• 한국통신학회논문지
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• 제25권7B호
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• pp.1167-1177
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• 2000

본 논문에서는 접속노드와 무선채널로 구성되는 무선 ATM(Asynchronous Transfer Mode) 접속망의 셀 손실율과 호손율간의 관계를 도출하였다. 이를 위해 우선 ATM 접속망의 트래픽 모델을 셀 레벨, 버스트셀 레벨 및 호접속레벨로 구부하여 분석하였고, 무선접속노드의 CLR(Cell Loss RAtio) 성능을 나타낼 수 있는 수식을 VBR(Variable Bit Rate) 및 램덤 트래픽으로 구분하여 제시하였으며 무선채널에 대해서는 랜덤에러 및 버스트 에러환경으로 구분하여 CLR 성능을 나타낼 수 있는 수식을 유도하였다. 그리고 접속노드와 무선채널의 CLR을 나타내는 수식을 이용하여 무선 ATM 접속망의 CLR 성능을 나타내는 수식을 도출한 후 접속망의 트래픽 성능평가를 위해 VBR, CBR 및 랜덤 트래픽 형태별로 CLR과 호손율간의 관계를 분석하였다. 즉 이용도와 CLR간의 관계로부터 셀 레벨의 접속망 CLR 목표치가 정해지면 이용도 및 접속 회선수를 구할 수 있으며 이를 호 접속레벨의 Erlang-B 관계식과 관련시켜서 CLR과 호손율간의 관계를 제시하였다.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2003년도 하계학술대회
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• pp.321-324
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• 2003

현재 이동전화 Network 유선구간의 음성회선 산출기법은 얼랑(Erlang) B 이론을 그 바탕으로 하고 있다. 그리고 이러한 얼랑 B이론은 가입자 시도호의 특성이 포아송(Poisson)분포를 하고있음을 기본가정으로 하고 이를 바탕으로 서비스제공자가 목표하는 호손율을 달성하기 위해 필요한 회선수를 얼랑 B 테이블로 제시하고 있다. 본 논문은 실제가입자의 트래픽특성(분포) 및 얼랑 B 이론의 실측특성을 분석하여 이러한 얼랑 B 모델이 상용망에서 적정하게 적용될수 있는지를 검증하였으며 이러한 실측검증을 바탕으로 서비스 제공자의 목표호손율을 일정한 확률(신뢰도) 범위에서 보장하는 보정된 얼랑B 테이블을 제시한다.

• Journal of Mechanical Science and Technology
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• 제16권1호
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• pp.60-74
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• 2002

In this study, normal, log-normal, triangular, uniform. Weibull, Erlang and unit beta probability density functions are tried to represent the behaviour of frequency distributions of workpiece dimensions collected from various manufacturing firms. Among the distribution functions, the unit beta distribution function is found to be the best fit using the chi-square test of fit. An attempt is made for the adoption of the unit beta model to x-bar charts of quality control in manufacturing. In this direction, upper and lower control limits (UCL and LCL) of x-bar control charts of dimension measurements are estimated for the beta model, and the observed differences between the beta and normal model control limits are discussed for the measurement sets.

• 산업경영시스템학회지
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• 제17권31호
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• pp.59-72
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• 1994

This paper deals with ordering policies of consumable goods which have large demand rates in a multi-level distribution system. The system we are concerned consists of one Central Distribution Center(CDC) and N non-identical Regional Distribution Centers(RDCs) which have different demand rates, minimum fillrates, leadtimes, etc. The customer demand on the RDC is stationary poisson and the RDCs demand on the CDC is superposition of Q-stage Erlang distributions. We approximate the RDCs and CDC demand distribution to nomal in order to enhance the efficiency of algorithm. The relevant costs include a fixed ordering cost and inventory holding cost, and backorder cost. The objective is to find a continuous-review ordering policy that minimizes the expected average costs under constraints of minimum fill rates of RDCs and maximum allowable mean delay of CDC. We developed an algorithm for determining the optimal ordering policies of the CDC and the RDCs. We verified and compared the performance of the algorithm through the simulation using the algorithm result as the input parameters.

• 대한전자공학회논문지
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• 제25권3호
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• pp.335-342
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• 1988

In this paper, we proposed a new algorithm for EMG low frequency analysis. Through the power spectrum analysis of Gaussian's, Gamma's and Erlang's PDF(probability density function) based on the proposed algorithm, the proper PDF of IPI (inter pulse interval) representing the firing rate of muscle was suggested. In order to verify the proposed algorithm EMG signals of masseter and biceps muscle were detected by surface electrode and its power spectrum analysis was performed. The experimental results are compared with the computer simulaiton. As a result, the masseter muscle's IPI was fitted by Gamma PDF, having a 10Hz fundamental frequency including n(1+\ulcornerfp high harmnic frequency on 10% MVC(maximum voluntary contaraction). And the biceps muscle's IPI was fitted by Gaussian PDF, also it have a 14Hz fundamental frequency.

• 산업공학
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• 제18권3호
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• pp.333-342
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• 2005

In this paper, we propose an efficient forecasting methodology of the mid and long-term frequency demand in Korea. The methodology consists of the following three steps: classification of basic service group, calculation of effective traffic, and frequency forecasting. Based on the previous studies, we classify the services into wide area mobile, short range radio, fixed wireless access and digital video broadcasting in the step of the classification of basic service group. For the calculation of effective traffic, we use the measures of erlang and bps. The step of the calculation of effective traffic classifies the user and basic application, and evaluates the effective traffic. Finally, in the step of frequency forecasting, different methodology will be proposed for each service group and its applications are presented.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2001년도 가을 학술발표논문집 Vol.28 No.2 (3)
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• pp.121-123
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• 2001

최근 이동 통신의 급격한 성장으로 인하여 동일한 통신 서비스간의 간섭 뿐 아니라 서로 다른 서비스간의 간섭 문제가 통신 서비스의 품질을 저하시키는 주된 요인으로 작용하고 있다. 특히, CDMA-based 시스템은 간섭에 의해 용량이 제한되므로 CDMA-based 시스템인 기존의 IS-95 및 PCS 서비스, 그리고 차세대 이동 통신인 IMT-2000/CDMA 시스템의 용량 개선을 위한 연구 및 효율적인 무선망 설계를 위한 연구가 필요하다. 본 연구에서는 IMT-2000/CDMA 시스템의 효율적인 링크 분석(Link Analysis)을 하는데 필요한 시스템 성능 평가와 시스템 통화용량을 산출하는 프로그램을 개발하고자 한다. 여기서, 시스템 성능을 예측하기 위해서는 신호 대 잡음 전력비 (E$_{b}$N$_{o}$ )의 개념이 요구된다. 시스템 통화용량은 잡음 특성이 매우 이상적인 상태를 기준으로 하여 역방향 최대 용량을 산정하는 Pole Capacity 산출 방식과 호차단율(B1ocking Probability)로부터의 통계적 산출 방법인 Erlang Capacity 산출 방식을 적용한다.

• 충청수학회지
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• 제21권4호
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• pp.501-510
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• 2008

The distribution of the sum of n independent random variables having exponential distributions with different parameters ${\beta}_i$ ($i=1,2,{\ldots},n$) is given in [2], [3], [4] and [6]. In [1], by using Laplace transform, Jasiulewicz and Kordecki generalized the results obtained by Sen and Balakrishnan in [6] and established a formula for the distribution of this sum without conditions on the parameters ${\beta}_i$. The aim of this note is to present a method to find the distribution of the sum of n independent exponentially distributed random variables with different parameters. Our method can also be used to handle the case when all ${\beta}_i$ are the same.

• 산업경영시스템학회지
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• 제18권34호
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• pp.139-146
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• 1995

This study is concerned with cost analysis in periodic maintenance policy. Generally periodic maintenance policy in which item is repaired periodic interval times. And in the article minimal repair is considered. Minimal repair means that if a unit fails, unit is instantaneously restored to same hazard rate curve as before failure. In the paper periodic maintenance policy with minimal repair is as follows; Operating unit is periodically replaced in periodic maintenance time, if a failure occurs between minimal repair and periodic maintenance time, unit is replaced by a spate until the periodic time comes. Also unit undergoes minimal repair at failures in minimal-repair-for-failure interval. Then total expected cost per unit time is calculated according to maintenance period and scale parameter of failure distribution. Total cost factors ate included operating, fixed, minimal repair, periodic maintenance and replacement cost Numerical example is shown in which failure time of system has erlang distribution.

• ETRI Journal
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• 제40권5호
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• pp.624-633
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• 2018

Fair bandwidth allocation (FBA) has been studied in optical burst switching (OBS) networks, with the main idea being to map the max-min fairness in traditional IP networks to the fair-loss probability in OBS networks. This approach has proven to be fair in terms of the bandwidth allocation for differential connections, but the use of the ErlangB formula to calculate the theoretical loss probability has made this approach applicable only to Poisson flows. Furthermore, it is necessary to have a reasonable fairness measure to evaluate FBA models. This article proposes an approach involving throughput-based-FBA, called TFBA, and recommends a new fairness measure that is based on the ratio of the actual throughput to the allocated bandwidth. An analytical model for the performance of the output link with TFBA is also proposed.