• 한국수소및신에너지학회논문집
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• 제26권5호
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• pp.469-476
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• 2015

The purpose of this work is to investigate main factors to design a solid-state hydrogen stroage system with magnesium hydride with 10 wt% graphite using numerical simulation tools. The heat transfer characteristic of this material was measured in order to perform the highly reliable simulation for this system. Based on the measured effective thermal conductivity, a transient heat and mass transfer simulation revealed that the total performance of hydrogen storage system is prone to depend on heat and mass transfer behaviors of hydrogen storage medium instead of its inherent kinetic rate for hydrogen adsorption. Furthermore, we demonstrate that the thermodynamic aspect between equlibrium presssure and temperature is one of key factor to design the hydrogen storage system with high performance using magnesium hydride.

• 한국미생물·생명공학회지
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• 제28권5호
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• pp.264-269
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• 2000

This study is that of providing a fairly practical practival guide to the use of natural pigment in food industry. A strain isolated from marine resources was carried out the production of red pigment. The pigment showed UV absorption maxima at 520 and 550 nm. The color intensity in aqueous solution was fairly stable in the ranges of pH 5~8. The strain KS-97 produced a maximum yield of red pigment at$ 25^{\circ}C$ for 72 hrs with pH 7.0. The strain KS-97 was iden-tified a Bacillus sp. based on morphological and biochemical characterization such as a rod from, motility, spore for-mation, Gram positive and catalase production. The production of red pigment indicated that the strain Ks-97 utilized at thigh concentration of colloidal chitin as carbon sources obtained maximum yield of red pigment at $25^{\circ}C$ for 72 hrs. The highest production of red pigment was observed with cultivation in medium containing 20% colloi-dal chitin, 2.5g polypeptone, 2.5g yeast extract, 1.0g $KH_2$$PO_4$, 0.01g $MgSO_4$.$6H_2$O, 0.01g $ZnSO_4$, 0.01 g $MnSO_4$(per 1).

• Journal of Microbiology and Biotechnology
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• 제17권5호
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• pp.853-857
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• 2007

The semi-outdoor cultivation of Spirulina platens is was attempted using an underground-water-based medium. Occurrence of contaminant organisms such as Chlorella sp. and Chlamydomonas sp. was not found from a microscopic observation and bacteria were not detected from denaturing gradient gel electrophoresis(DGGE) analysis of PCR-amplified 16S rDNA during the cultivation, owing to pH control and the high quality of the underground water. The mean productivity was high at $10.5g/m^2/d$ with a range of $4.2-12.3g/m^2/d$ despite the unfavorable weather conditions of the rainy season. The cultivated S. platens is included a normal protein content of 58.9%. Consequently, the underground water improved the biomass productivity and the biomass quality because of an abundant supplementation of natural minerals and through a contaminant-free culture.

• Reproductive and Developmental Biology
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• 제33권3호
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• pp.125-131
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• 2009

The aim of this study is to investigate the effect of porcine epididymal fluid (pEF) on in vitro-maturation and subsequent fertilization of porcine follicular oocytes. Porcine cumulus-oocytes complexes retrieved from antral follicles were cultured in tissue culture medium (TCM)-l99 supplemented with pEF of different concentrations. At 48 h after culture, development of oocytes to germinal vesicle (GV) breakdown, metaphase I, anaphase-telophase I, and metaphase II were examined Significant (p<0.05) increase in the proportion of oocytes developed to MII stage was observed in oocytes cultured in pEF-containing TCM-l99 than in oocytes cultured in pEF-free TCM-199 (46.2% vs 16.7%), which was a dose-dependent manner. Subsequently, the proportion of monospermic fertilization were significantly (p<0.05) increased in oocytes cultured in the TCM supplemented with pEF than those cultured in pEF-free TCM-199 (51.0% vs 24.1%). In the second series of experiment, the percentage of MII oocytes was significantly (p<0.05) increased after exposure of oocytes to pEF during the first 22 h period of culture than after exposure of oocytes to pEF during the next 24 h of culture, while no significant difference in the percentage of monospermy was observed. The results of this study demonstrate that pEF contains at least enhancing component(s) for nuclear maturation.

• Natural Product Sciences
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• 제22권2호
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• pp.87-92
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• 2016

Endothelial dysfunction in atherosclerosis is associated with increasing oxidative stress that could be reversed by antioxidant. Therefore epigallocatechin gallate (EGCG), epicatechin gallate (ECG), epigallocatechin (EGC) and catechin (C) of tea flavonoids were investigated for their roles in regenerating endothelial cell. Peripheral blood mononuclear cells (PB-MNCs) were isolated, plated and cultured in medium with/without treatment of EGCG, ECG, EGC and C. Results showed that among all EGCG, ECG, EGC and C concentrations tested, $12.5{\mu}mol/L$ was not cytotoxic for peripheral blood-derived endothelial progenitor cells (PB-EPCs). Treatment of EGCG, ECG, EGC or C increased the percentages of CD34, CD133, VEGFR-2 expressions and suppressed hydrogen peroxide-induced percentages of reactive oxygen species (ROS) level in PB-EPCs. Taken together, our current results showed that EGCG, ECG, EGC or C of tea flavonoids could induce differentiation of PB-MNCs into PB-EPCs as well as protect PB-EPCs from oxidative damage by suppresing the intracellular ROS levels.

• International Journal of Industrial Entomology and Biomaterials
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• 제21권1호
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• pp.145-150
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• 2010

The regenerated silk fibroin with various molecular weights (MW) was prepared by different dissolution condition and the effect of coagulant on the wet spinnability of the various MW silk fibroin solutions dissolved in formic acid was investigated by the observation of wet spun filament in coagulant and the measurement of maximum draw ratio. The observation on the wet spun filament in coagulation bath revealed that good fibers without bead were formed in a high MW and a very high MW silk fibroin samples. In contrast, beads were observed in the silk fibroin sample with medium MW. The maximum draw ratio of wet spun silk fibroin filament decreased with MW reduction. The decrease of maximum draw ratio in isopropanol, acetone, DMF and THF was remarkably higher than that in methanol and ethanol, indicating that the coagulant type strongly influenced the wet spinnability. The two simple evaluation methods used in this study showed complementary information for wet spinnability: (a) The observation of filament in coagulant was effective to check a continuous fiber formation and a bead formation, and (b) the maximum draw ratio measurement was useful to examine the post drawing ability related to molecular orientation.

• ALGAE
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• 제21권2호
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• pp.245-251
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• 2006

Diurnal and age-related changes in air pressure were measured in air bladders of Ascophyllum nodosum from the Atlantic coast of Nova Scotia. Exterior and interior bladder volumes vary significantly with 4 and 6 y bladders being about 40% larger than 2 y bladders (p < 0.01). Freshly collected bladders yielded a mean pressure of 40.8 ± 6.5 cm H2O. Overnight (20 h) dark treatment at 15°C generated pressure reductions by 80% in 2 y bladders but only by about 30% in 4 and 6 y bladders. Furthermore, in 2 y bladders 8 out of 11 bladders were reduced to atmospheric pressure. Pressure losses were inversely related to pressure recovery after 2.5 h in natural daylight, but after 5 h in daylight there was no significant difference in pressure within the age groups. Even under 25% of full illumination, bladders inflated to full pressure after 5 h. The results show that differences in bladder age and bladder wall thickness have roles in diurnal patterns of bladder inflation and deflation. These results confirm that bladder inflation is based on photosynthetic O2 production and not on partial pressures of O2 in the surrounding medium as was suggested for Sargassum. Chemical analyses of fluid recovered after the interior of bladders were washed with saline showed no evidence for the occurrence of surfactant that might be responsible for maintaining the air-liquid interface.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.391-394
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• 2006

Growth characteristics of methane-propane clathrate hydrate, growing under different undercooling conditions, was investigated. After the water within pressurized vessel was fully saturated with guest gas molecules by agitation, medium was rapidly undercooled and maintained at the constant temperature. The growth of hydrate was always Initiated with film formations at the upper bounding surface of liquid pool. The visual observation using microscope revealed detailed features of subsequent crystal nucleation, migration, growth and interference occurring within liquid pool. A number of small crystals ascended and settled at the hydrate film. When undercooling was small $({\Delta}T=3.2K)$, some of the settled crystals slowly grew into faceted columns. As the undercooling increased, the downward growth of crystals underneath the hydrate film became dendritic and occurred with greater rate and with finer arm spacing. The shapes of the floating crystals were diverse and included octahedron and triangular or hexagonal platelet When the undercooling was small, the octahedral crystals were found dominant. As the undercooling increased, the shape of the floating crystals also became dendritic. The detailed characteristics of floating crystals were reported in this study.

• 한국산림과학회지
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• 제95권5호
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• pp.524-531
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• 2006

Neem tree (Azadirachta indica), native to the Indian sub-continent, has been known since the ancient time for its medicinal and insect repellent properties. In recent years, Neem has attracted global attention due to its potential as a source of natural drugs and also environment-friendly pesticides. In the households. The distribution and traditional practice on Neem can be important to the agriculturist, ethno-pharmaceutical developers and to the rural development practitioners in Bangladesh. An exploratory survey on the distribution and traditional practice on Neem tree in the rural homesteads of Chittagong coastal plain, Bangladesh, was conducted over a period of three months from September 2002 to November 2002. It was found that maximum, 64% households used seedling as planting material having 40% maximum sources Within the major tree species present in the homesteads, Neem accounted for 12% among the total individuals. It was found that the availability of Neem trees was found maximum, 31%, in the homesteads of medium sized households. Maximum, 42% individuals of Neem were found within the DBH of 10.1 to 20 cm; and 37% within the 3.1 to 6 m height classes. Neem trees were found to be used maximum, 88% for furniture. The findings of the study will be of immense importance for the rural development practitioners and ethno pharmacological developers in Bangladesh.

• 한국산림과학회지
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• 제90권6호
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• pp.788-791
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• 2001

본 연구는 기존의 토양 코어 시료 채취기 (double-cylinder hammer-driven soil core sampler)를 개량하여 원하는 토양 깊이에서 자연상태의 토양 코어 시료를 쉽고 편리하게 채취하여 운반, 보관할 수 있는 새로운 도구를 제시하기 위하여 수행되었다. 본 연구에서 제시된 도구와 이전에 일반적으로 사용되던 채취기와의 차이점은 1) 해머가 본체로부터 분리되고, 2) 내부 실린더가 2개로 분할되며, 3) 플라스틱 시료 보관통을 사용하도록 한 것 등이다. 본 도구는 적습한 산림토양을 대상으로 이용하는 것이 효과적이며, 해머 사용 전에 토양 시료의 압축을 줄이기 위하여 시료 채취기를 가능한 손으로 깊게 토양에 삽입한 후 해머 작업을 실시하는 것이 바람직할 것으로 생각된다. 본 도구는 채취된 토양 층위와 부피가 원래 토양과 같은 상태로 유지되는 깊이 40cm, 직경 5cm의 코어 시료 채취에 적합한 것으로 판단된다.