• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.6
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• pp.1104-1117
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• 1989

본 연구는 축방향의 동압축하중(axial dynamic compression)을 받는 작은 중공원판이 고변형도율(.epsilon.＞1,000/sec), 고변형률(.epsilon.=ln(h/h$_{o}$ )＞1.0)로 변형하는 재료에 대해서 연구하고자 한다.

• The Korean Journal of Food And Nutrition
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• v.6 no.4
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• pp.307-313
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• 1993

Bacillus cereus $\beta$-amylase was purified by Sephadex G-100 gel filtration, CM Sephadex C-50 ion exchange chromatography and CM Sephadex C-50 ion exchange rechromatography The purified enzyme showed 871 unit/mg of specific activity. The purified enzyme was identified as homogenious by disc PAGE, SDS-PAGE and analysis of reaction product. The purified enzyme showed optimum pH 7.0. optimum temperature 5$0^{\circ}C$, and was stable at 0~5$0^{\circ}C$ and at pH range of 6~10.

• Microbiology and Biotechnology Letters
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• v.25 no.2
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• pp.166-172
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• 1997

Aspergillus niger was selected as a strain producing the potent raw starch hydorlyzing enzyme. These experiments were conducted to investigate the conditions of the glucoa- mylase production, the purification of the enzyme, some characteristics of the purified enzyme and hydrolysis rate on various raw starches such as com, rice, potato, glutinous rice, sweet potato, wheat and barley. The optimum cultural temperature and time for the enzyme production on wheat bran medium were $30^{\circ}C$ and 96hrs, respectively. The respective addition of yeast extract and nutrient broth on wheat bran medium increased slightly the enzyme production. The enzyme was purified by ammonium sulfate fractionation and DEAE-cellulose column chromatography. The specific activity of the purified enzyme was 30.7u/mg-protein and the yield of enzyme activity was 25.8%. The purified enzyme showed a single band on polyacrylamide disc gel electrophoresis and its molecular weight was estimated to be 56,000 by SDS-polyacrylamide disc gel electrophoresis. The isoelectric point for the purified enzyme was pH3.7. The optimum temperature and pH were $65^{\circ}C$ and pH 4.0, respectively. The purified enzyme was stable in the pH range of pH 3.0-9.5 and below $45^{\circ}C$, and its thermal stability was slightly increased by the addition of $Ca^{2+}$. The purified enzyme was activated by $Co^{2+},\;Sr^{2+},\;Mn^{2+},\;Fe^{2+},\;Cu^{2+}$. Raw rice starch, raw corn starch, raw glutinous rice starch, raw sweet potato starch, raw wheat starch and raw barley starch showed more than 90% hydrolysis rate in 48hrs incubation. Even raw potato starch, most difficult to be hydrolyzed, showed 80% hydrolysis rate. The purified enzyme was identified as glucoamylase.

• Journal of Microbiology and Biotechnology
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• v.16 no.9
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• pp.1384-1391
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• 2006

The signal transduction system is one of the most important devices involved in maintaining life, and many protein kinases are included in the cellular signal transduction system. Finding a protein kinase inhibitor is very valuable, as it can be used to study cell biology and applied to pharmaceuticals. For the efficient and rapid screening of protein kinase inhibitors, two assay systems were combined; the nonradioactive protein kinase assay system that uses an FITC-labeled IRS-2 peptide and the cell-based paper disc assay system that uses Streptomyces griseus as the indicator strain. Among 330 kinds of herb extracts tested, the extract of Dalbergia odorifera exhibited the strongest inhibitory activity in the two assay systems and was selected for further isolation. Based on solvent extraction and many steps of chromatography, seven compounds were finally separated to homogeneity and their structures determined by $^{1}H$ and $^{13}C$ NMR spectroscopies. Four were to be flavonoids and identified as butin ($C_{15}H_{12}O_5$, Mw=272.07), 3'-hydroxymelanetin ($C_{16}H_{12}O_6$, Mw=300.06), liquiritigenin ($C_{15}H_{12}O_4$, Mw=256.07), and 2'-hydroxyformononetin ($C_{16}H_{12}O_{5}$, Mw=284.07). 3'-Hydroxymelanetin inhibited the phosphorylation of the GSK3 protein by Akt to 37% at a concentration of $10{\mu}g/ml$ and showed the strongest cytotoxicity ($ED_{50}<50{\mu}g/ml$) against the human cancer cell line HCT116. Under the same conditions, liquiritigenin also inhibited the phosphorylation of GSK3 by Akt to 26%, and its cytotoxicity against the HCT116 cell line was lower than $100{\mu}g/ml$.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.3
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• pp.374-381
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• 2013

The purpose of this study was to analyze the antioxidant effects and antimicrobial activity of extracts from yacon powder. The total polyphenol contents of yacon powder extracted with methanol was 38.5 mg/g, while extracted with water was 24.0 mg/g. Extractions with methanol were therefore more effective than with water. The total flavonoid contents of yacon powder extracted with methanol was 9.2 mg/g, while that with water was 7.8 mg/g. The electron donating ability of yacon powder extracts, natural antioxidant, and artificial antioxidant at 1.0 mg/mL arranged in order of decreasing concentration were ascorbic acid (98.7%) > BHT (44.7%) > methanol extract (12.1%) > water extract (7.8%). Nitrite-scavenging ability of yacon powder extracted with methanol at pH 1.2 was 13.1%, while that of powder extracted with water at pH 1.2 was 6.8%. And, the hydroxyl radical scavenging activities of yacon powder with methanol at 5 mg/mL was 40.2%. The antimicrobial activity of yacon powder extracted with methanol could be detected on Bacillus cereus ($10,000{\mu}g/disc$) and Staphylococcus aureus ($10,000{\mu}g/disc$).

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.6
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• pp.1572-1581
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• 1994

Heat transfer characteristics in a rotating heat pipe with evaporator of the rotating disc and the condenser of the screwed groove is investigated by numerical method for various dimensionless film thicknesses, Re, C_{p}{\Delta}T/h_{fg}$, rotational speed and working fluids. The temperature difference between evaporator wall and vapor increases a little, but the temperature difference between condenser wall and vapor decreases rapidly as Re increases. As the dimensionless film thickness decreases, the temperature difference of evaporator and condenser decreases. As the rotational speed increases, the temperature difference between evaporator wall and vapor increases but the temperature difference between condenser wall and vapor decreases. The Nusselt number can be shown as a function of dimensionless film thickness and Re, that is $Nu=0.963\cdot(\delta^{-1}(\omega/\vpsilon)^{-1/2}{\cdot}Re^{0.5025})$.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.3
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• pp.45-53
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• 2017

Disc harrow-type composite working implements of tractors are able to work almost 15km/hr. Soil reversing and plowing of agricultural fields are thereby faster than the existing rotavator speed of 2.5 km/h. In Korea, its supply process is being delayed because of the traditional tillage method of rotavator plowing operations. To develop products suitable for the domestic environment, an analysis and inspection was performed on the products of advanced specifications. 3D modeling was performed on main parts and frames using 3D scanner.

• The Korean Journal of Zoology
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• v.5 no.1
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• pp.35-38
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• 1962

Two subspecies are known to Family Hylidae(Order Anura) in Korea : namely , Hylaarborea japonica GUENTHER and H.a.stepheni BOULENGER, and they have been hitherto distinguished as different subspecies from four characteristics : the rate of interorbital to incternasal length, the rate of diameter of tympanum to diameter of 3 rd finger disc, the rate of the length of inner metatarsal tubercle to diameter of 3 rd finger disc, and the rate of inner metatarsal tubercle to the length of lst toe. The author has compared the above to subspecies for the characteristics with 123 individuals collected from ten different localities in Korea and has found that their fluctation curves overlap each other. The author considers, therefore, that the four characteristics could not be assumed as keys for the classification of the two subspecies and has reached the conclusion that these two subspecies should be regarded as one subspecies and Hyla arborea japonica GUENTHER should be given to both of them as the subspecies name.

• Smart Structures and Systems
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• v.22 no.6
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• pp.643-662
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• 2018

One of the methods for investigation of mechanical behavior of materials is numerical simulation. For simulation, its need to model behavior is close to real condition. PFC is one of the rock mechanics software that needs calibration for models simulation. The calibration was performed based on simulation of unconfined compression test and Brazilian test. Indeed the micro parameter of models change so that the UCS and Brazilian test results in numerical simulation be close to experimental one. In this paper, the effect of four micro parameters has been investigated on the uniaxial compression test and Brazilian test. These micro parameters are friction angle, Accumulation factor, expansion coefficient and disc distance. The results show that these micro parameters affect the failure pattern in UCS and Brazilian test. Also compressive strength and tensile strength are controlled by failure pattern.

• Polymer(Korea)
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• v.34 no.5
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• pp.398-404
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• 2010

We fabricated sponge and poly(lactide-co-glycolide)(PLGA) scaffolds impregnated demineralized bone particle(DBP)(DBP/PLGA) and investigated proper condition to proliferation and phenotype maintenance of intervertebral disc(IVD) cells by comparison between DBP/PLGA scaffold and DBP sponge. DBP/PLGA scaffolds were prepared by solvent casting/salt leaching. Human IVD cells were seeded in scaffolds of two types. Cell viability and proliferation according to scaffolds were analyzed by WST assay and SEM. RT-PCR was assessed to measure mRNA expression of aggrecan and type II collagen of human IVD cells. In WST assay results, cell viability in scaffolds impregnated DBP/PLGA scaffold were higher than DBP sponge. We could observe that disc cell mRNA expressed better in DBP/PLGA scaffold than DBP sponge. We concluded that the using of DBP/PLGA in terms of scaffold fabrication for bio-disc with human IVD cells is helpful growth of disc cells maintenance of phenotypes.