• Journal of Welding and Joining
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• 제21권3호
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• pp.30-34
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• 2003

This paper describes the heat distribution characteristics of ASTM A131DH36 high tensile steel for ship structures in 5㎾ $CO_2$ laser welding. In general, high energy of laser beam concentrates on the small area of the weldment instantaneously; therefore, this heat transfer mechanism induces the rapid changes of temperature and mechanical characteristics in laser welds this mechanism. So temperature distribution analysis is important to understand mechanical characteristics of laser welds. Authors have conducted finite element simulation to analyze the heat distribution characteristics in laser welds. The result of simulation has been verified by comparing with the metallurgical experiment result. From the result of this study, we can accurately predict the heat distribution characteristics in laser welds by using numerical simulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.38-40
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• 2008

Distribution of Permanent magnet used in the spindle motor on the ODD is arranged by magnetizer. In general, permanent magnet is putted between yoke and back yoke of magnetizer so that symmetric magnetization distribution. But the magnet has unsymmetric magnetization distribution because of eccentricity of the yoke in mass production. So, in this paper we discuss the effect of asymmetric magnetization distribution on back EMF and cogging torque of the spindle motor.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.1-5
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• 2014

When renewable sources are connected to the distribution network in the form of a distributed generators(DGs), the effect of intermittent output appears as voltage fluctuation. The surplus power at the consumer ends results in the reverse power flow to the distribution network. This reverse power flow causes several problems to the distribution network such as overvoltage. Application of the reactive power control equipment and power flow control by means of BTB inverter have been suggested as the general solutions to overcome the overvoltage, but they are not economically feasible since they require high cost devices. Herein, we suggest the feeder loop line switch control method to solve the problem.

• Communications for Statistical Applications and Methods
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• 제25권5호
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• pp.569-575
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• 2018

Pareto distribution is important to analyze data in actuarial sciences, reliability, finance, and climatology. In general, unknown parameters of the Pareto distribution are estimated based on the maximum likelihood method that may yield inadequate inference results for small sample sizes and high percent censored data. In this paper, a new approach based on the regression framework is proposed to estimate unknown parameters of the Pareto distribution under the progressive Type-II censoring scheme. The proposed method provides a new regression type estimator that employs the spacings of exponential progressive Type-II censored samples. In addition, the provided estimator is a consistent estimator with superior performance compared to maximum likelihood estimators in terms of the mean squared error and bias. The validity of the proposed method is assessed through Monte Carlo simulations and real data analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.6-8
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• 2001

This paper covers general recommendations for top-oil temperature rising of mineral-oil-immersed power distribution transformer rated 100kVA and less, manufactured in Korea. In order to analyze the top-oil temperature rising due to the distribution transformer loading we performed experiments for oil-immersed distribution transformer, manufactured in domestic at KERI(Korea Electrical Research Institute) from December 2000 to May 2001. The magnitude of loading were changed, and the top-oil temperatures for each time were measured. Finally, we present the overload criteria of distribution transformer for summer and winter season in domestic. respectively.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2000년도 학술발표회 발표논문집
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• pp.352-358
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• 2000

The objective of this study is to derive optimal design floods by the Wakeby distribution using the probability weighted moments. parameters for the Wakeby distribution were estimated by the probability weighted moments for the annual flood flows of the applied watersheds. Design floods obtained by the Wakeby and GEV distributions were compared by the relative mean errors, relative absolute errors and root mean square errors. In general, it has shown that the design floods by the Wakeby distribution using the methods of the probability weighted moments are closer to those of the observed data in comparison with those obtained by the GEV distribution.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2280-2285
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• 2008

A general flow distribution model and a simple process of numerical analysis, which can be applied to multi-pass systems with manifolds, are presented. Correlations are derived from the discrete model, and numerically calculated using a modified equal pressure method. The predicted pressure distribution agrees well with the available experimental results of other researchers with the average error less than 2% for 10 branch manifolds, and 4% for 20 branch manifolds. A parametric study is performed to demonstrate the effect on the flow distribution.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2000년도 추계학술대회 논문집
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• pp.165-173
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• 2000

Analytic models have been developed to solve integrated production-distribution problems in supply chain management (SCM). As one of major constraints in analytic models, capacity, which is the total operation time in this paper has mostly been known or disregarded assuming infinite capacity. Also, as major factors, machine processing time to fabricate or assemble a part or product at a certain machine center in production system and vehicle processing time to deliver a product to a customer by a certain vehicle in distribution system have been fixed and regarded as a static factor, But in the real systems significant differences exit between capacity and the required time to achieve the production-distribution plan and between processing time and consumed time to process a part or product. In this paper, capacity and processing times in the analytic model are considered as dynamic factors and adjusted by the results from independently developed simulation model, which includes general production-distribution characteristics. Through experiments, we obtain the more realistic solutions reflecting stochastic natures by performing the iterative analytic-simulation procedure.

• 대한안전경영과학회지
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• 제4권3호
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• pp.59-66
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• 2002

This paper presents accelerated life tests for Type I censoring data under probabilistic stresses. Probabilistic stress, S, is the random variable for stress influenced by test environments, test equipments, sampling devices and use conditions. The hazard rate, $\theta$ is a random variable of environments and a function of probabilistic stress. In detail, it is assumed that the hazard rate is linear function of the stress, the general stress distribution is a gamma distribution and the life distribution for the given hazard rate, $\theta$is an exponential distribution. Maximum likelihood estimators of model parameters are obtained, and the mean life in use stress condition is estimated. A hypothetical example is given to show its applicability.

• Journal of Astronomy and Space Sciences
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• 제40권2호
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• pp.67-77
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• 2023

The Titius-Bode's relation has been historically successful in predicting the location of Ceres in the solar system, while its physical basis remains hidden. In this study, we attempt to answer the question of whether the Titius-Bode's relation is universally valid for exoplanetary systems with plural exoplanets. For this purpose, we statistically study the distribution of the ratio of the orbiting periods of two planets in 32 exoplanetary systems hosted by a single star. We only consider the period ratios derived from exoplanets orbiting a single star since celestial objects under investigation are kept as simple as possible and free from uncertainties such as the mass of the host star. We find that the distribution of period ratios of two exoplanets appears inconsistent with that derived from the Titius-Bode's relation using the χ² test. We also found that the distance distribution in exoplanetary systems unlikely follows the uniform distribution or the Poisson's distribution. It is noted, however, that more rigorous statistical tests should be carried out to reach a more certain conclusion.