• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.4
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• pp.16-22
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• 2019

After Dantzig and Rasmer introduced Vehicle Routing Problem in 1959, this field has been studied with numerous approaches so far. Classical Vehicle Routing Problem can be described as a problem of multiple number of homogeneous vehicles sharing a same starting node and having their own routes to meet the needs of demand nodes. After satisfying all the needs, they go back to the starting node. In order to apply the real world problem, this problem had been developed with additional constraints and pick up & delivery model is one of them. To enhance the effectiveness of pick up & delivery, hub became a popular concept, which often helps reducing the overall cost and improving the quality of service. Lots of studies have suggested heuristic methods to realize this problem because it often becomes a NP-hard problem. However, because of this characteristic, there are not many studies solving this problem optimally. If the problem can be solved in polynomial time, optimal solution is the best option. Therefore, this study proposes a new mathematical model to solve this problem optimally, verified by a real world problem. The main improvements of this study compared to real world case are firstly, make drivers visit every nodes once except hub, secondly, make drivers visit every nodes at the right time, and thirdly, make drivers start and end their journey at their own homes.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.6
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• pp.9-16
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• 2010

For improving social safety, It is important to build Web DB of criminal prevention and open to the public. It could be help to mitigate social damage of crimes and accidents. In this study, the main goal is to analyze and apply the applicable contents from user demands studies and case studies for a domestic life safety Web DB. For this study 31 cases of international life safety Web DB were collected and analyzed. Customer participation style of Web service was reviewed. And demand survey for crime weakness group like students, and young women was examined. As a results people needed to know the un-safety area in their usual life and their ways; school to home, work to home. While creating the Web DB for domestic life safety, user content according to different economic status and publicity for Web DB proved to be important factors.

• Journal of Arbitration Studies
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• v.25 no.1
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• pp.65-86
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• 2015

Under current international investment law clear criteria to determine standards of indirect expropriation are absent. Arbitral tribunals determine on a case-by-case whether an indirect expropriation has occurred by conducting a fact-based inquiry. However, three common determination standards can be inferred by analyzing prior arbitration cases. The appropriate analytical framework that can be applied to determine whether a state's measure constitutes an indirect expropriation is as follows. i) the degree of economic invasion of the state's action into the foreign investor's property rights and durability of the period, ii) interference with the foreign investor's distinct and reasonable investment-backed expectations, and iii) the nature, purpose and character of the state's measure. Therefore, it is necessary to fully acknowledge and to utilize strategically this determination standard. However, derived standards cannot be applied to all disputes en masse. So, it is desirable to exclude ambiguity and to clearly define the determination standard of indirect expropriation in investment agreements, since arbitral tribunals can apply different determination standards on a case-by-case basis. And, based on the discussions until now, more developed standards and direction in response to demand should be established through consistent analysis and review of precedents related to indirect expropriation. Lastly, This study is expected to be a useful guideline to prepare a necessary countermeasure to prevent dispute related to indirect expropriation beforehand or in case of dispute occurrence.

• International Commerce and Information Review
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• v.10 no.1
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• pp.395-414
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• 2008

The objective of this study is to introduce the concepts and theories of conditional heteroscedastic volatility models and the news impact curves and apply them to the Korea inbound tourism market. Three volatility models were introduced and used to estimate the conditional volatility of monthly arrivals of inbound tourists into Korea and news impact curves according to the three models. Results of this study are as follows. As the proportion of American tourists occupied a large amount of Korea inbound tourism market, the markets' forecasting is very important. The news impact curves which used EGARCH model (1,1) and TGARCH model(1,1), with data on these tourists to Korea showed an asymmetry effect of volatility. It was common that bad news means that it was estimated more sensitively than good news. From these results, we will notice that American tourists who visited Korea only for tourism are affected by good news. The result suggests that the Korea government and tourism industry should pay more attention to changes in the tourism environment following bad news because conditional volatility increases more when a negative shock occurs than when a positive shock occurs.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.225-228
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• 2017

In this paper, we propose a methodology to deal with the IOT system gradually as the use of effective systems such as electronic devices, healthcare, smart cars, smart home, remote meter reading and telemedicine closely related to our real life in the IOT system An IOT integrated account solution is needed as a way to address these needs as the demand grows for the need to identify and manage how users access and use the system for what period of time and at what point in time. We propose the communication algorithms for endpoint system, IOT system management rights policy, user information, and how to apply them to IOT system smart car and smart home on each object internet.

• ETRI Journal
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• v.35 no.4
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• pp.687-696
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• 2013

The development of proxy caching is essential in the area of video-on-demand (VoD) to meet users' expectations. VoD requires high bandwidth and creates high traffic due to the nature of media. Many researchers have developed proxy caching models to reduce bandwidth consumption and traffic. Proxy caching keeps part of a media object to meet the viewing expectations of users without delay and provides interactive playback. If the caching is done continuously, the entire cache space will be exhausted at one stage. Hence, the proxy server must apply cache replacement policies to replace existing objects and allocate the cache space for the incoming objects. Researchers have developed many cache replacement policies by considering several parameters, such as recency, access frequency, cost of retrieval, and size of the object. In this paper, the Weighted-Rank Cache replacement Policy (WRCP) is proposed. This policy uses such parameters as access frequency, aging, and mean access gap ratio and such functions as size and cost of retrieval. The WRCP applies our previously developed proxy caching model, Hot-Point Proxy, at four levels of replacement, depending on the cache requirement. Simulation results show that the WRCP outperforms our earlier model, the Dual Cache Replacement Policy.

• Journal of Korean Institute of Industrial Engineers
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• v.32 no.1
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• pp.61-73
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• 2006

This paper deals with traveling salesman problem(TSP) with the stochastic travel time. Practically, the travel time between demand points changes according to day and time zone because of traffic interference and jam. Since the almost pervious studies focus on TSP with the deterministic travel time, it is difficult to apply those results to logistics problem directly. But many logistics problems are strongly related with stochastic situation such as stochastic travel time. We need to develop the efficient solution method for the TSP with stochastic travel time. From the previous researches, we know that Q-learning technique gives us to deal with stochastic environment and neural network also enables us to calculate the Q-value of Q-learning algorithm. In this paper, we suggest an algorithm for TSP with the stochastic travel time integrating Q-learning and neural network. And we evaluate the validity of the algorithm through computational experiments. From the simulation results, we conclude that a new route obtained from the suggested algorithm gives relatively more reliable travel time in the logistics situation with stochastic travel time.

• Journal of Mechanical Science and Technology
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• v.16 no.12
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• pp.1633-1642
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• 2002

Uninterrupted power supply has become indispensable during the maintenance task of active electric power lines as a result of today's highly information-oriented society and increasing demand of electric utilities. The maintenance task has the risk of electric shock and the danger of falling from high place. Therefore it is necessary to realize an autonomous robot system using electro-hydraulic manipulator because hydraulic manipulators have the advantage of electric insulation. Meanwhile it is relatively difficult to realize autonomous assembly tasks particularly in the case of manipulating flexible objects such as electric lines. In this report, a discrete event control system is introduced for automatic assembly task of electric lines into sleeves as one of the typical task of active electric power lines. In the implementation of a discrete event control system, LVQNN (linear vector quantization neural network) is applied to the insertion task of electric lines to sleeves. In order to apply these proposed control system to the unknown environment, virtual learning data for LVQNN is generated by fuzzy inference. By the experimental results of two types of electric lines and sleeves, these proposed discrete event control and neural network learning algorithm are confirmed very effective to the insertion tasks of electric lines to sleeves as a typical task of active electric power maintenance tasks.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.3
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• pp.267-273
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• 2001

While forecasting sales of a new product is very difficult, it is critical to market success. This is especially true when other products have a highly negative influence on the product because of competition effect. In this paper, we develop a choice-based competitive diffusion model and apply to the case where two digital mobile telecommunication services, that is, digital cellular and PCS services, compete. The basic premise is that demand patterns result from choice behavior, where customers choose a product to maximize their utility. In comparison with Bass-type competitive diffusion models, our model provides superior fitting and forecasting performance. The choice-based model is useful in that it enables the description of such competitive environments and provides the flexibility to include marketing mix variables such as price and advertising.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.69
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• pp.239-259
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• 2016

An increasing number of transactions in the bilateral trade between Korea and China rely on collection and remittance, resulting in an increase in exporters' demand for trade financing. Therefore, there is a need to vitalize forfaiting transactions using drafts or promissory notes, which are based on the collections. In the forfaiting transactions, exporters transfer a payment claim to forfaiters on a non-recourse basis through a without recourse endorsement. However, forfaiters do not know importers' creditworthiness and ability to repay drafts or promissory notes; thus, they need a bank aval as a means of credit support. In forfaiting using aval, the drafts or promissory notes are transferred internationally. However, there is no internationally unified law that regulates drafts and promissory notes, and the governing laws related to such drafts and promissory notes do not accept the "principle of party autonomy." Therefore, there is no other choice but to apply the laws of a certain country, in the event of any dispute relating to such drafts or promissory notes. This paper examined forfaiting using aval from the comparative law perspective, focusing on the "Law of China on Negotiable Instruments." The results of this study may to provide businesses involved in international trade with practical guidance and assistance when using forfaiting with aval, especially in trade with China.