• 한국콘텐츠학회논문지
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• 제9권11호
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• pp.37-45
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• 2009

인터넷 서비스가 주 정보원으로 작용하는 정보화 시대에 인터넷 망이 닿지 않는 지역에 인터넷 서비스를 제공하기 위해 전력선 통산이 이루어지고 있다. 하지만, 전력선은 통신 선로가 아니므로 통신 신호의 흐름에 따라 방사되는 전파가 발생하고, 그 전파는 기존에 그 대역을 사용하는 무선 통신 서비스와 간섭이 발생하게 된다. 본 논문에서는 전력선 통신과 무선 통신 서비스의 상호 간섭을 줄이기 위해 스펙트럼 센싱 기술과 Notch Filter 적용 방안을 제안하였다. 스펙트럼 센싱은 주변의 허가된 무선국을 보호하기 위해 주변 무선 환경을 탐색하여 빈 주파수 대역을 찾아 임시적으로 주파수 대역을 사용할 수 있도록 하는 Cognitive Radio(CR)기술의 핵심 기술이다. 또한, 각각의 스펙트럼 센싱 모듈과 Notch Filter의 기능들을 임베디드 보드를 통하여 구현하였다.

• 대한전자공학회논문지
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• 제22권6호
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• pp.63-70
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• 1985

Unilateral Fin-Line 구조와 I-평면 구조를 Rayleigh-Ritt의 변분법으로 해석하는 방법을 제시하고, Cohn의 여파기 설계 이론에 의해 대역통과 멸파기를 설계하는 CAD프로그램을 개각했다. 관내 재역폭이 5%∼24.6%인 Unilateral Fin-Line 여파기를 제작하여 수험과 이론이 일치함을보였다. 시험 결과, 삽입손실이 0.17∼0.2545의 저손실 여파특성을 얻었으며 중심주파교에 대한 오차는 0.2%이 내였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.19-22
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• 2002

In this paper, we aims to develop a microcontroll er-based ECG monitoring system and portable pulse oximeter using Compact Flash Interface. First, portable pulse oximeter system is designed to record 2 channel of biosignals simultaneously, including 1 channel of $SpO_2$ and 1 channel of pulse rate. It is very small and portable. Besides, the system makes it possible to measure a patient's condition without an additional medical equipment. We tried to solve the problems generated by a patient's motion. That is, we added an analog circuit to a traditional pulse oximeter in order to eliminate the change of the base line. And we used 2D sector algorithm. As present, SpO2 modules are completed. But there are still many further development needed in order to enhance the function. Especially, compact falsh interface remains the most to complete. Second, ECG monitoring system uses almost same as present 3-lead ECG system. But we focus on the analog part, especially in filter. The proposed filter is composed of two parts. One is a filter to remove the power-line interface. The other is a filter to remove the baseline drift. A filter to remove the power-line and the baseline drift is necessarily used in the ECG system. The implemented filter have three features; minimizing the distortion in DC component, removing the harmonic component of power-line frequency. Using compact flash interface, we can easily transfer a patient's personal information and the measured signal data to a network based server environment. That means, it is possible to implement a patient's monitoring system with low cost.

• 한국통신학회논문지
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• 제28권10A호
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• pp.847-852
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• 2003

본 논문에서는 접지면에 PBG 및 Aperture의 기능을 하는 셀을 에칭함으로써 PBG에의한 광대역 저지대역 여파기특성을 이용하여 본래 스트립라인이 가지고 있는 하모닉 성분(Second, Third Harmonic and etc)을 억제하였으며, Aperture 특성에 의하여 밴드폭이 넓어지는 2가지 효과를 동시에 볼 수 있는 셀을 제안하였다. 대역통과 여파기는 결합 스트립 여파기를 사용하였다[l]. 대역통과여파기의 대역폭은 신뢰할 수 있는 길이인 0.2mm를 구현할 수 있도록 맞추어 설계하여 대역폭을 가능한 넓게 만들었고 기판은 유전율이 3.2인 기판을 사용하였다. 필터의 중심주파수는 2.14GHz, 대역폭은 230MHz를 얻었다. 이를 Aperture를 통해 310MHz까지 80MHz 즉, 34.7%까지 증가시켰으며 PBG를 통하여 하모닉성분(2nd, 3rd, 4th, 5th)을 20-30dB까지 억제하였다.

• Journal of electromagnetic engineering and science
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• 제5권2호
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• pp.80-86
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• 2005

In this paper, a novel varactor-tuned combline bandpass filter is presented. The coupling varactor diode between line elements is introduced to control the passband bandwidth so that the passband bandwidth can be maintained almost constant within the tuning range. The equivalent circuit and design equations are derived, and the optimum design is discussed. A 1.7 GHz, two-pole bandpass filter with a bandwidth of $4.5\%$ was constructed. The absolute passband bandwidth was maintained almost constant within more than 0.4 octave tuning range.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
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• pp.764-768
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• 2004

This paper proposed Hybrid Filter for harmonics elimilation on the power line. It's control method is very simple, but its performance is better than the results by passive filter. For the harmonics elimination, we improved the performance of the BPF(Band-pass Filter) with the GIC(Generalize Impedance Converter), and the new hysterisys controller.

• Journal of Electrical Engineering and Technology
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• 제8권2호
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• pp.371-375
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• 2013

The design of a new compact UWB bandpass filter is proposed, which has cascaded center-tapped microstrip composite right/left-handed transmission-line zeroth-order resonators (CRLH-TL ZORs). In an attempt to reduce the size, instead of the conventional half-wavelength resonators or periodic and multiple CRLH-TL cells, only one cell ZOR geometry is adopted as each resonator in the filter. Additionally, two center-tapped ZORs are coupled to increase the slope of the skirt. Besides, stepped impedance matching parts are placed in the paths to the input and output ports to enhance passband and stopband performances. The proposed filter is shown to have the overall size of $0.69{\lambda}_g{\times}0.70{\lambda}_g$, the insertion loss much less than 1 dB, and an acceptable return loss performance in the predicted and measured results.

• Current Optics and Photonics
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• 제2권6호
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• pp.563-567
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• 2018

We propose and experimentally demonstrate a simple tunable photonic microwave band-pass filter with high resolution using a reflective semiconductor optical amplifier (RSOA) and an optical time-delay line. The RSOA is used as a gain medium for generating cross-gain modulation (XGM) effect as well as an optical source. The optical source provides narrow spectral width by self-injection locking the RSOA in conjunction with a partial reflection filter with specific center wavelength. Then, when the RSOA is operated in the saturation region and the modulated recursive signal is injected into the RSOA, the recursive signal is inversely copied to the injection locked optical source due to the XGM effect. Also, the tunability of the passband of the proposed microwave filter is shown by controlling an optical time-delay line in a recursive loop.

• 한국항해학회지
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• 제22권4호
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• pp.59-67
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• 1998

A quick and automatic detection with no harm to the goods is very important task for improving quality control, process control and labour reduction. In real fields of industry, defect detection is mostly accomplished by skillful workers. A narrow band eliminating spatial filter having characteristics of removing the specified spatial frequency is developed by the author, and it is proved that the filter has an excellent ability for on-line and real time detection of surface defect. By the way,. this spatial filter shows a ripple phenominum in filtering characteristics. So, it is necessary to remove the ripple component for the improvement of filter gain, moreover efficiency of defect detection. The spatial filtering method has a remarkable feature which means that it is able to set up weighting function for its own sake, and which can to obtain the best signal relating to the purpose of the measurement. Hence, having an eye on such feature, theoretical analysis is carried out at first for optimal design of narrow band eliminating spatial filter, and secondly, on the basis of above results spatial filter is manufactured, and finally advanced effectiveness of spatial filter is evaluated experimentally.

• 한국전자파학회논문지
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• 제19권2호
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• pp.114-120
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• 2008

본 논문에서는 일반적인 반 파장 평행 결합 선로 대역 통과 필터의 입 출력 결합 선로를 K-인버터로 변환하고, K-인버터를 $\pi$-형 전송선 등가로 대체함으로써 $\pi$-형 전송선 급전 구조를 갖는 구조의 대역 통과 필터를 제안하였다. 이 방법은 반 파장 결합 선로 대역 통과 필터의 입 출력 결합 선로 구현 문제에 대한 해결 방안을 제시한다. 또한, 기존의 탭 선로(tapped line) 구조의 설계 방법에 비해 설계 식이 매우 간단하고 정확하여, 특성의 적정화를 위한 노력과 시간을 상당히 줄일 수 있다. 제안된 이론을 바탕으로 $\pi$-형 전송선 급전 구조를 갖는 구조의 대역 통과 필터를 설계 및 제작하였고, 그 결과로부터 제안 방법의 타당성을 입증하였다.