• Journal of the Korean GEO-environmental Society
• /
• v.12 no.5
• /
• pp.5-12
• /
• 2011

Water content is one of the significant engineering properties of soil for predicting the behavior of soil matrix. Conventional drying oven can be widely used to obtain the values by drying the soil specimens for 16 to 24 hours at $105^{\circ}C$. Although a number of experimental data has been accumulated for the conventional method of drying soil for water contents, shortcomings of the method are still hard to overcome such as long drying time for in situ use and the difficulty of taking prompt actions against emergency cases. Recently, ASTM and JGS have established microwave oven drying techniques for obtaining water contents to cope with those problems. And the reliability evaluation study has been also performed on the microwave oven drying for water contents. Feasibility study of the microwave oven drying was performed to confirm the process of the technique with Jumunjin sand, kaolinite, bentonite, weathered granite soil, and organic soil. Investigation was also conducted on the factors affecting and enhancing the reliability of the technique.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.43 no.4
• /
• pp.570-576
• /
• 2014

Response surface methodology (RSM) was applied to optimize the microwave-assisted extraction (MAE) conditions for electron-donating ability, total phenol content, and total flavonoid content of Ligustrum lucidum Aiton. Ligustrum lucidum Aiton from different regions was tested, and Ligustrum lucidum Aiton from Haenam was chosen due to its higher total phenolic content, total flavonoid content, DPPH radical scavenging activity and ABTS radical scavenging activity compared to the other samples. Central composite design was used to optimize extraction of Ligustrum lucidum Aiton from Haenam as well as determine the effects of extraction temperature ($X_1$) and extraction time ($X_2$) on dependent variables ($Y_n$). Determination coefficients ($R^2$) of the regression equations for dependent variables ranged from 0.8858 to 0.9517. The optimum points were $131.68^{\circ}C$ for extraction temperature and 5.49 min for extraction time. Predicted values of the optimized conditions were acceptable when compared to experimental values.

• Korean Journal of Pharmacognosy
• /
• v.45 no.1
• /
• pp.55-61
• /
• 2014

Microwaves are non-ionizing electromagnetic waves of frequency between 300MHz to 300GHz and positioned between the X-ray and infrared rays in the electromagnetic spectrum. In recent years, the use of microwave for extraction of ingredient from plant material has shown remarkable research interest and potential. Scutellaria radix has been used as a traditional medicine for a variety of diseases. It has been reported to exert beneficial health effects, such as anti-bacterial, antiviral, anti-inflammatory, and free-radical scavenging. Oxidative stress or the accumulation of reactive oxygen species (ROS) leads neuronal cellular death and dysfunction, and it contributes to neuronal degenerative disease such as Alzheimer's disease, Parkinson's disease and stroke. In this study, we aimed to compare the neuroprotective and antioxidant effect of Scutellaria radix extracted by different methods using hot-water extraction (SBE-DW) or microwave extraction (SBE-DW-MW). As a result, we first examined HPLC analysis of hot-water and microwave extracts of Scutellaria radix. The hot-water and microwave extracts of Scutellaria radix showed the discernible difference patterns of HPLC analysis. Microwave-water extracts of Scutellaria radix increased DPPH radical scavenging activity more than hot-water extraction. Microwave-water extracts of Scutellaria radix also showed neuroprotective effects and ROS inhibition against glutamate-induced oxidative stress in mouse hippocampal HT22 cells, but hot-water extraction not showed. In addition, the phosphorylation of MAPKs induced by glutamate insult was prevented by microwave-water extracts of Scutellaria radix. Thus, these results suggested that microwave extraction can be utilized for improving the extraction efficiency and biological activity of Scutellaria radix.

• The Journal of Engineering Research
• /
• v.2 no.1
• /
• pp.113-123
• /
• 1997

The purpose of this paper is an optimum design of the shaped Cassegrainian antenna system for the base station. The process of the shaped Cassegrainian antenna design is as follows : 1) the aperture field distribution is determined so as to meet design specifications, 2) a proper design parameter is selected, 3) extracting of the dimension data for the main and sub-reflector antenna To do these, Hansen's distribution is chosen as the aperture field, and the far-field pattern from the aperture is predicted by the angular spectrum. Firstly, the aperture field distribution is designed to satisfy the specification for design frequency, it is confirmed if this distribution meet the specification for another frequency band. The main- and the sub-reflectors are synthesized so as for the given beamwaveguide feed pattern to be transformed into the prescribed aperture distribution. The designed system has circular aperture, left-right symmetry and no tilted structure. The continuous surface functions of reflectors are obtained by adopting the global interpolation technique to the discrete reflector profiles. Jacobi polynomial-sinusoidal is used as the basis function. A Ka-band Cassegrainian antenna operates over 17.7 – 20.2 GHz for down-link band and 27.5 – 30 GHz for up-link band is designed.

• Korean Journal of Materials Research
• /
• v.6 no.8
• /
• pp.833-840
• /
• 1996

Diamond thin films were deposited on p-type (100) Si wafers using MPECVD. Prior to deposition, ultrasonic striking was done to improve density of nucleation sites with dimond powder of 40~$60\mu$m size. Then diamond thin films were deposited at $^900{\circ}C$, 40Torr and 1000W microwave power using ${CH}_{4}$ and ${H}_{2}$ gases. The purity, the morphology and the microstructur'e and microdefects of diamond thin films were characterized by Raman spectroscopy, SEM and TEM, repectively. In Raman spectroscopy the peaks of non-diamond phase increased as ${CH}_{4}$, concentration increased. In SEM, the morphology of diamond thin films varied from crystalline to cauliflower as ${CH}_{4}$, concentration increased. As ${CH}_{4}$ con centration increased, the density of defects increased, with most defects being {III} twin. ${MTP}_{5}$, were formed with five (II]) planes. As these (Ill) Planes were twinned, ${MTP}_{5}$, represented five-fold symmetry. ]n the interfaces, defects in diamond thin films fanned out from small regions implying nucleation sites.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.20 no.4
• /
• pp.178-184
• /
• 2010

The $12CaO{\cdot}7Al_2O_3$(C12A7) powders were successfully synthesized using combustion method with microwave-assistant and C12A7:H were fabricated by post-annealed process in Ar/H atmosphere. X-ray diffraction patterns and TGDSC were used for investigating to the precursors of crystalline and reaction depending on temperature. C12A7:H that was treated post-annealed process were investigated TG-MS and Hall-measurement for confirming H ions doping and checking electrical resistivity of C12A7:H. H ion substituted to $O^{2-}$ ions in the C12A7 cages were confirmed at $289.5^{\circ}C$ by TG-MS and C12A7:H calcined at $1000^{\circ}C$ in Ar/H=8:2 atmosphere for 8~10 h has low electrical resistivity about $10^2{\Omega}{\cdot}cm$ at room temperature.

• Korean Journal of Environmental Agriculture
• /
• v.30 no.3
• /
• pp.288-294
• /
• 2011

BACKGROUND: Methylmercury is analyzed by HPLC-ICP/MS because of the simplicity for sample preparation and interference. However, most of the pre-treatment methods for methylmercury need a further pH adjustment of the extracted solution and removal of organic matter for HPLC. The purpose of this study was to establish a rapid and accurate analytical method for determination of methylmercury in fish by using HPLC-ICP/MS. METHOD AND RESULTS: We conducted an experiment for pre-treatment and instrument conditions and analytical method verification. Pre-treatment condition was established with aqueous 1% L-cysteine HCl and heated at $60^{\circ}C$ in microwave for 20 min. Methylmercury in $50{\mu}L$ of filtered extract was separated by a C18 column and aqueous 0.1% L-cysteine HCl + 0.1% L-cysteine mobile phase at $25^{\circ}C$. The presence of cysteine in mobile phase and sample solution was essential to eliminate adsorption, peak tailing and memory effect problems. Correlation coefficient($r^2$) for the linearity was 0.9998. The limits of detection and quantitation for this method were 0.15 and $0.45{\mu}g/kg$ respectively. CONCLUSION: Result for analytical method verification, accuracy and repeatability of the analytes were in good agreement with the certified reference materials values of methylmercury at a 95% confidence level. The advantage of the established method is that the extracted solution can be directly injected into the HPLC column without additional processes and the memory effect of mercury in the ICP-MS can be eliminated.

• Journal of the Korean Applied Science and Technology
• /
• v.36 no.3
• /
• pp.915-929
• /
• 2019

This study attempted to investigate the effects of natural henna-treated permanent wave on degree of damage and morphological changes of hair. For this, amino acid was analyzed, and hair thickness and surface were observed through SEM. In addition, hair curl formation & retention, methylene blue coloring, tensile strength and elongation were measured. The results found the followings: Total amino acid contents rose as the number of natural henna treatment increased, hair protection effects are expected. In terms of curl formation, in an experimental group hair became more elastic as the number of natural henna treatment increased, compared to a control group. In both control and experimental groups, hair retention decreased as shampooing frequency increased because of extension of (C) and (C)', According to analysis of hair thickness using SEM, hair became thick in an experimental group after natural henna treatment, compared to a control group. In morphological observation of hair surface, it was mostly clean, and cuticle was tidy and healthy. In methylene blue coloring, as the number of natural henna treatment increased, absorbance went up. In addition, tensile strength declined in an experimental group, compared to a control group. As the number of natural henna treatment increased, elongation in an experimental group increased, compared to a control group. The above results show that as the number of natural henna treatment increased, hair became thicker, and curl formation and retention improved. In addition, hair elasticity and flexibility were enhanced, reducing a risk of hair damage. Therefore, the study results would be available as basic data in reducing scalp and hair damage, proposing the natural henna treatment as a method to reduce hair damage from chemical perm in cosmetology industry.

• Journal of Food Hygiene and Safety
• /
• v.26 no.4
• /
• pp.322-329
• /
• 2011

This study was done to analyze the contents of minerals and vitamins to compare the measured values of minerals, vitamins with labeled values of them in food labeling and to investigate the ratio of measured values to labeled values in 437 specimen with minerals and vitamins - fortified commercial beverages and liquid teas. Content of calcium and sodium in samples after microwave digestion was analyzed with an ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer) and vitamins were determined using by HPLC (High Performance Liquid Chromatography). The measured values of calcium were ranged 80.3~142.6% of the labeled values in 21 samples composed calcium - fortified commercial beverages and liquid teas. In case of sodium, measured values were investigated 33.9~48.5% of the labeled values in 21 sports beverages. The measured values of vitamin C, vitamin $B_2$ and niacin were ranged 99.7~2003.6, 81.1~336.7, 90.7~393.2% of the labeled values in vitamins - fortified commercial beverages and liquid teas, 57, 12, 11 samples. To support achievement of the accurate nutrition label, there must be program and initiatives for better understanding and guidances on food labelling and nutrition for food manufacture.