• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.11
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• pp.476-484
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• 2006

The failure prediction and preventive maintenance for the equipment of nuclear power plant area using reliability-centered maintenance have been grown. On the other hand, the maintenance for power distribution system consists of time-based maintenance mainly. In this paper, the new maintenance algorithms for power distribution system are developed considering reliability indices. First of all, Time-varying failure rates are extracted from data accumulated at KEPCO using exponential distribution function and weibull distribution function. Next, based on the extracted failure rate, reliability for real power distribution system is evaluated for applying the effective maintenance algorithm which is the analytic method deciding the maintenance point of time and searching the feeder affecting the specific customer. Also the algorithm deciding the maintenance priority order are presented based on sensitivity analysis and equipment investment plan are analyzed through the presented algorithm at real power distribution system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.8
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• pp.454-460
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• 2004

The effects of surge arresters for protection of transmission systems against direct lightning strokes have already been reviewed using Electromagnetic Transients Program(EMTP). Distribution lines are spanned in much larger area than transmission lines, and therefore, are more susceptible to lightning strokes. We have modelled the 22.9kV underground distribution cable systems that have arresters and grounding wires. And this paper analyzes the overvoltages on underground distribution cable systems when direct lightning strokes strike on the overhead grounding wire using EMTP. Then we investigated that (1) the effects of lightning stroke according to underground distribution cable length (2) voltages at the riser pole and at the cable terminal according to installation of arrester. This study will provide insulation coordination methods for reasonable systems design in 22.9kV underground distribution cable systems.

• Genomics & Informatics
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• v.4 no.2
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• pp.65-70
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• 2006

Peptide mass mapping is the matching of experimentally generated peptides masses with the predicted masses of digested proteins contained in a database. To identify proteins by matching their constituent fragment masses to the theoretical peptide masses generated from a protein database, the peptide mass fingerprinting technique is used for the protein identification. Thus, it is important to know the theoretical mass distribution of the database. However, few researches have reported the peptide mass distribution of a database. We analyzed the peptide mass distribution of non-redundant protein sequence database in the NCBI after digestion with 15 different types of enzymes. In order to characterize the peptide mass distribution with different digestion enzymes, a power law distribution (Zipfs law) was applied to the distribution. After constructing simulated digestion of a protein database, rank-frequency plot of peptide fragments was applied to generalize a Zipfs law curve for all enzymes. As a result, our data appear to fit Zipfs law with statistically significant parameter values.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2079-2088
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• 2009

The optimal operation in distribution system is to select tie switches considering important elements(Load balance, Loss minimization, Voltage drop, Restoration index..) in distribution system. Optimal Tie Switches Selection is very important in operation of distribution system because that is closely related with efficiency and reliability. In this paper, a new algorithm considering important elements is proposed to find optimal location of tie switches. In the case study, the proposed algorithm has been testified using real distribution network of KEPCO for verifying algorithm and complex network for applying future distribution network.

• Tunnel and Underground Space
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• v.17 no.3 s.68
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• pp.197-202
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• 2007

In this study, design parameters were determined statistically with and without consideration of original distribution characteristics. Obtained parameters were applied to test numerical analysis and the results were compared. Distribution characteristics of statistically treated parameters show the similar characteristics of original distribution. Mean values show more than 19% of errors between the two cases. Regarding the characteristics as normal distribution can cause distorted results, it is proper to consider the original distribution characteristics of the parameters.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.1 s.232
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• pp.22-29
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• 2005

A material cloud method, which is a new topology optimization method, is presented. In MCM, an optimal structure can be found out by manipulating sizes and positions of material clouds, which are lumps of material with specified properties. A numerical analysis for a specific distribution of material clouds is carried out using fixed background finite element mesh. Optimal material distribution can be element-wisely extracted from material clouds' distribution. In MCM, an expansion-reduction procedure of design domain for finding out better optimal solution can be naturally realized. Also the convergence of material distribution is faster and well-defined material distribution with fewer intermediate densities can be obtained. In addition, the control of minimum-member sizes in the material distribution can be realized to some extent. In this paper, basic concept of MCM is introduced, and formulation and optimization results of MCM are compared with those of the traditional density distribution method(DDM).

• Communications for Statistical Applications and Methods
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• v.31 no.3
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• pp.263-277
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• 2024

This paper proposes new parameterizations of the tilted beta binomial distribution, obtained from the combination of the binomial distribution and the tilted beta distribution, where the beta component of the mixture is parameterized as a function of their mean and variance. These new parameterized distributions include as particular cases the beta rectangular binomial and the beta binomial distributions. After that, we propose new linear regression models to deal with overdispersed binomial datasets. These new models are defined from the proposed new parameterization of the tilted beta binomial distribution, and assume regression structures for the mean and variance parameters. These new linear regression models are fitted by applying Bayesian methods and using the OpenBUGS software. The proposed regression models are fitted to a school absenteeism dataset and to the seeds germination rate according to the type seed and root.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.5
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• pp.238-246
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• 2002

Utilities are trying to install the equipment of high quality to avoid deterioration of supply reliability. In addition, many sectionalizing switches which can decrease the total outage value for a fault are installed for the same reason. Therefore, utilities are interested in stun dards and criteria for installing switches to optimize the total cost on distribution systems. The affect of sectionalizing switches installed on distribution feeder is gradually decreased because the failure rate on distribution feeder is decreased. Also the automation for distribution systems is widely applied for the efficient operation. Therefore, the renewal for installation standards of sectionalizing switches Is required to reflect the current operation situation. The variable data is used to consider the KEPCO's real situation of distribution feeder as follows; the feeder capacity, connecting rate, feeder length, failure rate of distribution feeder, the failure rate of switches, perception time of feeder fault, the restoration time for a faulted section, the transfer time to other feeders, and the switching time. In this study, We propose equations which can determine the number of sectionalizing switches for minimizing the outage and switch installation cost.

• KIEE International Transactions on Power Engineering
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• v.4A no.1
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• pp.11-17
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• 2004

It becomes difficult and high in cost to construct new ducts and/or tunnels for power cables in domestic areas. This paper presents possible strategy of an HTS distribution cables for distributing electric power in local areas as niche marketing. Reflected were its important distinction such as system configuration, rationale, establishment of strategy and considerably high economical efficiency compared with present underground cables. In this paper, applicable important items by using HTS distribution cables in water pumping powerhouse and distribution substation as example objective regions were reviewed. Based on this, the following items on distribution HTS system are examined. (I)A review of constructing a model system to introduce high temperature superconducting distribution cables to objective areas is presented. (2)The strategy to capture HTS distribution cable in water pumping powerhouse and distribution substation as niche marketing regions were reviewed. (3)In concrete, system configuration, rationale, establishment of strategy and considerably high economical efficiency are reviewed between existing cable and HTS one.

• Communications for Statistical Applications and Methods
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• v.4 no.1
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• pp.229-241
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• 1997

We consider discrimination curve and minimum dwell time for Poisson distribution and Poisson-power function distribution. Let the random variable X has Poisson distribution with mean .lambda.. For the hypothesis testing H$\_$0/:.lambda. = t vs. H$\_$1/:.lambda. = d (d$\_$0/ if X.leq.c. Since a critical value c can not be determined to satisfy both types of errors .alpha. and .beta., we considered discrimination curve that gives the maximum d such that it can be discriminated from t for a given .alpha. and .beta.. We also considered an algorithm to compute the minimum dwell time which is needed to discriminate at the given .alpha. and .beta. for the Poisson counts and proved its convergence property. For the Poisson-power function distribution, we reject H$\_$0/ if X.leq..'{c}.. Since a critical value .'{c}. can not be determined to satisfy both .alpha. and .beta., similar to the Poisson case we considered discrimination curve and computation algorithm to find the minimum dwell time for the Poisson-power function distribution. We prosent this algorithm and an example of computation. It is found that the minimum dwell time algorithm fails for the Poisson-power function distribution if the aiming error variance .sigma.$\^$2/$\_$2/ is too large relative to the variance .sigma.$\^$2/$\_$1/ of the Gaussian distribution of intensity. In other words, if .ell. is too small, we can not find the minimum dwell time for a given .alpha. and .beta..