• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.51-54
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• 2000

This paper describes the fixed-point DSP implementation of a CELP(code-excited linear prediction)-based speech coder. The effective realization methodologies to maximize the utilization of the DSP's architectural features, specifically Parallel movement and pipelining are also presented together with the implementation results targeted for the ITU-T standard G.723.1 using Motorola DSP56309. The operation of the implemented speech coder is verified using the test vectors offered by the standard as well as using the peripheral interface circuits designed for the coder's real-time operation.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.119-120
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• 2013

Wind turbines as a power distribution system linked to the driving operation according to the characteristics of the distribution system can be adversely affected by a change of circumstances, depending on Distribution Systems with driving characteristics of a wind turbine can be affected. Thus according to the grid-tied wind turbines and transient suppression of the distribution lines and distribution lines outside of the accident in order to maintain stable power supply to supply reactive power efficient system is necessary to keep the voltage constant. In this paper, we substantiated in Jeju Hangwon 12 Unit Level 1MVA STATCOM system configuration, control, configure, and test results will be introduced.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2013-2015
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• 1997

Elevator stops emergently when power failures happen during operation. In that case, the passenger should wait with frightened in the car untill they are rescued by repair man or power resumes. This paper describes an automatic landing device for power-failure(ALP) that consists of UPS and battery charge control system. The excellence of the ALP operation is verified by experiments in elevator test tower.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.468-473
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• 2004

The magnetic jack type Control Element Drive Mechanism (CEDM) had been developed and verified through electromechanical testing including the testing of the magnetic force required to lift the control element assembly. It would become inefficient in view of cost and time for parametric studies to be performed by test to improve the CEDM system. So it becomes necessary to develop a computational model to simulate the electromagnetic characteristics of the CEDM in order to improve the CEDM design efficiently. In this paper it is presented that the electromagnetic analysis using a 2D axisymmetric FEM model has been carried out to simulate the operation of the latch magnet of the CEDM to generate a current trace for latch coil. The results show the calculated current trace is very similar to the real current trace taken from the CEDM.

• Journal of Biosystems Engineering
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• v.2 no.1
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• pp.81-84
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• 1977

This study was conducted to develop the leveller suitable for power tiller which has been widely used in Korea. Field test was carried out to determine its performance in accordance with the tilt angles of blede, forward velocities , and the length of blade . The results are follows ; 1. Earth moving capacity of the standard leveller was found to be 90~95kg of soil per one swath while working at the 2nd ~4th gears of forward speed. 2. Work performance of model leveller was 2 , 3, 4 times higher than manual operation in distributing additional soil of thickness 6mm , 12 mm and 24 mm on paddyland, respectively. 3. Levelling performance of model leveller on the inclined fields was 7 ~9 times higher than manual operation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1318-1320
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• 2007

Fan noise prediction method is presented for air conditioning and/or cooling system applications where fan acts as an internal equipment having very complicated flow interaction with other various system components. The internal flow paths and distribution in the fan-applied systems such as computer or air conditioner are analyzed by using the FNM(Flow Network Modeling) with the flow resistances for flow elements of the system. Based on the fan operation point predicted from the FNM analysis results, the present fan noise model predicts overall sound power, pressure levels and spectrum. The predictions of the flow distribution, the fan operation and the noise level in electronic system by the present method are well agreed with 3-D CFD and actual noise test results.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.11
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• pp.37-45
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• 2002

This paper presents the field-dependent Bingham characteristics and damping force control of an electro-rheological (ER) fluid under squeeze mode operation. The squeeze force of the ER fluid due to the imposed electric field is analyzed and an appropriate size of the disk-type electrode is devised. On the basis of the theoretical model of the ER fluid under squeeze mode operation, the yield stress and response speed of the ER fluid are distilled from the time responses of squeeze force to the step electric potentials. Measured squeeze forces under various excitation conditions are compared with the predicted ones from Bingham model and time constant obtained at the transient response test. In addition, the controllability of the field-dependent damping force of the ER fluid under squeeze mode is experimentally demonstrated by implementing simple PID controller.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.309-312
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• 2005

The need for LBS (Loc,ation Based Services) is increasing due to the wnespread of mobile computing devices and positioning technologies~ In LBS, there are many applications that need to manage moving objects (e.g. taxies, persons). The moving object join operation is to make pairs with spatio-temporal attribute for two sets in the moving object database system. It is import and complicated operation. And processing time increases by geometric progression with numbers of moving objects. Therefore efficient methods of spatio-temporal join is essential to moving object database system. In this paper, we apply spatial join methods to moving objects join. We propose two kind of join methods with TB- Tree that preserves trajectories of moving objects. One is depth first traversal spatio-temporaljoin and another is breadth-first traversal spatio-temporal join. We show results of performance test with sample data sets which are created by moving object ,generator tool.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1224-1225
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• 2011

This paper proposes a novel soft-switching interleaved boost converter composed of two shunted elementary PFC boost conversion units and an auxiliary inductor. This converter is able to turn on both the active power switches at zero voltage to reduce their switching losses and evidently raise the conversion efficiency and power factor. Since the two parallel-operated elementary boost units are identical, operation analysis and design for the converter module becomes quite simple. A laboratory test circuit is built, and the circuit operation shows satisfactory agreement with the theoretical analysis. The performance of the proposed PFC rectifier was evaluated on an experimental 300[W] PFC prototype.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.9
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• pp.952-960
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• 2008

Fan noise prediction method is presented for air conditioning, automobile and electronic cooling system applications where fan acts as an internal equipment having very complicated flow interaction with other various system components. The internal flow paths and distribution in the fan-applied systems such as computer or air conditioner are analyzed by using the FNM(flow network modeling). Fan noise prediction method comprises two models for the discrete frequency noise due to rotating steady aerodynamic lift and blade interaction and for the broadband noise due to turbulent boundary layer and wake vortex shedding. Based on the fan operation point predicted from the FNM analysis results and fan design parameters, the present far noise model predicts overall sound pressure level and spectrum. The predictions for the flow distribution, the fan operation and the noise level in air cooling system by the present method are well agreed with 3-D CFD and actual noise test results.