• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.4
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• pp.175-182
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• 2000

The back-light inverter used in the laptop computer is designed in this paper. It has been difficult for electromagnetic transformer to enhance the efficiency and compact profile of the inverter. In this paper, (1) the piezoelectric transformer (PT) is used for reducing the loss; (2) the volumes of core and winding coil are used in electromagnetic transformer, and (3) the half-bridge series parallel resonant circuit is used in the driver of the inverter. The modified PT for this paper and the equivalent circuit are supported by the simulation program. The result of the experiment shows more than 91% improvement in terms of the efficiency.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.7
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• pp.409-416
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• 2004

This paper presents the selection method o( the input current wave forms for the thrust force ripple of linear pulse motor (LPM). We have developed and tested a prototype 2-phase 4-poles LPM with the permanent magnet and its control driver. To obtain the thrust performance curve of LPM, the performance curve at the air gap and the thrust are calculated and estimated by the analytical method on the base of the magnetic equivalent circuit and the finite element method. And, the thrust characteristics at the static operation state are analyzed and experimented with the respect to the input wave forms such as the rectangular, the triangular micro-step and the sine micro-step wave forms to investigate the thrust ripple and the vibration effects of LPM.

• Convergence Security Journal
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• v.8 no.2
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• pp.27-34
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• 2008

In this paper, we designed and implemented mobile object automatic system based on senor networks for telematics. For developing this system, we gather the various sensing data through wireless communication method using zigbee sensor networks and analyze them in monitoring equipment. And we enable the driver to recognize the car state information on the whole by interfacing analyzed data to telematics unit. And, we implemented automatic controller that can control temperature and humidity in car automatically by actuating air conditioner based on the data that was monitored throughout temperature sensor, humidity sensor and brightness sensor based on sensor networks.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2537-2540
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• 2001

The purpose of this study is to examine the calculated method of loss characteristics of full-bridge eletronic ballast for 250Watt HID lamps by approximated modeling. These lamps have the most emit effiency and color rendering. Especially, the majority of losses appear to the MOSFET do full-bridge, L of output terminal and driver IC, besides losses occur to the R in the ballast. These losses cause heating and breakage of MOSFET. When HID-lamp arrivals the steady-state, loss of ballast is measured 9% and analyzed value is 8% approximately. Accordingly it is not too much to say that greater part of losses is examined.

• Journal of Power Electronics
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• v.6 no.3
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• pp.264-270
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• 2006

Magnetic levitation transfer systems are useful for transfer tools in clean rooms and positioning control systems with high precision because of frictionless characteristics. In this paper, the new method is proposed which is a sensorless position. At first, the magnetic levitation is performed by state feedback control with a disturbance observer for each of six axes of the movement of a levitated vehicle. The position of the vehicle is then estimated as the disturbance term of a disturbance observer for a pitch angle which is one of the control axes for the magnetic levitation. In addition, the positioning force is generated by the pitch angle control which gives a tilt to the levitated vehicle so that it generates the horizontal component of force.

• International Journal of Automotive Technology
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• v.6 no.5
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• pp.529-536
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• 2005

This paper presents a novel design of a fuzzy control strategy (FCS) based on torque distribution for parallel hybrid electric vehicles (HEVs). An empirical load-regulating vehicle operation strategy is developed on the basis of analysis of the components efficiency map data and the overall energy conversion efficiency. The aim of the strategy is to optimize the fuel economy and balance the battery state-of-charge (SOC), while satisfying the vehicle performance and drivability requirements. In order to accomplish this strategy, a fuzzy inference engine with a rule-base extracted from the empirical strategy is designed, which works as the kernel of a fuzzy torque distribution controller to determine the optimal distribution of the driver torque request between the engine and the motor. Simulation results reveal that compared with the conventional strategy which uses precise threshold parameters the proposed FCS improves fuel economy as well as maintains better battery SOC within its operation range.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.183-183
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• 2007

Bimodal Tram is a new public transportation system combined subway with bus and consists of variable electric equipment to accomplish the comfortness, reliability, safety and so on. One of them is VCU(Vehicle Control Unit) for Performing driver's cmmand and monitoring the state of other equipment. To lessen the wiring and the interference of outer electromagnetic noises is very important things for bimodal tram with complicated configuration of electric equipments. This paper has investigated the application of CAN(Controller Area Network) communication method for VCU which has display, central unit and several nodes that are connected with other electric equipments(HVAC, door controller etc). We designed and manufactured the prototype of VCU which eventually will be installed on bimodal tram being developed in KRRI at present.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.4
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• pp.34-41
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• 1993

The dc servo motor has been often used as the driver for a position control system, because the performance of the control is excellent on the speed and position control. When the unknown disturbance and/or the varying quantity of load is imposed on the position control system, the response of the system has the steady and/or the transient state error.The objective of this work is to demonstrate the principles, design methodologies and implementation of a servo controller for reducing the error in the position control system using the dc servo motor. The coefficients of a servo controller are computed by the pole placement.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.597-600
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• 2012

본 연구의 목적은 눈 폐쇄 상태 검출 알고리즘을 개발하고, 그것을 바탕으로 모바일 환경의 졸음운전 감지 시스템을 구현하는 것이다. 개발한 알고리즘은 검출된 눈 영역의 이미지를 히스토그램 분석을 통해 실험적으로 얻은 문턱 값으로 이진화 시킨 후 운전자 눈의 폐쇄 상태를 판단한다. 구현한 시스템은 얼굴과 눈 검출이 완료된 상태에서 검출된 눈이 폐쇄 상태인지를 판단한다. 폐쇄 상태인 경우 이상태가 지속되면 시스템은 운전자가 졸음운전 상태임을 감지하고 경고해준다. 자원이 제한된 모바일의 특성상 이미지 처리의 정확성뿐만 아니라 처리속도의 효율성도 중요한데 이 특성에 맞는 알고리즘을 개발하였고, 이를 바탕으로 졸음운전 감지 시스템 구현에 성공하였다.

• International Journal of Computer Science & Network Security
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• v.21 no.12
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• pp.193-202
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• 2021

The article is devoted to current issues of the development of e-commerce, which is gaining more importance in the conditions of widespread quarantine restrictions. As a result, of the research the importance of digitalization as a driver of economic development is substantiated and the main business models of e-commerce and their modifications are examined. The peculiarities of e-commerce in the context of digital economy were analyzed and their current state was established. Identified the main trends in the development of e-commerce at the current stage, which allowed to identify problem areas that require further study and evaluation. Presented the results of the market research of decorative cosmetics, based on which the summarized set of problems that affect the online sales in this segment of the market.