• Journal of Aquaculture
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• v.11 no.4
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• pp.521-528
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• 1998

The influence of starvation on survival, growth and feeding incidence of larval tiger puffer Takifugu rubripes was investigated for 16 days after let them hatched at the temperature of 16.5~18.5${\circ}C$. The effect by delayed initial feeding on larvace was also studied. Almost all larvae began to be fed from the stage of yolk absorption about 5 days after hatching, in which rearing trials revealed that their survival and growth were influenced by food availability. Survival of unfed larvae, which stated to decrease drastically since the oil globule was exhausted about 9 days after hatching, dropped to 50% and 0% respectively on the 11.5th and 16th day. the difference of growth between fed and unfed larvae came into sight on about 5th day after hatching when the initial feeding was started, and had reduced in proportion to the length of starvation period. The condition factors for the unfed larvae were lower than thost of the fed. Of the larvae which had starved less than 5 days, more than 80% could consume food upon feeding. No fish had the ability in having food after 10 days. It appeared that the turning point of recover for the starving larvae came on 7th or 8th day. Their taking-food ability seemed to be affected by the change in swimming activity which depended on the duration of starvation. For the seed production of tiger puffer, therefore, feeding should be initiated as soon as possible, so as to enhance the production and survival of healthy seeds.

• Clean Technology
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• v.11 no.4
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• pp.195-204
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• 2005

A new condensation process for manufacturing N-acyl taurates which generates less pollutant and produces more than 60 % yield in comparison with the conventional process has been developed in this work. Its optimum process conditions are at $210{\sim}230^{\circ}C$ of reaction temperature and 6 ~ 9 hour of reaction time when Parasol 123 of petroleum refired oil is employed as process solvent and mixed catalysts of sulfonic acid and phosphoric acid are utilized as process catalyst. And the qualities of N-acyl taurates produced by this new process are similar to or better than those of imported product judging from their acid value, amine value and color. Thus, it can be said that the newly developed process for manufacturing N-acyl taurates in this work is better than the conventional process. The physical properties of N-acyl taurates produced in this work such as surface tension, foaming power, foaming stability, hard water stability, and emulsifying power etc. were compared with those of commercially available anionic surfactants. And the experimental results show that N-acyl taurates shows good physical properties and that they can be alternative to conventional anionic surfactants.

• Journal of the Korean Chemical Society
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• v.38 no.9
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• pp.640-652
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• 1994

This work is undertaken to determine alcohol homologues so-called fusel oil that may be present in the Korean folk sojues (distilled liquor) made from grains and to describe sample preparation and analytical method by GC-FID-MS. Solid phase extraction method for sample preparation by using porous styrene divinyl benzene polymer (Porapak Q) was compared with steam distillation and solvent extraction method. Retention behaviors of homologous series of alcohols were also studied. Log values of retention time, molecular weight, boiling point, and capacity factor of alcohols showed linear correlations to the carbon number of an alcohol, to the oven temperature, and to the dielectric constant. Components such as methyl alcohol, n-propyl alcohol, isobutyl alcohol, isopentyl alcohol, and phenethyl alcohol have been identified. The more amount of isopentyl alcohol than other alcohols are contained in the Korean folk sojues, while that of n-propyl alcohol are contained in Chinese kaoliangchiew. Degree of similarity or dissimilarity and classification of the individual samples were discussed using multivariate statistical analysis(principal components analysis) based on GC data.

• Polymer(Korea)
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• v.30 no.6
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• pp.505-511
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• 2006

We tried to prepare polystyrene composite particles containing carbon black by suspension polymerization with water as a reaction medium. Hydrophobic silica was selected as a stabilizer and oil-soluble azobisisobutyronitrile (AIBN), as an initiator. All polymerization reactions were carried out at a fixed temperature of $75^{\circ}C$. Stabilizer concentration was varied from $0.17{\sim}3.33wt%$ compared to water, where particles with $7.96{\mu}m$ in average diameter were obtained at 1.57 wt% of stabilizer. Increase in divinylbenzene concentration, as a crosslinking agent, from $0.1{\sim}1.0 wt%$ compared to monomer exhibited a large increase in average particle diameter Incorporation of 1wt% of carbon black compared to monomer produced an increase in average diameter It is speculated that viscosity lower than that necessary to induce even dispersion of carbon black particles led to poor dispersion, and as a result, large particles. For a styrene mixture containing 3 wt% carton black compared to monomer, enhanced dispersion due to an increase in carbon black concentration reduced average particle diameters. For styrene mixtures containing 1 and 3 wt% carbon black compared to monomer, preparticles before polymerization and polymer composite particles after polymerization showed a similar tendency towards particle formation. When carbon black concentration compared to monomer was increased to 5 and 7 wt%, styrene mixtures exhibited a large increase in viscosity and thus better dispersion of carbon black particles, which led to a decrease in preparticle diameters. However, these particles experienced agglomeration in the polymerization process, and polystyrene composite particles increased in average diameter.

• Journal of Life Science
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• v.23 no.10
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• pp.1273-1279
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• 2013

Aromatic hydrocarbons, such as phenol, have been detected frequently in wastewater, soil, and groundwater because of the extensive use of oil products. Bacterial strains (56 isolates) that degraded phenol were isolated from soil and industrial wastewater contaminated with hydrocarbons. GN13, which showed the best cell growth and phenol degradation, was selected for further analysis. The GN13 isolate was identified as Neisseria sp. based on the results of morphological, physiological, and biochemical taxonomic analyses and designated as Neisseria sp. GN13. The optimum temperature and pH for phenol removal of Neisseria sp. GN13 was $32^{\circ}C$ and 7.0, respectively. The highest cell growth occurred after cultivation for 30 hours in a jar fermentor using optimized medium containing 1,000 mg/l of phenol as the sole carbon source. Phenol was not detected after 27 hours of cultivation. Based on the analysis of catechol dioxygenase, it seemed that catechol was degraded through the meta- and ortho-cleavage pathway. Analysis of the biodegradation of phenol by Neisseria sp. GN13 in artificial wastewater containing phenol showed that the removal rate of phenol was 97% during incubation of 30 hours. The removal rate of total organic carbon (TOC) by Neisseria sp. GN13 and activated sludge was 83% and 78%, respectively. The COD removal rate by Neisseria sp. GN13 from petrochemical wastewater was about 1.3 times higher than that of a control containing only activated sludge.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2498-2508
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• 1993

$Al/SiC/Al_{2}O_{3}$ hybrid composites are fabricated by squeeze infiltration method. From the misconstructive of $Al/SiC/Al_{2}O_{3}$ hybrid composites fabricated by squeeze infiltration method, uniform distribution of reinforcements and good bondings are found. Hardness value of $Al/SiC/Al_{2}O_{3}$ hybrid composites increases linearly with the volume fraction of reinforcement because SiC whisker and $Al_{2}$O$_{3}$ fiber have an outstanding hardness. Optimal aging conditions are obtained by examining the hardness of $Al/SiC/Al_{2}O_{3}$ hybrid composites with different aging time. Tensile properties such as Young's modulus and ultimate tensile strength are improved up to 30% and 40% by the addition of reinforcements, respectively. Failure mode of $Al/SiC/Al_{2}O_{3}$ hybrid composites is ductile on microstructural level. Through the abrasive wear test and wear surface analysis, wear behaviour and mechanism of 6061 aluminum and $Al/SiC/Al_{2}O_{3}$ hybrid composites are characterized under various testing conditions. The addition of SiC whisker to $Al/SiC/Al_{2}O_{3}$ composites gives rise to improvement of the wear resistance. The wear resistance of $Al/SiC/Al_{2}O_{3}$ hybrid composites is superior to that of Al/SiC composites. The wear mechanism of aluminum alloy is mainly abrasive wear at low speed range and adhesive and melt wear at high speed range. In contrast, that of $Al/SiC/Al_{2}O_{3}$ hybrid composites is abrasive wear at all speed range, but severe wear when counter material is stainless steel. As the testing temperature increases, wear loss of aluminum alloy decreases because the matrix is getting more ductile, but that of $Al/SiC/Al_{2}O_{3}$ hybrid composites is hardly varied. Oil lubricant is more effective to reduce the wear loss of aluminum alloy and $Al/SiC/Al_{2}O_{3}$ hybrid composites at high speed range.

• Journal of the Mineralogical Society of Korea
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• v.23 no.3
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• pp.199-209
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• 2010

Coal gasification technology in the sector of domestic clean coal technologies is being into the limelight since recent dramatic rise of international oil price. In this study, we used a low rank coal from Inner Mongolia, China as a starting material for gasification. Various properties including optical, mineralogical, X-ray spectroscopic, X-ray diffraction, and drying property were measured and tested in order to estimate the suitability of the coal to gasification. The coal was identified as a brown coal of lignite group from the measurement of vitrinite reflectance. The coal has very low slagging and fouling potentials, and the ignition temperature is about $250^{\circ}C$. The major impurities consist of quartz, siderite, and clay minerals. Additionally, the coal had moisture content above 28%. Tests for finding effective drying method showed that the microwave drying is more effective than thermal drying.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.1
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• pp.15-21
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• 1984

In order to ascertain the practical possibility of home made retort pouches for production of retort pouch foods in factory, two kinds of retortable pouches, i. e. 3 ply film (polyester film/Al. foil/casting polypropylene) and 4 ply film(polyester film/Al. foil/nylon/casting poll·propylene) were developed in Korea, and then, their physical properties, such as physical strength, heat resistance during thermal processing and preservability of foods and sanitary safety, were tested and compared with the foreign made pouches. The results obtained were summarized as follows. a. The physical strength of home made retort pouches in processing model foods(soybean oil 5 %, acetic acid 2%, starch 5 % and water to 100 %) was equal to that of foreign made pouches at accelerated examination condition($38^{\circ}C$, 98 % RH). But the lamination strength of home made products was a little bit superior to that of foreign made products. b. Home made retort pouches(SAMA-4 ply and SAMA-3 ply pouch) packed with rice or curry was possible to bear the thermal processing at $135^{\circ}C$ and shelf-life was one year or more at ambient temperature($20^{\circ}C$). c. Sanitary safety test showed that these home made retort pouches were acceptable comparing to the regulation recommended by the Ministry of Health and Social Affairs.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.12
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• pp.1881-1888
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• 2014

Pre-thermal treatment is important to minimize quality changes during main cooking or storage. In this study, to optimize pre-thermal treatment of carrots, three types of pre-thermal treatments were applied to carrots and quality changes such as physicochemical, nutritional, or sensory properties were observed. Washed and sliced carrots were thermally treated by hot-water immersion ($100^{\circ}C$, 1~10 min), steaming ($100^{\circ}C$, 1~10 min), and stir-frying with oil (10~80 sec). Carrot tissue was maintained until 2 min hot-water immersion or steaming, and they were damaged by just 30 sec of stir-frying. Color and hardness were significantly affected by treatment time and temperature. Color was completely changed after 5 min and 7 min by hot-water and steam treatments, respectively. Hardness decreased to 44% compared with fresh carrot (4,500 g) after 1 min, 3 min, and 20 sec of hot-water, steam, and stir-frying, respectively. For nutritional changes, ascorbic acid, organic acid, and peroxide activity were reduced by all treatments compared with fresh carrot. Especially, succinic acid was dramatically reduced by hot-water treatment. Otherwise, free sugar contents were increased with greater treatment time in all samples. In this study, pre-thermal treatment of carrot was optimal at 2 min steaming treatment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.12 no.2
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• pp.176-187
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• 1983

Volatile flavor components of garlic and factors which influence on its flavors were reviewed. Growth, storage and processing conditions influence on the flavor intensity of garlic. To intensify garlic flavors, it is desirable that sufficient sulfate nutrition be supplied to the soil of growing garlic and that the suggested proportions of mineral composition and water content be considered. And to maintain the flavor intensity of post harvested garlic, flavor losses taken place during over inter storage mainly due to respiration, sprout and decay, have to be minimized. Among the various storage methods, combination method of post harvest hot-air drying and low temperature ($0^{\circ}C$), low humidity (RH 70-75%) is useful. The flavor of processed garlic is very much decreased as compared with that of fresh, and the decreasing rate of flavors depends on processing method. The synthetic garlic flavors were obtained by three types based on intermediate thiosulfinate, S-alk(en) yl-$\small{L}$-cyteine sulfoxlde-alliinase fission products and $\small{L}$-5-alk (en)yl thiomethylhydantoin ${\pm}$ S-oxides. These synthetic garlic flavors may be promised to be applied to food additives.