• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.11
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• pp.85-92
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• 2003

In this paper, a multiple U-shaped slot antenna on 5㎓ band is designed, fabricated, and measured. The prototype consists of a U-shaped slot and two Invert U-shaped slot. To obtain wide bandwidth, the foam layer is inserted between ground plane and substrate. After various parameters, length, width, position of U-shaped slot horizontal, interval length between two invert U-shaped slot, feeding position and airgap width, optimized, a multiple U-shaped slot antenna is fabricated and measured. The measured results of the antenna are compared with its simulated results. A 2:1 VSWR impedance bandwidth of 20.4% is achiedved by employing this technique. The gain is about 5.5㏈i. The experimental far-field patterns are stable across the pass band.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.2
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• pp.41-50
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• 2010

In this paper, a multi-band antenna with novel structure for mobile communications is designed and fabricated. The proposed antenna has the Multi-band antenna characteristics by two common-grounded slots with different size and angle. In order to reduce size and to enhance the gain of the antenna, a reflector is consisted of chokes on the three sides. It is optimized by using the CST Microwave Studio commercial software based on the FIA(Finite Integration Algorithm) and PBA(Perfect Boundary Approximation), and then the fabricating and measuring is practiced. As a result of measurement, the reflection coefficient is less than -11 dB(VSWR < 1.8) and the gain of antenna is more than 6dBi at 824~894MHz and 1885-2500MHz.

• 한국정보통신설비학회:학술대회논문집
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• 2002.08a
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• pp.17-20
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• 2002

본 논문에서는 세라믹 칩 안테나를 LTCC로 구현하여 다중 대역 특성을 얻는 방법을 제안하고 있다. 휴대용 단말기에 칩 안테나를 내장함으로 물리적 손상을 피하고 위치추적 시스템(GPS) 대역과 단말기 송수신용 대역, 즉 두 대역 이상 사용 가능하고 ${\varepsilon}_r=7.8$인 세라믹 칩 안테나를 LTCC(Low Temperature Co-fired Ceramic)공정을 이용하여 세라믹 칩 내부에 정합 회로를 구현하여 이중 대역 특성을 갖는 구조에 대해 논의하고 있다. 안테나의 전체 크기는 $16mm{\times}4mm{\times}2mm$ 이며 대역폭은 삽입손실 -10dB 기준 대략 1560MHz에서 2160MHz까지 약 600MHz정도이다. 측정은 접지면의 넓이가50mmx50mm이고 두께=0.7874mm, ${\varepsilon}_r=4.6$인 FR4 기판을 이용하여 측정한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.4
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• pp.441-448
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• 2012

This paper proposes a multiband Multi-Input Multi-output(MIMO) antenna for universal serial bus(USB) dongle application. The proposed MIMO antenna consists of a modified meander strip line and inverted L stub. The two radiating elements of the MIMO antenna are symmetrically placed with respect to the center of the ground plane. The fabricated antenna satisfied a VSWR below 3 and an efficiency over 35 % in the LTE band 13, 17(704 MHz-787 MHz), DCS/PCS/WCDMA band(1.71 GHz-2.17 GHz), and LTE band 7(2.5 GHz-2.7 GHz). The envelope correlation coefficient(ECC) has below 0.45 in the LTE band 13, 17 and 0.1 in the DCS/PCS/WCDMA band and LTE band 7, respectively.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.10
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• pp.699-703
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• 1999

An experimental study to identify the energized status of the 22.9kV underground power cable by the detection of vibration has been performed. We have derived that there exists vibration at double the line frequency in live cables by electromagnetic force. The relative amplitudes of the cable vibration according to the energized status of the cable were calculated by computer simulation. The cable vibration can also be picked up by accelerometer. A prototype was tested on the underground distribution system in Chonan substation, KEPCO. Comparison between simulation results and field test results was performed. The results showed that the energized status of the calble can be identified by measuring the vibration of the cable using accelerometer.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.6
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• pp.993-999
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• 2007

This paper discusses the effects of CD type superconducting cable operation in 22.9kV multi neutral grounded distribution system during L-G fault and counterplans to power system protection. In case of using the 3-phase CD-type superconducting cable, the inductance of superconducting cable system would be decreased due to the current of shield part of superconducting cable, which is opposite direction and nearly equal value with respect to main superconductor. However, when the shield circuit system is operated in shorted state, shield current decreases faulted ground current and give effects to power system protection scheme. This study examines the phenomena of single line to ground fault case in above mentioned system using the EMTDC program and discusses the right operation method of superconducting shield.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.333-336
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• 2003

Designed transformer-less inverter for photovoltaic and small unit windturbine power system. This system consisted of boost chopper circuit of multiple-switching method and foil bridge PWM inverter. Transformer-less system was adapted to reduce cost and size. But in this system, earth-leakage current have to be considered. So, to solve this problem, we used PWM inverter switching method to reduce the earth-leakage current which flows in accordance with the variation of DC input common mode voltage.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3126-3128
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• 1999

In 22.9kV-Y overhead lines, if there is an earth fault, high fault current causes surge type over-voltages around this place. There are generally two types of earth faults. One is an earth fault which occurs when a voltage line falls to earth line. The other occurs when a voltage line directly falls to the earth. This study presents an analysis method on the earth fault.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1738-1740
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• 2003

This paper deals with the characteristic analysis of multi-grounding system. In order to assess the effectiveness of bonding two grounding systems, the scale model grounding simulation system and grid grounding conductors which were downsized as a scale factor of 100:1 were designed and fabricated. A profile of GPR(Grounding Potential Rise) of each case was measured. Also the measured results were compared with the analysis results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.407-412
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• 2004

Designed transformer-less inverter for photovoltaic and small unit windturbine power system. This system consisted of boost chopper circuit of multiple-switching method and full bridge PWM inverter. Transformer-less system was adapted to reduce cost and size. But in this system, earth-leakage current have to be considered. So, to solve this problem, we used PWM inverter switching method to reduce the earth-leakage current which flows in accordance with the variation of DC input common mode voltage.