• 한국인터넷방송통신학회논문지
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• 제13권6호
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• pp.275-280
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• 2013

최근 액서스망의 브로드밴드화와 영상기기의 고성능화에 따라 인터넷을 통한 음성, 영상 등의 미디어 정보를 다루는 멀티미디어 서비스가 주목받고 있으며 점차 보급되어 가고 있다. 앞으로 더욱더 영상 기기나 네트워크 환경에 발맞추어 고품질의 영상을 다루고 이용하는 형태가 점점 다양화되고 활용화 되리라 예측된다. 그 중에서도 동영상 부호화 기술 즉, 영상 정보의 압축 부호화 기술은 중심적인 역할을 하는 기술 중의 하나이다. 동영상 부호화 기술은 방대한 정보량을 필요로 하는 영상 신호 중에 포함되어 있는 용장성을 배제하고 적절한 정보량을 디지털 부호로서 효율인 영상 신호를 표현하는 기술로서 발전되어 가고 있다. 따라서 본 연구는 동영상 부호화에서의 모드 선택에 적용하는 코스트 평가 방법을 검토하고 부호화 효율을 최대화하기 위해 방법을 제안 하고자하며 이를 기존 방법과 비교해 우수성을 확인하였다.

• 정보과학회 논문지
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• 제43권2호
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• pp.246-255
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• 2016

OFDMA는 주파수와 시간 축에 따라 융통성 있는 자원 할당이 가능하고, 적응적 변조와 코딩이 가능하기 때문에 다중률 멀티캐스트 전송에 적합하다. 계층적 코딩과 달리 MDC (multiple description coding)는 비디오 스트림을 서브 스트림으로 분해와 재조립이 용이하며, 수신율에 비례하여 비디오 품질도 증가하는 특성을 가지고 있다. OFDMA 무선 또는 이동통신망에서 비디오를 다중률로 멀티캐스트 전송할 때 자원 할당과 전송률에 관한 수학적 모델을 제시하고, 사용자가 느끼는 비디오 품질 인덱스인 MOS (mean opinion score)를 최대화 혹은 비례적 공평성을 극대화하는 스케줄링 방식에 대해, 평균값 분석 방법론을 통해 장기적 관점에서 비교 분석한다. 또한, 제한된 자원 내에서 일부 사용자에게 최저 품질을 보장하는 pruning 알고리즘을 제시하고, 비디오 세션 전 기간 또는 일부 기간에 최적으로 서브 스트림을 분할할 수 있음을 보인다.

• IEIE Transactions on Smart Processing and Computing
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• 제6권2호
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• pp.102-108
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• 2017

Videos for 360-degree virtual reality (VR) systems have a large amount of data because they are made with several different videos from multiple cameras. To store the VR data in limited space or to transmit it through a channel with limited bandwidth, the data need to be compressed at a high ratio. This paper focuses on the compression efficiency of VR videos for good visual quality. Generally, 360-degree VR videos should be projected into the planer format to cope with modern video coding standards. Among various projection schemes, three typical schemes (equirectangular, line-cubic, and cross-cubic) are selected and compared in terms of compression efficiency and quality using various videos.

• 한국위성정보통신학회논문지
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• 제6권2호
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• pp.66-71
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• 2011

본 논문에서는 통합이동위성시스템에서 계층적 부호화 방식의 성능과 효용성에 대한 평가 결과를 제시한다. 통합이동위성시스템의 주요 서비스는 멀티미디어 방송 및 멀티캐스팅 서비스가 될 것이다. 통합이동위성시스템에서, 위성과 보조지상장치는 고품질의 서비스를 제공하기 위하여 서로 협력적으로 동작하도록 되어 있다. 계층적 부호화 방식은 수신기에서 채널의 샅애에 적응할 수 있도록 하는 일종의 수신기에 의해 주도되는 적응형 방식이다. 본 논문에서는 터보부호화 방식을 이용한 계층적 부호화 방식을 소개하고 여러 가지 시나리오에서의 성능을 평가하며, 그 효용성에 대하여 논할 것이다. 본 논문에서 제시된 성능 평가 결과 및 분석 내용은 향후 효율적인 통합이동위성시스템을 설계하는데 활용될 수 있을 것이다.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1994년도 제11회 음성통신 및 신호처리 워크샵 논문집 (SCAS 11권 1호)
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• pp.103-106
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• 1994

Generally we are used to apply waveform coding method obtaining the high quality synthesized speech. But we have to solve the problems, memory capacity and pitch alteration, for applying the waveform coding method to speech synthesis by rule. The former problem is conquered by improving the integrated semiconductor technology, but the latter problem remains. In this paper, we compare the methods that have proposed for pitch alteration in our laboratory until now. These methods are not change properties of vocal tract formants and only altered the pitch halving method, 1.14% for cepstrum analysis method, and 2.36% for hamonics compensated with the phase method.

• ETRI Journal
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• 제42권3호
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• pp.446-458
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• 2020

In this study, an efficient scheme for hiding data directly in partially encrypted versions of high efficiency video coding (HEVC) videos is proposed. The content owner uses stream cipher to selectively encrypt some HEVC-CABAC bin strings in a format-compliant manner. Then, the data hider embeds the secret message into the encrypted HEVC videos using the specific coefficient modification technique. Consequently, it can be used in third-party computing environments (more generally, cloud computing). For security and privacy purposes, service providers cannot access the visual content of the host video. As the coefficient is only slightly modified, the quality of the decrypted video is satisfactory. The encrypted and marked bitstreams meet the requirements of format compatibility, and have the same bit rate. At the receiving end, data extraction can be performed in the encrypted domain or decrypted domain that can be adapted to different application scenarios. Several standard video sequences with different resolutions and contents have been used for experimental evaluation.

• ETRI Journal
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• 제28권5호
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• pp.664-667
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• 2006

We propose an efficient audio transcoding algorithm that can convert audio streams from terrestrial digital television broadcasting service stations to those for terrestrial digital multimedia broadcasting hand-held receivers. The proposed algorithm avoids the complicated psychoacoustic analysis by calculating the scalefactors of the bit-sliced arithmetic coding encoder directly from the signal-to-noise ratio parameters of the AC-3 decoder. The bit-allocation process is also simplified by cascading the nested distortion control loop. Through subjective evaluation, it is shown that the proposed algorithm provides comparable audio quality to tandem coding but it requires much smaller complexity.

• 방송공학회논문지
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• 제12권6호
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• pp.542-554
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• 2007

근래의 무선망 및 인터넷의 초고속화에 따라 풍부한 멀티미디어에 대한 사용자의 요구가 증대되고 있으며, 이동 통신의 활성화 및 DMB(Digital Media Broadcasting)와 같은 통방융합 서비스의 등장으로 여러 네트워크 망을 통해 다양한 성능을 가진 단말로의 멀티미디어 서비스가 이루어지고 있다. 이러한 환경 변화에 따라 비트율을 줄이기 위한 비디오 압축 부호화 기술뿐만 아니라 시변의 전송 조건, 전송망 특성, 다양한 단말 성능, 사용자 선호도 등에 대한 비디오의 적응 기술에 관심이 모아졌으며, 그 결과 ISO/IEC MPEG(Moving Picture Experts Group) 및 ITU-T VCEG(Video Coding Experts Group)의 JVT(Joint Video Team)에서는 비디오 부호화의 스케일러빌러티(scalbility)를 제공하기 위한 SVC(Scalable Video Coding) 표준화를 진행하였다. 본 논문에서는 공간/시간/화질적 스케일러빌러티를 지원하기 위한 SVC의 대표적 표준 기술들에 대해 설명하고, 기존의 단일 계층(single layer) 부호화 방식과 비교하여 SVC의 부가 비트 요구량 및 부호화 효율에 대해 성능 평가를 하였다.

• 한국의료질향상학회지
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• 제9권1호
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• pp.52-64
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• 2002

Background : Coding of principal diagnosis is essential component for producing reliable health statistics. We performed this study to evaluate the current practice of principal diagnoses determination and coding, and to give some basic data to improve coding of principal diagnosis. Method : Nineteen medical record administrators (MRAs) of 3 university hospitals participated in coding principal Dx. from August 1, 2001 to August 31, 2001. From each hospital, 10 medical records of patients with high frequency disease were selected randomly. Each 10 medical records were grouped into three (A. B, C). Then, these 30 medical records were given to each MRAs for coding. At the same time questionnaire was given to each of them. Questions were to prove how they decide and code the principal diagnosis among many current diagnoses; how they decide and code the principal diagnosis when they see irrelevant diagnosis recorded as the principal diagnosis in medical record, when only tentative diagnoses were recorded without final diagnosis, and when different diagnoses were recorded in different sheets of same record. Agreement of coding among 3 hospitals were compared and survey results were analysed with SAS 6.12. Results : Agreement of coding was found in medical records 5-6 of each 10 medical records. Causes of disagreement were as follows. Difference of clinician's opinion from each hospital; mixed use of guideline from KCD-3 and guideline from DRG; difference in 4th digit classification according to the absence of pathology report in the medical record; difference of abbreviations among hospitals. 57.9% of MRAs selected the principal diagnosis recorded by physician, 42.1% of MRAs decided principal diagnosis after consulting to KCD-3 guideline. When there were difficulties in determining the principal diagnosis, 42.1% of MRAs decided principal diagnosis after discussion with the physician, 26.3% after discussion with fellow MRAs. Conclusion : There were differences in codings among hospitals. To minimize the difference, we suggest the development of disease-specific guidelines for coding in addition to the current general guideline such as KCD-3. To do this, Coding Clinic which can produce guidelines is needed.

• 간호행정학회지
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• 제3권1호
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• pp.107-118
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• 1997

This study was designed to obtain basic data for development of evaluation tool which would be needed to measure the outcome of general quality nursing care of individual patient. The purpose of this study was to analyze and classify the outcome indicators of quality nursing care. The 29 articles of quality nursing care and outcome measures were selected coveniently, and analyzed to classify the outcome indicators of quality nursing care using open coding method. The results of this study were as follows: 1. Quality nursing care was defined as level of excellence of nursing care to achieve good patient outcome. 2. The 6 domains of which were health status, satisfaction, self care, patient progress and prognosis, and compliance were identified in outcome indicators of quality nursing care 3. Seven indicators of health status domain which were perceived health status, quality of life, well-being, daily activities, physical-physiological status, psychoemotional status, and social role functioning were identified. 4. Two indicators of satifaction domain which were patient satisfaction and family satisfaction were identified. 5. Three indicators of self care domain which were skill, knowledge, and home management were identified. 6. Seven indicators of patient progress and prognosis domain which were change of clinical status, resolution of nursing diagnosis and problem, days of stay, dicahrge state, recovery state, survival were identified. 7. compliance with therapeutic direction compliance was identified as an indicator of compliance domain. 8. It was sugested that studies for development of evaluation tools for outcomes of quality nursing the results of this study could be executed