• Journal of Ocean Engineering and Technology
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• v.8 no.1
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• pp.62-70
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• 1994

In order to estimate the detection range of a active SONAR system, the SONAR equation is commonly used. In this paper, an algorithm to calculate detection range in active SONAR system as function of SONAR depth and target depth is presented. For given SONAR parameters and environment, the transmission loss and background level are found, signal excess is computed. Using log-normal distribution, signal excess is converted to detection probability at each range. Then, the detection range is obtained by integrating the detection probability as function of range for each depth. The proposed algorithm have been applied to the case of omni-directional source with center frequency 30Hz for summer and winter sound profiles. It is found that the optimal search depth is the source depth since the detection range increase at source depth where the signal excess is maximized.

• Earthquakes and Structures
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• v.19 no.2
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• pp.79-90
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• 2020

4- and 8-storey reinforced-concrete frame buildings are analyzed under the suites of the near-fault pulse-like, and the corresponding spectrally equivalent far-fault ground-motion records. Seismic fragility curves for the slight, moderate, extensive, and complete damage states are developed, and the damage probability matrices, and the mean loss ratios corresponding to the Design Basis Earthquake and the Maximum Considered Earthquake hazard levels are compared, for the investigated buildings and sets of ground-motion records. It is observed that the spectrally equivalent far-fault ground-motion records result in comparable estimates of the fragility curve parameters, as that of the near-fault pulse-like ground-motion records. As a result, the derived damage probability matrices and mean loss ratios using two suites of ground-motion records differ only marginally (of the order of ~10%) for the investigated levels of seismic hazard, thus, implying the potential for application of the spectrally equivalent ground-motion records, for seismic fragility and risk assessment at the near-fault sites.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.9
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• pp.1055-1063
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• 1999

This paper present a conceptual possibilistic approach using fuzzy set theory to manage the uncertainties in the given reliability input date of the practical power system. In this paper, an algorithm is introduced to calculate the possibilstic reliability indices according to the degree of uncertainty in the given data. The probability distribution function can be transformed into an appropriate possibilstic representation using the probability-Possibility Consistency principle(PPCP) algorithm. In this the algorithm, the transformation is performation by making a compromise between the transformation consistency and the human updating experience. Fuzzy classifcation theory is applied to reduced the number of load data. The fuzzy classification method determines the closeness of load data points by assigning them to various clusters and then determening the distance between the clusters. The IEEE-RTS with 32-generating units is used to demonstrate the capability of the proposed algorithm.

• Communications of the Korean Mathematical Society
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• v.14 no.2
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• pp.405-423
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• 1999

We consider a statistical multiplexer model with finite buffer capacity and finite number of independent identical 3-state bursty voice sources. The burstiness of the sources is modeled by describing both two different active periods (at the rate of one packet perslot) and the passive periods during which no packets are generated. Assuming a mixture of two geometric distributions for active period and a geometric distribution for passive period and geometric distribution for passive period, we derive the recursive algorithm for the probability mass function of the buffer contents (in packets). We also obtain loss probability and the distribution of packet delay. Numerical results show that the system performance deteriorates considerably as the variance of the active period increases. Also, we see that the loss probability of 2-state Markov models is less than that of 3-state Markov models.

• ETRI Journal
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• v.40 no.5
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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.

• IE interfaces
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• v.12 no.2
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• pp.312-318
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• 1999

This paper considers the cell loss probability(CLP) in a multiplexer with the superposition of heterogeneous ON/OFF sources. The input traffic is composed of k classes. Traffic of class i is the superposition of M_(i) ON/OFF sources. Recently, the method based on the Markov modulated deterministic process(MMDP) is presented. Basically, it is the discretized model of stochastic fluid flow process(SFFP) and gives the CLP very fast, but under-estimates the CLP especially when the value of estimated CLP is very low. This paper develops the discretized model of Markov modulated Poisson process(MMPP). It is a special type of switched batch Bernoulli process(SBBP). Combining the transition probability matrix of MMDP and SBBP according to the state which is characterized by the arrival rate, this paper presents hybrid algorithm. The hybrid algorithm gives better estimate of CLP than that of MMDP and faster than SBBP.

• IE interfaces
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• v.11 no.3
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• pp.77-87
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• 1998

Intelligent Peripheral(IP) system is to provide specialized resource functions (SRF) such as playing announcement, collecting user information, and receiving messages in the Advanced Intelligent Network (AIN). We analyze the call processing capacity of an AIN IP system being developed in ETRI through an extensive simulation using SLAM II under a variety of AIN service scenarios. We consider televoting (VOT) and universal personal telecommunication (UPT) services which are to be provided at the fit implementation of the AIN in Korea. As the performance criteria to determine the call processing capacity, processor utilization, delay and call loss probability are considered. It turns out that the major processor called SAMP is the bottleneck processor, the service response delay dominates the delay performance, and the call loss probability becomes the primary criterion in determining the call processing capacity of the AIN IP system. It is also shown that the call processing capacity of the AIN IP system is determined by the utilization of the processor and the delay performance when the VOT ratio is below 70 percent but it is determined by the call loss probability due to the lack of service channels for providing the SRF operations.

• KIEE International Transactions on Power Engineering
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• v.3A no.1
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• pp.35-41
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• 2003

To ensure resource adequacy in restructured electricity markets, policymakers have adopted installed capacity (ICAP) markets in some regions of the United States. These markets ensure that adequate generation exists to satisfy regional Loss of Load Probability(LOLP) criterion. Since the incentives created through ICAP mechanisms directly impact new generation and transmission investment decisions we examine one important factor that links ICAP markets with LOLP calculations;, determining the amount of ICAP credit assigned to particular generation units. First, we review and critique the literature on electric power systems' market failure resulting from demand exceeding supply. We then summarize the method of computing (the LOLP) as a means of assessing reliability and relate this method to ICAP markets. We find that only the expected value of available generation is used In current ICAP markets while ignoring the second and higher order moments, which tends to mis-state the ICAP value of a specific resource. We then consider a proposal whose purpose is to avoid this ICAP assignment issue by switching from ICAP obligations to options. We find that such a proposal may fail to not provide the benefits claimed and suffers from several practical difficulties. Finally, we conclude with some policy recommendations and areas for future research.

• Journal of Communications and Networks
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• v.7 no.3
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• pp.337-352
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• 2005

In this paper, a fuzzy logic implementation of the random early detection (RED) mechanism [1] is presented. The main objective of the proposed fuzzy controller is to reduce the loss probability of the RED mechanism without any change in channel utilization. Based on previous studies, it is clear that the performance of RED algorithm is extremely related to the traffic load as well as to its parameters setting. Using fuzzy logic capabilities, we try to dynamically tune the loss probability of the RED gateway. To achieve this goal, a two-input-single-output fuzzy controller is used. To achieve a low packet loss probability, the proposed fuzzy controller is responsible to control the $max_{p}$ parameter of the RED gateway. The inputs of the proposed fuzzy controller are 1) the difference between average queue size and a target point, and 2) the difference between the estimated value of incoming data rate and the target link capacity. To evaluate the performance of the proposed fuzzy mechanism, several trials with file transfer protocol (FTP) and burst traffic were performed. In this study, the ns-2 simulator [2] has been used to generate the experimental data. All simulation results indicate that the proposed fuzzy mechanism out performs remarkably both the traditional RED and Adaptive RED (ARED) mechanisms [3]-[5].

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4C
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• pp.550-558
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• 2004

In order to design network node for guaranteeing availability against network based DoS attack, some restrictions such as the relationship analysis on upper and lower layer bandwidth, buffer capacity, attack resources, a number of attack session and loss probability are analyzed. And then, to make good use of network resource, the relationship between required resources for satisfying loss probability and cost is discussed. The results of this study are expected to be applied to the effective security node design against network DoS.