• Journal of Distribution Science
• /
• v.22 no.7
• /
• pp.23-32
• /
• 2024

Purpose: Increasingly limited environmental resources encourage all sectors to implement robust distribution systems, including Logistics Service Provider (LSP) as a company that manages customer logistics activities. However, efforts to achieve a robust distribution system have many challenges. To overcome these challenges, as a first step, LSP needsto classify and analyze the challenges faced and find solutions. Knowledge of the challengesin managing robust logisticsisstill not widely researched in developing countries. This paper explores existing research gaps in the region. Research design, data and methodology: The research enquiries used are a questionnaire and in-depth interviews. In the field study, surveys, observations, interviews related to robust logistics implementation in the LSP were carried out. Results: The results of the study show that although robust logistics is recognized as very important, understanding among LSPs is still very diverse. The main challengesfound in this study come from the economic aspect and the internal conditions of the organization. Conclusion: LSP is advised to carry out internal strengthening of the company, especially for economic and organizational aspects therefore they can implement robust and sustainability practices more intensively. LSP needs to have good financial support in order to implement the aspects on an ongoing basis.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.54 no.10
• /
• pp.500-506
• /
• 2005

With the advent of electric power systems moving to a deregulated retail electricity market environment, calculating distribution service tariffs has become a challenging theme for distribution industries and tariff regulators. As distribution business remains as a monopoly, it is necessary to be regulated. And as multiple distribution companies compete with each other, it would be efficient to adopt competition to the determination of distribution service tariffs. This paper proposes a method to calculate distribution service tariffs using yardstick regulation, which can lead to competition among multiple distribution companies. The proposed method takes into account not only recovering revenue requirements but also the advantages of the yardstick regulation based on long-term marginal costs of distribution network expansion algorithms. A computer simulation is carried out to illustrate effectiveness of the proposed method and it is estimated that the algorithm can be applied to compute the distribution service tariffs under retail electricity markets.

• Steel and Composite Structures
• /
• v.49 no.2
• /
• pp.181-196
• /
• 2023

Marine structures including offshore wind turbines (OWTs) always work under cyclic loads, which arouses much attention on the fatigue design. The tripod substructure is one of the typical foundation forms for fixed OWTs. The three-planar tubular Y-joint (3Y joint) is one of the important components in fatigue design as it is most likely to have cracks. With the existence of the multiplanar interaction effect, calculating the hot spot stress (HSS) of 3Y joints is complicated. To assist with fatigue design, the distributions of stress concentration factor (SCF) and multiplanar interaction factor (MIF) along weld toe curves induced by the out-of-plane bending moment are explored in this study. An FE analysis method was first developed and verified against experimental results. This method was applied to build a numerical database including 1920 FE models covering common ranges of geometric parameters. A parametric study has been carried out to reveal the distribution patterns of SCF and MIF. After multidimensional nonlinear fittings, SCF and MIF distribution formulas have been proposed. Accuracy and reliability checking prove that the proposed formulas are suitable for calculating the HSS of 3Y joints.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.16 no.9
• /
• pp.2927-2941
• /
• 2022

The primary task of machine fault diagnosis is to judge whether the current state is normal or damaged, so it is a typical binary classification problem with mutual exclusion. Mutually exclusive events and out-of-domain detection have one thing in common: there are two types of data and no intersection. We proposed a fusion model method to improve the accuracy of machine fault diagnosis, which is based on the mutual exclusivity of events and the commonality of out-of-distribution detection, and finally generalized to all binary classification problems. It is reported that the performance of a convolutional neural network (CNN) will decrease as the recognition type increases, so the variational auto-encoder (VAE) is used as the primary model. Two VAE models are used to train the machine's normal and fault sound data. Two reconstruction probabilities will be obtained during the test. The smaller value is transformed into a correction value of another value according to the mutually exclusive characteristics. Finally, the classification result is obtained according to the fusion algorithm. Filtering normal data features from fault data features is proposed, which shields the interference and makes the fault features more prominent. We confirm that good performance improvements have been achieved in the machine fault detection data set, and the results are better than most mainstream models.

• Communications for Statistical Applications and Methods
• /
• v.21 no.6
• /
• pp.539-559
• /
• 2014

We derive the exact distribution of summation for random samples from uniform distribution and then compare the exact distribution with the approximated normal distribution obtained by the central limit theorem. To check the similarity between two distributions, we consider five existing normality tests based on the difference between the target normal distribution and empirical distribution: Anderson-Darling test, Kolmogorov-Smirnov test, Cramer-von Mises test, Shapiro-Wilk test and Shaprio-Francia test. For the purpose of comparison, those normality tests are applied to the simulated data. It can sometimes be difficult to derive an exact distribution. Thus, we try two different transformations to find out which transform is easier to get the exact distribution in terms of calculation complexity. We compare two transformations and comment on the advantages and disadvantages for each transformation.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.11a
• /
• pp.621-624
• /
• 2003

The columns with large widths in out-of-plane direction fail showing the high nonlinearity of strain distribution. In order to predict the nonlinear behavior with reasonable accuracy in 2 dimensional analysis the material models taking this characteristic into account are indispensible. In this study equivalent softening model is developed which releases the same amount of energy at failure as that of 3-D analysis. Its validity is confirmed by comparing the analysis result with that of 3-D.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.17 no.3
• /
• pp.181-193
• /
• 1992

This paper shows the model of a consecutive-k-out-of-n :G system with common-cause outages. The objective is to analytically derive the mean operating time between failures for a non-repairable component system. The average failure time of a system and the system availability are also considered. Then, the model is extended to a system with repairable components and unrestricted repair, in which service times are exponentially distributed.

• Journal of the Korean Data and Information Science Society
• /
• v.8 no.2
• /
• pp.119-125
• /
• 1997

We handle the stochastic processes of independent and identically distributed random variables. But random variables are usually dependent among themselves in actual life. So in this paper, we find out a new process not satisfying Markov property. We investigate the probability mass functions and study on the probability of the first-passage time. Also we find out the average frequency of continuous successes in from 0 to n time.

• Proceedings of the KIEE Conference
• /
• 1997.11a
• /
• pp.3-5
• /
• 1997

The relation between electric current and magnetic field under three overhead transmission lines being operated was studied. It was examined for a difference each other in comparison with calculated value and measured value for current, magnetic field. With magnetic field equations made out, The magnetic field distribution around transmission lines had made to figure out with easy by load electric current value. Additionally, we are going to describe the distribution curve of magnetic exposure volume for KEPCO's T/L.

• Journal of Distribution Research
• /
• v.1 no.2
• /
• pp.173-198
• /
• 1996

Distribution of farm produce in Korea is known to be inefficient due to the numerous stages that exist in the distribution channel. This has resulted in dissatisfaction for both farmer and consuers; farmers sell their produce at low prices to middlemen while consumers pay high prices for them because of price increases that occur in the distribution chain. We apply Spengler's theory of double marginalization to show that price increases are inevitable as the length of the farm distribution chain increases. We then show that the negative effects of double marginalization can be contained by setting up a physical distribution center. The physical distribution center effectively reduces the stages in the distribution from 5 or 6 stages to 3 or 4 stages. We also lay out the design and major characteristics of the distribution center, as well as the expected cost savings.