• 한국통신학회논문지
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• 제30권7A호
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• pp.611-619
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• 2005

본 논문은 IEEE 802.16e 기반의 TDD-OFDMA 하향 링크에서의 수율 공평성 및 서비스 커버리지 보장을 위한, WFS(weighted Fair scheduling) 알고리즘과 TGS(Throughput Guarantee Scheduling) 알고리즘을 제안하고, RR(Round Robin), PF(Proportional Fair), FFTH(Fast Fair Throughput), FTH(Fair Throughput) 스케줄링 알고리즘과의 비교를 통한 성능 분석을 수행하였다. 제안된 알고리즘의 성능은 64 kbps와 128 kbps 의 두 개의 최소 사용자 수율 요구 조건에서의 서비스 커버리지, 유효 섹터 수율, 공평성 평가를 통하여 분석되었다. 상대적으로 낮은 64 kbps 요구 조건에서, 제안된 알고리즘은 lxEV-DV 공평성 기준을 만족시키면서, 기존의 스케줄링 방식들보다 서비스 커버리지 내의 가용 사용자 수를 증가시켰다. 또한 128 kbps 요구 조건에서는 PF 스케줄링 방식에 비하여 유효 섹터 수율의 손실이 거의 없이, 서비스 커버리지를 증가시킬 수 있음을 보였다.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1997년도 춘계 학술대회 발표집
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• pp.93-99
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• 1997

Most of the past studies on FMS scheduling problems may be classified into two classes, namely off-line scheduling and on-line scheduling approach. The off-line scheduling methods are used mostly for FMS planning purposes and may not be useful real time control of FMSs, because it generates solutions only after a relatively long period of time. The on-line scheduling methods are used extensively for dynamic real-time control of FMSs although the performance of on-line scheduling algorithms tends vary dramatically depending on various configurations of FMS. Current study is about finding a better on-line scheduling rules for FMS operations. In this study, we propose a method to create priority functions that can be used in setting relative priorities among jobs or machines in on-line scheduling. The priority functions reflect the configuration of FMS and the user-defined objective functions. The priority functions are generated from diverse dispatching rules which may be considered a special priority functions by themselves, and used to determine the order of processing and transporting parts. Overall system of our work consists of two modules, the Priority Function Evolution Module (PFEM) and the FMS Simulation Module (FMSSM). The PFEM generates new priority functions using input variables from a terminal set and primitive functions from a function set by genetic programming. And the FMSSM evaluates each priority function by a simulation methodology. Based on these evaluated values, the PFEM creates new priority functions by using crossover, mutation operation and probabilistic selection. These processes are iteratively applied until the termination criteria are satisfied. We considered various configurations and objective functions of FMSs in our study, and we seek a workable solution rather than an optimum or near optimum solution in scheduling FMS operations in real time. To verify the viability of our approach, experimental results of our model on real FMS are included.

• 한국컴퓨터산업학회논문지
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• 제3권8호
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• pp.989-998
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• 2002

일괄 수용 서비스 스케줄링에서의 배칭(Batching) 기법은 서비스를 요청한 사용자들을 일정 시간 동안 그룹화하여 한꺼번에 서비스하기 때문에 서비스 개시를 위한 지연시간이 발생한다. 그러나 이 지연시간을 효과적으로 제어하지 못하면 대기시간의 불규칙으로 서비스 공정성이 저하되고, 서비스 취소가 발생할 수 있다. 본 논문에서는 기존의 배칭(Batching) 기법인 선입 선출(FCFS) 및 빈도수 우전 방식(MQL)에서 문제시되던 평균 대기시간의 증가, 비 인기 비디오의 서비스 지연 문제를 해결하기 위한 리그 배칭 정책을 제안한다. 본 스케줄링 정책의 개념은 사용자의 요구와 파티션 디스크의 서비스 형태를 감안한 리그를 기초로 한다. 이를 시뮬레이션 한 결과, 기존의 방식들에 비하여 서비스 평균 지연 시간을 약 18% 정도 단축된 향상된 결과를 보임을 입증하였다.

• 한국통신학회논문지
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• 제32권9A호
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• pp.878-887
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• 2007

본 논문은 HSDPA시스템에서 높은 전송 수율을 내면서도 기존 알고리즘에 비해 높은 공평성을 보장하는 스케줄링 알고리즘을 제안한다. 이 알고리즘은 할당하는 채널의 개수를 기지국에 수신된 SIR값에 매겨진 등급에 따라 다르게 할당하고 남는 채널을 다른 사용자에게 할당하여 전송 수율도 높으면서도 보다 많은 사용자에게 서비스를 하여 공평성도 향상시키는 기법이다. 실시간 및 비 실시간 데이터의 종류에 따라 전송 수율 및 공평성의 비율을 비교한 결과 기존의 알고리즘인 비례공정 알고리즘에 비해 높은 전송 수율을 보이고 MAX CIR과 유사한 전송 수율을 나타내고 MAX CIR 알고리즘에 비해 높은 공평성을 보여준다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.295-297
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• 2004

In this paper, we explore the streaming environment which adopts the MPEG-4 FGS(Fine Granualarity Scalability) encoding schemes. We investigate the server and client structure to fine the bottleneck of streaming system. After the structures, we propose a novel packet scheduling algorithm which enhances user perceptable playback quality. Experimental results show the performance enhancement of our algorithm, and system require less resources.

• 전기학회논문지
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• 제61권4호
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• pp.629-631
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• 2012

In Cognitive Radio network, spectrum selection scheme is one of a important part to manage idle spectrums efficiently. However, in CR networks, they have to adopt time-varying channel availability to minimize the interference to primary users (PU), and be able to manage spectrum resources efficiently. In this paper, we proposed a modified PF scheduler which can be appropriate to schedule downlink CR users and channels, by considering the fairness and the throughput as well as the primary user characteristics of each channel.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.197-198
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• 2008

In this paper, we study an opportunistic scheduling scheme for the OFDMA system with streaming services. The service is modeled by using the appropriate utility function. We formulate a stochastic optimization problem that aims at maximizing network utility while satisfying the QoS requirement of each user. The problem is solved by using the dual approach and the stochastic sub-gradient algorithm.

• 한국컴퓨터정보학회논문지
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• 제20권9호
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• pp.61-66
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• 2015

We investigate rate scheduling and power allocation problem for a delay constrained CDMA systems. Specifically, we determine an energy efficient scheduling policy, while each user maintains the short term (n time slots) average throughput. More importantly, it is shown that the optimal transmission strategy for the uplink is same as that of the downlink, called uplink and downlink duality. We then examine the performance of the optimum transmission strategy for the uplink and the downlink for various system environments.

• 경영과학
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• 제15권2호
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• pp.201-210
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• 1998

Truck dispatching is one of the most commonly occurring problems of transprot management. We developed an interactive decision support system named IDSSTD, for the truck dispatching problem where two conflicting objectives are treated and travel speed varies depending on the passing areas and time of day. The IDSSTD aids the decision-making process by allowing the user to interact directly with the database, to direct data to a decision model, and to portray results in a convenient form. The IDSSTD is consisted of two major interactive phases. The pre-scheduling interactive phase is to reduce the complexity of a given problem before applying the BC-saving heuristic algorithm and the post-scheduling interactive phase is to improve practically the algorithmic solution. The IDSSTD has the capabilities of its own manipulation(analysis and recommendation) and diverse graphic features in order to facilitate a user's interaction.

• 산업공학
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• 제23권2호
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• pp.193-202
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• 2010

The quality of service(QoS) model should be presented with the optimal network design to effectively provide the multimedia data services between users and converged services with mobile or TV in the next-generation Internet. In specific, the method to provide differentiated services for each user is needed in the given Internet node to offer the previously negotiated QoS with the user. In this paper, the performance of the QoS enabling technologies in the differentiated services(DiffServ) network domain is analyzed. The QoS offering model and QoS metrics are presented to analyze the performance of the major scheduling algorithms. Under the real network topology and virtual service scenarios in the university, the NS-2 network simulation based on the discrete-event is performed. The results show that the ratio-based scheduling method is more effective rather than the bandwidth-assignment method.