• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.04a
• /
• pp.77-82
• /
• 2004

Quantifying rates of microbial processes under subsurface conditions is difficult, and is most commonly approximated by laboratory studies using aquifer materials. In this study a single-well, 'push-pull' test method is adapted for the in situ determination of denitrification rates in groundwater aquifers. The rates of stepwise reduction of nitrate to nitrite, nitrous oxide, and molecular nitrogen were determined by performing a series of push-pull tests at an experimental well field of Korea University. A single Transport Test, one Biostimulation Test, and four Activity Tests were conducted for this study. Transport tests are conducted to evaluate the mobility of solutes used in subsequent tests. These included bromide (a conservative tracer), fumarate (a carbon and/or source), and nitrate (an electron acceptor). At this site, extraction phase breakthrough curves for all solutes were similar, indicating apparent conservative transport of the solutes prior to biostimulation. Biostimulation tests were conducted to stimulate the activity of indigenous heterotrophic denitrifyinc microorganisms. Biostimulation was detected by the simultaneous production of carbon dioxide and nitrite after each injection. Activity tests were conducted to quantify rates of nitrate, nitrite, and nitrous oxide reduction. Estimated zero-order degradation rates decreased in the order nitrate '||'&'||'gt; nitrite '||'&'||'gt; nitrous oxide. The series of push-pull tests developed and field tested in this study should prove useful for conducting rapid, low-cost feasibi1ity assessments for in situ denitrification in nitrate-contaminated aquifers.

• Journal of the Korean Society for Railway
• /
• v.16 no.1
• /
• pp.59-64
• /
• 2013

This study analyzed passenger access and egress travel patterns related to a Korean regional railway station (Seoul station), then developed a binomial logit model. This model referred to bus and metro mode of access and egress during a national holiday (Chuseok 2009); obtained from transit smart card data. The results showed that 99% of passengers getting access to, or egress from, the regional railway station did so using less than two transfers, and that most passengers were more likely to choose a metro. However, the passengers that made access or egress trips near Seoul Station were more likely to take a bus. From the results of the mode choice model, it was found that the impact of travel time was greater than that of travel cost, in the choices made for both access and egress. Interestingly, the impact of travel time is much greater in choosing the mode of egress.

• Journal of Navigation and Port Research
• /
• v.29 no.8 s.104
• /
• pp.709-714
• /
• 2005

The purpose of this research is to verify the strategic fitness and relevance of the hub port strategy by SCM in Northeast Asia and to find a method to be a hub-port with a competitive edge. The fitness of the hub port development strategy is analysed by the structural equation model. The essential results of the research show that minimizing lead time from arrival of ship to inland transport and maximizing logistic services of each stage are important to provide optimal logistic service. And value-added port supply chain strategy is highly co-related with all the parts of port operation system, port transport system, distribution park and port information system. It shows that: various value added logistic service activity is more important than lowing cost; inland multimodal system should be rightly connected; distribution park should be connected to industry park to be a port cluster; and port information system should be developed.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.51 no.3
• /
• pp.333-339
• /
• 2015

Fish exportation using airplanes incurs sizable logistics costs (12,000KRW/kg), according for more than 45% out of the total export cost. Thus, it is unreasonable to quantitatively expand fish exportation by means of air transport. In addition, cases of failing to deliver fish at the right time to the right place occurs frequently due to the limited cargo capacity and insufficient cargo space of airplanes, especially during the peak season. Therefor, a technology that not only minimizes the logistics costs but also transports fish freshly and safely, in the case of long distance exportation to countries such as the United States and Taiwan, should be developed. In this study, a live fish container control system for long distance transportation was designed and implemented. Live flatfish (2,000kg) were selected as the target fish, were transported to the United States to analyze and verify the performance of the a live fish container control ystem and transportation ability.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.04a
• /
• pp.188-191
• /
• 2003

Sing]e-well-push-pull tests were developed for use in assessing the feasibility of in-situ aerobic cometabolism of chlorinated aliphatic hydrocarbons (CAHs). The series includes Transport tests, Biostimulation tests, and Activity tests. Transport tests are conducted to evaluate the mobility of solutes used in subsequent tests. These included bromide or chloride (conservative tracers), propane (growth substrate), ethylene, propylene (CAH surrogates), dissolved oxygen (electron acceptor) and nitrate (a minor nutrient). Tests were conducted at an experimental well field of Oregon State University. At this site, extraction phase breakthrough curves for all solutes were similar, indicating apparent conservative transport of the dissolved gases and nitrate prior to biostimulation. Biostimulation tests were conducted to stimulate propane-utilizing activity of indigenous microorganisms and consisted of sequential injections of site groundwater containing dissolved propane and oxygen. Biostimulation was detected by the increase in rates of propane and oxygen utilization after each injection. Activity tests were conducted to quantify rates of substrate utilization and to confirm that CAH-transforming activity had been stimulated. In particular, the transformation of injected CAH surrogates ethylene and propylene to the cometabolic byproducts ethylene oxide and propylene oxide provided evidence that activity of the monooxygenase enzyme system, responsible for aerobic cometabolic transformations of CAHs had been stimulated. Estimated zero-order transformation rates decreased in the order propane > ethylene > propylene. The series of push-pu3l tests developed and field tested in this study should prove useful for conducting rapid, low-cost feasibility assessments for in situ aerobic cometabolism of CAHs.

• Journal of the Korean Institute of Navigation
• /
• v.18 no.2
• /
• pp.91-109
• /
• 1994

Technological and organisational changes in transport system have introduced new dimension into port system development and inter-port competition. The quality of service now required by the customer is costly and not easily provided by small shipping companies and small ports. It has been suggested that in the future container shipping may be concentrated by space-sharing arrangements or actual mergers into the hands of a few mega-operators with the investment potential to provide total logistics networks. In order to compete effectively, high load factors will be essential and port concentration inevitable. A fa-voured few ports will become the load centres and other ports will assume a secondary feeder role. In this study, three questions are raised and attempts are made to answer them : (a) what is the new role of ports today ; (b) why should ports be engaged in this new role ; and (c) how can ports play this new role. In short, a modern port should be a service centre and a logistic platform for international trade and transport-a third generation port. Ports, in particular, have to make every effort to be competitive in the cost and quality of services and to make the port a transport and distribution service centre. For most ports, this is not an option but a must ; an essential requirement for survival in this win or lose situation. The best way to win is to maintain a close contact with port users, listen to them, discuss with them, help them and satisfy them. That is port marketing. Starting from the findings of port marketing, it is es-sential to work out appropriate development plans and marketing targets and to improve port competitive-ness. As an alternative method, a port competitiveness model is suggested, which may help port managers to make appropriate improvements.

• Journal of the Korean Society for Railway
• /
• v.18 no.5
• /
• pp.471-480
• /
• 2015

Reliance on road transport in domestic logistics can lead to intensified congestion and greenhouse gas emissions due to the rise in oil prices, any increase in logistics costs can have a high social cost. The government policy on Low Carbon Green Growth is seeking to take advantage of the railway system. However, existing railway transport logistics systems, for reasons such as low speed, low track capacity constraints, and the impossibility of implementing a Door to Door system, make it difficult to activate a railway logistics program. As a result of this study, a national R&D project to develop a High-Speed Passenger/Baggage Mixed Train(Hy-SoBex) utilizing the rail capacity constraints to overcome the difficulties of linking an air cargo and freight railway logistics system, we propose a variety of service models and select the optimal service model.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.10
• /
• pp.1317-1327
• /
• 2016

The baggage handling system (BHS) is one of the most complex system in the airport. A highly economical operating system is required to ensure its performance in consideration of its enormous cost on the extension. Furthermore, the inefficient operation deteriorates not only the system performance but the imbalance among the check-in counters because of a bottleneck on the conveyors downstream. The objective of this research is to improve the performance of both the BHS and the check-in area by efficiently controlling the flow in the merging area on the conveyors. Thus, we suggest a control logic of which the concept is borrowed from data networks. The simulation is used to analyze impacts of the conveyors bottleneck on the check-in area and optimize some parameters used in the suggested logic. We also discuss some observations from the simulation results into several aspects of performance measures.

• Journal of Navigation and Port Research
• /
• v.41 no.5
• /
• pp.353-358
• /
• 2017

This study aims to propose an assessment tool of port service quality (PSQ) in the context of container transport logistics (CTLs), by taking the perspectives from port users. The CTLs defined in this study are the relevant activities of serving the physical flows of a container box from a point of origin via a container port to a point of destination. To address the ports' role in collaboration between its channel members in CTLs, the PSQ measures for all port user groups (i.e. common PSQ measures) are selected based on the relevant CTLs activities involved by port, and its users within terminal/port area as well as throughout the CTLs chain. An importance-performance analysis (IPA) is applied as a diagnostic tool to analyse the status quo of Busan Port in CTLs contexts, by comparing the importance and performance (IP ) scores against each individual CTLs criterion. The findings from the IPA reveal that port managers and policy makers at the Busan Port should concentrate on six PSQ measures (i.e. SR1, SR4, ITS1, VAS1, VAS4, ICI3) to enhance PSQ in CTLs. However, four measures (i.e. ITS2, ITS3, ITS4, VAS2) are identified as a possible overkill, indicating an area of inefficiency where a remedial action of the cost-cutting decision is necessary. On the other hand, the Busan port shows an outstanding performance on four measures such as SR2, SR3, ICI1 and ICI2. The measures are not only important but also high performance. The study findings provide managerial guidance to port managers in Busan Port, in view of searching for managerial and operational strategies for sustainable port growth.

• Journal of the Korean Society for Railway
• /
• v.15 no.3
• /
• pp.272-277
• /
• 2012

KORAIL's logistics business coefficient is improved slightly from 197.4 in 2009 to 190.7 in 2010 but the cost is still high compared to the revenues. In order to derive activities for the efficient logistics and measure their effects quantitatively, the analysis of various indexes that can be extracted from the statistical data is very important. In this study, the various indexes are analyzed to evaluate the efficiency of freight cars based on railway logistics. It can be used to estimate the various activities for the efficient logistics associated with freight cars. We suggest the Indexes as the number of transport, cumulative transport distance and transport income to evaluate the efficiency of freight cars and they should be applied according to the characteristics of each index.