• Computers and Concrete
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• v.24 no.5
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• pp.437-444
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• 2019

PLC and its expansion module, electric ball valve and cooling pipe, electric heating steel plate and various components of the system, which is used to control test and process data. By automatically adjusting the opening of the valve, the system makes the top temperature and cooling speed develop along the ideal temperature diachronic curve. Moreover, the system enables the temperature difference between inside and surface of test block limited in a given range by automatically controlling the surface board heating. The method of physical simulation test by sandbox with built-in cooling water pipe and heating rod is adopted. On the premise of a given standard value, the operation of the system is checked under different working conditions. Further, an extension of this system is proposed, which enables its application to obtain some thermal parameters when cooperating with numerical simulation.

• Journal of the Korean Institute of Gas
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• v.20 no.5
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• pp.57-63
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• 2016

Though a valve is a very important part in a system to control properly, it has potential failure caused by gap from valve stem to ball connection, and abrasion, crack, fixation causing operational trouble and accidents. 64% of the valve failure in the real case was the failure of airtightness and most accidents of leakage and explosion were occurred while fixing the failure. While there are no proper safety manual, maintenance procedure and regulation for industrial valves excluding safety valve, safety management for the valves is left to the discretion of the maintenance company. Strict maintenance that removes hazards and emergency response procedure are required to prevent and reduce the loss of accident. This study suggests safety enhancement measures through valve monitoring by investigating the status of use of valve and current maintenance. Enhancement of gas safety management can be acquired by a monitoring system that provides diagnosis for valve status, monitoring real-time gas leakage, management of entire cycle lifetime that can reduce maintenance cost.

• Journal of the Korean Institute of Gas
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• v.19 no.5
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• pp.1-6
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• 2015

In this paper, the strength safety of a fuse cock main body has been analyzed by the finite element method. The stress and displacement behaviour characteristics have been investigated for thickness variations at the region of (T) between a ball valve and a fuse cock safety connector. The FEM analyzed results recommend that the optimized thickness at the region of (T) is from 1.55mm to 1.6mm for the supplied gas pressure of 1.5~3.5MPa. This is considered for the optimized strength safety and light weight of a fuse cock main body.

• Journal of Ocean Engineering and Technology
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• v.28 no.2
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• pp.160-166
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• 2014

Because of industrial development, industrial facilities are becoming more complex and diversified. Plant industries are focused on productivity improvement, cost reduction, and product uniformity by simplifying production processes using automated control. Furthermore, plant industries require higher pressures and temperatures to improve energy efficiency. For this reason, the valves used in plants are operated under harsh conditions. Globe valves and gate valves are mainly used for high pressure these days. However, these valves have various problems, including low maintainability and high cost, due to structural problems. Therefore, butterfly and ball valve applications are increasing in industrial plants. This paper suggests a quadruple-offset butterfly valve that is applicable to bi-direction use, and the principle design parameters are suggested. The selected design parameters are an eccentric flange center line and shaft centerline(Offset 1), an eccentric seat centerline and disc shaft centerline(Offset 2), the angle between the flange centerline and seat wedge angle(Offset 3), the angle between the vertical direction of the disc shaft centerline and seat centerline(Offset 4), and the seat engagement angle. To analyze the interaction effect of the design parameters, ANOM and ANOVA were performed with an orthogonal array. The parameters were found to have effects in the following order: Offset 2, Offset 1, engagement angle, Offset 3, and Offset 4. The interaction between the parameters was insignificant.

• Tribology and Lubricants
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• v.37 no.6
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• pp.246-252
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• 2021

Among the engine components of an internal combustion engine, the valve train is a series of systems that supply intake gas to the combustion chamber and operate intake and exhaust valves that discharge exhaust gas. If excessive wear occurs in the valve train system, the suction and exhaust valves do not open and close on time, which leads to abnormal combustion and exhaust gas. In this study, we conduct experiments and analyses on friction and wear characteristics of the valve train system. Moreover, we experimentally study the correlation between the pinball and pinball cap on engine oil lubrication, friction experiment, wear amount analysis, and surface analysis. Specifically, we experiment using Ball on reciprocating tribo-tester and apply commercial engine oil sold on the market engine oil. We construct the experimental conditions for each new oil and oil. Accordingly, the completed specimen was subjected to a confocal microscope to check the wear volume, observe the surface of the specimen, and confirm the elemental components using a scanning microscope (SEM) and an energy dispersion X-ray spectrometer (EDS). Through this experiment, we analyze the friction and wear characteristics of valve train components according to engine oil grade, and the obtained data serve as an effective engine oil management method.

• 한국가스학회:학술대회논문집
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• 2006.11a
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• pp.245-250
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• 2006

• Journal of Chest Surgery
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• v.29 no.6
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• pp.655-659
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• 1996

Primary cardiac tumors are known to be rare. Of the benign primary tumors, rhabdomyoma predominates in neonates and infants. Tuberous sclerosis is found in hall of the patients with rhabdomyomas. Rhabdomyomas demonstrate benign pathological characteristics and may regress spontaneously that resection of the intracavitary obstructing portion of these tumors are recommended. We performed resection of intraatrial rhabdomyoma which had been obstructing mitral valve orifice and caused heart failure in a neonate. Postoperatively, fungal endocarditis developed and after 3 days, rapid growth and extension of the vegetation in the aorta obstructed the flow through the ascending aorta and resulted in hemodynamic deterioration.

• Journal of Aerospace System Engineering
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• v.12 no.5
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• pp.32-39
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• 2018

In this paper, the calculation of the theoretical pressure transfer ratio due to the deformation of the thin-plate spring type check valve applied to the small piezoelectric-hydraulic pump was carried out. A thin-plate check valve is a flexible body that is deformed by an external force. The deformation of the check valve affects the rate at which the chamber pressure is transferred to the load pressure. The theoretical pressure transfer ratio for each model was calculated to compare the difference between the assumption that the thin-plate check valve is a rigid body and that of the flexible body model. The P-delta effect was considered for the calculation of the pressure transfer ratio of the flexible check valve model. In addition, a verification test for the calculated pressure transfer ratio obtained by considering the deformation of the flexible check valve model was carried out. The load pressure was measured by applying a thin-plate and ball-thin plate spring type check valves, respectively. The experimental pressure transfer ratio was calculated using the respective load pressure obtained from the experiments. The validity of the pressure transfer analysis of the check valve, taking into consideration the P-delta effect, was verified by comparing it with the theoretically calculated pressure transfer ratio.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.6
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• pp.34-41
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• 2014

A feasibility study of thrust control of hybrid propulsion system for lunar exploration is presented. The thrust control experiments were performed by controlling the oxidizer mass flow rate where the thrust modulation is carried by using a ball valve and a stepping motor. The gaseous oxygen (GOX) and the HDPE (High Density PolyEthylene) were used for the oxidizer and solid fuel, respectively. It was found that the thrust levels were stable without much fluctuation during the modulation period, and that the thrust was exactly controlled with target thrust modulation ratio of 53% and 32%.

• Journal of Yeungnam Medical Science
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• v.10 no.1
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• pp.237-244
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• 1993

A free-floating ball thrombus in the left atrium is a rare complication of the mitral valvular disease. A 53-year-old man was admitted for pain and paresthesia on both legs. On admission he had auscultatory sign of mitral stenosis and mitral regurgitation, and the roentgenogram of his chest revealed a slight pulmonary venous congestion, enlargement of the pulmonary conus and cardiomegaly. Laboratory findings including complete blood counts, coagulation studies and blood chemistry were normal. An echocardiographic examination revealed a mitral stenosis and a free-floating ball thrombus in the left atrium. We performed the emergent open heart surgery for removal of the ball thrombus and mitral replacement successfully with Duromedics 29 mm valve. The size of thrombus was $39{\times}32{\times}30$ mm.