• 제목/요약/키워드: Model Shaping

검색결과 216건 처리시간 0.02초

HE-AAC 부호화의 저비트율에서 음질향상 기법 (Quality Improvement of Low-Bitrate HE-AAC Encoder)

  • 김정근;이재성;이태진;강경옥;박영철
    • 한국음향학회지
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    • 제27권2호
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    • pp.66-74
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    • 2008
  • 본 논문에서는 HE-AAC (High Efficiency Advanced Audio Coding) 오디오 부호화기의 저주파 대역과 고주파 대역을 담당하고 있는 AAC부호화기와 SBR (Spectral Band Replication) 부호화기에 대해 낮은 비트율에서 효과적인 개선 방법을 제안한다. AAC 부호화기가 담당하는 저주파 대역에서 과도신호가 발생하는 부분의 프리에코를 줄이기 위하여 적용 주파수범위가 저주파 대역 방향으로 선택적으로 확장되는 eTNS (exteded Temporal Noise Shaping) 방법을 고안하였다. 또한 SBR에 의해 부호화되는 고주파 대역에서 톤 성분 복원 시에 잡음층 (Noise floor)이 추가 발생되지 않도록 정현파 모델을 통해 톤을 사전 인지하고 인지된 톤들의 주파수를 QMF 밴드의 중앙으로 재배치하여 성능 향상을 이루었다. 제안한 방법들을 사용하여 복호화한 샘플 음원들에 대해 주/객관적 음질평가를 실시한 결과, 표준 HE-AAC에 비해 향상된 결과를 보여주었다.

UML 활용 영향요인에 관한 탐색적 연구 (A Study on Factors Affecting Users' Utilization of Unified Modeling Language)

  • 한광현;김태웅
    • 기술혁신연구
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    • 제15권1호
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    • pp.115-144
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    • 2007
  • This paper is concerned with figuring out a scheme to facilitate UML utilization through examining the factors which affect the intention to use UML. For this, we conducted a survey of those factors among software engineers in IT service companies. In order to examine the factors affecting the intention to use UML, we developed a model by combining the Technology Acceptance Model and the Innovation Attributes Theory, which have been proved to explain well about the acceptance of new technologies and services. Statistical analysis shows that the subjective norm which is one of social factors has significant influence on the career consequences, and also on the compatibility when the result of UML utilization is demonstrable. The career consequences, the compatibility and the ease of use are found to have significant influence on the usefulness perception of UML utilization, implying that the recognition that one's future career can be affected in the long term by UML utilization is important in shaping how one perceives the usefulness along with the compatibility with one's current task type and the ease of use. The usefulness and the compatibility are evaluated to be the factors that have significant influences on the intention to use UML.

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산업현장의 휴먼에러 예방을 위한 통합적 분석모델의 개발 (Development of a Comprehensive Model for Human Error Prevention in Industrial Fields)

  • 이관석;임현교;장성록;이광원;김유창
    • 대한인간공학회지
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    • 제27권1호
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    • pp.37-43
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    • 2008
  • A lot of models have been developed for prevention of human errors. Nevertheless most of them failed to attract attention of industry which has been looking for an integrative model that can show practical countermeasures as well as causal factors of human errors. This research aimed to develop a comprehensive model that can mainly be applied to industrial fields. Therefore, in the model, it was tried to explain sequences of an operator's information process that might cause human errors on one hand, and life cycle stages of facilities involved when human errors occur on the other hand. This model was validated by using a typical accident case. With the comprehensive model presented in this research, one could follow up the sequence of human errors caused by operators, and errors made at the design stage which might cause accidents could be tracked. As a consequence, it is expected that much attention would be paid to preventing human errors in industrial fields since safety personnel can easily find out cause of human errors throughout life cycle stages of man-machine facilities if utilizing the suggested model.

백래쉬가 존재하는 비선형 불확실 시스템의 외란관측기를 이용한 제어 (Control of Nonlinear Uncertain System with Backlash by Disturbance Observer)

  • 홍성일;양진모
    • 한국군사과학기술학회지
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    • 제11권2호
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    • pp.125-135
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    • 2008
  • Backlash in the actuator is one of the most important nonlinearities that limit the performance of speed and position control of mechanical systems. In this paper, we propose disturbance observers in order to estimate the effect of nonlinearities and cancel them subsequently. As a result the disturbance observers make the nonlinear system behave linearly. And finally we show that the disturbance observers guarantee the system robustness and the performance to reject the effect of backlash in the face of parameter uncertainties.

이동 통신을 위한 시간선택성 다중경로 페이딩 채널 모델의 특성 평가 (Characteristics Analysis of the Time Selective Multipath Fading Channel Model for Mobile Communication)

  • 박수진;고석준;이경하;최형진
    • 한국통신학회논문지
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    • 제26권5A호
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    • pp.836-845
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    • 2001
  • 본 논문에서는 시간 선택성 다중경로 이동 무선 채널을 다양한 방법으로 모델링 하고 그에 따른 여러 가지 특성평가를 제시하였다. 모델링 방법에는 Jakes 방식과 시간 영역에서 독립적인 두 개의 가우시안 잡음 발생기와 정형필터(shaping filter)를 사용하는 방식 및 주파수 영역에서 필터링 하는 방식이 있다. 이 세 가지 모델링 방법의 성능을 진폭의 자기상관함수, 상호상관함수, 누적분포함수(Cumulative Distribution Function), 레벨 교차율(Level Crossing Rate), 평균 페이딩 지속 시간(Average Duration of Fades), 위상차의 확률 밀도, 위상차의 자기상관함수 등의 측면에서 시뮬레이션하고 그 결과치와 이론치 간의 특성 비교를 제시하였다. 특히, 확산 대역 시스템을 고려했을 때 이상적인 채널 추정을 가정한 레이크 수신기에서의 BER 성능을 다중경로 개수에 따라 보임으로써 여러 가지 채널 모델링 중에서 주파수 영역에서 필터링 하는 방식이 이동 무선 채널을 모델링 하는데 있어 가장 적합하다는 것을 보였다. 마지막으로 비대칭 도플러(Doppler) 스펙트럼을 모델링 하는 것도 주파수 영역에서 필터링 하는 방식이 편리하다.

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OUTAGE PROBABILITY ANALYSIS OF OC-CDMA SYSTEM WITH IMPERFECT POWER CONTROL UNDER DIFFERENT VELOCITY USERS

  • Panya, Muangruen;Junnapiya, Somyot;Techotchawan, Amnouy;Kidakorn, Pongjai;Omsin, Somchai
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2004년도 ICCAS
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    • pp.480-483
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    • 2004
  • This paper, we present the evaluation of outage probability on the SNR under the overlapped carrier allocation scheme in the reverse link with imperfect power control of a cellular CDMA system, which is base on using Gaussian approximation. In numerical results, the band limited pulse generated by square-root of raised consin pulse shaping filters (SRRC) of the transmitted signal is investigated and compared in conventional FD/CDMA and OC-CDMA of the outage probability. It will be also show that the outage probability can be improved by overlapping of carriers. We use error statistics to model the intra-cell interference and evaluate the impact of different mobiles velocity and number of resolvable paths on the system performance.

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$H_{\infty}$ 제어기를 이용한 공기압 구동시스템의 위치제어 성능 향상에 관한 연구 (High Speed Positioning of a Pneumatic Control System with a $H_{\infty}$ Controller)

  • 장지성
    • 동력기계공학회지
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    • 제2권2호
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    • pp.67-72
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    • 1998
  • To improve control performance, especially positioning speed, of a pneumatic positioning system, dynamic characteristics of a control valve should be considered. In case we design controller including dynamic characteristics of a control valve, it's not easy to design controller gain using simple state feedback because degree of a control system is increased. This study designed controller using loop shaping of $H_{\infty}$ control theory for a model composed of a pneumatic actuator and a control valve, and positioning experiment using this controller was performed. As a result, it was verified that the controller is useful for high speed positioning of a pneumatic positioning system.

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An Analysis of the New Trade Regime for State-Owned Enterprises under the Trans-Pacific Partnership Agreement

  • Yun, Mikyung
    • East Asian Economic Review
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    • 제20권1호
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    • pp.3-35
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    • 2016
  • This paper analyses the new discipline on state-owned enterprises contained in the recently concluded Trans Pacific Partnership Agreement, and evaluates various factors that influenced the shaping of its specific rules. The new discipline consolidates and strengthens related provisions in current trade regimes, reflects various aspects of trade disputes between China and the US, and adopts, as its general underlying rationale, the principle of competitive neutrality. The new discipline contains elements that may challenge the multilateral trade regime, and may serve as a role model in regulating state-owned enterprises, including subsidies in services trade in other on-going trade negotiations. The new regime makes us think hard about fundamental issues regarding enforcement of competition policy against state-owned enterprises, treatment of non-market economies, and how to deal with effects of subsidies in international trade, bringing competition issues back on the trade agenda.

An Input Current Waveshaping AC-DC Converter for Rectifier Loads

  • Singh, Bhim;Garg, Vipin;Bhuvaneswari, G.
    • Journal of Power Electronics
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    • 제8권1호
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    • pp.1-9
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    • 2008
  • This paper presents the design and analysis of a new input AC current wave shaping AC-DC converter for cost effective harmonic mitigation under varying loads. The proposed converter consists of a delta-polygon connected autotransformer based twelve-pulse AC-DC converter and a small rating passive shunt filter tuned at $11^{th}$ harmonic frequency. The proposed AC-DC converter eliminates the most dominant $5^{th},\;7^{th}$ and $11^{th}$ harmonics and reduces higher order harmonics; thereby, resulting in an improved power quality at AC mains. Moreover, the design of the autotransformer is modified to make it suitable for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. To validate the proposed approach, various power quality indices are presented under varying loads. Experimental results obtained on the developed converter are given to validate the model and design of the proposed converter.

동시공학의 제 요인들이 제품개발의 효율성에 미치는 영향 (The Effect of Factors in The Concurrent Engineering on the Efficiency of the Product Development Processes)

  • 손달호
    • 한국경영과학회지
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    • 제21권3호
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    • pp.89-108
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    • 1996
  • During the whole product design and development processes, the concurrent engineering relies on strong and permanent interactions between the departmental functions. Concurrent or simultaneous engineering in new product development is a new concept which needs to be redefined. This paper deals with a concurrent engineering model which represents how concurrency, as an organizational process, is related to a interfunctional project team. Four dimensions shaping the sucess of the concurrent engineering are suggested with detailed meausrement instruments. Moreover, an empirical study on the effects of the four dimensions on the efficiency of the product development processes is carried out in the field of electronic industries.

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