• The KIPS Transactions:PartC
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• v.10C no.2
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• pp.217-232
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• 2003

QoS routing can improve network performance while providing support for QoS guarantees. These benefits, however, comes with additional routing costs such as more complex and frequent route computation and the protocol overheads to exchange dynamic network state information. Moreover, little has been done to mininize the impact of the QoS traffic to the best effort traffic or to enhance the routine Performance of the best effort traffic when QoS routing is deployed. In this paper, it is proposed that a sewer based routing mechanism, which supports the QoS routing without incurring the QoS routing protocol overhead for the network state update exchanges and enhances the performance of the best effort traffic without affecting the performance of QoS routing. Simulation results show that the proposed scheme enhances the routing performance for the QoS traffic while reducing the routing protocol overhead. The routing performance of the best traffic is also improved with virtually no impact to the routine performance of the QoS traffic. The proposed scheme is shown to be especially effective when the ratio of QoS traffic is high, that is, when the impact of the QoS traffic to the performance of best effort traffic is significant.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.8
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• pp.758-767
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• 2012

In the ad-hoc wireless network environment, that the fixed sensor nodes and the sensor nodes to move are mixed, as the number of the sensor nodes with mobility are getting more, the costs to recover and maintain the whole network will increase more and more. This paper proposed the CDSR (Cost based Dynamic Source Routing) algorithm being motivated from the typical DSR algorithm, that is one of the reactive routing protocol. The cost function is defined through measuring the cost which any sensor node pays to participate in the whole network for communication. It is also showed in this paper that the proposed routing algorithm will increase the efficiency and life of whole sensor network through a series of experiments.

• Journal of Navigation and Port Research
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• v.32 no.4
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• pp.295-304
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• 2008

In order to achieve a sustainable competitive advantage in the expanding maritime transportation market, most shipping companies are making every effort to reduce transportation costs. Likewise, the car shipping companies, which carry more than 80% of total car import and export logistics volume, also do their utmost for transportation cost saving. Until now many researches have been made for efficient maritime transportation, but studies for car shipping companies have rarely been made. For this reason, this study has tried to develop a maritime transportation planning support system which can help to save logistics costs and increase a competitive power of car shipping companies. To this end, instead of manual effort to solve the routing problem of car carrier vessels, this study has used an integer programming model to make an optimal transportation planning at the minimum cost. Also in response to the frequent changes both in the car production schedule and ship's arrival schedule after the completion of transportation planning, this research has developed a decision support system of maritime transportation, so that users can easily modify their existing plans.

• Journal of Advanced Navigation Technology
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• v.20 no.6
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• pp.519-527
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• 2016

The present study is concept research on the operation cost management of shipping firms, especially considering technology for economical ship operation of existing ships in units of voyage. The factors that influence economical ship operation management were identified by analyzing the current status of the shipping industry, the development of economical ship operation technologies, technological requirements, and the cost factors of ship operation. Economical operation of existing ships, especially, the economical operation of the units of each voyage, may minimize fuel cost and port charges. This requires low-load streaming cruise control, ballast control, optimal trim, optimal routing, terminal work efficiency improvement, and ship energy management. Optimal routing and terminal work efficiency improvement manage the time saved. To determine the low-load streaming, cruise control, ballast control, optimal trim and ship energy management are meeting the recommendations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11C
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• pp.140-147
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• 2001

In this paper, we propose a scheme of calculating resources\` costs for precomputation in QoS routing schemes. This scheme is effective in respect to the g1oba1 network utilization and the balanced use of network resources. We also propose a QoS routing scheme for transit and intra traffic in a large scale of domain-based network. For a domain in the network, the routing scheme first precomputes multiple paths between all pairs of ingress and egress border routers while considering balancing of the expected load and then selects paths with the probability of path selection. We, therefore, expect that the paths are better than any other paths in respect to reserving the network resources on paths. The routing scheme combines inter and intra domain routings seamlessly and uses the same cost calculation scheme. And for analysis of a load balancing cost calculation proposed a simulation is done.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.1
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• pp.75-79
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• 2010

Wireless sensor networks (WSN) are widely used in many applications. WSN acquires the data of surrounding environments with sensors attached to each node. It is important to design sensor networks that can communicate energy-efficiently as well as to get sensor readings with high accuracy. In this paper, we propose a novel routing scheme that assures high accuracy and significantly reduces data transmission costs in WSN with faults. First, we organize a number of network topologies randomly for routing sensor readings to the base station. Because every sensor node is connected each other with a single path, redundant transmissions are not incurred. It can reduce unnecessary transmissions and guarantee final sensor readings with high accuracy. To show the superiority of our scheme, we compare it with an existing multi-path routing scheme. In the result, our scheme has similar accuracy as the existing scheme and reduces unnecessary data transmissions by about 70% over the existing technique.

• The Journal of the Korea Contents Association
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• v.11 no.7
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• pp.70-79
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• 2011

The multi-path routing schemes that assigns labels to sensor nodes for the reliability of data transmission and the accuracy of an aggregation query over the sensor networks where data transfer is prone to defect have been proposed. However, the existing schemes have high costs for reassigning labels to nodes when the network topology is changed. In this paper, we propose a novel routing method that avoids duplicated data and reduces the update cost of a sensor node. In order to show the superiority of the proposed scheme, we compare it with the existing scheme through the various experiments. Our experimental results show that our proposed method reduces about 95% the amount of the transmitted data for restoration to node failure and about 220% the amount of the transmitted data for query processing over the existing method on average.

• Journal of Advanced Navigation Technology
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• v.19 no.1
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• pp.53-59
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• 2015

We consider the problems that consist of designing time, establishment cost, delay time and reliability in designing a mesh network when given link costs and traffic requirements between nodes. Designing time, establishment cost and delay time are less, reliability is higher in designing a mesh network. One of the problems designing time is solved by mesh network topology optimization and routing (MENTOR) algorithm that Aaron Kershenbaum propose, but the others remain. In this paper we propose a new mesh network design algorithm with small computational complexity that the others are solved. The result of the proposed algorithm is better than MENTOR's in total establishment cost, delay time and reliability.

• Journal of Communications and Networks
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• v.14 no.6
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• pp.629-639
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• 2012

A challenge faced by smart grid systems is providing highly reliable transmissions to better serve different types of electrical applications and improve the energy efficiency of the system. Although wireless networking technologies can provide high-speed and cost-effective solutions, their performance may be impaired by various factors that affect the reliability of smart grid networks. Here, we first suggest the use of IEEE 802.11s-based wireless LAN mesh networks as high-speed wireless backbone networks for smart grid infrastructure to provide high scalability and flexibility while ensuring low installation and management costs. Thereafter, we analyze some vital problems of the IEEE 802.11s default routing protocol (named hybrid wireless mesh protocol; HWMP) from the perspective of transfer reliability, and propose appropriate solutions with a new routing method called HWMP-reliability enhancement to improve the routing reliability of 802.11s-based smart grid mesh networking. A simulation study using ns-3 was conducted to demonstrate the superiority of the proposed schemes.

• 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.