• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2003.10a
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• pp.345-351
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• 2003

• Proceedings of the KIEE Conference
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• 1983.07a
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• pp.208-209
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• 1983

• Geomechanics and Engineering
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• v.23 no.2
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• pp.139-149
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• 2020

Piles are widely used in structural foundations of engineering projects. However, the deformation of the soil around the pile caused by driving process has an adverse effect on adjacent existing underground buildings. Many previous studies have addressed related problems in sand and saturated clay. Nevertheless, the failure mechanism of pile driving in unsaturated soil remains scarcely reported, and this issue needs to be studied. In this study, a modeling test system based on particle image velocimetry (PIV) was developed for studying deformation characteristics of pile driving in unsaturated silt with different water contents. Meanwhile, a series of direct shear tests and soil-water characteristic curve (SWCC) tests also were conducted. The test results show that the displacement field shows an apparent squeezing effect under the pile end. The installation pressure and displacement field characteristics are sensitive to the water content. The installation pressure is the largest and the total displacement field is the smallest, for specimens compacted at water content of 11.5%. These observations can be reasonably interpreted according to the relevant unsaturated silt theory derived from SWCC tests and direct shear tests. The variation characteristics of the soil displacement field reflect the macroscopic mechanical properties of the soil around the pile.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.4 s.107
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• pp.380-386
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• 2006

Electric fuel sender fur the vehicle fuel gauge system was designed and fabricated based on the CPW(Co-Planer Waveguide) transmission line theory. It is applied on this system that characteristic impedance of RF transmission line can be varied by the surrounded material of the line. By the characteristic impedance owing the level of gasoline or diesel fuel in vehicle fuel tank, CPW line has corresponding reflected signal as much as changed impedance. Detected signal is amplified, and delivered to fuel indicator into cluster unit on dash board. Conventional floating mechanical buoy level gauge has several defects as low reliability and high break down rate by mechanical operation, and has not good linearity for the fuel level difference. CPW line with electric circuits are constructed on 1.6 mm thickness epoxy substrate, and measurement shows that this system has more accurate level and better linearity than conventional mechanical system. New electric fuel sender which has good productivity with long lifetime and low-in-cost by the SMT chip assembling could be replaced this system with conventional floating buoy system.

• Journal of Electrical Engineering and Technology
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• v.5 no.1
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• pp.116-128
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• 2010

Modeling of the three phase electric arc furnace and its voltage flicker mitigation are the purposes of this paper. For modeling of the electric arc furnace, at first, the arc is modeled by using current-voltage characteristic of a real arc. Then, the arc random characteristic has been taken into account by modulating the ac voltage via a band limited white noise. The electric arc furnace compensation with static VAr compensator, Thyristor Controlled Reactor combined with a Fixed Capacitor bank (TCR/FC), is discussed for closed loop control of the compensator. Instantaneous flicker sensation curves, before and after accomplishing compensation, are measured based on IEC standard. A new method for controlling TCR/FC compensator is proposed. This method is based on applying a predictive approach with closed loop control of the TCR/FC. In this method, by using the previous samples of the load reactive power, the future values of the load reactive power are predicted in order to consider the time delay in the compensator control. Also, in closed loop control, two different approaches are considered. The former is based on voltage regulation at the point of common coupling (PCC) and the later is based on enhancement of power factor at PCC. Finally, in order to show the effectiveness of the proposed methodology, the simulation results are provided.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.773-775
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• 2010

Diagnostic X-ray high voltage generator needs high voltage input power when operated, if electric power conditions are not suitable, could not use diagnostic X-ray high voltage generator or could not use normally by abnormal working. If diagnostic X-ray system operated with abnormally by electric power conditions, it cause of difficulty of patient diagnosis. And we used auxiliary power with battery to operate diagnostic X-ray high voltage generator without using normal electric power. We made one device after designing of new electric circuit and we compared normal power X-ray system with battery powered X-ray system by described method in this thesis. And then we found characteristic and efficiency of diagnostic X-ray high voltage generator by different input power condition.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.3
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• pp.414-417
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• 2014

At present, the demand for electric power increases, the electric power system is complicated. The size of the line-to-ground fault and the line-to-line fault occurred with complication of electric power system continue to increase, therefore several issues are raised. To address these issues effectively, the superconducting fault current limiter (SFCL) has been proposed, this study is ongoing. In this paper, we applied the SFCL in three-phase transformer and comparative analysis of the electric power burden to the SFCL. The superconductor is combined to the third winding of transformers in connection structure. In case of a third line-to-line fault, we did comparative analysis of the electric power burden to the SFCL based on the turn ratio of transformer third winding. In this case, we could confirm as the third turn ratio increased, electric power impressed to the superconducting element increased.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.4
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• pp.92-102
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• 2003

To detect electrical faults of a TFT (Thin Film Transistor) panel for the LCD (Liquid Crystal Display), techniques of converting electric field to an image are used One of them is the PDLC (polymer-dispersed liquid crystal) modulator which changes light transmittance under electric field. The advantage of PDLC modulator in the electric field detection is that it can be used without physically contacting the TFT panel surface. Specific pattern signals are applied to the data and gate electrodes of the panel to charge the pixel electrodes and the image sensor detects the change of transmittance of PDLC positioned in proximity distance above the pixel electrodes. The image represents the status of electric field reflected on the PDLC so that the characteristic of the PDLC itself plays an important role to accurately quantify the defects of TFT panel. In this paper, the image of the PDLC modulator caused by the change of electric field of the pixel electrodes on the TFT panel is acquired and how the characteristics of PDLC reflect the change of electric field to the image is analyzed. When the holding time of PDLC is short, better contrast of electric field image can be obtained by changing the instance of applying the driving voltage to the PDLC.

• Journal of the Korean Society of Safety
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• v.29 no.3
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• pp.20-27
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• 2014

Cooling equipment is the frequent occurrence of fire despite the absence of the heating element. National fire statistics in 2013 show that a total of 263 fires occurred in the cooling equipment and the number of electric fan has 145 fire cases. This is accounted for 55.1% of the whole. Electric fan is the electrical appliance that the heat is generated on the winding wire and the iron core. If such characteristic is not controled properly, fire would break out at the electric fan. also there is a gap filled with an insulator between connection terminals of the capacitor in the electric fan. But in case that the gap on the capacitor is covered with some conductive material such as dust, there would be a fire as well caused by electrical heating locally. Although many studies related with those have been conducted, electric fan fire is continuously occurred. In this study, thermal characteristics and current signal in various conditions such as the heat generation of windings including iron cores of the motor and the dielectric breakdown of terminals on the capacitor connected to the motor were detected. In order to measure the maximum temperature, "third level" wind velocity button was pushed and the time selection switch to "continuation" was set. Analyzed data would be available for the fire safety of the electric fan.

• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.42-47
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• 2014

This paper is aimed to investigate and analyze of characteristic for electrical equipment and work environment for the small-scale site. In order to investigate and analyze electrical equipment and work environment for preventing electric shock disaster in construction sites, 50 small-scale construction sites and 12 large-scale construction sites are selected. This paper completed site investigations of low-voltage equipment and the portable electric machine and equipment in 12 large-scale construction sites and 50 small-scale construction sites. The findings were about the electric shock environment relevant to the ground-relevant equipment, the panel board, the protection tools, the sockets, the temporary wiring system, the portable and movable electric machines and equipments in small-scale construction sites. Finally, this study analyzed the domestic and foreign relevant standards and regulations and these findings can be utilized as educational data warning electric shock risk caused by electric equipment in small-scale construction site.