• Transactions on Electrical and Electronic Materials
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• 제8권4호
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• pp.166-169
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• 2007

In applying LCD to TV application, one of the most significant factors to be improved is image sticking on the moving picture. LCD is different from CRT in the sense that it's continuous passive device, which holds images in entire frame period, while impulse type device generate image in very short time. To reduce image sticking problem related to hold type display mode, we made an experiment to drive TN-LCD like CRT. We made articulate images by turn on-off backlight, and we realized the ratio of Back Light on-off time by counting between on time and off time for video signal input during 1 frame (16.7 ms). Conventional CCFL (cold cathode fluorescent lamp) cannot follow fast on-off speed, so we evaluated new fluorescent substances of light source to improve residual light characteristic of CCFL. We realized articulate image generation similar to CRT by CCFL blinking drive and TN-LCD overdriving. As a result, reduced image sticking phenomenon was validated by naked eye and response time measurement.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2427-2429
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• 2005

OLED in the spotlight of display market has advantages of low power driving, self-emission and fast response. But it has disadvantages of inefficient luminescence and high power consumption. Most of PM(passive Matrix) DC-DC converters in common use is using voltage divider. This voltage divider type has some difficulties of suitable electric device selection for voltage division and of the stabilized output due to feedback current trimming. Therefore, noise analysis and power solution in OLED are important technologies having an effect on electric characteristics. In this dissertation, we have obtained the stable output by using digital signals in multi-channel DC-DC converter, the profit of power consumption reduction of driving source and economical efficiency in the PCB board size.

• 대한교통학회지
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• 제22권6호
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• pp.145-157
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• 2004

끼어들기 행태는 차로변경 대상 측면차로에 충분한 차간간격이 존재하지 않는 상황에서도 운전자가 강제적으로 차간간격을 만들어내는 적극적인 운행행태이다. 이러한 끼어들기는 주변 주행차량들의 움직임에 종속적으로 대응하지 않는 능동적인 운행행태로 간격수락이론이 주요 기반을 이루는 기존 차로변경보형으로는 설명되지 않는다. 보다 현실적인 교통류 흐름의 모사를 지원하기 위하여 끼어들기 행태를 설명하는 운전자 운행행태 모형 개발이 수반될 필요가 있다. 본 연구에서는 합류부와 분류부를 대상으로 끼어들기 특성 분석 및 분포 추출을 하였으며, 끼어들기 판단지표를 도출하여 모형을 개발하였다. 합류부와 분류부를 대상으로 차로변경행태 분석 결과 차간시간의 경우 차로변경차량과 차로변경 종료차로 선두차량과의 차간시간은 E기뭏(0.343, 3) 분포, 후미차량과의 차간시간은 Weibull(1.12, 1.81) 분포, 상대속도의 경우 차로변경차량과 차로변경 종료차로 선두차량과의 상대속도는 Lognormal (11.8, 4.6) 분포, 후미차량과의 상대속도는 Lognormal (6.01, 4.27) 분포, 차로변경차량의 가속 분포는 Lognormal (1.24, 2.5) 분포, 감속 분포는 Normal(-1.51, 1.27) 분포를 따르는 것으로 분석되었다. 현장관측 자료를 토대로 끼어들기 판단지표 도출 결과 감속하는 차로변경 종료차로 후미차량의 속도 분포가 평균값 6.78m/sec, 분산 9.84m/sec인 Gamma(2.74, 1.74)분포를 따르며, 현장관측 자료의 분포와 모형결과 분포의 동일성 여부를 판단하기 위해 신뢰수준 95%로 $x^2$-test 검정을 실시 한 결과 "모형결과 분포는 현장관측 자료의 분포를 따른다."고 검증되었다.

• 한국자동차공학회논문집
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• 제13권4호
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• pp.152-159
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• 2005

The method of induction noise reduction can be classified by using passive control or active control method. However, the passive control method has a demerit to reduce the effect of noise reduction to low frequency (below) 500Hz) range and to be limited in a space of the engine room. Whereas, the active control method can overcome the demerit of passive control method. The algorithm of active control is mostly used in LMS (Least-Mean-Square) algorithm because it can obtain the complex transfer function easily in real-time. Especially, Filtered-X LMS (FXLMS) algorithm is applied to an ANC system. However, the convergence performance of LMS algorithm could not match if the FXLMS algorithm is applied to an active control of the induction noise under rapidly accelerated driving conditions. So, in order to solve the problem in this study, the Moving Bandpass Filter(MBPF) was proposed and implemented. The ANC using MBPF for the reduction of the induction noise shows that more noise reduction as 4dB than without MBPF.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.551-554
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• 2005

The method of the reduction of the automotive induction noise can be classified by the method of passive control and the method of active control. However, the passive control method has a demerit to reduce the effect of noise reduction at low frequency (below 500Hz) range and to be limited by a space of the engine room. Whereas, the active control method can overcome the demerit of passive control method. The algorithm of active control is mostly used the LMS (Least-Mean-Square) algorithm because the LMS algorithm can easily obtain the complex transfer function in real-time. Especially, When the Filtered-X LMS (FXLMS) algorithm is applied to an ANC system. However, the convergence performance of LMS algorithm goes bad when the FXLMS algorithm is applied to an active control of the induction noise under rapidly accelerated driving conditions. Thus Normalized FXLMS algorithm was developed to improve the control performance under the rapid acceleration. The advantage of Normalized FXLMS algorithm is that the step size is no longer constant. Instead, it varies with time. But there is one additional practical difficulty that can arise when a nonstationary input is used. If the input is zero for consecutive samples, then the step size becomes unbounded. So, in order to solve this problem. the Correlation FXLMS algorithm was developed. The Correlation FXLMS algorithm is realized by using an estimate of the cross correlation between the adaptation error and the filtered input signal to control the step size. In this paper, the performance of the Correlation FXLMS Is presented in comparison with that of the other FXLMS algorithms based on computer simulations.

• Journal of Power Electronics
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• 제14권2호
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• pp.257-264
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• 2014

A novel converter-free AC LED driver that is highly resistant to the fluctuation of AC voltage is proposed in this study. By removing large passive components, such as the bulky capacitor and the large-value inductor, the integration of the driver circuit is enhanced while the driving current remains stable. The proposed circuit provides LED lamps with a driving current that can follow the sinusoid waveform to obtain a very high power factor (PF) and low total harmonic distortion (THD). The LED input current produced by this driving current is insensitive to fluctuations in the AC voltage. Users will thus not feel that LED lamps are flashing during the fluctuation. Experiment results indicate that the proposed system can obtain PF of 0.999 and THD as low as 3.3% for a five-string 6 W LED load under 220 V at 50 Hz.

• 한국정밀공학회지
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• 제29권2호
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• pp.178-184
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• 2012

This paper presents a transformable track mechanism for wall climbing robots. The proposed mechanism allows a wall climbing robot to go over obstacles by transforming the track shape, and also increases contact area between track and wall surface for safe attachment. The track mechanism is realized using a timing belt track with one driving actuator. The inner frame of the track consists of serially connected 5R-joints and 1P-joint, and all joints of the inner frame are passively operated by springs, so the mechanism does not require any actuators and complex control algorithms to change its shape. Static analysis is carried out to determine design parameters which enable $90^{\circ}$ wall-to-wall transition and driving over projected obstacles on wall surfaces. A Prototype is manufactured using the transformable track on which polymer magnets are installed for adhesion force. The size of the prototype is $628mm{\times}200mm{\times}150mm$ ($Length{\times}Width{\times}Height$) and weight is 4kgf. Experiments are performed to verify its climbing capability focusing on $90^{\circ}$ wall to wall transition and driving over projected obstacle.

• 대한교통학회지
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• 제33권6호
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• pp.509-519
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• 2015

최근 사업용운전자들의 음주운전이 증가하고 있다. 본 연구는 사업용운전자들의 음주문제행동에 영향을 미치는 요인으로 스트레스 대처방식을 상정하고 스트레스 대처방식이 생활스트레스를 증가시켜 음주문제행동에 영향을 주는지를 알아보고자 하였다. 총 1308명의 사업용운전자들이 연구에 참여하였다. 연구결과, 사업용운전자들의 스트레스 대처방식으로 문제해결, 조력추구, 정서적 완화, 소망적 사고, 수동적 회피 5개 방식이 확인되었으며, 이 중 문제해결, 소망적 사고, 수동적 회피 대처방식에서만 생활스트레스의 매개효과가 관찰되었다. 즉 문제해결 전략을 적게 사용할수록, 소망적 사고와 수동적 회피 전략을 많이 사용할수록 생활스트레스는 높았으며, 이것은 다시 음주문제행동을 높이는 것으로 나타났다. 이러한 결과는 스트레스 대처방식에 대한 운전자 교육의 필요성을 시사하고 있다.

• 대한전자공학회논문지
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• 제25권5호
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• pp.509-521
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• 1988

In the designs of integrated circuits, the buffer circuits used for driving a large capacitive load from minimum-structured logic circuit outputs have important effects upon system throughputs. Therefore it is important to optimize the buffer circuits. In this paper, the principle of designing CMOS buffer circuits which have the minimum delay and drive the given capacitive load is discussed. That is, the effects of load capacitance upon rise time, fall time, and delay of the CMOS inverter and the effects of parasitic capacitances are finely analysed to calculate the requested minimum-delay CMOS buffer condition. This is different from the method by C.A. Mead et. al.[2.3.4.]which deals with passive-load-nMOS buffers. Large channel width MOS transistor stages are necessary to drive a large capacitive load. The effects of polysilicon gate resistances of such large stages upon delay are also analysed.And, the area of buffer circuits designed by the proposed method is smaller than that of buffer circuits designed by C.A. Mead's method.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권4호
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• pp.155-159
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• 2004

This work reports the theoretical and experimental investigations of capillary bust valves to regulate liquid flow in microchannels. The theoretical analysis uses the Young-Laplace equation and geometrical considerations to predict the pressure at the edge of the valve opening. Numerical simulations are employed to calculate the meniscus shape evolution while the interface is pinned at the valve edge. Microchannels and valves are fabricated using soft lithography. A wafer-rotating system, which can adjust the driving pressure by rotational speed, induces a liquid flow. Experimentally measured valve-bursting pressure agrees with theoretical predictions.