• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.281-290
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• 2002

In this paper, we propose an efficient packet forwarding method for an IP-based wireless Internet access network. Packets are forwarded along with a flow, that is a kind of connection-oriented connection and established before delivering packets. For this purpose, we also propose a flow resolution method and a modified IPv6 header for delivering packet in the wireless Internet access network. In addition, the method to support the mobility of mobile stations is explained, and the implementation issues are discussed. In order to estimate the performance of the proposed method, we analyzed the delay time to deliver packets in the wireless Internet access network. The numerical results show that the proposed method is very efficient, in the view point of delay.

• Journal of Information Processing Systems
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• v.6 no.3
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• pp.307-322
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• 2010

Traffic classification is an essential task for network management. Many researchers have paid attention to initial sub-flow features based classifiers for traffic classification. However, the existing classifiers cannot classify traffic effectively in mobile IP networks. The classifiers depend on initial sub-flows, but they cannot always capture the sub-flows at a point of attachment for a variety of elements because of seamless mobility. Thus the ideal classifier should be capable of traffic classification based on not only initial sub-flows but also various types of sub-flows. In this paper, we propose a classifiable sub-flow selection method to realize the ideal classifier. The experimental results are so far promising for this research direction, even though they are derived from a reduced set of general applications and under relatively simplifying assumptions. Altogether, the significant contribution is indicating the feasibility of the ideal classifier by selecting not only initial sub-flows but also transition sub-flows.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.8
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• pp.509-514
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• 2010

A numerical simulation of passenger evacuation in a subway station was performed by coupling the passenger flow analysis and the fire simulation. The algorithm of the passenger flow analysis was based on a DEM (Discrete Element Method) using the potential map of the direction vector for each passenger. This algorithm was improved in the present study as to use finer grid smaller than a passenger in order to resolve detailed geometry of the station and to resolve the behavior of passengers in the bottleneck at the ticket gate considering the collision of passengers to a wall or with other passengers. In the fire simulation, the CO distribution predicted by using CFD was used to take into account the effect of toxic gases on the passengers' mobility. The methodology proposed in the present study could be used in designing safer subway station in case of fire occurrence.

• Journal of Communications and Networks
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• v.15 no.2
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• pp.173-178
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• 2013

It is a concern that eco-driving vehicles, because their driving behavior differs from other vehicles due to e.g. e-start, may inhibit smooth traffic flow. Therefore, it is necessary to study the cooperative eco-driving done by a vehicle group, putting "vehicle-to-vehicle communication" and "road-to-vehicle communication" into perspective. Based on these factors, this study aimed to: 1) Analyze fuel consumption rates and driving behaviors of more than one vehicle following an Eco-Driving vehicle. 2) Examine the effect of information on the fuel consumption rate of the preceding vehicles on the following vehicles. As a result, the following findings were obtained: 1) By providing information to multiple following vehicles, the fuel consumption rate of the second vehicle was not lowered, while that of the third one was. 2) It is possible that, when information on fuel consumption of a preceding vehicle is provided to the following one, an inter-vehicular distance is shortened during deceleration to contribute to smooth traffic flow. From the above results, it is suggested that, when targeting a vehicle group, sharing the information on preceding vehicles is effective.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.3
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• pp.15-20
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• 2007

Low temperature processed ZnO-TFTs on glass below $270^{\circ}C$ for plastic substrate applications were fabricated and their electrical properties were investigated. Films in ZnO-TFTs with bottom gate configuration were made by RF magnetron sputtering system except for $SiO_2$ gate oxide deposited by ICP-CVD. ZnO channel films were grown on glass with various Ar and $O_2$ flow ratios. All of the fabricated ZnO-TFTs showed perfectly the enhancement mode operation, a high optical transmittance of above 80% in visible ranges of the spectrum. In the ZnO-TFTs with pure Ar process, the field effect mobility, threshold voltage, and on/off ratio were measured to be $1.2\;cm^2/Vs$, 8.5 V, and $5{\times}10^5$, respectively. These characteristic values are much higher than those of the ZnO-TFTs of which ZnO channel layers were processed with additional $O_2$ gas. In addition, ZnO-TFT with pure Af process showed smaller swing voltage of 1.86v/decade compared to those with $Ar+O_2$ process.

• Journal of KIISE:Information Networking
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• v.32 no.1
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• pp.80-88
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• 2005

In ubiquitous spaces, a user wants to be provided with a VOD service while moving one space to another freely. Since the traditional VOD system is dependent on user location, the VOD server transmits video data to a single client during a session. If the user moves to another space, he/she should close the old session and make a new request for the same video. However, the location-aware VOD system supports user mobility by closing and opening the session automatically. That is, the VOD system automatically perceives the movement of a user and allows the server to change the data flow so that a client near the user can receive the video data. This paper proposes a location-aware VOD service architecture and a session handoff scheme to provide a mobile user with continuous video delivery and implements a location-aware VOD prototype system based on Jini and Java. In experiment, we show that the proposed handoff scheme has a smaller handoff delay than the other handoff scheme.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.20 no.1
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• pp.21-26
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• 2014

Background: This study was aimed to determine the effects of deep abdominal muscle exercises (DAME) and thoracic mobility exercises (TME) on pulmonary function. Methods: This study was conducted with 22 college students who are in their 20s and have no problem carrying out activities of daily living. All subjects were randomly assigned to either the DAME group (11) or the TME group (11) to undertake the exercises for 2 weeks. To measure pulmonary function of subjects, forced vital capacity (FVC), forced exploratory volume in 1 second (FEV1) and peak expiratory flow (PEF) were measured using chest graph. Chest expansion of subjects was also measured with tape ruler. These measurements were performed on the first day before the exercise program started and on the next day after the 2-week exercise program was completed. A paired-t test was performed to compare the differences in pulmonary function before and after the exercise program, and an independent t-test was performed to compare the two groups. Results: The results of this study were as follows: 1) In comparison of pre- and post-exercise changes in the DAME and TME groups, both groups showed significant increase in chest expansion and PEF after the exercise program, compared with the baseline data (p<.05). Both groups also demonstrated improvements in FVC and FEV1 after the exercise program, compared with the baseline data. However, the differences were not statistically significant (p>.05). 2) The comparison of the DAME and TME groups revealed no significant differences in chest expansion, FVC, FEV1 and PEF (p>.05). Conclusion: It is therefore concluded that both DAME and TME were effective in improving pulmonary function.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.1
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• pp.101-110
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• 2019

PURPOSE: This study was conducted to analyze the effects of virtual reality inspiratory muscle training and conventional inspiratory muscle training on diaphragm movement and pulmonary function in patients with thoracic restriction. METHODS: This study measured diaphragm movement, forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), peak expiratory flow (PEF), and thoracic mobility (upper, middle, and lower trunk) under two different conditions. Forty young women between 19 and 24 years of age who had no history of orthopedic symptoms for the last 6 months were divided into experimental and control groups. The experimental group performed virtual reality inspiratory muscle training and diaphragm breathing, and the control group performed conventional inspiratory muscle training and diaphragm breathing. RESULTS: The control group showed a significant increase in all dependent variables except for lower trunk mobility and PEF. The experimental group showed a significant increase in all dependent variables except for lower trunk mobility. Particularly, the experimental group showed significant increases in diaphragm movement (p<.05), FVC (p<.05), FEV1 (p<.05), and PEF (p<.05) relative to the control group. CONCLUSION: We recommend inspiratory muscle training with a virtual reality program over conventional training to improve diaphragm movement and pulmonary function in patients with thoracic restriction.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.2
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• pp.1-7
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• 2019

Recently, multimedia streaming service has been activated, and the demand for high-quality multimedia convergence contents services is predicted to increase significantly in the future. The issues of the increasing network load due to the rise of multimedia streaming traffic must be addressed in order to provide QoS guaranteed services. To do this, an efficient network resource management and mobility support technologies are needed through seamless mobility support for heterogeneous networks. Therefore, in this paper, an MIH technology was used to recognize the network situation information in advance and reduce packet loss due to handover delays, and an ACLMIH-FHPMIPv6 is designed that can provide an intelligent interface through introducing a hierarchical mobility management technique in FPMIPv6 integrated network.

• Journal of Hydrogen and New Energy
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• v.35 no.3
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• pp.290-299
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• 2024

In this study, a theoretical study was conducted on the pre-cooling temperature of hydrogen gas and the heat exchanger area in a small-scale liquefied hydrogen system. The small-scale liquefaction system was built and liquid hydrogen production experiments were performed. In this process, the temperature of precooled hydrogen gas was measure to be about 120 K, and then the possibility of a cause was analyzed through pressure analysis of hydrogen gas and container, and analysis of the amount of liquid hydrogen produced. It was found that some reasonable results were obtained from the theoretical approaches. Based on this theoretical approach, we aim to improve the production of liquid hydrogen by optimizing the heat exchange area according to flow rate.