• 대한통합의학회지
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• 제6권3호
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• pp.131-139
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• 2018

Purpose : The study objective was to assess the antibacterial activity of essential oil of basil against S. mutans and P. gingivalis and to explore its potential to prevent dental caries and peridontal disease. Method : Essential oil of basil, extracted using steam distillation, was diluted with triple distilled water and Tween 20 to generate samples at various concentration, that is 30%, 50%, and 70% (v/v). Strains of S. mutans and P. gingivalis were incubated in the medium under anaerobic condition. Broth microdilution susceptibility testing and plate incubation diffusion were utilized to determine the minimum inhibitory concentration (MIC) and to measure antibacterial activity, respectively. Result : An upsurge in antibacterial activity was seen to correlate with and increase in the concentration used for both bacterial strains, but was more significant with S. mutans. A statistically significant growth inhibition effect and reduction in the number of colonies was also observed with both strains dependent on the concentration used following 24 hours of incubation. Conclusion : Thus, the current study finding was that essential oil of basil was effective against dental caries and periodontal disease and could be used in dentifrice to help prevent oral disease.

• 대한기계학회논문집
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• 제10권3호
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• pp.292-297
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• 1986

본 연구에서는 2024 Al 합금에 대하여 260-380.deg. C의 온도 범위 및 2~5kgf/ m $m^{2}$의 부과응력 범위에서 실시한 고온 정상 크리이프 변형 중의 내부응력 .sigma. $_{i}$,의탄성 변형 .epsilon.$_{A}$ 및 회복율 r의 측정 실험을 통하여 이들 상호간의 관계 를 살펴 보고자 한다.다.다.

• Applied Biological Chemistry
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• 제13권2호
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• pp.131-151
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• 1970

A new method of plastic film coating has been investigated to extend storage life of apples. The film coating was effected by dipping fresh apples in a plastic emulsion. The effect of plastic film coating on the preservation of freshness, respiratory activities and chemical components during storage, has been investigated on four leading varieties of apples. The results are summarized as follows: 1. The effect of film coating on storage life of apples was apparent, resulting in delay of after-ripening, shriveling, softening or physiological impediment as well as reducing consumption of reserve materials and waste fruits. 2. Change in the partial pressure of gas, i.e., increase in carbon dioxide and decrease in oxygen in apple tissue was resulted by the plastic film coating, suggesting that the film deposited on the fruit interfered with the diffusion of gases formed therein. 3. The effects of plastic film coating on the fruit storage varied with the type of plastic emulsions, coating temperature, varieties of apples and degree of fruit ripening. As regard to apple varieties, good results were obtained with PVA 217 for both American Summer Pearmain and Jonathan, and PVC 443 for McIntosh. 4. Reduction in the diminution rates of L-malic acid, ascorbic acid and soluble pectin etc. during storage of apples may account for the improved storage life of the fruits treated with plastic films.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.694-699
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• 2002

In autobody assembly, thin-wall, tubular connections have been used for the frame structure. Recent interest in light materials, such as aluminum or magnesium alloys, has been rapidly growing for weight reduction and fuel efficiency. Due to higher thermal expansion coefficient, low stiffness/strength, and low softening temperature of aluminum and magnesium alloys, control of welding-induced distortion in these connections becomes a critical issue. In this study, the material sensitivity to welding distortion was investigated using a T-tubular connection of three types materials; low carbon steel (A500 Gr. A), aluminum alloy (5456-H116) and magnesium alloy (AZ91C-T6). An uncoupled thermal and mechanical finite element analysis scheme using the ABAQUS software program was developed to model and simulate the welding process, welding procedure and material behaviors. The predicted angular distortions were correlated to the cumulative plastic strains. A unique relationship between distortion and plastic strains exists for all three materials studied. The amount of distortion is proportional to the magnitude and distribution of the cumulative plastic strains in the weldment. The magnesium alloy has the highest distortion sensitivity, followed by the other two materials with the steel connection having the least distortion. Results from studies of thin-aluminum plates show that welding distortion can be minimized by reducing the cumulative plastic strains by preventing heat diffusion into the base metal using a strong heat sink placed directly beneath the weld. A rapid cooling method is recommended to reduce welding distortion of magnesium tubular connections.

• 한국환경보건학회지
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• 제37권2호
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• pp.133-140
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• 2011

Antimicrobial activity and bactericidal activity of Caesalpinia sappan L. extracts were investigated against five food-borne pathogens, E. coli, S. aureus, S. typhimurium, B. cereus and L. monocytogenes. Methanol extract of Caesalpinia sappan L. revealed antimicrobial activities against five pathogens. In particular, by paper disc diffusion the highest activity was shown against L. monocytogenes. Antimicrobial activities of methanol extracts showed the most potent activities, but hexane fraction had no activity. Fractions of ethyl acetate and butanol turned out to have higher antimicrobial activities against Gram(+) bacteria than Gram(-) bacteria. The minimum inhibitory concentration against five food-borne pathogens was 1.563 mg/ml on Gram(+) bacteria and 3.125 mg/ml on Gram(-) bacteria. The result of antimicrobial activity in a shaking flask method showed that bacterial growth rate fell by more than 99.999% at 3.125 mg/ml of methanol extract. The highest rate of viable reduction (99.998%) was shown at 0.781 mg/ml of methanol extract against L. monocytogenes. After five minutes of reaction between test strains and methanol extracts, the growth rates of five kinds of bacteria were reduced by more than 99.999% at a concentration of 100 mg/ml. Therefore, it is suggested that methanol extracts of Caesalpinia sappan L. can be developed as a natural sanitizer or disinfectant.

• 한국동물위생학회지
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• 제30권3호
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• pp.363-374
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• 2007

A biochemical characterization and antimicrobial drugs susceptibility study was conducted in four breeding kennel which was canine abortion caused by Brucella canis in Gyeongbuk province in 2003-2006. Total of 267 dogs domesticated in the four kennel were examination. Among them, 143 (53.6%) dogs were sero-positive and 25 of blood samples were isolated to Brucella canis. At amplification of 35KDa-BCSP gene using PCR, 711 bp DNA fragment was same visible in 25 isolates and B canis RM6/66. Biochemical characterization of B canis isolated was non-hemolytic, no production of $H_2S$, no fermentation of carbohydrates, catalase-positive, oxidase-positive, indol-negative, hydrolyzation of urea, reduction of nitrate and development of thionin dye medium. Using disk-diffusion method, all of 25 strains tested were found to be highly susceptible to tetracycline, aminoglycoside, quinolone, macrolide antibiotics, rifampin and ampicillin in vitro. Using PFGE with restriction enzyme Smi I, 25 isolates tested were typed to 2 pattern, S1 and S2.

• 한국자기학회지
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• 제9권6호
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• pp.306-311
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• 1999

Water-based sol-gel 법으로 La2/3Sr1/3MnO3(LSMO)/YSZ/SiO2/Si(100) 다결정체 박막을 제조하여 YSZ 중간층 도입에 따른 상온, 120 Oe의 저 자장영역에서 측정한 tunnel-type 자기저항 변화에 미치는 영향에 대하여 고찰하였다. 페롭스카이트 단일상을 갖는 미세한 LSMO 박막을 얻을 수 있었으며, YSZ 중간층을 도입하지 않은 박막의 자기저항 변화비는 최대 약 0.20%이었으나, YSZ 중간층을 도입한 경우 자기저항비가 0.42%로 증가하였다. 이러한 tunnel-type 자기저항의 증가 현상은 YSZ 중간층이 SiO2/Si(100) 기판과 La2/3Sr1/3MnO. 자성박막 사이에서 확산 장벽층으로서의 역할을 수행하여 LSMO 박막의 미세구조 특성 향상 및 확산반응에 의하여 생성된 dead layer를 감소시켜 나타난 결과이다.

• 한국표면공학회지
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• 제36권1호
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• pp.9-13
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• 2003

Plasma polymerized organic thin films were deposited on Si(100), glass and metal substrates at $25∼100 ^{\circ}C$ using thiophene and toluene precursors by PECVD method. In order to compare physical and electrochemical properties of the as-grown thin films, the effects of the RF plasma power in the range of 30∼100 W and deposition temperature on both corrosion protection efficiency and physical properties were studied. We found that the corrosion protection efficiency ($P_{k}$), which is one of the important factors for corrosion protection in the interlayer dielectrics of microelectronic devices application, was increased with increasing RF power. The highest $P_{k}$ value of plasma polymerized toluene film (85.27% at 70 W) was higher than that of the plasma polymerized thiophene film (65.17% at 100 W), indicating inhibition of oxygen reduction. The densely packed and tightly interconnected toluene film could act as an efficient barrier layer to the diffusion of molecular oxygen. The result of contact angle measurement showed that the plasma polymerized toluene films have more hydrophobic surface than those of the plasma polymerized thiophene films.

• 한국식품저장유통학회지
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• 제4권1호
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• pp.17-25
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• 1997

The effects of microwave treatment on the perservation of foods, such as a seaweed soup and sea stoned radish shreds, were studied. Microwave treatment of microbial cell suspensions revealed that viable cells decreased dramatically when heated to 6$0^{\circ}C$. However, it was unlikely that microwave treatment to 60 is enough to decrease the viable cell counts efficiently in a seaweed soup and radish shreds. It was thought that microwave heating to at least 7$0^{\circ}C$ as a final temperature was an important factor to reduce microbial cell counts in foods. When foods were heated to 7$0^{\circ}C$ with a repetitive 15 sec "on" followed by 30 sec "off", no big differences were observed in viable counts during storage at 2$0^{\circ}C$ for 3 days, as compared to those treated with a full power. The microwave treatment with three stages was designed to solve problems associated with variations depending on food volumes and difficulties of heat diffusion in a solid food to be irradiated with a microwave oven. The three stage method was found to have a similar efficiency in the reduction of viable cell counts in foods to microwave treatment at a full power and to conventional methods, such as water bath heating or boiling for 3 min with a gas range.in with a gas range.

• Nuclear Engineering and Technology
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• 제51권6호
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• pp.1479-1486
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• 2019

The purpose of the present study is to develop the 3D static and noise simulator based on Galerkin Finite Element Method (GFEM) using the unstructured hexahedral elements. The 3D, 2G neutron diffusion and noise equations are discretized using the unstructured hexahedral by considering the linear approximation of the shape function in each element. The validation of the static calculation is performed via comparison between calculated results and reported data for the VVER-1000 benchmark problem. A sensitivity analysis of the calculation to the element type (unstructured hexahedral or tetrahedron elements) is done. Finally, the neutron noise calculation is performed for the neutron noise source of type of variable strength using the Green function technique. It is shown that the error reduction in the static calculation is considerable when the unstructured tetrahedron elements are replaced with the hexahedral ones. Since the neutron flux distribution and neutron multiplication factor are appeared in the neutron noise equation, the more accurate calculation of these parameters leads to obtaining the neutron noise distribution with high accuracy. The investigation of the changes of the neutron noise distribution in axial direction of the reactor core shows that the 3D neutron noise analysis is required instead of 2D.