• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.8
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• pp.1190-1200
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• 1993

In this work, the performance of both delay sensitive traffics and loss sensitive traffics of the output buffered ATM switch with priority control mechanisms has been evaluated. We choose the partial buffer sharing mechanism as the loss priority control mechanism and the HOL(Head Of Line) priority control mechanism as the time priority control mechanism. We model loss sensitive traffics with Poisson process and delay sensitive traffics with MMPP. With loss priority control, it is confirmed that loss probability of loss sensitive traffice decreases when the loss priority control mechanism is chosen. With time priority control, it has also been confirmed that mean cell delay of delay sensitive traffics decreases when the HOL priority control mechanism is used. From this analysis, It has been confirmed that the requirements of QOS for both loss sensitive and delay sensitive traffics can be satisfied in the ATM switch by combining both the loss priority control mechanism and the HOL priority control mechanism.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.691-693
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• 1999

이동 컴퓨팅 환경은 유선망에 비하여 대역폭이 낮고, 호스트의 성능이 낮으며, 사용자의 이동에 따른 여러 가지 문제점이 나타난다. 이러한 이동 컴퓨팅 환경에서 멀티미디어 서비스를 제공하기 위해서는 무엇보다 QoS 제어가 중요하다. 따라서 본 논문에서는 이동 멀티미디어 컴퓨팅 환경의 동적 변화에 적응하고, 효율적으로 QoS를 제어하기 위하여 동적 우선순위를 기반으로 한 QoS 제어 기법을 제시한다. 동적 우선순위는 최초 연결성정 시에 결정되는 정적 우선순위와 보상을 기반으로 한 대역폭 변화값에 따라 결정되며, QoS 제어를 위한 기준으로 사용된다. 이러한 동적 우선순위는 낮은 QoS를 제공받은 MH(Mobile Host)가 핸드오프를 수행하여 새로운 셀로 이동한 경우에도 지속적으로 낮은 QoS를 제공받는 문제를 해결함으로써 공평하게 대역폭을 할당하는 장점이 있다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.78-83
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• 2004

Currently used DLC(Direct Load Control) algorithm is only focused on ON/OFF load control not concerning about reliving participated customer's inconvenience and load priority. Therefore, that is a major obstacle to attract customer participating in demand response program. To overcome the above defects, the authors represent direct load control algorithm using priority based dynamic programming. the proposed algorithm is that participant customer send E-mail to DLC center about priority of load before executing DLC, then DLC algorithm decide which load to be OFF by using priority and off time constraint of the load. By using dynamic programming based on the order of priority for DLC algorithm it is possible to maximize participating customer's satisfaction and it will help to attract more customer's participating in demand response program.

• The Journal of the Korea Contents Association
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• v.10 no.7
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• pp.115-121
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• 2010

It always must guarantee preceding process of the transaction with the higher priority in real-time database systems. The pessimistic concurrency control method resolves a conflict through aborting or blocking of a low priority transaction. However, if a high priority transaction is eliminated in a system because of its deadline missing, an unnecessary aborting or blocking of a low priority transaction is occurred. In this paper, the proposed method eliminates a transaction that is about to miss its deadline. And it prevents needless wastes of resources and eliminates unnecessary aborting or blocking of a low priority transaction. It is shown through the performance evaluation that the proposed method outperforms the existing methods in terms of the deadline missing ratio of transactions.

• Journal of the Korea Society of Computer and Information
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• v.5 no.4
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• pp.82-89
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• 2000

This study analyzes the cell loss probability of an ATM multiplexer with real time and non-real time bursty traffics. It is assumed that an ATM multiplexer with loss priority control for the analysis. The loss priority control uses the CLP Reld of cell header. For easy analysis and less computation. the multiplexed traffic of the ATM multiplexer was modeled by the MMDP. The ATM multiplexer is simulated by the MMDP/MMDP/l/K queueing system. From the above results, The connection admission of an ATM multiplexer with loss priority control is determined by the cell loss probability with low priority as well as the size of threshold buffer. Therefore, to increase the statistical multiplexing gain it will be good to utilize the loss priority control in order.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.995-1002
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• 2018

A Contention Access Period(: CAP) with high contention in priority-based MAC protocols can result in higher number of collisions and retransmissions. High-Priority traffic dominates low-priority traffic during CAP depleting low-priority traffic, adversely affecting WBAN throughput, delay, and energy consumption. This paper proposes a Emergency data-First-Priority MAC(: EFP-MAC) superframe structure that is able to reduce contention in the CAP period, and provides a fair chance for low-priority traffic. As a result, the proposed Emergency data-First Priority MAC(; EFP-MAC) The Simulation results show that the proposed MAC achieves lower energy consumption, higher throughput and low latency than the IEEE 802.15.4 standard.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.8
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• pp.1475-1484
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• 1994

In this paper, a priority scheduling algorithm with double threshold and a traffic control mechanism with hysteresis effect are proposed. The double threshold priority scheduling is studied based on HOL and QLT. The hysteresis effect traffic control is specified by hysteresis effect QLT and traffic rate control. According to the simulation results, it can be shown that the proposed dynamic priority scheduling brings better processing performance than the existing QLT algorithm. And the results demonstrate that QLT and traffic rate control with hysteresis effect enhance the performance in comparison with those of single threshold.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.1097-1100
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• 2006

최근 네트워크 기술이 발전하면서 사용자들의 요구가 다양화되고 대용량의 멀티미디어 데이터에 대한 필요성이 증가하고 있다. 실시간성과 동시성이 중요시 되는 멀티미디어 데이터의 전송에는 UDP(User Datagram Protocol)가 사용되고 있는데, UDP는 현재의 인터넷 기반인 TCP (Transmission Control Protocol )와 경쟁관계에 있어 네트워크의 혼잡을 초래하는 경우가 많았다. 또한 TCP 트랙픽은 네트워크의 혼잡제어를 수행하지만 수신자의 관점을 고려하지 않은 점이 있어서 스트리밍 전송에는 적합하지 않은 단점을 가지고 있다. 본 논문에서는 UDP(User Datagram Protocol) 트래픽의 네트워크 형평성 문제를 해결하고 수신자의 관점을 고려하기 위해 네트워크에 우선순위를 적용하여 RTP/RTCP를 기반으로 수신자의 버퍼를 고려한 혼잡제어 알고리즘을 제안하였다. 시뮬레이션 결과를 통해 우선 순위가 있는 네트워크가 우선 순위가 없는 네트워크에 비해 패킷 손실률과 버퍼 점유도 면에서 스트리밍 전송에 적합한 환경을 제공하고 있음을 확인할 수 있었다.

• The KIPS Transactions:PartC
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• v.8C no.6
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• pp.793-805
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• 2001

In the recent priority system, high-priority packet will be served first and low-priority packet will be served when there isn\`t any high-priority packet in the system. By the way, even high-priority packet can be blocked by HOL (Head of Line) contention in the input queueing System. Therefore, the whole switching performance can be improved by serving low-priority packet even though high-priority packet is blocked. In this paper, we study the performance of preemptive priority in an input queueing switch for high speed switch system. The analysis of this switching system is taken into account of the influence of priority scheduling and the window scheme for head-of-line contention. We derive queue length distribution, delay and maximum throughput for the switching system based on these control schemes. Because of the service dependencies between inputs, an exact analysis of this switching system is intractable. Consequently, we provide an approximate analysis based on some independence assumption and the flow conservation rule. We use an equivalent queueing system to estimate the service capability seen by each input. In case of the preemptive priority policy without considering a window scheme, we extend the approximation technique used by Chen and Guerin [1] to obtain more accurate results. Moreover, we also propose newly a window scheme that is appropriate for the preemptive priority switching system in view of implementation and operation. It can improve the total system throughput and delay performance of low priority packets. We also analyze this window scheme using an equivalent queueing system and compare the performance results with that without the window scheme. Numerical results are compared with simulations.

• ICROS
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• v.1 no.3
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• pp.92-100
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• 1995

본 연구에서는 페트리 네트를 사용하여 모델링된 이산 사건 시스템의 제어시 발생하는 충돌 현상을 해결하기 위하여 퍼지 개념을 사용하였다. 이를 통하여 페트리 네트로 시스템을 제어할 경우 발생하는, 큰 문제점인 외부 시스템과의 데이터 입출력 설정의 어려움을 해결하는 방법을 보였다. 또한 제시된 규칙 행렬의 단순성으로부터 쉽게 충돌 현상하의 우선 순위를 변화시킬 수 있다. 시스템을 제어하는 전문가의 지식이 모호하여 단순히 상수값으로 우선순위를 표현할 수 없는 경우에는 퍼지개념을 이용하여 해결하였다. 이러한 방법들은 소규모의 모터 자동 조립 시스템을 제어하는데 부품의 수량, 작업의 대기 상태를 퍼지화하여 규칙행렬을 만들어 제어신호를 발생시켰다. FMS, CIM을 제어할 때 발생하는 Scheduling 문제도 본 논문의 방법을 사용하면 해결할 수 있다고 본다.