• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.145-147
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• 2002

In this paper, the improved fault locating method using distributed parameter which calculating the reduced voltage and current according to the ground capacitance in long transmission line was proposed. For the purpose of the fault locating algorithm non influenced source impedance, the loop method was used in the system modeling analysis. To enhance the fault locating, zero sequence of the fault current which is variable according to ground capacitance was not used but positive and negative sequence. System model was simulated using EMTP software. To verify the accuracy of proposed method, in different cases 64 sampled data per cycle was used and 160km and 300km long transmission line has fault resistance $0{\Omega}\;and\;100{\Omega}$ respectively was compared.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.233-236
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• 2000

A portable equipment that measures a current and voltage waveform of power transmission lines is pro-posed. In the equipment, the current and voltage, respectively, are detected by a loop coil and a capacitor clamped around the power lines. The detected data is transmitted by an FM wave to the receiver on the ground station. Since the receiver is isolated from the power lines, we do not require high potential insulators for the measurement of current and voltage. The proposed equipment is therefore, small-sized, light, and low in the cost of production. Experimental results presented here show that the equipment can monitor the current flowing in single wire over a ground plane and the potential of the wire.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1996-1998
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• 2000

In this paper, the electric and magnetic field waveforms produced by cloud-to-groud lightning discharges were measured and statistically analyzed. The measuring system used to measure the electric and magnetic fields is consisted of the hemisphere electric field sensor, the loop magnetic field sensor and the data acquisition system. The stepped leader is appeared before the return stroke. Some parameters of the electric and magnetic fields produced by the stooped leaders in cloud-to-ground lightning discharges were investigated.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.6
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• pp.1058-1066
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• 2011

This research paper on Tac-ELINT SW development method using M&S system describes the validation and verification methods of Tac-ELINT ground operating software development each stages, and the method of improving reusability of software using SBD(Simulation Based Design/Development) concept. In this project, We obtain the EW software SBD technologies and improved Tac-ELINT ground operating software through software crisis mitigation. This method and technology will expect to support a future EW system and any other various weapon software development.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.713-718
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• 2006

This paper concerns the measurement of thermal conductivity of grouting materials for ground loop heat exchanger. A thermal conductivity meter, QTM-500 based on modified transient hot wire method was used to measure the thermal conductivity of neat bentonite and mixtures of bentonite and various additives. Relative to the total mixture mass, as the percent additive was increased the mixture thermal conductivity increased. For the bentonite-silica sand mixtures, the higher density of the sand particles resulted in much higher mixture thermal conductivity.

• The Journal of Korea Robotics Society
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• v.19 no.1
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• pp.71-78
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• 2024

The paper presents a hardware-in-the-loop (HIL) system designed for satellite movement testing in the microgravity environment on the ground with two industrial robots. Especially, the paper deals with the contact between satellites during rendezvous and docking simulations of satellites using a robotic HILS system. For this purpose, the admittance control method plays a core role in preventing damage to the satellite or robot from contact force between satellites. The coordinate frames are transformed into the mass center of the satellite and the admittance control at the level of exponential coordinates is adopted to actively use the properties of Lie groups related to tracking errors. These methods effectively mitigate the risk of robot damage during inter-satellite contact and ensure efficient tracking performance of satellite movements.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.5
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• pp.369-374
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• 2007

Unsteady aerodynamic characteristics of the wing with flaperon flying over nonplanar ground surface are investigated using a boundary-element method. The time-stepping method is used to simulate the wake shape according to the motion of the wing and flaperon over the surface or in the channel. The aerodynamic coefficient according to the periodic motion of the flaperon is shown as the shape of loop. The rolling moment coefficient of the wing flying in the channel is same as that of the wing flying over the ground surface. The variation range of pitching moment is wider when the wing flies in the channel than over the ground surface. The present method can provide various aerodynamic derivatives to secure the stability of superhigh speed vehicle flying over nonplanar ground surface using the present method.

• Journal of Energy Engineering
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• v.13 no.4
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• pp.296-300
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• 2004

Performance evaluation and economic estimation were conducted on the water to water GSHP (Ground Source Heat Pump) installed in existing building. Ground heat exchanger was a closed vertical loop type and sized to be 5 boreholes and 100m depth per borehole. Operation efficiency of the system shows that, COP increased from 3.0 to 4.2 with entering water temperature in heating operation, however, COP decreased from 5.0 to 3.7 in cooling operation. Economic estimation was analyzed by LCC (Life Cycle Cost) method and it showed that GSHP could save 68% of cost compare to the conventional oil source. Thus, despite of the large amount of initial cost, GSHP has a economic advantage to the other energy sources.

• Journal of electromagnetic engineering and science
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• v.17 no.3
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• pp.126-132
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• 2017

In this study, we designed, measured, and analyzed a rearranged L-shape magnetic resonance coupling wireless power transfer (MR-WPT) system for practical applications with laptops. The typical four resonator MR-WPT (Tx part: source loop and Tx coil; Rx part: Rx coil and load loop) is difficult to apply to small-sized stationary and mobile applications, such as laptop computers, tablet-PCs, and smartphones, owing to the large volume of the Rx part and the spatial restrictions of the Tx and Rx coils. Therefore, an L-shape structure, which is the orthogonal arrangement of the Tx and Rx parts, is proposed for indoor environment applications, such as at an L-shaped wall or desk. The relatively large Tx part and Rx coil can be installed in the wall and the desk, respectively, while the load loop is embedded in the small stationary or mobile devices. The transfer efficiency (TE) of the proposed system was measured according to the transfer distance (TD) and the misaligned locations of the load loop. In addition, we measured the TE in the active/non-active state and monitor-open/closed state of the laptop computer. The overall highest TE of the L-shape MR-WPT was 61.43% at 45 cm TD, and the TE decreased to 27.9% in the active and monitor-open state of the laptop computer. The conductive ground plane has a much higher impact on the performance when compared to the impact of the active/non-active states. We verified the characteristics and practical benefits of the proposed L-shape MR-WPT compared to the typical MR-WPT for applications to L-shaped corners.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.8
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• pp.865-871
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• 2010

A compact dual-band(IEEE 802.11b: 2.4~2.5 GHz, 11a: 5.15~5.825 GHz) 2-channel MIMO antenna for PMP applications is presented. The proposed antenna is composed of a planar inverted F-shape antenna(PIFA) operating at 2 GHz band and a loop antenna operating at 5 GHz band. The proposed antenna is orthogonally arranged at the edge of the ground plane for polarization and pattern diversities with excellent isolation characteristics. The two PIFA antennas operating 2 GHz have connecting line($\lambda_g$/4) face to the feed point for high isolation and low correlation at 2 GHz band. The two loop antennas connected each other in the bottom side to improve the isolation at 5 GHz band. The proposed antenna has a sufficient gain in WLAN service band and is compact sized for the portable media player (PMP) applications.