• 한국미생물·생명공학회지
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• 제32권4호
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• pp.366-370
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• 2004

Four chitinase producing bacteria, Arthrobacter nicotinae CH4, Arthrobacter nicotinae CHI3, Arthrobacter sp. CH5 and Micrococcus sp. CH3, were isolated from small crabs and shrimps. We investigated the optimum medium condition for the production of enzyme and high cell mass. The preferable medium composition was as follows: colchitin 0.1 %(w/v), glycerol 0.25%(w/v) and yeast extract 0.05%(w/v) in minimal midium ($K_{2}HPO_{4}$ 0.7 g/l, $KH_{2}PO_{4}$ 0.3 g/l, $MgSO_{4}{\cdot}5H_{2}O$ 0.5 g/l, $FeSO_{4}}{\cdot}7H_{2}O$ 0.01 g/l, $ZnSO_{4}$ 0.001 g/l, $MnCI_2$ 0.001 g/l, pH 7.0). This cell culture medium could be used directly as sample for measuring chitinase activity. Because it hardly conreducing sugar such as glucose (blank value=0), the detected reducing sugar can be considered as a chitinase reaction product. The results can be used for easy preparation method for determination of enzyme activity and analysis of enzyme-substrate reaction in step of screening of chitinase producing bacteria.

• 천문학회지
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• 제39권3호
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• pp.73-80
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• 2006

We analyze the extinction law towards several B1V stars-members of our Galaxy, searching for possible discrepancies from the galactic average extinction curve. Our photometric data allow to build extinction curves in a very broad range: from extreme UV till infrared. Two-colour diagrams, based on the collected photometric data from the ANS UV satellite, published UBV measurements and on the infrared 2MASS data of the selected stars, are constructed. Slopes of the fitted straight lines are used to build the average extinction curve and to search for discrepant objects. The selected stars have also been observed spectroscopically from the Terskol and ESO Observatories; these spectra allow to check their Sp/L's. The spectra of only about 30% of the initially selected objects resemble closely that of HD144470, considered as the standard of B1 V type. Other spectra either show some emission features or belong clearly to another spectral types. They are not used to build the extinction curve. Two-colour diagrams, constructed for the selected B1 V stars, showing no emission stellar features, prove that the interstellar extinction law is homogeneous in the Galaxy. Both the shape of the curve and the total-to-selective extinction ratio do not differ from the galactic average and the canonical value(3.1) respectively. The circumstellar emissions usually cause some discrepancies from the average interstellar extinction law; the discrepancies observed in the extraterrestrial ultraviolet, usually follow some misclassifications.

• 한국생산제조학회지
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• 제18권5호
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• pp.514-520
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• 2009

Titanium is one of the most attractive materials due to their superior properties of high specific strength and excellent corrosion resistance. The applications in aerospace and medical industries demand machining process more frequently to obtain more precise products. Machining of titanium is faced with strong challenges such as increased component complexity i.e. airframe components manufacturing processes. The machining cost on titanium have traditionally demanded high cutting tool consumable cost and slow machining cycle times. Similarly, the high wear of the cutting tools restricts the cutting process capabilities. Titanium screws applied to fasten parts In the several corrosion environment. In the thread cutting of titanium alloys, the key point for successful work is to select proper cutting methods and tool materials. This study suggests a guidance fur selecting the cutting methods and the tool materials to improve thread quality and productivity. Some experiments investigate surface roughnesses, cutting forces and tool wear with change of various cutting parameters including tool materials, cutting methods, cutting speed. As the results, the P10 type insert tip was assured of the best for thread cutting of Ti-6Al-4V titanium alloy. Also the initial depth of infeed was desirable to use the value below 0.5mm as the uniform cutting area method is applied.

• Journal of Chest Surgery
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• 제17권2호
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• pp.231-243
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• 1984

Despite its known limitation in the diagnostic value, the electrocardiography is one of the most common and routine examinations in the management of the patients with cardiac problems. The clinical results of 291 patients who underwent isolated mitral valve replacement from October 1978 to June 1983 were already reported. Their electrocardiograms were studied to assess the value of electrocardiographic examination in following the patients after valve replacement. The patients were divided into 5 groups beforehand according to the types of valve lesion on the bases of preoperative diagnosis and operative findings: Groups I: stenosis, I1: stenosis-dominant mixed, II1: equally mixed, IV: insufficiency-dominant mixed, and V: insufficiency. Their preoperative cardiac rhythm was sinus in 39.2% and atrial fibrillation in 59.1% of the patients. Seventy-three [42.4%] of the patients with atrial fibrillation gained sinus rhythm after operation, occurring in 67 from the day of surgery, and 42 returned to atrial fibrillation while 37 kept sinus rhythm at the follow-up end [mean follow-up period, 13.4\ulcorner1.4 months]. The P waves on the electrocardiograms of the preoperative sinus rhythm in 114 patients were normal in 5.3% and the findings of left atrial enlargement in 94.7% of the cases. They were normal in 42.1% and the findings of left atrial enlargement in 57.9% of the 140 patients with sinus rhythm at the follow-up. The preoperative major chamber enlargement was the right ventricle in Group I while it was the left ventricle in Group V, and it was in-between in Groups II-IV. The postoperative regression of the findings in ventricular enlargement was statistically significant only in Groups I and V. These results may suggest the importance of the serial electrocardiograms in following the patients with mitral valve replacement on the bases of outpatient. The electrocardiographic follow-up data were presented in patients with suspected or proved tissue valve failures.

• Journal of Microbiology and Biotechnology
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• 제19권5호
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• pp.447-454
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• 2009

The transport of spermidine into a cyanobacterium, Synechocystis sp. pec 6803, was characterized by measuring the uptake of $^{14}C$-spermidine. Spermidine transport was shown to be saturable with an apparent affinity constant ($K_m$) value of $67{\mu}M$ and a maximal velocity ($V_{max}$) value of 0.45 nmol/min/mg protein. Spermidine uptake was pH-dependent with the pH optimum being 8.0. The competition experiment showed strong inhibition of spermidine uptake by putrescine and spermine, whereas amino acids were hardly inhibitory. The inhibition kinetics of spermidine transport by putrescine and spermine was found to be noncompetitive with $K_i$ values of 292 and $432{\mu}M$, respectively. The inhibition of spermidine transport by various metabolic inhibitors and ionophores suggests that spermidine uptake is energy-dependent. The diminution of cell growth was observed in cells grown at a high concentration of NaCl. Addition of a low concentration of spermidine at 0.5 mM relieved growth inhibition by salt stress. Upshift of the external osmolality generated by either NaCl or sorbitol caused an increased spermidine transport with about 30-40% increase at 10 mosmol/kg upshift.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.950-952
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• 1999

In this paper, we are studied a electrical properties study with P.D.GEORGE/STER LING Co. P.B 302-LV-2 POLYBUTADIENE RESIN which is used for VPI(Vacuum Pressure Impregnation)processing of field magnet and armature of traction motor in Korean national railroad at present was carried out its FT-IR (Fourier Transform Infra-Red) volume resistivity characteristics. The varnishes were experimented with the temperature range form $25[^{\circ}C]$ to $180[^{\circ}C]$ and applied voltage were supplied at 100, 250, 500, 1,000[V]. In this condition, the volume resistivity for specimens were measured. From the above study, the following data obtained for volume resistivity. It can be confirmed that velume resistivity with the increase of temperature is lower rapidly from room temperature to $130[^{\circ}C]$, and it is lower slowly at temperature higher than $130[^{\circ}C]$. Volume resistivity value is higher, according as the specimen is thick gradually. As the applied voltage is higher in the same temperature, volume resistivity value is lower.

• 한국의류학회지
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• 제33권2호
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• pp.222-229
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• 2009

The natural dyeing of cotton fabrics with Rumex crispus L. root extract was investigated. The dyeability of Rumex crispus L. root extract was evaluated with conditions of concentration, temperature, time, repeat-numbers, pH, mordants variables, methods of mordanting, color fastness and antibacterial activity, etc. The maximum V-visible spectrum possessed absorption band of Rumex crispus L. extract appeared at 274nm and 336nm. The amount of dyes extracted was increased with extracting concentration, temperature and time. The K/S value increased with increasing dyeing concentration and repeat-numbers. The K/S value increased with increasing dyeing temperature and time, the exhaustion was saturated in $90^{\circ}C\;and\;80min$, respectively. Surface colors of fabrics dyed with pH 3, 7, 11 extract were RP-R-YR-Y range. The light fastness and washing fastness showed good results in Fe-mordanted. The dry leaning fastness appeared more than 4 grade. Rubbing fastness was better in dry methods han that in wet methods. In the result of antibacterial activity, the decrease rate was 9.9% to Staphylococcus aureus with the dyed fabric of cotton.

• Journal of Microbiology
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• 제43권6호
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• pp.555-560
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• 2005

Laccase is one of the ligninolytic enzymes of white rot fungus Trametes versicolor 951022, a strain first isolated in Korea. This laccase was purified 209-fold from culture fluid with a yield of $6.2\%$ using ethanol precipitation, DEAE-Sepharose, Phenyl-Sepharose, and Sephadex G-100 chromatography. T. versicolor 951022 excretes a single monomeric laccase showing a high specific activity of 91,443 U/mg for 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) as a substrate. The enzyme has a molecular mass of approximately 97 kDa as determined by SDS-PAGE, which is larger than those of other laccases reported. It exhibits high enzyme activity over broad pH and temperature ranges with optimum activity at pH 3.0 and a temperature of $50^{\circ}C$. The $K_m$ value of the enzyme for substrate ABTS is $12.8{\mu}M$ and its corresponding $V_{max}$ value is 8125.4 U/mg. The specific activity and substrate affinity of this laccase are higher than those of other white rot fungi, therefore, it may be potentially useful for industrial purposes.

• Bulletin of the Korean Chemical Society
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• 제13권2호
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• pp.127-131
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• 1992

Changes in network structures of ${\alpha}-Nb_2O_5$ in the X MgO+(1-X) ${\alpha}-Nb_2O_5$ solid solutions occurring as the MgO doping level (X) was varied were investigated by means of infrared spectroscopy and X-ray analysis. X-ray diffraction revealed that all the synthesized specimens have the monoclinic structure. The FT-IR spectroscopy showed that the system investigated forms the solid solutions in which $Mg^{2+}$ ions occupy the octahedral sites in parent crystal lattice. Electrical conductivities were measured as a function of temperature from 600 to $1050{\circ}$ and $P_{O2}$ form $1{\times}10^{-5}$ to $2{\times}10^{-1}$ atm. The defect structure and conduction mechanism were deduced from the results. The $1}n$ value in ${\alpha}{\propto}{P_{O2}^{1}n}}$ is found to be -1/4 with single possible defect model. From the activation energy ($E{\alpha}$ = 1.67-1.73 eV) and the1/n value, electronic conduction mechanism is suggested with a doubly charged oxygen vacancy.

• 산업식품공학
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• 제15권1호
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• pp.22-27
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• 2011

본 연구에서는 강원도 춘천지역에서 발생하는 환경 오폐수를 시료로 하여 미생물을 혼합하여 제조한 수질정화제를 실제 하천과 호수의 오염환경과 유사한 배양기내에서 생물학적반응을 시켜오염물질의정화정도를측정하고평가하였다. 사용된 미생물은 식물성 유산균(vegetable Lactobacillus fermentum), 효모(Saccharomyces cerevisiae)와 고초균(Bacillus subtilis)이다. 두가지의미생물혼합제를투입하여정화정도를 실험하였다. 실제 하천에 투입하여 정화되는 과정과 유사하게 반응을 시키고자 반응 온도는 $21({\pm}3)^{\circ}C$로 하였으며 완전교반을 진행하였다. 사용한 시료의 오폐수의 오염도와 미생물에 의한 정화정도를 평가하기 위하여 총질소 함량과 총인 함량을 측정하였다. V.L.F.와 S.C.의 혼합물로 구성된 혼합제의 경우 총질소함량을 감소시키는데 매우 효과적임을 보여주었으며, V.L.F., S.C.,와 B.S.로 구성된 혼합제의 경우 그 총인의 함량을 저감화하는데 효과적임을 알 수 있었다. 본 실험에서 얻어진 실험 데이터를 통하여 V.L.F.와 S.C.의 혼합제가 오폐수의 정화반응에서 나타나는 반응상수값을 도출하였으며 그 값은 0.178 $day^{-1}$이었다. 본 연구의 결과를 바탕으로 저감화하고자 하는 성분에 따라 미생물의 종류와 그 혼합비를 조절하는 최적화과정이 필수적임을 알 수 있었으며 또한 곡선적합으로 도출한 반응상수값은 미생물을 이용하여 호수와 하천의 정화정도를 simulation함에 필요한 실험인자로서 응용이 가능하게 되었다.