• Proceedings of the KSR Conference
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• 2005.05a
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• pp.1125-1131
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• 2005

This study is based on the assumption of surface transport linkages between Korea and China. Active economic cooperation between South Korea and North Korea are expected within the near future and Russia and China have interested in the land transport linkages in Korean peninsula. How much freight demands between the two countries that has been mainly dependent on air and sea transportation so far may convert the transport mode to surface transportation are estimated. Particularly, freight demands between South Korea and China's three northeast provinces are focused. The sensitivity analysis depends on transport time and transport cost changes is included. The modal shifts is estimated to be more sensitive to the changes in transport costs than those in transport time, suggesting the importance of transport costs of rail and road. Despite the dearth of data on the surface transport operation in North Korea, the attempts made in this study to estimate the demand conversion are hope to provide reference points for potential effects of the rail and road transport connections between China and the Korea peninsula before our discussions expand to the establishment of freight transport network of the northest Asia and, moreover, the Eurasian continent.

• Journal of Navigation and Port Research
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• v.39 no.5
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• pp.409-415
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• 2015

According to the globalization of world economy on distribution and sales, logistics and transportation parts are playing an important role. Especially, they have to decide what is the key factor of route choice model and how to choose the right transport route in multimodal transport system. By considering the key factors in rote choice model for freight forwarders between Mongolia and Korea, this paper propose 4 main factors: Cost, Delivery time, Freight and Logistics service with 13 sub factors. The importance of factors is surveyed base on AHP through interview with freight forwarders. In results, the empirical insights about current status of Mongolian forwarders are provided with different factors between transportation modes. Expecially, the Time factor is a role factor to choose transport route for air transportation forwarders.

• Journal of the Korean Society for Railway
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• v.16 no.5
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• pp.418-429
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• 2013

This study assesses the appropriate amounts and applicable ranges of travel time values for freight transport modes in Korea. The findings suggest that it is possible to determine appropriate sizes and applicable ranges of travel time values of goods set for road transport mode (i.e. truck), whereas those for railway, inland waterway, marine, and air transport modes are not as easily estimated. The adequate travel time value for trucks is 20,000won/vehicle hour, and the application range of travel time value of trucks is 17,000~23,000won/vehicle hour considering other variables. The most adequate estimation method of determining the travel time value for road transport is the wage rate method, whereas the marginal rate of substitution method is more rational for railway, inland waterway, marine, and air transport modes considering the application purpose and characteristics of the goods transported.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.43-48
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• 2004

RTP that is proposed supplement of real-time services on internet environment, as Real-time Transport Protocol, is the protocol that for the purpose of sending data of stream type. RTP and RTCP(Real-time Transport Control Protocol) basically work at the same time, RTCP serves with state information of network at present. RTP has important properties of a transport protocol that runs on end-to-end systems and provides demultiplexing. It also offer reliability and protocol-defined flow／congestion control that transport protocol like TCP can not provides. In this paper, we look around concept and construction of Differentiated sen1ice tint run on RTP and by setting parameters of packet transfer method be used CBQ(Class-Based Queuing) for packet transfer on Differentiated service, each service queue controls properly through packet scheduling method, such as WRR(Weighted Round Robin) and PRR(Packet-by-packet Round Robin) all service classes do not experience the starvation and confirm the performance through computer simulation to achieve fairly scheduling.

• Journal of applied mathematics & informatics
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• v.11 no.1_2
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• pp.215-241
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• 2003

In this paper, solute transport in heterogeneous aquifers using a modified Fokker-Planck equation (MFPE) is investigated. This newly developed mathematical model is characterised with a time-, scale-dependent dispersivity. A two-dimensional finite volume quadrilateral mesh method (FVQMM) based on a quadrilateral background interpolation mesh is developed for analysing the model. The FVQMM transforms the coupled non-linear partial differential equations into a system of differential equations, which is solved using backward differentiation formulae of order one through five in order to advance the solution in time. Three examples are presented to demonstrate the model verification and utility. Henry's classic benchmark problem is used to show that the MFPE captures significant features of transport phenomena in heterogeneous porous media including enhanced transport of salt in the upper layer due to its parameters that represent the dependence of transport processes on scale and time. The time and scale effects are investigated. Numerical results are compared with published results on the some problems.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.3
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• pp.15-27
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• 2017

In general, increasing train dwell time leads to increasing train service frequency, and it in turn contributes to increasing the congestion level of train and platform. Therefore, the studies on train dwell time have received growing attention in the perspective of scheduling train operation. This study develops a prediction model of train dwell time to enable train operators to mitigate platform congestion by metering passenger inflow at platform gate with respect to platform congestion levels in real-time. To estimate the prediction model, three types of independent variables were applied: number of passengers to get into train, number of passengers to get out of trains, and train weights, which are collectable in real-time. The explanatory power of the estimated model was 0.809, and all of the dependent variables were statistically significant at the 99%. As a result, this model can be available for the basis of on-time train service through platform gate metering, which is a strategy to manage passenger inflow at the platform.

• Advances in environmental research
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• v.5 no.4
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• pp.263-282
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• 2016

Contaminant transport in groundwater induces major threat and harmful effect on the environment; hence, the fate of the contaminant migration in groundwater is seeking a lot of attention. In this paper a two dimensional numerical flow and transport model through saturated layered soil is developed. Groundwater flow and solute transport has been simulated numerically using proposed model. The model implements the finite volume time splitting method to discretize the main equations. The performance, accuracy and efficiency of the out coming numerical models have been successfully examined by two test cases. The verification test cases consist of two-dimensional, groundwater flow and solute transport. The final purpose of this paper is to discuss and compare the shape of contaminant plume in homogeneous and heterogeneous media with different soil properties and control of solute transport using a zone for minimizing the potential of groundwater contamination; furthermore, this model leads to select the effective and optimum remedial strategies for cleaning the contaminated aquifers.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1053-1057
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• 1987

In this paper, we have studied a communication protocol which may provide Audio/Video data transmission in real time. Auido/Video data have its own characteristics. A new transport protocol with realtime constraint has been designed and implemented which performs dynamic error control and flow control depending on the characteristics of transmitted Audio/Video data. Since the receiving data can be predicted from the previously received data using the prediction function in Auido/Video data transmission, these functions are introduced in our transport protocol that may possibly improve the speed of data transmission and give a real time response. We have tested our transport protocol and measured the performance by the simulation. We assume that our transport protocol would be used in LAN environment. Our prime purpose is to provide a reliable and real time Auido/Video data transmission service.

• Biomedical Science Letters
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• v.15 no.1
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• pp.55-60
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• 2009

Insect cells such as Spodoptera frugiperda Clone 9 (Sf9) cells are widely chosen as the host for heterologous expression of a mammalian sugar transport protein using the baculovirus expression system. Characterization of the expressed protein is expected to include assay of its function, including its ability to transport sugars and to bind inhibitory ligands such as cytochalasin B. It is therefore very important first to establish the transport characteristics and other properties of the endogenous sugar transport proteins of the host insect cells. However, very little is known of the transport characteristics of Sf9 cells, although their ability to grow on TC-100 medium strongly suggested the presence of endogenous glucose transport system. In order to investigate the substrate and inhibitor recognition properties of the Sf9 cell transporter, the ability of pentoses to inhibit 2-deoxy-D-glucose (2dGlc) transport was investigated by measuring inhibition constants $(K_i)$. To determine the time period over which of sugar into the Sf cells was linear, the uptake of 2dGlc 0.1mM extracellular concentration was measured over periods ranging from 30 seconds to 30 minutes. The uptake was linear for at least 2 minutes at the concentration, implying that uptake made over a 1 minute time course would reflect initial rates of the sugar uptake. The data have also revealed the existence of a saturable transport system for pentose uptake by the insect cells. The transport was inhibited by D-xylose and D-ribose, although not as effective as hexoses. However, L-xylose had a little effect on 2dGlc transport in the Sf9 cells, indicating that the transport is stereoselective. Unlike the human erythrocyte-type glucose transport system, D-ribose had a somewhat greater apparent affinity for the Sf9 cell transporter than D-xylose. It is therefore concluded that Sf9 cells contain an endogenous sugar transport activity that in some aspects resembled the human erythrocyte-type counterpart, although the Sf9 and human transport systems do differ in their affinity for cytochalasin B.

• IE interfaces
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• v.24 no.4
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• pp.281-294
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• 2011

This paper considers the rail crane scheduling problem which is defined as determining the sequence of loading/unloading container on/from a freight train. The objective is to minimize the weighted sum of the range of order completion time and makespan. The range of order completion time implies the difference between the maximum of completion time and minimum of start time of each customer order consisting of jobs. Makespan refers to the time when all the jobs are completed. In a rail freight terminal, logistics firms as a customer wish to reduce the range of their order completion time. To develop a methodology for the crane scheduling, we formulate the problem as a mixed integer program and develop three metaheuristics, namely, genetic algorithm, simulated annealing, and tabu search. To validate the effectiveness of heuristic algorithms, computational experiments are done based on a set of real life data. Results of the experiments show that heuristic algorithms give good solutions for small-size and large-size problems in terms of solution quality and computation time.