• The KSFM Journal of Fluid Machinery
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• v.9 no.5 s.38
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• pp.14-21
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• 2006

In general, the hollow jet valve, the fixed cone valve had been used for the urgency released or maintenance of the flow rate. Nowadays, the butterfly valve, the gate valve are applied in economic performance and operation maintenance more than the hollow jet valve, the fixed cone valve. However, in the case of butterfly valve, it should be required the strict application standard to the cavitation coefficient because the structural axis and disk were situated in pipe channel and the occurring the shock problem by Karman Vortex. Therefore, there were investigated the valve cavitation and accident investigation by field survey to establish the applicable extensibility of the urgency released valve as the preliminary study.

• Journal of the Korean Institute of Gas
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• v.21 no.3
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• pp.1-8
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• 2017

The purpose of this study is to suggest the rupture disk design(size) and application at the two phase(gas-liquid) flow by runaway reaction at batch reactor. The definition of runaway reaction is abnormally exothermic reaction by the uncontrolled cooling water or deviated operating condition. As a result, the temperature of reactor is rapidly increasing. The causes of runaway reaction are either self-heating reaction or sleeper reaction. General methods of rupture disk size or safety valve are not suitable in the runaway reaction, because of temperature and pressure increasing rapidly in the reactor and the phases of relieving fluid is 2-phase flow. This study case of the reactor incident, the depressurization system such as safety valve and vent installed, however, the system did not relieved the pressure of reactor suitably. The orifice size of the safety valve were designed too small because the size had not been considered the phenomena and character of reaction. The batch reactor design should be considered by referring to the possibility of runaway reaction proposed in this study and the size of rupture disk design method considering 2-phase flow.

• Journal of Mechanical Science and Technology
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• v.19 no.12
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• pp.2245-2252
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• 2005

Thermal stratification in the branch piping of power plants can be generated by turbulent penetration or by valve leakage. In this study, a numerical analysis was performed to estimate the thermal stratification phenomenon by in-leakage in the SIS branch piping of nuclear power plant. Leakage rate, leakage area and leakage location were selected as evaluation factors to investigate the thermal stratification effect. As a result of the thermal stratification effect according to leakage rate, the maximum temperature difference between top and bottom of the horizontal piping was evaluated to be about 185K when the valve leakage rate was about 10 times as much as the allowed leakage rate. For leakage rate more than 10 times the allowed leakage rate, the temperature difference was rapidly decreased due to the increased mixing effect. In the result according to leakage area, the magnitude of temperature difference was shown in order of $3\%,\;1\%\;and\;5\%$ leakage area of the total disk area. In the thermal stratification effect, according to the leakage location, temperature difference when leakage occurred in the lower disk was considerably higher than that of when leakage occurred in the upper disk.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.20 no.2
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• pp.35-39
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• 2014

One-way degassing valves are designed to allow pressure to be released from an air-tight package while preventing air from getting back into the package. Air, especially the oxygen ($O_2$) portion of air, can have negative effects on the package contents and its freshness. The most common application of the one-way degassing valve is for fresh roasted coffee. Demands of one-way degassing valves have been increasing with the high growth of global coffee market. In this study, we have developed one-way degassing valves for coffee and food packaging using ring type rubber disk, named SP valve. Its quality and performance was verified with test results to be equal with that of global top maker's product, Goglio valve. SP valves showed 820~1200 Pa of opening pressure, 10~50 Pa of closing pressure, 1.2~1.6 L/ min of flow rate. And, the SP valve applicable to ferment food packaging is expected to contribute to globalize Korean traditional food.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1382-1399
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• 2023

Pressure relief valve (PRV) is one of the important control valves used in nuclear power plants, and its sealing performance is crucial to ensure the safety and function of the entire pressure system. For the sealing performance improving purpose, an explicit function that accounts for all design parameters and can accurately describe the relationship between the multi-design parameters and the seal performance is essential, which is also the challenge of the valve seal design and/or optimization work. On this basis, a surrogate model-based design optimization is carried out in this paper. To obtain the basic data required by the surrogate model, both the Finite Element Model (FEM) and the Computational Fluid Dynamics (CFD) based numerical models were successively established, and thereby both the contact stresses of valve static sealing and dynamic impact (between valve disk and nozzle) could be predicted. With these basic data, the polynomial chaos expansion (PCE) surrogate model which can not only be used for inputs-outputs relationship construction, but also produce the sensitivity of different design parameters were developed. Based on the PCE surrogate model, a new design scheme was obtained after optimization, in which the valve sealing stress is increased by 24.42% while keeping the maximum impact stress lower than 90% of the material allowable stress. The result confirms the ability and feasibility of the method proposed in this paper, and should also be suitable for performance design optimizations of control valves with similar structures.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.4
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• pp.801-805
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• 2009

This paper reports on a flexible flap valve actuated by electromagnetic force under a constant pressure source. The flexible flap valve consists of the three main components: a flexible flap with a steel disk embedded in PDMS, an electromagnetic actuator and two glass plates with inlet and outlet. The flap valve is fabricated by SU-8 mold process, the EDM process and oxygen plasma treatment. The dimension of an assembled flap valve is $12[mm]{\times}20[mm]{\times}28[mm]$. The stroke volume of the flap valve is measured for various pressures. And the time of the applied input voltage is varied to change the open time of the valve. When the input voltage of 30[V] is applied for 0.25[s], the minimum stroke volume of the flap valve is $40[{\mu}L]$ at 70 [kPa].

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1942-1947
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• 2003

The valve is the key part which governs the efficiency, noise and reliability of the compressor, so the development of analytical model about valve performance is necessary. As the valve leed is opened and closed by pressure pulsation, the flow characteristic of the refrigerant passing the valve is very important. In the present study, a circular disk with inclination is assumed to be the valve reed of a reciprocating compressor and numerical analysis of three dimensional velocity fields are perfomed for the radial flow through the valve model. The effective flow and force area which are required to predict the efficiency of the valve are measured and compared with the numerical analysis in this research.

• 한국가시화정보학회:학술대회논문집
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• 2003.11a
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• pp.99-102
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• 2003

PIV(Particle Image Velocimetry)was used to visualize the interaction of reed valve of the reciprocating compressor. The valve is the key part which governs the efficiency, noise and reliability of the compressor, so the development of analytical model about valve performance is necessary. As the valve reed is opened and closed by pressure pulsation, the flow characteristic of the refrigerant passing the valve is very important. In the present study, a circular disk with inclination is assumed to be the valve reed of a reciprocating compressor, The mean velocity shows the vortical characteristic of this flow. It is found that the back flow is affected by the height of reed valve of reciprocating compressor.

• Journal of Biomedical Engineering Research
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• v.19 no.3
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• pp.285-290
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• 1998

There are various reports on the fracture of mechanical heart valves implanted in human or animal, and they are pointed out that problems are induced by an erosion of disk surface, due to a cavitation effect. We have been investigating this mechanism using accelerated fatigue tester, and it was found that erosion was enhanced by a compliance effect in the test circuit. In this study, effects of compliance value and location on erosion were discussed, while disk closing velocity was measured by a high speed video camera. It was clarified that faster closing velocity was resulting in a enhancement of erosion on the disk surface.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1633-1638
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• 2003

In case that in-leakage through the valve disk occurs, a numerical study is performed to estimate on thermal stratification phenomenon in the Safety Injection piping connected with the Reactor Coolant System piping of Nuclear Power Plant. As the leakage flow rate increases, the temperature difference between top and bottom of horizontal piping has the inflection point. In the connection point of valve and piping, the maximum temperature difference between top and bottom was 185K and occurred in the condition of 10 times of standard leakage flow rate. In the connection point of elbow and horizontal piping, the maximum temperature difference was 145K and occurred in the condition of 15 times of standard leakage flow rate. In the vertical piping of Safety Injection piping, the near of connection point between elbow and vertical piping showed the outstanding thermal stratification phenomenon in comparison with another region because of turbulent penetration from Reactor Coolant System piping. In order to prevent damage of piping due to the thermal stratification when in-leakage through the valve disk occurs, the connection points between valve and piping, and the connection points between elbow and piping need to be inspected continually.