• 센서학회지
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• 제27권6호
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• pp.421-426
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• 2018

To develop a piezoelectric inkjet printhead for high-resolution and high-speed printing, we studied the characteristics of an inkjet printhead by analyzing the major design parameters. An analytical model for the inkjet printhead was established, and numerical analysis of the coupled first-order differential equation for the defined state variables was performed using state equations. To design the dimension of the inkjet printhead with a driving frequency of 100 kHz, the characteristics of the flow rate and discharge pressure of the nozzle were analyzed with respect to design variables of the flow chamber, effective sound wave velocity, driving voltage, and voltage waveform. It was predicted that the change in the height of the flow chamber does not significantly affect the Helmholtz resonance frequency and discharge speed of the nozzle. From the analysis of change in flow chamber width, it is observed that as the width of the flow chamber increases, the ejection speed greatly increases and the Helmholtz resonance frequency decreases considerably, thereby substantially affecting the performance of the inkjet printhead.

• 한국심리학회지 : 문화 및 사회문제
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• 제12권5호_spc
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• pp.149-167
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• 2006

고령화가 다른 국가에 비해 상대적으로 빠르게 진행되고 있는 상황에 대비한 고령운전자의 연구가 부족한 실정이다. 본 연구는 고령운전자의 교통사고 원인을 신체적 능력저하보다도 심리적 요인의 변화에 입각하여 고찰해 보려고 한다. - 고령운전자의 교통사고 고령운전자의 교통사고에서 가장 두드러지게 나타나는 행동적 특징은 좌회전시 발생하는 교통사고가 많다는 것이다. 그리고 사고장소에 따른 분석결과에 의하면, 교차로에서 발생하는 사고가 많다는 것이 확인되었다. - 고령운전자의 조심성과 보상행동 고령운전자의 조심성이 운전행동에 미치는 알아보기 위하여 운전자의 운전확신수준을 비교해 보았다 운전확신수준은 4개 요인으로 구분되었고, 고령운전자와 젊은 운전자의 운전확신수준 차이를 검증한 결과를 보면, 고령운전자의 운전확신수준이 젊은 운전자에 비해 현저하게 떨어지는 것을 알 수 있었다 그리고 좌회전을 선택시 소요되는 시간을 분석하여 고령운전자의 조심성을 이해하려고 하였다 고령운전자는 젊은 운전자에 비해 선택소요시간이 현저하게 길어진다는 사실을 발견하였다. - 고령운전자의 운전일탈행동 연령에 따른 운전일탈행동의 변화를 보면, 연령이 증가함에 따라 운전일탈행동의 위반, 오류, 착오의 평균 점수는 감소하는데, 각 요인이 감소하는 정도는 차이가 있었다. 위반점수는 연령의 증가에 따라 급격하게 감소하는 모습을 보이는데 비해 오류와 착오점수는 연령의 증가에 따라 완만하게 감소하는 경향을 보였다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.32-37
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• 2000

In a high speed spindle system, it is very important to monitor the operation of the spindle to prevent catastrophic damage to the system. Widely used sensors for monitoring are eddy-current and capacitive types. These sensors provide high accuracy of monitoring, but their steep prices lead to expensive high speed spindle system. The main god of our research is to develop technology to produce high speed spindle system utilizing magnetic bearings. As active magnetic bearings require position sensors for feedback control, a noncontact position sensor is bang developed as a part of this main goal. Once developed, it will contribute to affordable high speed spindle system. In this paper, we report the selection process of the sensor types and the experimental results with driving circuits.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.98-100
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• 2008

This paper deals with dynamic torque of PM Synchronous Motor (PMSM) according to driving method. The driving method is selected considering harmonic characteristics with the PMSM.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.423-426
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• 1999

This paper describes a driving scheme of the series hybrid electric vehicle that we have developed. Both series HEV and parallel HEV are well known. We chose series HEV because it provides good energy efficiency in urban driving and operates in all-electric mode in performance. And engine-Generator is driven at constant speed with constant load to maintain the low emission. And the battery supplies power during high-load and receive energy during low-load

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.151-154
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• 1999

This paper presents a driving method of 3-phase 4-poles SRM(switched reluctance motor) drived by switching angle control. In this study, the switching angle is determined from approximated analysis and computer simulation by using MATLAB for high efficiency according to the speed and torque required by load, and then microcontroller controls the switching angle of asymmetrical inverter in SRM driver. Also, we experiment the maximum forque driving and maximum power driving by controlling switching angle available to electric vehicle.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.97-100
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• 2009

A negative waveform was studied to improve the driving characteristics of reset and address periods in ac PDP. Comparative experiments between negative and conventional positive waveforms were performed with 42-inch XGA PDP module. The negative waveform showed lower breakdown voltage than the conventional positive waveform in reset period. Due to its weak and stable discharge during reset period, the contrast ratio was improved by decreasing the black luminance. During address period, the discharge time-lag was measured. The formative time lag ($=T_f$) of negative waveform was improved about 22.8% than $T_f$ of conventional positive waveform.

• 한국정밀공학회지
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• 제30권7호
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• pp.679-686
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• 2013

The reduction unit is one of the most important components in railway cars, due to the transmission of torque from the motor to the wheels. Faulty reduction gears in high-speed trains result from excessive wear on the gear or damage to the gear. These types of gear defects have a significant effect on high-speed rail operation and safety; thus, a diagnosis system for the reduction unit is needed. Vibration diagnosis technology is one of the most effective diagnostics. In this paper, the vibration parameters of a reduction unit were evaluated during a driving-gear test and a full-vehicle test, using kurtosis and the crest factor. These tests were performed under normal operating conditions; a specimen tester was used to diagnose problems in defective gears.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.604-606
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• 1992

Many Industrial applications require high facultied and high efficiency motor drives. Recently, as such motor driving system, switched reluctance motor ( S R M ) drives are proposed. This paper describes the design features, drive circuits, and performance of 6/4 S R M for high efficiency variable speed drives. The main advantages of these motors lie In high efficiency, simple driving circuitry, and low manufacturing cost. The prototypes have been built and tested, showing satisfactory performance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2156-2159
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• 2005

ADS(Address Display Period Separation) driving method has been considered to be the most appropriate driving technique for AC PDP. ADS driving method is composed of reset, address, sustain and erase period. Therefore, a long time should be allocated to an address period, which results in a reduction of brightness. To realize a high luminance and high picture quality, it is necessary to high speed addressing. However, address discharge time lag increases as the temperature decreases, which can cause the misfiring and low picture quality In this paper, the electric field effect and priming particle effect are investigated in order to reduce the address discharge time lag at low temperature. Address discharge time lag was reduced effectively when the priming particles are provided.