• E2M - 전기 전자와 첨단 소재
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• 제9권9호
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• pp.969-977
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• 1996

본고에서는 여러가지 Wide Band-gap중에서 특히 최근에 많은 관심을 끌고 있는 GaN와 4H-SiC, 6H0SiC의 전자기적 물성을 소개하고 현재 이들로부터 제작된 prototype소자들의 성능을 비교함으로써 그 발전현황을 알아보기로 한다. 본고에서 관심을 두는 소자분야는 광전소자(optoelectronic devices)라기보다는 고주파 고출력용 전력소자임을 밝힌다. 아울러 GaN로부터 제작된 MESFET(MEtal Semiconductor Field-Effect Transistor)소자의 고주파 대역에서의 Large-Signal특성을 Device/Circuit Model을 통하여 실험치와 비교하여보고 이로부터 최적화된 channel 구조를 갖는 소자구조에서의 RF특성을 조사한다.

• 한국전자파학회논문지
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• 제18권4호
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• pp.358-363
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• 2007

본 논문에서는 휴대 방송용 기기에 적합한 다중 대역 및 광대역 안테나를 제안한다. 제안된 안테나는 두 복사체의 공진 주파수를 인접시킴으로써 DVB-H 서비스 대역에서의 광대역 특성을 만족시키고, 체배 주파수를 이용하여 DAB 서비스 대역에서 동작 가능케 한다. 3개의 공진 주파수 조정함에 있어서 상호 영향이 적기 때문에 비교적 쉽게 대역폭을 만족시킬 수 있다. 제작된 안테나는 DVB-H 서비스 대역인 $470{\sim}740\;MHz$와 DAB 서비스 대역인 $1,450{\sim}1,480\;MHz$ 대역에서 VSWR 2:1 이하의 특성을 가지며, 각각 $1.97{\sim}4.10\;dBi$와 $1.98{\sim}2.04\;dBi$의 최대 이득 특성을 갖는다.

• 한국군사과학기술학회지
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• 제22권3호
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• pp.332-340
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• 2019

Electronic warfare systems are needed to be advantageous in the modern war. Many radar threat signals with various frequency spectrums and complicated techniques exist. For detecting the threats, a receiver with wide and narrow-band digital processing is needed. To process a wide-band searching mode, a polyphase filter bank has become the architecture of choice to efficiently detect threats. A polyphase N-path filter aligns the re-sampled time series in each path, and a discrete Fourier transform aligns phase and separates the sub-channel baseband aliases. Multiple threats and CW are detected or rejected when the signals are received in different sub-channels. And also, to process a narrow-band precision mode, a direct down converter is needed to reduce aliasing by using a decimation filter. These digital logics are designed in a FPGA. This paper shows how to design and develop a wide and narrow-band digital receiver that is capable to detect the threats.

• 한국정보통신학회논문지
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• 제10권8호
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• pp.1352-1358
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• 2006

이 논문은 듀얼 반사판을 이용한 광대역 보우타이 슬롯 안테나를 제작 실험 했다. 슬롯 안테나는 넓은 도체판에 약 1/2 길이의 가늘고 긴 슬롯을 뚫게 되면 반파장 다이폴과 마찬가지로 효율이 좋고 강한 전파가 복사된다[1] 이 논문에서는 보통 사각 슬롯 보다 대역폭이 넓은 보우타이 형태의 슬롯으로 제작하였다. 먼저 단일 반사판 슬롯 안테나를 제작 실험 측정하였으며 제작된 단일 반사판 슬롯 안테나에 또 하나의 반사판을 슬롯 안테나와 반사판 사이에 삽입함으로서 대역폭을 확장하였다. 제작 실험 결과 VSWR<2.0 이하인 Low Band 대역폭은 약 $22%(793MHz\sim992MHz)$ 대역폭을 가졌으며 High Band 대역폭은 약 $61%(1626MHz\sim3064MHz)$의 대역폭을 가짐을 실험을 통해 알 수 있었다.

• 한국인터넷방송통신학회논문지
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• 제15권2호
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• pp.213-219
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• 2015

본 논문에서는 무인 항공기에 장착 가능한 초광대역 반파장 루프 안테나를 설계하였다. 설계된 안테나는 야구공 모양에 자기상보 원리(self-complementary principle)를 적용하여 광대역 특성을 얻었다. 또한 저자세로 변형하기 위해 방사체 사이에 접지면을 두어 image theory를 적용하였다. 이렇게 설계된 초광대역 반파장 루프 안테나의 크기는 $0.20{\lambda}_L{\times}0.14{\lambda}_L{\times}0.16{\lambda}_L$ (${\lambda}_L$은 최저주파수의 공기 중 한 파장)이며, -10 dB 대역폭은 50 : 1(0.3 GHz ~15 GHz) 이상으로 측정되었다. 방사패턴은 모든 주파수에서 모노폴 안테나와 유사한 패턴을 가진다. 또한 설계된 안테나를 축소된 UAV(Unmannded Aerial Vehicle)의 동체 배면에 장착하여 그 특성 확인결과 초광대역 특성을 유지하면서, 모든 주파수 대역에서 모노폴 안테나와 유사한 방사패턴을 나타내었다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.415-420
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• 2005

To construct an anechoic chamber for EMI test satisfying some international standards, it has been recognized that the absorption characteristics of the EM wave absorber must have more than 20 dB over the frequency band from 30 MHz to 18 GHz. In this paper, an EM wave absorber with super wide-band frequency characteristics was proposed and designed in order to satisfy the above requirements by using the EMCM[1]. As a result, the proposed absorber has absorption characteristics more than 20 dB over the frequency band from 30 MHz to more than 20 GHz.

• Journal of the Optical Society of Korea
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• 제11권2호
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• pp.67-70
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• 2007

A Wide Color Gamut Backlight system was studied using a three-band white Light-Emitting Diode. A three-band white light-emitting diode (LED) was fabricated using an InGaN-based blue LED chip that emits 445-nm blue peak, and a green phosphor and red phosphor that emit 535-nm green and 621-nm red peak emissions, respectively, when excited by 450-nm blue light. Using for this three-band white LED, wide color gamut backlight unit (BLU) was attained. The luminance of BLU and CIE 1931 chromaticity coordinates was $1,700Cd/m^2$ and (0.337, 0.346). Color filter matching simulations for this configuration show that the three-band white LED backlight can be enhanced by up to 16% over conventional white LED backlight color gamut.

• 천문학논총
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• 제27권4호
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• pp.147-148
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• 2012

We present a photometric catalog of infrared (IR) sources based on the North Ecliptic Pole Wide field (NEP-Wide) survey of AKARI, which covered a 5.4 $deg^2$ circular area centered on NEP. The catalog contains about 115,000 sources detected at the 9 IRC filter bands, comprehensively covering a wavelength range from 2 to $24{\mu}m$. This is a band-merged catalog including all of the photometry results from the supplementary optical data as well as the IRC bands. To validate a source at a given IRC band, we searched for counterparts in the other bands. The band-merging was done based on this cross-matching of the sources among the filter bands. The NIR sources without any counterpart in any other bands are finally excluded to avoid false objects.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.442-445
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• 2003

The use of a single UWB antenna which covers a wide range of frequencies is very desirable for future wireless communications system. In this paper, we propose a novel wide band printed elliptic monopole antenna for UWB(Ultra wide Band). Wideband planar monopole disc antenna have been recently studied. The proposed antenna can cover UWB frequencies from 3.5GHz to 12GHz. it is determined from 10dB return loss. The antenna consists of the printed elliptical monopole disc with microstrip-line feed. Elliptic disc of antenna and ground height operate important to matching. The results of measurement are almost similar to those of simulation.

• 조명전기설비학회논문지
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• 제29권8호
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• pp.98-103
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• 2015

Power plant is that very high reliability when industrial and economic impact on the overall electric power system is required, it is essential to improve the reliability, especially the fault prediction diagnosis. Since an accident caused by the partial discharge in the power plant is above state has a faster response characteristic than the other indications in the case of any, the partial discharge generated in the power plant immediately detect the deterioration of insulation due to the accident of the power plant and the non-drawn It should prevent or reduce. Partial Discharge Measuring Systems for UHV SF6 Gas Insulated Switchgear and power transformer on site installed has some probability of abnormal recognition in case of non-flexible deal with on site noise. Many methode to eliminate these kinds of noises, UHF Detection System is chosen as purchase description in Korea, but this system having a bandwidth between 500MHz 1.5GHz wide band. Initial install periods(about 20 years ago), this band had no strong signal source, but in these days this wide band have strong signals, such as LTE. So, module described in this paper is designed as simultaneously use with wide and narrow band for solve this noise problem, and introduce this system.