• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.274-277
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• 1999

자동차 오디오는 차량의 상품성에 큰 영향을 미치고 있다. 고급 차량일수륵 또한 젊은 층일수록 차량 구매시 선택의 기준이 되기도 한다 그러나 자동차 오디오는 크게 두가지 면에서 가정용 오디오와 차이가 있다. 첫번째는 청취공간이 매우 헙소하다는 것이고 둘째로는 주행시 차량소음이 차 실내로 유입되어 오디오 음질에 영향을 미친다. 차 실내는 즘은 공간 음향폭성으로 인한 음향 dip 현상이 발생하며 이는 오디오 음질의 왜곡을 가져오므로 이를 개선하기 위해서는 라우드스피커 최적배치 뿐 아니라 주행소음에 대한 시험 및 분석을 하여 오디오 음질에 영향을 주는 주파수 밴드를 파악하여야 한다 본 논문에서는 오디오 음에 차량소음이 섞인 경우에 대하여 차량의 라우드스피커 위치는 변경하지 않고 라우드스피커의 주파수 밴드별 출력을 디지털필터를 이용하여 수정하는 방법으로 음질 개선을 제안하였다. 디지털 필터의 보정치는 차량 주행소음 특성과 차 실내 음향특성을 고려하였다. 차량소음을 섞은 주파수 옥타브 밴드 분석법을 이용한 객관적인 분석과 감성적 분석법인 NCB곡선으로 차량소음을 분식하여 디지털 필터 보정치를 구하는데 사용하였다. 제안한 9가지 디지털 필터를 이용하여 차량소음과 음악을 합성하였고 이중에서 좋은 음질에 대한 판정을 하기 위해 Scheffe가 제안한 7점 주관 평가법을 사용하여 64명이 내린 주관평가를 수행하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.12B
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• pp.2052-2059
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• 2000

Digital IF(Intermediate Frequency) 처리단과 같은 고속과 저전력을 요구하는 필터에서 덧셈기만을 사용하여 CSD(Canonical Signed Digit)형의 필터계수들을 구현하는 구조가 널리 연구되고 있다. 본 논문에서는 선형위상 FIR(Finite Impulse Response) 필터의 CSD형 필터계수들을 최소의 덧셈으로 구현할 수 있는 아키텍처를 제안한다. 1과 -1로 이루어진 필터계수 표에서 공통패턴을 공유함으로서 덧셈의 수를 줄이는 방법이 이미 연구되었다. 본 논문은 비트 shift, 비트 add, 비트 반전을 통하여 인공의 공통패턴을 만들어서 이미 존재하는 공통패턴에 합류시킴으로서 덧셈의 수를 더욱 줄일 수 있는 방법을 제안한다. CDMA 이동통신 단말기의 IF단에 사용되는 사양의 디지털 필터를 73탭의 CSD형 계수로 구현하여 9.2%의 덧셈 감소의 효과가 있음을 보였다.

• Journal of Digital Convergence
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• v.12 no.8
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• pp.329-335
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• 2014

Collaborative filtering has been popular in commercial recommender systems, as it successfully implements social behavior of customers by suggesting items that might fit to the interests of a user. So far, most common method to find proper items for recommendation is by searching for similar users and consulting their ratings. This paper suggests a new similarity measure for movie recommendation that is based on genre interest, instead of differences between ratings made by two users as in previous similarity measures. From extensive experiments, the proposed measure is proved to perform significantly better than classic similarity measures in terms of both prediction and recommendation qualities.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.2
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• pp.461-466
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• 2013

As the technology of the digital information age has developed rapidly, lots of research has been done on the digital image processing techniques, such as the image restoration. However, the SM(Standard Median) filter is a typical method of recovering the image which are corrupted by the impulse noise, this method will also reduce the quality of image by generating an error in the edge region. In this paper, in order to restore the corrupted images in the impulse noise environment, a modified median filter algorithm is proposed, which uses the pixels as the center and takes double mask. By using the double mask, we are succeeded in acquiring the excellent performance on noise-canceling, edge preservation, and also in improving the quality of image.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.758-761
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• 2007

Digital signal processing technique is applied in wide fields such as speech processing, image processing and spectrum analysis. Therefore, in order to do frequency selective operation digital filter is used in stead of analog filter and sharp filter characteristics can be implemented. Since finite impulse response (FIR) digital filter as nonrecursive type represents linear phase response characteristics and is always stable and is used in fields regarding wave information importantly such as data transmission. And due to frequency characteristics, in order to remove the Gibbs phenomenon generating around a discontinuous point, filter is designed through window function method. Therefore, in this paper to improve performance of FIR digital filter, a modified window function was applied. And the proposed method was compared with conventional methods using peak side-lobe and transition properties in simulations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.12
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• pp.2701-2706
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• 2009

There are Impulse noise and AWGN in a general image processing. Various methods have been proposed to remove these noises. Well-known filters are Mean, Min-max and Median filter and these show different characteristics depending on the noises. When Impulse noise and AWGN are in superposition environment, single filter doesn't remove noises well. Therefore in this paper, we suggested a switching filter using a probability of noise to restore images in this environment. And we compared a filter with conventional method through simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.3
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• pp.189-199
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• 1987

This paper describes a method to perform the conversion between two widely used multiplexing techniques in telephony. TDM and FDM. This method is based on the digitized Weaver modulator for single side-band modulation, and makes use of a PV digital filter which has commutativity with sinusoidal modulators and periodicity of coefficients. Thus we greatly reduce the complexity and multiplication rate of the system.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2002.11a
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• pp.179-182
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• 2002

본 논문에서는 디지털 이퀄라이저에 대하여 검토하고, 대역 및 이득에 따라 Q-factor를 가변시키는 디지털 이퀄라이저 필터를 제안한다. 제안한 기법은 고정된 Q-factor를 사용하거나, 대역에 따라 Q-factor를 결정하는 기존의 방법들에 비해 가청 주파수 영역에서의 대칭성과 이득 리플 등의 측면에서 우수하고, 기존의 방법과 동일한 수준의 하드웨어 복잡도를 보인다. 또한, 중심 주파수 선정에 따른 성능 변화에 대해서도 고찰한다.

• Journal of radiological science and technology
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• v.38 no.4
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• pp.347-353
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• 2015

The purpose of this study is to suggest proper additional filtration by comparisons patient dose and image quality among additional filters in digital chest tomosynthesis (DTS). We measured the effective dose, dose area product (DAP) by changing thickness of Cu, Al and Ni filter to compare image quality by CD curve and SNR, CNR. Cu, Al and Ni exposure dose were similar thickness 0.3 mm, 3 mm and 0.3 mm respectively. The exposure dose using filter was decreased average about 33.1% than non filter. The DAP value of 0.3 mm Ni were decreased 72.9% compared to non filter and the lowest dose among 3 filter. The effective dose of 0.3 mm Ni were decreased 48% compared to 0.102 mSv effective dose of non filter. At the result of comparison of image quality through CD curve there were similar aspect graph among Cu, Al and Ni. SNR was decreased average 19.07%, CNR was average decreased 18.17% using 3 filters. In conclusion, Ni filtration was considered to be most suitable when considered comprehensive thickness, character, sort of filter, dose reduction and image quality evaluation in DTS.

• The KIPS Transactions:PartA
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• v.12A no.1 s.91
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• pp.7-12
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• 2005

Scattered look-ahead(SLA) pipelining method can be efficiently used for high-speed or low-power applications of digital II R filters. Although the pipelined filters are guaranteed to be stable by this method, these filters suffer from large roundoff noise when the poles are crowded within some critical regions. An angle and radius constrained II R fille. design approach using modified Remez exchange algorithm and least squares algorithm is proposed to avoid tight pole-crowding in pipelined filters, resulting in improved frequency responses and reduced coefficient sensitivities. Experimental results demonstrate that our proposed method leads to chip area reduction by $33{\%}$ and low power by $45{\%}$ against the conventional method.