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성영락 한국시뮬레이션학회 1992 한국시뮬레이션학회 논문지 Vol.1 No.1
The DEVS(discrete event system specificaition) formalism specifies a discrete event system in a hierarchical, modular form. DEVSIM++ is a C++based general purpose DEVS abstract simulator which can simulate systems modeled by the DEVS formalism in a sequential environment. This paper describes P-DEVSIM++which is a parallel version of DEVSIM++ . In P-DEVSIM++, the external and internal event of DEVS models can by processed in parallel. For such processing, we propose a parallel, distributed optimistic simulation algorithm based on the Time Warp approach. However, the proposed algorithm localizes the rollback of a model within itself, not possible in the standard Time Warp approach. An advantage of such localization is that the simulation time may be reduced. To evaluate its performance, we simulate a single bus multiprocessor architecture system with an external common memory. Simulation result shows that significant speedup is made possible with our algorithm in a parallel environment.
시간적인 지역성을 이용한 실시간 태스크들의 전력을 고려한 스케줄링
성영락 국민대학교 생산기술연구소 2004 공학기술논문집 Vol.27 No.-
Many real-time tasks have a limited number of operation states which changes with temporal continuity. This paper proposes a novel dynamic voltage scaling algorithm, called TLDVS, for real-time tasks in order to exploit the temporal locality. TLDVS achieves significant energy savings while still preserving timeliness guarantees made by real-time scheduling. Time budgets for each task are divided into two parts. Then the task executes at the lowest attainable frequency/voltage level in the first part. If the task does not complete until the end of the first part, then the scheduler is invoked and increases the processor frequency and voltage to complete the remaining computation load with the remaining time budgets. Simulation results show that TLDVS provides up to 25% of additional energy savings.
온라인 게임을 위한 이 단계 주 메모리 데이터베이스 시스템
성영락 국민대학교 생산기술연구소 2003 공학기술논문집 Vol.26 No.-
In this paper, a main memory database management system for online games is proposed. An online game system is composed of several game servers and a single database server. Since all database operations are concentrated to the database server, the database server is a major bottleneck of online game systems. A main memory database management system employs RAM rather than hard disks as its storage media. Accordingly, the execution speed can be drastically enhanced. The proposed main memory database management system is composed of two layers: the game server main memory database management system and the database server main memory database management system. By using the proposed scheme, the communication cost between the database server and game servers as well as the disk I/O cost of the database server can be substantially reduced.
성영락 국민대학교 생산기술연구소 2002 공학기술논문집 Vol.25 No.-
In this paper, a RAID level 5 system is modeled by using the DEVS formalism. The system consists of one MPU and two PCI buses. For accurate evaluation of RAID system performance, modeling of the PCI bus and MPU are crucial. In the PCI bus model, start and end of message transfer are precisely modeled to measure the bus transfer time. The MPU model specifies the RAID software algorithm as well as the hardware architecture. Several input patterns are applied for verifying the modeling results.
병렬 DEVS 시뮬레이션 환경(P-DEVSIM ++) 성능 평가
성영락 한국시뮬레이션학회 1993 한국시뮬레이션학회 논문지 Vol.2 No.1
Zeigler's DEVS(Discrete Event Systems Specification) formalism supports formal specification of discrete event systems in a hierarchical , modular manner. Associated are hierarchical, distributed simulation algorithms, called abstract simulators, which interpret dynamics of DEVS models. This paper deals with performance evaluation of P-DEVSIM ++, a parallel simulation environment which implements the DEVS formalism and associated simulation algorithms in a parallel environment. Performance simulator has been developed and used to experiment models of parallel simulation executions in different conditions. The experimental result shows that simulation time depends on both the number of processors in the parallel system and the communication overheads among such processors.
원소 밀집을 이용한 원소오토마타 모델의 병렬 시뮬레이션
성영락(Seong Yeong Rak) 한국정보처리학회 1998 정보처리학회논문지 Vol.5 No.4
This paper proposes a scheme to exploit SIMD parallelism in the simulation of Cellular Automata models. The basic idea is to increase the utilization of an ALU in the underlying computer and to reduce simulation time by exploiting the parallelism. Thus, several cells are packed into a computer word and transit their state together. To show the performance of the proposed simulation scheme, two Cellular Automata models are simulated under three distinct hardware environments. The results show considerably high simulation speed-up for every case. Especially, the simulation speedup with the proposed simulation scheme reaches nearly 20 times in the best case.
하이퍼큐브 환경에서의 DEVS 모델의 병렬 시뮬레이션을 위한 매핑
성영락(Yeong Rak Seong),김탁곤(Tag Gon Kim),박규호(Kyu Ho Park) 한국정보과학회 1995 정보과학회논문지 : 시스템 및 이론 Vol.22 No.10
DEVS(Discrete Event Systems SpecificatIon) 형식론은 이산사건 시스템을 계층적으로 모듈화된 형태로 기술한다. DEVS에서 상태전이는 스케쥴링에 의한 내부사건과 불규칙적으로 도착하는 외부 사건에 의해서 이루어진다. P-DEVSim++는 DEVS 모델들을 위한 병렬 분산 시뮬레이션 환경이다. P-DEVSim++에서는 DEVS의 외부사건 외에 내부사건이 병렬처리 된다. 본 논문에서는 P-DEVSim++을 하이퍼큐브 멀티컴퓨터 환경에서 다중통신 없이 수행할 때 그 병렬성을 이용하기 위한 DEVS 모델의 매핑에 대해서 다룬다. 동시에 발생되는 외부사건에 대해서는 동기화를 위한 오버헤드를 줄이기 위해서 태스크 그래프를 이항트리로 변환하였다. 또 여러 내부사건이 동시에 발생되고 각 내부사건이 여러 외부사건을 야기할 경우에는 전체 하이퍼큐브를 서브큐브들의 집합으로 나누어서 하나의 내부사건과 그에 관련된 외부사건들이 같은 서브큐브에서 처리되도록 하였다. 실험을 통하여 제안된 알고리즘의 성능을 측정하였다. 실험 결과, 파라미터들이 바뀜에 따라, 제안된 매핑 알고리즘은 여러 다양한 매핑을 구하였다. 또, 그 구해진 매핑을 이용하여 계층적으로 모듈화된 이산사건 모델의 분산 시뮬레이션에서의 병렬성을 얻을 수 있었다. The DEVS(Discrete Event System Specification) formalism specifies discrete event systems in a modular, hierarchical manner. Within the formalism, state transition is achieved by scheduled internal events and randomly arrived external events. P-DEVSim++ is a parallel, distributed simulation environment for DEVS models In P-DEVSim++, internal events as well as external events are processed in parallel. This paper addresses mapping of DEVS models to utilize the parallelism of P-DEVSim++ in a hypercube multicomputer environment without multicasting, For simultaneous external events processing, task graphs are transformed into binomial trees to reduce synchronization overhead. Also, when multiple internal events occur simultaneously and each internal event is associated with multiple external events, a hypercube is partitioned into a set of subcubes so that an internal event and the associated external events can be processed in the same subcube. The performance of our algorithm is measured through experimentation The result shows that the proposed mapping algorithm generates diverse mappings against various combinations of system parameters. With the generated mapping, the significant parallelism of distributed simulation of hierarchical, modular discrete event models is achieved.