• Food Science and Biotechnology
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• 제16권5호
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• pp.771-777
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• 2007

Sliced and whole root of rehmannia were dehydrated in a laboratory dryer at 40, 60, 80, and $100^{\circ}C$ to evaluate the kinetic parameters for dehydration of rehmannia. The drying curves of both samples were characterized by a falling-rate drying period only. Sliced rehmannia dried 1.1 to 3.1 times faster than whole root of rehmannia depending on drying temperature. Equilibrium moisture content (EMC) of rehmannia samples at the drying temperature tested were 0.069-0.078 g water/g dry solid, which was coincided with the monolayer moisture content (0.06 and 0.07 g water/g dry solid) evaluated from desorption isotherms using GAB (Guggenheim-Anderson-de Boer) model. A logarithmic model for thin layer drying was applied to evaluate the drying time to reach EMC ($t_{EMC}$) and drying constant (k). The effect of temperature on $1/t_{EMC}$ and k was described by the Arrhenius model with activation energy values of 32.56 and 47.14 kJ/mol determined using the former parameter, and 34.27 and 38.26 kJ/mol determined using the latter parameter for sliced and whole root of rehmannia, respectively.

• Journal of Biosystems Engineering
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• 제21권1호
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• pp.60-71
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• 1996

The purposes of this study were to develop a simulation model and to determine minimum specific airflow rate requirements for natural air drying of rough rice in Korea. A simulation model was developed considering energy and mass balances within grain bed, drying and rewetting rates, and hysterisis effect between sorption and desorption isotherms. As the results of validation test, the moisture contents predicted by the model agreed very well with the actual data. The criteria for determining minimum specific airflow rate requirements was that the top loom layer in the bin be dried to a moisture content below 16 percent wet basis with less than 0.5% drymatter decomposition. The minimum specific airflow rate requirements in 13 locations of Korea were presented based on the worst one among the past 7 to 13-year weather data. These requirements were also presented for all the combinations of three harvest dates and four harvest moisture contents. Specific airflow rate requirements seemed to be half by each 2 percent reduction in moisture content from 24 percent. As harvest date was delayed by 10 days from October 1, these requirements were reduced by about 20 to 40 percent.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.896-905
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• 1993

Thin-layers of wheat and barley are dried at near-ambient temperatures(3.5$^{\circ}C$ -5$0^{\circ}C$) in order to obtain the intrinsic drying data. The well established apparatus was modified to enable it to record all the sample weight data in still air by using a purpose -built automatically controlled sliding valve. The air could be diverted in less than 0.5seconds and a 7 second period was required to attain a steady weight reading. With this apparatus, very smooth drying curves were obtained. The data of sample weight , drying temperature and dew point temperature wee recorded continuously . The drying process was terminated when the moisture content change in 24 hours was less than 0.004 d.b. This was achieved by drying a sample for about a week . The final points were recorded as the dynamic equilibrium moisture content(EMC). The drying data were than fitted to the exponential Newton model and the dynamic EMC data were fitted to the Modified-Chung-Pfost Model . All the fitted parameters are given and comparison is made with previous published data. The comparisons who that the current drying constants are lower than the previous data, the dynamic EMC data obtained for wheat and barely agree with the previous data. The results show that to obtain the drying constant in the exponential Newton model, adequate drying time is necessary.

• Natural Product Sciences
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• 제10권1호
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• pp.16-19
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• 2004

Triphala churna is a widely used herbal formulation that contains equal proportion of dried fruit powder of Emblica officinalis, Terminalia chebula and Terminalia belirica. In the Indian system of medicine, it is used in cleaning wounds, urinary disorders, diabetes mellitus, leprosy, constipation, eyesight promotion, piles, and as a rejuvenator. In the present study, the methanolic extract of 5 commercial Triphala was evaluated for antioxidant activity by 1,1-diphenyl-2-picryl-hydrazyl free radical scavenging method, total phenolic content by Folin-Ciocalteu method and gallic acid equivalents (GAE) by high performance thin layer chromatographic (HPTLC) method. All extracts exhibited antioxidant activity significantly. The $IC_{50}$ of the extracts ranged between $7.16\;to\;12.96\;{\mu}g/ml$. The total phenolic content of the extracts was found to be 195.3-296.4 mg of GAE/gm of GAE/gm dw. The HPTLC chromatographic data reveal that the content of GAE present in the extract was found to be $7.17-4.11\;{\mu}g/ml$. The study reveals that out of the churnas analysed, C was found to exhibit the most potent antioxidant activity. A clear correlation between $IC_{50}$ and content of GAE nor the total phenolic content could be observed. The study reveals that the consumption of Triphala would exert several beneficial effects by virtue of its antioxidant activity.

• Journal of Ginseng Research
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• 제22권3호
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• pp.155-160
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• 1998

This stuffy was carried to establish a new efficient method for the preparation of edible crude ginseng saponin. The conventional butanol extraction and resin adsorption methods were compared for the contents of total crude ginseng saponin and major ginsenosides. Seventy- percent methanol extract was applied to Diaion HP-20 column and the resin was washed with Hn and eluted with absolute methanol. The methanol elute was dried in vivo and analyzed for its ginsenosides. Use of ethanol instead of methanol to make edible crude ginseng saponin gave a similar result. Butanol extraction was performed by the conventional method. The final aqueous layer from butanol extraction was passed through Diaion HP-20 column followed by elution with methanol and Diaion HP-20 passed fraction was extracted with butanol to recover remaining components, respectively, in order to determine saponin loss. TLC and HPLC qualitatively and quantitatively monitored Ginsenosides, respectively. Loss of ginsenosides was higher in butanol extraction method than in Diction HP-20 adsorption method. In addition, saponin fractions prepared by Diction HP-20 adsorption method showed higher content of each ginsenoside, showing 8.2% higher purity than that of butanol extracted fraction. From these results, we propose the resin adsorption method as a new efficient measure for the preparation of crude ginseng saponin, which is edible by using spirit instead of methanol.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.148-148
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• 2017

Surface modification is a type of mechanical manipulation skills to achieve extensive aims including corrosion control, exterior appearance, abrasion resistance, electrical insulation and electrical conductivity of substrate materials by generating a protective surface using electrical, physical and chemical treatment on the surface of parts made from metallic materials. Such surface modification includes plating, anodizing, chemical conversion treatment, painting, lining, coating and surface hardening; this study conducted cavitation experiment to assess improvement of durability using anodizing. In order to observe surface characteristics with applied current density, the electrolyte temperature, concentration was maintained at constant condition. To prevent hindrance of stable growth of oxide layer due to local temperature increase during the experiment, stirring was maintained at constant speed. In addition, using galvanostatic method, it was maintained at processing time of 40minutes for 10 to $30mA/cm^2$. The cavitation experiment was carried out with an ultra sonic vibratory apparatus using piezo-electric effect with modified ASTM-G32. The peak-to-peak amplitude was $30{\mu}m$ and the distance between the horn tip and specimen was 1mm. The specimen after the experiment was cleaned in an ultrasonic bath, dried in a vacuum oven for more than 24 hours, and weighed with an electric balance. The surface damage morphology was observed with 3D analysis microscope. As a result of the study, differences were observed surface hardness and anti-cavitation characteristics depending on the development of oxide film with the anodizing process time.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.492-495
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• 1987

In this study, PLZT ceramics were fabricated by freeze-drying and normal sintering method. The compositional rate of specimen was selected 9/65/35 (La/Zr/Ti) which have good optical and dielectric properties, sintering time was varied 1, 10, 30, 40, 50, 55, 60 and 65 hr at $1250^{\circ}C$. After sintering, the optical and dielectric properties were investigated with the grain size. As the result of the experiment, freeze-dried powder appeared particle size less than 1 um. The relative dielectric constant was increased linearly with the sintering time, specimen which sintered for 65 hr had the highest value, 5780. Grain was grown with increasing time, in the case of specimen sintered for 60 hr, the grain size was 8.4 um. Transmittance was increased with the grain size. In the case of 8.4 um grain size, the transmittance was 56 %. Curie temperature was decreased linearly by the surface-layer effect of space-charge, in the case of grain size which were 1.8 um and 8.4 um, appeared at $100^{\circ}C$ and $80^{\circ}C$, respectively.

• 한국균학회지
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• 제20권4호
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• pp.302-308
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• 1992

Seven genera and 15 species of fungi were isolated from 50 samples of then different steps of dried onion (5 samples of each step) collected from an onion factory in Sohag Governorate, Egypt, and grown on glucose-Czapek's agar (7 genera and 15 species) and 10% NaCl glucose-Czapek's (2 genera and 6 species). The average total counts of fungi were gradually decreased throughout the different steps of drying from 2090 to zero and 152 to zero colonies/g on glucose-Czapek's agar and 10% NaCl glucose-Czapek's agar media, respectively. Aspergillus was the most common genus on the two types of media used. The dominant species were Aspergillus niger, A. flavus, A. terreus, Penicillium chrysogenum and Fusarium of oxysporum on glucose-Czapek's agar and A. terreus and A. niger on 10% NaCl glucose-Czapek's agar. The chloroform extracts of different samples were tested for the presence of mycotoxins using thin layer chromatographic analysis. The results indicated that aflatoxin was present at concentrations decreased throughout the different steps of the drying from step No. 1, onion bulbs, $120\;{\mu}g/kg$; to step No. 8, standard A, $20\;{\mu}g/kg$ while step Nos. 9 & 10 (completely dry powdered onion) were free from aflatoxin. Citrinin was also present in the first three steps at concentrations gradually decreased from 30 to 10 mg/kg.

• 한국식품영양과학회지
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• 제32권1호
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• pp.22-28
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• 2003

단삼을 건조시켜 분쇄한 후 methanol로 추출하여 여러 용매로 분획하여 식품부패미생물의 증식억제 효과를 검색하고 그 항균성 물질을 분리하였다. 단삼의 chloroform 분획 추출물은 B subtilis, S. aureus, L. monocytogenes. E. coli 및 V, parahaemolyticus에 대해서 가장 낮은 농도인 250 $\mu\textrm{g}$/disc 농도에서 가장 높은 항균활성을 나타내었다. 단삼의 chloroform 추출물을 silica gel coliumn chromatography와 TLC로 monitoring 하여 항균성을 실험하였다. 이 결과 우수한 항균성 을 보인 sub fraction을 재차 분리하여 붉은색 결정의 항균성 물질을 얻었고 이를 GC/MS, $^1$H-NMR, $^{13}$C-NMR 로 구조분석 한 결과 화학식 이 $C_{19}$ H$_{20}$ O$_3$이며 분자량이 296.141 의 cryptotanshinone으로 동정되었다.

• 설비공학논문집
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• 제27권12호
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• pp.645-651
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• 2015

This paper presents an experimental study on the freeze drying process for poly ${\gamma}$ glutamic acid. The physical properties of poly ${\gamma}$ glutamic acid are measured during the freeze-drying process. The moisture contents of poly ${\gamma}$ glutamic acid according to the glass transient temperature are obtained by DSC (Differential Scanning Calorimetry) analysis. The end point of primary drying for the poly ${\gamma}$ glutamic acid with a thickness of 3 mm is obtained by measuring the thickness of the dried layer, the amount of moisture evaporation, the moisture content, and the pressure in the drying vacuum chamber during the freeze-drying process. By considering the variation in the glass transient temperature with respect to the moisture content of the material, a control schedule for the heating plate temperature is suggested during the secondary drying process.