• 대한본초학회지
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• 제37권4호
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• pp.17-29
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• 2022

Objective : The present study comparatively analyzed the anti-obesity effect of Arctium lappa L. roots with and without microwave processing. Methods : Four HFD groups except for the Normal group (n=8) were allocated: Control, microwave-processed dried Arctium lappa L. roots (MAL) extract 400 mg/kg/d (MAL400), MAL extract 800 mg/kg/d (MAL800), and the dried Arctium lappa L. roots (DAL) extract 800 mg/kg/d (DAL800). The efficacy of MAL and DAL was confirmed in terms of the serum biochemical index, protein expressions related to the synthesis of triglyceride (TG) and total cholesterol (TC) and 𝛽-oxidation, and histopathological staining. Results : Both MAL and DAL treatments significantly reduced final body weight and body weight gain. MAL800 treatment significantly reduced serum TG, TC, low-density lipoprotein cholesterol, and leptin levels, but the serum high-density lipoprotein cholesterol and adiponectin concentrations were dramatically increased. In particular, leptin in the MAL800 group was reduced by 14.1% compared with the DAL800 group. Moreover, the MAL800 treatment showed an effect superior to the DAL800 treatment in the reduction of serum TC, the sirtuin 1 (Sirt1) activation, and the inhibition of 3-hydroxy-3-methyl glutaryl coenzyme A reductase (HMGCR) gene expression. In particular, unlike the DAL800 treatment, MAL treatment significantly led to the activation of peroxisome proliferator-activated receptor alpha (PPAR𝛼). Subsequently, PPAR𝛼 meaningfully regulated downstream proteins associated with 𝛽-oxidation. Conclusion : These findings suggest that Arctium lappa L. roots with microwave processing effectively ameliorate obesity through the regulation of leptin and TC and the promotion of 𝛽-oxidation compared with Arctium lappa L. roots without microwave processing.

• 한국건축시공학회지
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• 제12권5호
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• pp.503-509
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• 2012

In this study, the potential use of indigenous natural loess(Hwangtoh) as a new construction material, via alkali activation in conjunction with microwave heating, was investigated. Hwangtoh pastes with three different mix proportions of varying alkali liquid concentrations at a constant liquid-to-Hwangtoh ratio of 0.55 were prepared. Through the investigation it was found that it is possible to prepare Hwangtoh paste with $19.02N/mm^2$ at the age of 4 hours with the alkali solution of 8M NaOH and 1:4.5 mass ratio of liquefied $Na_2SiO_3$ at the curing temperature of $60^{\circ}C$ by microwave heating. The strength development at early age of the alkali activated Hwangtoh paste specimens may be attributed to both a higher rate of reaction and moisture evaporation due to microwave heating.

• Journal of Biosystems Engineering
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• 제37권6호
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• pp.385-397
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• 2012

Purpose: Drying characteristics of sawdust was studied under batch mode using lab scale microwave dryer. The objective of this study was to investigate the effect of material load and microwave output power on drying characteristics of sawdust. Methods: Material load and microwave output power were varied from 23 to 186 g and 530 to 370 W respectively. Different kinetic models were tested to fit the drying rates of sawdust. Similarly, the activation energy was calculated by employing the Arrhenius equation. Results: The drying efficiency increased considerably, whereas the specific energy consumption significantly decreased with increase in material load and microwave output power. The cumulative energy efficiency increased by 9%, and the specific energy consumption decreased by 8% when the material load was increased from 23 to 186 g. The effective diffusivity increased with decrease in material load and increase in microwave output power. The previously published model gave the best fit for data points with $R^2$ and RMSE values of 0.999 and 0.01, respectively. Conclusions: The data obtained from this study could be used as a basis for modeling of large scale industrial microwave dryers for the pellet production.

• Carbon letters
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• 제24권
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• pp.62-72
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• 2017

The aim of this work was to evaluate the dielectric properties of impregnated and activated palm kernel shells (PKSs) samples using two activating agents, potassium carbonate ($K_2CO_3$) and sodium hydroxide (NaOH), at three impregnation ratios. The materials were characterized by moisture content, carbon content, ash content, thermal profile and functional groups. The dielectric properties were examined using an open-ended coaxial probe method at various microwave frequencies (1-6 GHz) and temperatures (25, 35, and $45^{\circ}C$). The results show that the dielectric properties varied with frequency, temperature, moisture content, carbon content and mass ratio of the ionic solids. PKSK1.75 (PKS impregnated with $K_2CO_3$ at a mass ratio of 1.75) and PKSN1.5 (PKS impregnated with NaOH at a mass ratio of 1.5) exhibited a high loss tangent ($tan{\delta}$) indicating the effectiveness of these materials to be heated by microwaves. $K_2CO_3$ and NaOH can act as a microwave absorber to enhance the efficiency of microwave heating for low loss PKSs. Materials with a high moisture content exhibit a high loss tangent but low penetration depth. The interplay of multiple operating frequencies is suggested to promote better microwave heating by considering the changes in the materials characteristics.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 추계 학술논문 발표대회
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• pp.25-26
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• 2011

The objective of this study is to develop the prototype system for microwave heating in a manufacture process of alkali activated Hwangtoh binder as replacement materials for the cement in concrete. In order to achieve this, four research phases are carried out as follows: 1) establishment of a system concept 2) deduction of a system element 3) design of the entire system 4) making of the prototype system for microwave heating.

• 한국식품영양과학회지
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• 제29권1호
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• pp.168-173
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• 2000

The purpose of this study was to investigate the changes of microsomal mixed function oxidase (MFO) and xanthine oxidase activities (XOD) in the liver of rats exposed to microwave. Sprague-Dawley male rats weighing 200$\pm$10g body weight were randomly assigned to a normal and microwave exposed(MW) groups; microwave exposed groups were divided into two groups; microwave (MW) group and green tea(GT) gropu which were fed distilled water and green tea extracts during experimental periods, respectively. Rats were irradiated with microwave at the frequency of 2.45 GHz for 15min and rats wre sacrificed at the 4th day of the microwave irradiaton. The hemoglobin level of GT group was higher than that of the normal gropu and MW group, but the hematocrit value was not significantly different among all experimental gropus. The activity of serum GOT of MW group was significantly increased but that of GT group was similar to normal group. Activities of GPT were not significantly different among all experimental groups. Liver XOD activity was significantly increased in the microwave exposed groups but green tea normalized the XOD activity. The activity of hepatic microsomal cytochrome P450 was significantly increased in MW group compared to normal group and that of GT group was similar to that of the normal group. The activity of hepatic microsomal NADPH-cytochrome P450 reductase was also significantly increased in MW group compared to normal group, but that of GT group was similar to that fo the normal group. In conclusion, the activities of MFO and XOD were elevated by microwave irradiaton, but the activation of MFO system as well as the damage of the liver by microwave were reduced by green tea supplementation.

• 한국표면공학회지
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• 제44권4호
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• pp.131-136
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• 2011

A kinetic study has been made for the growth of nanocrystalline diamond (NCD) particles to a continuous thin film on silicon substrate in a microwave plasma chemical vapor deposition reactor. Parameters of deposition have been microwave power of 1.2 kW, the chamber pressure of 110 Torr, and the Ar/$CH_4$ ratio of 200/2 sccm. The deposition has been carried out at temperatures in the range of $400\sim700^{\circ}C$ for the times of 0.5~16 h. It has been revealed that a continuous diamond film evolves from the growth and coalescence of diamond crystallites (or particles), which have been heterogeneously nucleated at the previously scratched sites. The diamond particles grow following an $h^2$ = k't relationship, where h is the height of particles, k' is the particle growth rate constant, and t is the deposition time. The k' values at the different deposition temperatures satisfy an Arrhenius equation with the apparent activation energy of 4.37 kcal/mol or 0.19 eV/ atom. The rate limiting step should be the diffusion of carbon species over the Si substrate surface. The growth of diamond film thickness (H) shows an H = kt relationship with deposition time, t. The film growth rate constant, k, values at the different deposition temperatures show another Arrhenius-type expression with the apparent activation energy of 3.89 kcal/mol or 0.17 eV/atom. In this case, the rate limiting step might be the incorporation reaction of carbon species from the plasma on the film surface.

• 한국재료학회지
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• 제17권12호
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• pp.669-675
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• 2007

Hydroxyapatite (HAp) and biphasic calcium phosphate (BCP) nano powders were synthesized using the microwave-assisted synthesis process dependent on pH and microwave irradiation time. The average size of a powder was less than 100 nm in diameter. Through in-vitro cytotoxicity tests by an extract dilution method, the HAp and BCP nano powders have shown to be cytocompatible for L-929 fibroblast cells, osteoblastlike MG-63 cells and osteoclast-like Raw 264.7 cells. The activation of osteoblast was estimated by alkaline phosphatase (ALP) activity. When the HAp and BCP were treated to MG-63 cells, alkaline phosphatase activities increased on day 3, compared with those of the untreated cells. Also, the collagen fibers increased when the HAp and BCP powders suspension were treated to MG-63 cells, compared to those of the untreated cells. Quantitative alizarin red S mineralization assays showed a trend toward increasing mineralization in osteoblast cultured with powder suspension. In conclusion, hydroxyapatite and biphasic calcium phosphate appeared to be a bone graft substitute material with optimal biocompatibility and could be further applied to clinical use as an artificial bone graft substitute.

• Bulletin of the Korean Chemical Society
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• 제27권2호
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• pp.286-290
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• 2006

Rapid and facile syntheses of N-alkenyl lactam series via condensation between lactams and a variety of aldehydes such as n-propanal, isobutanal, n-butanal, n-hexanal, n-octanal and phenylacetaldehyde were studied under microwave or conventional heating. Various solid catalysts and solvents were examined to maximize the yields of condensation reactions.

• 보존과학회지
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• 제26권1호
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• pp.77-83
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• 2010

국내에 서식하는 지중흰개미는 목재 내부에 공동화 현상이 발생되어 붕괴가 일어나기 직전까지도 외관상 특별한 변화가 발견되지 않는다. 이러한 흰개미의 활성을 비파괴적으로 측정하는 기술은 현재 국내에 적용된 사례가 없었다. 따라서 본 연구는 극초단파 탐지 장비(Termatrac, Australia)를 이용하여 목조 문화재의 비파괴 진단 기술을 정립하고자 한다. 연구 결과, 소나무의 경우 16cm(민감도 5, 6), 느티나무와 Douglas fir의 경우 17cm(민감도 5, 6)까지 측정이 가능하여 국내 대부분의 목조 건축물에 적용이 가능할 것으로 판단되었다. 현장조사 결과 전국 목조건축물 231동 중 33.8%가 흰개미에 의한 손상을 입었으며, 7.8%인 총 18개 건물에서 흰개미 가해가 진행 중인 것을 확인할 수 있었다. 이와 같은 결과를 통해 목조 문화재의 비파괴 분석법으로서 적용이 가능할 것이라 예상된다.