• 전기전자학회논문지
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• 제3권2호
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• pp.168-177
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• 1999

이 논문은 디지털 영상에 대한 에지를 보존하는 새로운 영상 보간 방법을 제안한다. 일반적인 보간 기법은 선형 연산자를 이용한 저역필터를 사용함으로써 원 영상의 고조파 성분에 대한 정보를 손실하는바 high contrast 에지 부분에서 희뿌옇게 되는 현상과 톱니현상이 일어나 영상 선명도가 떨어지는 경향이 있었다. 본 논문에서는 이러한 단점을 개선한 새로운 보간 기법을 제시한다. 본 논문에서 제시한 보간 알고리즘은 퍼지 연산자를 이용하여 입력 영상 데이터의 성질에 따라 고주파 성분과 저주파 성분을 달리 조절함으로써 원래 영상에 가까운 해상도를 얻을 수 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.418-421
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• 2003

In this thesis, a new channel estimation technique is proposed for orthogonal frequency division multiplexing (OFDM) over time varying channels. The channel estimation algorithm exploits the fact that the estimated channel impulse response (CIR) by using pilot signal is the average value of the CIR variation within an OFDM symbol period. With this fact, the CIR variation is simply estimated through lowpass interpolation of the CIRs of the adjacent OFDM symbols. For signal detection, a time domain equalizer is used in this thesis. Simulation results show that the proposed system improves the bit error rate (BER) over time varying channels.

• Tribology and Lubricants
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• 제17권1호
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• pp.33-39
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• 2001

A method of calculating wear volume is developed using the signal processing technique. The lowpass filter with Fourier transform and the “windowing” are implemented in the method. User-defining feature is also included in determining the cutoff frequency of the low-pass filter and the baseline for the volume integration. Commercial software, MatLab, is used for the programming. Since the method uses the original wear data without simplifying the wear shape, it can give a further accurate result than the previously utilized methods, which often adopted the simplification. It becomes further powerful if the contacting body has a general shape rather than that gives well-formed surface traction (e.g., the Hertzian). The validation of applying the average surface roughness, Ra, to the “windowing” and the baseline for volume integration is discussed.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.343-346
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• 2003

A new structure to design low pass filters (LPFs) is presented rho proposed structure has the etched shape of Quad-Spiral DGS(Defected Ground Structure) on microstrip transmission lines. By extracting the equivalent circuit elements of unit Quad-Spiral DGS, LPFs are designed easily. The equivalent circuit of Quad-Spiral DGS consists of a step impedance resonator and lumped elements. The proposed LPF provided steep rejection characteristics with 5-poles. Experimental results show excellent agreements with circuit simulation results in wide band and the validity of our circuit modeling for LPF design. The result shows another possibility of Quad Spiral DGS for microwave devices.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.265-268
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• 2003

In this paper, we introduce the SIR typed bandpass filters in CPW structures for shifting spurious harmonic frequency into higher frequency band. And we proposed the effective feed structures for suppressing spurious frequency in the SIR typed CPW bandpass filters. The designed folded feed structures have lowpass filtering characteristic. They are very effective feed types in the CPW bandpass filters for suppressing harmonics. The measured results of the CPW bandpass filter with folded feed line shows that it has suppressed and wide out-of-band up to 5.8fo.

• 전기학회논문지
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• 제56권2호
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• pp.424-427
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• 2007

A fully differential transconductor using the series composite transistor is proposed. Simulation results show that THD is less than 1.2% for the differential input signal of up to $1.5V_{p-p}$ when the input signal frequency is 10MHz. i he proposed transconductor is used to design a third-order elliptic Gm-C lowpass filter with 138kHz cutoff frequency for ADSL Tx filter. The design procedure is based on signal flow graph(SFG) of a doubly-terminated LC ladder filter by means of fully differential transconductors and capacitors. The filter is fabricated and measured with a $0.35{\mu}m$ CMOS process.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1927-1928
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• 2008

가변 이득 및 차단주파수 특성을 가지는 5차 CMOS Gm-C 필터를 설계하였다. 설계된 필터는 CMOS 차동 트랜스컨덕터들로 구성하였으며 트랜스컨덕터들은 각각 전압 조정에 의하여 트랜스컨덕턴스 값이 변환되도록 설계하였다. 가변 차단주파수 특성은 외부잡음으로 발생할 수 있는 필터 차단주파수의 변형을 보상할 수 있고 한 개의 필터로써 다중대역 수신 단에 적용할 수 있도록 하고자 하였다. HSPICE 시뮬레이션 결과, 1.5MHz$\sim$3.5MHz의 차단주파수의 조정이 가능하였고 이득은 -2.8dB$\sim$2.6dB으로의 조정이 가능하였다.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.202-204
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• 2006

A new method is presented to design RF filters without the Similarity Transform of their coupling coefficient matrix as circuit parameters which is very tedious due to pivoting and deciding rotation angles needed during the iterations. The transfer function of a filter is directly used for the design and its desired form is derived by the optimized rational-function fitting technique. A 3rd order Coaxial Lowpass filter and an 8th order dual-mode elliptic integral function response filter are taken as an example to validate the proposed method.

• The Journal of the Acoustical Society of Korea
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• 제18권1E호
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• pp.13-19
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• 1999

This paper introduces an adaptive wavelet transform based on the lifting scheme, which is applied to signal denoising. The wavelet representation using orthogonal wavelet bases has received widespread attention. Recently the lifting scheme has been developed for the construction of biorthogonal wavelets in the spatial domain. Wavelet transforms are performed through three stages: the first stage or Lazy wavelet splits the data into two subsets, even and odd, the second stage calculates the wavelet coefficients (highpass) as the failure to interpolate or predict the odd set using the even, and the third stage updates the even set using neighboring odd points (wavelet coefficients) to compute the scaling function coefficients (lowpass). In this paper, we adaptively find some of the prediction coefficients for better representation of signals and this customizes wavelet transforms to provide an efficient framework for denoising. Special care has been given to the boundaries, where we design a set of different prediction coefficients to reduce the prediction error.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권10호
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• pp.598-605
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• 2003

In this paper, we propose the method that separates PPG signal and motion artifact signal from two input signals using new independent component analysis algorithm in time domain. In order to eliminate the large level artifact efficiently, block interleaving. lowpass time filtering and innovation processing technique were applied in ICA preprocessing, and FastICA algorithm were applicable. Experiments are made with the numerical simulation and the real PPG signal including four kinds of motion artifact pattern. Our results show that ICA can effectively detect, separate and remove motion artifact in input signals. Then from the separated signals we restore the original PPG signal and propose a new method which computes SpO$_2$ using ICA mixing matrix.