• Journal of Navigation and Port Research
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• v.33 no.6
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• pp.375-380
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• 2009

The authors had consisted the construction of shipyard must be investigated under the consideration of long term ship's demand and so the Floating Dock might be an alternative to the dry dock. This paper shows a development of Floating Dock Controller for Skid Launching System(SLS). While loading out a block to the Floating Dock and launching ship from the Floating Dock, the balancing of the ship and the dock is very important and achieved by adjusting the Ballast tank of the Floating Dock In this paper a Floating Dock Controller for SLS was developed through the on-line interface of VRC(Valve Remote Control), Tank Level & Draft Measuring System and Valve Control algorithm on Tank Plan. The control system developed was applied to a shipbuilding and verified good and stable.

• Composites Research
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• v.35 no.5
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• pp.340-346
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• 2022

In this study, an optimal structural design of composite helicopter blades is performed using the genetic algorithm-based optimizer PSGA (Particle Swarm assisted Genetic Algorithm). The blade sections consist of the skin, spar, form, and balancing weight. The sectional geometries are generated using the B-spline curves while an opensource code Gmsh is used to discretize each material domain which is then analyzed by a finite element sectional analysis program Ksec2d. The HART II blade formed based on either C- or D-spar configuration is exploited to verify the cross-sectional design framework. A numerical simulation shows that each spar model reduces the blade mass by 7.39% and 6.65%, respectively, as compared with the baseline HART II blade case, while the shear center locations being remain close (within 5% chord) to the quarter chord line for both cases. The effectiveness of the present optimal structural design framework is demonstrated, which can readily be applied for the structural design of composite helicopter blades.

• Journal of Energy Engineering
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• v.26 no.3
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• pp.64-70
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• 2017

The concept of Hybrid Safety Injection Tank (Hybrid SIT) proposed by the Korea Atomic Energy Research Institute (KAERI) has been introduced for the purpose of application to the Advanced Power Reactor Plus (APR+). In this study, the SBO situation of the APR+ was analyzed by using the MARS-KS code in order to evaluate whether the operation of the Hybrid SIT has an effect on the cooling performance of the Reactor Coolant System (RCS). According to the analysis, when the actuation valve on the pressure balancing line (PBL) is opened, the Hybrid SIT's pressure rises rapidly, forming equilibrium with the RCS pressure; subsequently, a flow is injected from the Hybrid SIT into the reactor vessel through the direct vessel injection (DVI) line. The analysis showed that it is possible to keep the core temperature below melting temperature during the operation of a Hybrid SIT.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.559-562
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• 2017

In city, tracing of power transmission lines is difficult due to compound installation of overhead and underground lines, transposition, bad view caused by trees or big buildings. It is hard problem for electrical technician on site to trace power transformers or power lines to serve customers in 3 phase -4 wires power distribution systems. It is necessary that the correct and fast tracing method is required for load balancing among distribution lines. Old technology use to trace off-lines with high power impulse injection. Our proposed method use to trace live lines with very small power high frequency signal injection. Typical power transformers in the distribution system prevent propagating the higher frequency carrier signal. The proposed method uses the limited propagation ability to identify the power transformer to serve customers. Two end communication terminals are required to be synchronized between them for determination on electrically same phases. Challenging issue is to achieve synchronization without GPS providing synchronizing time. A novel power transformer and wire identification system is designed and implemented. The system consists of a transmitter and a receiver with power-line communication module. Some experiments are conducted to verify the theoretical concepts in a big commercial building. Also some simulations are done to help and understand the concepts by using MATLAB Simulink simulator.

• Journal of Korea Game Society
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• v.4 no.4
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• pp.11-18
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• 2004

The on-line games in the past were played by only two persons exchanging data based on one-to-one connections, whereas recent ones (e.g. MMORPG: Massively Multi-player Online Role-playings Game) enable tens of thousands of people to be connected simultaneously. Specifically, Korea has established an excellent network infrastructure that can't be found anywhere in the world. Almost every household has a high-speed Internet access. What made this possible was, in part, high density of population that has accelerated the formation of good Internet infrastructure. However, this rapid increase in the use of on-line games may lead to surging traffics exceeding the limited Internet communication capacity so that the connection to the games is unstable or the server fails. expanding the servers though this measure is very costly could solve this problem. To deal with this problem, the present study proposes the load distribution technology that connects in the form of local clustering the game servers divided by their contents used in each on-line game reduces the loads of specific servers using the load balancer, and enhances performance of sewer for their efficient operation. In this paper, a cluster system is proposed where each Game server in the system has different contents service and loads are distributed efficiently using the game server resource information such as CPU utilization. Game sewers having different contents are mutually connected and managed with a network file system to maintain information consistency required to support resource information updates, deletions, and additions. Simulation studies show that our method performs better than other traditional methods. In terms of response time, our method shows shorter latency than RR (Round Robin) and LC (Least Connection) by about 12%, 10% respectively.

• Journal of KIISE:Information Networking
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• v.35 no.5
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• pp.384-394
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• 2008

A wireless router is a device which allows several wireless clients to share an internet line using NAT (Network Address Translation). In a school or a small office environment where many clients use multiple wireless routers, a client may select anyone of wireless routers so that most clients can be clustered to a small set of the wireless routers. In such a case, there exists load unbalancing problem between clients and wireless routers. One of its result is that clients using the busiest router get poor service. The other is that the resource utilization of the whole wireless routers becomes very low. In order to resolve the problems, we propose a load sharing scheme to maximize network bandwidth utilization based on multiple SSID. In a time internal, the proposed scheme keeps to show the available bandwidth information of all the possible wireless routers to clients through multiple SSID. A new client can select the most available band with router. This scheme allows to achieve a good load balancing between clients and routers in terms of bandwidth utilization. We implemented the proposed scheme with ASUS WL 500G wireless router and performed experiments. Experimental results show the bandwidth utilization improvement compared to the existing method.

• Geophysics and Geophysical Exploration
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• v.4 no.2
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• pp.25-33
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• 2001

Loop-loop electromagnetic (EM) survey in frequency domain has been carried out in order to provide basic solution to geotechnical applications. Source and receiver configuration may be horizontal co-planar (HCP) and/or vertical co-planar (VCP). Three quadrature components of mutual impedance ratio for each configuration are used to construct the subsurface image. For the purpose of obtaining the model response and validating the reasonable performance of the inversion, we obtained each responses of two-layered and three-layered earth models and two-dimensional (2-D) isolated anomalous body. The response of 2-D isolated anomalous body has been calculated using extended Born approximation for the solution of 2.5-D integral equation describing EM scattering problem. As a result of the least-squares inversion with variable Lagrangian multiplier, we could construct more resolvable image from HCP data than VCP data. Furthermore, joint inversion of HCP and VCP data made better stability and resolution of the inversion. Resistivity values, however, did not exactly match the true ones. Loop-loop EM field data was obtained with EM34-3XL system manufactured by Geonics Ltd. (Canada). Electrical resistivity survey was conducted on the same line for the comparison in advance. Since the constructed image from loop-loop EM data by 2-D inversion algorithm showed almost similar resistivity distribution to that from electrical resistivity one, we expect the developed 2.5-D loop-loop EM inversion program can be applied for the reconnaissance site survey.

• Sleep Medicine and Psychophysiology
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• v.17 no.2
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• pp.85-90
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• 2010

Objectives: Ginseng has a long history of being used in insomnia treatment and there is some evidence from animal studies of its sleep-enhancing property. From this, it can be assumed that ginseng has sleep-promoting effect in humans. The purpose of this study was to investigate the effect of Korean red ginseng on change of sleep architecture in humans. Methods: A total of 20 healthy young males with regular sleep and wake habits and without any psychiatric nor cognitive problems were selected based on review of sleep questionnaires and sleep diaries they completed followed by an interview with a board-certified psychiatrist. The subjects were randomly assigned to red ginseng or placebo for 2 weeks of trial. The total daily dose of ginseng was 4,500 mg. The polysomnographic recordings were made at baseline and at 2 weeks after. The effects of red ginseng and placebo on sleep were assessed by comparing the changes in polysomnographic variables between the two groups. Results: A total of 15 subjects, 8 from red ginseng group and 7 from placebo group, were included to undergo polysomnographic procedures. The red ginseng group showed tendencies to increase stage 3 sleep (p=0.087) and to decrease stage 2 sleep (p=0.071) from the baseline compared with the placebo group. Conclusion: Korean red ginseng tends to increase deep sleep and decrease shallow sleep. Our result is in line, at least in part, with previous findings that Korean red ginseng increased total and NREM sleep in rats. Further studies with higher ginseng dosage, larger sample size and longer trial duration should be conducted to confirm the sleep stabilizing and balancing effects of Korean red ginseng.

• Asia pacific journal of information systems
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• v.17 no.3
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• pp.25-53
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• 2007

The Expectation Confirmation Model (ECM) of information systems investigates the continued information systems usage behavior. This paper expands the original post-adoption beliefs and searches the applications in the emerging hedonic information systems. Previous IS researches focused on the organizational environments. However as the information technology (especially internet) evolves, information systems have not only emerged for the organizations but also for the individual users, such as internet portals, internet communities, on-line games etc. These information systems so called Hedonic Information Systems aims to provide self-fulfilling value rather than instrumental value to the users. Researches in other disciplines, including marketing and consumer behavior research, illustrate that the hedonic and utilitarian perspective of goods and services have different influence on the consumer behavior. Goods and services used to be classified into either hedonic or utilitarian aspect but now they may belong to both aspects simultaneously. Moreover consumer's goals or tasks have both hedonic utilitarian aspects. When a consumer makes a decision to purchase or repurchase goods or services, he/she compares the hedonic and utilitarian perspectives of goods to find most suitable ones to satisfy their goals/tasks. Finally, consumer's behavior is determined by the trade-off between what the goods can provide to the consumers and in what extent the goods fulfill consumer's purchase behavior. Consumer also shows that the salience of hedonic perspective is relatively greater when consumer decides which of several items to give up (forfeiture choices) than the time when they decide which item to acquire (acquisition choices). Some researches in MIS discipline have found out that the information systems also have both hedonic and utilitarian perspectives. The decision process of whether to use information systems or not is similar to that of a consumer's decision of purchasing or repurchasing goods or services. However most of researches in MIS tend to focus on the extrinsic motivation variables which only cover the utilitarian perspective of information systems. It is only recent that researches start to investigate the intrinsic motivation variable - Perceived Enjoyment - for the hedonic perspective. Considering the consumer's purchasing decision process, users of information systems evaluate the systems through balancing between intrinsic (hedonic) and extrinsic (utilitarian) variables according to their main tasks or tendencies. This paper proposes a model that is based on the ECM of IS Continuance model modified from Expectation Confirmation Model to fit into the continued usage of information system. It first started from the decision process regarding hedonic and utilitarian perspectives in the consumer behavior literatures. The model deals with continued usage of information systems beyond the mere technology adoption as in most of the previous MIS researches. This research is particularly important to the hedonic information systems, because their business model depends on the frequent usages rather simple adoption at the beginning. Because the basic model only considered the extrinsic motivations (perceived usefulness) to explain the users' behavior and as the information systems can have both hedonic and utilitarian dimensions, it should consider both perspectives. Therefore, this newly proposed model considers intrinsic variable (perceived enjoyment) as well. Since the individual user can have a preference on either aspects that is between the hedonic and utilitarian perspective depending on his/her main tasks or goals, some variables (Hedonic Orientation and Utilitarian Orientation) meaning the extents of users' pursuing from the information system were additionally studied.