• Journal of the Mineralogical Society of Korea
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• v.7 no.2
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• pp.91-96
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• 1994

중.저준위 방사성 폐기물의 대표적인 핵종인 137Cs, 90Sr에 대한 캐올리나이트의 흡착특성을 수용액의 이온강도와 pH의 영양하에서 알아보았다. 흡착실험은 회분식으로 하였고, 사용한 수용액은 NaCl, CaCl2, MgSO4, KCL 각각을 10-1, 10-2, 10-3, 10-4 mole/$\ell$로 하였다. 수용액광물 평형상태의 pH를 4.5, 7.0, 10.5로 조절하였다. 실험결과 캐올리나이트의 Cs, Sr 흡착은 이온강도와 pH에 상당한 영향을 받으며, Sr 흡차에 양이온들의 경쟁은 Ca2+ Mg2+>K+>Na+ 순을 보이고, Cs의 경우에는 K+>Ca2+ Mg2+>Na+의 순을 보인다. 이는 수용액상에서 이온들의 수호에너지와 관련되며, 광물입자와 이온들의 물구조변환특성에 의해 설명된다. Cs과 Sr 사이에 흡착우선성은 산성 내지 약알카리에서는 Cs이 Sr보다 흡착이 잘 되나, 강알칼리성 환경에서는 Sr이 Cs보다 흡착이 잘 되는 pH 의존성을 보였다. 수용액의 pH가 증가함에 따라 핵종의 흡착량이 증가하는데, 이는 캐올리나이트의 흡착자리인 실라놀과 알루미놀에 의한 제타전위가 pH에 의존함과 잘 일치한다.

• Electronics and Telecommunications Trends
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• v.16 no.1 s.67
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• pp.56-70
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• 2001

마이크로파대 이상의 높은 RF 전파는 신호레벨이 비교적 작고 간섭현상에 매우 민감한 특성을 가지고 있다. 따라서 이러한 미소한 입력전파의 수신시 수신기 전체의 감도를 높이고 잡음을 저감시킬 목적으로 사용되는 고주파 증폭기가 저잡음 증폭기이다. 본 고에서는 LNA의 기본적 특성분석과 지능형교통시스템에 응용되는 5.8GHz대 단거리전용통신용 LNA를 구현하기 위한 기본 FET 증폭기의 전기적 특성을 연구하고 직렬 궤환에 의한 최소잡음과 최소 입력 정재파비의 최적 설계 파라미터를 도출하였다.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.68-73
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• 1999

In order to overcome same disadvantages of acidic solubilization of pectin from apple pomace, enzymatic selective solubilization with exo-polygalacturonase was developed. According to analyses of the effects of temperature, pH and reaction time on extraction yield, the maximum yield by the enzymatic method, shown under the extraction condition of $45^{\circ}C$, pH 7 and 60 hours, was 31.0%, whereas the yield from an acidic method was 8%. Also the quality of pectin extracted by the enzymatic method was to that from acidic solubilization. The purity and methoxyl content of enzyme-extracted pectin were 80.1% and 6.36%, respectively, which were higher than 75.7% and 2.44% of acid-solubilized pectin. Viscosity average molecular weights of enzymic extracted and acid solubilized pectins were $1.50{\times}10^4\;and\;7.66{\times}10^4$, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.2
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• pp.84-90
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• 2001

This study was performed to know the effect of depolymerized alginate obtained by hydrolysis of alginate through a heating process at $121^{\circ}C$ on intestinal environment, Rats were fed with diets containing $1\%$, $5\%$, and $10\%$ of each depolymerized alginate (HAG-10, HAG-50, HAG-100 and alginate) for 35 days, The changes of weight, moisture content, pH and volatile basic nitrogen (VBN) of fecal, and a short chain fatty acids (SCFA) were checked in the rats. The fecal weight and moisture content were the highest in rats fed with alginate diets (p<0.01), followed by HAG-100, HAG-50 and HAG-10 in order. The $5\%$ of HAG-50 diets induced a significant increase in contents of protein and lipid of feces, resulting in the decrease of apparent digestibility of protein and lipid (p<0.01). The pH and VBN content in feces of the rats decreased in $5\%$ and $10\%$ of HAG-50 diets, but $10\%$ of HAG-100 diets; $5\%$ and $10\%$ of alginate diets brought about an increase of fecal pH and VBN (p<0.01), The amount of n-butyric acid in feces was increased while propionic and acetic acid contents decreased significantly (p<0.01) in diets containing $5\%$ and $10\%$ HAG-50. However, the feces of rat fed diet containing $5\%$ and $10\%$ alginate showed a tendency to being opposite in results than that of HAG-50.

• Microbiology and Biotechnology Letters
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• v.1 no.1
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• pp.37-42
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• 1973

C-74 belonging to the genus of Aspergillus species was selected from two hundred and seventy microorganisms stored at the lab, of microbiology. 1. Sample Inulase was precipitated mainly at pH 8 to 5 by isoelectric point fraction method. 2. The optimum pH of Inulase activity of the enzyme from C-74 strain was about 3.0 3. The optimum temperature of Inulase activity of the enzyme from C-74 strain was about $55^{\circ}C$ 4. The Inulase from C-74 strain was stable at $50^{\circ}C$ for 10mins. 5. The range of the pH stability of the Inulase from C-74 strain was about 2.5-4.5 6. Effect of metal ions on the Inulase activity of the enzyme from C-74 strain was activated by Mg$\^$++/, Sb$\^$+++/ and inhibited by Ag$\^$++/, Hg$\^$++/.

• Radiation Oncology Journal
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• v.13 no.3
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• pp.205-214
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• 1995

Purpose : To investigate the effect of Ginkgo biloba extract (GBE) on hypoxic cell fraction and metabolic status in fibrosarcoma (FSa II) of C3H mouse. Materials and Methods : Fibrosarcoma (FSa II) 6 mm in diameter, growing in the right hindleg muscle of C3H mouse was used for estimation of hypoxic cell fraction using comparison of $TCD_{50}$. Radiation was given one hour after administration of GBE (100 mg/kg. i.p.) with or without priming dose of GBE (100 mg/kg, i.p.) given 24 hours earlier. Radiation was also given under air breathing condition or clamp hypoxia without GBE as controls. $^{31}p$ NMR spectroscopy was performed before and one hour after administration of GBE with or without priming dose of GBE. Results : $TCD_{50/120's}$ were 81.7 (77.7-86.0) Gy when irradiated under clamped hypoxia 69.6 (66.8-72.5) Gy under air breathing condition. 67.5 (64.1-71.1) Gy with a single dose of GBE (100 mg/kg) given one hour before irradiation, and 62.2 (59.1-65.5) Gy with two doses of GBE given at 25 hours and one hour before irradiation. The hypoxic cell fractions, estimated from $TCD_{50/120's}$, were $10.6{\%}$ under air breathing condition, $7.2{\%}$ after a single dose of GBE, and $2.7{\%}$ after two doses of GBE. The results of $^{31}P$ NMR spectroscopy were as follow. PCr/Pi ratio was $0.27{\pm}0.04$ and $0.40{\pm}0.04$ before and one hour after a single dose of GBE (p<0.05), respectively, without priming dose and $0.30{\pm}0.02$ and $0.71{\pm}0.04$, respectively, with priming dose (p<0.01). These findings indicate that the metabolic status is slightly improved after a single dose and markedly after repeated administrations. Conclusion : GBE decreases the hypoxic cell fraction and imprvoes the meta bolic status of tumor, probably by increasing the blood flow and delivery of oxygen and nutrients, resulting in increased radiosensitivity of tumor.

• Korean Journal of Food Science and Technology
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• v.36 no.4
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• pp.594-597
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• 2004

Effects of various levels and molecular weights (MWs) of chitooligosaccharides and chitosan with pork salt-soluble protein (SSP) on pH, moisture (%), viscosity, and hardness of protein-chitosan mixtures were determined in a model study. Mixtures of 0.15, 0.3, and 0.45% chitosan at various MWs (Low, 1.5 kDa; Medium, 30-50 kDa; High, 200 kDa) were dissolved in 3% SSP solution for measurement of pH and viscosity at $20^{\circ}C$. pH value increased with addition of 0.45% low MW of chitooligosacchearides into SSP (p<0.05), whereas decreased with addition of 0.45% medium MW and 0.3% or higher level of high MW chitosan. Viscosity increased with addition of more than 0.3% either medium or high MW chitosan (p<0.05), as compared to mixture with low MW chitolligosaccharide and control (p<0.05). No differences in gel pH, moisture, and hardness values were observed among treatments (p>0.05). Further study will be performed to evaluate rheological properties actual meat products with various levels and MWs of chitosan.

• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.513-520
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• 2020

Here, we evaluated the functional properties of histidine-containing low-molecular-weight (LMW) peptides obtained from tuna waste meats. As with histidine-related components composed of histidine, 1-methyl histidine and anserine, histidine-containing LMW peptides exhibited high α,α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging effect in a dose-dependent manner. Among the histidine-related dipeptides, anserine exhibited the highest reducing power followed by carnosine. By comparison with dipeptides, tuna extracts also showed similar reducing power and the activity was in a dose-dependent manner. In addition, the antioxidant activities of tuna extracts such as DPPH radical scavenging effect, reducing power, superoxide dismutase activities, and peroxide value of linoleic acid were affected by the various extraction methods.

• Applied Biological Chemistry
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• v.37 no.5
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• pp.326-333
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• 1994

Pleurotus florida with high cellulase activity as well as lignin degradability was selected out among strains for fermentation of the rice straw to improve the nutritive value. When the rice straw was fermented by P. florida, the contents of hemicellulose, cellulose and lignin were decreased to 22.5%, 11.4% and 28.1%, respectively, whereas the contents of rice straw fermented after pretreatment with $H_2O_2$ or alkaline hydrogen peroxide were decreased much in the lower concentration. The content of T-N (total-nitrogen) and crude fat was increased with the longer fermentation period. The amino acid content of rice straw fermented by P. florida in 30 days was increased to 28.9% and 35.1% as the rice straw was fermented after pretreatment without and with 4% $H_2O_2$, respectively. The crystalline intensity of rice straw was decreased by pretreatment with 4% $H_2O_2$ and fermentation by P. florida. However, the crystall intensity was increased by treatment with alkaline hydrogen peroxide and the more when the straw was washed after the treatment. When the rice straw was fermented by P. florida for 30 days, the in vitro organic matter digestibility was increased up to 6% of $H_2O_2$ pretreatment.

• Journal of Yeungnam Medical Science
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• v.1 no.1
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• pp.101-106
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• 1984

Before beginning the extracorporeal circulation, perfusionists should supply oxygen into the oxygenator and establish blood flow through the blood line of the heart-lung machine. But these manipulation can induce severe hypocarbic state of priming solutions due to wash out of $CO_2$ gas in the solution. This study was carried out to examine the relationship of blood gas changes between hypocarbic priming solutions and body circulation in 15 patients undergoing open heart surgery with extracorporeal circulation. $PaCO_2$, pH, buffer base and $PaO_2$ were measured from priming solutions before and 15 minutes after the extracorporeal circulation. The results were as follows; 1) Before the extracorporeal circulation, mean $PaCO_2$ level was $12.1{\pm}7.8mmHg$ in the priming solution. However, 15 minutes after extracorporeal circulation, the $PaCO_2$ level was maintained at $35.7{\pm}5.7mmHg$. 2) pH in the priming solution was variable from 6.93 to 7.99 (mean $7.45{\pm}0.29$), but after 15 minutes it was ranged from 7.28 to 7.42 (mean $7.35{\pm}0.05$). 3) Mean buffer base level in the priming solution was $7.9{\pm}3.5mmol/l$, but after 15 minutes, it was $19.6{\pm}1.2mmol/l$. 4) Mean $PaO_2$ level in the priming solution was $667.1{\pm}45.6mmHg$, but after 15 minutes, it was $280.7{\pm}131.7mmHg$.