• Analytical Science and Technology
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• v.9 no.3
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• pp.302-309
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• 1996

Fe-5.7%AI-1.1%Cr-0.5%Si damping alloys containing 0%C and 0.12%C were heat-treated at $800^{\circ}C$ for an hour and then cooled by using some different methods. The damping behaviors of these alloys were observed by optical microscopy, X-ray diffraction and a specific damping capacity(SDC) test. Effect of cooling method on microstructures and the internal stresses of these alloys were negligible while the damping capacity of these alloys was considerably deteriorated by water quenching. The (200) texture was mainly developed by water quenching while the (110) texture by furnace cooling. These results were interpreted by the magnetization behaviors of the ferromagnetic $\alpha$ ferrite. The easy axis of magnetization in <100> direction means that <100> axis has more $180^{\circ}$ magnetic domain walls than $90^{\circ}$ ones. Thus. $180^{\circ}$ magnetic domain walls were more formed by water quenching, which deteriorated the damping capacity of these alloys. Consequently, the amount of magnetic domain walls giving good damping capacity became less so that the damping capacity was poor in water quenching.

• Proceedings of the Korean Journal of Food and Nutrition Conference
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• 2000.05a
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• pp.5-7
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• 2000

국내에서의 식이섬유의 이용은 대부분 저분자량의 수용성 식이섬유를 이용한 음료형태가 주류를 이루고 있으며, 밀기울, 귀리, 옥수수 껍질 등으로 부터 얻는 불용성 식이섬유는 제과 및 제빵등에 이용되어 오고 있다. 수용성 식이섬유는 혈중 콜레스테롤을 저하시키며, 불용성 식이섬유는 변비예방과 장기능 증진효과가 탁월한 것으로 알려져 있다. 그러므로, 대장암과 변비같은 장질환 환자가 날로 증가하고 있는 상황에서 국내산 미이용 자원으로부터 불용성 식이섬유의 기능성 향상과 활용기술을 개발하는 것은 식품산업적 가치가 크다고 할 수 있다. 또한, 국내에서 소비되고 있는 폴리덱스트로스와 올리고당과 같은 기능성 당류의 대부분이 외국에서 수입하여 국내에 보급되고 있기 때문에 큰 외화지출이 되고 있다. 따라서 본고에서는 국내산 미곡 부산물인 밀기울 식이섬유 세포벽의 불용성 구조를 수용성으로 변화시킬 수 있는 변형기술과 얻어진 수용성 식이섬유 소재의 특성을 소개하고자 한다. 즉, 밀기울 세포벽의 수용화를 위한 가공처리는 압출성형 공정에 의하여 실시하였으며, 수용화가 수반되는 압출성형 조건에 따른 식이섬유 소재의 이화학적 특성과 수용화가 일어난 세포벽 성분의 분해기작에 대한 연구결과를 정리하였다. 그리고, 현행 올리고당과 식이섬유의 산업적 생산공정에서 문제점으로 대두되고 있는 효소처리, 산성하에서의 감압가열, 고점도 원료물질의 이송, 생물공학적 공정제어, 반응시간, 잔여 효소의 불활성화 및 재활용, 제조원가 상승 등과 같은 것을 해결하거나 개선할 수 있는 효율적인 압출반응공정의 조건과 생산된 소재 glucooligosaccharide, fructooligosaccharide, galactooligosaccharide 등의 특성에 대하여 논하여 보기로 한다.경우가 많지 않다. 또한 그 발생 경위나 원인요소에 대해서는 일반에게 공개되지 않고 있어, 우리가 실천하여 식중독을 예방할 수 있는 정보가 함께 제시되지 못하는 형편이다. 따라서 본 고에서는 최근 수년간 외국에서 학교급식을 비롯한 집단급식 등에서 발생한 식중독 사례를 중심으로 고찰, 분석하였다. 이로부터 식중독 발생에 기여한 주요 원인을 찾아내고 여기서 얻어지는 교훈을 토대로 식중독 발생을 예방 및 최소화할 수 있는 실천적 대처 방안을 모색해 보고자 한다.중의 E. coli O157:H7이 연관되어있다는 보고도 있다. 목장 방문시 원유를 마신 어린이에서 HUS가 유발하였고, 균분리 결과, 농장의 소와 어린이에서 유사한 E. coli O157:H7이 분리된 바 있다. 본 연자들은 베로톡신 유형, plasmid profiles, RFLP 분석, phage type을 기초로하여 소에서 분리된 E. coli O157:H7이 사람유래주와 매우 유사함을 확인하였다.mm 및 2-6mm 난포에서의 101개(67.8%) 및 47개(50.0%) 보다 매우 낮게 나타났다. 전체 회수 난포란수도 4등급이 59.1%(149/252)로써 1, 2, 3등급의 0.4% (1/252), 7.6%(19/252) 및 32.9%(83/252)보다 높게 나타났다. 1회 평균 회수 난포란은 $\leq$2mm 난포에서 4.8$\pm$3.7개로써 2-6mm(3.0$\pm$3.4개) 및 $\geq$6mm (0.3$\pm$0.6개)보다 높았으며, 1회당 평균 8.1$\pm$5.1개의 난포란을 회수하였다. investigation can be separated into sa

• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.89-94
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• 2021

The mechanical reliability of flexible devices has become a major concern on their commercialization, where the importance of reliable bonding is highlighted. In terms of component materials' properties, it is important to consider thermal damage of polymer substrates that occupy large area of the flexible device. Therefore, room temperature bonding process is highly advantageous for implementing flexible device assemblies with mechanical reliability. Conventional epoxy resins for the bonding still require curing at high temperatures. Even after the curing procedure, the bonding joint loses flexibility and exhibits poor fatigue durability. To solve this problems, low-temperature and adhesive-free bonding are required. In this work, we develop a room temperature bonding process for polymer substrates using carbon nanotube heated by microwave irradiations. After depositing multiple-wall carbon nanotubes (MWNTs) on PET polymer substrates, they are heated locally with by microwave while the entire bonding specimen maintains room temperature and the heating induces mechanical entanglement of CNT-PET. The room temperature bonding was conducted for a PET/CNT/PET specimen at 600 watt of microwave power for 10 seconds. Thickness of the CNT bonding joint was very thin that it obtains flexibility as well. In order to evaluate the mechanical reliability of the joint specimen, we performed lap shear test, three-point bending test, and dynamic bending test, and confirmed excellent joint strength, flexibility, and bending durability from each test.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.4
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• pp.536-547
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• 1997

For various angular velocities of crucible and crystal, the characteristics of melt flows, temperatures and concentrations of oxygen are numerically studied in the Czochralski furnace with a uniform axial magnetic field. Buoyancy effect due to the heating of crucible wall and thermocapillary effect due to the temperature gradient at the free surface, can be differentiably suppressed by the centrifugal forces due to the rotations of the crucible and crystal. The most important factor which yields the centrifugal forces is the rotation velocity of the crucible, that influences the fields of velocities, temperatures and concentrations. In the case that the crucible rotation velocity is not high, the rotations of the crystal gives rise to the centrifugal forces effectively.

• Applied Biological Chemistry
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• v.37 no.6
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• pp.456-462
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• 1994

Lysozyme-dextran hybrids were prepared by incubated storage at $60^{\circ}C$ and 80% relative humidity for 16 days. The emulsifying properties of the hybrids were about 14 times higher than those of native lysozyme and were about 3 times higher than those of commercial emulsifiers. Lytic activity of the hybrids remained about 83% that of native lysozyme when mesured against Micrococcus lysodeikticus as a substrate. The excellent emulsifying properties of the hybrids were maintained even at pH 3 and were further improved at pH 10. The emulsifying properties of the hybrids were greatly improved by preheating the hybrids at $100^{\circ}C$. In addition the lysozyme-dextran hybrids showed an antimicrobial effect on Gram-negative bacteria.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.1
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• pp.9-16
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• 2005

Jet vane is an useful component which is installed at the end of a nozzle for the purpose of the posture control and the secure controlling stability during the initial launching of a rocket. During several seconds from its initial launching moment, the JV driving part is heated due to the direct contact of the vane with the combusted gas and the vane is ablated mechanically or chemically. In this study, as the fundamental study for the thermal analysis of jet vane, the heat transfer into a jet vane which is located in the uniform supersonic flow field is calculated. For this, boundary layer integral method and finite difference method are used simultaneously. Based on the thermal boundary conditions derived from the analysis, the transient heat conduction in the vane is also calculated.

• Fire Science and Engineering
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• v.19 no.4 s.60
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• pp.18-25
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• 2005

In this study, numerical analysis of two-dimensional unsteady natural convection of air in a square enclosure heated from below, was performed as a basic research of fire science. SIMPLE algorithm was used to the pressure term of momentum equations in the numerical analysis. The numerical analysis were studied for the two model cases and two heat conditions, respectively, which are different with insulation of enclosures and position of heat applied. Also, the ceiling temperatures of enclosure were measured to compare the accuracy of numerical analysis, and it is found that the temperature predicted by numerical analysis were agreed well with the measurements. Streamline and isotherm of the each model case were acquired for each time step.

• Food Science and Preservation
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• v.30 no.6
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• pp.1043-1055
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• 2023

This study was conducted to suggest an extraction method for preparing the extract from green tea leaves that possess enhanced antioxidant and antibacterial activities. Different ethanol concentrations were tested to recover phenolics and flavonoids, and 50% ethanol was the best under heat treatment (121℃, 15 min). The ethanol extract exhibited excellent DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity and growth inhibition against B. cereus, B. licheniformis, S. aureus subsp. aureus, and A. hydrophila subsp. hydrophila. To enhance the antioxidant and antibacterial activities, cell-wall degrading enzymes (2.5% cellulose+2.5% pectinase, v/w dry sample) treatment and Saccharomyces cerevisiae fermentation were applied singly or in combination. The enzymatic treatment of green tea leaves notably increased extraction yield. However, the antioxidant and antibacterial activities of the extract were lower than those of the control (heat-treated 50% ethanol extract). In contrast, the yeast fermentation alone did not affect the yield, but enhanced antioxidant and antibacterial activities, contributing to the increase in the extract's total phenolic and flavonoid contents.

• Korean Journal of Microbiology
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• v.49 no.3
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• pp.253-261
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• 2013

The purpose of this study was to investigate the aflatoxin $B_1$ binding of lactic acid bacteria (LAB) isolated from Korean traditional soybean paste and to evaluate the effect of incubation conditions and physico-chemical factors on the binding ability of LAB to this mutagen. The amount of aflatoxin $B_1$ bound by Enterococcus faecium DJ22, Lactobacillus fermentum DJ35, Lactobacillus rhamnosus DJ42, and Lactobacillus pentosus DJ47 was strain specific with the percent bound ranging from 19.3% to 52.1%. However, Enterococcus faecalis DJ14, Lactobacillus panis DJ29, and Pediococcus halophilus DJ50 strains did not exhibit any of the binding ability to aflatoxin $B_1$. For most strains, the binding ability was significantly affected by the environmental conditions such as the aflatoxin $B_1$ level, incubation time and temperature, and the initial cell count of LAB. The stability of the aflatoxin $B_1$-bacteria complexes was significantly more unstable after washing. In addition, the binding stability between viable and nonviable cells was not statistically significant. Treatment with heating, acidic pH, ${\alpha}$-amylase, protease, lysozyme, or sodium metaperiodate caused a significant (P<0.05) decrease in aflatoxin $B_1$ binding for the tested strains, suggesting that carbohydrates or proteins in the cell walls may be involved in aflatoxin $B_1$ binding ability. Since the aflatoxin $B_1$ binding of LAB was significantly reduced (P<0.05) by the pretreatment of the urea, the binding force observed in this study may have resulted from hydrophobic interaction.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.1
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• pp.27-32
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• 1994

For the improvement of seasoned kelp products, their processing conditions were examined. To find the optimal processing conditions for seasoned kelp, kelp was prepared by cooking for 0.5, 1.0, 2.0, 3.0 and 4.0 hrs at $80^{\circ}C$ in seasoning solution which contained $20\%$ sugar, $11\%$ sorbitol, $3.5\%$ NaCl and $1.6\%$ MSG. The penetration of seasonings into kelp increased with cooking time. Improved texture and seasoning penetration was achieved by using $3\%$ acetic acid in the seasoning solution. The seasoning component contents of the kelp seasoned varied within the following ranges: sugar $0.150{\sim}0.182\%$, sorbitol $0.085{\sim}0.127\%$, acetic acid $0.015{\sim}0.019\%$, MSG $0.21{\sim}0.37\%$, NaCl $0.30{\sim}0.40\%$, fructose $0.009{\sim}0.024\%$ and glucose $0.003{\sim}0.031\%$, respectively. Fructose and glucose were measured in seasoned kelp treated with acetic acid. Water activity of seasoned kelp varied from 0.36 to 0.48 according to seasoning composition.