• KSBB Journal
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• v.24 no.2
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• pp.140-148
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• 2009

The microbial biosurfactants can be substituted to the chemical detergents in some industrial processes. In this study we developed a biotechnological processes for the biosurfactants with microorganisms. The biosurfactants have a lot of advantages in comparision with the chemical surfactants. They are proenvironmental even during and after industrial use. But there are not so many kinds of biosurfactants. The production cost and the end price is much higher than the chemical surfactants. But nowdays there are many kinds of microorganisms, which can produce the surfactants in large quantity and fast. We tried to develop a production process for the large scale with some microorganisms. At first Candida bombicola KCTC 7145, Sphingomonas chungbukensis KCTC 2955 and Sphingomonas yanoikuyae KCTC 2818 are cultivated and studied. For the large scale production process we used molasses as a complex medium and tried to optimize the process. Molasses contains 17 to 25% of water, 45 to 50% of sugar and 25% of carbohydrate, it can be fully used as a substrate. The microorganisms have been cultivated in the diluted media with molasses 2, 5, 8 and 10%, respectively, The optimal conditions for the cultivation and the production process have been studied. For the study the optical density, glucose concentration and the surface tension were measured. Candida bombicola KCTC 7145 and the 5% molasses media was selected as an optimal condition for the production process of a biosurfactant. During cultivation of Candida bombicola KCTC 7145 in the 5% molasses medium kerosene and corn oil were added for promoting the biosurfactants.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.399-404
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• 2015

The cost of fuel in ships has recently increased due to a rapid increase in international oil prices and international restrictions regarding the greenhouse effect generated from the burning of fuel. Therefore, different methods for changing the hull designs for improving energy efficiency, developing coating for reducing friction resistances, developing additives for improving engine thermal efficiency, and low-speed operation for reducing fuel consumption have been considered. The developments of high-speed, large-scale, and energy-saving vessels are deemed essential to adapt to the recent high oil price era. Therefore, it is important to analyze Precisely the qualitative and quantitative changes in the resistance value of the local areas of the hull surface. In this study, the engine performance before and after docking was analyzed to examine friction resistance caused by marine growth on the hull as a basic study for improving the energy efficiency. The result was then presented by comparing it with the previous data for 2.5 years between docks to investigate the performance of the main engine, the change in friction resistances and loads, the fuel consumption and ship speed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.189-197
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• 2011

In the field of structural test, it is a very important factor to apply with an appropriate test jig to enhance test accuracy and efficiency. Especially in the large scale structure test, proper test apparatus scheme will reduce overall cost and time of the test project. Actuators, oil jack and UTM is generally used to evaluate the flexural capacity of the test beam. But in the case of multiple loading point or asymmetric loading of large scale test specimen, existing test method such as UTM have a difficulty in giving an accurate load. In this study new test method which is composed of existing test apparatus will be developed to improve test accuracy and economic efficiency.

• Applied Chemistry for Engineering
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• v.27 no.2
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• pp.171-178
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• 2016

Extensive efforts from all over the world have been made to solve energy problems, such as high oil prices, global warning due to the depletion of oil. Among them, biofuel has been drawing attention as a clean energy, which can replace fossil fuels. However, conventional biofuels were often converted from eatable biomass such as sugar cane, corn and soy which should be replaced with uneatable biomass. In this study, a techno-economical evaluation of the gasification of biomass waste with mixed alcohol synthesis process was performed. Considering available domestic biomass wastes, a 2000 ton/day conversion plant were assumed to produce 533000 L/day ethanol. Also, financial data from previous studies were evaluated and used and economical sensitivities with various operation conditions were established. Economic analysis were conducted by the payback period and internal rate of return (IRR) and net present value (NPV). Sensitivity analyses of raw material costs, initial investment, the major process cost, ethanol price changes and operating costs were all performed.

• Membrane Journal
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• v.31 no.5
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• pp.304-314
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• 2021

Climate change results in unusual weather pattern and affects annual rain fall severely. At the same time, growing industrialization leads to higher energy demand and leakage from petrochemical industry and tanker leads to water pollution. In this scenario, finding out solution to generate clean water is highly essential. For oil/water separation, there are several methods available such as chemical precipitation and adsorption but membrane separation technique is considered to be a more cost and energy efficient process. Amphiphilicity nature of membrane are enhanced by making composite membrane with 2D material such as MXene, resulting in good electrical conductivity and hydrophilicity. This review is mainly classified into two sections: pure MXene and modified MXene. A variety of polymer is used to prepare composite membranes and MXene is modified to further enhance the properties suitable for particular applications.

• Korean Journal of Agricultural Science
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• v.49 no.3
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• pp.397-405
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• 2022

Castor oil cake is widely used as a raw material for organic fertilizers (OF) in Korea. Compared to other fertilizer raw materials, it is highly dependent on imports. In terms of replacing raw materials, dehydrated food waste powder (FDP) and castor oil cake have similar nutritional content, and if 30% is replaced, about 20% of the raw material cost can be saved. However, few studies on the effects on crop growth and soil properties when organic fertilizer and dry food waste powder are mixed and applied to the soil have been reported. The effects of an organic fertilizer made by mixing the commercial available organic fertilizer with dehydrated food waste (OF + FDP) on soil properties and the growth of two types of leafy vegetables (lettuce and young radish) were evaluated and compared with the performance of OF. The fresh weights of lettuce and young radish were the highest with OF amendment and stood at 114.3 and 119.0 g·plant^-1, respectively. These were followed by OF + FDP amendment, which produced 103.1 and 109.6 g·plant^-1, respectively. Compared to the control, OF and OF + FDP increased the lettuce fresh weights by about 69% and 52%, respectively, while the fresh weights of the radish were increased by about 223% and 207%, respectively. The soil pH, EC, total carbon content, and organic matter content in OF and OF + FDP increased. The mixture of dehydrated food waste powder and organic fertilizers is expected to improve soil quality and facilitate stable production of crops and contribute to the substitution of imported organic fertilizer raw materials.

• Ocean and Polar Research
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• v.34 no.4
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• pp.365-384
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• 2012

Microalgae are photosynthetic microorganisms that are highly productive in the presence of basic renewable natural sources (light, $CO_2$, water and nutrients). They can synthesize lipids, carbohydrates and proteins in a small number of days. Subsequently, these carbon-captured products can be processed into both biofuels and valuable co-products. Additionally, microalgae would be an ideal feedstock for replacing land-based food crops with cellular products as high energy density transportation fuels. These microscopic organisms could contribute a significant amount of renewable energy on a global scale. In Korea, microalgae biofuel research was common in the early 1990s. The research activities were unfortunately stopped due to limited governmental funds and low petroleum prices. Interest in algal biofuels in Korea has been growing recently due to an increased concern over oil prices, energy security, greenhouse gas emissions, and the potential for other biofuel feedstock to compete for limited agricultural resources. The high productivity of microalgae suggests that much of the Korean transportation fuel requirements can be met by biofuels at a production cost competitive with the increasing cost of petroleum seen in early 2008. At this time, the development of microlalgal biomass production technology remains in its infancy. This study reviewed microalgae culture systems and biomass production, harvesting, oil extraction, conversion, and technoeconomical bottlenecks. Many technical and economic barriers to using microalgal biofuels need to be overcome before mass production of microalgal-derived fuel substitutes is possible. However, serious efforts to overcome these barriers could become a large-scale commercial reality. Overall, this study provides a brief overview of the past few decades of global microalgal research.

• Journal of Animal Science and Technology
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• v.58 no.8
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• pp.30.1-30.12
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• 2016

Background: The effect of choline chloride supplementation through forced drinking combined with concentrate diets containing Ca-fish oil on milk production and milk composition of Etawah Grade goats was evaluated. Choline chloride is an essential component in ruminant diets as it is required for fat metabolism. Method: The experiment was conducted in a completely randomized block design with three types of treatments and eight replications. The trial had two successive experimental periods; the first, during the eight weeks of late pregnancy, and the second, during the first 12 weeks of lactation. Twenty-four Etawah Grade does in the second gestation period were divided into three treatment groups. Commercial choline chloride 60 % in corncobs-based powder was used as a source of choline chloride. The treatments were no supplementation (control) and supplemented with either 4 g or 8 g/2days of choline chloride. Choline chloride was given to the animals through a forced drinking technique, after dissolving it in 60 ml drinking water. The initial body weight of does was $38.81{\pm}3.66kg$. The does were penned individually, and were given fresh chopped King Grass ad libitum and 700 g/day of concentrate diets containing Ca-fish oil, starting eight weeks prior to expecting kidding and continuing for 12 weeks of parturition. Results: All nutrient intakes were not significantly different (p > 0.05) among the treatments during the late pregnancy and the lactation periods. Supplementation did not affect (p > 0.05) the average daily gains and feed conversion ratio during pregnancy but gave effects (p < 0.05) on the average daily gains, feed conversion ratio and income over feed cost during lactation. The highest average daily milk yields and 4 % fat corrected milk yields were found in goats supplemented with 4 g/2days of choline chloride and increased by 17.00 % and 24.67 %, respectively, compared to the control. Moreover, milk composition percentage and milk constituent yields improved significantly (p < 0.05) in those supplemented with 4 g/2days of choline chloride. Conclusion: The supplementation of 4 g/2days of choline chloride through forced drinking increased milk yields, the 4 % fat corrected milk yields, milk composition, milk constituent yields, and improved feed conversion ratio and income over feed cost of Etawah Grade goats.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.4
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• pp.294-303
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• 2008

Squid jigging fishery is very important in that there are about 1,000 jigging vessels more than 10 tonnage and about 5,000 ones less than 10 tonnage in Korea. But the cost of oil which is used to light fishing lamps, goes significantly up to almost one hundred million won for 50 tonnage vessels and forty million won in case of vessels less than 10 tonnage. This cost has almost taken 40% of total fishing costs. That is, the fishing business condition of squid jigging fishery is recently in the very difficult situation. As oil price increases, the business condition of the fishery gets worse and worse. Therefore it is very urgent to develop an economical fishing lamp, to solve this problem of fishery's business difficulty. This research aims at developing a fishing lamp for squid jigging fishery using the light emitting diode which has very excellent efficiency and durability. We made a water tank with 20 meters width which is a shape of raceway to research behavioral characteristics of Japanese flying squid to LED light, and made an experiment to investigate optimum wave of LED light to lure squid. The method is to establish LED lamps on both ends of water tank and to observe squid's behavior. Colors and wave lengths of LED lamps, used in experiment, are red(634nm), yellow(596nm), green(523nm), blue(454nm) and white(454nm+560nm). In experiment for attractive capability of LED lamp to squids, Japanese flying squid are highly attracted to blue lamp and white lamp. However, they are dispersed to red and yellow lamps. In addition, Japanese flying squid have moved and stayed in both dark ends of water tank. When compared intermittent lamp with continuous lamp, Japanese flying squid are highly attracted to intermittent lamp when intermittent interval is 0.25 second.

• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.537-542
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• 1999

Removal of sulfur compounds in the petroleum products is essential for the prevention of sulfur oxides. However, conventional methods involving catalytic reactions are found to have some limitations in complete removal of harmful sulfur compounds and to require relatively high cost. Recently, desulfurization process using microorganisms is known to be promising in terms of excellent sulfur removal efficiency and reasonably low treatment cost. For the biodesulfurization process to be effective, the solubilization of sulfur compounds into aqueous solution is a prerequisite. In this study, polyoxyethylene nonionic surfactants were used in order to enhance the solubilization of sulfur spectrophotometer. The solubilization of sulfur compounds was found to increase with temperature and to bo abruptly increased at above 1 wt % surfactant solutions. It was also observed that the longer the hydrophobic chain of the surfactant molecule, the higher solubilizing power of a nonionic surfactant. It was found that the Tergitol series surfactants showed higher solubilizing capacity than Neodol series presumably due to the disruption of the regular packing in the hydrocarbon region of the surfactant aggregates.