• Journal of the Korea Society of Computer and Information
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• v.17 no.12
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• pp.121-129
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• 2012

In this paper, we proposed WBAN system model to management an application that requires low rate data transfer in IEEE 802.15.4. We have to use different wireless sensor network technology to transfer different date rate and emergency message in medical application service. A suitable system model for WBAN and a WBAN MAC protocol in order to solve these existing system problems are proposed. Firstly, the priority queuing was applied to contention access period, and the system model which could guarantee transmission of a MAC command frame was proposed. Secondly, the MAC frame was newly defined to use the system model which was proposed above. Thirdly, WBAN CSMA/CA back-off algorithm based on data transmission rate was proposed to enhance data throughput and transmission probability of the data frame which does not have priority in the proposed WBAN system. The proposed algorithm is designed to be variable CSMA/CA algorithm parameter, depending on data rate. For the evaluation of WBAN CSMA/CA algorithm, we used Castalia. As a result of the simulation, it is found that the proposed system model can not only relieve loads of data processing, but also probability of collision was decreased.

• Journal of Life Science
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• v.15 no.4 s.71
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• pp.633-640
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• 2005

The purified xylanase from Bacillus pumilus TX703 was modified with various chemical modifiers to determine the active sites of the enzyme. Treatment of the enzyme with group-specific reagents such as carbodiimide or N-bromosuccinimide resulted in complete loss of enzyme activity. These results assumed that these reagents reacted with glutamic acid or aspartic acid and tryptophan residues located at or near the active site. In each case, inactivation was performed by pseudo first-order kinetics. Inhibition of enzyme activity by carbodiimide and W-bromosuccinimide showed non-competitive and competitive inhibition type, respectively. Addition of xylan to the enzyme solution containing N-bromosuccinimide prevented the inactivation, indicating the presence of tryptophan at the substrate binding site. Analysis of kinetics for inactivation showed that the loss of enzyme activity was due to modification of two glutamic acid or aspartic acid residues and single tryptophan residue.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.580-584
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• 2007

The purpose of this study is to analyze managemental problems that were made by cooperator and to offer improvable plan for small and medium construction company. The adapted research method a case study three small and medium contractors and investigate the managemental operation of cooperator and rating standard. Also analyze problem of the rating standard and managemental state of the cooperator and offer improvable plan. The results of this research are as follows. 1)Applying open bid system for supplying low price subcontract for practical rule. 2) Applying rating ratio of subcontract that is followed by receiving status, constructing ability, and selling scale of small and medium construction company for improving working of cooperator.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6B
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• pp.338-348
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• 2005

Currently, IEEE 802.11 Wireless LAN (WLAN) is rising as the most popular means for the broadband wireless access network. In this thesis, we propose a QoS(Quality of Service)-Oriented mechanism using handshaking method of scanning phase in IEEE 802.11 handoff. In conventional process for handoff, the major criterion to select the best AP(Access Point) among candidates is normally based on the RSS(Received Signal Strength), which does not always make the selected network guarantee the maximum achievable performance. Even though the link quality with a neighboring AP is excellent, the AP may not be a good candidate to handoff to simply because MAC(Medium Access Control) protocol of IEEE 802.11 standard is contention-based such as CSMA/CA. Therefore, if we apply network level information to AP selection criteria, we can achieve better handoff efficiency rather than before. The analysis and simulation results applied to our new mechanism show clearly better performance than AP selection based on traditional handoff method.

• Journal of KIISE
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• v.43 no.1
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• pp.27-33
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• 2016

Virtualization has become one of the most helpful techniques in computing systems, and today it is prevalent in several computing environments including desktops, data-centers, and enterprises. However, since I/O layers are implemented to be oblivious to the I/O behaviors on virtual machines (VM), there still exists an I/O scalability issue in virtualized systems. In particular, when a multi-queue solid state drive (SSD) is used as a secondary storage, each system reveals a semantic gap that degrades the overall performance of the VM. This is due to two key problems, accelerated lock contentions and the I/O parallelism issue. In this paper, we propose a novel approach, including the design of virtual CPU (vCPU)-dedicated queues and I/O threads, which efficiently distributes the lock contentions and addresses the parallelism issue of Virtio-blk-data-plane in virtualized environments. Our approach is based on the above principle, which allocates a dedicated queue and an I/O thread for each vCPU to reduce the semantic gap. Our experimental results with various I/O traces clearly show that our design improves the I/O operations per second (IOPS) in virtualized environments by up to 155% over existing QEMU-based systems.

• Journal of the Korean Institute of Gas
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• v.20 no.1
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• pp.52-61
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• 2016

Liquefied petroleum gas is regarded as a promising alternative fuel as it is eco-friendly, has good energy efficiency and output performance, practically and has high cost competitiveness over competing fuels. In spark-ignition engine, direct injection technology improves engine volumetric efficiency apparently and operates engine using the stratified charge that has relatively higher combustion efficiency. This study designed a combustion chamber equipped with visualization system by applying gasoline direct injection engine principle. In doing so, the study recorded and analyzed ignition probability and flame propagation process of spark-ignited direct injection LPG in a digital way. The result can contribute as a basic resource widespread for spark-ignited direct injection LPG engine design and optimization extensively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.11
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• pp.4282-4290
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• 2010

Recently, business environment is spreading from singular business to supply-chain problem. SCM(Supply Chain Management) is changing from closed and static to opened and dynamic environment, so these environment changes of SCM require to enterprise different approach than past. As supply chain is becoming opened and dynamic, a claim is being naming that converse of real-time the get reaction from to recognizing the level of supply chain problem, grope of alternative plan to solving this problem and choosing optimum alternative plan raise the enterprise competitive. But until present, the research to deal with these changes of SCM is on insufficient situation. Thus in this paper proposes the agent system by a way of realizing dynamic supply chain. The agent is going to accomplish the management activities in real-time depends on environment and given condition and designed for solving problems development and maintenance. Also, algorithms performance of the agent is tested on TAC SCM environment. Agents in TAC SCM are simulations of small manufacturers, who must compete with each other for both supplies and customers, and manage inventories and production facilities.

• Journal of Korea Port Economic Association
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• v.34 no.3
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• pp.53-74
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• 2018

The purpose of this study is to give a guiding implications to strengthen the competitiveness of port policy in Philippines, considering the inefficiencies in the port infrastructures and management systems in the country, despite its average economic growth of 5-6% and subsequent increment in passenger and trading volumes. These growth figures imply a compelling need for a systemic development plan and impellent actions. This study used the analytic hierarchy process for conducting a port competitiveness analysis and the data on deterrent factors were collected through literature and internal government documents including on-site interviews of the parties involved. The implications of the analysis led the study to conclude the need for adopting an enhanced centralized management, a separate investment and management for ports, a grade classification of nationwide small-, medium, and large-sized ports, efficient incoming systems for port dues, and an advanced mode of financing and investment inducement, among others.

• Journal of Korea Port Economic Association
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• v.25 no.3
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• pp.207-228
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• 2009

The purpose of this paper is to analyze the concentration effect of Busan container terminal. Productivity and efficiency have played key role to attract more cargo to a port because these are important factors to select liners’ calling port in vessel deployment. It means that productivity directly links with the liners’ vessel operation cost. The main results of this paper are as follows: the port concentration by terminal integration can improve the port's external image with recovering tariff competitiveness and also facilitate economic effect of size through efficient management.

• Journal of Korea Port Economic Association
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• v.32 no.3
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• pp.139-154
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• 2016

The port incentive scheme currently implemented in various Korean ports is used as a marketing tool to increase price competitiveness. Typically, ports implement piecemeal imitation strategies to enhance their competitiveness, rather than a precisely designed system. A precise analysis of the effectiveness of a port's system and scheme redesign are lacking because budget allocation is done without input from customers and freight groups. This study models the incentives faced by ports using a linear programming model. We use the Gwangyang port as the base case. Our analysis of the Gwangyang port reveals that there are insufficient incentives implemented when a traditional qualitative analysis is used. We also identify any excess, deficiency, or absence of the incentive effect for each type of customer and freight group. We find the overall budget of the incentive scheme to be more rational when ports allocate funds to minimize port mileage, and allocate 61.77 percent and 38.23 percent of the budget on existing and new (or increased) cargo inventory, respectively. Future studies can build on our work by further considering basic inputs, and by adding a system to estimate the input data of our model to identify constraints and thus provide a more accurate incentive scheme.