• 대한조선학회논문집
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• 제42권4호
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• pp.411-420
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• 2005

World leading company and research centers have invested much cost and effort into a PLM and digital manufacturing field to obtain their own competitiveness. We have been trying to apply a digital manufacturing, especially simulation to ship production process as a part of PLM implementation for a shipyard. A shipbuilding production system and processes have a complexity and a peculiarity different from other kinds of production systems. So, new analysis and modeling methodology is required to implement digital shipyard. which is a digital manufacturing system for a shipbuilding company. This paper suggests an analysis and simulation modeling methodologies for an implementation of a digital shipyard. New methodologies such as a database-merged simulation, a distributed simulation, a modular simulation with a model library and a 3-tire simulation framework are developed.

• Journal of Communications and Networks
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• 제10권3호
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• pp.258-267
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• 2008

In this paper, we examine what changes the next-generation wireless communication systems will experience in terms of the technologies, services, and networks and, based on that, we investigate how the inter-cell interference management should evolve in various aspects. We identify that the main driving forces of the future changes involve the data-centric services, new dynamic service scenarios, all-IP core access networks, new physical-layer technologies, and heavy upload traffic. We establish that in order to cope with the changes, the next-generation inter-cell interference management should evolve to 1) set the objective of providing a maximal data rate, 2) take the form of joint management of power allocation and user scheduling, 3) operate in a fully distributed manner, 4) handle the time-varying channel conditions in mobile environment, 5) deal with the changes in interference mechanism triggered by the new physical-layer technologies, and 6) increase the spectral efficiency while avoiding centralized coordination of resource allocation of the users in the uplink channel.

• 한국통신학회논문지
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• 제24권6A호
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• pp.803-819
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• 1999

본 논문은 무선 ATM 서비스를 위한 CDMA WATM 시스템을 제시하며, 매체 접속 방식으로 전송 스케줄링과 슬롯 및 무선 링크 할당 알고리즘을 가진 중앙 제어 예약 접속 방식 (CRMA/TSDA)을 제안한다. 또한, 본 논문에서는 CDMA WATM 시스템을 위한 무선 접속 및 링크 제어 방식으로 지역정보 슬롯 및 링크 할당 알고리즘과 광역정보 슬롯 및 링크 할당 알고리즘을 제안하고, 모의 실험을 통하여 양방향 링크에서의 시스템 용량과 성능을 분석하였다. 제시된 접속 방식 및 제어 방식은 기존의 CDMA 랜덤 접속 방식에 비해 만족할 만한 성능을 보이며, ATM 서비스의 요구 품질을 만족시키며 수용할 수 있다. 특히, 지역 정보 제어 방식은 준최적의 광역 정보 방식에 견줄만한 성능을 갖는다.

• 산업경영시스템학회지
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• 제33권3호
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• pp.169-175
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• 2010

Recently, to improve operating efficiency with the higher in-line rate in automated production lines, a lot of cases of grouping machines and material handling system together to form a cluster has shown frequently. This article addresses the job allocation and operation method of automated material handling for cluster-type production systems. First of all, the control problems of the automated material handling systems are classified into the control problem of inter-cluster material handling system and that of intra-cluster material handling system. Then, a distributed agent-based control scheme is proposed for the former, and an operational control procedure for the latter. Simulation experiment shows that the proposed method is efficient in reducing cycle times and improving utilization of material handling vehicles.

• 한국컴퓨터정보학회논문지
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• 제1권1호
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• pp.147-158
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• 1996

본 논문에서는 작업 스케쥴러를 가진 통합된 실 시간 동시성제어 수행 과정을 분석하여 특수화된 데이타 흐름 그래프에 기초로한 동시성 제어구조를 제안하였다. 자료들은 토큰들의 이산 흐름에서 한 노드로부터 다른 노드까지의 연결 호 상에 나타내었다. 또 한 E-R모델에서 알려진 네트워크는 데이타 흐름 그래프로 나타내는 고정적인 문제점을 질의어 토큰을 이용하여 그래프상에 나타내게 하였다 그리고 모든 동시성 제어 기법들은 서로 다른 성능을 비교하여 실험으로 측정하였고, DBFG 스케줄링은 분산 환경에서 2PL보다 뛰어난 성능을 갖는다는 것을 비교 분석하였다.

• 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.

• Journal of Information Processing Systems
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• 제6권4호
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• pp.553-562
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• 2010

The core services in cloud computing environment are SaaS (Software as a Service), Paas (Platform as a Service) and IaaS (Infrastructure as a Service). Among these three core services server virtualization belongs to IaaS and is a service technology to reduce the server maintenance expenses. Normally, the primary purpose of sever virtualization is building and maintaining a new well functioning server rather than using several existing servers, and in improving the various system performances. Often times this presents an issue in that there might be a need to increase expenses in order to build a new server. This study intends to use grid service architecture for a form of server virtualization which utilizes the existing servers rather than introducing a new server. More specifically, the proposed system is to enhance system performance and to reduce the corresponding expenses, by adopting a scheduling algorithm among the distributed servers and the constituents for grid computing thereby supporting the server virtualization service. Furthermore, the proposed server virtualization system will minimize power management by adopting the sleep severs, the subsidized servers and the grid infrastructure. The power maintenance expenses for the sleep servers will be lowered by utilizing the ACPI (Advanced Configuration & Power Interface) standards with the purpose of overcoming the limits of server performance.

• Journal of Information Processing Systems
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• 제13권5호
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• pp.1299-1319
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• 2017

This paper presents a scalable multiple camera collaboration strategy for active tracking applications in large areas. The proposed approach is based on distributed mechanism but emulates the master-slave mechanism. The master and slave cameras are not designated but adaptively determined depending on the object dynamic and density distribution. Moreover, the number of cameras emulating the master is not fixed. The collaboration among the cameras utilizes global and local sectors in which the visual correspondences among different cameras are determined. The proposed method combines the local information to construct the global information for emulating the master-slave operations. Based on the global information, the load balancing of active tracking operations is performed to maximize active tracking coverage of the highly dynamic objects. The dynamics of all objects visible in the local camera views are estimated for effective coverage scheduling of the cameras. The active tracking synchronization timing information is chosen to maximize the overall monitoring time for general surveillance operations while minimizing the active tracking miss. The real-time simulation result demonstrates the effectiveness of the proposed method.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2001년도 춘계학술발표논문집 (상)
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• pp.101-104
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• 2001

데이터베이스에서 트랜잭션의 처리량을 향상시키기 위해서 기존의 문법 위주의 직렬성 이론으로는 단위시간당 처리량을 높이기는 힘든 형편이다. 이를 위하여 이타적 잠금 기법(altruistic locking: AL)은 트랜잭션이 객체를 사용한 다음 더 이상 그 객체를 요구하지 않을 때 다른 트랜잭션들이 그 객체를 로크할 수 있도록 미리 객체에 대한 로크를 해제함으로써 트랜잭션들의 대기시간을 줄이고 처리량을 향상시키기 위한 취지에서 제안된 것이다. 확장형 이타적 잠금(extended altruistic locking: XAL)기법은 AL 을 자취의 확장한 것으로 AL 이 근본적으로 안고 있는 반드시 기부된 객체만을 처리해야 한다는 제약을 완화한 기법이다. 본 논문에서는 분산 데이터베이스 환경하에서 장기 트랜잭션으로 인한 단기 트랜잭션의 대기현상을 최소화하도록 함으로써 동시성 제어의 정도를 높일 수 있는 새로운 확장형 이타적 잠금 기법인 양방향 기부기법(two-way donation locking: 2DL)을 제안하고 기존의 제어기법과 비교하였다. 모의실험에 의한 성능평가 결과 2DL 은 작업 처리율과 트랜잭션의 평균 대기시간 면에서 우수한 결과를 나타내었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권8호
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• pp.3880-3899
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• 2019

Distributive desynchronization algorithms based on pulse-coupled oscillator (PCO) models have been proposed for achieving collision-free wireless transmissions. These algorithms do not depend on a global clock or infrastructure overheads. Moreover, they gradually converge to fair time-division multiple access (TDMA) scheduling by broadcasting a periodic pulse signal (called a 'firing') and adjusting the next firing time based on firings from other nodes. The time required to achieve constant spacing between phase neighbors is estimated in a closed form or via stochastic modeling. However, because these algorithms cannot guarantee the completion of desynchronization in a short and bounded timeframe, they are not practical. Motivated by the limitations of these methods, we propose a practical solution called PD-DESYNC that provides a short and deterministic convergence time using a flag firing to indicate the beginning of a cycle. We demonstrate that the proposed method guarantees the completion of desynchronization within three cycles, regardless of the number of nodes. Through extensive simulations and experiments, we confirm that PD-DESYNC not only outperforms other algorithms in terms of convergence time but also is a practical solution.