• Journal of KIISE:Information Networking
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• v.37 no.4
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• pp.272-283
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• 2010

Wireless Mesh Networks (WMNs) have gained a lot of attention recently. Based on the characteristic of WMNs as a highly connected wireless infrastructure, many efforts from research organizations are made in order to improve the performance of the flow throughput in WMNs. Therefore, it is very critical issue to establish efficient routing paths for multiple concurrent ongoing flows. In this paper, we propose a general modeling methodology to analyze the end-to-end throughput of multiple concurrent flows by analytical calculation taking into account the carrier sensing behaviors, interference and the IEEE 802.11 Distributed Coordination Function mechanism. After the comparison of the average service time for each successful transmission at each node, we analyze the bottlenecks of flows, and hence obtain the maximum end-to-end throughput of them. By using our proposed model, it is possible to predicate the throughput of several candidate routing paths for multiple concurrent ongoing data flows, so we can select the most efficient route that can achieve the highest throughput. We carry out simulations with various traffic patterns of multiple flows in WMNs to validate our modeling and our efficient route selection mechanism.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.2
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• pp.213-220
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• 2016

The needs for the utilization of space in the urban ara due to the increasing population and traffic volume. A Double-deck tunnel can be an appropriate solution. Geosynthetics are inevitably installed between ground and tunnel lining, therefore, geosynthetic-soil interface is also comprises. Dynamic shear behavior of geosynthetic-soil interface affects the dynamic behavior of tunnel, and experimental study is required since the behavior is very complicated. In this study, chemical factors such as acid and basic element in the groundwater and temperature are considered in the laboratory test. Multi-purpose Interface Apparatus(M-PIA) is utilized and submerging periods are 60 and 960 days. Consequently, dynamic shear degradation of geosynthetic-soil interface considering chemical and thermal factors are verified.

• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.537-543
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• 2007

It's an important part to calculate the weights between criterions and to aggregate the decision inputs in a MCDM(Multi criterion decision making) This paper presents a method for aggregation cf decision inputs and application to the MCDM. We incorporate the fuzzy set theory and the basic nature of subjectivity due to ambiguity to achieve a flexible decision approach suitable for uncertain and fuzzy environments. To obtain the scoring that corresponds to the best alternative or the ranking of the alternatives, we need to use a total order for the fuzzy numbers involved in the problem. In this article, we consider a definition of such a total order, which is based on two subjective aspects: the degree of optimism/pessimism reflected with the ordered weighted averaging(OWA) oprators. A numerical example, expecially location analysis for anchorage area, is given to illustrate the approach.

• Journal of Trauma and Injury
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• v.23 no.1
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• pp.6-15
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• 2010

Purpose: Trauma is one of the leading causes of death, especially among young people. Life-threatening conditions are very common in multiple-traumatized patients due to concurrent multi-organ injuries. Treating such severely injured patients is time critical. However, in Korea, the transfer of severely injured patients is not uncommon due to the lack of a mature trauma care system. In developed countries, the preventable trauma death rate is very low, but the rate is still very high in Korea. This study's objective was to demonstrate the current serious state in which severely injured patients have to be transferred from a Regional Emergency Medical Center even though it actually serves as a trauma center. Methods: Ajou University Medical Center is a tertiary hospital that serves as a trauma center in Gyeonggido. The medical records at Ajou University Medical Center for a 1-year period from January 1, 2008, to December 31, 2008, were retrospectively reviewed. A severely injured patient was defined as a patient who showed more than 15 point on the ISS (injury severity score) scale. We investigated the clinical characteristics of such patients and the causes of transfer. Results: Out of 81,718 patients who visited the Regional Emergency Medical Center, 19,731 (24.1%) were injured patients. Among them, 108 severely-injured patients were transferred from one Regional Emergency Medical Center to other hospitals. The male-to-female ratio was about 3.5:1, and the mean ISS was 23.08. The most common mechanism of injury was traffic accidents (41.7%). A major cause of transfer was the shortage of intensive care units (44.4%); another was for emergent operation (27.8%). Most of the hospitals that received the severely-injured patients were secondary hospitals (86.1%). Conclusion: Although the Regional Emergency Medical Center played a role as a trauma center, actually, severely-injured patients had to be transferred to other hospitals for several reasons. Most reasons were related with the deficiencies in the trauma care system. If a mature trauma care system is well-organized, the numbers of transfer of severely injured patients will be reduced significantly.

• Journal of Cadastre & Land InformatiX
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• v.47 no.1
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• pp.127-142
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• 2017

The purpose of this study is to examine the status of urbanization of Namyangju-Si from 2001 till 2008, analyze the correlation of the change of surrounding land use according to the change of accessibility and analyze the correlation of the change of land use. Based on the result from correlation analysis, I simulated from the view point of interactions between agents of land use and transportation accessibility by using MAS. I tried to forecast, based on space, the change of surrounding land use caused by the change of accessibility. I conducted landscape analysis by using a land registration map. Also, I conducted GIS analysis statistical analysis simulation analysis of traffic data, land use data in order to analyze the correlation of the change of surrounding land use according to the change of accessibility. I could find out a certain pattern that new roads and railroads causes the within 500m adjacent land to change into urban land use, which led me to construct a system through which land use changing phenomenon can be expected according to the change of accessibility. It is expected that it can make the best use of selecting the location where new transportation facilities are constructed.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.146-153
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• 2009

Recently, the research relative to NGN(Next Generation Network) is progressing in 3GPP(The 3rd Generation Partnership Progect), IETF(Internet Engineering Task Force), and so on. Although user needs frequently mobility which is various service pattern, In accordance with the development of these various applications, IMS(IP Multimedia Subsystem) and hierarchical networks ie, Femtocell/WiBro/3G etc is constructed for more user demands which provide service in anytime, anywhere. It is necessary to optimum network selection criterion which consider to wireless signal quality add to user service profile and service network traffic balance. NGN also needs a method to perform heterogeneous handover and to constraint Ping-pong phenomenon when using existing terminal-based handover decision. This paper proposes scheme for network selection and heterogeneous handover procedure in hierarchical wireless multi-access network based on SIP-MIH(Session Initiation Protocol-Media Independent Handover) with IMS by using user service profile that the considerations are dealing with not only selection and registration of various access network but also easy of developing the terminal.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.4
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• pp.337-346
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• 2020

Traffic jam and congestion in urban areas has caused the need to improve the utility of underground space. In response, research on underground structures is increasingly being conducted. Notably, a double-deck tunnel is one of the most widely used of all those underground structures. This double-deck tunnel is separated by the middle slab into the upper and lower roadways. Both vehicle load and earthquake load cause the middle slab to exhibit dynamic behavior. Earthquake-related response characteristics, in particular, are highly complex and difficult to interpret in a theoretical context, and thus experimental research is required. The aim of the present study is to assess the stability of a double-deck tunnel's middle slab of the Collapse Prevention Level and Seismic Category 1 with regard to the presence of vibration-damping Rubber Bearings. In vibration table tests, the ratio of similitude was set to 1/4. Linings and vibrating platforms were fixed during scaled model tests to represent the integrated behavior of the ground and the applied models. In doing so, it was possible to minimize relative behavior. The standard TBM cross-section for the virtual double-deck tunnel was selected as a test subject. The level of ground motion exerted on the bedrock was set to 0.154 g (artificial seismic wave, Collapse Prevention Level and Seismic Category 1). A seismic wave with the maximum acceleration of 0.154 g was applied to the vibration table input (bedrock) to analyze resultant amplification in the models. As a result, the seismic stability of the middle slab was evaluated and analyzed with respect to the presence of vibration-damping rubber bearings. It was confirmed that the presence of vibration-damping rubber bearings improved its earthquake acceleration damping performance by up to 40%.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.5
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• pp.13-21
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• 2013

Super high-rise buildings of combined use such as large shopping malls and multiplex etc. have larger parking facilities than general buildings and are characteristic of an increase in the number of the entrance and the exit connecting internal external space of the parking lot. These features cause a congestion of internal traffic by increasing car driving distance in the parking lot, and vehicle idling increases by drivers wander the parking lot in order to find parking space. In addition, they make drivers suffer from lots of difficulties due to parking including increasing their walking line after parking. Therefore, in this study, we developed individual parking information provision algorithm to specify the optimal parking place for drivers according to the purpose of visiting a building and the drivers' moving path, and selected new construction site for the second lotte world in order to evaluate the algorithm developed and performed evaluation. As a result of the evaluation, it was analyzed that in the case of applying the individual parking information provision algorithm compared to the existing parking information provision algorithm, moving distance in the parking lot decreases around 7.43~83.4%, and that in the case of $CO_2$ emission, it decreased about 47.7% on average, which indicates that the efficiency resulted from application of the individual parking information provision algorithm is very high as the application effects are tested.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.543-551
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• 2012

Road pavements in Korea generally show shorter service life than the predicted one. There are many reasons for this phenomenon including increased traffic load and other attacks from exposure conditions. In order to extend a service life and upgrade the pavement, a new multi-functional composite pavement system is being developed in Korea. This study is to investigate the performances of fiber-reinforced lean concrete for pavement base. This study considered mineral admixtures of fly ash and reject ash. The reject ash is defined as ash that does not meet the specifications for fly ash so that it cannot be used as a supplemental material for cement replacement. Due to the inherent property of lean concrete, compaction during the fabrication of specimens is a key factor. Therefore, this study suggests an appropriate compaction method. From the test results, the compressive strengths of the concrete satisfied the required limit of 5 MPa at 7 days. When a compaction roller was used to mimic actual field conditions, the strength development seemed to be influenced by the compaction energy rather than hydration of cement itself.

• The Journal of the Korea Contents Association
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• v.16 no.4
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• pp.442-454
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• 2016

Recently, due to the increment of national income and the living standard of citizens, the leasure business has been dramatically expanded. Among the business, inland water activities such as cruise tour or water taxi have drawn attention from the people. As more people come for a new pleasure, the frequency and the number of services continues to rise yet the safety of people values less recently. In fact, the number of relating accidents also has risen accordingly. In order to prevent such accidents in inland waters, the vessels' real time voyage data, the advanced warning system and the emergency rescuing system are required. In this paper, we have developed navigation guiding application for safety of passengers and vessels in inland waters. Navigation guiding applications not only provide Inland Electronic Navigational Chart(IENC) and vessel information but also allows communication between traffic service center and nearby vessels in case of an emergency situation. In order to implement Navigation guiding applications, developing Inland Electronic Navigational Chart was inevitable. Therefore, IENC of Han River, has developed based on measuring the water depth using multi-beam echo sounder system.