• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.151.1-151.1
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• 2010

Natural gas hydrates (NGH) provide 170 gas volumes per unit volume of the medium and are easier to make with moderate pressure and temperature (40 bar at 3 C). Once they form, their preservation temperature is 20 C at 1 bar, which is much milder than the LNG preservation. In case of using the NGH, The small and medium sized gas well has advantages for development because of NGH's these characteristics. According to the cost evaluation report of Gudmundsson in Norway and the research of MES in Japan, the gas well that uses the NGH has a cost saving effect about 10~20% compared LNG. The effect depends on distance and production. However, cost saving and efficiency of liquefaction process is increased by the development of LNG liquefaction technology. Therefore, these factors have to be reflected in economic analysis. The purpose of this research is to compare the cost of Gas Supply Chain according to the transport type, distance and gas reserves. Especially, we consider not only the cost of facility but also the total cost (production cost, transport cost, etc).

• Journal of Navigation and Port Research
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• v.34 no.7
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• pp.587-594
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• 2010

The positive and negative opinion to cargo demand of Incheon's SAMT in the near future remains cloudy. Considering port and shipping environmental changes and the logistics situation of China which explains the lack of facilities in Chinese airports, the creating of SAMT cargoes of the Incheon region could catches a favorable opportunity to be a logistics hub in the North-East Asia. On the other hand, as open-sky policy and direct-call service has been carried out between China and N.A.(North America), Incheon could cause a loss of competitiveness in SAMT because the enhancement in the aspect of the connectivity of Chinese airlines and shipping lines makes customer sent to last destination their cargoes whenever they want. In the same context, this paper analyses on conditions of domestic and international SAMT and proposes in this uncertainty future forecasting of SAMT of Incheon by scenario planning according to changes in integrated SAMT, measuring the likelihood of final scenario. This study shows the Sea & Air multi-transport volume will have either slight increase or decrease from the current condition. Consequently, RFS expansion and system & service improvement through strong ties with major cities in China will be required in a short run aspect. Nonetheless, we also need to take domestic & international transportation environment into account in the long run.

• Ocean and Polar Research
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• v.35 no.1
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• pp.51-61
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• 2013

Two surveys were conducted in January 2006 and September 2007 with multibeam echosounder to investigate the dune shape, migration rate, and bedload transport rate using dune-tracking method on an offshore sand ridge at southern Gyeonggi Bay. The migration rates of dunes range from 1.8 $myr^{-1}$) to 56.0 $myr^{-1}$), at the upper northwestern side of sand ridge towards the southwest direction and from the center of the sand ridge towards the northeast direction respectively. Large (i.e. length 10-100 m) dunes show faster migration (0.3-23.4 $myr^{-1}$) ) than very large (i.e. length > 100 m) dunes because larger dunes have required a larger volume of sediments to be displaced. The decreases in dimensions and migration rates of dunes from the center of sand ridge to the lower part of southeastern side on the sand ridge can be ascribed to the decrease of sandy sediments availability, tidal currents with depth, and the coarsening of surface sediments from the crest of the sand ridge to the trough. Bedload transport rates on the basis of migration rates and dune dimensions decrease from 74.5 $m^2yr^{-1}$) at C transect to 35.6 $m^2yr^{-1}$) at R-02 transect.

• Nuclear Engineering and Technology
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• v.45 no.6
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• pp.707-720
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• 2013

We analyze piecewise homogenization with flux-weighted cross sections and preservation of averaged currents at the boundary of the homogenized domain. Introduction of a set of flux discontinuity ratios (FDR) that preserve reference interface currents leads to preservation of averaged region reaction rates and fluxes. We consider the class of numerical discretizations with one degree of freedom per volume and per surface and prove that when the homogenization and computing meshes are equal there is a unique solution for the FDRs which exactly preserve interface currents. For diffusion submeshing we introduce a Jacobian-Free Newton-Krylov method and for all cases considered obtain an 'exact' numerical solution (eight digits for the interface currents). The homogenization is completed by extending the familiar full assembly homogenization via flux discontinuity factors to the sides of regions laying on the boundary of the piecewise homogenized domain. Finally, for the familiar nodal discretization we numerically find that the FDRs obtained with no submesh (nearly at no cost) can be effectively used for whole-core diffusion calculations with submesh. This is not the case, however, for cell-centered finite differences.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.26 no.2
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• pp.99-103
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• 2020

The volume of parcel delivery is steadily increasing with the rapid growth of the global online e-commerce market. However, a large amount of packaging materials used for these parcel delivery is finally causing environmental problems as waste. In this study, we have taken a pilot test on the returnable parcel delivery packaging & service, which is one of various ways to reduce the generation of the distribution packaging waste raised by e-commerce-based parcel delivery. For the purpose of this project, we made 300 boxes of returnable & foldable delivery packaging(415 mm × 280 mm × 160 mm) and have cooperated with e-commerce company(CJ ENM) & logistics company(LogisAll). Consequently, about 50% of the delivered packages was returned because of the lack of consumer's understanding on the returnable packaging system. We finally have suggested the policy strategy to get over problems derived from the experiment, like the retrieval rate and cost of the returnable packaging, economic efficiency and so on.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.6
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• pp.874-878
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• 2013

Unlike Europe (particularly, Italy and Spain), where a number of studies have been conducted on the stressful effects of transport on rabbit welfare, few studies have been conducted on transportation of rabbits under hot, humid tropical conditions experienced in countries like Malaysia. We studied the effects of transportation in hot humid tropical conditions of Malaysia on physiometabolic changes in New Zealand white rabbits. Eighty experimental animals were divided into two groups of 40 bucks each and transported for either 3 or 1 h. Transportation caused a significant upsurge of aspartate aminotransferase, alanine aminotransferase and creatine kinase activities (p<0.001) though did not significantly affect lactate dehydrogenase (LDH) activity (p = 0.0706). Both transportation periods caused elevation in plasma glucose levels, lactic acidosis and dehydration as evidenced through elevated packed cell volume and plasma protein concentration. It was concluded that regardless of the duration, transport of rabbits under hot humid tropical conditions, resulted in heat distress since the rabbits showed hyperglycemia, hypercalcemia, lactacidemia, lymphocytopenia, dehydration and increase in blood enzyme activities.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.8
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• pp.3121-3135
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• 2015

Owing to the increase in consumption of multimedia content and the improvement of device capacity, user demand for high-quality content has increased. However, it is difficult to transport such large amounts of content over the existing broadcasting network with limited bandwidth. To provide high-definition broadcasting, some studies suggest methods of transporting multimedia over heterogeneous networks after encoding content hierarchically. MPEG Media Transport (MMT), standardized by Moving Picture Experts Group (MPEG), is a solution that enables large-volume media transport over heterogeneous networks such as digital broadcasting networks and packet-switched networks. In the case of delivering a scalable encoded video over different networks, synchronization of each stream is an important issue. MMT defines a synchronization scheme, but does not contain sufficient functions to implement it. In this paper, we propose a synchronization scheme for media streams that are encoded hierarchically, divided into layers, and transported over heterogeneous networks. We implement our scheme using MMT and HTTP, and experimented using three encapsulated video streams with different durations. As a result, we show that the proposed scheme can reduce the waiting time to display high-quality video, relative to Dynamic Adaptive Streaming over HTTP-Scalable Video Coding (DASH-SVC) by requesting segments of enhanced layers after calculating the transmission time. Additionally, we find out that the selection of durations have a relation to the characteristics of the video.

• Proceedings of the Korean Magnestics Society Conference
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• 2013.05a
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• pp.19-20
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• 2013

Thermoelectic properties of the typical thermoelectric host materials, the tellurides and selenides, are known to be noticeably changed by their volume change due to the strain [1]. In the bismuth telluride ($Bi_2Te_3$) crystal, a substitution of rare-earth element by replacing one of the Bi atoms may cause the change of the lattice parameters while remaining the rhombohedral structure of the host material. Using the first-principles approach by the precise full potential linearized augmented plane wave (FLAPW) method [2], we investigated the Ce substitution effect on the thermoelectric transport coefficients for the bismuth telluride, employing Boltzmann's equation in a constant relaxation-time approach fed with the FLAPW wave-functions within the rigid band approximation. Depending on the real process of re-arrangement of atoms in the cell to reach the equilibrium state, $CeBiTe_3$ was found to manifest a metal or a narrow bandgap semiconductor. This feature along with the strong correlation effect originated by the 4f states of Ce affect significantly on the thermoelectric properties. We showed that the position of the strongly localized f-states in energy scale (Fig. 1, f-states are shaded) was found to alter critically the transport properties in this material suggesting an opportunity to improve the thermoelectric efficiency by tuning the external strain which may changing the location of the f-sates.

• Macromolecular Research
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• v.14 no.1
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• pp.101-106
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• 2006

The transport of reactant gas, electrons and protons at the three phase interfaces in the catalytic layers of membrane electrode assemblies (MEAs) in proton exchange, membrane fuel cells (PEMFCs) must be optimized to provide efficient transport to and from the electrochemical reactions in the solid polymer electrolyte. The aim of reducing proton transport loss in the catalytic layer by increasing the volume of the conducting medium can be achieved by filling the voids in the layer with small-sized electrolytes, such as dendrimers. Generation 1.5 and 3.5 polyamidoamine (PAMAM) dendrimer electrolytes are well-controlled, nanometer-sized materials with many peripheral ionic exchange, -COOH groups and were used for this purpose in this study. The electrochemically active surface area of the deposited catalyst material was also investigated using cyclic voltammetry, and by analyzing the Pt-H oxidation peak. The performances of the fuel cells with added PAMAM dendrimers were found to be comparable to that of a fuel cell using MEA, although the Pt utilization was reduced by the adsorption of the dendrimers to the catalytic layer.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2455-2462
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• 2008

Global warming has become one of the most important social responsibilities. After Kyoto protocol for greenhouse gas reduction by climatic change convention came into effect, developed countries are presenting various policies to reduce greenhouse gas that is produced in transport field. One of those policies is modal shift that change from road freight to sea, inland waterway and railway transportation that is eco-friendly. Because increase of road freight brings about road congestion and accident, logistics cost, air pollution and green house gases. Railways are superior to all other modes of transport in mass transportability, high speed, timeliness, safety and environmental-friendliness, but the railway industry has been pushed behind in competition. In developed country's government actively promoted relevant legislation, policies, and countermeasures known as modal shift policies to shift freight transport from road to large volume mode such as railway and ship. In this paper, we discuss the current situation in modal shift, compare it with cases in other countries EU and Japan, identify problems in Korea, and propose the following ways to enhance competitiveness of rail freight.