• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.1
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• pp.37-44
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• 2002

This Paper suggests reasonable pricing mathod fur Reactive Power in Optimal Power Flow for the system analysis. Under restructuring, not only real power pricing but also reactive power pricing is important for the system analysis and operation. If people just focus on real power pricing, the Generators may no generate reactive power voluntarily, because the Generators may not recover the cost of the reactive power generation. So making a reasonable reactive power pricing is becoming more important than any other time. In this paper, the authors set a Proper Power factor and price the portion of the reactive power that exceeds the power factor using Interior Point Method. By applying this method, the System operator can use this strategy for the analysis of reactive power generation pricing and the Generator can get the motivation to generate reactive power. The author develops fully optimized fast Primal Dual Interior Point Method with sparsity technique and applies this method to Reliability Test System (RTS24) and KEPCO 674 bus system (684 buses. 1279 lines). It shows adaptability and usefulness.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.1089-1095
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• 2014

Innumerable microgrids would be operated independently by individual operators in a future smart grid. This kind of decentralized power system requires entirely different operation scheme in the actual power system and electricity market operation. Especially, frequency regulation is very important for successive energy trade in this multi-microgrid circumstance. This paper presents an optimal energy and reserve market participation strategy and operation strategy of energy storage system (ESS) by a microgrid operator (MGO). For definite evaluation of the proposed strategy, we postulate that the MGO should participate in the Power Exchange for Frequency Control (PXFC) market, which was devised by Maria Ilic and her coworkers and is suitable to the decentralized operation circumstances. In particular, optimal reserve capacity of the frequency control market and optimal market participation ratio of ESS between frequency control market and energy market are derived theoretically and evaluated by simulations utilizing Nordic Pool Elspot price data.

• Korean Journal of Organic Agriculture
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• v.30 no.4
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• pp.517-528
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• 2022

This study analyzed the factors influencing the demand for processed products of ugly agricultural products targeting 300 consumers. First, the awareness of the problem of the disposal of ugly agricultural products was very high at 72%. In other words, it can be seen that consumers are highly interested in environmental issues caused by the disposal of ugly agricultural products. Second, the experience of purchasing ugly agricultural products is high at 73%, which is proof that consumers are highly aware of and likely to purchase ugly agricultural products. Third, 77.6% of the respondents said they were willing to purchase processed ugly agricultural products. In other words, it was found that the intention to consume ugly agricultural products was sufficient. Finally, the conjoint analysis was applied to analyze the attribute value of ugly agricultural products. As a result of calculating the total utility of the optimal properties and optimal properties of the ugly fruit fermented, the total utility of the optimal properties was 0.778, the price was 0.481, the eco-friendly certification was 0.004, and the fruit syrup ratio was 0.294.

• Korean Journal of Organic Agriculture
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• v.29 no.4
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• pp.507-521
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• 2021

The livestock farmers are producing under uncertainties such as Foot-and-Mouth Disease (FMD) and Free Trade Agreement (FTA). The purpose of this study is to strengthen the management capabilities of Hanwoo farmers to prepare them for the uncertainties just mentioned. To this end, this study was conducted to find the optimal rearing period in order to reduce the feed cost, which accounts for the largest portion of the operation cost of Hanwoo. Using the universal lattice model, 41,139 of 289,000 Hanwoo slaughter data from 2010 to 2019 were used for the FMD period and 246,605 heads for the general period. The results show that the maximum cutoff price of Hanwoo steer is 6,394,457 won at the 4th week of 27 months of age in general period, where as 6,242,752 won at the 2nd week of 26 months of age in the FMD period. Therefore, it is judged that it will be helpful for Hanwoo farms to maximize their business profits by slaughtering one month and two weeks earlier in the FMD period than in the general period. In addition, Hanwoo farmers need to break away from the conventional rearing method and improve their management efficiency through a more flexible rearing method.

• Journal of Korean Society of Transportation
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• v.26 no.5
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• pp.101-115
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• 2008

This study reports UTIS(Urban Traffic Information System), which has been generalized in developed countries through brisk research and development and is being promoted for introduction by National Police Agency and Road Traffic Authority to reduce the astronomical amount of social expenses including traffic congestion expenses. Also this study investigates the proper charges for using by the preestimate of demand and contentment according to methods of payment after the service is introduced. The results of this study are as follows. First, demand forecast model is constructed by Binary Logit Model. Second, forecast models of using aspects of UTIS service according to methods of payment are established by Ordered Probit Model. Third, the proper charges for using of UTIS service according to methods of payment are presented to the supplier in the aspects of users. For this, preferences by using aspects and methods of payment are captured. And unit elasticity of coefficient of utilization is understood through responsiveness analysis according to methods of payment.

• Journal of Korean Society of Forest Science
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• v.83 no.3
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• pp.271-279
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• 1994

This paper descbibes a fuzzy multiobjective linear programming, which is a relatively new approach in forestry in solving forest management problems. At first, the fuzzy set theory is explained briefly and the fuzzy linear programming(FLP) and the fuzzy multiobjective linear programming(FMLP) are introduced conceptionally. With the information obtained from the study area in Thailand, a standard linear programming problem is formulated, and optimal solutions (present net worth) are calculated for four groups of timber price by this LP model, respectively. This LP model is reformulated to a fuzzy multiobjective linear programming model to accommodate uncertain timber values and with this FMLP model a compromise solution is attained. Optimal solutions of four objective functions for four timber price groups and the compromise solution are compared and discussed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11B
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• pp.700-708
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• 2007

This paper considers an incentive regulation in the telecommunications industry with respect to the sale of retail and access services. This regulation scheme induces the monopoly carrier who owns bottleneck facilities to adopt socially optimal outcomes when providing access and retail services. It is well known that upstream carriers can realize an integrated level of profit, without integration, by means of a two-part tariff. First, this paper introduces a framework for regulating an access and retail price combined with budget balancing. Second, this paper introduces two-part tariff (price discrimination) scheme for both access (upstream) and retail (downstream) services and discusses the resulting implications for incentive regulation when the regulator has incomplete information about cost functions. By imposing a self-selection mechanism, the regulator can induce firms to adopt socially optimal prices in both access and retail markets.

• Journal of KIISE:Information Networking
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• v.33 no.1
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• pp.103-112
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• 2006

Priority-based network service has been widely adopted for the Internet traffic management in the context of IETF differentiated services, and computing optimal prices for such priority-based service is the key topic in many pricing literature. While the equilibrium analysis has been commonly used to this end, many have criticized the validity of the underlying assumption of equilibrium analysis that user utility functions are precisely known. In this paper, we propose a solution for bridging the gap between the existing theoretical work on optimal pricing and the unavailability of precise user utility information in real networks. In the proposed method, the service provider obtains more and more accurate estimates of user utility functions from the initial imprecise knowledge by iteratively changing the price of service levels and observing the users' decisions under the changed price. Our contribution is two-fold. First, we have developed a general principle for estimating the user utility functions. Second, we have developed a novel method for setting the prices that can optimize the extraction of the knowledge about user utility functions. The extensive simulation results demonstrate the effectiveness of our method.

• Journal of Intelligence and Information Systems
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• v.25 no.2
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• pp.39-55
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• 2019

Recently banks and large financial institutions have introduced lots of Robo-Advisor products. Robo-Advisor is a Robot to produce the optimal asset allocation portfolio for investors by using the financial engineering algorithms without any human intervention. Since the first introduction in Wall Street in 2008, the market size has grown to 60 billion dollars and is expected to expand to 2,000 billion dollars by 2020. Since Robo-Advisor algorithms suggest asset allocation output to investors, mathematical or statistical asset allocation strategies are applied. Mean variance optimization model developed by Markowitz is the typical asset allocation model. The model is a simple but quite intuitive portfolio strategy. For example, assets are allocated in order to minimize the risk on the portfolio while maximizing the expected return on the portfolio using optimization techniques. Despite its theoretical background, both academics and practitioners find that the standard mean variance optimization portfolio is very sensitive to the expected returns calculated by past price data. Corner solutions are often found to be allocated only to a few assets. The Black-Litterman Optimization model overcomes these problems by choosing a neutral Capital Asset Pricing Model equilibrium point. Implied equilibrium returns of each asset are derived from equilibrium market portfolio through reverse optimization. The Black-Litterman model uses a Bayesian approach to combine the subjective views on the price forecast of one or more assets with implied equilibrium returns, resulting a new estimates of risk and expected returns. These new estimates can produce optimal portfolio by the well-known Markowitz mean-variance optimization algorithm. If the investor does not have any views on his asset classes, the Black-Litterman optimization model produce the same portfolio as the market portfolio. What if the subjective views are incorrect? A survey on reports of stocks performance recommended by securities analysts show very poor results. Therefore the incorrect views combined with implied equilibrium returns may produce very poor portfolio output to the Black-Litterman model users. This paper suggests an objective investor views model based on Support Vector Machines(SVM), which have showed good performance results in stock price forecasting. SVM is a discriminative classifier defined by a separating hyper plane. The linear, radial basis and polynomial kernel functions are used to learn the hyper planes. Input variables for the SVM are returns, standard deviations, Stochastics %K and price parity degree for each asset class. SVM output returns expected stock price movements and their probabilities, which are used as input variables in the intelligent views model. The stock price movements are categorized by three phases; down, neutral and up. The expected stock returns make P matrix and their probability results are used in Q matrix. Implied equilibrium returns vector is combined with the intelligent views matrix, resulting the Black-Litterman optimal portfolio. For comparisons, Markowitz mean-variance optimization model and risk parity model are used. The value weighted market portfolio and equal weighted market portfolio are used as benchmark indexes. We collect the 8 KOSPI 200 sector indexes from January 2008 to December 2018 including 132 monthly index values. Training period is from 2008 to 2015 and testing period is from 2016 to 2018. Our suggested intelligent view model combined with implied equilibrium returns produced the optimal Black-Litterman portfolio. The out of sample period portfolio showed better performance compared with the well-known Markowitz mean-variance optimization portfolio, risk parity portfolio and market portfolio. The total return from 3 year-period Black-Litterman portfolio records 6.4%, which is the highest value. The maximum draw down is -20.8%, which is also the lowest value. Sharpe Ratio shows the highest value, 0.17. It measures the return to risk ratio. Overall, our suggested view model shows the possibility of replacing subjective analysts's views with objective view model for practitioners to apply the Robo-Advisor asset allocation algorithms in the real trading fields.

• Korean Journal of Agricultural Science
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• v.49 no.2
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• pp.203-214
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• 2022

A model is developed for estimating optimal cultivation areas for apples to maximize the total profit of apple farming by region, focusing on Gyeongsangbuk-do, Chungchungbuk-do, Gyeongsangnam-do, and Jeonllabuk-do in Korea. Comparing the current cultivation areas to the optimal areas according to the model estimation during the period 1999 - 2019, the former has exceeded the latter since 2015 in all regions except for Jeonllabuk-do. This result stems from a lack of the regulation of production quantity among apple producers' regional organizations. Accordingly, the decreasing rate of the market price was greater than the increasing rate of the production quantity, and the total profit of apple farming has fallen in conjunction with increasing agricultural wage rates. Therefore, in order to reverse the current decreasing trend in the profits of apple farming, it is necessary to regulate nationwide apple cultivation areas through regional producers' associations. Ex-ante forecasting for 2019 posits the following regional optimal cultivation areas for maximizing the total income from apple farming. The Gyeongbuk apple producers' association needs to reduce its current cultivation area by 1,089 ha and to maintain 18,373 ha. In the Chungbuk region, current cultivated area should be reduced by 1,027 ha to maintain 2,722 ha, and in the Gyeongnam region, the current cultivated area should be reduced by 582 ha to maintain 2,730 ha. In contrast, the Jeonbuk region needs to increase its current cultivation area by 174 ha and to maintain at a level of 2,872 ha.