• The KSFM Journal of Fluid Machinery
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• v.8 no.3 s.30
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• pp.16-25
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• 2005

The purpose of this study is localization of safety relief valves for Nuclear Service. The safety relief valve is the important equipment used to protect the pressure vessel, the steam generator and the other pressure facility from overpressure by discharging the operating medium when the pressure of system is reaching the design pressure of the system. We developed design technology used FEM ' CFM about safety relief valve for Nuclear Service according to ASME (or KEPIC) Code and KHNP's Technical Specification. To prove validity of a design technology, actually, we manufactured and inspected and tested the sample products designed according to a developed technology. The capacity qualification test was achieved according to requirement of ASME(or KEPIC) Code by NBBI and the functional qualification test was achieved according to ASME QME-1 for operating condition in technical specification of KHNP by NLI. Therefore we have to achieve the development of safety relief valves for Nuclear Service with our own technologies.

• The KSFM Journal of Fluid Machinery
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• v.10 no.5
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• pp.46-53
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• 2007

Stem friction coefficient and valve factor are very important parameters for the evaluation of valve performance. In this study, the characteristics of stem friction coefficient and valve factor are analyzed, and thor bounding value is determined. The hydraulic testing is performed for many flexible wedge gate valves in the plant and statistical method is applied to the determination of bounding value. According to the results of this study, stem friction coefficient does not change much with differential pressure, and the bounding value of closing stroke is higher than that of opening stroke. The valve factor of valves with high differential pressure is higher than that of valves with medium differential pressure. It means valve factor is more sensitive to the differential pressure than the stem friction coefficient. Valve factor of the closing stroke is higher than that of opening stroke due to piston effect.

• Journal of Magnetics
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• v.10 no.2
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• pp.52-57
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• 2005

In this research, magnetoresistance (MR) ratio (MR), resistivity, and exchange coupling field $(H_{ex})$ behaviors for sputter deposited spin valves with FeMn antiferromagnetic layer have been extensively investigated by rapid thermal annealing (RTA) as well as conventional annealing (CA) method. 10 s of RTA revealed that interdiffusion was not significant up to $325^{\circ}C$ at the interfaces between the layers when the RTA time was short. The MR of FeMn spin valves were reduced when the spin valves were exposed to temperature of $250^{\circ}C$, even for a short time period of 10 s prior to CA. $H_{ex}$ was maintained up to $325^{\circ}C$ of CA when the specimen was subjected to 10 s of RTA at $200^{\circ}C$ prior to CA, which is $25^{\circ}C$ higher than the result obtained from the CA without prior RTA. Therefore, the stability of $H_{ex}$ could be enhanced by a prior RTA before performing CA up to annealing temperature of $325^{\circ}C$. MR and sensitivity of the specimens annealed without magnetic field up to $275^{\circ}C$ were recovered to the values prior to CA, but $H_{ex}$ was not recovered. This means that reduced MR sensitivity and MR during the device fabrication can be recovered by a field RTA.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.1
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• pp.124-134
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• 1996

In this paper the pressures and flowrate distributions in the loading/unloading piping system of LNG carrier have been investigated in the case of unsteady flow state as well as steady one. Under emergency situation the main cargo pumps are forced to fail, and the ESD(Emergency Shut Down) valves and Stop valves are closed within set-time. The surge pressures according to the variations of valve closing time have been computed to recognize the surge phenomenon due to sudden decrease of flowrate. By means of these analysis results, the most important factors on the in-pipe surge phenomenon of cargo loading/unloading piping system of LNG Carrier are the type of ESD and Stop valves, valve closing time, and the pipe arrangements.

• Korean Journal of Computational Design and Engineering
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• v.15 no.1
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• pp.60-69
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• 2010

Outfitting systems in marine vessels have many kinds of standard parts. Ship CAD system should support the designers with an efficient tool for the modeling of outfitting parts such as pipes and valves. We develop a practical procedure for a part master model that combines ship CAD systems with the industrial standard. Part master or catalogue database of standard equipments is included in the database of ship CAD. The part master makes the associations of three dimensional modeling with the industrial standard. Moreover, it reflects the automatic modeling to maintain attributes that are disclosed in the entity of each part master in order to reduce the modeling time. Entity and attributes of pipe and valves are chosen from JIS(Japanese Industrial Standards) in order to explain the proposed procedure. Suggested procedure explains that three dimensional model of equipment is generated by parsing the pre-defined attributes after the entities of part masters is stored in database.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.1
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• pp.28-35
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• 1995

The fluid flow for a energy transfer is essential for the design and operation of power plants, petrochemical plants and ships including a process. When the operating conditions of a plant are changed or any transitional event occured, the flow controls of a fluid must be performed to follow the new operating state or mitigate the results of a event. Generally these flow controls to accommodate the new operating state of a plant are made by the use of various valves. The refore the design of valves and the related techniques are very important to the system and component designs. However the system and component design are not familiar with the practical theory of the valve since the derivative procedures of the flow equations in a valve are difficult and it is not easy to found the theoretical foundamentals and informations about the design of a valve from the present references. In this study the flow equations applicable to a valve for liquid are theoretically derived in detail. And the definition of valve reynolds number and its boundary values between the tubulent and laminar flow is described compared with the values of a circular pipe flow.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.555-561
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• 2003

The experimental apparatus is designed and installed to measure the disc positions with flow velocity, $V_{open}\;and\;V_{min}$ for 3 inch and 6 inch swing check valves. The minimum flow velocity necessary to just open the disc at a full open position is referred to as $V_{open}\;and\;V_{min}$ is defined as the minimum velocity to fully open the disc and hold it without motion. In the experiments, $V_{min}$ is determined as the minimum flow velocity at which the back stop load begins to increase after the disc is idly opened or the oscillation level of disc is reduced below $1^{\circ}$. The results show that the $V_{min}$ velocities for 3 inch and 6 inch swing check valves are about 15.6% and 4.8% higher than the $V_{open}$ velocities, respectively. Although the experiments were done with the stable uniform flow, additional experiments will be performed to determine the effects of the upstream disturbances.

• Journal of Biomedical Engineering Research
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• v.23 no.5
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• pp.391-395
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• 2002

Shunt valves used to treat patient with hydrocephalus were numerically simulated to investigate influence of pressure pulsation on their flow control characteristics. We modeled flow orifice through the shunt valve and imposed pulsating pressure and valve diaphragm movement to compute flow through the valve. The results of our study indicated that flow rates increased more than 40% by introducing pressure pulsation and diaphragm movement on the shunt valve. Our results demonstrate the pressure-flow control characteristics of shunt valves implanted above human brain may be quite different from those obtained by syringe pump test just after manufacture that induces uniform pressure.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.6
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• pp.484-495
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• 2017

In HVDC thyristor valves, more than 95% of heat loss occurs in snubber resistors and valve reactors. In order to dissipate the heat from the valves and to suppress the electrolytic current, water with a high heat capacity and a low conductivity of less than 0.2 uS/cm must be used as a refrigerant of the heat sink. The cooling parts must also be arranged to reduce the electrolytic current, whereas the pipe that supplies water to the thyristor heat sink must have the same electric potential as the valve. Corrosion is mainly caused by electrochemical reactions and the influence of water quality and leakage current. This paper identifies the refrigerants involved in the ionization, electrical conductivity, and corrosion in HVDC thyristor valves. A method for preventing corrosion is then introduced. The design of the heat sink with an excellent heat radiation is also analyzed in detail.

• Journal of Magnetics
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• v.7 no.4
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• pp.147-150
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• 2002

The pinning direction, the spin flop behaviors and the magnetoresistive properties in top synthetic spin valve structure [NiFe/CoFe/Cu/CoFe (t$_{p2}$)/Ru/CoFe (t$_{p1}$)/IrMn] were investigated. The magnetoresistive and pinning characteristics of synthetic spin valves strongly depended on the differences in the two pinning layer thickness, ${\Delta}t(=t_{p2}-t_{p1})$. In contrast to the conventional spin valves, the pinning direction (P1) was canted off with respect to the growth field axis with ${\Delta}t$. We found that the canting angle ${\Phi}$ had different values according to the annealing field direction and ${\Delta}t$. When the samples were annealed at above the blocking temperature of IrMn with zero fields, the canted pinned layer could be set along the growth field axis. Because the easy axis which was induced by the growth field during deposition is still active in all ferromagnetic layers except the IrMn at $250{^{\circ}C}$, the pinning direction could be aligned along the growth field axis, even in 0 field annealing.