• Journal of Drive and Control
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• v.18 no.4
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• pp.1-8
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• 2021

An electro proportional pressure control valve is mainly used to control the clutch of an agricultural tractor's automatic transmission. During transmission, the operating, hydraulic oil is mix with many kinds of contaminants. The contaminants can be trapped between the valve body and spool of the proportional pressure control valve leading to abnormal operating conditions and finally critical damage to the transmission hydraulic system. The present study aimed to verify the valve control algorithm as a basic study of developing control logic that removes contaminants between the spool and the body of the proportional pressure control valve. To develop the algorithm, MATLAB/SIMULINK was used. PWM method was used to control the applied solenoid coil current. The effectiveness of the algorithm was verified by comparing the actual pressure of the normal valve with the actual pressure of the abnormal valve. Based on the present study findings, when the algorithm was applied, the response of the valve pressure according to the current became stable and oil contaminated particles were removed. In the future study, the control algorithm will be optimized for the stability of the proportional pressure reducing valve, and it will be verified in consideration with the driving of the clutch.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.2
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• pp.138-142
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• 2013

As an early warning system to reduce the damage of aquacultured mollusks due to low salinity water, we investigated the possibility of a biomonitoring system measuring the shell valve movement (SVM) of Pacific oyster (Crassostrea gigas) by using the Hall element sensor. In high salinity water of 27 psu, SVMs of Pacific oyster showed spikes which mean a relatively fast closing condition after opened condition of average 10-15 mm, and then the SVM showed back to opening condition slower than closing speed. In water salinity of 20-27 psu, the SVMs were similar to that of 27 psu. However, below 17 psu, it showed abnormal valve movements such as spending more time for shell closure. In 10 psu, we could not detected SVMs due to closed condition during experiment periods. Thus, if we quickly detect abnormal environmental variations like low salinity using bio-monitoring of SVM, it may be contribute to increased productivity by dramatically reducing damages in aquaculture.

• Journal of Hydrogen and New Energy
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• v.19 no.3
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• pp.182-188
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• 2008

In order to improve scavenging performance of free piston hydrogen fueled engine, this study estimate compatibility of uni-flow scavenging. The scavenging flow characteristics in the cylinder is investigated by flow visualization and PIV method. Consequently it has been found that the scavenging performance decreased with abnormal expansion of piston and delay of the exhaust valve opening timing. And the scavenging performance of exhaust valve located center in cylinder head is better than that of exhaust valve located side in cylinder head.

• Journal of Chest Surgery
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• v.27 no.4
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• pp.313-317
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• 1994

Surgical treatment is possible for the obstructive form of hypertrophic cardiomyopathy and transaortic left ventricular septal myectomy and myotomy has been the procedure of choice. If coexisting intrinsic mitral valve disease exists, mitral valve replacement has been performed. But abnormal systolic anterior motion of anterior mitral leaflet[SAM] with intrinsic normal mitral valve disease is the typical feature of IHSS and we prefer not to replace mitral valve. 3 patients underwent transaortic myotomy and myectomy for IHSS with mitral regurgitation. 2 patients of them have coexisting intrinsic mitral valve diseases such as mitral valve vegetation and chorda rupture. Concomittent mitral valve replacement were performed. 1 patient shows SAM of mitral anterior leaflet but has intrinsic normal mitral valve morphologically and transepicardial echocardiogram and direct monitoring of pressure gradient during the operative procedure gives better information for subsided mitral regurgitation. Post operative course during the 12 months follow-up was uneventful.

• Journal of Power System Engineering
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• v.11 no.1
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• pp.45-50
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• 2007

Acoustic emission technology is applied to diagnosis the internal leak and operating conditions of the major valves at nuclear power plants. The purpose of this study is to verify availability of the acoustic emission as in-situ diagnosis method. In this study, acoustic emission tests are performed when the pressurized high temperature steam flowed through gate valve(1st stage reheater valve) and glove valve(main steam dump valve) on the normal size of 4 and 8". The valve internal leak diagnosis system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, signal level analysis and RMS(root mean square) analysis of acoustic signal emitted from the valve operating condition internal leak.

• Journal of Chest Surgery
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• v.10 no.1
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• pp.156-163
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• 1977

This is a report of a case in which mitral valve replacement was performed using Starr-Edwards ball valve [model 6230] by total cardiopulmonary bypass with total hemodilution prime and moderate hypothermia. The patient was 21 year old girl, and mitral valvular symptoms occurred 5 years ago. According to clinical features of the disease, the patient was classified as the class IV of N.Y.H. A. cla3sification. The preoperative diagnosis of mitral insufficiency was made mainly by left ventriculography of roentgenologic study. The mitral valve was highly deformed due to scar contraction of valve leaflets and shortening of chordae tendineae. After prosthetic valve replacement, no abnormal hemodynamic signs were observed. The postoperative course was uneventful.

• Journal of Power System Engineering
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• v.11 no.1
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• pp.39-44
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• 2007

The purpose of this study is to verify availability of the acoustic emission in-situ monitoring method to the internal leak and operating conditions of the major valves at nuclear power plants. In this study, acoustic emission tests are performed when the pressurized temperature water and steam flowed through glove valve(main steam dump valve) and check valve(main steam outlet pump check valve) on the normal size of 12 and 18". The valve internal leak monitoring system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, frequency analysis, voltage analysis and amplitude analysis of acoustic signal emitted from the valve operating condition internal leak.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.666-671
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• 2007

To acquire the safety along with durability of mechanical machinery products, we should consider the structural mechanics such as stress, deformation and dynamic vibration characteristics and identify those important aspects in the stage of preliminary design engineering. This cryogenic ball valve is used to transfer the liquified natural gas which temperature is $-196^{\circ}C$, supplied pressure is $168kg/cm^2$. For the cryogenic ball valve, the assurance of structural integrity and operability are essential to meet not only normal, abnormal loading conditions but also functionality during a seismic event. In this thesis, analytical approach and results using finite element analysis and computational method are herein presented to evaluate the aspects of structural integrity along with operability of cryogenic ball valve. In this study, we designed the high pressure cryogenic ball valve that accomplishes zero leakage by elastic seal at normal temperature and metal seal at high temperature.

• Journal of Power System Engineering
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• v.12 no.5
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• pp.65-70
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• 2008

The purpose of this study is to verify availability of the acoustic emission in-situ monitoring method to the internal leak and operating conditions of the turbine major valves relating to safety for turbine operating and prevention of turbine trouble at nuclear power plants. In this study, acoustic emission tests are performed when the pressurized electro-hydraulic control oil flowed through turbine electro-hydraulic controller oil check valve and turbine power/trip fluid solenoid valve in the condition of actual turbine operating. The acoustic emission method was applied to the valves at the site, and the background noise was measured far the abnormal plant condition. To judge for the leak existence ell the object valves, voltage analysis and frequency analysis of acoustic signal emitted from infernal leak in the valve operating condition are performed. It was conformed that acoustic emission method could monitor for valve internal leak to high sensitivity.

• 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.