• Industrial Engineering and Management Systems
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• v.15 no.4
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• pp.354-363
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• 2016

Due to uncertain environment, various parameters such as price, queuing length, warranty, and so on influence on inventory models. In this paper, an inventory-queuing-pricing problem with continuous review inventory control policy and batch arrival queuing approach, is presented. To best of our knowledge, (I) demand function is stochastic and price dependent; (II) due to the uncertainty in real-world situations, a fuzzy programming approach is applied. Therefore, the presented model with goal of maximizing total profit of system analyzes the price and order quantity decision variables. Since the proposed model belongs to NP-hard problems, Pareto-based approaches based on non-dominated ranking and sorting genetic algorithm are proposed and justified to solve the model. Several numerical illustrations are generated to demonstrate the model validity and algorithms performance. The results showed the applicability and robustness of the proposed soft-computing-based approaches to analyze the problem.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.606-608
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• 2003

경쟁적인 전력시장에서의 전력 가격은 전력에 대한 수요(Demand)와 공급(Supply)에 의한 시장원리에 의해 결정되기 때문에, 매 시각의 전력가격은 정해져 있지 않고 시장에 의해 결정된다. 이와 같이 전력가격이 가지는 가변성 및 불확실성(Volatility) 때문에 향후 전력 시장에 참여하는 사업자의 수입(Revenue) 및 수익 규모의 불확실성이 커지는 한편, 전력을 사용하는 소비자의 에너지비용도 그 불확실성이 매우 크게 증가하게 마련이다. 이러한 전력가격의 가변성(Volatility)과 불확실성(Uncertainty)이 대두됨에 따라, 외국의 경우, 가정용 부하와 같은 소규모 전력소비자를 제외한 대부분의 대규모 소비자(산업용, 상업용, 일반용 전력소비자)들은 전력가격이나 자신이 사용하고 있는 전력의 소비패턴과 같은 정보(Information)와 전략(Strategy)이 없는 경우, 예전에 비해 상당히 높은 전기요금을 지불해야 하는 상황에 처하게 되었다. 본 논문에서는 이러한 경쟁적 환경에서 직접부하제어자원을 활용하여 비용 및 위험을 관리하는 해외사례를 집중적으로 분석하고자 한다.

• Journal of the Semiconductor & Display Technology
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• v.9 no.4
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• pp.45-50
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• 2010

This paper explores a new approach for modeling of decision-making problems that involve uncertain, time-dependent and sequence-dependent processes which can be applied to semiconductor industry. In the proposed approach, which is based on probability theory, approximate sample paths are required to be specified by probability and statistic characteristics. Completely specified sample paths are seen to be elementary and fundamental outcomes of the related experiment. The proposed approach is suitable for modeling real processes more accurately. A case study is applied to a single item production planning problem with continuous and uncertain demand and the solution obtained by the approximate path specification method shows less computational efforts and practically desirable features. The application possibility and general plan of the proposed approach in semiconductor manufacturing process is also described in the paper.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.1
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• pp.141-150
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• 2014

Due to their accessibility and 24-hr availability, convenience stores are an integral part of daily lives. Because they sell a limited number of products and have small shelf space, shelf space allocation and inventory replenishment are important considerations for inventory management that critically affect profit. In this paper, we propose five solutions for the vendor-managed inventory problem of convenience stores that maximize profit while considering stock-out-based product substitutions. The performance of the proposed solutions is evaluated via simulation to reflect the demand uncertainty and marketing activity.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.36 no.3
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• pp.43-50
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• 2013

In this paper, the single-period inventory problem, what is called newsboy problem, has been revisited with two different conditions, uncertain supply and risk-averseness. Eeckhoudt et al. [5] investigated the effect of risk-averseness of a newsboy on the optimal order quantity in a stochastic demand setting. In contrary to Eeckhoudt et al. [5] this paper investigates the effect of risk-averseness in a stochastic supply setting. The findings from this investigation say that if ${\alpha}^*$ represents the optimal order quantity without risk-averseness then the risk-averse optimal order quantity can be greater than ${\alpha}^*$ and can be less than ${\alpha}^*$ as well.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.11
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• pp.453-462
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• 2006

This paper evaluates the reliability of KEPCO system using TRELSS, which is a probabilistic reliability evaluation program for large-scaled power system. In order to reflect the characteristic of KEPCO system, the sensitivity of reliability indices such as LOLP, EDLC, EENS and Energy Curtailment for variations of TRELSS parameter and input data was analyzed. Additionally, probabilistic reliability of KEPCO system reflecting sensitivity analysis results was systematically evaluated and simulated. Finally, maximum acceptable FOR of KEPCO system to satisfy reliability criterion, which meet in process of establishing the basic plan for long-term electricity supply and demand is suggested.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.598-599
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• 2007

The electricity supply industry for which high stability and quality of power are the primary aim of power company and the first order of business target. As the facilities of generations, transmissions and substations are increased every year, power system becomes more complex and hard to control. The complexity of the power system causes harmful influence on its security and power facilities. Moreover, difficulty of predicting weather condition in these days with its complexity increases the level of uncertainty of energy demand. Wide area online monitoring of power system offers lots of informations and solutions which clear the causes of insecurity in power system. In this paper, we presents the development of synchrophasor data measurement and transmission system using satellite network for power system online monitoring.

• Journal of the Korean Society of Safety
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• v.12 no.2
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• pp.70-79
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• 1997

This paper presents a study on the fuzzy linguistic variable based approach for safety assessment of human body in ELF electromagnetic field considering power system states. To cope with the demand in modern industry, the power system becomes larger in scale, higher in voltage. The advent of high voltage system has increased the relative importance of field effects. The analysis of ELF electromagnetic field based on Quasi-Static Method is introduced while the power system is included to model the expected and/or unexpected uncertainty caused by the load fluctuation and parameter changes. In order to analyze the power system, Monte Carlo simulation method and contingency analysis method are adopted in normal state and alert state, respectively. In the safety assessment of human body, the approach based on fuzzy linguistic variable is employed to overcome the shortcomings resulting from a crisp set concept. The suggested scheme is applied to a sample system(modified IEEE 14 bus system) to validate the usefulness.

• Earthquakes and Structures
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• v.10 no.3
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• pp.629-643
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• 2016

Among all the natural disasters, earthquakes are the most destructive calamities since they cause a plenty of injuries and economic losses leaving behind a series of signs of panic. The present study highlights the moment-curvature relationships for the structural elements such as beam and column elements and Non-Linear Static Pushover Analysis of RC frame structures since it is a very simplified procedure of non-linear static analysis. The highly popular model namely Mander's model and Kent and Park model are considered and then, seismic risk evaluation of RC building has been conducted using SAP 2000 version 17 treating uncertainty in strength as a parameter. From the obtained capacity and demand curves, the performance level of the structure has been defined. The seismic fragility curves were developed for the variations in the material strength and damage state threshold are calculated. Also the comparison of experimental and analytical results has been conducted.

• Journal of Contemporary Eastern Asia
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• v.21 no.1
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• pp.43-52
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• 2022

This study examines the impacts of a mandatory lockup ratio and lockup period, together with voluntary lockup, on the initial public offering (IPO) subscription rate in Malaysia. A sample of 390 IPOs launched from 2000 to 2016 was collected for analysis. The findings show that firms that adopt a lower lockup ratio and a shorter lockup period signal uncertainty about their prospects. Issuers would then show the tendency to underprice to increase investors' intention to subscribe to firms' IPO shares. This study concludes that as long as investors are aware of pertinent information about IPO firms, they should continue participating in the IPO market rather than behaving irrationally. Finally, policymakers could use the findings to improve the existing lockup provisions regulation.