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Two Phase Heuristic Algorithm for Mean Delay constrained Capacitated Minimum Spanning Tree Problem (평균 지연 시간과 트래픽 용량이 제한되는 스패닝 트리 문제의 2단계 휴리스틱 알고리즘)

  • Lee, Yong-Jin
    • The KIPS Transactions:PartC
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    • v.10C no.3
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    • pp.367-376
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    • 2003
  • This study deals with the DCMST (Delay constrained Capacitated Minimum Spanning Tree) problem applied in the topological design of local networks or finding several communication paths from root node. While the traditional CMST problem has only the traffic capacity constraint served by a port of root node, the DCMST problem has the additional mean delay constraint of network. The DCMST problem consists of finding a set of spanning trees to link end-nodes to the root node satisfying the traffic requirements at end-nodes and the required mean delay of network. The objective function of problem is to minimize the total link cost. This paper presents two-phased heuristic algorithm, which consists of node exchange, and node shift algorithm based on the trade-off criterions, and mean delay algorithm. Actual computational experience and performance analysis show that the proposed algorithm can produce better solution than the existing algorithm for the CMST problem to consider the mean delay constraint in terms of cost.

Minimum Travel Time Paths for ATIS in Urban Road Networks Using Genetic Algorithms (유전자 알고리즘을 이용한 도시도로망에서의 첨단 여행자 정보시스템(ATIS) 운영계획)

  • 장인성;문형수
    • Journal of Korean Society of Transportation
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    • v.19 no.4
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    • pp.85-96
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    • 2001
  • This paper discusses the problem of finding the Origin-Destination(O-D) shortest path in urban road networks that have variable special qualifies such as time windows for passing as well as geometrical special qualities such as U-turn and left-turn prohibition. The focus of this paper is motivated by the problem of finding minimum travel time paths for an advanced traveler information system (ATIS) in the context of intelligent transportation system(ITS) application. The transportation network with variable and geometrical special qualities is a more realistic representation of the urban road network in the real word. But, the traditional and existing shortest path algorithms can not search practical shortest path that variable special quality is reflected. This paper presents a shortest path algorithm which can search reasonable shortest path information for the urban ATIS application within a real time. The algorithm is based on genetic algorithm(GA). The high performance of the proposed algorithm is demonstrated by computer simulations.

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A Receiver-driven TCP Flow Control for Memory Constrained Mobile Receiver (제한된 메모리의 모바일 수신자를 고려한 수신자 기반 TCP 흐름 제어)

  • 이종민;차호정
    • Journal of KIISE:Information Networking
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    • v.31 no.1
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    • pp.91-100
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    • 2004
  • This paper presents a receiver-driven TCP flow control mechanism, which is adaptive to the wireless condition, for memory constrained mobile receiver. A receiver-driven TCP flow control is, in general, achieved by adjusting the size of advertised window at the receiver. The proposed method constantly measures at the receiver both the available wireless bandwidth and the packet round-trip time. Depending on the measured values, the receiver adjusts appropriately the size of advertised window. Constrained by the adjusted window which reflects the current state of the wireless network, the sender achieves an improved TCP throughput as well as the reduced round-trip packet delay. Its implementation only affects the protocol stack at the receiver and hence neither the sender nor the router are required to be modified. The mechanism has been implemented in real environments. The experimental results show that in CDMA2000 1x networks the TCP throughput of the proposed method has improved about 5 times over the conventional method when the receiver's buffer size is limited to 2896 bytes. Also, with 64Kbytes of buffer site, the packet round-trip time of the proposed method has been reduced in half, compared the case with the conventional method.

A GA-Based Algorithm for Generating a Train Speed Profile Optimizing Energy Efficiency (에너지 최적의 열차 속도 궤적 생성을 위한 GA 기반 알고리즘)

  • Kang, Moon-Ho;Han, Moon-Seob
    • Journal of the Korean Society for Railway
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    • v.12 no.6
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    • pp.878-886
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    • 2009
  • This paper proposes an optimal algorithm for generating a train speed profile giving optimal energy efficiency based on GA (Genetic Algorithm) and shows its effectiveness with simulations. After simplifying the train operation mode to a maximum traction, a coasting and a maximum breaking, adjusting the coasting point to minimize the train consuming energy is the basic scheme. Satisfying the two constraints, running distance and running time between two stations, a coasting point is determined by GA with a fitness function consisting of a target running time. Simulation results have shown that multiple coasting points could exist satisfying both of the two constraints. After figuring out consumed energies according to the multiple coasting points, an optimal train speed profile with a coasting point giving the smallest consumed energy has been selected. Simulation blocks for the train performance simulation and GA have been designed with the Simulink.

Video Data Management based on Time Constraint Multiple Access Technique in Video Proxy Server (비디오 프록시 서버에서의 시간 제약 다중 요청 기법 기반 동영상 데이터 관리)

  • Lee, Jun-Pyo;Cho, Chul-Young;Kwon, Cheol-Hee;Lee, Jong-Soon;Kim, Tae-Yeong
    • Journal of the Korea Society of Computer and Information
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    • v.15 no.10
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    • pp.113-120
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    • 2010
  • Video proxy server which is located near clients can store the frequently requested video data in storage space in order to minimize initial latency and network traffic significantly. However, due to the limited storage space in video proxy server, an appropriate video selection method is needed to store the videos which are frequently requested by users. Thus, we present a time constraint multiple access technique to efficiently store the video in video proxy server. If the video is requested by user, it is temporarily stored during the predefined interval and then, delivered to the user. A video which is stored is deleted or moved into the storage space of video proxy server depending on the request condition. In addition, we propose a video deletion method in video proxy server for newly stored video data. The simulation results show that the proposed method performs better than other methods in terms of the block hit rate and the number of block deletion.

Efficient Analysis of Shear Walls with Openings (개구부가 있는 전단벽의 효율적인 해석)

  • 김현수;남궁계홍;이동근
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.2
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    • pp.237-249
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    • 2002
  • The wall system that is composed only of reinforced concrete walls and slabs is adopted on many high-rise apartment buildings recently constructed. In the apartment buildings, a shear wall may have one or mote openings for functional reasons. Many researches on the analysis of shear wall with openings were performed. But, some restrictions prevent those research results being applied to practical analysis and design procedure. It is necessary to use subdivided finite elements lot accurate analysis of the wall system with openings. But it would cost tremendous amount of analysis time and computer memory if the entire building structure is subdivided into a finer mesh. An efficient analysis method which can be used regardless of the number, size and location of openings is proposed in this study. The analysis method uses super element, matrix condensation technique and fictitious beam technique. Analyses of example structures having various types of openings were performed to verify the efficiency of proposed method. It was confirmed that the proposed method have outstanding accuracy with drastically reduced time and computer memory from the analyses of example structures.

LoRa Network based Parking Dispatching System : Queuing Theory and Q-learning Approach (LoRa 망 기반의 주차 지명 시스템 : 큐잉 이론과 큐러닝 접근)

  • Cho, Youngho;Seo, Yeong Geon;Jeong, Dae-Yul
    • Journal of Digital Contents Society
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    • v.18 no.7
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    • pp.1443-1450
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    • 2017
  • The purpose of this study is to develop an intelligent parking dispatching system based on LoRa network technology. During the local festival, many tourists come into the festival site simultaneously after sunset. To handle the traffic jam and parking dispatching, many traffic management staffs are engaged in the main road to guide the cars to available parking lots. Nevertheless, the traffic problems are more serious at the peak time of festival. Such parking dispatching problems are complex and real-time traffic information dependent. We used Queuing theory to predict inbound traffics and to measure parking service performance. Q-learning algorithm is used to find fastest routes and dispatch the vehicles efficiently to the available parking lots.

Preparation and Characterizations of Various Chitosan from Chitin (Chitin으로부터 다양한 chitosan의 제조와 특성)

  • 조형재;황성규;이기창;이한섭;김판기
    • Journal of Food Hygiene and Safety
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    • v.13 no.1
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    • pp.34-40
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    • 1998
  • Chitin is known as biodegradable natural polymer. But, in spite of various application of chitin from waste marine sources, commercial use of chitin has been limited due to highly resistance to chemicals and the absense of proper solvents. Therefore, we studied that another viscosity chitosan were prepared from chitin which were deacetylated under various concentration of NaOH solution, reaction time and temperature by the application of Mirna's method. The major parameters for these manufacturing methods were found to be concentration of alkali solution, reaction time and temperature etc. Besides, we studied that various chitosan derivatives were prepared from chitin by crosslinkage with epichlorohydrin and 1,3-dichloropropanol. The effects of these parameters on another viscosity(molecular weight) chitosan and crosslinked chitosan dervatives were investigated by various analysis apparatus. SEM analysis showed that both chitin and chitosan had a particle shaped morphology and another molecular weight chitosan according to the particle size was much smaller than that of chitin.

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Algorithms for Detecting Coupling Faults in Semiconductor RAM's (반도체 RAM의 결합고장을 검출하는 알고리듬)

  • 여정모;조상복
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.30A no.1
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    • pp.51-63
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    • 1993
  • "Algorithm DA" is proposed to test linked 2-CFs(2-Coupling Faults) with order 2 or 3 which are not perfectly detected in conventional algorithms. "Test 1*", "Test 2*" and "Algorithm RA" are proposed restricted 3-CFS. The time complexity of "Test 1*" is reduced in view of the detection of 3-CFS. "Test 2*" and "Algorithm RA" have not only the reduces time complexity but also the improved fault coverage in comparison with conventional algorithms. And "Algorithm RA" can be applied step by step according to the degree of the fault coverage. If "Algorithm RA" is applied to the memory with parallel test. its time complexity is reduced considerably. It is proved that the MT(March Test) with nonlinear address sequences can not detect perfectly the CFs more complex than linked 2-CFs with order 3.ss sequences can not detect perfectly the CFs more complex than linked 2-CFs with order 3.

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Energy-Efficient Real-Time Task Scheduling for Battery-Powered Wireless Sensor Nodes (배터리 작동식의 무선 센서 노드를 위한 에너지 효율적인 실시간 태스크 스케줄링)

  • Kim, Dong-Joo;Kim, Tae-Hoon;Tak, Sung-Woo
    • Journal of Korea Multimedia Society
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    • v.13 no.10
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    • pp.1423-1435
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    • 2010
  • Building wireless sensor networks requires a constituting sensor node to consider the following limited hardware resources: a small battery lifetime limiting available power supply for the sensor node, a low-power microprocessor with a low-performance computing capability, and scarce memory resources. Despite such limited hardware resources of the sensor node, the sensor node platform needs to activate real-time sensing, guarantee the real-time processing of sensing data, and exchange data between individual sensor nodes concurrently. Therefore, in this paper, we propose an energy-efficient real-time task scheduling technique for battery-powered wireless sensor nodes. The proposed energy-efficient task scheduling technique controls the microprocessor's operating frequency and reduces the power consumption of a task by exploiting the slack time of the task when the actual execution time of the task can be less than its worst case execution time. The outcomes from experiments showed that the proposed scheduling technique yielded efficient performance in terms of guaranteeing the completion of real-time tasks within their deadlines and aiming to provide low power consumption.