• Title/Summary/Keyword: Local Minimum

Search Result 825, Processing Time 0.022 seconds

A Local Representative Method for Maintaining a Stable Transmission Rate in Multicasting (멀티캐스트 환경에서의 안정적 전송률 유지를 위한 지역대표자 기법)

  • Jang Jong-Woo;Koo Myung-Mo;Kim Sang-Bok
    • Journal of Korea Multimedia Society
    • /
    • v.8 no.9
    • /
    • pp.1208-1215
    • /
    • 2005
  • In the case of receiving feedbacks from many receivers in the multimedia application using multicasting, the traffic congestion caused bp heavy traffic results in the problem of transmission rate decrease. In solving of this, the local representative method is adopted. However, the control of transmission rate in consideration of all receivers caused uncongested local transmission rate to get slower. In this paper, there is a local representative in solving of this problem. When the transmission rate of a group is less than minimum support threshold, the local representative recounts the transmission rate without congested receivers. Therefore, The local representative method has improved the problem that the transmission rate of uncongested local decreases. The result of this paper shows that this method provides stable transmission rate rather than those of existing methods.

  • PDF

GOODNESS-OF-FIT TEST USING LOCAL MAXIMUM LIKELIHOOD POLYNOMIAL ESTIMATOR FOR SPARSE MULTINOMIAL DATA

  • Baek, Jang-Sun
    • Journal of the Korean Statistical Society
    • /
    • v.33 no.3
    • /
    • pp.313-321
    • /
    • 2004
  • We consider the problem of testing cell probabilities in sparse multinomial data. Aerts et al. (2000) presented T=${{\Sigma}_{i=1}}^{k}{[{p_i}^{*}-E{(p_{i}}^{*})]^2$ as a test statistic with the local least square polynomial estimator ${{p}_{i}}^{*}$, and derived its asymptotic distribution. The local least square estimator may produce negative estimates for cell probabilities. The local maximum likelihood polynomial estimator ${{\hat{p}}_{i}}$, however, guarantees positive estimates for cell probabilities and has the same asymptotic performance as the local least square estimator (Baek and Park, 2003). When there are cell probabilities with relatively much different sizes, the same contribution of the difference between the estimator and the hypothetical probability at each cell in their test statistic would not be proper to measure the total goodness-of-fit. We consider a Pearson type of goodness-of-fit test statistic, $T_1={{\Sigma}_{i=1}}^{k}{[{p_i}^{*}-E{(p_{i}}^{*})]^2/p_{i}$ instead, and show it follows an asymptotic normal distribution. Also we investigate the asymptotic normality of $T_2={{\Sigma}_{i=1}}^{k}{[{p_i}^{*}-E{(p_{i}}^{*})]^2/p_{i}$ where the minimum expected cell frequency is very small.

A New Algorithm Based on ASH in Local Modes Detection of Pathrate (ASH를 이용한 Pathrate에서의 Local Mode 검출 알고리즘)

  • Huang, Yue;Kim, Yong-Soo
    • Journal of the Korea Society of Computer and Information
    • /
    • v.11 no.5 s.43
    • /
    • pp.1-8
    • /
    • 2006
  • Network measurement is a vital part of network traffic engineering. In a network, the metric 'capacity' characterizes the maximum throughput the path can provide when there is no traffic load, or the minimum transmission rate among all links in a path. Pathrate is one of the most widely used network capacity measurement tools nowadays. It's famous for its accurate estimation result and non restriction of the temporal network traffic condition. After several years of development, its performance becomes more stable and reliable. Extant local modes detection algorithm in pathrate is based on statistic methodology histogram. This paper suggests a new algorithm for local modes detection based on ASH (Averaged Shifted Histogram). We have implemented this algorithm and will prove it can accomplish the same task as the original one with a better result.

  • PDF

A Fast Motion Estimation Algorithm Based on Multi-Resolution Frame Structure (다 해상도 프레임 구조에 기반한 고속 움직임 추정 기법)

  • Song, Byung-Cheol;Ra, Jong-Beom
    • Journal of the Institute of Electronics Engineers of Korea SP
    • /
    • v.37 no.5
    • /
    • pp.54-63
    • /
    • 2000
  • We present a multi-resolution block matching algorithm (BMA) for fast motion estimation At the coarsest level, a motion vector (MV) having minimum matching error is chosen via a full search, and a MV with minimum matching error is concurrently found among the MVs of the spatially adjacent blocks Here, to examine the spatial MVs accurately, we propose an efficient method for searching full resolution MV s without MV quantization even at the coarsest level The chosen two MV s are used as the initial search centers at the middle level At the middle level, the local search is performed within much smaller search area around each search center If the method used at the coarsest level is adopted here, the local searches can be done at integer-pel accuracy A MV having minimum matching error is selected within the local search areas, and then the final level search is performed around this initial search center Since the local searches are performed at integer-pel accuracy at the middle level, the local search at the finest level does not take an effect on the overall performance So we can skip the final level search without performance degradation, thereby the search speed increases Simulation results show that in comparison with full search BMA, the proposed BMA without the final level search achieves a speed-up factor over 200 with minor PSNR degradation of 02dB at most, under a normal MPEG2 coding environment Furthermore, our scheme IS also suitable for hardware implementation due to regular data-flow.

  • PDF

Distributed Routing Based on Minimum End-to-End Delay for OFDMA Backhaul Mobile Mesh Networks

  • Chung, Jong-Moon;Lee, Daeyoung;Park, Jong-Hong;Lim, Kwangjae;Kim, HyunJae;Kwon, Dong-Seung
    • ETRI Journal
    • /
    • v.35 no.3
    • /
    • pp.406-413
    • /
    • 2013
  • In this paper, an orthogonal frequency division multiple access (OFDMA)-based minimum end-to-end delay (MED) distributed routing scheme for mobile backhaul wireless mesh networks is proposed. The proposed scheme selects routing paths based on OFDMA subcarrier synchronization control, subcarrier availability, and delay. In the proposed scheme, OFDMA is used to transmit frames between mesh routers using type-I hybrid automatic repeat request over multipath Rayleigh fading channels. Compared with other distributed routing algorithms, such as most forward within radius R, farthest neighbor routing, nearest neighbor routing, and nearest with forwarding progress, simulation results show that the proposed MED routing can reduce end-to-end delay and support highly reliable routing using only local information of neighbor nodes.

Nonlinear Function Approximation of Moduled Neural Network Using Genetic Algorithm (유전 알고리즘을 이용한 모듈화된 신경망의 비선형 함수 근사화)

  • 박현철;김성주;김종수;서재용;전홍태
    • Proceedings of the Korean Institute of Intelligent Systems Conference
    • /
    • 2001.12a
    • /
    • pp.10-13
    • /
    • 2001
  • Nonlinear Function Approximation of Moduled Neural Network Using Genetic Algorithm Neural Network consists of neuron and synapse. Synapse memorize last pattern and study new pattern. When Neural Network learn new pattern, it tend to forget previously learned pattern. This phenomenon is called to catastrophic inference or catastrophic forgetting. To overcome this phenomenon, Neural Network must be modularized. In this paper, we propose Moduled Neural Network. Modular Neural Network consists of two Neural Network. Each Network individually study different pattern and their outputs is finally summed by net function. Sometimes Neural Network don't find global minimum, but find local minimum. To find global minimum we use Genetic Algorithm.

  • PDF

Redundancy Utilizations of Redundant Robot Manipulators Based on Configuration Control (형태제어에 기초한, 여유자유도를 갖는 로보트 머니퓰레이터의 여유자유도 이용에 관한 연구)

  • ;Homayoun Seraji
    • The Transactions of the Korean Institute of Electrical Engineers
    • /
    • v.41 no.4
    • /
    • pp.422-432
    • /
    • 1992
  • Previous investigations of redundant manipulators have often focussed on local optimization for redundancy resolution by using the Jacobian pseudoinverse to solve the instantaneous relationship between the joint and end-effector velocities. This paper establishes some new goals for redundancy resolution at position level by using configuration control approach which has been recently developed. Minimum gravity loading, joint limit avoidance, minimum sensitivity, maximum stiffness and minimum impulse are introduced as redundancy resolution goals. These new goals for redundancy resolution allow more efficient utilizations of the redundant joints based on the desired task requirements. Simple computer simulation examples are given for illustration.

  • PDF

On the Regional Background Levels of $CH_4$ Observed Peninsula in Korea during 1990~1992 (한국의 태안반도에서 관측된 $CH_4$의 지역적 배경농도에 관한 연구 -1990~1992년 자료를 중심으로-)

  • 정용승;이근준
    • Journal of Environmental Science International
    • /
    • v.1 no.2
    • /
    • pp.33-48
    • /
    • 1992
  • Since November 1990, the observations of methane (CH4) level have been carried out at Tae-ahn Peninsula (TAP) in Korea. Analysis on atmospheric data obtained in the period from November 1990 to August 1992 is carried out and the results are included in this study. We 임ole that CIL does not have a clear seasonal cycle with a minor maximum in August- september and with a minimum in June-July. The variations in monthly average level are much larger with 1765.01∼ 1857.21 pub (amplitude 92.20 ppb). The occurrence of a minimum in June-July is due to the inflow of the North Pacific air, an increase of OH radical and due to a decrease in CH4 emission from rice paddy. A maximum in August and September appears to result from an increase in organic materials in agriculture (rice paddy) and forests, inputs of local sources due to weak airflows, stagnation of the warm and moist air and from a decrease in OH radical.'rho present analysis indicates that according to CH4 data from Mongolia and from several sites in North Pacific TAP is influenced as much as 31 pub in average from the inputs of Chinese omission. When the atmospheric CH4 of TAP is compared with data observed at Korea National University of Education (KNU), the values of KNU are higher (127 ppb) than those of TAP. It is clear that air samples taken at KNU are influenced strongly by local sources in central Korea than those at TAP. According to analysis of trajectories and airflows, we find that there are 4 types in classification. Firstly, when an air flow is originated mainly in China values of CH4 gas are in medium ranges. Secondly, when an airflow is from both local (Korea) and China we find higher values. Thirdly, with an airflow from both local (Korea) and Japan origins medium values are recorded. Fourths)r, when an airflow of maritime origin arrives low values of atmospheric CH4 are observed at TAP.

  • PDF

High Resolution Wideband Local Polynomial Approximation Beamforming for Moving Sources (이동하는 음원에 적합한 고분해능 광대역 LPA 빔형성기법)

  • Park Do-Hyun;Park Gyu-Tae;Lee Jung-Hoon;Lee Su-Hvoung;Lee Kyun-Kyung
    • The Journal of the Acoustical Society of Korea
    • /
    • v.24 no.1
    • /
    • pp.1-10
    • /
    • 2005
  • This paper presents a wideband LPA (local polynomial approximation) beamforming algorithm that is appropriate for wideband moving sources. The Proposed wideband LPA algorithm adopts STMV (steered minimum variance) method that utilizes a steered covariance matrix obtained from multiple frequency components in one data snapshot, instead of multiple data snapshots in one frequency bin. The wideband LPA cost function is formed using STMV weight vector. The Proposed algorithm searches for the instantaneous DOA and angular velocity that maximize the wideband LPA cost function. resulting in a higher resolution performance than that of a DS LPA beamforming algorithm. Several simulations using artificial data and sea trial data are used to demonstrate the performance of the Proposed algorithm.

Genetic Algorithm with the Local Fine-Tuning Mechanism (유전자 알고리즘을 위한 지역적 미세 조정 메카니즘)

  • 임영희
    • Korean Journal of Cognitive Science
    • /
    • v.4 no.2
    • /
    • pp.181-200
    • /
    • 1994
  • In the learning phase of multilyer feedforword neural network,there are problems such that local minimum,learning praralysis and slow learning speed when backpropagation algorithm used.To overcome these problems, the genetic algorithm has been used as learing method in the multilayer feedforword neural network instead of backpropagation algorithm.However,because the genetic algorith, does not have any mechanism for fine-tuned local search used in backpropagation method,it takes more time that the genetic algorithm converges to a global optimal solution.In this paper,we suggest a new GA-BP method which provides a fine-tunes local search to the genetic algorithm.GA-BP method uses gradient descent method as one of genetic algorithm's operators such as mutation or crossover.To show the effciency of the developed method,we applied it to the 3-parity bit problem with analysis.