• Food Science and Preservation
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• v.9 no.2
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• pp.212-220
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• 2002

Spray drying was used a means for microencapsulation of Aster scaber and Aster glehni. The optimum conditions of spray drying were found to be 210$^{\circ}C$ for the inlet temperature and 5 $m\ell$/min for the feeding rate. The color difference decreased by 12∼25 % far the herb extracts depending on storage temperatures. With an increase in storage temperature, color of the control changed considerably compared to microencapsulated powders. This is due to the fact that wall materials minimized effect of oxygen on the herb extracts. Microencapsulated powders in the amounts of 50 ppm and 250 ppm added to hydrogenated soybean oils led to lower acid values and conjugated diene values during 6 day storage. Compared to the control, the herb extracts displayed 16∼48% increase in antioxidation effect, while the microencapsulated powders exhibited 46∼88% increase. Extracts also showed lower conjugated dienoic acid contents than those of the control. Although antioxidation effect of the microencapsulated powders did not prevail on the significant level in the early stage of storage of oils tested, it became predominant after one week of storage as wall materials were gradually degraded under the high temperature thereby releasing core material from the microcapsule.

• Geophysics and Geophysical Exploration
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• v.9 no.4
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• pp.304-315
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• 2006

We have examined the applicability of f-k analysis to the GPR direct wave measurement for water content to characterize vadose zone condition. When the vadose zone consists of a dry surface layer over wet substratum, we obtained f-k spectra where most of the energy is bounded by the air and dry soil velocities. In this case, dry soil velocity was successfully estimated by using high frequency data. On the other hands, when wet soil overlies dry substratum, the f-k spectra show a contrasting response where most of the energy travels with the velocity bounded by dry and wet soil velocities. In this case, the radar waves are trapped and guided within wet soil layer, exhibiting velocity dispersion. By adopting modal propagation theory, we could formulae a simple inversion code to find two layer's dielectric constants as well as layer thickness. By inverting the velocity dispersion curve obtained from f-k spectra of synthetic modeling data, we could obtain good estimates of dielectric constants of each layer as well as first layer thickness. Moreover, we could obtain more accurate results by including the higher mode data. We expect this method will be useful to get the quantitative property of real subsurface when the field condition is similar.

• Journal of the Korean Electrochemical Society
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• v.19 no.2
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• pp.50-56
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• 2016

Spherical lithium manganese oxide spinel, $Li_{1.10}Mn_{1.86}Al_{0.02}Mg_{0.02}O_4$ was prepared by wet-milling, spray-drying, and sintering process. In the spray-drying process, solid content in slurry was varied from 20 to 30 wt%. In the sintering process, the precursors have been sintered under air or $O_2$ atmosphere. While the as-prepared samples exhibit excellent electrochemical properties at room temperature, the discharge voltage profiles at 5.0C are very different one from another. The origin for the difference especially at initial state of discharge is oxygen defect. The sample prepared in air has larger capacity related to the plateau at 3.3 V (vs. $Li/Li^+$) which is caused by the oxygen defects than the one prepared in $O_2$. The difference of discharge voltage profiles especially at the final state of discharge comes from different diffusion rate of $Li^+$ ions. The sample prepared from 30 wt% solid content of slurry shows twice higher diffusion rate than the samples prepared from 20 wt% solid content, which is attributed to better compactness between primary particles for the sample prepared from 30wt % solid content than the one prepared by 20 wt%.

• Korean Journal of Food Science and Technology
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• v.15 no.2
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• pp.150-154
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• 1983

Mushroom, Lentinus edodes which had been dried at $50^{\circ}C$ for 20 hours were extracted with small amount of ethanol, methanol, chloroform and petroleum ether, respectively. The extracts were then dissolved in edible soybean oil, and the resulting substrates and a portion of the soybean oil (control) were placed in an incubator $(37.0{\pm}1.0^{\circ}C)$ for eight weeks. Peroxide values and TBA values of control and the substrates were determined regularly during the storage period. The results of the present study were as follows: 1. The moisture contents of the mushroom which was 84.88% on wet basis at the time of harvest were reduced to 15.12% after drying. 2. Extracts obtained from alcohols were effective in retarding the POV development. 3. There was not much difference among the TBA values after 14 days, but significant difference of the TBA values in control and the substrates extracts were observed in longer storage period TBA values of substrate containing ethanol and methanol in the later stage period were smaller than that of the substrates containing petroleum ether and chloroform. 4. In view of the POV and TBA value development, ethanol and methanol were more effective solvents for the extraction of antioxidant compounds in the dried mushroom than chloroform and petroleum ether.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.3
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• pp.181-189
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• 1983

A study on the qualify changes of fish meat during drying and storage has been carried out with filefish meat. Filefish meat was dried in a forced air dryer at 40 and $55\%$ for 20 hours with an air velocity of 0.4 m/sec under different conditions of relative air humidities in the range of 10 to $50\%$. The dried fish meat was stored at $30^{\circ}C$ in chambers with constant relative humidities controlled by the use of conditioned air stream passing through the saturated salt solutions. The qualify of filefish meat was evaluated with the brown color densities developed by lipid oxidation and Maillard reaction. Changes of viable cell count during drying and storage were also discussed. The predominant reaction for the brown color developed during the study period was the lipid oxidation. The lipid oxidation rate during drying at constant temperature was appreciably affected by water activities at the drying surfaces of filefish meat during the falling drying rate period. The lipid oxidation rate was the slowest under the condition of the relative air humidity of around $30\%$. In samples stored at water activity of 0.33, the lipid oxidation rate was retarded remarkably in comparison with the samples with lower or higher water activities. The addition of $1\%$ table salt, $1.5\%$ D-sorbitol and $6\%$ sucrose slightly lowered the water activity with the slowest lipid oxidation rate. Such additives resulted the increase of the water soluble brown color densities, which seemed due to the increase of mobility of the water soluble substances by the result of the increase of equilibrium water content. Microflora of the samples immediately after drying consisted of ca. $30\%$ of coccus types, ca. $65\%$ of rod types and ca. $5\%$ of molds and yeasts. During the storage of the samples with a water activity of 0.76, the ratio of the coccus types to the total microflora was increased remarkably while that of the Gram negative non-spore rod types was decreased. The ratios of the Gram positive rod types, molds and yeasts during the storage were nearly constant.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.123.1-123.1
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• 2010

수평형 지중열교환기의 최적설계를 위해서는 되메움재의 광물특성 및 입자크기, 열전도도(thermal conductivity), 열용량(heat capacity)등과 같은 열적 특성을 파악 하는 것은 중요하다. 수평형 지중 열교환기용 되메움재의 열전도도를 파악하기 위해 비정상 열선법을 적용한 QTM-500을 사용하여 포화도에 따른 천연규사-물-공기 혼합물의 열전도도를 측정하였다. 측정된 열전도도를 개별요소법(Discrete Element Mothod)에 근거한 2차원 수치해석 프로그램인 PFC2D(Particle Flow Code in 2 Dimension)를 이용하여 비교 분석하였다. 수치해석에서는 혼합물의 건조밀도를 일정하게 유지한 상태에서 포화도에 따라 가상의 물 입자 개수를 변화시켰다. 개별요소법을 이용한 열전달 수치해석에서는 입자의 접촉을 통해 발생한 thermal pipe에 의해 열전달이 이루어진다. 이러한 thermal pipe의 열전도도는 접촉된 두 입자의 열전도도와 접촉면의 평균 열전도도를 고려하여 적용하였다.

• Applied Microscopy
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• v.33 no.3
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• pp.215-222
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• 2003

The ultrastructure of damaged hair shaft from blow-drying at typical temperature $40{\sim}170^{\circ}C$ for daily beautiful face have been investigated by using transmission electron microscope and scanning electron microscope. When we used to hair dryer for a long time in our everyday life, the following morphological alternations were found in hair. First, the partial of scales in outer cuticle were detached simultaneously with separation of intercellular membrane complex of cuticle cells. Then hair broke cuticle off and exposed to cortex. Secondly, the cortical cell in the cortex was fissured into its macrofibril. The melanin granules were scattered between macrofibrils. As a result, I confirmed that blow-drying removed the hair's bonded water and made hard on hair which lost elasticity. After all, hair showed irregular, rough surface and vanished its luster.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.235-244
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• 2001

Liquefaction may be caused by sudden decrease in the soil strength under undrained conditions. This loss of soil strength is related to the development of excess pore pressures. During this study, fines content affects the maximum and minimum void ratios are investigated. The results of static and cyclic triaxial test on silty saturated sands are presented. These tests are performed to evaluate liquefaction strength and static and cyclic behavior characteristics. The samples are obtained from Saemangeum and drying on air. The main results are summarized as follows : 1) The maximum and minimum void ratio lines follow similar trends. 2) Maximum and minimum void ratios are established at 20~30% fines content. 3) As confining pressures and overconsolidation ratio are increased, the resistance to liquefaction are increased. 4) Instability friction angles are increased with increasing initial relative density. 5) The resistance to liquefaction are decreased with increasing effective stress ratio.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.10
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• pp.804-808
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• 2010

In this paper, we studied the dielectric breakdown voltage characteristics by the AC withstand voltage test on using green insulation dry air instead of $SF_6$ insulation gas used in the GIB (gas insulated bus) of 362 kV GIS (gas insulated switchgear). The AC withstand voltage test applied to the standard KEPCO's 362 kV GIB with dry air insulation, and the equivalence of dielectric breakdown voltage for dry air and $SF_6$ gas were examined, and the empirical formulas of dielectric breakdown voltage for dry air were calculated, and the criterion of AC withstand voltage test for dry air insulation was derived. Using the criterion, dry air can be used instead of $SF_6$ gas for 362 kV GIB in the factory acceptance test was confirmed.

• 월간 기계설비
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• s.267
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• pp.65-71
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• 2012

지난 8월 13일 서울 종로구 소격동 국립현대미술관 서울관 공사현장에서 화재 발생으로 4명이 숨지고 18명이 중경상을 입는 등 많은 인명피해를 냈다. 이처럼 인명피해가 컸던 것은 우레탄 공사를 하던 밀폐공간에서 불이 나면서 발생한 유독가스 때문에 사람들이 제대로 대피하지 못했기 때문이다. 사고발생 원인으로 '용접공사' 여부를 놓고 공방을 벌였으나 경찰은 '전기합선'이라는 잠정 결론을 내렸다. 지난 2008년 1월에 발생한 경기도 이천 냉동창고 화재는 40명의 목숨을 앗아갔다. 화재 원인은 냉동배관을 설치하면서 전기 용접을 하기 위해 불을 붙였다가 공기 중에 차 있던 유증기(기름증기)와 만나면서 폭발이 일어난 것이었다. 인화성 액체(유기용제)를 취급하는 건설현장에서는 다량의 유증기가 발생할 수 있을 뿐만 아니라 건조한 조건일 경우 정전기에 의한 화재 폭발 누출사고의 발생 위험이 높다. 기계설비공사에서 화재, 폭발 위험성이 가장 큰 공사는 용접공사이기에 용접공사를 할 때 화재, 감전의 위험성을 배제한 후 공사에 들어간다. 용접으로 인한 사망사고의 유형으로는 용접 중 추락사고와 더불어 용접 불꽃이 가연성 물질에 옮겨 붙어 화재 발생으로 인한 질식사, 용접작업 중 절연체가 파손된 용접기 홀더 충전부의 접촉으로 인한 감전사 등이 있다. 본지는 용접으로 인한 화재 감전 등의 사고발생을 미연에 방지하기 위해 안전작업 수칙 및 안전수칙 체크리스트, 재해사례를 지난호부터 시리즈로 연재하고 있다.