• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.509-511
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• 2001

In the competitive electricity market, various pricing methods are developed and practiced in many countries. Among these pricing methods, marginal loss factor(MLF) can be applied to reflect the marginal cost of network losses. For the calculation of MLF, power flow method has been used. However, it shows some shortcomings such as necessity of regional reference node, and absence of an ability to consider network constraints. The former defect might affect adversely to the equity of market participants and the latter might generate an inappropriate price signal. To overcome these defects, the utilization of optimal power flow(OPF) is suggested in this paper. 30-bus system is used for the case study to compare the MLF by the power flow and the OPF method for 24-hour dispatching and pricing.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.797-799
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• 1997

This paper presents an operation and planning model of integrated energy systems which consist of small scale cogeneration systems, thermal accumulator, ice storage and electrical energy storage systems. In the proposed planning model, an optimization of total cost which contains investment, operation, thermal shortage and salvage costs has carried out with the maximum principle based on the lifetime of each system component and unit price per capacity. From this model, optimal investment capacity per annum can be determined during the studied periods using the marginal costs according to the operation characteristics of each system component.

• Journal of the Korea Safety Management & Science
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• v.2 no.3
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• pp.27-36
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• 2000

The Robust Design method uses a mathematical tool called orthogonal arrays to study a large number of decision variables with a small number of experiments. It also uses a new measure of quality, called signal-to-noise (S/N) ratio, to predict the quality from the customer's perspective. Thus, the most economical product and process design from both manufacturing and customers' viewpoints can be accomplished at the smallest, affordable development cost. Many companies, big and small, high-tech and low-tech, have found the Robust Design method valuable in making high-quality products available to customers at a low competitive price while still maintaining an acceptable profit margin. A study to analyze and solve problems of a biochemical process experiment has presented in this paper. We have taken Taguchi's parameter design approach, specifically orthogonal array, and determined the optimal levels of the selected variables through analysis of the experimental results using S/N ratio.

• Korean Journal of Agricultural Science
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• v.23 no.2
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• pp.261-271
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• 1996

Korean government has pursued measure of promoting specialized full time farmers, one hundred fifty thousand by 2001, along with "New Agricultural Policy" begining since year 1993, so as to improve agricultural structure depressed by urbanization and industrialization and also under pressure for agricultural imports liberlization. Objective of the study was to estimate optimal farming size for selected cash crops and livestocks aimed at farm income of more than fifty million won at the year 2001. Estimated items were eighteen fann models of four area for cash crops and nine models of three kind livestocks. Optimal fann size was estimated from the data collected through ninety nine fann household survey for farming result in 1993. and developed computer model on changing farm size estimation related on price change. Those results is espected to utilize as basic reference for promoting specialized full time farmers proposed by the New Agricultural Policy.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.3
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• pp.41-48
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• 2011

Recently, the increasing power of distributors has given them the opportunity of introducing private brand (PB) products. Based on the game theory, this study analyzes the decision making of a distributor regarding the optimal pricing and quality strategies for the PB product. By analyzing the game model, it is shown that the pricing mechanism heavily depends not only on the market power of the distributor but on the quality of the PB product. It is also shown that, counter intuitively, as the market power of the distributor increases, the optimal quality of the PB product should be decreased.

• Journal of Korean Institute of Industrial Engineers
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• v.13 no.1
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• pp.31-38
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• 1987

This paper is concerned with the multiple unit auction under the following assumptions: 1) multiple identical objects are to be sold to the highest bidders, but a bidder may obtain at most one, 2) each bidder has a fixed reservation value and draws his reservation value independently in the same distribution, 3) The greater a bidder's reservation value is, the more a bidder will bid for the object, and 4) a bidder will bid when his expected profit is more than zero. The purpose of this paper is to design the optimal auctions, in terms of the reserve price and entry fee, that can be applied in any types of multiple unit auctions under the above assumptions. Further, auctioneer's expected revenue and profit, and all the winners' expected profit are analyzed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.7-15
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• 2012

In this paper a process of determination for thyristors operating with optimal angle is described. The proposed method is based on the trade-off between the cost(due to rating and loss) and controllability of the system. Large control angle increases controllability of HVDC system and also increase the rating of the system which leads to a high price. Therefore it is important to determine a control angle at a first step of design procedure. This paper shows a rating trend of C.Tr, Valve and Filter due to control angle variation, and then introduces a determination process of the HVDC operating angle.

• Proceedings of the Korean Society for Quality Management Conference
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• 2006.04a
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• pp.334-337
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• 2006

This paper considers the problem of selecting the most profitable process mean for production processes where measurement errors exist in inspection systems. For such situations, a sequential inspection procedure is proposed to reduce measurement errors. The decision to accept, reject, or take an additional inspection of an item is made at every measurement point until the number of repeated measurements reaches its upper bound. An expected profit model is constructed and the optimal process mean, the cut-off values, and the upper bound of the number of repeated measurements are obtained when accepted(rejected) items are sold at regular(reduced) price. A numerical study is performed to investigate the performance of the proposed procedure.

• Journal of Korean Society for Quality Management
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• v.51 no.2
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• pp.171-184
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• 2023

Purpose: First, this paper suggests an alternative approach to find optimal portfolio (stocks, bonds and ESG stocks) under the maximizing utility of investors. Second, we include ESG stocks in our optimal portfolio, and compare improvement of welfares in the case with and without ESG stocks in portfolio. Methods: Our main method of analysis follows Brennan et al(2002), designed under the continuous time framework. We assume that the dynamics of stock price follow the Geometric Brownian Motion (GBM) while the short rate have the Vasicek model. For the utility function of investors, we use the Power Utility Function, which commonly used in financial studies. The optimal portfolio and welfares are derived in the partial equilibrium. The parameters are estimated by using Kalman filter and ordinary least square method. Results: During the overall analysis period, the portfolio including ESG, did not show clear welfare improvement. In 2017, it has slightly exceeded this benchmark 1, showing the possibility of improvement, but the ESG stocks we selected have not strongly shown statistically significant welfare improvement results. This paper showed that the factors affecting optimal asset allocation and welfare improvement were different each other. We also found that the proportion of optimal asset allocation was affected by factors such as asset return, volatility, and inverse correlation between stocks and bonds, similar to traditional financial theory. Conclusion: The portfolio with ESG investment did not show significant results in welfare improvement is due to that 1) the KRX ESG Leaders 150 selected in our study is an index based on ESG integrated scores, which are designed to affect stability rather than profitability. And 2) Korea has a short history of ESG investment. During the limited analysis period, the performance of stock-related assets was inferior to bond assets at the time of the interest rate drop.

• Journal of Korea Port Economic Association
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• v.38 no.3
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• pp.15-28
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• 2022

Bunkering refers to the supply of bunker fuel necessary for the ship operation, as well as minimizing the price and supply cost of fuel itself, and includes supplying good quality fuel oil in a timely manner and at the optimal port. Bunkering is an important criterion in terms of cost for shipping companies because bunkering involves a significant cost to the purchaser of bunkering from the time of initial purchase. This study aims to prioritize selection criteria for tramper companies to call port for bunkering. For this study, the variables were selected by analyzing the common criteria such as price, location, bunker quality and service and infrastructure etc. employed in previous studies. The AHP method was employed to prioritize the criteria in order. As a result of the analysis, the high level factors appeared in the order of price, location, bunkering quality and port service and infrastructure factors. The importance of price criterion and location criterion was found to be high. In the low level criterion of price, the bunker price per MT was ranked first in importance. In terms of location criteria, the location on the main trade route was high. In the low criteria of bunker quality and port service, the bunkering available types and bunker quality were found to be important factors, and in the low level criteria of infrastructure, anchorage and availability of bunkering during loading and discharging and port security factors were found to be important criteria. This study provides the guidelines for research designed to compare the bunkering port selection factors and to derive their importance suggesting the ways to enhance competitiveness as a bunkering port.