• Proceedings of the ESK Conference
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• 1995.04a
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• pp.165-172
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• 1995

Twenty six subject drove screws with a screw driver into thick wooden sheet at three vertical and horizontal locations. Subjects drive screws for 3 minutes at each location and they assessed the conditon using the psychophysical scale. An ANOVA showed that only vertical location was a signicant factor in determining the pain ratings of various body parts. Driving screws at elbow height on the vertical surface ans with the lower arm close to the body on the horizontal surface were the work locations with the smallest ratings of perceived pain and discomfort. Wearing gloves had significant effects on reducing the pain of the hand.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1661-1668
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• 2016

A fixed off-time controlled high power factor ac-dc LED driver is proposed in this paper, which employs a novel zero-crossing-compensation (ZCC) circuit based on a fixed off-time controlled scheme. Due to the parasitic parameters of the system, the practical waveforms have a dead region. By detecting the zero-crossing boundary, the proposed ZCC circuit compensates the control signal VCOMP within the dead region, and is invalid above this region. With further optimization of the parameters KR and Kτ of the ZCC circuit, the dead zone can be eliminated and lower THD is achieved. Finally, the chip is implemented in HHNEC 0.5μm 5V/40V HVCMOS process, and a prototype circuit, delivering 7~12W of power to several 3-W LED loads, is tested under AC input voltage ranging from 85V to 265V. The test results indicate that the average total harmonic distortion (THD) of the entire system is approximately 10%, with a minimum of 5.5%, and that the power factor is above 0.955, with a maximum of 0.999.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.522-523
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• 2008

This paper presents an LED lighting which can control its color temperature. It consists of a power factor correction (PFC) circuit, an LED driver, and an LED color control circuit. The proposed system can adjusts the light intensity to obtain a desired color with independently changeable illuminance. The power factor of the PFC circuit is 98%. The LED driver has 90% efficiency at 300mA output current. The output power of the experimented LED lighting is 150 W. The achieved color temperature range was from 3000K to 7500K, and the illumination one was from 500 lux to 1500 lux.

• Proceedings of the ESK Conference
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• 1997.10a
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• pp.260-266
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• 1997

The Navigation Streets Map that directly supplies information for a driver plays an important role in Car Navigation System(CNS). Therefore, cause the compatibility, preference, visibility, and readability of the navigation streets map will be hold sway over driver's information acquisition, safety, and performance in CNS, it is important that designer's requirements should be analyuzed for ergonomic design of navigation streets map. Especially, there are differences between the topographical objects marking method and that of the general map in a navigation streets map. Because much information is marked in a narrow space, it is important that the text information should be done in navigation streets map. Also, because it is a important factor to mark the text format for the marking method of the topographical objects, the design requirements will be drawn out through the factor analysis for the text marking method. And when ergonomic designers are doing, this result will be basic research for developing driving simulator of CNS and it will be a ergonomic guideline of navigation streets map.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.127-135
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• 2009

Most traffic information that drivers receive while driving are stored in their short-term memory and disappear within a few seconds. Contemporary modeling approaches using a dummy variable can't fully explain this phenomenon. As such, this study proposes to use utility functions of real-time in-vehicle traffic safety information (IVTSI), analyzing its safety impacts based on empirical data from an on-site driving experiment at signalized intersection approach with a limited visibility. For this, a driving stability evaluation model is developed based on driver's driving speed choice, applying an ordered probit model. To estimate the specified utility functions, the model simultaneously accounts for various factors, such as traffic operation, geometry, road environment, and driver's characteristics. The results show three significant facts. First, a normal density function (exponential function) is appropriate to explain the utility of IVTSI proposed under study over time. Second, the IVTSI remains in driver's short-term memory for up to nearly 22 second after provision, decreasing over time. Three, IVTSI provision appears more important than the geometry factor but less than the traffic operation factor.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.48
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• pp.145-152
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• 1998

Driving performance is characterized by many things such as driver's experience period, age, ability of information processing and reaction time of control devices and so forth. However, each factor of driving performance is needed to help and screen a poor driver for safe driving. In this paper, driving performance was estimated by reaction of manipulating brake, accelerator, steering wheel and speed. Subjects were grouped by experience of accident and age. Combinations of every group were analysed. For all the dependent variables, only steering wheel and speed were shown to have significant difference, which could be regarded as visual information of speed and direction were the important factors to drive safely. Especially for tile elderly, it is needed to enhance their ability of visual information processing that is to be decreased with aging. Therefore driving simulator to train and screen the poor driver should be studied.

• Journal of Power Electronics
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• v.14 no.4
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• pp.632-640
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• 2014

For low-power high-frequency LED driver applications in small form factor mobile products, a high-efficiency boundary conduction mode tapped-inductor boost converter is proposed. In the proposed converter, the switch and the diode achieve soft-switching, the diode reverse-recovery is alleviated, and the switching frequency is very insensitive to output voltage variations. The circuit is quantitatively characterized, and the design guidelines are presented. Experimental results from an LED backlight driver prototype for a 14 inch notebook computer are also presented.

• Journal of Power Electronics
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• v.18 no.2
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• pp.640-650
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• 2018

A TRIAC dimmable LED driver with a wide tuning range and a two-stage uniform dimming scheme is proposed in this paper. To solve the restricted dimming range problem caused by the limited conduction ratio of TRIAC dimmers, a conduction ratio compensation technique is introduced, which can increase the output current up to the rated output current when the TRIAC dimmer turns to the maximum conduction ratio. For further optimization, a two-stage uniform dimming diagram with a rapid dimming curve and a slow dimming curve is designed to make the LED driver regulated visually uniform in the whole adjustable range of the TRIAC dimmer. The proposed control chip is fabricated in a TSMC $0.35{\mu}m$ 5V/650V CMOS/LDMOS process, and verified on a 21V/500mA circuit prototype. The test results show that, in the 90V/60Hz~132V/60Hz ac input range, the voltage linear regulation is 2.6%, the power factor is 99.5% and the efficiency is 83%. Moreover, in the dimming mode, the dimming rate is less than 1% when the maximum dimming current is 516mA and the minimum dimming current is only about 5mA.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.2
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• pp.282-289
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• 2008

To improve the efficiency of PDP TV, it should minimize the power losses transpired during AC-to-DC power conversion and PDP driving process. Generally the input power supply for PDP driving employes a two-stage power factor corrected converter, and it needs additional DC-to-DC converters to supply driving power for reset circuit ed sustain driver, which has high power consumption. However, such a circuit configuration has a difficulty for the PDP market requires low cost. To alleviate this problem, a new circuit composition is presented. It integrates input power supply with reset and sustain driver in a single power stack The input power supply of the proposed circuit has a single-stage structure to minimize power conversion loss, and it directly supplies power to the sustain driver so as to reduce the system size and cost.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.372-375
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• 2008

Drivers need to process dynamic stimulus in real - time with full attention from Telematics environment. However, as the information technology revolution brings more and more data into vehicles, all of it competing for the drivers' attention, the development of automated assistance for driver information processing becomes increasingly import ant. There for e, drivers' workload is very essential factor for safety driving in Telematics environment. In this paper, we have discussed driver distraction caused by driver conversation while driving and proposed voice activity detection algorithm for measuring driver workload. Finally, we show how voice activity detection system works for measuring driver workload.