• Journal of the Korea Society for Simulation
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• v.15 no.3
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• pp.79-86
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• 2006

This paper proposes a new protocol to enhance the routing performance and applies our proposal to AODV (Ad hoc On-demand Distance Vector routing) protocol, which is a typical on-demand routing protocol in MANET. In general, when a route repair procedure is performed due to the transfer or failure of a node, the source node re-initiate a route discovery procedure in most routing protocols of MANET. This causes to increase the control traffic overhead largely and degrade the routing performance. The main idea of our study is to provide a methodology that can minimize the control traffic overhead and enhance the performance by initiating a route repair procedure at destination node and utilizing the previous routing information maximumly. To evaluate the performance of the our mechanism, we have performed a series of simulations. The simulations include comparisons with AODV and AODV with local repair. The simulations have been executed under simulation environments taking into account mobility speed and network site. The simulation results show that our proposal overall outperforms the existing protocols.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2220-2226
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• 2018

Electric vehicles (EVs) are significant resources for demand response (DR). Thus, it is essential for EV aggregators to quantitatively evaluate their capability for DR. In this paper, a concept of dynamic equivalent battery (DEB) is proposed as a metric for evaluating the DR performance using EVs. The DEB is the available virtual battery for DR. The capacity of DEB is determined from stochastic calculation while satisfying the charging requirements of each EV, and it varies also with time. Further, a new indicator based on the DEB and time-varying electricity prices, named as value of DEB (VoDEB), is introduced to quantify the value of DEB coupled with the electricity prices. The effectiveness of the DEB and the VoDEB as metrics for the DR performance of EVs is verified with the simulations, where the difference of charging cost reduction between direct charging and optimized bidding methods is used to express the DR performance. The simulation results show that the proposed metrics accord well with the DR performance of an EV fleet. Thus, an EV aggregator may utilize the proposed concepts of DEB and VoDEB for designing an incentive scheme to EV users, who participate in a DR program.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.61
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• pp.213-245
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• 2014

This study has significance in examining the formation requirements and notes for concluding the guarantee contract of minimizing interests and conflicts with the concerned parties by examining issues related to the legal relation and demand payment in the concerned parties and by figuring out the provisions of conformity related to the requirements for demand payment pertinent to the documentary provision in relation to characteristics of demand guarantee. What the concerned parties of using demand guarantee grasp the requirements for demand payment of being compliant with the essence and the guarantee condition of the demand guarantee will lead to possibly preventing a dispute caused by disagreement and being secured the fulfillment of underlying contract. To fulfill a underlying contract that is the objective of issuing the demand guarantee, an effort is needed that minimizes a contract-based risk and a cost by being fully aware of a relevant rule that will be recorded in the terms of payment in the demand guarantee, by reflecting the interests between the concerned parties, and by discussing the payment terms.

• IE interfaces
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• v.24 no.4
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• pp.351-361
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• 2011

Forecasting of electricity demand have difficulty in adapting to abrupt weather changes along with a radical shift in major regional and global climates. This has lead to increasing attention to research on the immediate and accurate forecasting model. Technically, this implies that a model requires only a few input variables all of which are easily obtainable, and its predictive performance is comparable with other competing models. To meet the ends, this paper presents an energy demand forecasting model that uses the variable selection or extraction methods of data mining to select only relevant input variables, and employs support vector regression method for accurate prediction. Also, it proposes a novel performance measure for time-series prediction, shift index, followed by description on preprocessing procedure. A comparative evaluation of the proposed method with other representative data mining models such as an auto-regression model, an artificial neural network model, an ordinary support vector regression model was carried out for obtaining the forecast of monthly electricity demand from 2000 to 2008 based on data provided by Korea Energy Economics Institute. Among the models tested, the proposed method was shown promising results than others.

• Journal of Information Technology Applications and Management
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• v.30 no.3
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• pp.1-13
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• 2023

Demand forecasting is a crucial task for an online retail where has to manage daily fresh foods effectively. Failing in forecasting results loss of profitability because of incompetent inventory management. This study investigated the optimal performance of different forecasting models for a very short shelf-life product. Demand data of 13 perishable items with aging of 210 days were used for analysis. Our comparison results of four methods: Trivial Identity, Seasonal Naïve, Feed-Forward and Autoregressive Recurrent Neural Networks (DeepAR) reveals that DeepAR outperforms with the lowest MAPE. This study also suggests the managerial implications by employing coefficient of variation (CV) as demand variation indicators. Three classes: Low, Medium and High variation are introduced for classify 13 products into groups. Our analysis found that DeepAR is suitable for medium and high variations, while the low group can use any methods. With this approach, the case can gain benefit of better fill-rate performance.

• Steel and Composite Structures
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• v.33 no.5
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• pp.641-652
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• 2019

This paper investigates the effect of aftershocks on the seismic performance of self-centering (SC) prestressed concrete frames using the probabilistic seismic demand analysis methodology. For this purpose, a 4-story SC concrete frame and a conventional reinforced concrete (RC) frame are designed and numerically analyzed through nonlinear dynamic analyses based on a set of as-recorded mainshock-aftershock seismic sequences. The peak and residual story drifts are selected as the demand parameters. The probabilistic seismic demand models of the SC and RC frames are compared, and the SC frame is found to have less dispersion of peak and residual story drifts. The results of drift demand hazard analyses reveal that the SC frame experiences lower peak story drift hazards and significantly reduced residual story drift hazards than the RC frame when subjected to the mainshocks only or the mainshock-aftershock sequences, which demonstrates the advantages of the SC frame over the RC frame. For both the SC and RC frames, the influence of as-recorded aftershocks on the drift demand hazards is small. It is shown that artificial aftershocks can produce notably increased drift demand hazards of the RC frame, while the incremental effect of artificial aftershocks on the drift demand hazards of the SC frame is much smaller. It is also found that aftershock polarity does not influence the drift demand hazards of both the SC and RC frames.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.4
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• pp.343-351
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• 2014

Washing machines designed to clean laundry have been more widely used at home as they reduce household labor and boost the quality of life. Technological advances and better standards of life increase demand for laundry washing performance. Energy efficiency regulations and consumer demand for the larger trend, washing machine makers should be done in performance studies to reduce power, and water consumption and the load on power transmission devices. In this study, performance of a fully automatic washing machine with unconstrained transmission is analyzed through experiment and CFD simulation. It is found that the interaction between laundry and transmission change the washing behavior and affect washing performance with regard to the degree of freedom. The results obtained in this study can be used in developing new washing machine transmissions and make them more robust.

• The Research Journal of the Costume Culture
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• v.12 no.4
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• pp.547-565
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• 2004

The purpose of this study was to evaluate the level of SCM activities and the logistics performance by SCM of the three company types in fashion industry· fabric suppliers, apparel manufacturers, and retailers. The level of SCM activities was estimated through the examination of seven factors: commitment and leadership of a top management, flexibility of management, understanding of demand characteristics, integrated management organization, information system, cooperative partnership and communication and exchange of opinion. The logistics performance was measured by improvement in customer service(on time delivery ratio of products, returning rate, treat ratio for A/S, order fill rate, substitute providing capability for being out of stock) and delivery cost reduction. Through questionnaire survey, a total of 214 data for 108 companies of three company types were collected: 46 for 40 fabric suppliers, 123 for 64 apparel manufacturers and 45 for 4 retailers. The analysis of SCM activity levels showed that fabric suppliers had higher degrees in the factor of understanding of demand characteristics, and apparel manufacturers had higher degrees in the factor of information systems. For retailers, the factor of communication and exchange of opinion represented higher degrees. The study on relationship between the SCM activity levels and logistics performance showed that the SCM activity factor of understanding of demand characteristics greatly improved a substitute providing capability for being out of stock in fabric suppliers, and information system improved a substitute providing capability for being out of stock, on time delivery ratio of products and order fill rate in apparel manufacturers. In retailers, the SCM activity factor of understanding of demand characteristics decreased returning rate highly and improved on time delivery ratio of products. The study results showed that SCM activities in fashion industry brought more improvement in customer service levels rather than in delivery cost reduction.

• Journal of Information Technology Services
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• v.12 no.4
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• pp.349-367
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• 2013

In MANET, the AODV routing protocol with on-demand method has a problem in large control packet overhead. In order to improve this, we first need a comprehensive analysis of correlation between performance metrics and factors affecting the performance of AODV. Selected parameters based on this analysis make it enable to be a more accurate and fair performance analysis, as well as to reduce the time and effort when constructing a scenario for performance analysis. In this paper, various scenarios are configured to apply AODV by varying the values of factors affecting the performance with network simulator QualNet 5.0, and then the results are analysed using performance metrics proposed by IETF MANET working group. This paper also founds a correlation between performance metrics and factors affecting the performance for AODV routing protocol, choosing the values of factors that represent many of the most maximum and minimum values of each performance metrics, and proposes optimal simulation parameters for a more accurate performance evaluation of routing protocols with minimal scenario in experiments. Next, performance comparison of AODV, DSR and DYMO routing protocols based on the proposed simulation parameters is shown which provides a comparative analysis on the performance of on-demand routing protocols. Results of this paper could be very useful for the researcher or service provider who wants to find nice simulation environment or select a proper routing protocol.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.213-217
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• 2003

An Ad-Hoc networks is a set of wireless mobile host which forms temporary networks without any concentrated controls or any helps of standard support services. Mobile host' routers are operated by their mobile hosts without fixed routers, therefore, the original routing protocol algorithm are not effective. There are two major Protocols in Ad-Hoc Network. A Table-Driven algorithm and an On-Demand, but the latter is presented more effective. We try to compare and analyze the performances of each protocol's host in this thesis.