• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12A
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• pp.1346-1353
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• 2007

In this paper, the methods are presented for the calculation of general coupling coefficient matrixes used in the band pass filter design. They are calculated from transmission coefficient($S_{21}$) and reflection coefficient($S_{11}$) with desired characteristics derived from the poles of filter function and return loss(RL). The calculated matrixes from this method are transformed to the folded canonical filter structure using similarity transformation which lends us the practical filter design. Based on the resulting matrix, the folded canonical filter has been designed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.5
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• pp.112-118
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• 2002

The adaptive m filters is more effective than m filters when acoustic feedback exists, in which cause an order of a FIR filter must be very large if some of poles of the ideal control filter are near the unit circle. But the IIR filters may have stability problems especially when the adaptive algorithm is not converged. In this paper, a stabilizing procedure for adaptive IIR filters is proposed. In the beginning of the ANC system, it improve a stability by pulling the poles of the IIR filter to the center of the unit circle, and it returns the poles to their original positions after the filter converge. Computer simulations and experiments are performed to show the effectiveness of proposed schemes.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.107-110
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• 2000

전력선 통신을 이용한 조광제어 시스템은 전자식 안정기의 주파수 변조 방식을 잉요하여 실시하였다 전력선 통신제어 사용된 data 변조 방식은 FSK 방식을 이용하였으며 안정기의 스위칭 동작에 의해 발생하는 EMI는 140kHz 대역의 노이즈를 발생시키므로 본논문에서는 2단 필터를 사용하여 해당 대역의 EMI 60dB 감쇄시켰다.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.71-76
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• 2001

An electret filter is composed of permanently charged electet fibers and is widely used in applications requiring high collection efficiency and low-pressure drop. In this work, the collection efficiency of the filter media used in manufacturing cabin air filters was investigated by using poly-disperse particles when submicron particles are loaded. Long-term experiments were conducted by applying different charging states, which are spray electrification and charge equilibrium by bipolar ionization. In order to investigate on the effect of particle loading in filter media, NaCl particles were generated from 0.1% and 1% solutions by an atomizer. In NaCl 0.1%, the collection efficiency of electret filter decreased and then did not change in equilibrium state. In the case of relative larger particles of NaCl 1%, collection efficiency for the equilibrium charged particles increases due to the particle loading on the filter fibers. Particles charged by spray electrification are small in collection efficiency after equilibrium state and increase of filter media's pressure drop was very low in comparison of the equilibrium charged particles.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.2
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• pp.83-91
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• 2012

An RF energy detector for spectrum sensing in TV white space transceiver is presented. It is based on an RF active filtering technique that comprises a low-noise amplifier with a frequency-translation high-pass filtering feedfoward loop, which attenuates the unwanted sideband energy and only passes the wanted band energy. Unlike the conventional architecture, a new architecture that can attenuate both sidebands at the same time is proposed. A simplified system modeling method is presented to assess the non-ideality effects on the RF energy detector performances. System behavioral simulations demonstrate that the proposed architecture can be instrumental for realizaing a RF energy detector circuit in CMOS.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.1623-1626
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• 2005

초음파 영상 기법은 장기, 연조직, 혈류를 검사하는데 쓰이는 영상 진단법이다. 초음파 장비를 통해 얻어진 초음파 볼륨 데이터는 장비 특성상 많은 잡음(speckle noise)을 포함하기 때문에, 깨끗한 영상을 얻기 위해서는 잡음 필터링(noise filtering)이 필요하다. 그런데, 볼륨 데이터 모든 영역에 대해 잡음 필터링을 적용할 경우 전처리 시간이 길어져 실시간으로 초음파 볼륨 데이터를 렌더링하기 어렵다. 본 논문에서는 실시간으로 입력되는 초음파 볼륨 데이터를 가시화 하기위하여 전처리 시간 없이 잡음을 제거하는 방법을 제안한다. 전처리 시간에 전체 볼륨 데이터에 대해 잡음 필터링을 적용하지 않고, 영상을 생성하는 동안 참조되는 복셀(voxel)에 대해서만 잡음 필터를 적용하여 얻은 값을 사용한다. 이때 필터링에 소요되는 시간을 최소화하기 위해 가장 단순한 평균화 필터를 사용한다. 그리고 복셀에 적용되는 3차원 필터를 3단계의 1차원 필터 연산 단계로 분할 한 후, 각 단계별 연산을 거친 복셀들에 대해서는 다시 연산을 하지 않도록 하여 중복을 피한다. 이를 통해 전처리 시간 없이 기존 방법과 동일한 화질을 유지하는 최종 영상을 만들어 낸다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.7
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• pp.922-934
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• 1993

In this paper, statistical properties of the spatiotemporal center weighted median(CWM) filter for image sequences are investigated. It is statistically shown that the CWM filter preserves image structures under motion at the expense of noise suppression. To improve the CWM filter, a filter which can be effectively used in image sequence processing, the adaptive directional center weighted median filter (ADCWM), is proposed. This filter utilizes a multistage filtering structure based on adaptive symmetric order statistic(ASOS) operators which produce a pall of order statistics symmetric about the median. The ASOS's are selected by using adaptive parameters adjusted by local image statistics. It is shown experimentally that the proposed filter can preserve image structures while attenuating noise without the use of motion estimation.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.85-90
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• 2001

This work presents experimental results of filter media test by using particles from $0.02\;to\;0.6{\mu}m$ in diameter and by applying different charging states. In order to investigate the electret filter performance, the collection efficiency and the pressure drop of filter were measured. The face velocities of test filters varied from 2.4 to 20.4 cm/s. Another experiment setup for the cartridge cabin air filter was used to get an collection efficiency in submicron region. After charging level of electret filter severely decreased, the change of collection efficiency was verified. Experimental results show that the reliability of electret filters can be poor in some conditions.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.15-18
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• 2000

회전기에서 발생하는 소음성 잡음의 경우 능동잡음 제어를 이용 진폭이 상대적으로 큰 주기성 저주파 잡음 제어로 상당한 감쇄효과를 얻을 수 있다. 본 논문에서는 주기적 저주파 잡음을 효과적으로 제거하는 부밴드 능동잡음제어 구조를 제안하였다 이 구조에서는 QMF를 이용, 진폭이 큰 주기적 저주파신호를 분리하여 적응측엽제거 원리를 적용하여 저주파 신호를 제거한다. QMF에서 발생하는 지연은 각 필터를 통과한 신호경로에 적응필터를 사용하여 보상하였다. 그리고 적응필터 성능향상을 위해 최적 적응이득을 해석적으로 구하여 사용하였다.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.884-886
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• 2005

본 논문에서는 확장 칼만 필터를 이용하여 직류 모터의 동특성을 실용적으로 모델링하는 방법을 제안한다. 먼저 시험을 통해 모터의 주파수 별 응답 특성을 추출하고 이로부터 확장 칼만 필터를 이용하여 출력 전압의 이득 감쇄와 위상 지연을 추정한다. 추정된 값을 이용하여 모터의 선형 동특성을 모델링하고, 각각의 비선형 요소를 추가시키면서 모델 출력과 실제 시험을 통해 획득한 각속도 출력의 RMSE (Root Mean Square Error)를 최소화시키는 비선형 계수 값을 산출하여 최종적인 직류 모터의 모델을 완성한다.