• Journal of Korean Institute of Industrial Engineers
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• v.38 no.2
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• pp.116-124
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• 2012

This paper concerns a joint replenishment problem for a single buyer who sells multiple types of items to end-customers. The buyer periodically replenishes the inventory of each item to a preset order-up-to-level to satisfy the end customers' demands, which may be non-stationary. A joint replenishment policy characterized by variable order-up-to-levels is proposed for the buyer who wishes to minimize the expected cost of operating the retail system. The proposed policy starts each period by calculating the expected cost of ordering and not ordering action based on the information of the current inventory position and forecasted demand for the upcoming period. It then takes advantage of an integer programming model to get a cost effective joint replenishment plan. Computer experiment was performed to test efficiency of the proposed policy. When compared with the most efficient policy currently available, our policy showed a considerable cost savings especially for the problems having non-stationary demands.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.4
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• pp.451-458
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• 2018

The coast of Incheon reaches Incheon itself, Gimpo, Siheung, and Ansan of Gyunggi-do. Because this area has been seriously polluted, the Ministry of Oceans and Fisheries has established the Incheon Special Area Management Plan (SAMP) to preserve sea water quality as a marine environment asset. However, there is concern that actions taken in this area may change the surrounding marine ecology, being effected by farms, via a river that flows from waste lands, abandoned fishing activities and fishing nets, etc. Given this background, this study estimates the value of SAMP sea water quality using a choice experiment (CE). A CE survey of 1,000 households was undertaken, investigating trade-offs involving price and four attributes for selecting a preferred alternative to obtain a marginal willingness to pay (MWTP) estimate for each attribute. The estimation results showed that MWTP for a 1 %p improvement in sea water quality, the diversity of fauna species, the diversity of flora species, and a 1 %p reduction in marine litter as a result of conserving Incheon coastal sea water quality are estimated to be KRW 75, 135, 309 and 72 per household per year, respectively. All estimation results were statistically significant at the 1 % level. These findings can provide policy makers with useful information for evaluating and planning marine environmental management policies.

• Journal of Navigation and Port Research
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• v.33 no.7
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• pp.477-482
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• 2009

In this paper the order picking problem in warehouses is considered, a topic which has received considerable attention from the international academic body in recent years. The order picking problem deals with the retrieval of order items from prespecified locations in the warehouse, and its objective is usually the minimization of travel time or travel distance. Hence, a well-thought order picking policy in combination with an appropriate storage policy will enhance warehouse efficiency and reduce operational costs. This paper starts with a literature overview summarizing approaches to routing order pickers, assigning stock-keeping units to pick locations and designing warehouse layouts. Since the layout design might affect both storage and routing policies, the three factors are interdependent with respect to order picking performance. To test these interdependencies, a simulation experiment was set up, involving two types of warehouse layout, four types of storage policy, five well-known heuristics and five sizes of order picking list. Our results illustrate that from the point of view of order picking distance minimization it is recommended to equip the warehouse with a third cross aisle, although this comes at the cost of a certain space loss. Additionally, we propose a set of most appropriate matches between order picking heuristics and storage policies. Finally, we give some directions for further research and recommend an integrated approach involving all factors that affect warehouse efficiency.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.4
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• pp.39-46
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• 2011

This study is conducted to examine the optimal integrated security policy based on network in case of attacks by implementing unique security policies of various network security equipments as an algorithm within one system. To this end, the policies conduct the experiment to implement the optimal security system through the process of mutually integrating the unique defense policy of Firewall, VPN(Virtual Private Network), IDS(Intrusion Detection System), and IPS(Intrusion Prevention System). In addition, this study is meaningful in that it designs integrated mechanism for rapid detection of system load caused by establishment of the security policy and rapid and efficient defense and secures basic network infrastructure implementation.

• KDI Journal of Economic Policy
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• v.45 no.2
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• pp.1-20
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• 2023

Carbon pricing is in the spotlight as an economically efficient policy to limit global warming and reduce greenhouse gas emissions. We examine how policymakers can improve social acceptance of a carbon tax, which is the main obstacle in implementing the policy. We conduct a survey experiment to analyze this topic and adopt two different interventions focusing on the use of revenue from a carbon tax and types of information to be provided. Regarding revenue use, we consider 1) tax reductions, 2) lump-sum transfers, and 3) green project investments. For information types, we focus on 1) the economic value of a carbon tax, and 2) the environmental value of a carbon tax. We find that lump-sum transfers have negative impacts on social acceptance of a carbon tax. For those who perceive climate change as a serious issue, moreover, both lump-sum transfers and tax reductions have negative impacts on acceptability. Regardless of the type of information provided, on the other hand, the social acceptance of a carbon tax is increased after the provision of information. Furthermore, the impact of information provision on the social acceptance interacts with the revenue use impacts. When the revenue use and the type of information are consistent with the aim of the policy, the effects of these strategies can be amplified.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.5
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• pp.1-6
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• 2009

MANET(Mobile Ad-hoc NETwork), a network characterized that its moving nodes freely constructs Network topology, has other different characteristics. Because Policy based Network Management in MANET guarantees QoS between nodes, it is essential in applied areas like VANET which targets safety and convenience. In this paper, we use COPS-PR which is appropriate Policy Exchange Protocol for MANET, and implement DiffServ-based QoS in the real networks and experiment its capability.

• Journal of Information Technology Services
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• v.14 no.1
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• pp.85-98
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• 2015

As we enter the technology and knowledge-intensive era, standardization has become a key element to increase the sustainability of companies. However, standardization activities have not been proceeded well due to lack of relevant information, financial and human resources and complexity of the authentication process. Thus, in this paper, we analyze the effect of understanding the internal and external standard trends surrounding companies and recognizing the difficulties of standardization process on the needs of standard/standardization education. We suggest an experiment model and associated variables for analysis based on the previous studies. The analysis results from 1,000 companies that belong to telecommunication industry and electrical and electronics industry showed positive relationships among these three variables. Furthermore, we propose major policy directions for increasing standardization effect.

• IE interfaces
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• v.24 no.4
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• pp.396-407
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• 2011

We develop a cash management model in which firms face randomly occurred investment projects and retrieve investments upon the maturity of these projects. Using the Markov Decision Problem approach, we examine a control policy which dynamically adjusts the cash balance under the discounted cost criterion. The existence of an optimal policy is shown under some conditions. The optimal solution procedure is developed to find the optimal points and the optimal sizes for adjusting the cash balance. In numerical experiment, we investigate important structural properties of the optimal cash management policy.

• Journal of Korean Institute of Industrial Engineers
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• v.30 no.3
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• pp.241-249
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• 2004

By committing to a long-term replenishment contract, suppliers can mitigate the pressure to find new customers and afford to charge a discounted price to buyers seeking to lower their purchasing costs. In this paper, we develop an analytical model from buyer's perspective for the contracting process to investigate the buyer-supplier interactions. Based on the developed model, we propose an algorithm to derive optimal strategy for the contract. We consider a system with a single buyer and a supplier in a situation where the buyer's inventory is controlled by (R, S) policy under VMI setting. According to the contract, the supplier should replenish the buyer's inventory up to a fixed level every R times during a specified period. The buyer purchases any deficient amount from a spot market at a higher price. We show by computational experiment that our proposed algorithm finds the global optimum solution.

• Korean System Dynamics Review
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• v.5 no.1
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• pp.35-47
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• 2004

Analyzers adopt a variety of techniques in analyzing public policy. Based on the results of exploration, they explain problems and suggest prescriptions such as policy alternatives. By doing so, however, they have different degree of confidence in their own results according to what techniques they adopt. This study explores whether system dynamics apporach gives analyzers more confidence on their own simulation results than other approaches do. This study designed an experiment. Three research teams are organized. Each of them applies different analytic techniques on the same policy issue, i.e., introduction of transportation tax. It flnds that researchers using S,D. simulation technique are most confident on what they predict, while researchers adopting survey techniques show moderate degree of confidence on their results. Researchers using regression are least confident.