• Bulletin of the Korean Chemical Society
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• 제11권1호
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• pp.49-54
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• 1990

The gas-phase thermolysis reactions of ${\alpha}$- and ${\beta}$-methylated ethyl formates, Y = $CH-X-CHR_1CH_2R_2$ where X = Y = O or S and $R_1\;=\;R_2$ = H or $CH_3$, are investigated theoretically using the AM1 method. The experimental reactivity order is reproduced correctly by AM1 in all cases. The thermolysis proceeds through a six-membered cyclic transition state conforming to a retro-ene reaction, which can be conveniently interpreted using the frontier orbital theory of three-species interactions. The methyl group substituted at $C_{\alpha}\;or\;C_{\beta}$ is shown to elevate the ${\pi}$-HOMO of the donor fragment (Y = C) and depress the ${\sigma}^{\ast}$-LUMO of the acceptor fragment ($C_{\beta}$-H), increasing the nucleophilicity of Y toward ${\beta}$-hydrogen which in turn increases the reactivity. The two bond breaking processes of the $C_{\alpha}$-X and $C_{\beta}$-H bonds are concerted but not synchronous so that the reaction takes place in two stages as Taylor suggested. The initial cleavage of $C_{\alpha}$-X is of little importance but the subsequent scission of $C_{\beta}$-H occurs in a rate determining stage.

• Bulletin of the Korean Chemical Society
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• 제16권2호
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• pp.112-120
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• 1995

The conformational study on malonic acid, hydrogen malonate, malonate, malonyl methyl sulfide, and malonyl methyl sulfide anion, as the model compounds of malonyl-CoA, was carried out using the semiempirical MO methods (MNDO, AM1, and PM3) and hydration shell model. On the whole, the feasible conformations of malonic acid, hydrogen malonate, and malonate seem to be similar to each other. In malonic acid and malonate, two carboxyl groups are nearly perpendicular to the plane of the carbon skeleton, despite of different orientation of two carboxyl groups themselves. In particular, two carboxyl groups of hydrogen malonate are on the plane formed by carbon atoms with an intramolecular hydrogen bond. The calculated results on the geometry and conformation of three compounds are reasonably consistent with those of X-ray and spectroscopic experiments as well as the previous calculations. The orientation of two carbonyl groups of malonyl methyl sulfide is quite similar to that of malonic acid, but different from that of its anion. Especially, the computed probable conformations of the sulfide anion by the three methods are different from each other. The role of hydration seems not to be crucial in stabilizing the overall conformations of malonic acid, hydrogen malonate, malonate, and malonyl methyl sulfide. However, the probable conformations of the unhydrated sulfide anion obtained by the MNDO and AM1 methods become less stabilized by including hydration. The AM1 method seems to be appropriate for conformational study of malonyl-CoA and its model compounds because it does not result in the formation of too strong hydrogen bonds and significant change in conformational energy from one compound to another.

• 약학회지
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• 제38권5호
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• pp.496-503
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• 1994

The combined products of antacids(AM) composed of aluminium hydroxide, magnesium hydroxide, and simethicone with a ratio of 1 : 1 : 0.1 and aceglutamide aluminium(AGA) were assayed for the antiulcer activity. The effect of the antacids(AM) in concurrent treatment with AGA was studied in acute gastric lesion induced by Shay's method, stress, ethanol, and indomethacin, in chronic gastric ulcers induced by acetic acid, and in duodenal ulcer induced by mepirizole. In all experimental models, the combined treatment of AM and AGA in the ratio of 2.3:1 showed significant potentiation in inhibition against acute gastric and duodenal ulcer and revealed a significant potentiation of the healing of chronic gastric ulcer.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.139-148
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• 2003

In this study, biodegradable base Li-greases were prepared by using Li-soap thickener and vegetable oils such as soybean oil, rapeseed oil, castor oil and synthetic ester. Also, EP-greases were formulated by blending base Li-greases, anti-wear additives, EP additives, anti-oxidants and corrosion inhibitor etc. And EP-greases were characterized by analysing physical properties such as worked penetration, dropping point, 4-ball wear, extreme pressure, thermal properties etc. Biodegradability of base Li-greases and EP-greases were evaluated by CEC-L-33-A-93 method using several inoculums of domestic sewage treatment plant. As the results, biodegradability of vegetable oils were shown at the range of 97.1 to $98.4\%$. And biodegradability of base Li-greases and EP-greases were $86.2\%\;\~\;89.3\%\;and\;83.4\%\;\~\;90.0\%$ which were lower value than those o( vegetable oils due to effect of Li-soap thickener, respectively. Therefore, the EP-greases prepared in this study were easily biodegraded by microorgnism.

• Applied Microscopy
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• 제43권1호
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• pp.1-8
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• 2013

We developed an improved method for tilt series alignment with fiducial markers in electron tomography. Based on previous works regarding alignment, we adapted the Levenberg-Marquardt method to solve the nonlinear least squares problem by incorporating a new formula for the alignment model. We also suggested a new method to estimate the initial value for inversion with higher accuracy. The proposed approach was applied to geopolymers. A better alignment of the tilt series was achieved than that by IMOD S/W. The initial value estimation provided both stability and a good rate of convergence since the new method uses all marker positions, including those partly covering the tilt images.

• 한국양식학회지
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• 제11권1호
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• pp.91-97
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• 1998

이 연구에서는 해산어의 종묘 생산에 필요한 대량 배양용 로티퍼, Brachionus rotundiformis의 종 보존 방법으로서 무균 로티퍼의 이용을 검토했다. 로티퍼는 개량형 항생제 혼합액 AM9을 사용하여 무균 처리한후, 무균 Nannochloropsis oculata를 먹이로 공급하여 연속 유지 배양했다. 각각 다른 시기의 3회 (trial 1, 2 and 3)에 걸친 로티퍼 배양결과, 무균 배양 (axenic culture)에서는 비교적 안정적인 증식을 보인 반면, 유균 배양 (non-axenic culture)에서 로티퍼의 증식은 불안정적으로 각 시기에 따라서 심한 증식의 차이가 관찰되었다. 이 결과는 유균 배양에서 로티퍼의 증식에 직접적으로 악영향을 미치는 박테리아가 무균 처리과정을 통해서 제거되었음을 증명한다. 로티퍼 무균 배양 방법의 일반화 또는 대량 배양용 로티퍼의 씨앗으로서의 무균 로티퍼의 이용은 로티퍼의 안정 배양은 물론 유용 수산 생물의 대량 폐사를 일으키는 원인 생물을 사전에 제거할 수 있는 유효한 방법이 될 수 있다고 생각된다.

• 기본간호학회지
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• 제18권4호
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• pp.472-479
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• 2011

Purpose: The purpose of this study was to develop guidelines for cleaning of enteral nutrition bags by comparing the level of equipment contamination according to cleaning and disinfection methods. Method: This study was a true-experimental study, with 60 cases in total. Twenty cases each were randomly assigned to tepid water, detergent and brush, and disinfectant groups. The period of the experiment was March to April 2010, and enteral nutrition was given for 1 houre, 3 times a day at 7AM, noon, and 7PM for seven days. Enteral nutrition bags were cleaned after each feeding according to assigned cleaning and disinfection method followed by microbial cultures on 4th and 8th day before the 7AM feeding. Results: After 3 days of feeding and cleaning, the level of contamination of bags was not significantly different among the three groups. After seven days, the level of contamination was significantly lower when bags were cleaned with detergent and brush or with disinfectant compared to cleaning with tepid water. Conclusion: In cases where enteral nutrition bags are reused for example, in home care settings, studying findings indicate that cleaning bags using detergent and brush or disinfectant is an effective way to prevent contamination of bags.

• 기본간호학회지
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• 제6권1호
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• pp.7-17
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• 1999

This study investigated the degree of knowledge achievement and self-confidence in aseptic technique as a part of the fundamental nursing practice classes. The subjects were 220 nursing students in a junior college in Chonnam and an applied Quasi-experimental research methodology was used thirty of them comprised an experimental group to examine learning according to the teaching method. Wata were collected over 80 days, from April to June 1988, analyzed using descriptive statistics, percentages, means, t-test, one way ANOVA, Pearson's correlation coefficient and stepwise multiple regression with the SAS program. The conclusions are as follows. 1. The mean score of the degree of knowledge achievement of aseptic technique of the 220 students was 0.68(possible score 1.0) before the lecture but was 0.88 after lecture(p=.000). 2. The mean score for aseptic technique of the 220 students was 3.41(possible score 5.0) before practice but was 4.27 after practice(p=.000). 3. The correlation of self-confidence before and after practice was relatively low(r=.25, p=.000). 4. The mean score of the degree of knowledge achievement of aseptic technique in the experimental group(selected 30 students) was 0.72 before the lecture but was 0.90 after the lecture. 5. The mean score of self-confidence on aseptic technique in the experimental group(selected 30 students) was 3.18 before practice but was 4.32 after practice(p=.000). 6. The mean score of learning according to the type of teaching to aseptic technique for the experimental group(selected 30 students) was 23.2(possibel score 34) after lecture and presentation, was 27.3 after learning through video tape, was 31.7 after presentation through practice, was 33.7 after first practical training, and was 34 after secondary practical training. As a result of this study, learning methods in the education of fundamental nursing skill effective for knowledge achievement and competence in practicing skill.

• 한국재료학회지
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• 제16권8호
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• pp.516-523
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• 2006

In recent years, Magnesium (Mg) and its alloys have become a center of special interest in the automobile industry. Due to their high specific mechanical properties, they offer a significant weight saving potential in modern vehicle constructions. Most Mg alloys show very good machinability and processability, and even the most complicated die-casting parts can be easily produced. The die casting process is a fast production method capable of a high degree of automation for which certain Mg alloys are ideally suited. In this study, step-dies and flowability tests for AM50 were performed by die-casting process according to various combination of casting pressure and plunger velocity. We were discussed to velocity effect of forming conditions followed by results of microstructure, FESEM-EDX, hardness and tensile strength. Experimental results represented that the conditions of complete filling measured die-casting pressure 400 bar, 1st plunger velocity 1.0 m/s and 2nd plunger velocity 6.0 m/s. The increasing of 2nd plunger velocity 4.0 to 7.0 m/s decreased average grain size of $\alpha$ phase and pore. It was due to rapid filling of molten metal, increasing of cooling rate and pressure followed by increased 2nd plunger velocity. The pressure should maintain until complete solidification to make castings of good quality, however, the cracks were appeared at pressure 800bar over.

• 미생물학회지
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• 제43권1호
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• pp.31-39
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• 2007

2000-2004년 국내에서 분리된 S. sonnei 135주를 선별하여 16종의 항균제 내성 유형, $bla_{TEM}$, suulII, tetA, strA등의 내성유전자형을 PCR등의 방법으로 항생제내성 표현형과 유전자형의 유연관계를 파악하였다. 균주들의 생화학적 성상은 전형적 인 이질성 세균의 특성을 나타내었으며, biotyping에서는 g type이 58.5%(79주), a type이 40.0%(54주), e type이 1.5%(2주)로 나타났다. 항균제 16종의 항균제 내성 패턴은 AN, CIP, C, GM등의 약제에는 감수성을 보였으나, SXT 약제에는95.6% (129주), TE 약제에는 93.3% (126주), SM에는 90.4% (122주)등의 순으로 내성을 나타내었다. 두 가지 이상 약제 내성균이 97.8% (132주), 그 중에서 R28 (AM, SAM, TE, TIC, SXT, K, SM, AmC : 8제 약제 내성) 형이 31.1% (42주)를 차지하였으며, 33가지 형태의 다양한 내성 패턴을 나타내었다. $bla_{TEM}$, sulII, tetA 및 strA등의 내성유전자 분포에서는 Disk diffusion법에서 내성을 보인 경우에는 모두 각각의 유전자 증폭산물이 검출되었다.