• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.5
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• pp.188-192
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• 2016

In this work, the SiC powders were synthesized through the carbonized matter from the mixture of silica powder and rice husks. The SiC powders, obtained from the carbothermal reduction reaction of silica and carbonized rice husks, were investigated by XRD patterns, XPS, FE-SEM and FE-TEM. In the XRD patterns, the specimens showed clearly very high strong peak of (111) plane near $35^{\circ}$ as well as weak (220) and (311) peak respectively at approximately $60^{\circ}$ and $72^{\circ}$. Under Ar atmosphere, the power synthesized from the mixture (in case of mixing ratio, 6 : 4) of carbonized rice husks and silica showed mainly cubic SiC crystalline phase showing relatively lower ratio of hexagonal phase without residual carbon in XRD pattern. In the TEM analysis, the specimen, synthesized from carbonized rice husks and silica with mixing ratio of 6 : 4 under Ar atmosphere, showed relatively fine particles under $5{\mu}m$ and a crystalline SiC phase of (100) diffraction pattern.

• Journal of Radiation Protection and Research
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• v.36 no.3
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• pp.148-153
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• 2011

EMRAS-2 (Environmental Modelling for RAdiation Safety, Phase 2) is an international comparison program, which is organized by the International Atomic Energy Agency (IAEA), in order to harmonize the modelling of radionuclide behavior in the environment. To do so, the urban contamination working group within EMRAS-2 has designed the hypothetical scenarios for a specified urban area. In this study, the importance of contaminated surfaces composing an urban environment was analyzed in terms of dose rate using METRO-K, which has been developed to take a Korean urban environment into account. The contribution of contaminated surfaces to exposure dose rate showed distinctly a great difference as a function of specified locations and time following a hypothetical event. Moreover, it showed a distinct difference according to the existence of precipitation, and its intensity. Therefore, if an urban area is contaminated radioactively by any unexpected incidents such as an accident of nuclear power plants or an explosion of radioactive dispersion devices (RDDs), appropriate measures should be taken with consideration of the type of surface composing the contaminated environment in order to minimize not only radiation-induced health detriment but also economic and social impacts.

• Journal of Korea Water Resources Association
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• v.35 no.1
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• pp.25-36
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• 2002

Window Probability Matching Method(WPMM) is achieved by matching identical probability density of rain intensities and radar reflectivities taken only from small window centered about the gage. The equation of $Z_{e}-R$ relationship is obtained and compared with data between a DWSR-88C radar and high density rain gage networks within 150km from radar site in summer season, 1998. The probability density of radar effective reflectivity is distributed with high frequency near 15dBZ. The frequency distribution of rain intensities shows that rain intensity is lower than 10mm/hr in most part of radar coverage area. As the result of $Z_{e}-R$ relationship using WPMM, curved line has shown to the log scale spatially and it can be explained more flexible than any straight-line power laws at the transformation to the rainfall amount from $Z_e$ value. During 3 months, total radar cumulative rainfall amount estimated by $Z=200R^{1.6}$ and WPMM relationships are 44 and 80 percentages of total raingage amount, respectively. Therefore, $Z_{e}-R$ relationships by WPMM may be widely needed a statistical method for the computation of accumulated precipitation.

• Journal of Life Science
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• v.20 no.5
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• pp.775-781
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• 2010

The antioxidant activities of hot water extracts from fresh, red and black garlic processed in low temperatures were compared. The chromaticity value of browning garlic was between that of fresh and black garlic. Red garlic was similar in browning intensity to fresh garlic. Also, total phenol, flavonoids, total pyruvate and thiosulfate contents were similar between fresh and black garlic. DPPH, ABTs, NO radical scavenging activity and reducing power of red garlic were significantly higher than fresh garlic, but lower than those of black garlic. $\alpha$-Glucosidase inhibitory activity in red garlic was similar to that in black garlic. Antioxidant activities of red garlic were higher than fresh garlic but lower than black garlic, and it was confirmed that antioxidant activity by production of browning material through the thermal process was the main parameter of the biological activity in the aged red garlic.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.7
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• pp.3207-3213
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• 2011

Most methods of color constancy, which is the ability to determine the object color regardless of the scene illuminant, have failed to meet our expectation of their performance especially about low-illuminated scenes. Some methods with high performance need to be developed, but we must, above all else, obtain experimental images for analyzing the required circumstances or evaluating the methods. Therefore, the paper produces new sets of images so that they can be used in the development of color constancy methods suitable for low-illuminated scenes. These sets are composed of two parts: one part of images which are synthesized with spectral power distribution(SPD) of illuminants, spectral reflectance curve of reflectances, and sensor response functions of camera; the other part of images where the intensity of each image is adjusted at the uniform rate. In an experiment, the use of the sets takes an advantage that its result images are analyzed and evaluated quantitatively as their ground truth data are known in advance.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.121-121
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• 2010

ZnO is a promising material for the application of high efficiency light emitting diodes with short wavelength region for its large bandgap energy of 3.37 eV which is similar to GaN (3.39 eV) at room temperature. The large exciton binding energy of 60 meV in ZnO provide provides higher efficiency of emission for optoelectronic device applications. Several ZnO/ZnMgO multiple quantum well (MQW) structures have been grown on various substrates such as sapphire, GaN, Si, and so on. However, the achievement of high quality ZnO/ZnMgO MQW structures has been somehow limited by the use of lattice-mismatched substrates. Therefore, we propose the optical properties of ZnO/ZnMgO multiple quantum well (MQW) structures with different well widths grown on lattice-matched ZnO substrates by molecular beam epitaxy. Photoluminescence (PL) spectra show MQW emissions at 3.387 and 3.369 eV for the ZnO/ZnMgO MQW samples with well widths of 2 and 5 nm, respectively, due to the quantum confinement effect. Time-resolved PL results show an efficient photo-generated carrier transfer from the barrier to the MQWs, which leads to an increased intensity ratio of the well to barrier emissions for the ZnO/ZnMgO MQW sample with the wider width. From the power-dependent PL spectra, we observed no PL peak shift of MQW emission in both samples, indicating a negligible built-in electric field effect in the ZnO/$Zn_{0.9}Mg_{0.1}O$ MQWs grown on lattice-matched ZnO substrates.

• Journal of The Korean Ophthalmological Society
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• v.59 no.11
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• pp.1071-1076
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• 2018

Purpose: To report a case of immunoglobulin G4 (IgG4)-related ophthalmic disease associated with adult xanthogranulomatous disease. Case summary: A 38-year-old male with a history of cholecystectomy visited our clinic for bilateral periorbital swelling. Histopathology of the orbital biopsy showed diffuse infiltration of foamy histiocytes with Touton giant cells and lymphoid follicles, with a diagnosis of adult-onset xanthogranuloma. After excisional biopsy, he was treated with azathioprine and prednisolone. Four years after treatment, he again visited the clinic due to bilateral, yellowish eyelid masses. Serological examinations were all nonspecific findings, except for elevation of IgG and IgG4 levels. Magnetic resonance imaging showed bilateral symmetric soft tissue enlargement with slightly heterogeneous T1/T2 isosignal intensity, with contrast enhancement at the superolateral aspect of extraconal spaces. Excisional biopsy and blepharoplasty were performed. Immunohistochemical sections showed that the IgG4+/IgG plasma cell ratio was 10-20% and the IgG4 plasma cell count was 22/high power field (HPF). His past sections of 2013 from the pathology department were again stained and showed that the IgG4+/IgG plasma cell ratio was 40-50% and the IgG4 plasma cell count was 59/HPF. Thus, he was definitely diagnosed with IgG4-related ophthalmic disease. Conclusions: If there is recurrent eyelid swelling, IgG4-related ophthalmic disease should be considered as a differential diagnosis. And the patient with adult xanthogranulomatous disease can be diagnosed with IgG4-related ophthalmic disease.

• Korean Journal of Remote Sensing
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• v.21 no.4
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• pp.303-316
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• 2005

Strong radar returns were observed in oyster sea farms, and coherent interferometric pairs were successfully constructed. Tide height in coastal area is possible to be measured by using interferometric phase and intensity of SAR data. This SAR application technique for measuring the tide height in the near coastal zone can be further improved when applied to double bounce dominant areas. In this paper, we investigate the characteristics of polarimetric signature in the oyster farm structures. Laboratory experiments were carried out using Ku-band according to the target scale. Radar returns from vertical poles are stronger than those from horizontal Pole by 10.5 dB. Single bounce components were as strong as double bounce components and more sensitive to antenna look direction. Double bounce components show quasi-linear relation with the height of vertical poles, which implies double bounce is more useful to determine water level than total power. A L-band NASA/IPL airborne SAR (AIRSAR) image was classified into single-, double-bounce, and volume scattering components. It is observed that oyster farms are not always characterized by double bounced scattering. Double bounce is a main scattering mechanism in oyster farms standing above seawater, while single bounce is stronger than double bounce when bottom tidal flats are exposed to air. Ratios of the normalized single to double bounce components in the former and latter cases were 0.46 and 5.62, respectively. It is necessary to use double bounce dominant sea farms for tide height measurement by DInSAR technique.

• Economic and Environmental Geology
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• v.52 no.5
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• pp.485-497
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• 2019

The Jade Investiture Books in Joseon Dynasty shows diverse facies with various petrographic characteristics to green and white based on color. In lithologically, the green rocks are jade composed of calcite and serpentine, and the white ones are marbles consisting mainly in crystalline calcite. As a result of X-ray diffraction of jade rocks, the more green in color, the more increased intensity of serpentine appears. Therefore, the grade of jade is correlated with contents of serpentine. The Jade Investiture Books owned by the National Palace Museum of Korea are subdivided with 104 (41.3%) books made by only jade rocks, 98 (38.9%) books made by only marbles, and 50 (19.8%) books mixed with jade rocks and marbles. Among the mixed ones, 47 (18.6%) books consisted mainly of the marbles. This result shows the superior marble books occupy more than half of the total books. The Jade Investiture Books made in early Joseon Dynasty are composed of high grade jade. However, the grade of jade had decreased as the kings changed in process of time, and the composition of marble had increased in reverse proportion of jade. The quality of letter pigments, metal accessories and fabrics also had decreased with jade. These trends are reflected in the aspect of society such as weakening royal authority, national power and finance with the course of time. The jade of the books has different mineralogical characteristics from some modern jade produced in Chuncheon nephrite and Buyeo precious serpentine in Korea. Meanwhile, there is ancient literature that described quarries from Namyang in Hwaseong of Gyeonggi province. This area has a wide distribution of gneiss, limestone and limesilicate rocks are interbedded between muscovite schist. The limesilicate rocks contain diopside, which produced serpentine through alteration. It has possibility to make the Jade Investiture Books using these small amounts of jade through mining activity.

• Journal of Mushroom
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• v.19 no.3
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• pp.216-224
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• 2021

This study analyzed food component characteristics and antioxidant activities in five kinds of domestic commercial shiitake mushrooms (Lentinula edodes). Moisture content (79.17-82.90 g/100 g) showed little difference, but there was a significant difference in crude protein content. Total mineral content showed a significant difference, and potassium (K) content was the highest. Total and essential amino acid contents were higher in mushroom A than in the other samples. Nonetheless, the ratios of essential amino acids, aspartic acid, and glutamic acid to total amino acids were similar in all samples. 𝛽-Glucan content was in the range of 10.28-5.68 g/100 g, exhibiting a significant difference. The color intensity and overall texture of the mushrooms showed no remarkable difference. Total phenol and flavonoid contents were in the range of 19.92-30.77 mg/100 g and 6.95-10.39 mg/100 g, respectively; the ratio of flavonoids to total phenols ranged from 31.53% to 38.21%. DPPH and ABTS radical scavenging activities were 74.92-79.04% and 80.47-84.97%, respectively, and showed little difference. However, the reducing power varied between 195.23 𝜇M and 317.85 𝜇M, displaying a significant difference in all samples. Therefore, this study observed similar trends in the food component characteristics and antioxidant activities of domestic commercial shiitake mushrooms.