• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1946-1949
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• 2002

본 논문에서는 밀리미터파 대역에서 저손실 특성이 우수한 전송선로인 non-radiative dielectric (NRD) guide와 microstrip의 transition에 관해 연구하였다. 본 연구에서 이용된 transition은 aperture coupling을 이용한 것으로 NRD와 microstrip 사이의 aperture를 통하여 magnetic field가 coupling되는 원리이다. Aperture의 구조를 각각 rectangular와 ridge 형태로 설계하였다. 비교를 위해서 설계된 microstrip to microstrip transition의 경우 aperture의 구조를 ridge 형태로 했을 때 rectangular 일 때 보다 삽입손실 특성이 개선되었고 더 넓은 bandwidth를 가지는 것을 알 수 있었다 NRD to microstrip transition의 경우는 bandwidth 면에서 ridge 구조와 rectangular 구조 모두 비슷한 특성을 보였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.1075-1078
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• 2000

본 논문에서는 무선선로상의 제약과 무선 단말기의 제한된 자원을 이용하여 무선 인터넷 서비스를 좀 더 효율적으로 제공하기 위한 WBMP(Wireless BitMaP) 변환기와 해석기의 설계 및 구현에 대하여 기술한다. WBMP 변환기는 기존의 이미지를 단색의 압축되지 않은 형태인 WBMP 이미지로 변환하고, 단말기 내의 WBMP 해석기는 WBMP 이미지를 해석하여 브라우저를 통해 나타낸다. WBMP 이미지는 헤더의 구조가 간단하고, 이미지 표현에 사용되는 데이터의 양이 적으므로 무선 환경에 적합한 형태이다. 그러나 컬러 이미지를 변환하면 이미지 정보가 손실되거나 왜곡될 수 있고, 표현된 컬러의 수가 많을수록 손실률은 높아진다. 따라서 향후 그레이-레벨 이미지 또는 컬러 이미지로의 변환 및 해석 기능을 확대 적용할 필요가 있다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.6
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• pp.38-47
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• 2008

In this paper, the narrow band-pass filter with compact-size using the ${\lambda}g/2$ open stubs is proposed. The filter size is reduced by realization of transmission line at second harmonics and at the same time the power can be transferred to the output by using the fundamental wave generated in the resonator and the transmission line in which the impedance mismatch technique is adopted. Thus, the proposed filter can be reduced to half-length of horizontal transmission line than the conventional one. The experimental results show that insertion loss is 1.58 dB and return loss is 9.86 dB, and the fractional bandwidth is 10 % at the center frequency of 5.8 GHz. The filter size is $10.34{\times}18.56\;mm2$.

• Journal of IKEEE
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• v.3 no.1 s.4
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• pp.79-85
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• 1999

In this paper, the resistive mixer for 5.86Hz wireless LAN, main part receiving system, was designed and implemented. The noise characteristics and the linearity in the base band was superior. For the use of local oscillator of mixer, dielectric resonator of stable output and temperature characteristics was designed. For the electrical tuning by the capacitance variation of varactor diode, the microstrip line and magnetic coupling characteristics of the dielectric resonance was used. It was obtained that gain of the proposed resistive mixer containing the RF cable loss, is -13.8dB, the conversion loss of frequency converter is -12 dB, and the output power of local oscillator is 1.67 dBm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.5 s.96
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• pp.472-481
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• 2005

This paper reports the design of RFID reader antennas working in UHF band. The reader antennas were designed using a Pareto Genetic Algorithm(Pareto GA). Antennas were optimized to have circular polarization(CP) with less than 3 dB axial ratio, impedance matching with less than VSWR=2 within the frequency range of UHF, an adequate readable range, a restricted size(kr<2.22) considering the practical condition. After Pareto GA optimization, we selected and built the most suitable antenna design and compared the measured results to the simulations. Operating principle of the antenna was explained by investigating the amplitude and the phase of the induced current on the antenna body. We also researched the stability of the antenna with respect to the manufacturing error and studied the critical design parameters by applying the random error method on the antenna bent points.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.105
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• pp.101-109
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• 2006

A broadband, DC to 40 GHz 5-bit MMIC digital attenuator has been developed. The ultra broadband attenuator has been achieved by adding transmission lines in the conventional Switched-T attenuator and optimizing the transmission line parameters. Momentum simulation was performed in design for accurate performance prediction at high frequencies and Monte Carlo analysis was applied to verify the performance stability against the MMIC process variation. The attenuator has been fabricated with $0.15\;{\mu}m$ GaAs pHEMT process. This attenuator has 1 dB resolution and 23 dB dynamic ranges. High attenuation accuracy has been achieved over all attenuation ranges and 40 GHz bandwidth with the reference state insertion loss of less than 6 dB at 20 GHz. The input and output return losses of the attenuator are better than 14 dB over all attenuation states and frequencies. The measured IIP3 of the attenuator is 33 dBm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.11
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• pp.84-90
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• 2010

In this paper, the reduced size of broad bandpass filter with parallel coupled line structure is presented. This proposed filter can control bandwidth of narrow to broadband by adjusting the coupling coefficient. The conventional filter is operated with a narrow band. If a higher bandwidth is desired than the conventional narrow bandwidth, it is hard to realize due to the coupling coefficient between feeding line and resonator. In this paper, to overcome this limitation, a proposed bandpass filter is designed with reduced size due to SIR(Stepped Impedance Resonator) and multi-grade type structures than conventional one, and it has characteristics of adjusting bandwidth freely as per quantity of coupling coefficient. The proposed bandpass filter that, experimental results of insertion and return losses are 0.42 dB and 20.9 dB with bandwidth of 60 % at the center frequency of 5.8 GHz, respectively.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.10
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• pp.929-934
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• 2016

In this paper, we studied the design and fabrication of array antenna at around 1.8 GHz band. To improve of frequency properties of antenna, single feed microstrip patch antenna was simulated by HFSS(High Frequency Structure Simulator). A $1{\times}2$ array antenna of 1.8 GHz for LTE band was designed and fabricated by photolithography on an FR4 substrate (dielectric constant of 4.4 and thickness of 0.8 mm). The fabricated antenna was analyzed by network analyzer. The measured results agree well with the simulations, which confirmed the validity of this study. The fabricated $1{\times}2$ array antenna showed a center frequency, the minimum return loss and impedance were 1.82GHz, -30.5dB, and $49.6{\Omega}$ respectively.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.223-224
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• 2015

배전 계통 산업 현장에서는 스위칭 소자 및 제어장치, 전 자기기들이 한 대 맞물려 증가하고 있다. 또한, 스마트 그리드(Smart Grid) 및 마이크로 그리드(Micro Grid)의 개념이 도입되면서 분산 전원 이 널리 보급되고 있다. 이로 인해 현장에서는 많은 전기전자기기들이 설치되어 운영 중에 있고, 이것은 noise 및 고조파와 같은 왜란이 발생 되는 원인을 초래하고 있다. 왜란은 여러 전기 전자 장비들의 데이터 취득 왜곡 현상을 발생시키고, 이러한 데이터 손실로 인해 기기들의 오동작 및 사고를 발생시킨다. 대표적인 왜란으로는 common mode noise 같은 대지(大地) 등의 기준점과 각 신호선 사이에 나타나는 노이즈가 있으며, 선로 및 장비 특성에 따라 기수 및 우수 고조파가 있다. 이러한 왜란들은 전자기기들의 오동작 및 신호의 부 정확성으로 제품 신뢰성에 문제를 초래한다. 특히 데이터 계측 실패 및 Serial 통신을 함에 있어서 신호 손실을 발생시켜 데이터 변형을 초래한다. 이로 인해 배전선로에 위치한 전자기기들이 왜곡된 데이터로 동작을 하게 되고 이는 곧 선로의 사고를 발생시키게 된다. 따라서 왜란들을 사전에 방지하여 기기 오동작 및 부동작을 예방하기 위해서 산업계에서는 왜란에 대한 인식을 지속적으로 증가시키고 있다. 실제 현장에서도 이와 같은 왜란으로 인해 기기 오동작을 하는 경우가 많으며 이를 해결하기 위한 여러 신호처리 기법을 적용하고 있다. 이에 본 논문에서는 여러 종류의 샘플링 데이터 량을 생성할 수 있도록 샘플링 속도를 다변환(Multi-interchange)하고 각 샘플링 속도에 맞게 계측된 샘플링 데이터를 DFT 신호 처리하여 왜란으로부터 강건한 계통 주파수를 계측한다. 또한, 주파수 별 DFT 값을 Table화 하여 계통 주파수를 찾아낸다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4A
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• pp.407-413
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• 2011

In this paper, the reduced size of broad bandpass filter with parallel coupled line structure is presented. This proposed filter can control bandwidth of narrow to broadband by adjusting the coupling coefficient. The conventional filter is operated with a narrow band. If a higher bandwidth is desired than the conventional narrow bandwidth, it is hard to realize due to the coupling coefficient between feeding line and resonator. In this paper, to overcome this limitation, a proposed bandpass filter is designed with reduced size due to SIR (Stepped Impedance Resonator), U-shaped open stub with hair-pin and vertical-type structure than conventional one, and it has characteristics of adjusting bandwidth freely as per quantity of coupling coefficient. The proposed bandpass filter that, experimental results of insertion and return losses are 0.42 dB and 24.5 dB with bandwidth of 60 % at the center frequency of 5.8 GHz, respectively.