• Journal of Navigation and Port Research
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• v.30 no.3 s.109
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• pp.173-179
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• 2006

A number of perforated plates are utilized for the passage of the crew and the equipment, reducing weight and the arrangement of piping. Hull girders in double bottom and floor plates are the typical parts which have those plates in a ship structure, and the perforated plate is usually positioned at the place which has less loading without local strength problems. In the case of utilizing the plate inevitably at the place which has large strength, an opening of the plate has large effect on the buckling strength due to in-plane rigidity and ultimate strength. Therefore the assessments of the elastic buckling strength and the ultimate strength for the perforated plate are the essential requirements for determining the dimensions of the parts at the initial design stage. With above reason, a need of the reasonable assessments for the elastic buckling strength and the ultimate strength has evolved. The numerical series analysis with the consideration of the effect due to various aspect ratios and slenderness ratios were performed using finite element method in this research. Simple formulas for the design are also proposed from the above analysis.

• Journal of Navigation and Port Research
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• v.43 no.1
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• pp.72-78
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• 2019

The second-hand ship market provides immediate access to the freight market for shipping investors. When introducing second-hand vessels, the precise estimate of the price is crucial to the decision-making process because it directly affects the burden of capital cost to investors in the future. Previous studies on the second-hand market have mainly focused on the market efficiency. The number of papers on the estimation of second-hand vessel values is very limited. This study proposes an artificial neural network model that has not been attempted in previous studies. Six factors, freight, new-building price, orderbook, scrap price, age and vessel size, that affect the second-hand ship price were identified through literature review. The employed data is 366 real trading records of Panamax second-hand vessels reported to Clarkson between January 2016 and December 2018. Statistical filtering was carried out through correlation analysis and stepwise regression analysis, and three parameters, which are freight, age and size, were selected. Ten-fold cross validation was used to estimate the hyper-parameters of the artificial neural network model. The result of this study confirmed that the performance of the artificial neural network model is better than that of simple stepwise regression analysis. The application of the statistical verification process and artificial neural network model differentiates this paper from others. In addition, it is expected that a scientific model that satisfies both statistical rationality and accuracy of the results will make a contribution to real-life practices.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.7
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• pp.1169-1178
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• 2022

This study examines an effective operational plan of a maritime safety enforcement task that is distributed in the Ministry of Oceans and Fisheries and the Korea Coast Guard for maritime safety. Considering the sinking of the MV Sewol and Seohae vessels and the MV Hebei Spirit oil spill, normally marine safety accidents tend to not only damage human life, property, and marine environment but can also expand to disasters; therefore, precautionary measures are required. However, the Korean government takes superficial efforts in case of large-scale accidents. In case of the MV Sewol ferry, the government only focused on punishing the officials involved as a follow up and never mentioned any effective plan, such as "unification of maritime safety enforcement," in contrast to an advanced country. As a result, there are endless major and minor backward accidents. The probability of large-scale maritime accidents and backwardness accidents is increasing owing to vessels becoming large sized, high speed, and aged; sailors being unqualified; port traffic increase, development of marine leisure; and inefficiency dual marine safety systems. Therefore, based on the review of previous studies related to maritime safety, major advanced country's cases, and unified case of the vessel traffic service, this study suggests effective methods such as coastal vessel safety management, port state control and aid to navigation management, which are directly connected with maritime safety.

• Journal of Navigation and Port Research
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• v.47 no.1
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• pp.18-24
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• 2023

After the Great East Japan Earthquake, many reports and books that compiled testimonies of adult victims were published. Thus, refugee situations are well known, but information on the refugee situations of Japanese students is not. This is because what actions the students took and how they sought refuge from an earthquake or tsunami have not been fully recognized. The purpose of this study was to examine and analyze students' refuge behavior in the Great East Japan Earthquake and to predict the refuge behavior of students affected by future disasters. The results of the study showed that students passively acquired information about earthquakes and tsunamis and that their refuge behavior was highly dependent on adults. Immediately after an earthquake, people tended to protect themselves and stay in place until the shaking stopped. However, they tended to move to another place after the shaking occurred frequently. Students living on ria coastlines were likely to move to high places to escape the threat of earthquakes and tsunamis, whereas students living in plain regions were likely to move vertically to tall buildings, such as schools. As for the mode of movement to refugee shelters, the students arrived at the final refugee shelters in one move, and it is assumed that the refugee shelters should be decided in advance and the students should move there.

• Science of Emotion and Sensibility
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• v.7 no.4
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• pp.35-41
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• 2004

This study addressed the development of an automobile aroma blast device to reduce fatigue of drivers. We also analyzed the adaptation character of the aroma blast device, The aroma blast device was designed in a way that volatilized aroma is mixed with oxygen (air) and blasted to the outside, It was devised to possibly change on/off time of 2-Port Solenoid Valve using the 8051 micro processor, through which the amount of aroma can be controlled, We conducted an experiment to examine time for occurrence/elimination of adaptation to aroma in 20 college students using 4 types of natural fragrances, The subjects had an average age of 22$\pm$2 years and included both men and women. The results showed that the occurrence and elimination times for adaptation to aroma were 1 minute 28 seconds and 3 minutes and 15 seconds for Jasmine 30%, 2 minutes and 41 seconds and 4 minutes and 3 seconds for Jasmine 50%, 1 minute and 47 seconds and 2 minutes and 59 seconds for Peppermint 30%, and 1 minute 59 seconds and 4 minutes and 11 seconds for Peppermint 50%, respectively.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.269-274
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• 2004

The marine electronic system for safe navigation such as ECDIS has been contributing to increase the safety of navigation, decreasing the mariner's load of navigation. The ECDIS should be developed and approved by international standard of IMO for performance standard and IEC for type-approval method and required results. However, these standards have some ambiguities for us not to directly adopt them for real approval system, so we should analyze them for more clear meaning and prepare our own detail standard for type-approval system. The first thing to do for the goal of this research was to analyze the standard in detail and make ambiguity be cleared in our own standards, considering each test item in view of test methodology. For the result of analysis we could develop more evident and detail type-approval standard for each test item with test technology needed. Especially, we developed the colour differentiation test process of ECDIS monitor, which include the colour differentiation formula derived from CIE colour scheme. Several test items require sensor informations of navigation equipment compatible with IEC 61162. We also developed the signal simulator for general messages of IEC 61162 that must be provided. Additionally, the type-approval processes and standards for Back-up arrangement and RCDS mode were developed.

• Journal of Navigation and Port Research
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• v.28 no.1
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• pp.1-8
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• 2004

The final goal of this research is to establish the relative dangerousness D/B for factors on seakeeping performance. This D/B is, essential to develope the seakeeping performance evaluation system built-on-ship. The system is composed of the apparatus for measuring a vertical acceleration to be generated by the ship's motions, computer for calculating the synthetic seakeeping performance index and monitor for displaying the evaluating diagram of navigational safety of ship. In this paper, a methodology on the establishment of the relative dangerousness D/B for factors on seakeeping performance is presented by a numerical simulations, playing an important role on the algorithm of the program for calculating the synthetic seakeeping performance index. Finally, It is investigated whether the relative dangerousness D/B can be realized an accurate values according to the loading conditions, weather conditions, wave directions and present ship's speed of a model ship.

• Journal of Navigation and Port Research
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• v.39 no.1
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• pp.7-13
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• 2015

The number of mobile terminals equipped with a GPS module is steadily increasing today. However, because they using code pseudorange measurements in positioning, the positioning accuracy of mobile terminals is lower than that of those receivers using carrier phases. Especially, the multipath signal causes more significant errors in code pseudoranges. Therefore, the techniques of multipath detection and elimination is necessary. In this study, as an initial analysis of multipath detection and elimination technique development, we tested the feasibility of multipath signal detection using GPS signal strength information. We found that the GPS signal strength increases as the elevation angle gets higher in the open-sky environment. Also, we found that the signal strength decreases when there were some signal reflectors nearby. We checked the repeatability of the signal strength variation characteristics by reflecting repeat time of GPS satellites. As a result, this characteristics repeats almost perfectly when GPS satellites pass the same orbit. Therefore, we found that it is not a temporary phenomenon and the multipath signal detection should be possible by using GPS signal strength information.

• Journal of Navigation and Port Research
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• v.38 no.3
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• pp.247-252
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• 2014

Despite the facts that navigation technology and educational programs were developed, and that maritime law has been enforced strictly, the number of maritime accidents has not dropped significantly. Accident prevention is emphasized because of the extreme life, property, and environmental losses that accompany maritime accidents. Even though there are a variety of preventive activities, their performance is not satisfactory. In order to promote preventive activities and to organize safety management, a Preventive Index of Ship Accident(PISA) and a Preventive Level of Ship Accident(PLSA) which are abstracted from the statistical data of ship accidents (2009~2013) are proposed. The survey module by which these variables can be calculated is composed of preventive domains such as education, engineering, enforcement and information, and is applied for the preventive indexes measurement of cargo, passenger, tanker, tugboat and fishery ships. We compared and analyzed measured result with statistical accident rates and cases to confirm the index utilities. It was found that there is some correlation between the index value and the ship accident rate. It is expected that this index will become useful to evaluate a preventive status for the prevention of ship accidents and for the maritime safety culture.

• Journal of Korea Port Economic Association
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• v.28 no.1
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• pp.143-157
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• 2012

By strengthening the market control and expanding the networks, providers of global logistics are expanding their service scope. The warehouses connect networks to internal and external warehouses by using logistics providers. The paper focuses on analyzing the efficiency of warehouses on each district. Therefore, the study classifies the factors which specify the efficiency of a total logistics of warehouse industry and warehouses' employees and the number of warehouses on district. Furthermore, the most recently published reports by National Center for Statistics in 2012 was used in order to guarantee credibility of the study. This study utilizes five years of materials, which are from 2005 to 2009. By applying SBM (Slack Based Measure), DEA Window model, and the Malmquist productivity model, the trend in efficiency and stableness were analyzed. The principal purpose of the paper is evaluating the efficiency. Also, analyzing its determinants and illustrating a long-term relationship between the regional warehouses and annual turnover of the warehouses were used as output measures. In addition, the number of warehouses of each region, employees, warehouses equipments, and the Logistics Warehouses Providers were used as input measurements. As a result, Malmquist productivity model and annual stableness has shown a continuous increasing. Ultimately, to be approved as product of Korea, a new stratiges that meet the standards and Rules of Origins by FTA should be developed. Therefore, there must be a development that takes regional characteristics into consideration.