• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.7
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• pp.1067-1073
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• 2021

Regulations to reduce greenhouse gas emissions from ships are gradually being strengthened. EEXI (Energy Efficiency Existing Index) has been introduced in existing ships, and various studies are aimed at achieving the greenhouse gas emission reduction target are currently underway. In this study, we proposed a method to reduce greenhouse gas emissions through reducing fuel oil consumption by applying a solar power generation system to a pure and truck carrier among existing ships engaged in international voyages. The proposed photovoltaic power generation system consists of a photovoltaic module, an energy storage system, and a power conversion device. To confirm applicability, the system was modeled through a power electronics program, and a simulation was performed. In addition, economic analysis was conducted to check the feasibility of application to real ships, and it was confirmed that significant results were derived in the economical aspect after about 11 years had elapsed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.4
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• pp.302-307
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• 2001

The underwater background noise measured in Geoje and Tongyoung diving fishing ground from May to December, 2000 and analyzed to get optimum carrier frequency and transmitter power level for underwater wireless telephone design. The results obtained are summarized as follows: 1. At the Geoje and Tongyoung diving fishing ground, the lowest ambient noise band was 25~30kHz with 57dB and 52dB re 1$\mu$Pa, respectively. 2. At the Geoje and Tongyoung diving fishing ground, the lowest noise band during fishing activity was 67dB and 62dB re 1$\mu$Pa, respectively. 3. At the Geoje diving fishing ground, the noise of water jetter which is a digging machine for subbottom shells was 102dB re 1$\mu$Pa. 4. Considering the design parameters of underwater wireless telephone, it is found that the optimum carrier frequency band is around 30kHz and the transmitter source level should be at least 131dB re 1$\mu$Pa for 500m range telephone.

• Information Systems Review
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• v.10 no.3
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• pp.21-38
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• 2008

After the introduction stage, Korean mobile game market is approaching to the growing stage leading mobile contents market. The environment for the mobile contents business is getting better by the expansion of the 3G mobile networks and the enhancement of the mobile devices. In this research, at a content level, not a service level, market success factors of mobile games and the differences by genres and their changes over time were investigated through the analysis of the real market data of mobile games launched by a Korean mobile carrier. The most important factors for market success, especially for the genres of RPG/Tycoon/Simulation and Shooting/Action/Arcade, were found to be the 'design' factor and its effect turned to be getting stronger as time goes by after the launch. Consumers' purchase rate was actually higher for the mobile games of popular genres or in relation with socially popular subject matters. Also 'design' and 'creativity' factors which are related to the quality of contents, have gotten more important over time. One of the most interesting results was that there existed a "blue ocean" genres like Sports/Racing/Leisure which had a steady demand but not many competing games. In the analysis of the 'convenience' factor, one interesting implication for mobile game producers was that there exists a trade off between the ease of initial adoption and the steady sales of a mobile game.

• Journal of Distribution Science
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• v.12 no.2
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• pp.27-37
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• 2014

Purpose - As economic activities between different countries have rapidly spread in a world of free trade, it is inevitable that a large volume of cargo will be carried between countries. It is natural, then, that CO2 emissions and other environmental pollutions have followed, which exposes people and society to serious environmental problems and social costs, and so on. Therefore, the need to understand logistics is not only a matter of transportation but also an environmentally oriented matter. The purpose of this study is to look at some lessons and implications from the European case in terms of green logistics matters. Research design, data, and methodology - In order to look into this matter, first, it has to be established that some cargo transport volumes using different transportation modes have clearly declined because of previous economic recessions. Some transport policies produced by the European Union (EU) are based in a long history of struggling to cope with transport matters in European countries. In its recent transport policies, the EU has provided greener transportation alternatives, realizing that pollution matters affect the European transport market. This study tries to determine what policies the EU has implemented to deal with green logistics matters. This study concentrates in particular on the Marco Polo program in the EU. Results - This study found that the EU seems to consider these kinds of matters, that is, transport and the environment in the context of green logistics. The EU launched some policy instruments to solve this matter relatively earlier than other countries and reviewed them as necessary. In order to make these policy tools work, the EU provided PACT for combined transport, and then the Marco Polo I and II European transport white paper packages. These European policies deal with green logistics matters in two ways. First, some restrictions have been imposed, especially taxation, and so on. Transport subsidies are also powerful means of handling green logistics matters in Europe. Along with these two means of dealing with transport and the environment, the EU eventually targeted integration of different transport modes. Instead of employing only a single transport instrument mode to deliver the cargo to be carried, such as trucking, rail, ocean-going carrier, flight, or inland waterway transport, the EU has proposed that combining transport modes is the best alternative for transport and the environment. That is, the EU is pursuing the adoption of multimodalism as an answer to the green logistics challenge as it provides a more cost efficient and more productive means of transport. Conclusions - In conclusion, multimodal transport should be considered when applying green logistics, as it can provide an alternative way to achieve transport and environmental solutions together at the present time. Two methods can be used to encourage multimodal transport: restrictions and subsidies. These are the lessons and implications from European green logistics policies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.262-267
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• 2017

The number of shops needed for the fabrication of a sphere type cargo tank for an LNG carrier is proportional to the size of the tank to be constructed. Due to the limitations of facility investment, it is difficult to fabricate various size tanks with a perfectly spherical shape in the (factory). An efficient method of increasing the capacity of the cargo tank is to extend the conventional sphere type LNG tank vertically by inserting a cylindrical shell structure. In this study, equations for the dynamic pressure distribution due to horizontal acceleration are derived for a sphere type LNG tank with central extension. The derived equations can be easily applied to the design and structural assessment of a sphere type LNG tank with central extension. Furthermore, the results of this study can be combined with the static design loads previously reported by Shin & Ko [9], in order to establish a simplified analysis method which enables a precise initial estimate to be obtained, thereby obviating the need for a time consuming finite element analysis.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.4
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• pp.353-365
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• 2020

The quantitative increase in maritime transport for domestic and foreign trade is one of the main reasons for the increase in marine pollution accidents. Despite the implementation of relevant laws in each country to prevent and mitigate marine pollution accidents caused by ships, human negligence (carelessness, intention, etc.) by ship workers has been reported as the biggest cause of marine pollution accidents. One of the most effective ways to reduce marine pollution accidents caused by ships is to reduce human negligence through systematic education and training of ship workers. Therefore, this study aimed to review the appropriateness of the statutory education and training curriculum for ship marine pollution prevention managers in accordance with domestic laws and regulations such as the 「Marine Environment Management Act」 and suggest improvement measures. To this end, we compared and analyzed the legal training·general education courses related to the prevention of marine pollution and marine disasters in Japan, where the laws and systems are similar to Korea, and investigated the cases of legal training for experts in land pollution prevention in Korea.

• Strategy21
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• s.46
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• pp.159-204
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• 2020

This study is written to bring the proposal forward for the direction of south korean naval force. The political situation and the circumstance of the world, especially in the area of Pacific Ocean, are changing very rapidly. North Korea has been always the conventional existing intimidator for South Korea since the 6·25-War. Additionally, the strengthening movements of the national defense, which is easily noticed from China and Russia, is also an other part of intimidating countries against South Korea. Those three mentioned countries are continually developing the asymmetrical warfare systems, for example a strategic nuclear weapon. Since the Obama Administration, the Asia-Pacific Rebalancing-Strategy has been changed as an East Asian foreign policy. Nowadays, Trump Administration renamed the 'United States Pacific-Command' to 'United States Indo-Pacific Command'. The purpose of this is not only letting India to participate in american alliance, but also reducing an economic burden, which is often mentioned in USA. West Germany was located in the very similar geopolitical position during the Cold War just like South Korea these days. And that's why the strategy of West German Navy is worthy of notice for south korean naval force to decide its suitable strategy. Most of all, the two most important things to refer to this study are the plan to expand naval air force and the realistic political stand for us to take it. In conclusion, I laid an emphasis on maintenance of 'green-water-navy'. instead of selecting the strategy as a 'blue-water-navy'. The reason I would like to say, is that south korean navy is not available to hold the unnecessary war potential, just like Aircraft-Carrier. However, this is not meaning to let the expansion of naval force carelessly. We must search the best solution in order to maintain the firm peace within the situation. To fulfill this concept, it is mostly very important to maintain the stream of laying down a keel of destroyers, submarines and air-defense-missile, as well as the hight-tech software system, taking a survey of 4th industrial revolution. Research and development for the best solution of future aircraft by south korean navy is likewise necessary. Besides, we must also set the international diplomatic flexibly. As well as maintaining the relationship with US Forces, it is also very important to improve the relationship with other potential allied nation.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.539-545
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• 2018

In recent years, research on shipping market forecasting with the employment of non-linear AI models has attracted significant interest. In previous studies, input variables were selected with reference to past papers or by relying on the intuitions of the researchers. This paper attempts to address this issue by applying the stepwise regression model and the random forest model to the Cape-size bulk carrier market. The Cape market was selected due to the simplicity of its supply and demand structure. The preliminary selection of the determinants resulted in 16 variables. In the next stage, 8 features from the stepwise regression model and 10 features from the random forest model were screened as important determinants. The chosen variables were used to test both models. Based on the analysis of the models, it was observed that the random forest model outperforms the stepwise regression model. This research is significant because it provides a scientific basis which can be used to find the determinants in shipping market forecasting, and utilize a machine-learning model in the process. The results of this research can be used to enhance the decisions of chartering desks by offering a guideline for market analysis.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.546-554
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• 2018

The Bulk market, unlike the line market, is characterized by stiff competition where certain ship or freight owners have no influence on freight rates. However, freights are subject to macroeconomic variables and economic external shock which should be considered in determining management or chartering decisions. According to the results analyzed by use of ARIMA Inventiom model, the impact of the financial crisis was found to have a very strong bearing on the BDI index. First, according to the results of the VEC model, the libor rate affects the BDI index negatively (-) while exchange rate affects the BDI index by positively (+). Secondly, according to the results of the VEC model's J ohanson test, the order ship volume affects the BDI index by negatively (-) while China's economic growth rate affects the BDI index by positively (+). This shows that the shipping company has moved away from the simple carrier and responded appropriately to changes in macroeconomic variables (economic fluctuations, interest rates and exchange rates). It is believed that the shipping companies should be more aggressive in its "trading" management strategy in order to prevent any unfortunate situation such as the Hanjin Shipping incident.

• New Physics: Sae Mulli
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• v.68 no.12
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• pp.1315-1323
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• 2018

We studied the carbonization due to the annealing condition of waste coffee powder for application as an active anode material for lithium-ion batteries (LIBs). The coffee powder used as an active anode material for LIBs was obtained from coffee beans, not from a coffee shells. The waste coffee powder was dried in air and heat-treated in an $Ar/H_2$ atmosphere to obtain a pore-forming activated carbon powder. The specific capacity of the sample annealed at $700^{\circ}C$ was still 303 mAh/g after 1000 cycles at a current density of 1000 mA/g and with a coulombic efficiency of over 99.5%. The number of pores and the pore size of the waste coffee powder were increased due to chemical treatment with KOH, which had the some effect as an increased specific surface area. The waste coffee powder is considered to be a very promising active anode material because of both its excellent electrochemical properties due to enhanced carrier conduction and its being a cost effective resource for use in LIBs.