• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1215_1216
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• 2009

Most transformer use insulating and cooling fluids derived from petroleum crude oil, but mineral oil is some possibility of environmental pollution and fire with explosion. vegetable oil fluids extracted from seed has superior biodegradation and fire-resistant properties including an exceptionally high fire point enhancing fire safety. In this study, it is aimed at the practicality of substituting natural ester dielectric fluid for mineral oil in liquid insulation system of transformers. As a rise in coil winding temperature has a direct influence on transformer life time, it is important to evaluate the temperature rise of coil winding in vegetable oil in comparison with mineral oil. Three transformers for the test are designed with 10KVA, 13.2KV, one phase unit. The temperature are directly measured in insulating oil of these transformers with the two sorts of natural ester and mineral oil dielectric fluid respectively. Temperature of vegetable oil transformers was similar to temperature of mineral oil transformer in the same design at 80% load and above.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.4
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• pp.407-411
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• 2011

The technology of line heating has evolved in various methods. Among them, fossil fuels like ethylene gas and LPG(Liquid Petroleum Gas) are widely used due to their simple utility. In the meantime, the technology implementing high frequency for line heating has also been developed continually, but its manufacturing technology or application includes lots of problems by now. One of the main characteristics of line heating using conventional technolob'Y is the quenching effect followed by heating process. On the other hand, hydrox gas which is mixed by hydrogen and oxygen is a prominent candidate for an application without above shortcomings. Especially, it is found that line heating using hydrox gas is tremendously effective taking low cost as well as low noise. In this paper, a small cell with high efficiency which can minimize installing space is developed to deal with the problem installing in narrow place. Experiments to prove the validation, efficiency and effectiveness is carried out by characterizing in the line heating of steel. It is found that the energy saving of using hydrox gas for line heating is significant and that the deviation performance is reduced by 78~89%. Furthermore, the noise is also reduced as amount of 18.3% though the heating time is not too different.

• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1399-1409
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• 2019

Biodiesel is a renewable and environmentally friendly liquid biofuel for transportation. Insect is considered as a new valuable biomass to convert into biodiesel. In particular, BSF(Black Soldier Fly) containing high fat is a renewable source of biodiesel. Biodiesel drived BSF has high concentration of saturated fatty acid methyl ester and low concentration of polyunsaturted fatty acid methyl ester which makes it potentially an ideal substrate for producing excellent quality biodiesel. Most of the fuel properties of BSF biodiesel were met the requirements of standard EN 14214. BSF have a higher lipid yield and biodiesel productivity as compared to microalgae and vegetable oils. This review paper includes the overall summary and compilation of the insect research conducted on biodiesel production and includes the BSF biodiesel properties.

• Advanced Composite Materials
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• v.16 no.4
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• pp.269-282
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• 2007

Fully biodegradable high strength composites or 'advanced green composites' were fabricated using yearly renewable soy protein based resins and high strength liquid crystalline cellulose fibers. For comparison, E-glass and aramid ($Kevlar^{(R)}$) fiber reinforced composites were also prepared using the same modified soy protein resins. The modification of soy protein included forming an interpenetrating network-like (IPN-like) resin with mechanical properties comparable to commonly used epoxy resins. The IPN-like soy protein based resin was further reinforced using nano-clay and microfibrillated cellulose. Fiber/resin interfacial shear strength was characterized using microbond method. Tensile and flexural properties of the composites were characterized as per ASTM standards. A comparison of the tensile and flexural properties of the high strength composites made using the three fibers is presented. The results suggest that these green composites have excellent mechanical properties and can be considered for use in primary structural applications. Although significant additional research is needed in this area, it is clear that advanced green composites will some day replace today's advanced composites made using petroleum based fibers and resins. At the end of their life, the fully sustainable 'advanced green composites' can be easily disposed of or composted without harming the environment, in fact, helping it.

• Journal of The Korean Society of Grassland and Forage Science
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• v.28 no.2
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• pp.129-138
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• 2008

Demand for alternatives to petroleum is increasing the production of biofuels from food crops such as corn, soybeans, sorghum and sugarcane, etc. At least for the next 5 years, ethanol demand will be increased greatly in the United States and in the world. Presently, most ethanol produced in the United States is corn (Zea mays) ethanol. As a result, especially in the Americas and Southeast Asia, agricultural land is diverted to biofuel production. Even though biofuel industry has many advantage including national security, economical, energetical and sustainable impacts, it is driving grain prices up and creating considerable concern about the potential negative impacts on a wide range of food products that depend on gain : chicken, pork, beef, and dairy products such as milk, cheese, yoghurt, cream and ice cream. Feedstock crops are crops such as switchgrass(Panicum virgatum, L.), corn stover and grasses that can be used in industrial processes such as fermentation into alcohol fuels. Feedstock is no compete with food. Furthermore it is friendly environmental bioenergy crops. In Korea, with increasing demand for fossil fuels the exploration of alternative sources of liquid fuel is inevitable. I suggest Korea need to research and to develop actively on feedstock for biofuel production through this review.

• KSBB Journal
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• v.30 no.4
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• pp.161-165
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• 2015

Lactic acid and its derivatives are widely used in the food, pharmaceutical, and cosmetic industries. It is also a major raw material for the production of poly-lactic acid (PLA), a biodegradable and environmentally friendly polymer and a possible alternative to synthetic plastics derived from petroleum. For PLA production by new strains of lactic acid bacteria (LAB), we screened LAB isolates from shellfish. A total of 51 LAB were isolated from 7 types of shellfishes. Lactic acid production of individual isolates was examined using high-performance liquid chromatography using a Chiralpak MA column and an ultraviolet detector. Lactobacillus plantarum T-3 was selected as the most stress-resistant strain, with minimal inhibition concentrations of 1.2 M NaCl, 15% ethanol, and 0.0020% hydrogen peroxide. In a 1 L fermentation experiment, $\small{D}$-lactic acid production of 19.91 g/L fermentation broth was achieved after 9 h cultivation, whereas the maximum production of total lactic acid was 41.37 g/L at 24 h.

• Journal of ILASS-Korea
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• v.3 no.4
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• pp.8-15
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• 1998

The spray characteristics of emulsified fuel of W/O type has been experimentally investigated. The mixture of light oil and water by using ultrasonic energy adding system is used as the emulsified fuel. The SMD of sprayed droplet of emulsified fuel is measured by using the particle size analyzer. Major parameters of the present experimental study are the volume fraction of water in emulsified fuel, $0\sim30%$ by 5%, injection pressure, $10kg_f/cm^2\sim18kg_f/cm^2$ by $2kg_f/cm^2$, and the measurement distance, $10\sim100mm$, between injection nozzle tip and analyzer beam. Compared with light oil, the SMD of emulsified fuel is larger gradually by increasing the volume fraction of water in emulsified fuel, heightening injection pressure and increasing the spray distance. Also, In considering the fact that the pattern of drop size distribution of emulsified fuel is alike that of light oil, the real time spray in coincidence with making emulsified fuel by adding ultrasonic energy can stabilize spray pattern without modificating the injection system used by now.

• Ecology and Resilient Infrastructure
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• v.2 no.2
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• pp.177-184
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• 2015

This study assessed the performance of activated carbon (AC) amendment to treat polycyclic aromatic hydrocarbons (PAHs) including both parent- and alkylated-moieties in sediment impacted by diesel. A field-collected, diesel-impacted sediment with a NAPL content of 1% was used for the study. No. 2 diesel fuel is weathered by heating at $70^{\circ}C$ for 4 days to obtain a weathered diesel sample having C3-naphthalenes to C2-phenanthrenes/anthracenes (N2/P3) ratio similar to the original sediment. The sediment samples spiked with the weathered diesel to obtain non-aqueous phase liquid (NAPL) contents of 1, 5 and 10% were contacted with AC with a dose of 5% as sediment dry weight for 1 month. By the AC-sediment contact, the freely-dissolved equilibrium concentrations were substantially reduced. Even for sediment with 10% NAPL content, the reductions in the freely-dissolved concentrations were 92% and 75% for total parent-and alkylated-PAHs, respectively. The effect of NAPL contents on the performance of AC was negligible for parent-PAHs, while for alkylated-PAHs, a slightly reduced AC performance was observed. The results suggest that the AC amendment can be an effective option for the treatment of petroleum-impacted sediment with relatively high NAPL contents.

• Elastomers and Composites
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• v.30 no.3
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• pp.185-194
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• 1995

Membrane process has been employed to separate a specific substance from gas or liquid mixture, and treat wastewater. This is due to the fact that the substance of mixture can be permeated and separated selectively by membrane. Since Initial equipment and operation costs are not expensive, membrane process has been adopted in various fields such as petroleum Industry, chemistry, polymer, electronics, foods, biochemical industry and wastewater treatment. In this study, $CaCO_3$ particles impregnated in silicone rubber network were extracted by using supercritical carbon dioxide and pore distribution of silicone $rubber-CaCO_3$ was investigated with varying amount of extract. Silicone rubber has excellent mechanical properties such as heat-resistance, cold-resistance etc. and $CaCO_3$ has microporous structure. It is possible to make silicone $rubber-CaCO_3$ composite sheets via work-intensive kneading processes. In so doing $CaCO_3$ particles become distributed and impregnated in silicone rubber network. Supercritical carbon dioxide diffuse through composite sample, then sample is swollen. $CaCO_3$ in silicone rubber network Is dissolved in supercritical carbon dioxide, and its sites become pores. Pore distribution, pore shape and surface area are observed by SEM(scanning electron microscope) micrograph and BET surface area analyzer examination respectively. Pore characteristics of membrane suggest the possibilities that the membrane can be used for process of mixture separation and wastewater treatment.

• Journal of ILASS-Korea
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• v.27 no.4
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• pp.195-202
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• 2022

Recently, the global automobile market is rapidly changing from internal combustion engine vehicles to eco-friendly vehicles including electric vehicles. Among eco-friendly vehicles, LPG vehicles are low in fine dust and are suggested as a realistic way to replace diesel vehicles. In addition, it is more economical than gasoline in its class, showing a cost-saving effect. In Korea, the business of converting gasoline into LPG is active. Research is being conducted to apply this to hybrid vehicles. In this study, the difference in energy consumption efficiency was analyzed when LPG fuel was applied by selecting a 2-liter GDI hybrid electric vehicle. The operation of the hybrid system according to various driving characteristics was confirmed by selecting the WLTC mode. As a result, it was confirmed that the BSFC was about 5% lower than that of gasoline fuel when using LPG fuel. This is due to the active operation of the motor while driving. Optimization is required as battery consumption increases from an energy perspective.