• Journal of Industrial Technology
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• v.19
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• pp.261-268
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• 1999

It is a main object to find out the effect of curvature of pipe on the thermal flow field in copper pipe. the toroidal coordinate system is chosen for this project. 3-D numerical works are done by a commercial code, PHOENICS. The flow and temperature field are simulated and analysed on the view point of variation of pressure and temperature with Dean number. The results show that the strong recirculation phenomena and secondary flow are established and then a lot of pressure drop along main flow direction occurs at the curved portion of pipe and the temperature variation has a reversed trend of pressure variation along the axis of pipe.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.147-149
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• 2000

Samsung Superconducting Test Facility (SSTF) will be built at SAIT, Taejeon. The superconducting cables to be used for KSTAR magnets are going to be tested in SSTF. The background magnet in SSTF is needed to simulate harsh magnetic environment for testing short CICC samples as well as full-scale magnets. The main coils can make central magnetic field of up to 8 Tesla and the blip coils can maintain fast ramping rate of 20T/s. The cancellation coils reduce the disturbance of main coils due to blip coils. The magnetic field distribution of these coils has been obtained with finite element method as well as the direct integration method.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1721-1723
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• 2002

This paper deals with the analysis of field condition for earth leakage current alarming system in the stage lighting, stage sound stage machinery installation. These analyses of field condition were carried out in accordance with investigating an installation of earth leakage current alarming system with respect to a main line of power source, dimmer, sound equipment, machinery mobile unit equipment and so on. As a result of analyses. The earth leakage current alarming system has been installed only a part of the main line of power source and the probability of places which were installed was less than 50(%). Therefore, it is desirable that the earth leakage current alarming system is installed at places which are suitable, for example, dimmer, each kind machinery etc. in order to prevent electrical hazard.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.9
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• pp.79-84
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• 2010

This paper discusses the control of generator field using dual IGBT PWM regeneration method to target brushless synchronous generator. If one of PWM bridges happens to fault, it transfers automatically and can be in charge of full load. Also it has an advantage of the operation which UPS connected in parallel with PWM bridge can supply power to excitation system in condition of main power loss. This PWM system supplies field current to generator in one quadrature operation, regenerates field coil energy to main power supplier in four quadrature operation. We designed, manufactured and applied the first trial product at J-power plant.

• Journal of the Korean Mathematical Society
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• v.55 no.6
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• pp.1321-1336
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• 2018

In this paper, we obtain some necessary and sufficient conditions for the Reeb vector field of a trans-Sasakian 3-manifold to be minimal or harmonic. We construct some examples to illustrate main results. As applications of the above results, we obtain some new characteristic conditions under which a compact trans-Sasakian 3-manifold is homothetic to either a Sasakian or cosymplectic 3-manifold.

• Honam Mathematical Journal
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• v.33 no.3
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• pp.381-391
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• 2011

One of the main interesting things of a matroid theory is the representability by a matroid from a matrix over some field F. The representability of uniform matroid $U_{m,n}$ over some field are studied by many authors. In this paper we construct a matrix representing $U_{3,6}$ over the field GF(4). Also we find out matrix of the affine matroid AG(2, 3) over the field GF(4).

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.87-92
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• 2001

This technical note is intended to introduce a state-of-the-art offshore construction vessel. This unique vessel is for multi-purpose Field Development Ship (FDS) for deepwater to ultra-deepwater. The FDS is a construction vessel with dynamic positioning (DP) system intended to develop offshore oil and gas field in water depth up to 3000 m. The design criteria and main capacities of the vessel are discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.7
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• pp.520-526
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• 2002

Identification of noose sources, their locations and strengths, has been taken great attention. The methods that can identify noise sources normally assume that noise sources are located in a free field. However, the sound in a reverberant field consists of that coming directly from the source plus sound reflected or scattered by the walls or objects in the field. In contrast to the exterior sound field. reflections are added to sound field. Therefore, we haute to consider the reverberation effect on the source identification method. The main objective of this paper is to identify noise source in the reverberant field. At fist, we try to identify noise sources in a rigid wall emc;psire using the beamforming method. In many cases of practical interest, the wall has admittance so that random reflections occur in an enclosure. In this paper, we assumed the complex reverberant field in the enclosure to be the sum of plane caves with random Incidence and magnitude. Then we try to explain effects of reverberant field at interior source identification.

• Membrane and Water Treatment
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• v.11 no.1
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• pp.49-57
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• 2020

The effect of Combined Sewer Overflow on the river system was investigated throughout three preliminary field tests and three main ones. As a result of the study, Combined Sewer Overflow did not affect water qualities on the main stream since the concentration of the main stream did not significantly changed during rainfall events although the water quality of tributaries has rapidly deteriorated due to the influence of the Combined Sewer Overflow during rainfall events. The main cause of the result is that the flow rate of the tributaries is considerably lower than that of the main stream, so that the tributaries with deteriorated water quality during rainfall events did not significantly affect the quality of the actual main stream. Therefore, the water quality of the Kumho River is more affected by the wastewater treatment facilities that discharges water continuously to the main stream than pollutants from non-point pollution sources during rainfall events. As a result, managements for discharges from wastewater treatment facilities should be strengthened in order to improve the water quality of the river.

• Korean Journal of Mathematics
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• v.18 no.1
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• pp.21-28
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• 2010

In the unified field theory(UFT), many works on the solutions of Einstein's equation have been published. The main goal in the present paper is to obtain some geometric results on a particular solution of Einstein's equation under some condition in even-dimensional UFT $X_n$.