• Journal of Korean Association for Spatial Structures
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• v.11 no.2
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• pp.129-138
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• 2011

Construction methods for underground structure are classified as bottom-up, up-up, and top-down methods depending on the procedure of construction related to a superstructure. In top-down construction methods, building's main structure is built from the ground level downwards by sequentially alternating ground excavation and structure construction. In the mean time, the main structure is also used as supporting structure for earth-retaining wall, which results in the increased stability of the earth-retaining wall due to the minimized deformation in adjacent structures and surrounding grounds. In addition, the method makes it easy to secure a field for construction work in the downtown area by using each floor slabs as working spaces. However top-down construction method is often avoided since an excavation under the slab has low efficiency and difficult environment for work, and high cost compared with earth anchor method. This paper proposes a combined construction method where semi-open cut is selected as excavation work, slurry as earth -retaining wall and CWS as top-down construction method. In the case study targeted for an actual construction project, the proposed method is compared with existing top-down construction method in terms of economic feasibility, construction period and work efficiency. The proposed construction method results in increased work efficiency in the transportation of earth and sand, and steel frame erection, better quality management in PHD construction, and reduced construction period.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.263-271
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• 2005

The most important point when we engage on waterway dredging work is supplying safe navigational passage to the vessels underway by narrowing dredge work area and removing submerged dangers. In order to meet this end it is neccessary to use auxiliary equipment for shifting actively and mooring and adopt automation of dredging work by integrating information on real time position, dredging depth, and work information. The danger with a spud control system in this study, by the way, is able to employed on continuous dredging work with the narrowest working area allowing wide and safe passages to vessels underway, by moving the dredger to the working zone with the spud controlled automatically. Furthermore, it has been improved definitely compared with the existing dredging proccess management system such that it shows the track of spud and working depth on the electronic navigation chart of window, together with the final outcome of dredging work. The test dredging work at the entrance of Busan North Port for system evaluation showed that actual working time available was twice of the one by the existing anchor system, and that it reduced 38% of time for preparation work and one man power.

• Journal of Navigation and Port Research
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• v.42 no.3
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• pp.151-158
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• 2018

Students from the Maritime universities enrolled themselves into one year navigational training, according to The International Convention on Standards of Training, Certification and Watchkeeping for Seafarer(STCW). The purpose of this paper is to analyze if the students demonstrate improvements and accomplishments while they participate in their practical training. The subjects are third year students of the Korea Maritime and Ocean University who were onboard the Training Ship of the University. The purpose of this paper is to cover the degree of improvement by training, based on the core competency of officers. We also present the basic data for the efficiency in the curriculum of the practical training course for the school. As a result of the research, most of the students showed high improvements in their core competency subjects at the end of their one-year training. However, subjects such as cargo management and protection of the maritime environment resulted in below average results. These were some of the areas that needed improvement.

• Journal of Navigation and Port Research
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• v.44 no.4
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• pp.291-297
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• 2020

In recent years, an increase in deaths and injuries of port cargo handling workers, has raised the need for more effective accident management. The purpose of this study was to evaluate the accident risk for port cargo handling workers and assess ports with high accident risk within the Korean alternative ports using the Entropy & GRA (Grey Relational Analysis). To achieve this purpose, first, 11 Korean ports were selected and the evaluative factors for their outranking evaluation by brainstorming were extracted. Second, the Grey Relational Coefficient of 11 alternative ports was calculated using the GRA. This paper, finally, determined the priority orders of accident risk through calculation of the Grey Relational Grade as the link Grey Relational Coefficient method and the weights of the evaluative factors were calculated by using the Entropy method. In the proposed model, eight criteria such as cargo worker, old cargo worker, work hours, facilities environment, steel cargo volumes, cargo volumes, injury numbers, and death numbers were collected. Busan port was identified as highest accident risk port, and so it should be a top priority to develop a plan to mitigate the risk.

• Journal of Navigation and Port Research
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• v.44 no.4
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• pp.347-353
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• 2020

Aids to Navigation (AtoN) contribute to preventing marine accidents and protecting marine environment by providing various information such as location information etc. to ships. Recognizing the importance of the AtoN, a 24 won of the AtoN service fee is charged for ships entering and leaving international trade ports. However, while the 24 won of the AtoN service fee has been maintained since its establishment in 1999, the demand for new roles of the AtoN service for autonomous shipping and smart port operations, etc. has gradually increasing with the change of shipping and port 4.0. Thus the purpose of this study was to estimate the appropriate level of the AtoN service fee in accordance with such changes in the shipping and port industries. To accomplish this, a method of recovering the total cost was introduced to the PROOF (Pyeongtaek Regional Office of Ocean and Fisheries). It is estimated that there are four cases in which estimation of the AtoN service fee is estimated in two cases year by year and conversion year, the AtoNs of PROOF are classified into the all and part of a ship using the trade port. As a result of the estimation, the AtoN service fee of PROOF is estimated at 53.78-71.62 won (as of 2019), and 29.78-47.62 won is higher than the today at 24 won. The results of this study can be used as useful basic data for the operation of budgets and policy management considering the role of the AtoN.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.20 no.3
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• pp.71-76
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• 2014

Master packaging system is a technology combining primary and secondary packaging to preserve the fresh produce in the supply chain. Master packaging system with tailor-designed gas transfer and $CO_2$ absorber of $Ca(OH)_2$ was applied to fresh shiitake mushroom in its supply from farm to retail store. The temperature, humidity and package atmosphere were monitored through the distribution and/or storage until the packages were opened to measure the mushroom quality. Conventional perforated individual packages without secondary master pack were prepared and travelled the same path for comparison purpose. While high temperature history was observed in some initial period of actual practice of the mushroom transportation and storage unexpectedly, the package atmosphere around the produce in the master packaging system was maintained at modified atmosphere consisting of $O_2$ concentration of 0.4 to 4.2% and $CO_2$ concentration of 0.7 to 1.7%, which is known to be beneficial for the mushroom preservation. While curing the mushrooms with precooled drying was effective for quality preservation, positive effect of master packaging system could be apparent for the uncured mushroom. Harmonized combination of curing treatment, master packaging system and temperature management was suggested for the best quality preservation of the fresh shiitake mushroom.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.4
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• pp.401-417
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• 2020

As an increasing demand for rapid railway transportation, the construction of sidetrack is inevitable to operate local and express trains simultaneously. However, the current technologies for the sidetrack construction method require a long construction period by interrupting the operation of the existing subway line, as well as cause a huge economic loss. Thus, it is necessary to study the sidetrack construction method under the special situation that the subway is in operation and to analyze the risk of the existing tunnel enlargement process for the sidetrack construction. Therefore, in this paper, the Government Complex Gwacheon station on Subway Line 4 was considered as a target station for the virtual sidetrack construction and the optimal sidetrack construction plan was derived. Subsequently, the application of risk management process was carried out in the order of identifying risk, risk response planning, performing a risk analysis, risk monitoring and control for potential risk events during the construction of sidetrack under the subway operation. A total of eight potential risk events and risk mitigation methods were selected, and a risk assessment matrix was established using the five-step risk probability and impact level criteria to perform the risk assessment including residual risks. Based on the results of the risk assessment, the risk grade and the reduction effect of each risk mitigation method were confirmed.

• Journal of Korea Port Economic Association
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• v.23 no.4
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• pp.71-90
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• 2007

To induce container cargos to Gunsan port, we should struggle on securing the quantity of goods transported from the competitive Jeonbuk and Chungcheong areas by reducing transportation expenses by land, and make an activating plan for the international exchange between Gunsan port and nearby ports in China. As a result, if the plan to induce container cargos to Gunsan port is activated, the regular liners will stop at Gusan port. So the new sea route will be opened so that consignors can ship cargos in the proper time. The consignors will use Gunsan port frequently because of the reduction of distribution expenses. To do so, for the first, many incentives should be implemented to attract container cargos. In addition, various facilities should be fully equipped and improved. This paper is to improve the problems for which consignors, the shipping lines and forwarders may feel uncomfortable when they use Gunsan port. According to the research on the actual condition, the biggest problem in Gunsan port is the depth of water. The management, relation system, infrastructure and information system of Gunsan port are also insufficient. Therefore, this paper will make an alternative plan to improve these problems and help the container cargos induce to Gunsan port.

• Journal of Korea Port Economic Association
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• v.30 no.3
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• pp.209-230
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• 2014

The purpose of this study is to have a main change of korea logistics industry analysis and take in the whole situation and the characteristics about a logistics firms. In korean logistics industry, The rate of a carriage is among the low-level as compared with the increasingly high prices for diesel. besides, a national logistics cost and the sales in the transportation industry has increased steadily. On the other hand, the number of trucks and transfer companies has decreased steadily. This change is attributed to expansion of logistics firm size through the limit on a raise in the number of trucks and introduction of a direct consignment system. But medium and small logistics firm size is dwindling in numbers. In the meantime, 2PL since early 2000s has rapidly rose as powerful players in logistics industry by a strong Support of the parent companies. Government and academia have long noted the limit and problems of 2PL system and emphasize on the necessity of activating the 3PL system. So this study divided broadly into two groups that the primary characteristics of korea logistics industry are 2PL and 3PL. Through the results of this study, the management and financial perspectives mean that there is a considerable difference between 2PL and 3PL.

• Journal of Digital Convergence
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• v.18 no.5
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• pp.179-186
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• 2020

The purposes of this paper were: 1) to identify the structural changes of the northeast Asia airport network caused by the pandemic of COVID-19 using social network analysis (SNA) and 2) to suggest proposals for improving airport competitiveness. In this respect, the entire international air routes in northeast Asia airport collected data of 4-10 March 2019 and 9-15 March 2020 through schedules analyzer database of OAG. We found that both the density and centrality have decreased since the spread of COVID-19. The government and airport authorities need active support such as a reduction of various fees and a moratorium on transportation rights to overcome the crisis in the air transport industry. When the COVID-19 situation calms down in the future, we hope that further research will be conducted to identify the structural changes in the SNA aspects through the vast data establishment in countries such as the EU and America.