• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.6
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• pp.261-269
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• 2004

In this paper, an efficient algorithm for computing in the MPEG/audio Layer Ⅲ (MP3) encoder is proposed. The proposed algerian performs a full-band 1024-point FFT by computing 32-point FFT's of 32 subband outputs. To reduce the aliasing caused by the analysis filter bank, an aliasing cancellation butterfly is developed. A major benefit of the proposed algorithm is the computational saving. By using the proposed algorithm, it is possible to save 40~50% of computations for FFT, which results in about 20% reduction of the PAM-2 complexity.

• Proceedings of the IEEK Conference
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• 2000.06d
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• pp.182-185
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• 2000

In this paper, we present a new adaptive filter structure which is based on polyphase decomposition of the filter to be adapted. This structure uses wavelet transform to acquire transform-domain coefficients of the input signal. With this coefficients RLS algorithm is used for adaptation. Particularly, using the polyphase parallel structure, we can trace the system which has very long impulse response with only increasing the subband, and show that computational savings can be achieved. The proposed structure was applied to system identification for performance estimation and compared with fullband adaptive filter.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.7-10
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• 2000

This paper focuses on the development of speech enhancement techniques for hands-free audio terminals, including two major problems : noise cancellation and acoustic echo cancellation. The objective is to find a joint structure to get a near-end speech signal with minimum distortion and low levels of echo and noise. To solve the two problems, a new promising technique is studied and tested in computer simulation conditions.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.545-546
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• 2004

서브밴드 분리에 의한 에코확산 오디오 워터마킹법은 호스트 신호를 특정 주파수 대역으로 분리하고, MPEG 심리음향 모델을 이용하여 각 대역별로 삽입되는 워터마크의 파워를 파라미터 설정 함수에 의하여 설정한다. 여기서, 본 방법의 강인성과 비지각성을 좌우하는 것은 파라미터 설정 함수가 된다. 따라서, 본 연구에서는 최대의 강인성과 최소의 음질 열화를 구현하기 위하여 청취실험을 실시하여 최적의 파라미터 설정 함수 설정방법에 대한 검토를 수행하였다.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06e
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• pp.315-318
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• 1998

본 논문에서는 서브밴드 및 전 대역(full band)으로부터 얻은 특징 벡터를 함께 사용하여 잡음 환경에서 음성인식 시스템의 성능을 향상시키는 방법을 제안하였다. 이는 인식시 잡음에 오염된 대역에서 얻은 특징 벡터를 제거하는데 따른 정보 손실을 막기 위해 전 대역으로부터 얻은 특징 벡터를 함께 이용하며 신호 대 잡음비가 높은 대역을 강조하여 각 모델에 대한 확률 값을 계산한다. 전화망에서 수집된 데이터베이스를 이용하여 인식 실험을 수행한 결과 비교적 넓은 주파수 대역에 걸쳐 분포된 잡음의 경우에도 인식 성능을 향상시킬 수 있었다.

• The Optical Journal
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• s.146
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• pp.41-46
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• 2013

서브밴드 간의 광학천이를 이용한 양자 캐스케이드 레이저는 PN접합형의 반도체 레이저 다이오드와는 다른 동작 원리를 지닌 중적외선 대역의 반도체 레이저다. 실온에서 동작 가능한 유일한 적외선 대역의 반도체 레이저로, 가시선 영역과 비교해 개척 여지가 많은 적외선 영역 전체를 견인하는 핵심 디바이스로 자리 잡을 전망이다. 이번호에서는 양자 캐스케이드 레이저의 동작 원리와 특징, 활성층 구조, 설계, 발진 등에 대해 소개한다. 이 원고는 일본 하마마쓰 광학(Hamamatsu Photonics) 개발본부 레이저 디바이스 개발그룹의 Naota Akikusa, Tadataka Edamura 씨가 월간 OPTRONICS 2013년 5월호에 기고한 내용으로 그린광학의 유정훈 팀장이 번역에 도움을 주었다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10b
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• pp.634-636
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• 2003

본 논문은 마스크 방식의 관심 영역(ROI, Region Of Interest) 부호 설계와 구현에 대하여 제시한다. 관심 영역에 대한 정지 영상 압축 알고리즘은 웨이블릿 변환과 사용자가 지정한 관심 영역을 결합하여 설계하였다. 즉, 사용자가 지정한 관심 영역을 이용하여 관심 영역 마스크를 생성한다. 양자화 과정에서 웨이블릿 계수들을 각 레벨과 서브밴드로 구분하고 생성된 관심 영역 마스크 정보를 이용하여 양자화 과정을 처리하여 부호화한다. 관심 영역에 대하여서는 높은 영상 품질과 그리고 전체 영상에 대하여서는 높은 압축을 동시에 실현시킬 수 있는 마스크 방식의 관심 영역 부호화 알고리즘을 설계하고 구현하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8C
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• pp.529-535
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• 2011

After permission for utilization of TV white space by FCC, a lot of attentions are focused on spectrum sensing, and various spectrum sensing methods have been proposed. However, they do not consider real environment, thus they are hard to achieve the required performance. In this paper, we propose resolutions for the problem which could be occurred in implementation of spectrum sensing module and verify performance of the proposed methods with computer simulation. The first proposed method utilizes channel status information to separate received signal and spurious for reducing false alarm probability caused by system internal spurious. The another proposed scheme is subband normalization method to prevent miss detection caused by multiple narrow band signals with different received signal strength. The simulation results verify that we can prevent false alarm cause by spurious components with the proposed system internal spurious cognition. Moreover, the proposed subband normalization method shows that it could overcome performance degradation caused by received signal strength difference.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.1
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• pp.76-87
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• 2000

Multicarrier DS-CDAM is an effective approach to realize wideband CDMA system in a multipath fading channeal. In this paper, we propose a cinvolutionally-coded overlapped multicarrier DS-CDMA system, and show the performance improvement by comparing with conventional multicarrier DS-CDMA system. We consider the case of 50% overlapping with the adjacent subband to utilize the transmission bandwidth more efficiently. In the proposed multicarrier system, each of the rate 1/M convolutionally-encoded symbols is also 1/R repetition coded and transmitted using overlapped multicarriers and we may obtain the coding gain and frequency diversity effect, simultaneously. We also analyze the possibility of reduction in total MUI by considering a raised-cosine wave-shaping filter having a roll-off factor (0< ${\beta}{\le}1$). It will be shown that the proposed system outperforms the multicarrier DS-CDMA system in $^{[3]}$.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.4
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• pp.16-22
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• 2012

In this paper, the forensic marking algorithm is proposed using psychoacoustic model II and MDCT for high-quality audio. The proposed forensic marking method, that inserts the user fingerprinting code of the audio content into the selected sub-band, in which audio signal energy is lower than the spectrum masking level. In the range of the one frame which has 2,048 samples for FFT of original audio signal, the audio forensic marking is processed in 3 sub-bands. According to the average attack of the fingerprinting codes, one frame's SNR is measured on 100% trace ratio of the collusion codes. When the lower strength 0.1 of the inserted fingerprinting code, SNR is 38.44dB. And in case, the added strength 0.5 of white gaussian noise, SNR is 19.09dB. As a result, it confirms that the proposed audio forensic marking algorithm is maintained the marking robustness of the fingerprinting code and the audio high-quality.