• Title/Summary/Keyword: optimization problem

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Optimal Positioning of the Base Stations in PS-LTE Systems (PS-LTE 환경에서 최적기지국 위치 선정)

  • Kim, Hyun-Woo;Lee, Sang-Hoon;Yoon, Hyun-Goo;Choi, Yong-Hoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.4
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    • pp.467-478
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    • 2016
  • In this paper, we try to find the optimal locations of NeNB(Nomadic evolved NodeB)s for maximizing the overall throughput of the PS-LTE networks. Since finding optimal locations of all NeNBs in a given area is NP-hard(Non-deterministic Polynomial time-hard) problem, we proposed a PSO-based heuristic approach. In order to evaluate the performance, we conducted two experiments. We compared performance with other schemes such as Exhaustive Search, Random Walk Search, and locating neighboring NeNBs with the same NeNB-to-NeNB distance. The proposed method showed the similar results to the exhaustive search method in terms of locating optimal position and user's data throughput. The proposed method, however, has the fast and consistent convergence time.

Capacity Optimization of a 802.16e OFDMA/TDD Cellular System using the Joint Allocation Algorithm of Sub-channel and Transmit Power Part I : Sub-channel Allocation Algorithm for Throughput Maximization in the Downlink insuring Fairness and Power Allocation Algorithm for efficient use of Extra Transmit Power efficiently (802.16e OFDMA/TDD 셀룰러 시스템의 성능 최적화를 위한 부채널과 전송전력 결합 할당 알고리즘 Part I : 하향링크에서 공평성이 보장되는 수율 최대화 부채널 할당 알고리즘 및 잉여 전송전력의 효율적인 사용을 위한 전력할당 알고리즘)

  • Ko, Sang-Jun;Chang, Kyung-Hi;Kim, Jae-Hyeong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.3A
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    • pp.247-260
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    • 2007
  • This paper solves the problem of finding a suitable sub-channel and power joint allocation method for multiple users in 802.16e OFDMA/TDD cellular systems. The joint allocation is thatfirstly the sub-channel is allocated to the users and then suitable power is allocated. We propose a FASA (Fairness insured Aggressive Sub-channel Allocation) algorithm which is a dynamic channel allocation algorithm considering all users' channel state information conditionally to maximize fairness and throughput. The improved CHC algorithm, which is dynamic power allocation algorithm, is also proposed in this paper The Improved CHC algorithm collects the extra of the downlink transmit power and then re-allocates it to other users. Simulation results show that the proposed improved CHC algorithm additionally increases the fairness and sector throughput.

Analysis of Programming Techniques for Creating Optimized CUDA Software (최적화된 CUDA 소프트웨어 제작을 위한 프로그래밍 기법 분석)

  • Kim, Sung-Soo;Kim, Dong-Heon;Woo, Sang-Kyu;Ihm, In-Sung
    • Journal of KIISE:Computing Practices and Letters
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    • v.16 no.7
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    • pp.775-787
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    • 2010
  • Unlike general-purpose CPUs, the GPUs have been specialized as many-core streaming processors, and are frequently replacing the CPUs in an increasing range of computations thanks to their outstanding parallel computing capacity. In order to respond to such trend, NVIDIA has recently issued a new parallel computing architecture called CUDA(Compute Unified Device Architecture), offering a flexible GPU programming environment for GPGPU(General Purpose GPU) computing. In general, when programmers use the CUDA API, they should clearly understand many aspects of GPU's computing architecture to produce efficient parallel software. In this article, we explain several optimization techniques for CUDA programming that we have verified through a lot of experiment and trial and error, and review how those techniques affect the performance of code execution. In particular, we use a specific problem as an example to analyze several elements that affect performances, such as effective accesses to hierarchical memory system, processor occupancy, and latency hiding. In conclusion, we present several directions that may be utilized effectively in CUDA-based parallel programming.

A Study of Flexible Protein Structure Alignment Using Three Dimensional Local Similarities (단백질 3차원 구조의 지역적 유사성을 이용한 Flexible 단백질 구조 정렬에 관한 연구)

  • Park, Chan-Yong;Hwang, Chi-Jung
    • The KIPS Transactions:PartB
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    • v.16B no.5
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    • pp.359-366
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    • 2009
  • Analysis of 3-dimensional (3D) protein structure plays an important role of structural bioinformatics. The protein structure alignment is the main subjects of the structural bioinformatics and the most fundamental problem. Protein Structures are flexible and undergo structural changes as part of their function, and most existing protein structure comparison methods treat them as rigid bodies, which may lead to incorrect alignment. We present a new method that carries out the flexible structure alignment by means of finding SSPs(Similar Substructure Pairs) and flexible points of the protein. In order to find SSPs, we encode the coordinates of atoms in the backbone of protein into RDA(Relative Direction Angle) using local similarity of protein structure. We connect the SSPs with Floyd-Warshall algorithm and make compatible SSPs. We compare the two compatible SSPs and find optimal flexible point in the protein. On our well defined performance experiment, 68 benchmark data set is used and our method is better than three widely used methods (DALI, CE, FATCAT) in terms of alignment accuracy.

Optimum Design of Composite Framed Structures Based Reliability Index (신뢰성지수를 고려한 합성 뼈대구조물의 최적설계에 관한 연구)

  • Jung, Young Chae;Kim, Jong Gil
    • Journal of Korean Society of Steel Construction
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    • v.15 no.4 s.65
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    • pp.389-401
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    • 2003
  • The purpose of this study is to develop an algorithm, which can be designed the optimal sections of the composite framed structures constituted with the beams and the columns consisted of H type of steel section and concrete considering the reliability index. The optimized problem or the composite framed structures is formulated with the objective function and the constraints taking the section sizes as the design variables. The objective functions are constituted by the total costs of constructions. Also, the constraints are derived by considering the reliability index of section stress and allowable stress. The algorithm optimized the section of the composite framed structures utilizes the SUMT method using the modified Newton-Raphson direction method. The optimizing algorithm developed in this study is applied to the numerical examples with respecting a one-bay, one-story composite framed structure and a one-bay five-story one for the practical utilization of design on the composite framed structures using the reliability indices$({\beta})$ three and zero. In addition, their numerical results are compared and analyzed to examine the possibility of optimization the applicability, and the convergence this algorithm.

A Methodology of Databased Energy Demand Prediction Using Artificial Neural Networks for a Urban Community (인공신경망을 이용한 데이터베이스 기반의 광역단지 에너지 수요예측 기법 개발)

  • Kong, Dong-Seok;Kwak, Young-Hun;Lee, Byung-Jeong;Huh, Jung-Ho
    • 한국태양에너지학회:학술대회논문집
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    • 2009.04a
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    • pp.184-189
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    • 2009
  • In order to improve the operation of energy systems, it is necessary for the urban communities to have reliable optimization routines, both computerized and manual, implemented in their organizations. However, before a production plan for the energy system units can be constructed, a prediction of the energy systems first needs to be determined. So, several methodologies have been proposed for energy demand prediction, but due to uncertainties in urban community, many of them will fail in practice. The main topic of this paper has been the development of a method for energy demand prediction at urban community. Energy demand prediction is important input parameters to plan for the energy planing. This paper presents a energy demand prediction method which estimates heat and electricity for various building categories. The method has been based on artificial neural networks(ANN). The advantage of ANN with respect to the other method is their ability of modeling a multivariable problem given by the complex relationships between the variables. Also, the ANN can extract the relationships among these variables by means of learning with training data. In this paper, the ANN have been applied in oder to correlate weather conditions, calendar data, schedules, etc. Space heating, cooling, hot water and HVAC electricity can be predicted using this method. This method can produce 10% of errors hourly load profile from individual building to urban community.

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Development of Relocation Method for Construction Materials using FP-Growth (FP-Growth 기법을 활용한 건자재 재고 재배치 기법 개발)

  • Lee, Hyo-Jun;Kim, Jae-Won;Shin, Kwang Sup
    • The Journal of Bigdata
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    • v.2 no.1
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    • pp.49-58
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    • 2017
  • The inventory location is the mos important factor which decide the efficiency of picking orders. According to the inventory location, it is possible to optimize the route for picking order, and then it makes us to expect the cost reduction and efficiency improvement. However, it is practical situation to make decisions where to keep the products based on manager's intuition and experience, not based on the systematical or analytical approach. In this research, with the practical order data of cropper product and layout for the storage yard, the association rules have found, and then the new methodology has been devised to make the decision where to keep the inventory. By utilizing the practical order data for a year, it has been proved that the proposed approach can reduce the total distance of the all routes for picking order and solve the problem of delayed delivery.

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An Evolutionary Algorithm to the Threshold Detection Method for the M-ary Holographic Data Storage (M-ary 홀로그래픽 저장 장치의 적응적 문턱값 검출을 위한 진화 연산 기법)

  • Kim, Sunho;Lee, Jieun;Im, Sungbin
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.5
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    • pp.51-57
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    • 2014
  • In this paper, we introduce the adaptive threshold detection scheme based on an evolutionary arithmetic algorithm for the M-ary holographic data storage(HDS) system. The genetic algorithm is a particular class of evolutionary arithmetic based on the process of biological evolution, which is a very promising technique for optimization problem and estimation applications. In this study, to improve the detection performance that is degraded by the HDS channel environment and the pixel misalignment, the threshold value was assumed to be a population set of the evolutionary algorithm. The proposed method can find an appropriate population set of bit threshold, which minimizes bit error rate(BER) as increased generation. For performance evaluation, we consider severe misalignment effect in the 4-ary holographic data storage system. Furthermore, we measure the BER performance and compare the proposed methods with the conventional threshold detection scheme, which verifies the superiority of the proposed scheme.

A Latency Optimization Mapping Algorithm for Hybrid Optical Network-on-Chip (하이브리드 광학 네트워크-온-칩에서 지연 시간 최적화를 위한 매핑 알고리즘)

  • Lee, Jae Hun;Li, Chang Lin;Han, Tae Hee
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.7
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    • pp.131-139
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    • 2013
  • To overcome the limitations in performance and power consumption of traditional electrical interconnection based network-on-chips (NoCs), a hybrid optical network-on-chip (HONoC) architecture using optical interconnects is emerging. However, the HONoC architecture should use circuit-switching scheme owing to the overhead by optical devices, which worsens the latency unfairness problem caused by frequent path collisions. This resultingly exert a bad influence in overall performance of the system. In this paper, we propose a new task mapping algorithm for optimizing latency by reducing path collisions. The proposed algorithm allocates a task to a certain processing element (PE) for the purpose of minimizing path collisions and worst case latencies. Compared to the random mapping technique and the bandwidth-constrained mapping technique, simulation results show the reduction in latency by 43% and 61% in average for each $4{\times}4$ and $8{\times}8$ mesh topology, respectively.

Energy Efficiency of Decoupled RF Energy Harvesting Networks in Various User Distribution Environments (다양한 사용자 분포 환경에서의 비결합 무선 에너지 하베스팅 네트워크의 에너지 효율)

  • Hwang, Yu Min;Sun, Young Ghyu;Shin, Yoan;Kim, Dong In;Kim, Jin Young
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.17 no.4
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    • pp.159-167
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    • 2018
  • In this paper, we propose an algorithm to optimize energy efficiency in a multi-user decoupled RF energy harvesting network and experiment on the trend of energy efficiency change assuming users' various geographical distribution scenarios. In the RF energy harvesting network where both wireless data transmission and RF energy harvesting are simultaneously performed, the energy efficiency is a key indicator of network performance, and it is necessary to investigate how various factors can affect the energy efficiency. In order to increase energy efficiency effectively, we can confirm that users' distributions are important factors in the RF energy harvesting network from the simulation results.