• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.223-234
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• 1993

The main characteristics of PHC piles is that silica material and autoclave curing technique are used when manufacturing to have higher strength than PC piles. In this paper, pile drivability and bearing capacity characteristics of the PHC piles are studied through numerical analysis based on wave propagation theory, driving records and pile load tests in situ. It is found that we can have higher bearing capacity by using the PHC piles rather than the PC on condition that the most effective driving equipment is chosen when driving the pile. In other words, since the PHC piles have higher resistance to driving energy, the heavier ram can be used in the driving process, which results in the higher bearing capacity.

• Journal of Power Electronics
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• v.9 no.2
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• pp.164-172
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• 2009

Recently, 2-dimensional flat light sources have been attracting much attention for its use in LCD backlight applications because of its high luminous efficiency and uniformity. A long-gap discharge, mercury-tree flat fluorescent lamp has been developed, which shows a high brightness ($>5000\;cd/m^2$) and high luminous efficacy (60 lm/W). Additionally, it has a wide operating margin and stable driving condition with the aid of an auxiliary electrode. For driving the lamp, a narrow pulse power to maintain the glow discharge state is required. Since there has been no research for this kind of lamp driving, this paper proposes a newly developed short-pulse, high-voltage lamp-driving scheme. The proposed lamp system uses a ballast with a coupled-inductor in order to raise the short pulse voltage up to the lamp ignition level and to obtain energy-recovery action during the glow discharge mode. The operation principles are presented and also the system performances such as the lighting efficiency, spatial and angular uniformities are evaluated by hardware experiments. The results show that the proposed lighting system is a good candidate for the next-generation of LCD backlight systems.

• Journal of Sensor Science and Technology
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• v.21 no.3
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• pp.198-203
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• 2012

In this paper, the driving information system of the bicycle has been studied by using the 3-axis acceleration sensor. The sensor module composed of 3-axis acceleration sensor and MCU(Microcontroller Unit) was mounted onto the handle of bicycle and the experiments were conducted on the flatland, uphill and downhill of bicycle road. Three axis acceleration values were converted to the pitch and roll angles, then four major compensation methods have been applied to achieve meaningful data for driving information system. The experimental results of pitch angles showed 2.46, -1.26, 7.79 degrees in case of flatland, uphill, downhill, respectively. When the steering handle turned to the left direction, roll angles showed -29.35, -41.67, -36.98 degrees at each road condition. With the right-turn, roll angles presented 20.05, 33.75, 24.44 degrees in case of flatland, uphill, and downhill, respectively. The pitch angle has been increased more than 40 degrees at stop mode. By using the change of pitch and roll angles, we could obtain the driving information system of bicycle successfully.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1778-1784
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• 2010

This study investigates the criteria for assessing the vibration serviceability of highway bridges using advanced driving simulator. Reiher-Meister Curves were firstly reviewed for extended application to serviceability of highway bridges. Modified Reiher-Meister Curves were provided in this paper based on field test results and numerical analyses results. The Modified Reiher-Meister Curves were evaluated using advanced driving simulator. The new curve consisted of 4 level, A(Disturbing), B(Strongly perceptible), C(Allowable), and D(Comfortable). The new criteria will be extensively applied to design and maintain highway bridges with respect to driver condition.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.234-240
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• 2003

This study aims to investigate dynamic properties of express buses in the very low frequencies which affect motion sickness incidence. Since passengers often use express buses for long distance traveling, it is a critical point whether a give rise to motion sickness or not. In the study accelerations at the three points on the floor of the six test vehicles were measured during the driving at constant speeds. By applying frequency weighting curves suggested in ISO 2631-1 and ISO 2631-3, physical amount of accelerations were changed into perceptual amount which determines incidence of motion sickness. Motion sickness dose values were calculated from the frequency weighted time history of accelerations, and compared between the vehicles, driving conditions, and the seat positions in the bus. During the driving on public road and high ways for 50 minutes vomiting incidence ratios ranged 0.4 to 0.8%, which were equivalent to 2.4 to 4.8% for 5 hours' driving. The value of 4.8 % means two among 45 passengers may vomit after the traveling, which is very serious situation. Considering the very smooth driving condition at which the data were collected, motion sickness dose values will increase in real situations

• Journal of Korean Port Research
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• v.14 no.3
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• pp.303-312
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• 2000

In this paper, we describe an image processing algorithm which is able to recognize the road lane. This algorithm performs to recognize the interrelation between AGV and the other vehicle. We experimented on AGV driving test with color CCD camera which is setup on the top of vehicle and acquires the digital signal. This paper is composed of two parts. One is image preprocessing part to measure the condition of the condition of the lane and vehicle. This finds the information of lines using RGB ratio cutting algorithm, the edge detection and Hough transform. The other obtains the situation of other vehicles using the image processing and viewport. At first, 2 dimension image information derived from vision sensor is interpreted to the 3 dimension information by the angle and position of the CCD camera. Through these processes, if vehicle knows the driving conditions which are lane angle, distance error and real position of other vehicles, we should calculate the reference steering angle.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.165-168
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• 2007

Electrooptic characteristics of Xe-type flat fluorescent lamps (FFL) have been investigated by using a Q-V Lissajous method. It was found that the luminance of the Mgo-coated FFL became more than doubled compared to normal FFLs operated at the same driving voltage, indicating the possibility of the efficacy improvement in the MgO-coated FFLs. Change in the driving condition, in particular, the duty ratio had effects on the electrooptic properties, and it was found that the duty ratio of 50% was the optimum condition from the viewpoints of the efficacy and the lamp voltage.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.2
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• pp.437-443
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• 1998

Automobile company tries to reduce the inertia of powertrain to increase the fuel efficiency and increase the engine power every year to make the high speed driving possible at full load condition. These cause the torsional vibration of powertrain. But the demand about ride comfort improvement is increased constantly, so torsional vibration of powertrain become an emergency problem to be cured. This study is a basic research to reduce the torsional vibration of powertrain at driving condition. First, the heavy duty powertrain is characterized as a vibrating system. Its natural frequencies and mode shapes are reviewed. Second, by comparison of simulation results and experiment results, validity of developed model is verified. Finally, the couterplan which can reduce the torsional vibration by mode analysis and parameter modification is suggested.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1660-1663
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• 2005

Unwanted vibrations are inevitably induced in other directions when pure unidirectional vibration motion is desired for the vertical scratching mechanism. Pure vertical vibration motion of the scratching machine can be obtained by driving identical two motors with symmetrically positioned eccentric unbalance masses. The desired optimal condition for driving pure vertical vibration for the scratching machine is assumed to be the resonance condition in that direction. Imposing the flexibility of the scratching machine in the horizontal direction, we can find out the amount of horizontal vibration component while maintaining the resonance in vertical direction. The desired stiffness in horizontal direction which produces the minimum vibration in horizontal direction are defined which can be used as a guide line to design the supporting structure of the scratching machine.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.479-482
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• 2007

This paper presents experimental analysis of a friction-driven wheel responsible for generating wheel squeal. Creep and squeal noise generating mechanism are influenced by friction conditions of attack angle, loading force, driving velocity and surface roughness. Squeal noise phenomena has been examined under the laboratory condition by the model rig. Creep characteristics and squeal noise were observed by varying relative velocity of the wheel with respect to the rail and friction coefficient.