• Journal of Navigation and Port Research
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• v.28 no.8
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• pp.709-714
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• 2004

This paper first tries to analyze total sea transport costs for the transshipment in Busan Port in comparison with direct transport to 4 Chinese Ports, Dalian, Tinajin, Qingdao and Shanghai, based on vessel operation scenarios. The results found that the transshipment in Busan port for the 4 Chinese ports are more expensive than the direct calling to the 4 ports, which implies that Busan port needs to make compensation as an incentive to the carriers providing transshipment service to it in order to keep their royalty. For the compensation, it suggested a method of calculating the Container Terminal Facilities Leasing Fee to levy additional revenue by port authority.

• Macromolecular Research
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• v.17 no.10
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• pp.729-733
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• 2009

Solution casting films of sulfonated poly[styrene-b-(ethylene-r-butylene)-b-styrene] copolymer (sSEBS)-based composite membranes that contained different amounts of organic, nanorod-shaped polyrotaxane were annealed at various temperatures for 1 h. The films' properties were characterized with respect to their use as polymer electrolyte membranes in direct methanol fuel cells (DMFCs). Different aspect ratios of polyrotaxane were prepared using the inclusion-complex reaction between $\alpha$-cyclodextrin and poly(ethylene glycol). The presence of the organic polyrotaxane inside the membrane changed the morphology during the membrane preparation and reduced the transport of methanol. The conductivity and methanol permeability of the composite membranes decreased with increasing polyrotaxane content, while the annealing temperature increased. All of the sSEBS-based, polyrotaxane composite membranes annealed at $140^{\circ}C$ showed a higher selectivity parameter, suggesting their potential usage for DMFCs.

• International Journal of Automotive Technology
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• v.6 no.6
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• pp.571-577
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• 2005

Combustion of turbulent sprays in a direct injection diesel engine is modeled by the conditional moment closure (CMC) model. The CMC routines are combined with the KIVA code to provide conditional flame structures to determine mean state variables, instead of mean reaction rates. An independent transport equation is solved for each flame group with equal mass of sequentially evaporating fuel vapor. CMC calculation begins as the fuel mass for each flame group begins to evaporate with corresponding initialization conditions. Comparison is made with measured pressure traces for four operating conditions at different rpm's and injection conditions. Results show that the CMC model with multiple flame histories can successfully be applied to ignition and mixing-controlled combustion phases of a diesel engine.

• Journal of Mechanical Science and Technology
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• v.18 no.4
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• pp.597-605
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• 2004

Turbulent temperature field in a channel subject to strong wall injection has been investigated via direct numerical simulation technique. These flows are pertinent to internal flows inside hybrid rocket motors. A simplified model problem where a regression process at the propellant surface is idealized by wall injection has been investigated to understand how the temperature field is modified. The effect of strong wall injection displaces thermal boundary layer away from the wall and this causes a sharp drop of friction temperature. Turbulent diffusivity and dissipation time scale for temperature field are found to show large variations in the streamwise direction under application of wall blowing. It is, thus, expected that more sophisticated turbulence models would be required to predict the disturbed temperature field accurately.

• Macromolecular Research
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• v.14 no.2
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• pp.214-219
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• 2006

Cast Nafion-based composite membranes containing different amounts of organic, nanorod-shaped polyrotaxane were prepared and characterized, with the aim of improving the properties of polymer electrolyte membranes for direct methanol fuel cell applications. Polyrotaxane was prepared using the inclusion-complex reaction between ${\alpha}$-cyclodextrin and poly(ethylene glycol) (PEG) of different molecular weights. The addition of polyrotaxane to Nafion changed the morphology and reduced the crystallinity. The conductivity of the composite membranes increased with increasing polyrotaxane content up to 5 wt%, but then decreased at higher polyrotaxane contents. Well-dispersed, organic polyrotaxane inside the membrane can provide a tortuous path for the transport of methanol, as the methanol permeability depends on the aspect ratio of polyrotaxane, which is controlled by the molecular weight of PEG. All of the Nafion-based, polyrotaxane composite membranes showed a higher selectivity parameter than the commercial Nafion films did.

• Membrane and Water Treatment
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• v.7 no.1
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• pp.71-86
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• 2016

The present study deals with a numerical simulation for the transport phenomena in three configurations of Membrane Distillation (Air Gap, Direct Contact and Sweeping Gas Membrane Distillation) usually used for desalination in order to make an objective comparison between them under the same operating conditions. The models are based on the conservation equations for the mass, momentum, energy and species within the feed saline and cooling solutions as well as on the mass and energy balances on the membrane sides. The theoretical model was validated with available data and was found in good agreement. DCMD configuration provided the highest pure water production while SGMD shows the highest thermal efficiency. Process parameters' impact on each configuration are also presented and discussed.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.5
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• pp.708-726
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• 2018

In this study, we examined the contribution of nitrogen oxides and volatile organic compounds emitted from China and Japan to ozone concentrations over Gwangyang-bay, South Korea. We used a chemical transport model, Community Multi-scale Air Quality model, and its instrumented sensitivity tool, High-order Decoupled Direct Method. Intercontinental Chemical Transport Experiment-Phase B 2006 for East Asia and Clean Air Policy Support System 2007 emissions inventories for South Korea were used for the ozone simulation. During the study period, May 2007, the modeled maximum daily 8-hr average ozone concentration among seven air quality monitors in Gwangyang-bay was 68.8 ppb. The contribution of $NO_x$ emissions from China was 19.5 ppb (28%). The highest modeled ozone concentrations and Chinese contributions appeared when air parcels were originated from Shanghai area. The observed 8-hr average ozone concentrations in Gwangyang Bay exceeded the national ambient air quality standard (60 ppb) 203 times by daytime and 56 times by nighttime during the period. It was noticed that many exeedances happened when contribution of Chinese emissions to ozone concentrations over the area increased. Sensitivity analysis shows that a reduction in Chinese $NO_x$ and VOC emissions by 15% could lessen the total exceedance hours by 24%. This result indicates that high ozone concentrations over Gwangyang-bay are strongly enhanced by Chinese emissions.

• Journal of the Korean association of regional geographers
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• v.21 no.3
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• pp.503-514
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• 2015

This study aims to analyze the relationship between transport infrastructure investment and rural development in Korea in a more systematic and empirical way. To do so, we formulate research framework to examine the multi-faceted relationship through extensive literature review and carry out a descriptive study on the spatial patterns of road investment and rural development in Korea. Finally, using the structural equation model, this study carries out the exploratory empirical analysis on the direct and indirect relationship between transport infrastructure investment and rural development. The study finds that the transport infrastructure investment in rural Korea impacts clearly on both the population base promotion and production and income growth through better accessibility. In addition, the investment has an indirect effects on the production and income growth through its influence on the population base promotion. This implies that the transport infrastructure investment in rural Korea so far exerts both long-term and short-term influences on rural development through various channels of impacts.

• Journal of Nutrition and Health
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• v.33 no.6
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• pp.660-667
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• 2000

Previous studies on the effect of age on intestinal taurine transport in animals have invariably shown a decline in the activity of the transport system with increasing age. In the present study changes in taurine transporter activity were observed during cell differentiation in the human colon carcinoma cell line HT-29 This cell line exhibits various enterocytic characteristics when differentiated and therefore has frequently been used to study the characteristcs and regulation of nutrient and drug absorption in the small intestine at the cellular level. Pre-treatment of the cells with $\beta$-alanine(10mM) reduced the taurine transport activity to 33% of the value for the control cells(p<0.05) which implies that taurine and $\beta$-alanine share a common $\beta$-amino acid transport system for their celluar uptake in the HI-29 was continued until 21 days post seeding. Kinetic studies of the taurine transporter were conducted in the HT-29 cell line with varying taurine concentration(5-60$\mu$M) in the uptake medium Both Vmax and the Michaelis-Menten constant(Km) of taurine transporter were decreased as differentiation of the HT-29 cell line was progressed ; Vmax of the taurine transporter in cells incubated for 4, 14 and 21 days post seeding was 2.79$\pm$3.4m 16.89$\pm$1.74, and 0.85$\pm$0.08 and 0.32$\pm$0.01nmol.mg protein-1 .30min-1 respectively(p<0.001) and Km was 42.3$\pm$3.4, 16.89$\pm$1.74, and 11.2$\pm$3.0$\mu$M respectively (p<0.01) These results indicate that the activity of sodium dependent active taurine transport system in the HT-29 cell line is decreased as confluent cells are differentiated. This phenomenon in cell culture system corresponds well with the earlier observation of lower intestinal taurine transport activity in suckling rats compared to that in adult animals although direct relationship of cell differentiation with in vivo aging process needs further verification.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.1
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• pp.37-44
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• 2009

Density is the most important congestion indicator among the three fundamental flow variables, flow, speed and density. Measuring density in the field has two different ways, direct and indirect. Taking photos with wide views is one of direct ways, which is not widely used because of its cost and lacking of proper positions. Another direct density measuring method using two spot detectors has been introduced with the concept of instantaneous density, average density and measurement interval. The relationship between accuracy and measurement interval has been investigated using the simulation data produced by Paramics API function. Finally, density measurement algorithm has been suggested including exponential smoothing for device development.