• Journal of Internet Computing and Services
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• v.7 no.3
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• pp.31-39
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• 2006

Ubiquitous and pervasive environment presents opportunities for a rich set of location aware applications such as car navigation and intelligent robots, interactive virtual games, logistics service, asset tracking etc. Typical indoor location systems require better accuracy than what current outdoor location systems provide, Outdoor location technologies such as GPS have poor indoor performance because of the harsh nature of indoor environments, In this paper we present a novel reducing interference location system that is particularly well suited to support context aware computing. The system, called EEM (Enhance Envelop Method) alms to combine the advantages of real time tracking systems that implement distributed environment with the suitability of infrastructure sensor network.

• Journal of Navigation and Port Research
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• v.35 no.1
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• pp.71-76
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• 2011

Recently, container terminal managers make an experiment on the double cycle and dual cycle operation, which ship loading and unloading were carried out simultaneously, for increasing the productivity of quay side. If, however, we make an experiment on dual cycle operation in a real job site, the efficiency is poor up to terminal operation method as YTs(Yard Tractors)' allocation method, QCs(Quay Cranes)' working speed, and position of export containers. Especially, using the existing yard operation method, it is difficult to support to dual and double cycle operation. Therefore, this paper examine more efficient terminal operation method, when terminal uses dual cycle operation. We developed a simulation model using simulation analysis software, Arena.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.170-171
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• 2011

Recently, container terminal managers make an experiment on the double cycle and dual cycle operation, which ship loading and unloading were carried out simultaneously, for increasing the productivity of quay side. If, however, we make an experiment on dual cycle operation in a real job site, the efficiency is poor up to terminal operation method as YTs(Yard Tractors)' allocation method, QCs(Quay Cranes)' working speed, and position of export containers. Especially, using the existing yard operation method, it is difficult to support to dual and double cycle operation. Therefore, this paper examine more efficient terminal operation method, when terminal uses dual cycle operation. We developed a simulation model using simulation analysis software, Arena.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.3
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• pp.10-19
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• 2009

Wireless LAN systems have been widely implemented for supporting the wireless internet services especially in the hotspot areas such as hospitals, homes, conference rooms, and so on. Compared with wired LAN systems, wireless LAN systems have the advantages of the users' mobility support and low implementation and maintenance costs. IEEE 802.11 wireless LAN systems employ the backoff algorithm to avoid contentions among STAs when two or more STAs attempt to transmit their data frames simultaneously. The MAC efficiency can be improved if the CW values are adaptively changed according to the channel state of IEEE 802.11 wireless LANs. In this paper, a dynamic contention window control algorithm is proposed using the genetic algorithm to improve the MAC throughput of IEEE 802.11 wireless LANs.

• Journal of Navigation and Port Research
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• v.38 no.2
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• pp.177-184
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• 2014

Recently, brand equity is paid much attention in various industries. However, container liner shipping companies are still unfamiliar with this concept, and also the brand equity model has not been tested yet in shipping context. This study, therefore, aims to measure the relative importance of brand equity factors of container liner shipping companies by employing AHP (Analytic Hierarchy Process). This study concludes that perceived quality, in particular cost-related service quality, is the most influential factor of brand equity, while weak support is found for brand association. In addition to this, group comparisons were conducted between shipping companies, freight forwarders and academics. The results will be useful as they firstly define brand equity and its role in shipping context, highlighting the significance of brand management to container liner shipping firms. This evaluation is not an end in itself, but will eventually be utilised as a tool to build competitive advantage which cannot be easily imitated by competitors.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.12
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• pp.6169-6187
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• 2017

With the fast growth of mobile services, Mobile Cloud Computing(MCC) has gained a great deal of attention from researchers in the academic and industrial field. User authentication and privacy are significant issues in MCC environment. Recently, Tsai and Lo proposed a privacy-aware authentication scheme for distributed MCC services, which claimed to support mutual authentication and user anonymity. However, Irshad et.al. pointed out this scheme cannot achieve desired security goals and improved it. Unfortunately, this paper shall show that security features of Irshad et.al.'s scheme are achieved at the price of multiple time-consuming operations, such as three bilinear pairing operations, one map-to-point hash function operation, etc. Besides, it still suffers from two minor design flaws, including incapability of achieving three-factor security and no user revocation and re-registration. To address these issues, an enhanced and provably secure authentication scheme for distributed MCC services will be designed in this work. The proposed scheme can meet all desirable security requirements and is able to resist against various kinds of attacks. Moreover, compared with previously proposed schemes, the proposed scheme provides more security features while achieving lower computation and communication costs.

• Journal of Distribution Science
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• v.17 no.12
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• pp.43-54
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• 2019

Purpose: Marine transportation companies must improve service quality to secure competitive advantage and continuous relationships with customers. This study explores the value and necessity of service quality in the industry by empirically identifying the factor that would have the largest effect on the improvement of service quality, also examining whether such improvement may actually influence continuous relationships. Research design, data and methodology: Based on an online survey with those in the Korean marine transportation industry, this study conducted statistical analyses using structural equation modeling. Based on relevant previous studies, the current study constructed a total of 55 survey questions. Finally, 281 questionnaires were collected, but 68 were excluded owing to invalid responses. Results: Information service attribute had the largest effect on service quality, whereas communication did not demonstrate a significant influence. In addition, distribution and information services exerted a positive effect on service satisfaction through service quality, and finally influenced relationship continuity. Conclusions: The results shows that marine logistics service quality strategies which were centered on time or local factors, should be considered in terms of the development of innovative services. In particular the improvement of information service systems and strategies in changed business environment.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.4
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• pp.456-470
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• 2017

We propose some countermeasures needed to cope with fortifying international regulations for fisheries subsidies. The government should rigorously select the recipients of fisheries subsidies to ensure that they are not engaged in ineffective projects by resorting to subsidies. On the other hand, the government should make the individual applicant's application for the subsidies easier by exempting them from the submission of a burdensome feasibility report. As for the strengthening regulatory international movements against the fisheries subsidies, we can consider the following countermeasures. One is not to designate and provide prohibitive subsidies in such a way that violates international norms. The other one is to reform the domestic fisheries subsidies system in Korea with the following points considered. It should be considered that fisheries subsidies, which can be categorized as the actionable subsidies, should not be granted to the items that can be exported but to the items that can be used for domestic consumption or processing. In the case of non-actionable subsidies, the subsidies are mainly allowed for promotion of public-sector research and development, regional development, and adaptation to new environmental regulations. Thus, the non-actionable subsidies should be designated in the consideration of the allowances for these activities.

• Journal of Digital Convergence
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• v.12 no.3
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• pp.69-77
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• 2014

Because smart televisions (TVs) have various and innovative functions that are different from traditional TVs, consumers are front with a complex decision-making problem when they want to buy a best TV among alternatives made by many TV makers. TV manufactures have developed and announced different types of smart TV models and they need a comparative study for evaluating their characteristics. In this paper, we suggest the Analytic Hierarchy Process(AHP) method for deciding the best smart TVs regarding many selection criteria. The method provides a decision support for consumers who like to purchase a smart TV. We describe criteria affecting the smart TV selection through a literature review and suggest a user testing method in order to derive accurate judgments from consumers. Using the Expert Choice software package, we show a an numerical example how the priority of smart TVs are computed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.142-143
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• 2017

As weapons systems are fused with advanced technologies, many of the expenses for research and development are favorites, and that group demands high reliability of weapons systems before the lifecycle. However, empirical studies on the reliability of defense weapons systems are restricted to lack of attention and limitation of data. In this research, we proposed the process of collecting field operation specifications based on the experience gathered by visiting directly to the weapons system operator's trap, strategy and maintenance support force (COMROKFLT, Naval Logistics Command, Naval Shipyard, production company). We used this to derive the operation MTBF of the solubility inducing bullet shooting system and compared it with the target value at the time of development.