• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.199-205
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• 2004

There are many antenna array errors. They will distort the array beam pattern and result in an increased sidelobe level. A calibration technique is proposed for correcting the antenna array errors such as mutual coupling and unequal feeder characteristics. These are modeled as a matrix representing the interaction between the radiating elements. The matrix is estimated from the measured array response vectors. The antenna array errors are corrected by modifying the beamforming weight vector. It is verified by the electromagnetic simulation and experiment that the proposed technique reduces the sidelobe level and increases the antenna gain.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.10 s.89
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• pp.938-943
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• 2004

In this paper, we propose a T-shaped DGS for CPW and provide the closed-form solutions for power loss rate, and bandwidth of the DGS. The proposed T-shaped DGS structure has a range of capacitance(C) 5.5 times wider than the dumbbell-shaped DGS structure. In addition we also analyze relations between R, L, C values of the DGS equivalent circuit and total loss rate, BW, $\omega_0$ of the DGS.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.1
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• pp.58-64
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• 2001

A microstrip patch antenna with B-WLL applications is designed and manufactured. To make a array antenna the size of patch antenna was miniaturized. A broad band is obtained by two additional parasitic elements, which are closely located to the main patch. The bandwidth of the manufactured antenna is 15% at the center frequency of 26.8 GHz. Radiation patterns are measured over a wide bandwidth.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1053-1064
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• 1999

In this paper, to transmit and receive the differently polarized signals simultaneously with a single antenna system, the dual-frequency microstrip array antenna with dual-polarization is proposed and designed. This antenna operates simultaneously at 14.25 GHz and 12.50 GHz. To extend to two dimensional array, microstrip feed line and coaxial probe through via-hole used.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1997.04a
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• pp.27-40
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• 1997

오늘날 개인용 컴퓨터의 성능 향상에 따른 고속 영상처리기용 VGA Card 의 고속화에 따라 영상신호 케이블을 통한 광대역 방사 전자파의 증가를 억제하고 , 전자파 내성시험 중 정전기 내성(IEC1000-4-2)을 갖는 영상 신호용 케이블 컨넥터의 개발에 있어 체계적인 대책이 요구되고 있다. 본 논문에서는 픽셀수에 따른 영상신호의 주파수 대역폭을 측정하여 영상처리에 장해를 주지 않는 범위에서 차단하고져 하는 주파수 대역을 정한 후, 기존 케이블의 특성임피던스를 주파수별로 구함과 동시에 일반적으로 케이블에 취부시켜 사용하고 있는 경제적인 대책에 목적을 두었으며, 기존의 케이블의 특성을 개선하기 위해 삽입되었던 대형 페라이트 비드를 소형화시켜 설계, 제작하여 영상품질을 저하시키지 않는 케이블 커넥터의 성능 평가를 실험으로 입증했다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.10
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• pp.1117-1125
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• 2007

In this paper, a study has been performed on the design of small loop probe and analysis of induced electromagnetic wave signal from a smartcard for contactless cryptographic analysis. Probes for cryptographic analysis are different from conventional EM probes, because the purpose of proposed probe is to obtain the information for secret key analysis of cryptographic system. The waveform of induced voltage on probe must be very close to radiated waveform from IC chip on smartcard because electromagnetic attack makes an attempt to analyze the radiated waveform from smartcard. In order to obtain secret key information, we need to study about cryptographic analysis using electromagnetic waves, an approximate model of source, characteristic of probe for cryptographic analysis, measurement of electromagnetic waves and calibration of probes. We measured power consumption signal on a smartcard chip and electromagnetic wave signal using proposed probe and compared with two signals of EMA point of view. We verified experimently the suitability of the proposed small loop probe for contactless cryptographic analysis by applying ARIA algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.900-912
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• 2006

A GPS receiving antenna installed in the missile's warhead is designed and fabricated at a center frequency 1.575 GHz. The circular shaped antenna is installed in the middle of the warhead where the antenna's patch and the ground plane are connected with a hollow cylindrical shaped short pin. Using the dual feeding and phase difference method, an omni-directional radiation pattern which direction is normal to the missile's axis(H-plane) is obtained. The optimized diameters of the circular patch and the cylindrical ring typed shorting pin of the GPS receiving antenna which use the FR4.material(dielectric constant $\varepsilon_r=4.6$) are 59.5 mm and 14 mm, respectively. The cylindrical body with diameter 100 mm and height 500 mm is attached to the lower part of the warhead in order to complete the missile figure. The radiation patterns are measured by changing the angle and phase between the dual feeding points. When the phase difference of dual feeding is $100^{\circ}$ and the angle between the dual feeding points is $100^{\circ}$, the nearly omni-directional radiation pattern in the H-plane is obtained. In this case, the antenna gain is -5.55 dBd and the relative level difference between the maximum and the minimum radiation intensity is 3.98 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.273-281
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• 2007

This paper presented design for a dipole antenna operated at 900 MHz band RFID tag, and antenna performance varied by the sticked material was experimentally evaluated. When dipole antenna was sticked by the material having a difffrent electric characteristic such as dielectric material, fero-magnetic material and conductor, variations of antenna return loss and radiation pattern according to the sticked material kinds, size, and height between antenna and the sticked plate were experimentally observed and evaluated. When antenna was sticked by dielectric surface, the measured return loss and radiation pattern by affection of different dielectric permittivity ratio showed resonant frequency shift of about 40 MHz and relative attenuation of 1 dB to 3 dB. Even though frequency shift by size variation of the sticked plate was observed, the measured radiation pattern of dipole antenna located on the sticked plate was similar with one without backside plate. In the case of conductor or fero-magnetic material as the sticked ground plate, because of frequency shift and phase difference by distance between dipole antenna and the sticked ground plate, amplitude decrease of radiation pattern at 910 MHz was observed about 5 dB above.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.666-670
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• 2015

This paper presents radiation pattern reconfigurable antenna for Fitbit Flex wristband which detects vital signal. Also, the paper presents Specific Absorption Rate (SAR) from the loop-dipole radiation pattern reconfigurable antenna based on the position of human body. The proposed loop-dipole radiation pattern reconfigurable antenna produces two opposite side direction radiation pattern using two RF switches. The resonant frequency of the radiation pattern reconfigurable antenna is Bluetooth communication bandwidth (2.4 - 2.485 GHz) and the maximum gain of the proposed antenna is 1.96 dBi. The proposed antenna satisfied the standard SAR value of 1.6 W/kg in 1 g tissue of the human body when the Bluetooth communication input average power of 0.04 W is excited to five parts of human body (head, chest, stomach, back, wrist). The maximum SAR value of in this simulation is presented in the part of head.

• Journal of Aerospace System Engineering
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• v.17 no.1
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• pp.68-78
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• 2023

In this paper, improvement measures were studied for false alarm (abnormal lighting) of emergency hydraulic warning light due to RF radiation signals in aircraft. When the warning lamp of the emergency hydraulic system is lit during flight due to electromagnetic interference caused by RF radiation signals, it affects flight mission and safety which can result in efficiency degradation and maintenance of flight mission. For false alarm of emergency hydraulic warning light, root cause analysis and troubleshooting were carried out. By shielding a composite strip under fuselage of the aircraft located in the path of the RF radiation signal, the RF radiation signal flowing into the emergency hydraulic indicator was blocked. Results of applying the improvement method through ground and flight monitoring were also described.