• Applied Chemistry for Engineering
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• v.28 no.2
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• pp.186-192
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• 2017

In this study, water in oil (W/O) emulsion fuel was prepared with surfactant mixture of OIMS90 and NP12 by varying ratio of water to bunker-C oil, surfactant concentration and composition, emulsification time, stirring intensity, temperature and mixing time. Diesel engine performance and exhaust emissions were measured and analyzed with prepared emulsified fuel and compared with those measured using bunker Coil. The results indicated that bunker C emulsion fuel stabilized by surfactant mixture of OIMS90 and NP12 is efficient in reducing emissions of particulate matter, $NO_2$, CO, $CO_2$ and $SO_2$. The biggest reduction in exhaust emission was achieved by using emulsion fuel prepared by OIMS90/NP12 = 4 : 6, 500 ppm of total surfactant concentration and 10% water content at $80^{\circ}C$. Boiler efficiency test measured with emulsion fuel showed excellent energy efficiency compared with bunker C oil.

• Journal of Korea Port Economic Association
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• v.25 no.2
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• pp.231-246
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• 2009

The time charterer depends on speed and bunker consumption rate of time chartered vessel because it is related charterers' benefit. It is important role of stipulated speed and daily bunker consumption rate at the Time Charter Party, it is generated any dispute against speed and daily bunker consumption rate deficiency. The case of dispute is a restricted word of stipulated speed and daily bunker consumption rate at Charter Party as "about", "good weather or good weather day", "smooth water", "ocean current" and "without guarantee". It happens a dispute against speed and daily bunker consumption rate because it is not well-educated as a vessel operator regarding Time Charter Party interpretation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.2
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• pp.145-150
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• 2001

A marine bacterium having a high oil-degrading activity was isolated from the coastal water of Yosu, Korea, identified as Pseudomonas sp. and named Pseudomonas sp. BCK-1. The optimal temperature, pH and NaCl concentration for cell growth was $30^{\circ}C$, 7.0 and $3\%$ (w/v), respectively. After cultivation at $30^{\circ}C$, 180 rpm in 250 mL erlenmeyer flask for 72 and 168 hours, $2\%$ (w/v) arabian light crude oil (ACO) and bunker C oil (BCO) which are considered to be hardly biodegradable compounds were degraded $92\%$ (w/w) and $72\%$ (w/w), respectively.

• Journal of Korea Port Economic Association
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• v.29 no.2
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• pp.63-79
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• 2013

The fundamental endeavor of this study is to investigate the asymmetric relationship between bunker price and Baltic Dry-bulk Index (hereafter BDI). Previous investigations employ linear form based analysis between oil price and BDI but we develop nonlinear and asymmetric cointegration method, which is properly able to capture the decreasing and increasing periods differently. The empirical results show there is no relationships in linear model (e.g. Engle and Granger's methods). On the contrary, our estimate reveals there is significant long-run relationship with asymmetric framework, which implies the necessity of nonlinear and asymmetric consideration to the bunker price analysis.

• Journal of Korea Port Economic Association
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• v.34 no.1
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• pp.99-110
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• 2018

This study empirically examines simple methodology to quantify the risk resulted from the uncertainty of bunker price and foreign exchange rate, which cause main resources of the cost in shipping industry during the periods between $1^{st}$ of January 2010 and $31^{st}$ of January 2018. To shed light on the risk measurement in cash flows we tested GBM(Geometric Brownian Motion) frameworks such as the model with conditional heteroskedasticity and jump diffusion process. The main contribution based on empirical results are summarized as following three: first, the risk analysis, which is dependent on a single variable such as freight yield, is extended to analyze the effects of multiple factors such as bunker price and exchange rate return volatility. Second, at the individual firm level, the need for risk management in bunker price and exchange rate is presented as cash flow. Finally, based on the scale of the risk presented by the analysis results, the shipping companies are required that there is a need to consider what is appropriate as a means of risk management.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.2
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• pp.19-27
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• 2016

Maritime transport is now regarded as one of the main contributors to global climate change by virtue of its $CO_2$ emissions. Meanwhile, slow steaming, i.e., slower ship speed, has become a common practice in the maritime industry so as to lower $CO_2$ emissions and reduce bunker fuel consumption. The practice raised various operational decision issues in terms of shipping companies: how much ship speed is, how much to bunker the fuel, and at which port to bunker. In this context, this study addresses an operation problem in a shipping companies, which is the problem of determining the ship speed, bunkering ports, and bunkering amount at the ports over a given ship route to minimize the bunker fuel and ship time costs as well as the carbon tax which is a regulatory measure aiming at reducing $CO_2$ emissions. The ship time cost is included in the problem because slow steaming increases transit times, which implies increased in-transit inventory costs in terms of shippers. We formulate the problem as a nonlinear lot-sizing model and suggest a Lagrangian heuristic to solve the problem. The performance of the heuristic algorithm is evaluated using the data obtained from reliable sources. Although the problem is an operational problem, the heuristic algorithm is used to address various strategic issues facing shipping companies, including the effects of bunker prices, carbon taxes, and ship time costs on the ship speed, bunkering amount and number of bunkering ports. For this, we conduct sensitivity analyses of these factors and finally discuss study findings.

• Microbiology and Biotechnology Letters
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• v.16 no.4
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• pp.270-274
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• 1988

Samples used for the enrichment culture were collected from the sea water of suspected chronic petroleum contamination in the vicinity of Pusan, Chungmu and Ulsan ports, Korea. Alkaline Iysis and agarose gel electrophoresis techniques were employed to screen these isolates for the presence of plasmid DNA. There were n little differences in the percentage of isolates containing plasmids between sampling sites of unpolluted sen water (22％) and polluted son water (25％). Bacterial isolates taken from the Bunker-C oil enriched culture showed significantly more plasmid incidence (29％). About two thirds of strains grown on a variety of hydrocarbons were Gram negative strains of which 33％ contained one or more plasmids. Multiple plasmids were observed in 23％ of the plasmid-carrying strains. Forty one percent of the plasmids detected were estimated to have a mass of 20 kb or more.

• Journal of the Korea Society of Computer and Information
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• v.26 no.10
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• pp.179-184
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• 2021

In this paper, we propose the deep learning-based neural network model to predict bunker price. In the shipping industry, since fuel oil accounts for the largest portion of ship operation costs and its price is highly volatile, so companies can secure market competitiveness by making fuel oil purchasing decisions based on rational and scientific method. In this paper, short-term predictive analysis of HSFO 380CST in Singapore is conducted by using three recurrent neural network models like RNN, LSTM, and GRU. As a result, first, the forecasting performance of RNN models is better than LSTM and GRUs using long-term memory, and thus the predictive contribution of long-term information is low. Second, since the predictive performance of recurrent neural network models is superior to the previous studies using econometric models, it is confirmed that the recurrent neural network models should consider nonlinear properties of bunker price. The result of this paper will be helpful to improve the decision quality of bunker purchasing.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.3
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• pp.269-277
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• 2019

Since 2020, according to the International Convention for the Prevention of Pollution from Ships (MARPOL) amended in 2016, each Administration shall transfer the annual fuel consumption of its registered ships of 5,000 gross tonnage and above to the International Maritime Organization (IMO) after verifying them. The Administration needs stacks of materials, which must not be manipulated by ship companies, including the Engine log book and also bears an administrative burden to verify them by May every year. This study considers using the Automatic Identification System (AIS), mandatory navigational equipment, as an objective and efficient tool among several verification methods. Calculating fuel consumption using a ship's speed in AIS information based on the theory of a relationship between ship speed and fuel consumption was reported in several examples of relevant literature. After pre-filtering by excluding AIS records which had speed errors from the raw data of five domestic cargo vessels, fuel consumptions calculated using Excel software were compared to actual bunker consumptions presented by ship companies. The former consumptions ranged from 96 to 123 percent of the actual bunker consumptions. The difference between two consumptions could be narrowed to within 20 percent if the fuel consumptions for boilers were deducted from the actual bunker consumption. Although further study should be carried out for more accurate calculation methods depending on the burning efficiency of the engine, the propulsion efficiency of the ship, displacement and sea conditions, this method of calculating annual fuel consumption according to the difference between two consumptions is considered to be one of the most useful tools to verify bunker consumption.

• Journal of Drive and Control
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• v.18 no.4
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• pp.19-27
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• 2021

A bunker bed is a type of furniture that efficiently utilizes a narrow indoor space by having a high bed and using the empty space below as a living and storage space. The demand for multi-purpose furniture is increasing due to the recent increase in single-person households and wide-spread shared accommodation. According to the consumer research, one of the major drawbacks of a bunker bed was to get on and off the bed through a ladder or stairs. In order to overcome these problems, it was confirmed that the height adjustment function that can easily adjust the minimum and maximum heights of the bed was necessary. In this study, a height adjustable bunker bed was designed by using a gas spring that generates a repulsive force by the compressed gas inside. The design process consisted of the following three steps: Firstly, the hysteresis characteristics due to a friction and spring constant of a commercial gas spring were confirmed by measuring the repulsive force vs. compressed displacement. Secondly, requirements of the vertical lifting force exerted on the bed against gravity force were derived. Finally, the height-adjustable bed using the four-bar link mechanism was designed with 4 parameters so that the bed weight of 60-70 kgf could be adjusted to 800 mm in height by an affordable initial operation force. The performance was verified through prototype production and the results of vertical displacement and force to move were nearly the same as designed. In addition, an electrically operated height-adjustable bed was also designed with linear actuators and the performance was proved with the prototype.