• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.10B
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• pp.1867-1875
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• 1999

This paper presents a very unique and analytic method for scheduling messages routed through a non-blocking switch. The laxities of schedulable messages are decomposed and the laxity table is rearranged so that the packets to be scheduled in the next time instance are placed in the diagonal of the traffic matrix. And the modified MLF-SDR algorithm is performed on the table. We present some examples and simulation results which show that the success rate is very high, even when the size of which is large.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11b
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• pp.865-868
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• 2003

ESP는 Effective System Performance의 약자로 NERSC에서 개발한 HPC 시스템에 대한 새로운 성능 측정 기준이다. 기존 HPC 시스템에서는 주로 성능 측정의 대상으로 시스템[프로세서]의 계산 성능에 주안점을 두었지만 시스템의 효율성은 무시되는 경향이 있었다. ESP는 실제 운영환경에서 배치 작업 스케줄러 및 병렬 작업 환경에 영향을 받는 시스템 효율성(ESP:Effective System Performance)을 측정하는 데 주안점을 두고 있다. KISTI 슈퍼컴퓨팅센터는 2003년 7월 국내 최고 성능의 슈퍼컴퓨터인 IBM p690+ 시스템의 도입을 완료하고 ESP를 사용하여 배치 작업 스케줄러인 LoadLeveler의 스케줄링 알고리즘에 따른 시스템 효율성 벤치마크를 수행하였다. 이 벤치마크를 통해서 효율적인 시스템 자원 활용을 위한 작업 스케줄링 알고리즘의 적용 근거를 마련하게 되었다.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2002.05a
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• pp.106-111
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• 2002

해상운송에서 규모의 경제 이익을 달성하기 위해 선박의 크기가 대형화되고, 항만이 중심항만과 주변항만으로 양분화 되어감에 따라 컨테이너 터미널의 효율적 운영을 통한 경쟁력 확보가 중요시되고 있다. 컨테이너의 효율적인 적하는 선박의 효율과 양적하에 직접 관여하는 터미널 중심 장비인 켄트리 크레인의 효율을 극대화하도록 계획되어야 한다. 적하 문제는 선박의 크기와 각 터미널에서의 적하량에 종속되는 NP-hard 문제이다 본 연구에서는 컨테이너 적하 문제를 크게 두 개의 단계로 나누어 적하 계획을 수행한다. 무한한 경우의 수를 두 단계로 나눈 계획 시스템에 의해 크기를 줄인다. 첫 번째 단계는 컨테이너를 선박의 각 해치별로 배치하는 단계이고, 두 번째 단계는 각 해치별로 배정된 컨테이너를 특정 슬롯에 배치하는 것이다. 이렇게 분해된 문제의 각 단계에서 유전 알고리즘(Genetic Algorithm)을 사용하여 최적의 적하계획을 세운다. 그리고 정기 컨테이너선의 운항모형을 수립하고, 각 항구에서의 양·적하를 수행하여 구축된 시스템의 적합성을 시뮬레이션하여 평가한다

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.4
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• pp.447-459
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• 2013

Many problems need to be solved before vision systems can actually be applied in industry, such as the precision of the kinematics model of the robot control algorithm based on visual information, active compensation of the camera's focal length and orientation during the movement of the robot, and understanding the mapping of the physical 3-D space into 2-D camera coordinates. An algorithm is proposed to enable robot to move actively even if the relative positions between the camera and the robot is unknown. To solve the correction problem, this study proposes vision system model with six camera parameters. To develop the robot vision control algorithm, the N-R and EKF methods are applied to the vision system model. Finally, the position accuracy and processing time of the two algorithms developed based based on the EKF and the N-R methods are compared experimentally by making the robot perform slender bar placement task.

• Journal of the Korea Society of Computer and Information
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• v.19 no.8
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• pp.63-71
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• 2014

This paper proposes an algorithm that forms the clusters on the basis of hop distance in order to improve the actor coverage and connectivity in the sink-based wireless sensor and actor networks. The proposed algorithm forms the clusters that are distributed evenly in the target area by electing the CHs(Cluster Heads) at regular hop intervals from a sink. The CHs are elected sequentially from the sink in order to ensure the connectivity between the sink and the actors that are located on the CHs. Additionally, the electing are achieved from the area of the higher rate of the sensors density in order to improve the actor coverage. The number of clusters that are created in the target area and the number of the actors that are placed on the positions of the CHs are reduced by forming the clusters with regular distribution and minimizing the overlap of them through the proposed algorithm. Simulations are performed to verify that the proposed algorithm constructs the actor network that is connected to the sink. Moreover, we shows that the proposed algorithm improves the actor coverage and, therefore, reduces the amount of the actors that will be deployed in the region by 9~20% compared to the IDSC algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.7B
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• pp.595-605
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• 2012

DV-Hop is one of the well known range-free localization algorithms. The algorithm works well in case of isotropic network since the sensor and anchor nodes are placed in the entire area. However, it results in large errors in case of anisotropic networks where the hop count between nodes is not linearly proportional to the Euclidean distance between them. Hence, we proposed a novel range-free algorithm for anisotropic networks to improve the localization accuracy. In the paper, the Euclidean distance between anchor node and unknown node is estimated by the average hop distance calculated at each hop count with hop count and distance information between anchor nodes. By estimating the unknown location of nodes with the estimated distance estimated by the average hop distance calculated at each hop, the localization accuracy is improved. Simulation results show that the proposed algorithm has more accuracy than DV-Hop.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.1
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• pp.162-169
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• 2022

In a dynamically changing time-varying network environment, the optimal moving pattern of edge devices can be applied to distributing computing resources to edge cloud servers or deploying new edge servers in the FEC(Fog/Edge Computing) environment. In addition, this can be used to build an environment capable of efficient computation offloading to alleviate latency problems, which are disadvantages of cloud computing. This paper proposes an algorithm to extract the optimal moving pattern by analyzing the moving path of multiple edge devices requiring application services in an arbitrary spatio-temporal environment based on frequency. A comparative experiment with A^* and Dijkstra algorithms shows that the proposed algorithm uses a relatively fast execution time and less memory, and extracts a more accurate optimal path. Furthermore, it was deduced from the comparison result with the A^* algorithm that applying weights (preference, congestion, etc.) simultaneously with frequency can increase path extraction accuracy.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.587-590
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• 2011

고정형 센서노드들로 구성된 기존의 무선 센서 네트워크는 다양한 응용분야에서 사용되고 있다. 하지만, 센서노드에 이동기능이 추가되면 적절한 움직임을 통해 센싱 영역을 최대화 할 수 있다. 이러한 측면에서 최근 센서의 자율배치에 관련한 연구가 활발하게 진행 중이다. 기존 연구에서의 센서 이동은 대부분 2차원에서의 자율배치에 관하여 연구가 되어 왔다. 본 논문에서는 2차원에서의 자율배치가 아닌 3차원 공간에서의 센서노드의 자율배치에 대한 알고리즘과 이의 결과를 제시한다.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.1_2
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• pp.95-101
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• 2004

The scheduling problem that maps independent tasks to heterogeneous resources in distributed computing systems is known as NP-complete［1］. GRID［2］ is an example of distributed systems that consisted of heterogeneous resources. Many algorithms to solve this problem have been presented［1,3,4,5］. The scheduling algorithm can be classified into static scheduling algorithms and dynmic scheduling algorithms. A dynamic scheduling algorithm can be used when we can not predict the priority of tasks. Moreover, a dynamic scheduling algorithm can be divided into on-line mode algorithm and batch mode algorithm according to the scheduling time［1,6］. In this paper, we propose a new on-line mode scheduling algorithm. By extensive simulation, we can see that our scheduling algorithm outperforms previous scheduling algorithms.

• Journal of Advanced Navigation Technology
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• v.20 no.3
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• pp.218-225
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• 2016

Null steering and beam steering are known well as anti-jamming methods in GPS anti-jamming system. Null steering gets a noise attenuation effect for the direction of jamming and beam steering earns additional gain synthesis for the direction of satellite signals. According to the research in the article for signal processing, it expresses that the N array antenna is effective for N-1 number of jamming signal by math public interest, however, the two algorithms analysis is not unknown for the operating condition of the realistic vehicle. In this paper, we modeled anti-jamming system using 4 and 7 array antenna and showed the two algorithms performance (PM, LCMV) when considering the number of antenna array, jammers and vehicle position (horizontal, vertical). In result, we showed that the case of vertical position of the vehicle which has large tilt angle for the relative position of satellites and jammers, has about 10 dB gain more in comparison with one of vertical position in spite of same JSR condition.