• ETRI Journal
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• v.20 no.3
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• pp.284-300
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• 1998

A new thermosyphon cooling module (TSCM) has designed, fabricated and tested to cool the multi-chip module consists of a cold plate and an integrated condenser. With an allowable temperature rise of $56^{\circ}C$ on the surface of the heater, the cooling module TSCM can handle a heat flux of about 2.7 $W/cm^2$ using R11 as working fluid. The transient characteristics of the cooling module have been proved to be excellent: that is, when a heat load is applied inside of the system, steady state can be achieved within 10 to 15 minutes. It has been found that the length of the vapor channel between the cold plate and the condenser in addition to the ambient and the condenser temperatures affect the system performance.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.7
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• pp.48-55
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• 1997

An adaptive output feedback controller is designed for tracking control of an n-link robot manipulator with unknown load. High-gain obwserver that is used to estimate joint velocities is designed to avoide the restriction of the allowable variation range of unknown parmeters as well as improve the state estimation error. We saturate the control inut outside a domain of interest and use an adaptive law with a parameter projection feature to guarantee boundedness of all the trajectories in the closed-loop system. Simulation resutls on a 2-link manipulator illustrate that when the speed of the high-gain observer is sufficiently high, the proposed controller recovers the performance under state feedback control.

• Design & Manufacturing
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• v.8 no.1
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• pp.40-44
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• 2014

As a rotating machine element, plastic gears are more and more widely used in such as industrial machine element, since plastic gear is lighter, higher wear-resistance, and higher vibration absorbing ability than metal gears. When operating plastic parts, tooth breakage and fatigue life shortened due to increasing number of applying load and tooth flank temperature rising, such that accuracy of plastic gears is divided from allowable range to cause vibration and noise. On this study, a internal plastic gears are developed which improved the filling balance molding process by a new injection mold structure. The new mold structure called HR3P(hot runner type 3plate mold). As the result from this studies, we obtained a very accurate roundness internal gears by using design of experiment.

• Journal of the Korea Concrete Institute
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• v.11 no.6
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• pp.113-119
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• 1999

Fatigue failure is a phenomenon such that structures under cyclic service load is failed by sudden brittle manner. Therefore, in order to obtain structures safety against the fatigue failure during their service lifes, fatigue characteristics should be considered for design and analysis of the structures. As stress range of prestressed (PS) tendons, which governs fatigus characteristic of prestressed concrete (PSC) structures, increases with increased use of partial prestressig, it is more necessary to consider fatigue characteristics of PS tendons. In this paper, direct-tension fatigue experiments with special specimen-setting devices are carried out to obtain fatigue characteristics of domestic low relaxation PS strands having different diameters and PS strands connected with coupler. Then, allowable stress range of fatigue for PSC beams using low relaxation strands are presented for the fatigue examination of prestressed concrete beams applied cyclic loading.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.70-76
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• 2013

This study investigates structural durability through the analyses of stress, fatigue life and vibration damage at bike carrier basket. As model 2 has less stress and deformation than model 1 on static structural analysis, model 2 becomes more durable than model 1. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. The amplitude deformations become highest at maximum response frequency of 2400Hz in cases of models 1 and 2. As the values of maximum equivalent stresses become within the allowable material stresses at two holes at the upper parts on models 1 and 2, these models become safe. The structural result of this study can be effectively utilized with the design of bike carrier basket by investigating prevention and durability against fatigue or vibration damage.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.3
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• pp.544-552
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• 2002

Recommended seismic design guide for the flat bottom vortical-cylindrical oil storage tanks in KS B 6225 is presented. Under earthquake excitations, the hydrodynamic pressure exerted on the tank walls produces overturning moment which may cause either a failure of the anchors or a buckling of the tank shell near its base. The basis for establishing design loads due to hydrodynamic pressure is described including seismic zone risk map in Korea, zone coefficients and the essential facilities factor. This procedure for calculating applied compressive stress on the shell base subjecting to seismic load and for estimating the allowable buckling stress is described.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.901_902
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• 2009

This paper describes the development of a three-phase Line-Interactive DVR(Dynamic Voltage Restorer), which is applied to Hybrid detection method and super-capacitor. The operational feasibility was verified through computer simulations with PSCAD/EMTDC software, and experimental will be work with 3kVA prototype. The developed system can compensates the input voltage sag and interruption within 2ms, in which the maximum allowable sensitive load, such as computer, communication equipment, automation equipment, and medical equipment. The developed system has a simple structure to be easily implemented with commercially available components and to be highly reliable in operation.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.2
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• pp.1-5
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• 2010

The efficient beam members for modern greenhouse need to be much lightweight with the required flexural and buckling strength. To confirm the applicability and practicality of the trussed web beam recently proposed for column and beam members of greenhouse, the flexural behavior and buckling characteristics were analyzed by the finite element approach. On the basis of analytical studies, the member design process was presented considering the lateral and local buckling behavior. Also, two improved alternatives which were capable of retaining the lateral and local buckling effectively were suggested.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.130-132
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• 2008

This paper describes the current characteristics of outage generator for microgrid in outage mode operation. The outage can be generated with 3-phase voltage disturbance generator. The STS current becomes very huge during the first cycle of the outage, and the magnitude of the current depends on the time impedance, series transformer leakage inductance, interfacing reactor of PCS, and the maximum allowable PCS output current. The current and load voltage waveform are analysed through simulation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.1
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• pp.41-46
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• 2005

Most of LV customer have applied the 3-phase four wire system distribution system because it has advantage of supplying both of 1-phase & 3-phase loads simultaneously. Due to its structural simplicity, it is more convenient for use rather than the conventional separated scheme. But voltage unbalance more commonly emerges in individual customer loads due to phase load unbalance, especially where, single-phase power loads are used. Voltage unbalance factor(VUF) represents the loss of symmetry in the supply(magnitude and angle). It leads some problems such as de-rating or power losses. In this paper, voltage and current waveform in the actual fields have been measured and analyzed in relation with internationally allowable voltage unbalance limits.