• 전기학회논문지
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• 제59권4호
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• pp.831-840
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• 2010

In this paper, we propose a hearing impairment simulator considering reduced frequency selectivity and asymmetrical auditory filter of the hearing impaired, and we verified the reduced frequency selectivity and asymmetrical auditory filter affected in speech perception through experiments. The reduced frequency selectivity has made embodied by spectral smearing using LPC(linear prediction coding). The shapes of auditory filter are asymmetrical different with each center frequency. Hearing impaired person which has hearing loss was differently changed with that of normal hearing people and it has different value for speech of quality through auditory filter. The experiments confirmed subjective test and objective test. The subjective experiments are composed of 4 kinds of tests: pure tone test, SRT(speech reception threshold) test, and WRS(word recognition score) test without spectral smearing, and WRS test with spectral smearing. The experiment of the hearing impairment simulator was performed from 9 subjects who have normal ears. The amount of spectral smearing was controlled by LPC order. The asymmetrical auditory filter of proposed hearing impairment simulator was simulated and then some tests to estimate the filter's performance objectively were performed. The objective experiment as simulated auditory filter's performance evaluation method used PESQ(perceptual evaluation of speech quality) and LLR(log likelihood ratio) for speech through auditory filter. The processed speech was evaluated objective speech quality and distortion using PESQ and LLR value. When hearing loss processed, PESQ and LLR value have big difference according to asymmetrical auditory filter in hearing impairment simulator.

• 한국음향학회지
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• 제21권6호
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• pp.531-542
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• 2002

본 논문에서는 AMR과 EVRC 음성 부호화기간의 비탠덤 (Tandemless) 방식을 이용한 상호 부호화 방법이 제안되었다. 제안된 방법은 기존의 탠덤 (Tandem) 방식의 상호 부호화 방법과 달리 음성 신호를 다시 복호화했다가 부호화하지 않고, CELP 계열의 음성 부호화기들이 공통적으로 사용하는 파라미터들을 직접 변환한다. 상호 부호화는 LSP 변환, 적응 코드북을 위한 피치 지연 값 및 적응 코드북 이득 변환, 고정 코드북 벡터 및 고정 코드북 이득 변환으로 구성되어 있다. 제안된 방법을 객관적, 주관적 방법으로 평가한 결과 기존의 탠덤 방식에 비하여 적은 계산량과 지연 시간으로 탠덤 방식과 최소 동등, 혹은 우월한 음질을 얻을 수 있다는 것을 확인했다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권5호
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• pp.1108-1130
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• 2013

Wireless Body Area Networks (WBANs) are becoming increasingly important to solve the issue of health care. IEEE 802.15.6 is a wireless communication standard for WBANs, aiming to provide a real-time and continuous monitoring. In this paper, we present our development of a modified Markov Chain model and a backoff model, in which most features such as user priorities, contention windows, modulation and coding schemes (MCSs), and frozen states are taken into account. Then we calculate the normalized throughput and average access delay of IEEE 802.15.6 networks under saturation and ideal channel conditions. We make an evaluation of network performances by comparing with IEEE 802.15.4 and the results validate that IEEE 802.15.6 networks can provide high quality of service (QoS) for nodes with high priorities.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2010년도 추계학술발표논문집 1부
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• pp.402-405
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• 2010

본 논문에서는 소스 코드에 자주 나타나는 코딩 패턴을 자동으로 추출하기 위하여 소스 코드를 분석하고 특성을 평가한다. 기존에 소스 코드에 대한 패턴 마이닝을 이용한 코딩 패턴 감지 방법이 제안되었지만, 수동으로 조사 가능한 코딩 패턴의 수는 한정되어 있기 때문에 대규모 소프트웨어 등에 대한 충분한 분석은 할 수 없었다. 따라서 본 논문에서는 개발자가 분석하고자 하는 코딩 패턴에 대한 자동 추출을 목표로 코딩 패턴의 특성 평가 지표를 선정하여 소스 코드에 대한 분석을 수행한다.

• 한국컴퓨터정보학회논문지
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• 제3권3호
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• pp.99-106
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• 1998

본 논문에서는 탐색영역 제한방식과 스케일링 방식을 이용하여 프랙탈 부호화시에걸리는 시간을 줄이는 방법으로서 영상통신을 위한 새로운 프랙탈 부호화 기법을 제안한다.먼저, 원영상을 스케일링 방식을 이용해 이분의 일과 사분의 일의 크기를 가지는 영상으로축소한다. 이어서, 이분의 일의 크기를 가지는 레인지 블럭들 중에 사분의 일의 크기를 가지는 도메인 블럭과 가장 유사한 블럭을 탐색영역 제한방식을 이용해 검색하게 된다. 실험 결과, 제안된 알고리즘은 Jacquin의 방법에 비해 복원된 영상의 화질은 약간 떨어졌으나, 압축율이 향상되고 부호화 시간을 크게 감소시킬 수 있었다.

• ETRI Journal
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• 제34권3호
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• pp.474-477
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• 2012

The MPEG-D unified speech and audio coding (USAC) standardization process was initiated by MPEG to develop an audio codec that is able to provide consistent quality for mixed speech and music contents. The current USAC reference model structure consists of frequency domain (FD) and linear prediction domain (LPD) core modules and is controlled using a signal classifier tool. In this letter, we propose an LPD single-mode USAC structure using an adaptive widowing-based transform-coded excitation module. We tested our system using official test items for all mono-evaluation modes. The results of the experiment show that the objective and subjective performances of the proposed single-mode USAC system are better than those of the FD/LPD dual-mode USAC system.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.88-88
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• 2002

Satellite Image archiving system requires large storage and long transmission time. A simple and cheap way of overcoming these limitations is to increase the compression ratio. However this requires a feasibility study for accurate applications. Here, a new still image compression standard is being developed, the JPEG2000. It provides lossless and lossy compression, progressive transmission by pixel accuracy and by resolution, region-of-interest coding, user-defined tiling size, random codestream access and processing etc. In this study, we will briefly introduce the JPEG2000 compression standard which provides a new compression technique based on the wavelet technology and offers better compression ratios, and evaluate the compression ratios of JPEG2000 for satellite image by performing various image quality tests. Also, we will compare brief test result using the commercial remote sensing software.

• 방송공학회논문지
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• 제21권6호
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• pp.929-943
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• 2016

본 논문에서는 인지 화질을 고려하기 위해 S-JND 모델 기반의 율 제어 알고리즘을 제안한다. 제안하는 율 제어 알고리즘은 인간이 가지는 시각 시스템의 특징을 반영하기 위하여 시각적 민감도와 시각적 관심도를 동시에 반영할 수 있도록 제작된 S-JND (Saliency-Just Noticeable Difference) 모델을 사용한다. 율 제어 알고리즘을 통해 비트를 분배하는 과정에서 픽쳐 내에 존재하는 각 CTU (Coding Tree Unit)가 가지는 S-JND threshold를 구한다. 각 CTU의 threshold는 적응적으로 적절한 비트를 분배하는데 사용되고, 따라서 제안하는 비트 분배 모델은 인지 화질을 향상 시킬 수 있다. 제안하는 방법의 성능 검증을 위해서 제안하는 방법을 HM 16.9에 구현하였으며, CTC (Common Test Condition) RA (Random Access), Low-delay B와 Low-delay P의 경우에 Class B와 Class C 영상들에 대해 실험 하였다. 실험 결과, 제안하는 방법은 기존 율 제어 알고리즘 대비 평균 2.3%의 비트율이 감소했고 BD-PSNR은 약 0.07dB 향상이 있었으며 비트 정확도 또한 0.06% 정도 증가하였다. DSCQS (Double Stimulus Continuous Quality Scale) 방법으로 측정한 결과, 제안하는 방법은 기존 방법 대비 0.03 MOS (Mean Opinion Score) 향상을 보였다.

• 전기학회논문지
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• 제60권6호
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• pp.1196-1203
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• 2011

The reduced frequency selectivity is a typical phenomenon of sensorineural hearing loss. In this paper, we compared two modeling methods for reduced frequency selectivity of hearing impaired people. The two models of reduced frequency selectivity were made using LPC(linear prediction coding) algorithm and bandwidth control algorithm based on ERB(equivalent rectangular bandwidth) of auditory filter, respectively. To compare the effectiveness of two models, we compared the result of PESQ (perceptual evaluation of speech quality) and LLR(log likelihood ratio) using 36 Korean words of two syllables. To verify the effect on noise condition, we mixed white and babble noise with 0dB and -3dB SNR to speech words. As the result, it is confirmed that the PESQ score of bandwidth control algorithm is higher than the score of LPC algorithm, on the other hands, and the LLR score of LPC algorithm is lower than the score of bandwidth control algorithm. It means that both non-linearity and widen auditory filter characteristics caused by reduced frequency selectivity could be more reflected in bandwidth control algorithm than in LPC algorithm.

• 국제초고층학회논문집
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• 제9권2호
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• pp.197-212
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• 2020

In this study, POE(Post Occupancy Evaluation) evaluation indexes were selected into six categories through the consideration of theories and prior research. Therefore, qualitative supply can be achieved through POE according to the aspect of residential environment after the quantitative supply of mixed-use apartment complex by the population concentration in Seoul due to industrialization and urbanization. As the evaluation elements, detailed survey contents were selected for livability, convenience, comfort, safety, economy, and sociality. Based on the survey contents, six elements were evaluated and analyzed using Data coding and Likert scale after surveying 12 complexes (Urban areas and non-urban areas) in Seoul. As a result of the study, six categories selected as the POE showed that importance of quality of life and safety was developed in high recognition according to high satisfaction with convenience and safety. Sociality showed the lowest satisfaction in the following order : livability, comfort, economy and sociality. Residents' sense of community, interaction with neighborhood, etc., showed low satisfaction, and it seems that it is necessary to improve and supplement the system for the development of mixed-use apartment complex in the future. The detailed characteristics of livability showed high satisfaction of the living room, the front door and the main room which are main uses of housing, and low satisfaction in storage size. The analysis of convenience is that convenient public transportation was the highest, and educational environment and additional facilities were the lowest, showing the advantages and disadvantages of location characteristics. As a result of the analysis of comfort, satisfaction with the landscape area was low and it seems that green space is needed for the development of mixed-use apartment complex in the future. Lastly, regarding the safety, the satisfaction of the access control, the location of security office, etc. were high, however separation of circulation was low. Therefore, it is necessary to clearly separate the circulation between the residence and other facilities in the mixed-use apartment complex.