• Journal of the Korean Institute of Telematics and Electronics
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• v.6 no.1
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• pp.57-59
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• 1969

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.12
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• pp.1460-1466
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• 2010

In this paper, we analyzed the performance of radar target classification using the monostatic and bistatic radar cross section(RCS) for four different wire targets. Short time Fourier transform(STFT) and continuous wavelet transform (CWT) were used for feature extraction from the monostatic RCS and the bistatic RCS of each target, and a multi-layered perceptron(MLP) neural network was used as a classifier. Results show that CWT yields better performance than STFT for both the monostatic RCS and the bistatic RCS. And, when STFT was used, the performance of the bistatic RCS was slightly better than that of the monostatic RCS. However, when CWT was used, the performance of the monostatic RCS was slightly better than that of the bistatic RCS. Resultingly, it is proven that bistatic RCS is a good cadndidate for application to radar target classification in combination with a monostatic RCS.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.4
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• pp.451-458
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• 2014

This paper introduces a bistatic ISAR imaging technique. In bistatic geometry, the transmitter and receiver are placed in different locations. The monostatic ISAR is inadequate not only for obtaining images on targets approaching along the radar's line of sight, but also for stealth targets. In this paper, geometry, signal modeling as well as bistatic Doppler for bistatic ISAR are introduced to address these problems. Simulations results show bistatic ISAR images as well as monostatic ISAR images against target's moving scenarios, and analyze their differences for each scenario.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.11
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• pp.69-76
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• 2010

From the present paper we researched about the design of 4-Way Wilkinson divider with waveguide to stripline transition which used to split the LO signal with equi-amplitude and equi-phase in the X-Band Monopulse radar RF front-end. The monopulse radar front end operating in the X-Band is composed of 3 waveguide reception mixers which down convert sum, azimuth and elevation signal to IF and one SSB waveguide mixers which generate X-Band test signal. It is required the 4-way divider with low loss, equi amplitude and equiphase splitting the LO signal to provide the LO signal to each mixer consisting RF frontend. In this paper we designed and fabricated the 4-Way Wilkinson divider with waveguide transition to divide the LO signal into equi-amplitude and equi-phase. The fabricated Wilkinson divider have the insertion loss 6.8dB, VSWR 1.06~1.28, and phase balance maximum 4.5degree for each output ports.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.902-905
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• 2009

축사 또는 쓰레기장에서 에서 발생되는 있는 물질인 암모니아, 아민, 메탄, 탄화수소류 등에 대한 처리를 위한 촉매 개발을 수행하였다. 암모니아를 금속산화물형태의 촉매를 사용하여 산화하였을 경우 $N_2$, NO, $NO_2$, $N_2O$가 일정 비율로 생성되게 된다. 이때의 NO, $NO_2$는 악취는 발생하지 않으나 유독성 가스이므로 이에 대한 선택성이 낮은 촉매를 선별하고 온도에 따른 활성능을 시험하여 최적의 촉매조성을 도출하였다. 다양한 산화가를 지닌 망간을 대상으로 각종 조촉매의 혼합에 따른 실험을 수행하여 최적 조성을 도출 하였다. 촉매 선별작업에서는 충전층을 사용하고, 선별된 촉매에 대하여 모노리스에 코팅하여 사용할 수 있는 모노리스형태의 반응기를 장착하여 모노리스 형태 촉매의 반응성 및 피독특성을 실험하였다.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.159-161
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• 2005

본 논문은 회전형 대용량의 진단 X-선 발생장치를 모노 블록 형태로 설계, 병원의 모바일 진단장치나, 산업용 X-선 장치로의 적용이 가능한 16kw급 X-선 발생장치에 관한 연구이다. 본 장치는 X-선 발생을 위한 고전압 발생부에 회전형 Anode 형의 X-선관을 사용하였고, X-선관의 로터를 구동할 수 있는 로터 구동회로를 추가 하였다. 고주파 고전압용 인버터에는 IGBT(600/300A)를 100kHz로 고주파 스위칭 함으로서 고전압 변압기를 비롯한 고전압 발생부의 크기와 무게를 최소화하였다. 또한, 기존의 16kw급 대용량 진단 X-선 발생장치를 X-선관과 고전압부를 일체화한 모노블록 형태로 설계, 제작하여 부하변동에 따른 X-선 관전압과 관전류의 동작특성을 실험을 통하여 입증하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.6
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• pp.495-503
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• 2016

This paper proposes the design of multiband repeater antenna with fire-fighting band for in-building mobile communication. The proposed antenna is composed of a center monopole and 4 parasitic elements on a circular plate. In order to realize good reflection coefficients at the multiband, mutual coupling between 4 parasitic elements and center monopole antenna is considered. The important parameters such as distance between parasitic element and a center monopole, and each height of a center monopole and 4 parasitic elements are simulated to obtain good antenna characteristics at the multiband. The diameter of 4 parasitic elements and a center monopole was fixed to 10 mm for easy design and manufacturing. The measurement results of reflection coefficients, 2-D patterns and gain agreed well with their simulation ones.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.1
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• pp.121-126
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• 2022

This study is about an antenna implemented in the form of a monopole having a hexagonal symmetric pattern by simplifying the modified Hilbert curve fractal monopole structure. The modified Hilbert curve fractal monopole structure was simplified and miniaturized, and the radiator was implemented in a hexagonal symmetrical pattern to improve performance. The dielectric constant of substrate is 4.7, and the total line length with a meander-shaped symmetrical structure is 59 mm. The size of the antenna is 10 mm × 10 mm × 0.8 mm, and the line width is 0.4 mm. The size of the antenna measuring jig is 64 mm × 21 mm × 1 mm. The resonant frequency is 1.57 GHz, and the frequency range is 1.51 to 1.615 GHz. The frequency bandwidth is 105 MHz. As for the antenna gain, the measurement gain of the YZ-plane was 2.32 dBi, and that of the XZ-plane was -1.03 dBi. As a result, we confirmed that antenna miniaturization is possible using a hexagonal symmetric pattern fractal structure. In addition, we confirmed that the antenna performance can be easily improved by changing the structure of the radiator.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.8A
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• pp.1417-1427
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• 2001

본 논문에서는 밀리미터파를 이용하여 사용자에게 양방향 무선 멀티미디어의 구현을 가능케 하는 LMDS 송수신 모듈을 설계, 구현하였다. 제작된 LMDS 송수신 모듈은 신서사이져, 혼합기, 저잡음 증폭기, 고출력 증폭기, 듀플렉서 등으로 구성하였으며, 전체적으로는 전원부와 제어부를 통하여 이상여부를 감시하며, 송수신 모듈에 이상이 발생했을 때 이를 보호할 수 있도록 구현하였다. 여기서 DAVIC 표준에 맞도록 IF부 대역은 0.95∼1.45GHz의 500MHz 대역폭에서 동작하도록 제작하였고, 상하향 혼합기는 격리도 특성을 최대화하였으며, 이를 위해 하이브리드 링형을 이용한 다이오드 평형 구조를 적용하여 설계하였다. 혼합기로 주입되는 Local 주파수는 안정도가 높아야 함으로 유전체 공진형 발진기로 구현하였다. 또한 저잡음 증폭기와 고출력 증폭기는 정보통신부에서 공고한 3사 주파수 대역을 모두 수용할 수 있도록 24GHz∼26.5GHz의 대역에서 정상적인 동작을 할 수 있도록 설계하였으며, 특히 저잡음 증폭기는 잡음 환경에서 작은 신호를 손실 없이 얻을 수 있도록 잡음지수를 최소화하고, 30dB 이상의 충분한 이득이 구현되도록 하였다. 고출력 증폭기는 15dBm 이상의 출력을 송신하면서도 선형성에 문제가 없도록 혼변조왜곡(IMD) 특성을 고려하여 설계하였다. 그리고 듀플렉서는 우수한 주파수 선택도와 낮은 삽입손실 특성을 갖도록 송수신 필터 모두 5개의 공진기를 포함한 Chebyshev형 구조를 갖으며 생산성이 뛰어난 모노리딕형으로 구현하여, LMDS 송수신 성능을 구현하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.3
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• pp.261-268
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• 2016

In this paper, dual-polarized monopulse cassegrain antenna for W-band millimeter-wave seeker was proposed and the performances were verified by the measured results of the fabricated antenna. Dual-polarized monopulse Cassegrain antenna consists of main/subreflector, dual-polarized feed horn and monopulse comparator. The proposed feed horn has $2{\times}2$ array square waveguide feeding structure to make monopulse signals and it was designed using 90 degree rotational symmetric structure to receive dual-polarized signals. At the sum and difference channel, the measured vertical and horizontal polarization radiation pattern were similar. Measurement gains are 35.1 dBi for v-pol. and 35.6 dBi for h-pol. at the center frequency with 0.5dBi difference between each polarization and the side lobe level is below -21.6 dB.