. Through this analysis, some useful results on the combustion and flow characteristics of the swirl port and flow port control of the intake valve were obtained by this study.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.31-37
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• 2016

In the steam system, a stream trap valve discharges a condensate and a non-condensable gas. It also prevents stream from being leaked. The free float stream trap valve is a mechanical type of stream trap. The valve is opened when a hallow ball is floated due to the density of the condensate through the condensate flows into the valve. On the other hand, when the flow of the condensate is completed, the valve is closed as the float subsides due to the weight of the structure and the stream is blocked. In addition, the bimetal lifts the hallow ball, which discharges the non-condensable gas. In this study, the performance of the properties of the free float stream trap valve, the method of support for three points, and the orifice design are researched. Moreover, the condensate discharge capacity of the free float stream trap valve is calculated from the experiment.

• Journal of Chest Surgery
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• v.20 no.3
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• pp.557-564
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• 1987

From September 1980 to July 1986, 135 cases of cardiac valve surgery were performed under the cardiopulmonary bypass. Out of 135 cases, single valve surgery was 114 cases including open mitral commissurotomy 17, mitral annuloplasty 2, mitral valve replacement 85, and aortic valve replacement 10 and double valve surgery was 21 cases. There were 68 males and 67 females ranging from 9 to 57 years of age. Early death within 30 days after operation was 17 cases [12.6%] and caused of death were ventricular arrhythmia 5, low cardiac output syndrome 4, excessive bleeding 3, pulmonary complication 2, and so on. Among 118 early survivors, 5 cases [5.1%] of late death were developed over a period of 2 to 72 months, and main cause of death was fatal bleeding complication associated with anticoagulation therapy. Symptomatically, 91.8% of patients were in NYHA functional class I or II at the end of the follow-up.

• Journal of Chest Surgery
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• v.22 no.6
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• pp.970-979
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• 1989

From April 1982 to December, 1988, multiple valve replacement was performed in 49 patients. Mitral and aortic valve replacement were done in 42 patients, 4 underwent mitral and tricuspid valve replacement and 3 patients underwent triple valve replacement. Of the valve implanted, 50 were Duromedics, 21 St. Jude, 13 Bjork-Shiley, 9 Carpentier-Edwards, 6 Ionescu-Shiley, and 2 Medtronic. The hospital mortality rate was 28.5 % [14 patients] and the late mortality rate was 6.1 % [3 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] The causes of death were low cardiac output in 8, congestive heart failure in 2, multiple organ failure in 1, LV rupture in 1, intracerebral hemorrhage in 1 and sudden death in l. The actuarial survival rate excluding operative death was 77% at 7 years.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.2
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• pp.41-46
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• 2007

Butterfly valves are commonly used as control valves in applications where the pressure drops required of the valves relatively low. As the shutoff valve (on/off service) or throttling valves (for flow or pressure control), the higher order and the better precision of butterfly valves are required. The it's more and more essential to know the flow characteristic around the valve. Due to the fast progress of the flow visualization and numerical technique, it becomes possible to observe the flows around a valve and to estimate the performance of a valve. Researching these results did not gave only access to understand the process of the valve flows at different valve opening angles, but also was made to determine the accuracy of the employed method. Furthermore, the results of the three-dimensional analysis can be used in the design of butterfly valve in the industry.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.184-193
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• 2006

Rotation of intake and exhaust valves are very closely related to the long term durability of automotive engines. If the valves do not rotate even at a rated engine speed, it causes the uneven wear of the valve seat and valve head contact area, which eventually shortens the engine life. A principle of valve rotation mechanism was presumed based on some findings from experiments, and computer programs were developed to simulate the valve rotation phenomena. In this study we investigated the valve rotation mechanism by using the computer simulation models.

• The KSFM Journal of Fluid Machinery
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• v.2 no.1 s.2
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• pp.108-113
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• 1999

In a scroll compressor it is generally accepted that a check valve is necessary to prevent reverse rotation of the scrolls. The check valve is subjected to discharge pulsations and their resultant forces. The flow phenomena around the check valve may affect the efficiency and the noise level significantly. The motivation of this study is to understand the flow phenomena and the unstable motion of the check valve on operating conditions in order to identify reasons raising noise and improve the performance of the check valve. In this study, unsteady flow simulation was performed using CFD and the pressure distribution around the check valve was obtained. This paper also shows that unstable motion of the check valve on standard operating conditions through theoretical analysis and flow visualization.