• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.256-258
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• 2005

분자모델링 시뮬레이션 도구는 신 물질과 신약개발을 위한 가상 실험을 하는데 사용되는 중요한 도구이다. 이 도구는 분자 물질간의 결합을 통하여 에너지 계산을 하여 가장 낮은 에너지 준위를 보여주는 위치를 탐색한다. 에너지 결과를 빠르게 제공하면 사용자가 분자 물질을 결합하여 안정된 위치를 찾는데 많은 도움을 줄 수 있다. 본 연구에서는 에너지 계산을 고성능으로 처리 할 수 있는 분산처리시스템과 실시간 응답성 보장 스케줄링 알고리즘을 적용한 환경에 사용자 입력 예측 시스템을 추가하여 에너지 계산을 기존 시스템 보다. 빠르게 요청하였으며, 에너지 계산 결과의 응답성을 향상 시켰다. 또한 사용자 입력 예측시스템에서 발생하는 오차의 문제를 예측 시스템의 운영 방식을 통해 해결 방법을 제시하고 있다. 본 연구는 에너지 결과의 응답성 보장을 통하여 사용자가 좀 더 빠르게 안정된 결합 위치를 찾도록 도와준다.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11b
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• pp.1631-1634
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• 2002

멀티미디어 서버는 클라이언트가 요청한 멀티미디어 데이터 스트림을 효율적으로 제공하기 위해 사용된다. 현재, 정보통신 기술의 발달로 인해 멀티미디어 서버는 멀티미디어 정보를 온라인으로 서비스 할 수 있게 되었다. 하지만 네트워크 상에서 발생하는 Packet Delay 에 때문에 서버에서 사용자에게 연속적이고 엄격한 실시간 제약이 있는 비디오 전송과 같은 멀티미디어 서비스를 제공하는 것은 매우 힘들다. 따라서, 본 논문에서는 서버에서 필요한 Packet 를 먼저 전송하여 Packet Delay 를 줄이는 방법을 제안하였다. MPEG-4 에서 오브젝트의 AU(Access Unit)들의 디코딩 시간을 표시하는 DTS(Decoding Time Stamp)를 참조하여 생성된 Deadline threshold 를 기준으로 Deadline 이 가장 빠른 AU부터 전송하는 스케줄링 알고리즘을 이용하여 MPEC-4 미디어 오브젝트를 스트리밍한다.

• Journal of Digital Contents Society
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• v.2 no.2
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• pp.167-178
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• 2001

For high performance Grid environments, an effective GIS(Grid Information System) should be adopted. In the design of GIS architecture, its grid resource information model provides a key basis. This paper presents our study on the exploration of a high performance grid resource information model. According the exploration, we identified the followings. The resource information model should clearly address the issues of relation descriptions as well as resource descriptions, issues related to scheduling support, the issue of decoupling the expression model of resource information from data repository models, and finally the issue of decoupling user-level resource descriptions from system-level resource descriptions. Based on the proposed conceptual organization of resource information models, analysis result for the existing resource information models are presented.

• Journal of the Korea Computer Industry Society
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• v.3 no.5
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• pp.529-546
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• 2002

A VOD server, which is the central component for constructing VOD systems, requires to provide high bandwidth and continuous real-time delivery. It is also necessary to the sophisticated disk scheduling and data placement schemes in VOD sewers. One of the most common problem facing in such a system is the high initial latency time to service multiple users concurrently. In this paper, we propose a dynamic stream merging scheme for reducing the initial latency time in VOD servers. The proposed scheme allows clients to merge streams on a request as long as their requests fall within the reasonable time interval. The basic idea behind the dynamic stream merging is to merge multiple streams into one by increasing the frame rate of each stream. In the performance study, the proposed scheme can reduce the initial latency time under the minimum buffer use and also can enhance the performance of the VOD server with respect to the capacity of user admission.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6B
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• pp.495-507
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• 2006

In wireless local area networks (WLANs), the successful design of scheduling algorithm is a key factor in guaranteeing the various quality of service (QoS) requirements for the stringent real-time constraints of multimedia services. In this paper we propose a multipolling-based dynamic scheduling algorithm for providing delay guarantees to multimedia traffics such as MPEG streams. The dynamic algorithm exploits the characteristics of MPEG stream, and uses mini frames for feedback control in order to deliver dynamic parameters for channel requests from stations to the point coordinator (PC) operating at the access point (AP). In this scheme, the duration of channel time allocated to a station during a superframe is changed dynamically depending on the MPEG frame type, traffic load and delay bound of the frame, etc. Performance of the proposed scheme is investigated by simulation. Our results show that compared to conventional scheme, the proposed scheme is very effective and has high performance while guaranteeing the delay bound.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.165-175
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• 2016

A data allocation technique is essential to improve the performance of data broadcast systems. This paper explores the issues for allocating data items on broadcast channels to process multiple-data queries in the environment where query profiles and query request rates are given, and proposes a new data allocation scheme named QBDA. The proposed scheme allows the query with higher request rate to have higher priority to schedule its data items and introduces the concept of marking to reduce data conflicts. Simulation is performed to evaluate the performance of QBDA. The simulation results show that the proposed scheme outperforms other schemes in terms of the average response time since it can process queries with high request rate fast and show a very desirable characteristics in the aspects of query data adjacency and data conflict probability.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.6
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• pp.584-590
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• 2016

This paper proposed "Priority Scheduling and MultiPath Routing Protocol (RRPS) for preventing communication disruption in the urban environment" to minimize the disconnection or disruption of V2I and V2V communication in the urban environment where communication is frequently disconnected according to density. The flow of the RRPS is explained as follows. RSU Request Priority Scheduling (RRPS) is used to apply the priority of the request message prior to reaching the end line by using the Start Line and End Line, which are the management areas of the RSU). This paper also proposed MPRP (Multi Path Routing Protocol) design to set up the multipath to the destination. As a result, the proposed RRPS improves the processing efficiency of V2I by applying priority scheduling to the message of the vehicle requesting the information in the RSU, and can prevent the communication disconnection. Thereby, it is improved the transmission success probability.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.11
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• pp.379-384
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• 2016

NAND flash storage is widely used for computer systems, because of it has faster response time, lower power consumption, and larger capacity per unit area than hard disk. However, currently used I/O scheduler in the operating system is optimized for characteristics of the hard disk. Therefore, the conventional I/O scheduler includes the unnecessary overhead in the case of the NAND flash storage to be applied. Particularly, when the write requests performed intensively, garbage collection is performed intensively. So, it occurs the problem that the processing of the I/O request delay. In this paper, we propose the new I/O scheduler to solve the problem of garbage collection performs intensively, and to optimize for NAND flash storage. In the result of performance evaluation, proposed scheme shows an improvement the user responsiveness by reducing 1% of the average read response time and 78% of the maximum response time.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.7
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• pp.48-56
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• 2011

Recently, new storage device SSD(Solid State Disk) based on NAND flash memory is gradually replacing HDD(Hard Disk Drive) in mobile device and thus a variety of research efforts are going on to find the cost-effective ways of performance improvement. By increasing the NAND flash channels in order to enhance the bandwidth through parallel processing, DRAM buffer which acts as a buffer cache between host(PC) and NAND flash has become the bottleneck point. To resolve this problem, this paper proposes an efficient low-cost scheme to increase SSD performance by improving DRAM buffer bandwidth through scheduling techniques which utilize DRAM multi-banks. When both host and NAND flash multi-channels request access to DRAM buffer concurrently, the proposed technique checks their destination and then schedules appropriately considering properties of DRAMs. It can reduce overheads of bank active time and row latency significantly and thus optimizes DRAM buffer bandwidth utilization. The result reveals that the proposed technique improves the SSD performance by 47.4% in read and 47.7% in write operation respectively compared to conventional methods with negligible changes and increases in the hardware.

• The KIPS Transactions:PartA
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• v.11A no.5
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• pp.355-364
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• 2004

These days, various clustering technologies have been adopted to construct web sites. High performance hardware switches have good performance, but have disadvantage of high cost for constructing small and middle-sized web sites. Now a days, many sites have been constructed with the LVS (Linux Virtual Server), which is free of charge and has good performance. Having a centralized load balancing with one front-end, the LVS causes a bottleneck when it receives all at once. In the paper, we suggest a way to remove the LVS bottleneck by providing multiple front-ends. In this architecture, all of cluster nodes act as both a front-end and a back-end. When the load of a node receiving requests is not large enough, the node responds to the client directly. When the load of a node is large enough, the node send the request to a node which is selected by a scheduling algorithm. The scheduling algorithm is discussed to balance loads between servers. While single front-end cluster raises the throughput curvedly, the multiple front-end cluster raises the throughput linearly.