• 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.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.3
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• pp.868-876
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• 1995

This study deals with a position control of an electro-hydraulic servo system which consist of cylinder and high speed on-off valves operated by microcomputer. The merits of PWM control of hydraulic equipment are the robustness of the high spee on-off valve, its low price and the direct control without D/A converter. In the PWM control of high speed on-off valve, the time lag and switching time existing between the input and output signals of valve are considered as demerit points. To get analytical results, the effects of these demerits have to be clarified in detail. The object of this study is to propose a mathematical model for the behavior of high speed on-off valve and to get analytical results of this system. The dynamic characteristics of this system is examined by digital computer simulation analytically and compared with experimental results to varify the proposed mathematical model.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.5
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• pp.41-47
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• 2007

The structure of ER valve is simple that its designing and manufacturing are easy. The flow rate and pressure of ER fluids flowing in the ER valve are controlled only by electric field. In this study a three port ER valve is designed and manufactured. Then, the flow rate and pressure dorp of ER fluids flowing in the ER valve are measured. The system proposed controls flow rate and pressure fast. So, this system can be easily substituted for the existing hydaulic and pneumaitc control system.

• 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 Chest Surgery
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• v.44 no.3
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• pp.240-242
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• 2011

We experienced a case of ruptured aneurysm of the sinus of Valsalva, and this resulted in simultaneous aortic and tricuspid valve endocarditis through a shunt. The echocardiography showed a ruptured sinus of Valsalva aneurysm to the right atrium with a shunt. The aortic non-coronary cusp was fibro-thickened with vegetation. Vegetations of the septal leaflet and the anterior leaflet of the tricuspid valve were also found. The blood culture grew Enterococcus garllinarum. We replaced both tricuspid and aortic valve with successful surgical result.

• Journal of Chest Surgery
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• v.29 no.2
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• pp.164-170
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• 1996

From January 1986 to June 1993, 12 patients Aad required reoperation: 9 had undergone mitral and 3 aortic valve replacement. Five were male and 7 female, and ages ranged from 29 to 61 years. Replacement of the prosthetic heart valve was performed at a mean interval of 98 $\pm$ 1 months after the Hrst operation. In aortic valve replacement patients the mean interval was 115 $\pm$ 2 months and in mitral valve replacement patients 98 $\pm$ 4 months. Primary tissue failure was the most frequent reason of replacement (10 patients) followed by valve thrombosis (1 patient) and prophylactic replacement (1 patient) in order. The most pronounced pathology of the failed prosthetic heart valves seen in the primary tissue failure group was calcification, perforation, shrinkage and tearing of the cusps. There was one early operative death (8.3%) due to intractable low cardiac output and acute renal failure. Eleven early survivors had successful operative results and there was no late death.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.3
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• pp.75-84
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• 1994

In general direct-operated pressure reducing valves have been gardly applied to a dynamic control system such as active suspension control because of their poor control stability. But they are more robust than pilot-operated type and do not need pilot control flow. In this paper development of a new direct-operated proportional pressure reducing valve for low-band type active suspension control is reported. By means of a special damper directly linked to the valve spool, the control stability could be effectively improved without drawback in response time. The linearity error was less than $\pm$3.5%. Applied to an experimental active suspension system the new valve showed the $-90^{\circ}$ phase delay at 4Hz with 20% sinusoidal signal input and could control the suspension system with almost same performance as that with a pilot-operated type valve.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.389-394
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• 2017

The limitation of flow control for a bistable fluidic valve has been investigated. The physical model of the fluidic valve includes two main flow outlets and two control flow inlets. The experiments were conducted with pressure regulators, mass flow meters, and piezo sensors to analyze flow switching characteristics of the fluidic valve. The experimental data such as pressure and mass flow rate of control flows and the switching time of the main flow was obtained with various operating conditions. The operation limit of the fluidic valve is identified, and a model equation for pre-estimating the minimum control pressure to switch the direction of the main flow has been proposed.

• Journal of Veterinary Clinics
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• v.24 no.3
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• pp.444-448
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• 2007

An intact female, 2 month old, domestic short hair cat, weighing 0.82kg with a history of respiratory distress, anorexia, and depression for 3 days was referred. In laboratory examination, there were no remarkable abnormalities. Radiographic findings mainly included pleural effusion, dilation of pulmonary vessels, pulmonary edema, and ascites. Echocardiography showed dilation of four cardiac chambers, malformation of the tricuspid and mitral valve, and atrioventricular valve regurgitant jet flow. The cat was euthanized by client's request and confirmed to the tricuspid and mitral valve dysplasia by necropsy and histopathologic examination.

• Journal of Drive and Control
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• v.11 no.3
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• pp.41-46
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• 2014

The neutral valve for controlling the HST is one of the important valves for the vehicle control. Neutral valve takes a role of blocking or transmitting power to the vehicle. The operating principle of the neutral valve was developed through the analysis model. We also investigated the logical validity by analyzing the results of the analysis model. The analysis model was developed by using SimulationX witch is commercial software. The number of holes in the piston was selected as a variable initial compression of the spring, and the magnitude of the pressure pulsations and the diameter of the orifice for the sensitivity analysis were performed to design sensitivity analysis of the neutral valve.