• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.984-987
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• 2000

In switched reluctance motor(SRM) drive, it is necessary to synchronize the stator phase excitation with the rotor position. Therefore the rotor position information is an essential. Usually optical encoders or resolvers are used to provide the rotor position information. These sensors are expensive and are not suitable for high speed operation. In the paper, the low cost linear encoder suitable for the practical and stable SRM drive is proposed and the control algorithm to provide the switching signals using the simple digital logic circuit is also presented in this paper. It is verified from the experiments that the proposed encoder and logic controller can be a powerful candidate for the practical low cost SRM drive.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.684-686
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• 2000

Switched reluctance motor(SRM) has the advantages of simple structure, low rotor inertia. and high efficiency. However position sensor is essential in SRM in order to synchronize the phase excitation to the rotor position. The position sensors increase the cost of drive system and tend to reduce system reliability. This paper investigates the speed control of sensorless SRM in which the phase current and change rate are utilized in position decision, and the period of dwell angle is variable by compensating the rotor angle for speed control. The proposed system consists of position decision. phase locked loop controller, switching angle controller and inverter. The performances in the proposed system are verified through the experiment.

• 동서간호학연구지
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• 제21권2호
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• pp.133-139
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• 2015

Purpose: The purpose of this study was to identify the effects of thermotherapy on abdominal distension and pain during colonoscopy. Methods: This study used a nonequivalent control group and a non-synchronize design. Twenty-nine participants were assigned in an experimental group and 29 in the control group. For the experimental group, electronic heating pad was applied before test throughout the entire procedure. Results: Abdominal distension and total time required for colonoscopy significantly were lower in the experimental group than those in the control group. Conclusion: The results suggest that thermotherapy can be effective to improve abdominal distension and colonoscopy time in patients with colonoscopy. Therefore, thermotherapy can be recommended for those patients undergoing of colonoscopy.

• 제어로봇시스템학회논문지
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• 제16권2호
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• pp.194-201
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• 2010

This paper discuss a performance evaluation of the synchronization algorithm for hybrid networks in industrial environments. The proposed algorithms minimizes synchronization errors which were caused from channel, Propagation, and frequency delays. The modified RBS and offset synchronization methods can be operated by adjustment parameters. The differential BP (Back-off Period) adjustment can synchronize the local time of each node with master node's time in hybrid networks. For the performance analysis, the data transmission time between the wired and wireless devices are investigated. The experimental results show the performance evaluations in terms of the polling service time and an average end-to-end delay.

• 한국음향학회지
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• 제20권2호
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• pp.16-20
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• 2001

비디오 프로그램 색인 및 검색에 있어서 비디오 프로그램을 의미 있는 부분으로 분할하는 것, 즉 내용기반 비디오 프로그램 분할은 중요하다. 본 논문에서는 내용기반 비디오 프로그램 분할을 위해 음성인식기술을 이용하는 새로운 방법을 제안한다. 제안한 방법은 음성신호와 캡션 (Closed Caption)의 정확한 동기를 위해 음성인식 기법을 사용한다. 실험을 통하여 내용기반 비디오 프로그램 분할을 위해 제안한 방법의 가능성을 확인하였다.

• 반도체디스플레이기술학회지
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• 제14권4호
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• pp.72-77
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• 2015

Three-level diode clamped multilevel inverter, generally known as neutral point clamped (NPC) inverter, has an inherent problem causing neutral point (NP) potential variation. Until now, the NP potential problem of variation has been investigated and lots of solutions have also been proposed. This paper presents a neutral point voltage control technology using the anti-windup PI controller and offset technology of PWM (Pulse Width Modulation) to control the variation of NPC 3-phase three-level inverter neutral point voltage. And the proposed algorithm is tested and verified using a PLL (Phase Locked Loop) in order to synchronize the phase voltage from the line voltage of grid. It significantly improves the voltage balancing under a solar fluctuation conditions of the inverter. Experimental results show the good performance and effectiveness of the proposed method.

• International Journal of Fluid Machinery and Systems
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• 제6권4호
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• pp.213-221
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• 2013

The characteristics of the thrust for ship propulsion equipment directly driven by air compressed by pressure fluctuation in a blower piping system are investigated. The exhaust valve is positioned upon the air ejection hole in the discharge pipe in order to induce the large-scale pressure fluctuation, and the effects of the valve on the pressure in the pipes and the thrust for the propulsive nozzle are examined. The pressure in the pipes decreases immediately after the valve is opened, and it increases just before the valve is closed. The thrust for the propulsive nozzle monotonically increases with increasing number of revolutions and depth. The interfacial wave in the nozzle appears in the frequency of approximately 4Hz, and it is important for the increase of the thrust to synchronize the opening-closing cycle for the exhaust valve with the generation frequency of the interfacial wave. The finite difference lattice Boltzmann method is helpful to investigate the characteristics of the flow in the nozzle.

• Journal of Communications and Networks
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• 제17권2호
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• pp.203-209
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• 2015

Although mobile applications are an essential characteristic of wireless sensor networks, most existing media access control (MAC) protocols focus primarily on static networks. In these protocols, fixed periodic neighbor discovery and schedule updating are used to connect and synchronize neighbors to provide successful data transmission; however, they cannot adapt to mobile speed variation and degrade the network performance dramatically. In this paper, we propose a mobile-supporting mechanism for MAC protocols, in which the decision to update the neighbors of a mobile node is made adaptively according to the mobile speed. Analysis and simulation results demonstrate that the mechanism efficiently avoids the disconnection of amobile node from its neighbors and achieves a better performance as compared with fixed periodic neighbor discovery.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.511-513
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• 2004

In a switched reluctance motor drive, it is important to synchronize the stator phase excitation with the rotor position, because the position of rotor is an essential information. In the high-speed region, switching angles are fluctuated back and forth out of the preset value, which is caused by the sampling period of the microprocessor. In this paper, a low cost analog encoder suitable for practical applications is proposed. The validity of the proposed analog encoder with a proper logic controller is verified from the experiments.

• 한국정보통신학회논문지
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• 제2권1호
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• pp.79-85
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• 1998

NBDP시스템에서 9디지트 해상이동식별번호는 7-신호 식별부호로 변환되어 호출국을 자동식별하기 위한 위상동기절차를 거쳐 정보송신국(ISS)의 클럭에 동기 되는데 사용된다. 본 연구에서는 NBDP시스템의 ARQ 모드에서의 페이징절차에서, 호출동기를 위한 자동식별 동기방법과 식별신호간의 변환 및 점검합신호의 검출 알고리즘을 정리하고, 호출의 위상동기를 ITU-R에서 정하고 있는 조건보다 더 빠르게 동기될 수 있는 위상동기방법을 제안하였다.