• 산업기술연구
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• 제21권A호
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• pp.17-26
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• 2001

The fatigue strength of SM55C has significantly decreased by 83% compared with atmosphere where distilled exists due to strong erosive action of acid fog. The reason is inferred in a way that strong acid erosive material such as acid fog act and give rise to multi-site crack on the surface. Several fatigue clacks occurred under the acid fog repeat the process of division and unification on the surface and form a long non-propagating crack throughout the circumference of experimented steel. However, in the depth, many parts do not show much trace of unification, and the depth is not as big as the one of normal crack shape. 10% of $CaCl_2$ causes strong erosive reaction to material. Then eventually make the life of fatigue shooter. On the other hand, 20% of $CaCl_2$ beings about oxidized material organic crack closing due to weak erosive reaction.

• 대한화학회지
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• 제56권5호
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• pp.628-637
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• 2012

이 연구에서는 1945년 교수요목기의 교과서부터 2009 개정 교육과정 화학II 교과서까지 수용액에서 강산의 이온화도에 대한 내용을 분석하고, 현직 화학 교사 50명을 대상으로 수용액에서 강산의 화학종에 대한 인식과 이온화도를 고려하였을 때의 인식 차이를 알아보는 설문과 면담을 실시하였다. 연구 결과, 우리나라 교사들은 교과서에 제시된 이온화도 값을 근거로 강산의 수용액 안에 존재하는 화학종에 대한 생각을 하고 있었으며, 강산의 정의와 교과서에 제시된 이온화도 값이 서로 일치하지 않은 문제를 생각하지 못하거나, 문제를 인식하는 경우에도 그에 대한 해결을 하지 못한 것으로 나타났다.

• 한국대기환경학회지
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• 제10권4호
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• pp.281-288
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• 1994

The hydrodesulfurization (DBT) were Peformed over NiPtMo catalysts supported on HZSM-5, LaY and ${\gamma}$- $Al_2$O$_3$under high H$_2$ pressure. And the acidities of these catalysts were characterized by using TGA and DSC. The result showed that the order of the acid strength for prepared supports was HZSM -5＞LaY＞${\gamma}$- A1$_2$O$_3$. For the acid amount we obtained the same result for the acid strength The acid strength and the acid amount mainly depended on the kinds of supports whose acid site were strong or not The activity of the hydrodesulfurization decreased for catalysts which had strong acid sites. The origin of acid site was Bronsted in NH50 and NY catalysts And it was Lewis in NA catalyst The order of desorption activation energy for Pyridine was NH50＞NY>NA. And the result was the same for thiophene. The activity of the hydrodesulfurization decreased for catalysts which had strong acid sites. The conversion of DBT over NA catalyst was higher than NH and NY catalysts.

• 대한화학회지
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• 제59권3호
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• pp.238-245
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• 2015

The crystallization and morphology change of amorphous titanias by hydrothermal treatment have been investigated. The amorphous titanias were prepared by pure water hydrolysis of two different precursors, titanium tetraisopropoxide (TTIP) and TTIP modified with acetic acid (HOAc) and characterized prior to hydrothermal treatment. In order to avoid complicate situation, the hydrothermal treatment was performed in a single solvent water with and without strong acids at various temperatures. The effects of strong acid, temperature and time were systematically investigated on the transformation of amorphous titania to crystalline TiO₂ under simple hydrothermal condition. Without strong acid the titanias were transformed into only anatase phase nanoparticle regardless of precursor type, temperature and time herein used (up to 250 ℃ and 48 hours). The treatment temperature and time effected only on the crystalline size, not on the crystal phase et al. However, it was clearly revealed that the strong acids such as HNO₃ and HCl catalyzed the formation of rutile phase depending on temperature. HCl was slightly better than HNO₃ in this catalytic activity. The morphology of rutile TiO₂ formed was also a little affected by the type of acid. The precursor modifier, HOAc slightly reduced the catalytic activity of the strong acids in rutile phase formation.

• Journal of Plant Biology
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• 제34권4호
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• pp.325-330
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• 1991

The ability of several auxin analogs to induce ethylene production was tested in the corn coleoptile. The synthetic auxins 1-naphthaleneacetic acid (1-NAA) and 2, 4-dichlorophenoxyacetic acid (2, 4-D) had strong stimulatory effects on ethylene induction surpassing that of IAA. Both 2-naphthalaneacetic acid (2-NAA) and 2, 6-dichlorophenoxy acetic acid (2, 6-D), structural analogs of these auxins, respectively, were found to be inactive. Treatment with NPA, a strong inhibitor of polar auxin transport, led to drastic increase in IAA-induced ethylene production while it has bo effect on ethylene production induced by 1-NAA. A positive correlative existed between intracellular auxin level and ethylene production.

• 한국환경보건학회지
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• 제5권1호
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• pp.21-24
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• 1978

This study was conducted to find out the co-operative effect of antioxidants (butyl hydroxy anisol, dibutyl hydroxy toluene, propyl gallate, dl-$\alpha$-tocopherol) and organic acid (citric acid, tartaric acid, succinic acid) on the stability of soybean oil by active oxygen method. The results obtained were summarized as follows: 1. When antioxidants and organic acid were used together, the antioxidants activity was more strong than antioxidants were used only. 2. The co-operative effect of citric acid for antioxydants was the strongest whereas succinic acid was the weakest. 3. The co-operative effect of phenolic antioxydants for organic acid was more strong than dl-$\alpha$-tocopherol.

• 한국식품저장유통학회지
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• 제7권1호
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• pp.103-107
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• 2000

Previously , the methanolic extract of peach sees was found to have a strong tyrosinase inhibitory activity in an in vitro assay. Several phenolic compunds were isolated from the seeds by solvent fractionation , Sephadex LH-20 chromatography, and preparative HPLC , and one of them showing strong tyrosinase inhibition was identified as benzoic acid by UV, IR, $^1$H/$^1$$^3$C-NMR, and EI-MS spectrsopy. Benzoic acid (IC50= 250$\mu\textrm{g}$/ml) and L-ascorbic acid (IC50=28$\mu\textrm{g}$/ml), well-known tyrosinase inhibitors. In particular , benzoic acid inhibited markedly the enzymatic browing (melanosis) of apple juices at low concentration of 0.01% and 0.05, comparable to that of L-ascorbic acid (P<0.05). these results suggest that benzoic acid, one of an effective food preservatives, may be potentially useful as a functional alternative to sulfites for the control of melanosis in fruit juices.

• 한국미생물·생명공학회지
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• 제1권2호
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• pp.99-104
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• 1973

A study on the active center of the acid protease from Penicillium sp. was conducted, and also the milk clotting activity of acid prorease was measured. 1. PCMB failed to influence the proteolytic activity of acid protease, indicating that a reactive sulfhydryl group is not required for the enzymatic activity. 2. $\varepsilon$-amino caproic acid did not show any inhibitory effect on tile proteolytic activity of acid protease. 3. Also 2, 4-dinitro phenol did not show any inhibitory effect on the enzyme activity. 4. Acid protease from Penicillium sp. showed a strong milk clotting activity in the presence of Ca ion. 5. This enzyme had a strong proteolytic activity on various substrate, such as casein, denatured hemoglobin, ovalbumin, denatured bovine muscle protein, denatured percine muscle protein and denatured chicken muscle protein.

• 한국응용과학기술학회지
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• 제6권2호
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• pp.59-65
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• 1989

The rate constants of the hydrolysis of cinnamanilide derivatives were determined UV spectrometry in $H_2SO_4\;(5{\sim}20N)$, NaOH($5{\sim}11N)\;at\;50{\sim}110^{\circ}C$ and rate equation could be applied over a strong acid and strong base were obtained. Final product of the hydrolysis was a cinnamic acid. The ${\rho}$ values obtained from the slope of linear plots of log $k_{abs}$ vs. Hammet $t{\sigma}$ constants were slightly negatives, Substituents on cinnamanilide showed a relatively small effect, with hydrolysis facilitated be electron donating group. Activation energy(Ea)was also calculated for the hydrolysis of the cinnamanilide. From this reaction rate equation, substituent effect and experimental of rate constants, that the hydrolysis of cinnamanillde was Initiated by the netural molecule of $H_2O$ which do not dissociate at strong acid, and proceeded by hydroxide ion at strong base.

• Ocean and Polar Research
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• 제35권4호
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• pp.273-280
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• 2013

The proximate composition, free amino acid composition and mineral contents from Undariopsis peterseniana were determined, and the antioxidant activities of ethanol (EtOH) and hot water extracts of U. peterseniana were investigated using DPPH (1,1-diphenyl-1-picrylhydrazyl), ABTS (2,2'- azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) radical scavenging effects and reducing power. The contents of moisture, ash, protein, lipid and carbohydrate were 12.5%, 23.1%, 9.7%, 0.2% and 54.5%, respectively, and alginic acid content was 12.3%. The major free amino acid contents were alanine, phenylalanine, aminoethanol, valine, glutamic acid and phosphoserine. Ca (1589.1 mg) was the largest mineral followed by Na (344.6 mg), Mg (74.3 mg), Zn (10.2 mg) and Fe (1.5 mg). The total phenolic contents of EtOH and hot water extracts were exhibited at 15.7 and 4.3 mg GAE/g sample, respectively. The antioxidant activity of EtOH extract exhibited strong ABTS and DPPH radical scavenging activities with reducing power, and hot water extract also demonstrated strong ABTS radical scavenging effects. Therefore, the results of this study suggest that U. peterseniana contained an abundance of naturally occurring nutrients (free amino acids and minerals), and the strong antioxidant activities of EtOH and hot water extracts from U. peterseniana could be good sources of natural antioxidants for healthcare products.