• Journal of KIISE:Information Networking
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• v.33 no.2
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• pp.183-192
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• 2006

This paper analyzes the price-selection problem under priority-based scheduling for QoS (Quality of Service) network services, i.e., how to determine the price associated with each service level. In particular, we focus on the problems with the pricing mechanism based on equilibrium analysis. We claim that the assumptions needed to produce equilibrium nay not hold in some important environments. Specifically, (a) the individual user's impact on the system is not infinitesimal and (b) users do not always have up-to-date global system-status knowledge crucial for optimal user decisions required for equilibrium. These may make the equilibrium models inaccurate in realistic environments. We examine the accuracy of some existing equilibrium methods by using a dynamic model that we have developed for system behavior analysis. The analysis indicates that equilibrium methods fail to model accurately the system behavior in some realistic environments.

• Journal of KIISE:Software and Applications
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• v.35 no.1
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• pp.22-32
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• 2008

To overcome the weakness of the image retrieval system using the existing Ontology and the distributed image based on the database having a simple structure, HERMES was suggested to ensure the self-control of various image suppliers and support the image retrieval based on semantic, the mentioned framework could not solve the problems which are not considered the deterioration in the capacity and scalability when many users connect to broker server simultaneously. In this paper the tables are written which in the case numerous users connect at the same time to the supply analogous level of services without the deterioration in the capacity installs Broker servers and then measures the performance time of each inner Broker Component through Monitoring System and saved and decides the ranking in saved data. As many Query performances are dispersed into several Servers User inputted from the users Interface with reference to Broker Ranking Table, Load Balancing system improving reliability in capacity is proposed. Through the experiment, the scheduling technique has proved that this schedule is faster than existing techniques.

• Journal of KIISE:Information Networking
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• v.35 no.1
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• pp.21-33
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• 2008

The wireless sensor nodes near to the fixed sink node suffer from the quickly exhausted battery energy. To address this problem, the mobile sink node has been applied to distribute the energy consumption into all wireless sensor nodes. However, since the mobile sink node moves, the data collection scheduling scheme is necessary for the sink node to receive the data from all sensor nodes as fair as possible. The application fields of wireless sensor network need the real-time processing. If the uneven data collection occurs in the wireless sensor network, the real-time processing for the urgent events can not be satisfied. In this paper, a new method is proposed to support the lair data collection between all sensor nodes. The proposed method performs the scheduling algorithm based on the resident time of the sink node staying in a radius of communication range and the amount of data transferred already. In this paper, the proposed method and existing data collection scheduling schemes are evaluated in wireless sensor network with the mobile sink node. The result shows that the proposed method provides the best fairness among all data collection schemes.

• The Transactions of the Korea Information Processing Society
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• v.1 no.3
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• pp.367-379
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• 1994

This paper describes scheduling algorithms of the UNIX operating system and shows an analytical approach to approximate the average conditional response time for a process in the UNIX operating system. The average conditional response time is the average time between the submittal of a process requiring a certain amount of the CPU time and the completion of the process. The process scheduling algorithms in thr UNIX system are based on the priority service disciplines. That is, the behavior of a process is governed by the UNIX process schuduling algorithms that (ⅰ) the time-shared computer usage is obtained by allotting each request a quantum until it completes its required CPU time, (ⅱ) the nonpreemptive switching in system mode and the preemptive switching in user mode are applied to determine the quantum, (ⅲ) the first-come-first-serve discipline is applied within the same priority level, and (ⅳ) after completing an allotted quantum the process is placed at the end of either the runnable queue corresponding to its priority or the disk queue where it sleeps. These process scheduling algorithms create the round-robin effect in user mode. Using the round-robin effect and the preemptive switching, we approximate a process delay in user mode. Using the nonpreemptive switching, we approximate a process delay in system mode. We also consider a process delay due to the disk input and output operations. The average conditional response time is then obtained by approximating the total process delay. The results show an excellent response time for the processes requiring system time at the expense of the processes requiring user time.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.346-348
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• 2005

무선 통신망은 유선 통신망에 비하여 대역이 한정적이기 때문에 효율적인 대역의 이용은 매우 중요하다. 그러나 802.16 BWA 시스템의 UGS 알고리즘은 보낼 데이터가 없어도 일정한 간격으로 고정 대역을 단말에 계속 할당하기 때문에 대역의 낭비가 심하다. 본 논문에서는 VAd가 가능한 단말에서 UGS 알고리즘을 이용할 때, 보낼 패킷이 없는 경우에는 그 유휴 대역을 이용하여 우선순위가 낮은 nrtPS나, BE 알고리즘을 이용하는 패킷을 대신 전송하는 방법을 제시함으로써, 802.16 BWA 시스템에서 효율적인 상향링크 스케줄링을 구현한다.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.2
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• pp.101-107
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• 2009

In existing wireless ad-hoc networks, how to distribute network resources fairly between many users to optimize data transmission is an important research subject. However, in wireless mesh networks (WMNs), it is one of the research areas to avoid gateway bottleneck more than the fair network resource sharing. It is because WMN traffic are concentrated on the gateway connected to backhaul. To solve this problem, the paper proposes Weighted Fairness Time-sharing Access (WFTA). The proposed WFTA is a priority time scheduling scheme based on Weighted Fair Queuing (WFQ).

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.91-93
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• 2002

본 논문은 RISC CPU인 Intel StrongARM SA-1100을 기반으로 하는 실시간(Real-Time) 운영체제를 설계한 내용을 설명하고 있다. 본 논문에서 구현된 운영체제는 태스크들이 우선순위 기반으로 저리되는 선점형 스케줄링 방식을 채택함으로써 실기간 운영체제의 주요 특징인 시간 결정성(determinism)을 보장하도록 하였다. Intel StrongARM SA-1100은 고성능(High Performance), 저전력(Low Power)의 장점 때문에 모바일(Mobil) 환경에서 많이 사용되고 있다. 본 논문은 Intel StrongARM SA-1100 CPU를 타겟으로 시간 결정성이 보장되도록 멀티 태스킹(Multitasking)과 ITC(InterTasking Communication)를 설계하고 구현한 내용에 대해 설명하고 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.358-360
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• 2002

분산 TMO(Time-triggered Message-triggered Object) 객체그룹은 분산 환경에서 실시간 특성을 지원하는 TMO 객체를 그룹으로 하여 TMO 객체에 대한 보안 관리 및 최적 레퍼런스 선택을 위한 부하고려 바인딩 방안과 여러 클라이언트의 요청 작업에 대한 수행 우선순위 스케줄링 방안을 제공하는 모델이다. TINA(Telecommunications Information Networking Architecture)의 객체그룹 개념을 기반으로 실시간 특성을 자체적으로 가지는 TMO 객체를 그룹으로 하여 특정 ORB나 운영체제에 국한되지 않고 COTS(Commercial Off-The-Shelf) 상에서 보장된 실시간 서비스를 제공한다. 이를 위해 분산 TMO 객체 그룹의 구조를 정의하고, TMO 객체의 관리 서비스와 실시간 서비스 관점에서 객체의 기능과 상호작용을 설명한다. 마지막으로, TMO 객체 관리서비스 관점에서 비중복 TMO 객체와 중복 TMO 객체의 레퍼런스 선택과정을 보이며, 부하정보를 고려한 중복 TMO 객체의 최적 레퍼런스 선택의 수행결과를 보이고 검증한다.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.6
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• pp.365-371
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• 2003

Input queued switch is useful for high bandwidth switches and routers because of lower complexity and fewer circuits than output queued. The input queued switch, however, suffers the HOL-Blocking, which limits its throughput to 58%. To overcome HOL-Blocking problem, many input-queued switch controlled by a scheduling algorithm. Most scheduling algorithms are implemented based on a centralized scheduler which restrict the design of the switch architecture. In this paper, we propose a simple scheduler called Pipelined Round Robin (PRR) which is intrinsically distributed by each input port. We presents to show the effectiveness of the proposed scheduler.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.6
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• pp.506-513
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• 2002

Distributed control systems(DCS) using fieldbus such as CAN have been applied to process systems but it is very difficult to design the DCS while guaranteeing the given end-to-end constraints such as precedence constraints, time constraints, and periods and priorities of tasks and messages. This paper presents a scheduling method to guarantee the given end-to-end constraints. The presented scheduling method is the integrated one considering both tasks executed in each node and messages transmitted via the network and is designed to be applied to a general DCS that has multiple loops with several types of constraints, where each loop consists of sensor nodes with multiple sensors, actuator nodes with multiple actuators and controller nodes with multiple tasks. An assignment method of the optimal period of each loop and a heuristic assignment rule of each message's priority are proposed and the integrated scheduling method is developed based on them.