• Journal of Information Processing Systems
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• 제8권4호
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• pp.555-566
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• 2012

The cloud environment makes it possible to analyze large data sets in a scalable computing infrastructure. In the bioinformatics field, the applications are composed of the complex workflow tasks, which require huge data storage as well as a computing-intensive parallel workload. Many approaches have been introduced in distributed solutions. However, they focus on static resource provisioning with a batch-processing scheme in a local computing farm and data storage. In the case of a large-scale workflow system, it is inevitable and valuable to outsource the entire or a part of their tasks to public clouds for reducing resource costs. The problems, however, occurred at the transfer time for huge dataset as well as there being an unbalanced completion time of different problem sizes. In this paper, we propose an adaptive resource-provisioning scheme that includes run-time data distribution and collection services for hiding the data transfer time. The proposed adaptive resource-provisioning scheme optimizes the allocation ratio of computing elements to the different datasets in order to minimize the total makespan under resource constraints. We conducted the experiments with a well-known sequence alignment algorithm and the results showed that the proposed scheme is efficient for the cloud environment.

• 조명전기설비학회논문지
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• 제20권6호
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• pp.96-103
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• 2006

서보 드라이브의 성능 향상을 위해 AC 서보 전동기의 MRAC (Model Reference Adaptive Control) 기반 적응 전류 제어 기법이 제시된다. 인버터 구동 전류 제어 기법 중 예측형 전류 제어 기법은 이상적인 과도 응답 및 정상 상태 응답을 주지만, 전동기 파라미터 변화 시 정상상태 응답 성능이 저하된다. 이러한 제한 점을 극복하기 위해 파라미터 변화에 의한 외란이 MRAC 기법에 의해 추정되어 전향 제어에 의해 보상된다. 제안된 방식은 기존의 외란 추정 방식과 달리 관측기 구성을 위한 인버터의 상전압 측정을 필요로 하지 않는다. 제안된 적응 제어 방식의 점근안정성과 효과적으로 서보 드라이브에 적용될 수 있음이 입증된다. 제안된 방식이 DSP TMS320C31을 이용하여 구현되고 유용성이 시뮬레이션과 실험을 통해 입증된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권1호
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• pp.426-445
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• 2012

Conventional rate control (RC) schemes for H.264 video coding usually regulate output bit rate to match channel bandwidth by adjusting quantization parameter (QP) at fixed full frame rate, and the passive frame skipping to avoid buffer overflow usually occurs when scene changes or high motions exist in video sequences especially at low bit rate, which degrades spatial-temporal quality and causes jerky effect. In this paper, an active content adaptive frame skipping scheme is proposed instead of passive methods, which skips subjectively trivial frames by structural similarity (SSIM) measurement between the original frame and the interpolated frame via motion vector (MV) copy scheme. The saved bits from skipped frames are allocated to coded key ones to enhance their spatial quality, and the skipped frames are well recovered based on MV copy scheme from adjacent key ones at the decoder side to maintain constant frame rate. Experimental results show that the proposed active SSIM-based frameskip scheme acquires better and more consistent spatial-temporal quality both in objective (PSNR) and subjective (SSIM) sense with low complexity compared to classic fixed frame rate control method JVT-G012 and prior objective metric based frameskip method.

• 한국통신학회논문지
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• 제32권3A호
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• pp.261-270
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• 2007

실시간과 비실시간 서비스 클래스의 각 QoS요구 사항을 만족하면서 전체 시스템 용량을 최대화하기 위하여 DTPQ스케줄링 알고리즘이 제안된 바 있다. 기존 DTPQ방식은 개별 서비스 클래스의 QoS를 만족하면서 전체 시스템의 평균 수율을 극대화하기 위해 실시간 서비스의 HOL 패킷의 지연 시간이 정해진 임계값을 넘는 경우에만 서비스하는 접근으로서, 이를 구현하기 위해서는 주어진 환경에서 적절한 지연 임계값을 설정할 수 있어야 한다. 본 논문에서는 실시간 사용자의 채널 상태와 지연 시간에 따라 지연 임계값을 적응적으로 적용하는 A-DTPQ 기반의 스케줄링 기법을 제안한다. 이는 기존의 DTPQ알고리즘과 달리 트래픽 부하 및 채널 특성 등에 따라 지연 임계값을 적응적으로 결정하는 방식이다. 시스템 레벨 시뮬레이션을 통해 제안 방식의 고정된 최적 임계값을 가지는 DTPQ방식보다 성능이 향상시킬 수 있음을 확인하였으며, 향후 연구에서는 다양한 서비스 클래스에 대해 이와 같은 개념을 일반화할 수 있을 것이다.

• 제어로봇시스템학회논문지
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• 제9권2호
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• pp.99-106
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• 2003

A new reconfigurable model following flight control method based on direct adaptive scheme is presented. Using the timescale separation principle, both the inner-loop and the outer-loop states are controlled simultaneously. For the timescale separation assumption to be satisfied, the inner-loop model dynamics is set to be fast whereas the outer-loop model dynamics is set to be relatively slow. The stability and convergence of the proposed control law is proved by Lyapunov theorem. One of the merits of the proposed reconfigurable controller is that the FDI process and the persistent input excitation are not necessary, which is suitable for the flight control system. To evaluate the reconfiguration performance of the proposed control method, numerical simulation is performed using six degree-of-freedom nonlinear dynamics.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
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• pp.155-158
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• 2003

This paper proposes a quality-of-service(QoS)-adaptive proxy-switching scheme for multimedia streaming over the Internet. characteristic of multimedia-object about that effect on weight and transport-time causes Streaming Application is restricted to high-quality-service. But using of Proxy or Cache can reduce restraint of media stream. However previous scheme propose only structure of proxy and skill of streaming-object. It couldn't propose proper scheme about limited cache and proxy error occasion. We propose adaptive-proxy-switching mechanism for solution about some problems that caused by single-proxy and limited cache in case of streaming service.

• 품질경영학회지
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• 제32권4호
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• pp.169-183
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• 2004

The synthetic control chart (SCC) proposed by Wu and Spedding (2000) is to detect shifts in the process mean. The performance was re-evaluated by Davis and Woodall (2002), and the steady-state average run length (ARL) performance was shown to be inferior to cumulative sum (CUSUM) or exponentially weighted moving average (EWMA) chart This paper proposes a simple adaptive scheme to improve the performance of the synthetic control chart. That is, once a non-conforming (NC) sample occurs, we investigate the next L-consecutive samples with larger sample sizes and shorter sampling intervals. We employ a Markov chain model to derive the ARL and the average time to s19na1 (ATS). We also propose a statistical design procedure for determining decision variables. Comprehensive comparative study shows that the proposed control chart is uniformly superior to the original SCC or double sampling (DS) Χ chart and comparable to the EWMA chart in ATS performance.

• 대한수학회보
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• 제45권4호
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• pp.781-795
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• 2008

In this paper, we describe the application procedure of the adaptive mesh refinement (AMR) for the weighted essentially non-oscillatory schemes (WENO), and observe the effects of the derived algorithm when problems have piecewise smooth solutions containing discontinuities. We find numerically that the dissipation of the WENO scheme can be lessened by the implementation of AMR while the accuracy is maintained. We deduce from the experiments that the AMR-implemented WENO scheme captures shocks more efficiently than the WENO method using uniform grids.

• Journal of information and communication convergence engineering
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• 제15권1호
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• pp.28-36
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• 2017

The medium access control (MAC) protocol based on dynamic time division multiple access/time division duplex (TDMA/TDD) is responsible for random access control and radio resource allocation in dynamic traffic environments. These functions of random access and resource allocation are very important to prevent wastage of resources and improve MAC performance according to various network conditions. In this paper, we propose new random access and resource allocation schemes to guarantee quality of service (QoS) and provide priority services in a dynamic TDMA/TDD system. First, for the QoS guarantee, we propose an adaptive random access and resource allocation scheme by introducing an access probability. Second, for providing priority service, we propose a priority-based random access and resource allocation scheme by extending the first adaptive scheme in both a centralized and a distributed manner. The analysis and simulation results show that the proposed MAC protocol outperforms the legacy MAC protocol using a simple binary exponential backoff algorithm, and provides good differential performance according to priorities with respect to the throughput and delay.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.320-322
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• 1993

In this paper, the decentralized adaptive control scheme is applied to the control of drum type boiler system. Because the scheme requires the stability of interconnections, static feedback is used to satisfy the requirement of the scheme. From a priori knowledge of the system, system parameter estimates are bounded to prevent parameter drifting. Computer simulation shows that the decentralized adaptive control is suitable for the control of drum type boiler system and robust in the presence of disturbance.