• The Journal of Information Systems
• /
• v.21 no.3
• /
• pp.99-116
• /
• 2012

As a way to allocate lots of orders to many participants for vehicle allocation problem, this study has used an agent negotiation based reverse auction model. This agent negotiation provides coordination functions allowing all participants to make a profit, and accomplishing Pareto optimum solution from the viewpoint of a whole trucking cargo transportation network. In order to build a strategic cooperation relationship based on information sharing, this agent negotiation provides a coordination mechanism in which all the participants including consignors, brokerage firms, and car owners are able to attain their own profits, and also that ensure a competitive market. This study has tried to prove that the result of an agent-based negotiation is the Pareto optimal solution under the present market environment. We established a mathematical formulation for a comparison with the Integer Programming model, and analysing e-Marketplace, structure of shipping expenses and brokerage system in the trucking cargo transportation industry.

• Proceedings of the KIEE Conference
• /
• 1991.07a
• /
• pp.411-416
• /
• 1991

Operation simulation is a key factor to evaluate investment and operation in a power utility. Probabilistic production simulation is of major concern. With pumped-storage plant, production simulation is not an easy task, because its economy should fully be exploited. In addition, usual operation interval is a week rather than a day. Most existing models are based on approximate production simulation such as adopting simple priority orders of generations. This study is based on the more elaborate model developed by authors. Further, a policy of weekly coordination is established based on the Maximum Principle. Chronological load curve instead of usual load duration curve is used and the accuracy in simulation is enhahced. Resulting economics are compared. Deviation between these two toad curve is shown.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.8
• /
• pp.1485-1491
• /
• 2011

This paper deals with the technical problems for the protection devices, by simulating test facilities of protection coordination for Photovoltaic systems. In order to analyze the operation characteristics for the protection devices in the case that the Photovoltaic systems with bi-directional power supply are located in the feeder, this paper proposes the test facilities composed of model distribution system, protection device and model Photovoltaic systems. By performing the simulation for operation characteristics for the protection devices based on the test facilities, this paper presents the malfunction mechanism for the protection devices. The test results show that this paper is practical and effective for the technical guideline for the Photovoltaic systems.

• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.5
• /
• pp.413-418
• /
• 2012

This paper presents a multi-robot path planner for environment exploration and monitoring. Robotics systems are being widely used as data measurement tools, especially in dangerous environment. For large scale environment monitoring, multiple robots are required in order to save time. The path planner should not only consider the collision avoidance but efficient coordination of robots for optimal measurements. Nonlinear spring force based planning algorithm is integrated with the spatial gradient following path planner. Perturbation/Correlation based estimation of spatial gradient is applied. An algorithm of tuning the stiffness for robot coordination is presented. The performance of the proposed algorithm is discussed with simulation results.

• Proceedings of the KIEE Conference
• /
• 1996.07b
• /
• pp.771-773
• /
• 1996

This paper reports the protection coordination program, INPROSET for the industrial power system to determine the optimal TAP and Time-Dial of OCRs. INPROSET performs two stages process and the first stage starts form the highest level and depending on its results, the second stage achieves the higher relay operating time. The developed system proved effective through the tests on the real systems.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.11
• /
• pp.5264-5281
• /
• 2017

Multihop relay-based cellular networks are attracting much interest because of their throughput enhancement, coverage extension, and low infrastructure cost. In these networks, relay stations (RSs) between a base station (BS) and mobile stations (MSs) drastically increase the overall spectral efficiency, with improved channel quality for MSs located at the cell edge or in shadow areas, and enhanced throughput of MSs in hot spots. These relay-based networks require an advanced radio resource management scheme because the optimal amount of radio resource for a BS-to-RS link should be allocated according to the MS channel quality and distribution, considering the interference among RSs and neighbor BSs. In this paper, we propose optimal resource planning algorithms that maximize the overall utility of relay-based networks under a proportional fair scheduling policy. In the first phase, we determine an optimal scheduling policy for distributing BS-to-RS link resources to RSs. In the second phase, we determine the optimal amount of the BS-to-RS link resources using the results of the first phase. The proposed algorithms efficiently calculate the optimal amount of resource without exhaustive searches, and their accuracy is verified by comparison with simulation results, in which the algorithms show a perfect match with simulations.

• Industrial Engineering and Management Systems
• /
• v.13 no.2
• /
• pp.129-147
• /
• 2014

This study proposes an optimal operational policy for a green supply chain (GSC) where a retailer pays an incentive for collection of used products from customers and determines the optimal order quantity of a single product under uncertainty in product demand. A manufacturer produces the optimal order quantity of product using recyclable parts with acceptable quality levels and covers a part of the retailer's incentive from the recycled parts. Here, two scenarios for the product demand are assumed as: the distribution of product demand is known, and only both mean and variance are known. This paper develops mathematical models to find how order quantity, collection incentive of used products and lower limit of quality level for recycling affect the expected profits of each member and the whole supply chain under both a decentralized GSC (DGSC) and an integrated GSC (IGSC). The analysis numerically compares the results under DGSC with those under IGSC for each scenario of product demand. Also, the effect of the quality of the recyclable parts on the optimal decisions is shown. Moreover, supply chain coordination to shift the optimal decisions of IGSC is discussed based on: I) profit ratio, II) Nash bargaining solution, and III) Combination of (I) and (II).

• Journal of the Korean Operations Research and Management Science Society
• /
• v.25 no.3
• /
• pp.49-64
• /
• 2000

A vendor supplies a product to a sole/major buyer on a lot-for-lot basis under deterministic inventory control conditions. The basic premise is that the setup cost reduction technologies are available to both the buyer and the vendor, and that the vendor's inventory and setup reduction investment costs differ from the buyer's. Therefore, an individually designed ordering and setup cost reduction policy will likely cause mismatches between the vendor's and the buyer's optimal cycle times. For this situation, we show that a joint optimal setup cost reduction and ordering policy, together with an appropriate side payment(quantity discount or premium price) schedule, can be designed in a spirit in a spirit of coordination to eliminate mismatches in individual optimal cycle times.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.12
• /
• pp.4389-4410
• /
• 2014

Network coding is a promising technology that increases system throughput by reducing the number of packet transmissions from the source node to the destination node in a saturated traffic scenario. Nevertheless, some packets can suffer from end-to-end delay, because of a queuing delay in an intermediate node waiting for other packets to be encoded with exclusive or (XOR). In this paper, we analyze the delay according to packet arrival rate and propose two network coding schemes, iXOR (Intelligent XOR) and oXOR (Optimal XOR) with Markov Decision Process (MDP). They reduce the average delay, even under an unsaturated traffic load, through the Holding-${\chi}$ strategy. In particular, we are interested in the unsaturated network scenario. The unsaturated network is more practical because, in a real wireless network, nodes do not always have packets waiting to be sent. Through analysis and extensive simulations, we show that iXOR and oXOR are better than the Distributed Coordination Function (DCF) without XOR (the general forwarding scheme) and XOR with DCF with respect to average delay as well as delivery ratio.

• 전기의세계
• /
• v.21 no.1
• /
• pp.13-16
• /
• 1972

Dynamic Programming is regarded as a very powerful tool for solving nonlinear optimization problem subject to a number of constraints of state and control variables, but has definite disadvantages that it requires much more computing time and consumes much more memory spaces than other technigues. In order to eliminate the above-mentioned demerits, this paper suggests a news technique called Multiple Dynamic Programming. The underlying principles are based on the concept of multiple passes that, instead of forming fin lattices in time-state plane as adopted in the conventional Dynamic Programming, the Multiple Dynamic Programming constitutes, at the first pass, coarse lattices in the feasible domain of time-state plane and determines the optimal state trajectory by the usual method of Dynamic Programming, and at the second pass again constitutes finer lattices in the narrower domain surrounded by both the upperand lower edges next to the lattice edges through which the first pass optimal trajectory passes and determines the more accurate optimal trajectory of state, and then at the third pass repeats the same processes, and so on. The suggested technique insures remarkable curtailment in amounts of computer memory spaces and conputing time, and its applicability has been demonstrated by a case study on the hydro-thermal power coordination in Korean power system.