• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.46-58
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• 2003

The recent Internet is changing from its best-effort service and needs the network structure and traffic engineering, which can support various applications requiring differentiated traffic processing and high quality of service. The extension of the Internet from wired to wireless system generating location-dependent and burst errors make more difficult to support a good service with the existing packet scheduling algorithm. In this paper, we propose a wireless diffserv packet scheduling (WDSPS) algorithm that can provide reliable service in the differentiated wireless internet service network. The proposed scheduling algorithm solves the HOL(head of line) blocking problems of class queue occurred in wireless network, supports the differentiated service for each class which is defined in differentiated service networks and makes possible the gradual and efficient service compensation not only among classes but also among flows to prevent the monopoly of one class or one flow. Through simulations, we show that our proposed WDSPS scheduling algorithm can provide the required QoS differentiation between classes and enhance the service throughput in various wireless network conditions.

• Journal of KIISE:Information Networking
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• v.41 no.4
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• pp.192-201
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• 2014

User scheduling boosts the Multi-User Multi-Input Multi-Output (MU-MIMO) gain by selecting an optimal set of users to increase the 802.11 Wi-Fi system capacities. Many kinds of user scheduling algorithms, however, fail to realize the advantages of MU-MIMO due to formidable Channel State Information (CSI) overhead. In this paper, we propose a user scheduling method considering such CSI exchange overhead and its MAC protocol, called ACE (Active CSI Exchange based User Scheduling for MU-MIMO Transmission). Unlike most proposals, where user scheduling is performed after an Access Point (AP) receives CSI from all users, ACE determines the best user set during the CSI exchange phase. In particular, the AP broadcasts a channel hint about previously scheduled users, and the remaining users actively send CSI reports according to their Effective Channel Gains (ECGs) calculated from the hint. Through trace-driven MATLAB simulations, we prove that the proposed scheme improves the throughput gain significantly.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.2
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• pp.650-669
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• 2017

Coordinated multiple points transmission and reception (CoMP) technology is used to mitigate the inter-cell interference, and increase cell average user normalized throughput and cell edge user normalized throughput. There are two kinds of radio resource schedule strategies in LTE-A/5G CoMP system, and they are called centralized scheduling strategy and distributed scheduling strategy. The regional centralized scheduling cannot solve interference of inter-region, and the distributed scheduling leads to worse efficiency in the utilize of resources. In this paper, a novel distributed scheduling scheme named 9-Cell alternate authorization (9-CAA) is proposed. In our scheme, time-domain resources are divided orthogonally by coloring theory for inter-region cooperation in 9-Cell scenario [6]. Then, we provide a formula based on 0-1 integer programming to get chromatic number in 9-CAA. Moreover, a feasible optimal chromatic number search algorithm named CNS-9CAA is proposed. In addition, this scheme is expanded to 3-Cell scenario, and name it 3-Cell alternate authorization (3-CAA). At last, simulation results indicate that 9/3-CAA scheme exceed All CU CoMP, 9/3C CU CoMP and DLC resource scheduling scheme in cell average user normalized throughput. Especially, compared with the non-CoMP scheme as a benchmark, the 9-CAA and 3-CAA have improved the edge user normalized throughput by 17.2% and 13.0% respectively.

• Journal of Digital Contents Society
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• v.4 no.2
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• pp.127-137
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• 2003

A Web crawler is an important Internet software technology used in a variety of Internet application software which includes search engines. As Internet continues to grow, implementations of high performance web crawlers are urgently demanded. In this paper, we study how to support dynamic scheduling for a multiprocess-based web crawler. For high performance, web crawlers are usually based on multiprocess in their implementations. In these systems, crawl scheduling which manages the allocation of web pages to each process for loading is one of the important issues. In this paper, we identify issues which are important and challenging in the crawl scheduling. To address the issue, we propose a dynamic crawl scheduling framework and subsequently a system architecture for a web crawler with dynamic crawl scheduling support. This paper presents the design of the Web crawler with dynamic scheduling support.

• Journal of Korea Society of Industrial Information Systems
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• v.8 no.4
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• pp.64-72
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• 2003

A Web crawler is an important Internet software technology used in a variety of Internet application software which includes search engines. As Internet continues to grow, implementations of high performance web crawlers are urgently demanded. In this paper, we study how to support dynamic scheduling for a multiprocess-based web crawler. For high peformance, web crawlers are usually based on multiprocess in their implementations. In these systems, crawl scheduling which manages the allocation of web pages to each process for loading is one of the important issues. In this paper, we identify issues which are important and challenging in the crawl scheduling. To address the issue, we propose a dynamic crawl scheduling framework and subsequently a system architecture for a web crawler with dynamic crawl scheduling support. And we analysed the behaviors of Web crawler. Based on the analysis result, we suggest the direction for the design of high performance Web crawler.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6B
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• pp.377-386
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• 2005

Recently, to increase throughput per hour on real-time disk scheduling, a lot of algorithms that apply SCAN technique to EDF(Earliest Deadline First) that is representative real-time disk scheduling algorithm are studied. However, existing disk scheduling algorithms have several limitations because they consider continuous I/O requests when create SCAN group. Also, because SCAN technique was fixed direction, the existing algorithms have shortcoming that there are a lot of time damages. This paper proposes a new real-time disk scheduling algorithm based on the insertion technique and the two-way SCAN technique to solve the problems of the exiting real-time disk scheduling algorithms in hard real-time system. The simulation result shows that, when using our techniques, the disk throughput and the number of serviceable I/O requests are enhanced.

• Journal of the Korea Society of Computer and Information
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• v.29 no.1
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• pp.1-9
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• 2024

This paper proposes an integration of the ED-H scheduling algorithm, known for optimal real-time scheduling, with the LoRaEnergySim simulator. This integration facilitates the simulation of interactions between real-time scheduling algorithms for tasks with time constraints in Class-A LoRaWAN Class-A devices using a super-capacitor-based energy harvesting system. The time and energy characteristics of LoRaWAN status and state transitions are extracted in a log format, and the task model is structured to suit the time-slot-based ED-H scheduling algorithm. The algorithm is extended to perform tasks while satisfying time constraints based on CPU executions. To evaluate the proposed approach, the ED-H scheduling algorithm is executed on a set of tasks with varying time and energy characteristics and CPU occupancy rates ranging from 10% to 90%, under the same conditions as the LoRaEnergySim simulation results for packet transmission and reception. The experimental results confirmed the applicability of co-simulation by demonstrating that tasks are prioritized based on urgency without depleting the supercapacitor's energy to satisfy time constraints, depending on the scheduling algorithm.

• Journal of Korea Society of Industrial Information Systems
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• v.6 no.2
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• pp.38-46
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• 2001

This paper presents a new multiprocessor system and corresponding scheduling algorithm that can be applied for implementation of fine grain DSP algorithms such as digital filters. The newly proposed system uses one or more shared buses as the basic interconnection network between processors, and fixed amount of clock-skew is maintained between instruction execution of processors. This system not only can handle the interprocessor communications very efficiently but also can explicitly incorporate the interprocessor communication delay time into the multiprocessor scheduling model. This paper also presents a new scheduling strategy for implementing digital filters expressed in fully-specified flow graphs on the proposed system. The simulation result shows that well-known digital filters can be implemented on proposed multiprocessor in which the implementation satisfies the iteration period bound.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.149-158
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• 2019

The scheduling of planned maintenance problem of a system consisting of a number of components was studied. The purpose of maintenance scheduling is to minimize the cost of maintaining long-term operations. On the system side, the cost of a system shutdown can be minimized by grouping and inspecting a number of components. In addition, proper inspection cycles can be selected for each component to identify the failure sufficiently early to minimize the cost of the failure. To reduce the complexity of the calculations, the 'base interval approach' used in previous studies was applied and, in addition, the inspection cost savings from simultaneous inspections of multiple components were considered. To compare the effectiveness of inspection cost savings, this paper presents the results of simulation analysis performed by referring to the cases in the existing studies.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.764-769
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• 2000

A new transplant production system that produces high quality plug seedlings of specific crop has been studied. It is a plant factory designed to produce massive amount of virus free seedlings. The design concept for building this plant factory is to realize maximum energy efficiency and minimum initial investment and running cost. The basic production strategy is the sitespecific management. In this case, the management of the growth of individual plantlet is considered. This requires highly automated and information intensive production system in a closed aseptic environment the sterilized specific crops. One of the key components of this sophisticated system is the irrigation system. The conditions that this irrigation system has to satisfy are: 1. to perform the site specific crop management in irrigation and 2. to meet the no waste standard. The objective of this study is to develop an irrigation scheduling that can implement the no waste standard.