• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.1
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• pp.35-43
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• 2022

In this paper, a study was conducted to produce 20W by combining a 10W MMIC and raising the unit power amplifier to 100W SSPA by combining the 8-way spatial coupler. SSPA requires low-loss, high-efficiency coupling techniques to meet high output with the output of a single element relatively low compared to TWTA. Designed and produced in this paper, the SSPA was manufactured as a 100W SSPA by mounting eight 20W high-power amplification modules in an 8-way spatial coupler with a reflection loss of 20dB or more and an excellent coupling efficiency of 94% or more. When -10dBm was applied, it was 112.2~169.8W at 20kHz 20%, 125.9~173.8W at 400kHz 40%, 117.5~162.2W at 800kHz 40%, showing performance of over 60dB and over 100W in all three PRF conditions.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.328-332
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• 2000

본 논문에서는 기생 패치 구조와 적층 구조의 광대역 마이크로스트립 안테나에 평행 결합 선로 형태의 광대역 임피던스 정합 회로를 결합하여 쉽게 추가적인 임피던스 대역폭 개선을 얻을 수 있음을 제안하였다. 평행 결합 선로 형태의 광대역 임피던스 정합 회로 설계를 위하여 분포 회로 방식의 반복적인 방법을 제시하였고. 설계\ulcorner제작 결과 기생 패치 구조와 적층 구조에서 각각 56.23%와 16.45%의 추가적인 임피던스 대역폭 개선을 이룰 수 있었다. 그리고 방사 패턴과 측정된 이득을 보면 평행 결합 선로의 결합으로 인한 방사 패턴에서의 큰 변화는 보이지 않았고, 이득에서는 평행 결합 선로 부분의 커플링 손실로 인해 최대 이득이 약 1 dB 정도 감소하는 것을 확인할 수 있었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.286-291
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• 2011

Directional couplers are widely used in RF and microwave applications to distribute or monitor signals. This paper presented a new structure of microstrip branch line directional coupler with coupled lines. The loose couplings of microstrip branch line directional couplers are impractical for the high characteristic impedance values required for the shunt branches. To overcome this limitation, the parallel coupled lines with the shorts were used for the high characteristic impedance. The results of the simulations and measurements were presented for the proposed branch line directional coupler. Measurement of the 10 dB branch line directional coupler shows that the return loss is higher than 30 dB over 10 % bandwidth and the isolation is 35 dB or better over 8 % bandwidth.

• The Journal of the Acoustical Society of Korea
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• v.17 no.8
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• pp.34-40
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• 1998

본 논문에서는 일반 X-ray 필름을 사용하는 기존 아날로그 의료 영상 진단 체계의 문제점들을 해결하기 위해 연구 개발된 포괄적인 영상관리 전송 시스템(PACS)에서의 효율 적인 영상 전송과 저장을 위해 병원에서 매일 다량으로 발생하는 의료 영상들 중 CT와 MR영상을 대상으로 하여 새로운 무손실 영상 압축 기법인 CRAC 압축 알고리즘을 설계하 였다. CRAC 압축 알고리즘에서는 CT와 MR 영상의 파일구조를 분석하여 런랭스 코딩에 적합하도록 데이터를 재배열하는 전처리 작업을 설계하였으며, 이를 CT와 MR 영상에 최적 화 시킨 개선된 런랭스 알고리즘으로 1차 압축시켜 그 결과를 산술 부호화 알고리즘과 결합 함으로써 압축효율을 향상시켰다. 이러한 CRAC 압축 알고리즘은 무손실 압축 기법으로, 의 료 영상을 압축한 수 손실 없이 원 영상을 그대로 복원할 수 있기 때문에 PACS에서의 CT, MR 영상의 판독을 위한 단기 저장시에 적합한 압축 알고리즘으로 CT와 MR 영상의 무손 실 압축에 대해 새로운 전처리 방법을 제시하였고, 기존 무손실 압축 방법들과 비교 분석한 결과 압축률이 2.1%∼5.9% 정도 향상되었다.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1249-1251
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• 2005

YBCO CC의 초전도 전력기기 응용에 대한 자화손실 저감을 위한 연구가 진행중이다. 본 논문에서는 임계상태 모델에 기초한 수치해석을 이용하여 슬릿개수의 변화에 따른 YBCO CC의 자화손실 저감 특성을 해석하였다. 수치해석을 위한 YBCO CC의 규격은 두께와 폭이 각각 $2{\mu}m$, 4mm이며 슬릿에 의한 선재분한인 필라멘트는 각각 2,4,8개이다. 또한, 수치해석의 결과는 strip모델의 자화손실식과 비교하였다. 해석 결과, 자기적으로 결합되지 않은 strip모델 해석값과 수치해석값은 차이를 보였으며 필라멘트 개수의 변화에 따라 약 1/n 수준으로 자화손실이 저감됨을 확인하였다.

• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.228-234
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• 2002

We report theoretical investigation on the polarization selective coupling characteristics of a side-polished fiber directional coupler with a thin metal interlayer. Based on normal mode theory the coupling properties of the device under various structural conditions are analyzed. It is shown that the coupling strength between TE modes weakens rapidly with increase or metal interlayer thickness, whereas that between TM modes becomes stronger. The design conditions of the polarization splitter using the coupler to achieve high extinction ratio and low insertion loss are presented.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.12
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• pp.11-20
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• 1999

We have designed and fabricated direct-and gap-coupled microstrip hairpin-comb filters by patterning double-sided YBCO films on a single 50-mm-diameter, 0.5-mm-thick $LaAlO_3$ wafer. Both filters have a center frequency at 1.773 GHz, 12 MHz bandwidth, 0.5 dB minimum insertion loss in the passband, and very strong out-of- band rejection. Due to two attenuation poles below and above the passband, the direct-coupled hairpin-comb filter showed a better skirt characteristic than the gapcoupled hairpin-comb filter which had only one attenuation pole below the passband.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.6
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• pp.145-155
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• 2023

A radial combiner with high efficiency characteristics in the X-band was designed and manufactured using a waveguide and matching structure. In particular, in order to manufacture it in a small size, a dual waveguide to coaxial transition structure was applied that allows two ports to be matched to one waveguide. Applying this structure makes it possible to manufacture smaller than typical coaxial to waveguide radial combiner. As a result of measurement in the X-band band of 9.2~10GHz, the return loss was less than -18.408dB and the output insertion loss was less than 0.206dB, and the output combining efficiency was obtained as high as 95.37% or more. It is expected that it can be used in the combining part for high output transmitters in the millimeter wave band in the future. In particular, the range of use is expected to increase by reducing the size and weight.

• Journal of Navigation and Port Research
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• v.26 no.3
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• pp.289-294
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• 2002

The broadband high power 3-way combiner was designed and fabricated for the digital TV repeater. To achieve increase of the bandwidth and the high power capability, Wilkinson type power divider was adopted in our research. First of all, Wilkinson type power divider of equal-split and unequal-split were combined, and the characteristics of the four port in-phase power combiner was simulated for each thickness of dielectric substrates. As the results of simulation, the power combiner fabricated by using dielectric substrate of 120 mil-thickness has the characteristics as follows: insertion loss of less than -651 dB, reflection coefficient of less than -13 dB, isolation among the output ports of less than -15 dB, and pose difference among the output ports of smiler than 13$^{\circ}$. Therefore, this power combiner was possible to improve the limit of microstrip line width due to high impedance, the problem of power loss due to interaction between strip lines in a high power combiner and narrow bandwidth simultaneously. Furthermore, making broadband and high power could be achieved since the fabricated 3-way combiner has good characteristics of insertion loss, the reflection coefficient, separation between ports, and phase difference.

• Journal of the Korean Wood Science and Technology
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• v.33 no.6 s.134
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• pp.38-45
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• 2005

This research was investigated on the increase in strength capacity among different five wood-to-wood connections. Group using small diameter bolts with equal area loss has the highest increase in strength capacity, secondly the group inserted plywood, thirdly the group used glued bolt, and lastly the group inserted rubber plate. These groups showed at least 10% increase in strength capacity more than existing connection groups. Therefore, these results can be applied to develop the new highly efficient connection. To select suitable connection configuration and materials, however, economical advantage and increase in strength capacity and the difficulty should be considered by the additional works.