• Membrane Journal
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• v.28 no.2
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• pp.136-141
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• 2018

Carbon dioxide ($CO_2$) exists not only as a component of natural gas, biogas, and landfill gas, but also as a major combustion product of fossil fuels which leads to a major contributor to greenhouse gases. Hence it is essential to reduce or eliminate carbon dioxide ($CO_2$) in order to obtain high fuel efficiency of internal combustion engine, to prevent corrosion of gas transportation system, and to cope with climate change preemptively. In recent years, there has been a growing interest in not only conventional membrane-based separation but also new adsorbent-based separation technology. Particularly, in the case of metal-organic frameworks (MOFs), it has been received tremendous attentions due to its unique properties (eg : flexibility, gate effect or strong binding site such as open metal sites) which are different from those of typical porous adsorbents. Therefore, in this study, stereotype of two MOFs have been selected as its flexible MOFs (MIL-53) representative and numerous open metal sites MOFs (MOF-74) representative, and compared each other for $CO_2/CH_4$ separation performance. Furthermore, varying and changeable separation performance conditions depending on the temperature, pressure or samples' unique properties are discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.10
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• pp.4717-4737
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• 2017

Today, smart grids, smart homes, smart water networks, and intelligent transportation, are infrastructure systems that connect our world more than we ever thought possible and are associated with a single concept, the Internet of Things (IoT). The number of devices connected to the IoT and hence the number of traffic flow increases continuously, as well as the emergence of new applications. Although cutting-edge hardware technology can be employed to achieve a fast implementation to handle this huge data streams, there will always be a limit on size of traffic supported by a given architecture. However, recent cloud-based big data technologies fortunately offer an ideal environment to handle this issue. Moreover, the ever-increasing high volume of traffic created on demand presents great challenges for flow management. As a solution, flow aggregation decreases the number of flows needed to be processed by the network. The previous works in the literature prove that most of aggregation strategies designed for smart grids aim at optimizing system operation performance. They consider a common identifier to aggregate traffic on each device, having its independent static aggregation policy. In this paper, we propose a dynamic approach to aggregate flows based on traffic characteristics and device preferences. Our algorithm runs on a big data platform to provide an end-to-end network visibility of flows, which performs high-speed and high-volume computations to identify the clusters of similar flows and aggregate massive number of mice flows into a few meta-flows. Compared with existing solutions, our approach dynamically aggregates large number of such small flows into fewer flows, based on traffic characteristics and access node preferences. Using this approach, we alleviate the problem of processing a large amount of micro flows, and also significantly improve the accuracy of meeting the access node QoS demands. We conducted experiments, using a dataset of up to 100,000 flows, and studied the performance of our algorithm analytically. The experimental results are presented to show the promising effectiveness and scalability of our proposed approach.

• Journal of Korea Port Economic Association
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• v.24 no.4
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• pp.71-96
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• 2008

The purpose of this study is to suggest the new strategies for West coast ports, especially Mokpo Port development. This paper also analyzes the recently evolving change of shipping environment such as upsizing of vessels, horizontal and vertical integration strategies in the liner shipping industries through the mergers and acquisitions or strategic alliances, establishment of dedicated terminal and surging bunker charge. With shipping environment is rapidly changing, we examine how to cope with the current situation and suggest the solutions how to tackle shippers' and shipping companies' request. As a result of an empirical study, we found out that Mokpo Port suffers from the shortage of container cargo, container imbalance, insufficient forwarders and inland trucking service providers and hinterland transportation network system. With these obstacles settled, the number of container cargo can be induced to Mokpo Port and the regular container services between Mokpo and Chinese ports and Japanese ports loops were found to be competitive.

• Archives of design research
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• v.13 no.3
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• pp.59-68
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• 2000

This thesis is about design spirit demanded by the 21st century vehicle design studied in consideration of city commuter. First of all, going over the transition of the last century vehicle design led to the arrangement of the changes in vehicle models. Even though the invention of vehicles brought about immense improvement in living standard of the people, it also brought about other factors that were harmful for human living. Through this realization the main fact that should be emphasized is that the vehicles in 21s1 century should not be a threat to the human life or be the main cause for the environmental pollution of the earth. With the question as to whether the vehicles development direction at the beginning of the year 2000 like the Retro design and Hybrid-Compact car development is appropriate to these demands, the development of City Commuter vehicle (the most human and environment-friendly concept which can also serve as the connecting means in transportation system) and its case studies were compared. Through this, the design spirit that should be inherent in environment and vehicle human and vehicle relationships and the design factors needed for the continuous development of the vehicles were arranged.(classified) Rather than suggesting a new direction for the specific style for vehicle design, this thesis is to emphasize that to improve the standard living of the people with vehicle as a product that will be continually produced in the 21st century, the morals and the mission of the designers about the environment and humanity recovery should be the core of the active movement and education of vehicle design.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.1
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• pp.21-30
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• 2017

The surface temperature of disc brakes varies during braking, which can affect the friction and wear behavior of braking systems. In order to develop an efficient braking system, the friction and wear behaviors of brake materials need to be clearly understood. In this work, the friction and wear behavior of the C/C-SiC-Cu composite and the Al/SiC composite, which are used in disc braking systems, were investigated. Both the surface temperature and contact pressure were studied. A pin-on-reciprocating tribotester was used for this purpose, in order to control temperature and load. Results showed that the friction varied significantly with temperature and sliding distance. It was found that a transfer layer of compacted wear debris formed on the wear track of the two materials. These layers caused the surface roughness of the wear track to increase. The outcome of this work is expected to serve as a basis for the development of braking systems under various operating conditions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.4
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• pp.284-291
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• 2017

There is no doubt that advances in UAV technology have improved military performance. However, these advances require humans to adapt to new and complex operational systems. UAV has been rapidly expanding to a variety of fields such as reconnaissance, transportation, communication and aerial photographing recently. Also, with the development of UAV automation technology, one operator is able to supervisory-control multiple-UAVs. However, as the number of assigned UAV increases, the amount of information increases and this results in the workload of the operator increasing and deterioration in controlling performance. Accordingly, there is a need for a model to determine the level of overload an operator may encounter with regard to multiple-UAV but nationally this kind of research is currently lacking. Therefore, this paper provides an experimental platform for evaluating workload index effectiveness integrating multiple-UAV operational environments, GCS, and eye-tracking system followed by a limited survey of domestic and international studies of multi-UAV overload studies.

• Journal of Korea Water Resources Association
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• v.39 no.9 s.170
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• pp.779-786
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• 2006

In this study, we propose a new method that utilizes rainfall data in and out of a basin, which is greater than 25.4mm for point rainfall or 12.7mm for areal mean rainfall respectively. From our analysis, most frequent quartile for point and areal mean rainfall were found to be the same in general for various rainfall duration intervals. From an evaluation of design rainfall per each rainfall duration distributed in time by the MOCT(Ministry of Construction and Transportation) version of Huff's method and this study, peak rainfall intensity by this study was found to be greater than the one by MOCT, but there were no consistent increase or decrease of this difference with rainfall durations. Using the distributed design rainfall per each duration by MOCT and this study, corresponding flood inflow hydrographs were simulated and compared each other. Contrary to the case of peak rainfall intensity, difference in peak flow by both methods per each rainfall duration started to increase from about 12-hr duration. Especially, the difference in peak flow was significant when critical rainfall duration was considered, and this trend was similar for peak flows of other rainfall durations. Therefore, the method proposed in this study is thought to be the effective procedure for the construction of dimensionless cumulative rainfall curve that is representative of a basin while considering time distribution characteristics for different rainfall durations.

• Journal of the Korean Society for Railway
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• v.16 no.1
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• pp.40-46
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• 2013

Based on Korean railway design standards, the thicknesses of the reinforced roadbeds of conventional and high speed railways are different, and so too, for the size distribution of the ballast particles. Accordingly, considerable cost would be required to increase operating speeds of conventional lines, in particular related to changing from a ballasted track system to a ballastless one. In this study, applicability of a roadbed which supports conventional ballasted track, for use as a ballastless track for a high speed rail line was examined. A reinforced roadbed for a conventional railway is 20cm thick, and the type of material used for a conventional reinforced roadbed is M-40 (crushed gravel for road embankments). A dynamics test was conducted to evaluate the occurrence of the permanent settlement of the track substructure. These results suggest that, without changes to the track substructure, an operational speed of 400km/h is feasible with a ballastless track. This result; however, is from laboratory experiments. Further studies, such as numerical analyses or field validation, are required.

• Journal of the Korea Concrete Institute
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• v.28 no.4
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• pp.489-496
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• 2016

Recently, a concern about hollow core precast concrete (PC) slab has been increased as a method to improve the construction ability by reducing the self weight of structures during the construction. Hollow core slab which is known as a typical PC slab in domestic construction of PC building has a problem to put shear reinforcements in the web of element during the production of element in the factory. With regard to this point, recently, tripple ribs slab (TRS) which can be said as a new type of half PC slab system was developed. In TRS, it is possible to place shear reinforcements in PC element during the production of the element in the factory. This paper presents the shear test result of TRS which was done by one point loading test under simple support condition. Test parameters are the presence of cast-in-place (CIP) concrete and the contribution of lattice bars. From the test, it was found that the TRS has sufficient shear capacity to resist the design load and its strength can be predicted by the code equations for general beam. It is recommended to ignore the strength of lattice bar in the calculation of shear strength during the construction since its contribution is too low to be considered when CIP is not casted.

• Spatial Information Research
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• v.20 no.6
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• pp.33-43
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• 2012

As part of recent sustainable transport, bike has come into the spotlight as a green transport at close range to link between walking and public transit and also alterative to solve problems of existing vehicle travel. Some arguments on promotion of using bicycles have already been made in Europe, the U.S and other developed countries. To be sure, much has been written extensively in description of utilization of bike oriented by supplier, for examples, Level of Service with bike path, infrastructure such as bicycle racks and lounge etc. Therefore, our study has been differentiated in development of new evaluation model focused on level of bike user's satisfaction, comprehensively considering suitability for bikeway installation, connectivity of the public transportation system and stability in Incheon City. ANP(Analytic Network Process) analysis which is able to allow consideration of the interdependence of criteria has been hired due to multi-collinearity instead of AHP used in multi-criteria decision analysis. Last but not least, we drew bike route on a case-by-case for maintenance and improvement of its facility in Namdong-gu and Bupyeong-gu. To conclude, suggested finding has dem onstrated the validity of evaluation scheme for bikeways which is appropriate for type and purpose and ultimately this can be used to establish policy decision making for improvement of bikeway.