• Title/Summary/Keyword: 내산성

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An Experimental Study on the Acid-Resistance of Concrete ―Focused on concrete with silica sand particles (콘크리트 내산성에 관한 실험적 연구-규사 분말 치환 콘크리트를 중심으로-)

  • 윤보현;부척량
    • Magazine of the Korea Concrete Institute
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    • v.9 no.5
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    • pp.127-135
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    • 1997
  • This paper is an experimental study of the acid-resistance of concrect which contains silica sand particles. In the concerete sample experiment. the workability and strengh as well as the acid-resistance of the hardended concrect is inverstigated.

The Effects of Additives and Fabrication Methods on Durability in Acid of Glass Frit for Thick Film Paste (후막페이스트용 Glass Frit의 내산성에 미치는 제조방법 및 첨가제의 영향)

  • 장규철;노태형;구본급;임대영;김호기
    • Journal of the Microelectronics and Packaging Society
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    • v.7 no.2
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    • pp.29-36
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    • 2000
  • The effects of additives and fabrication methods of glass frits far thick film paste on durability in acid of glass frits fur thick film paste were studied. To investigate the effect of fabrication method, glass brit based on $PbO-SiO_2-B_2O_3$ was prepared by various mixing method and number of melting. The effects of addition of $ZrO_2$, $Al_2O_3$, and $TiO_2$in glass on the durability in acid solution were investigated.

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Study on the corrosion resistance of coating mixture to acid for the desulfurization system (탈황설비용 탄소강 코팅조성물의 내산성에 관한 연구)

  • Kim, In-Ki;Ryu, Jeong-Koon
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.16 no.6
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    • pp.278-285
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    • 2006
  • Coating mixtures of the resin B-H for the application to the desulfurization system of power plant were coated on carbon steels and cured at the temperature of $65^{\circ}C{\sim}80^{\circ}C$. After being contacted with 70wt% $H_2SO_4$ solution of $100^{\circ}C\;and\;120^{\circ}C$ for several hours, their composition, Vicker's hardness and microstructures by SEM were examined. Corrosion resistance of the coating mixtures to $H_2SO_4$ solution was related to the content of $SO_3$ in the coated specimens after corrosion test. The lower curing temperature and the shorter curing time the coated specimens went through, the higher corrosion resistance to acid they showed, but the more cracks were developed at higher temperature. It was realized that the corrosion resistance to sulfaric acid solution was increased on the condition of curing temperature above $65^{\circ}C$ and curing time above 12 hours at least.

Studies on the Production of Acid Digestive Enzyme -Isolation and Characterization of a Fungal Strain Which Produces Acid Enzymes- (내산성(耐酸性) 소화효소제(消化酵素劑)의 생산(生産)에 관(關)한 연구(硏究) -내산성(耐酸性) 효소생산균(酵素生産菌)의 분리(分離)와 효소(酵素) 생산조건(生産條件)에 관(關)하여-)

  • Sohn, Cheon-Bae;Park, Yoon-Joong
    • Korean Journal of Food Science and Technology
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    • v.13 no.3
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    • pp.241-246
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    • 1981
  • A fungal strain which produced high levels of acid protease and amylase was isolated from the atmosphere for application to the manufacture of digestive enzme preparation. This study was carried out to elucidate its microbiological characteristics, environmental conditions for production of the enzymes, and relationships between the enzyme activity and acidity. 1. The isolate was identified as a fungal strain which belonged to Aspergillus niger by the manual of Rafer and Fennel, and was found to be a strain producing high levels of acid protease and amylase. 2. The optimal pH of tile enzymes produced by the strain were: protease, 2.0;, ${\alpha}-amylase$, 4 to 5; and glucoamylase, 3 to 5. 3. The optimal culture conditions for production of the enzymes were: protease (at pH 2.5), 2 to 3 days incubation on wheat bran at $30^{\circ}C$; ${\alpha}-amylase$ and glucoamylase(at pH 3.0), 3 days incubation at $30^{\circ}C$. 4. The production of acid protease and glucoamylase was increased approximately by 20 percent when 2 percent of corn starch was added to the wheat bran medium. 5. The addition of 0.3 percent ammonium sulfate to the wheat bran medium resulted in enhancing the enzyme production, especially of acid prctease.

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Isolation of Aspergillus niger K-25 Prroducing Acid-stable ${\alpha}-amylase$ (내산성(耐酸性) 아밀라제를 생산하는 Aspergillus niger 균주의 분리)

  • Cho, Myung-Hwan
    • The Korean Journal of Mycology
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    • v.17 no.3
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    • pp.149-153
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    • 1989
  • One strain of Aspergillus niger K-25 producing an acid-stable ${\alpha}-amylase$ was isolated from the soil. The optimum culture conditions were investigated. The production of the acid-stable ${\alpha}-amylase$ was enhanced when the strain was incubated in a medium containing soluble starch 3.5%, peptone 2%, $KH_2PO_4$ 0.5%, $MaSO_4{\cdot}7H_2O$ 0.25% and $FeCI_3$ 1.0% at pH 3 for 7 days. However, higher activity of acid-stable ${\alpha}-amylase$ was demonstrated on wheat bran culture. Amylase production was doubled when A. niger K-25 was incubated on the wheat bran supplemented with fumaric acid buffer (pH 3).

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Selection of Acid Tolerant Red Clover Cell Line on the Cellular Level II. Effect of some factors affecting suspension culture and acid tolerant cell selection (내산성 레드 클로-버의 배양세포수준에서의 선발 II. 레드 클로-버의 현탁배양 및 내산성 세포의 선발)

  • Son, Dae-Young-Son;Lee, Soon-Hee-Lee;Jo, Jin-Gi
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.13 no.1
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    • pp.1-6
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    • 1993
  • This experiment was conducted to select acid tolerant cells from red clover suspension culture and obtained following results. The most effective condition of plant growth regulators for suspension culture of red clover cells was 2 mg/l 2,4-D as auxin source plus 0.5 mg/l BAP as cytokinin source. Among serveral basal media, PC medium brought the best result. The most suitable EMS concentration for the mutated cells tolerant to acid was 1 % with fours treatment and average 27 colonies/plate were selected. The frequency of the occurence of mutants tolerant to acid in 1 % EMS with four hours treatment was 8.9 $\times$ 10$^{-5}$ which was 100 times larger than that of control. The total colonies selected initially were 176 but the survived colonies after two subcultures with 4 weeks interval in a selection medium were 44.

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The Study on Preparation and Characterization of Cool Ceramic Black Pigment (쿨 세라믹 블랙 안료의 제조 및 특성 연구)

  • Kwon, Myon-Joo;Ha, Jin-Wook
    • Proceedings of the KAIS Fall Conference
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    • 2012.05a
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    • pp.340-343
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    • 2012
  • 본 연구는 적외선 반사율 특성을 갖는 세라믹 블랙안료의 개발이며, 기능성안료를 건축내외장재에 적용하여 도심열섬현상 방지 및 에너지 효율을 높이는데 목적을 두고 있다. 세라믹안료의 색상은 Black을 합성하였으며, 각각 적외선 반사율과 내산성, 내열성 시험을 하여 색상변화를 측정하였다. 태양에너지의 측정파장영역 190~2000nm에서 TSR은 35.27%로 나타났으며, 내산성 시험 및 내열성 시험의 결과 거의 변색되지 않은 것을 알 수 있었다.

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Comparative Tests on the Acid Tolerance of Some Lactic-Acid-Bacteria Species Isolated from Lactic Fermented Products (젖산 발효제품에서 분리한 유산균의 내산성 비교)

  • Sim, Jae-Hun;Oh, Se-Jong;Kim, Sang-Kyo;Baek, Young-Jin
    • Korean Journal of Food Science and Technology
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    • v.27 no.1
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    • pp.101-104
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    • 1995
  • We isolated sixty lactic acid bacteria(LAB) from lactic fermented products. Among 60 isolates of LAB, 30 isolates were identified as Lactobacillus casei ssp.(5 strains), Lactobacillus acidophilus(2 strains), Lactobacillus delbrueckii ssp. bulgaricus(6 strains), Lactobacillus plantarum(4 strains), Streptococcus salivarius ssp. thermophilus(11 strains), and Streptococcus faecalis(2 strains). The acid tolerance and bile resistance of 30 LAB were determined. Because the acid tolerance was affected by the initial cell concentrations, the analysis of covariance could be used to remove the effect of initial cells on acid tolerance when testing for differences in acid tolerance among six species. Viability of LAB under acidic condition, pH 3 for 2 hours at $37^{\circ}C$, was significantly different among the species. L. casei and L. acidophilus strains showed great viability, but L. bulgaricus and S. thermophilus strains were very weak in acid tolerance.

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Studies on Acid-stable Alpha-amylase (내산성 ${\alpha}-Amylase$에 관한 연구)

  • Kim, Hack-Joo;Byun, Si-Myung
    • Applied Biological Chemistry
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    • v.21 no.2
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    • pp.103-108
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    • 1978
  • Acid-stable ${\alpha}-amylase$ was partially purified from Paecilomyces subglobosum by Sephadex G-150 gel filtration. About 7.7-fold purification was obtained and the partially purified preparation has 5.0 U of ${\alpha}-amylase$ activity per mg of protein. Using this partially purified ${\alpha}-amylase$, general properties were studied and it showed the maximal activities at the conditions of pH 4.0 and $38^{\circ}C$. High stability of the acid-stable ${\alpha}-amylase$ in acidic condition was observed, whereas thermal stability was similar to the conventional ${\alpha}-amylase$.

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Stability and Gastric Acid Resistance of Lactobacilli and Bifidobacteria in Commercial Yogurts (시판 요구르트 중 Lactobacilli 및 Bifidobacteria의 안정성 및 내산성 연구)

  • 이범진;박옥선;고준수;안태석;박승용
    • Korean Journal of Microbiology
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    • v.35 no.1
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    • pp.89-93
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    • 1999
  • Stability and gastric acid resistance of Lactobacilli and Bifidobacteria in commercial yogurts were invcstigated. It was noted that there was significant differences of stability and gastric acid resistance among yo-wts. The sutvival of Lactobacilli and B#idohacleria in commercial yogurts decreased as a function of time during storage and showed in the range of $10^7$-$10^8$ cfulml. The lower the pH was, the lower survival of Lactobacillus and B~dobaclerium was observed. The survival of Lactobacillz and Bifidobacteria in three yogurts appeared to be $10^3$-10$^4$ cfuIml. In the case of yogurt containing Bifidobncterza- loaded capsules, the gastric acid resistance of the Rifidobncteria was greatly enhanced and the survival after treatment in a gastric juice for 120 min was over 10' cfulml.

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