• Applied Chemistry for Engineering
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• v.30 no.6
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• pp.694-697
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• 2019

In recent years, titanium dioxide powders were produced as nanoparticles or nanowires or nanotubes in one-dimensional structure, and mesoporous spheres in 3-D to improve their crystallinities, which were further used as photo-electrode materials and for preventing photo-aging. In this study, a nano sol composed of titanium dioxide exhibiting a high crystallinity was synthesized using n-alcohol as a solvent. The crystallinity of the nano sol was confirmed by FE-SEM, and XRD, while the UV blocking rate confirmed by UV-Vis spectrometry results. Changes in the crystallinity were investigated by varying the types of solvents such as butanol, propanol and ethanol. The synthesized particle sizes were from 200 to 250 nm, and the optical transmittance showed a high blocking rate in the UVB and UVA range. It is expected that a high transmittance at 550 nm wavelength can increase the photoelectric conversion efficiency of solar cells and the UV blocking efficiency.

• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.274-279
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• 2006

To synthesize ZnO colloidal solution by a sol-gel process, zinc acetate ($C_{4}H_{6}O_{4}Zn{\cdot}2H_{2}O{\cdot}0.2\;mol$) and lithium hydroxide ($LiOH{\cdot}H_{2}O{\cdot}0.14\;mol$) in the ethanol were added to the solution containing a dispersing agent, hydroxypropyl cellulose (HPC). The nanosize and physical shape of the synthesized ZnO particles were determined by HPC acting as the dispersing agent. Nanosized ZnO particles were also obtained by a precipitation method based on zinc-2-ethylhexagonate. The precipitates were characterized by DLS, XRD, FE-SEM, and UV-vis. As the results, the ZnO colloids tend to self-assemble into a well-ordered hexagonal close-packed structure. The ZnO nanoparticles have an average diameter of nearly 40 nm with a narrow size distribution.

• Proceedings of the Ginseng society Conference
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• 2002.10a
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• pp.238-252
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• 2002

In order to screen out indicators for the discrimination of ginseng habitat, some physical and chemical characteristics of Korean red ginsengs (94 kinds) and Chinese red ginsengs (50 kinds) were analyzed by using a rheometer, an electronic nose system, a combined technique of solid phase micro-extraction (SPME) and gas chromatograph equipped with an electron capture detector (GC/ECD), an X-ray fluorescence spectrometer (XRF), an inductively coupled plasma mass spectrometer (ICP/MS), a near infrared spectrometer (NIRs) and high performance liquid chromatography equipped with evaporative light scattering detector (HPLC/ELSD). The results are summarized as follows: (i) The rhizome strengths of Korean red ginsengs were significantly higher than those of Chinese red ginsengs. (ii) The electronic nose patterns of Korean red ginsengs were significantly different from those of Chinese red ginsengs. (iii) Some unidentified peaks were detected not in the headspace of Korean red ginsengs but in the headspace of Chinese red ginsengs when the headspace volatiles prepared by the SPME technique were analyzed by GC/ECD. (iv) Either the content ratios of K to Ca or Mn to Fe were significantly different between Korean red ginsengs and Chinese red ginsengs. (v) The reflectance ratios of NIRs wavenumbers such as $904\;cm^{-1}\;to\;1088\;cm^{-1}$ for Korean red ginsengs were significantly different from those for Chinese red ginsengs. (vi) The content ratios of ginsenoside-Rg to ginsenoside-Re of Korean red ginsengs were significantly higher than those of Chinese red ginsengs. These results indicate that the rhizome strength, the electronic nose pattern, the occurrence of ECD-sensitive headspace volatile components, the content ratios of K to Ca and Mn to Fe, the NIRs pattern and the content ratio of ginsenoside-Rg to -Re may be indicators for the discrimination of ginseng habitat.

• Journal of the Mineralogical Society of Korea
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• v.21 no.2
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• pp.161-175
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• 2008

The soil developed from volcanic ash in Jeju Island, Korea, were classified as typical Andisols. The soils had acidic pH, high water contents, high organic matters and clay-silty textures. The crystalline minerals of the samples were mainly composed of ferromagnesian minerals such as olivine and pyroxene, and iron oxides such as magnetite and hematite derived from basaltic materials. A large amount of gibbsite was found at the subsurface horizon as a secondary product from the migration of excessive aluminum. In addition, our study has shown that considerable amounts of poorly ordered minerals like allophane and ferrihydrite were present in Jeju soils. The contents of $SiO_2$ were lower than those of other soil orders, but $A1_2O_3$ and $Fe_2O_3$ contents were higher. These results are some of the important chemical properties of Andisols. The contents of heavy metals were in the range of $84{\sim}198$ for Zn, $56{\sim}414$ for Ni, $38{\sim}150$ for Co, $132{\sim}1164\;mg\;kg^{-1}$ for Cr, which are higher than the worldwide values in most of the soils. Some soil samples contained relatively high levels of Cr exceeding 1000 mg/kg. Mean reduction capacity of the Jeju soils was $6.53\;mg\;L^{-1}$ reduced Cr(VI), 5.1 times higher than that of the non-volcanic ash soils from inland of Korea. The soil reduction capacity of the inland soils had a good correlation with total carbon content (R = 0.90). However, in spite of 20 times higher total carbon contents in the Jeju soils, there was a week negative correlation between the reduction capacity and the carbon content (R = -0.469), suggesting that the reduction capacity of Jeju soils is not mainly controlled by the carbon content and affected by other soil properties. Correlations of the reduction capacity with major elements showed that Al and Fe were closely connected with the reduction capacity in Jeju soil (R = 0.793; R = 0.626 respectively). Moreover, the amounts of Ni, Co and Cr had considerable correlations with the reduction capacity (R = 0.538; R = 0.647; R = 0.468 respectively). In particular, in relation to the behavior of redox-sensitive Cr, the oxidation of the trivalent chromium to mobile and toxic hexavalent chromium can be restricted by the high reduction capacity in Jeju soil. The factors controlling the reduction capacity in Jeju soils may have a close relation with the andic soil properties explained by the presence of considerable allophane and ferrihydrite in the soils.

• Bulletin of the Korean Chemical Society
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• v.25 no.1
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• pp.79-84
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• 2004

The existing technological schemes for processing rhenium-containing raw materials involve the recovery of Re from solutions, which can be effectively achieved by anion exchange method. The application of anion exchange also allows to study rhenium state in aqueous solutions and to develop analytical control methods. The present work is focused on investigation of ion exchange equilibrium in the analytical system Re(VII)-HCl-$SnCl_2$-KSCN-anion exchanger by means of sorption-desorption method as well as by electron, IR- and diffuse reflection spectroscopy. It was shown that rhenium can be quantitatively recovered from this system. It is proposed to use the sorption-spectroscopic method for Re(VII) determination in aqueous solutions. The calibration curve is linear in the concentration range of 0.5-20.0 mg/L (sample volume is 25.0 mL) and the detection limit is 0.05 mg/L. The presence of Mo(VI), Cu(II), Fe(II, III), Ni(II), Zn(II) as well as $K^+,\;Na^+$ do not hinder the solid-phase determination of rhenium. Rhenium (VII) determination by diffuse reflection spectroscopy was carried out in model solutions as well as in samples of river-derived water and in solutions obtained after the dissolution of spent catalysts.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.127.2-127.2
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• 2013

오늘날 유기고분자기반 태양전지는 다른 태양전지와 비교될 정도로 낮은 광변환효율로 인해 효율향 상을 위한 많은 연구들이 진행되어 왔다. 그중 패터닝을 통한 광포집률과 charge carrier 수집효율이 증가되었다는 많은 보고들이 있었다. 따라서 우리는 200~1,400 nm polystyrene bead를 합성하여 air-liquid interfacial 방법을 이용해 2차원 육방조밀구조를 갖는 template를 형성하고 Nanosphere lithography (NSL)를 이용하여 대면적으로 균일한 poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS)를 패턴화하였다. 균일한 패턴형성을 측정하기위해 Field Emission Scanning Electron Microscopy (FE-SEM), image를 얻었으며, Atomic Force Microscopy (AFM)를 통해 형성된 패턴의 낙차 높이를 얻었고, Near IR-UV-Vis을 통해 bead size 변화에따라 얻어진 PEDOT:PSS 패턴의 반사율을 측 정하였다.

• Publications of The Korean Astronomical Society
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• v.37 no.2
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• pp.13-31
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• 2022

We observed the symbiotic star AG Dra for a total of 61 nights between April 2004 and December 2021 using the 1.8-m telescope and the high-resolution Echelle spectrograph BOES at the Bohyunsan Optical Astronomy Observatory and obtained 355 frames of spectroscopic data to investigate the variations in its spectral lines. Overnight short-term and long-term changes in prominent emission lines are examined. No short-term changes are found in the line profiles. However, the peak intensity of the Hα emission line exhibits very small variation. In the long-term period, many emission lines including He I λ5875, λ6678, λ7065 and Fe II λ5018 are found to vary reflecting the symbiotic outburst activities. It is noted that He II λ4686 and Raman-scattered O VI λ6830, λ7088 are exceptions, where no significant variations are discernible. One of the noticeable lines is the λ5018 line. Its appearance and disappearance pattern are different from other emission lines, and the line is found to appear in outburst states. The Hα and Hβ lines remain very similar in our spectroscopic monitoring campaign.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.4
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• pp.555-569
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• 2004

Size -segregated measurements of aerosol composition using 8-stage DRUM impactor are used to determine the transport of natural and anthropogenic aerosols at Gosan site from 29 March to 30 May in 2002. Separation of ambient aerosols by DRUM impactor offers many Advantages over other standard filtration techniques. Some of the most important advantages are the ability to segregate into details by particle tire, to better preserve chemical integrity since the air stream doesn＇t pars through the deposit, to collect samples as a function of time, and to have a wide variety of impaction surfaces available to match analytical needs. Although the transport of Yellow sand is a well-known phenomenon in springtime, the result of measurement shows that not only soil dust but also anthropogenic aerosols, including sulfur, enriched trace metals such as Pb, Ni, Zn. Cu, Cr, As, Se, Br, are transported to Gosan in springtime. This study combines the size- and time-resolved aerosol composition measurements with isentropic, backward air-mass trajectories in order to identify some potential source regions of anthropogenic aerosols. As a result, during the NYS period, the average concentration of PM$_{10}$ was 46$\mu\textrm{g}$/㎥, Si, Al. S, Fe, Cl, K, Ca were higher than 1,000 ng/㎥ and Ti was about 100 ng/㎥. The concentrations of Zn, Mn, Cu. Pb, Br, Rb, V, Cr, Ni. At, Se ranged between 1 and 70 ng/㎥. More than 50% typical soil elements, tuck as Al, Si, Fe, Cd. Ti, Cr, Cu, Br. were distributed in a coarse particle range(5.0-12${\mu}{\textrm}{m}$). In other hand, anthropogenic pollutants, luck as S, N, Vi, were mainly distributed in a fine particle range (0.09-0.56${\mu}{\textrm}{m}$). During the YS period, PM$_{10}$ increased about 8 times than NYS period, and main soil elements, such as Al, Si, S, K, V, Mn, Fe also doubled in coarse particle range (1.15-12${\mu}{\textrm}{m}$). But Zn, As, Pb, Cu and Se, which distributed in the time aerosols (0.09-0.56${\mu}{\textrm}{m}$), were on the same level with or decreased than NYS period. Finally. except the YS Period, coarse particles (2.5-12${\mu}{\textrm}{m}$) are inferred to be influenced by soil, coal combustion, waste incineration, ferrous and nonferrous sources through similar pathways with Yellow Sand. But fine particles have different sources, such as coal combustion, gasoline vehicle, biomass burning, oil or coal combustion, nonferrous and ferrous metal sources, which are transported from China, Korea peninsula and local sources.ces.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.6
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• pp.1244-1252
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• 1998

The purpose of this study is to evaluate the nutritional status of vitamin and minerals in the patients with alcoholic liver disease and to obtain the materials for nutritional education for alcoholics. The subjects consist of 80 patients with alcoholic liver cirrhosis(ALC) and 12 patients with alcoholic fatty liver(AFL). The control group included 57 alcoholics without liver disease(A), 32 patients with viral liver cirrhosis(VLC) and 194 normal men(NL). Biochemical evaluation of nutritional status was investigated by the analysis of blood samples. The frequency of vitamin B1 deficiency in the ALC, AFL and A groups as indicated by the erythrocyte transketolase activity coefficient were 46.0%, 66.7% and 57.9% respectively. The frequency of vitamin B2 deficiency in the ALC, AFL and A groups as indicated by the erythrocyte glutathione reductase activity coefficient were 9.8%, 8.3% and 38.6% respectively. Vitamin A deficiency was not detected in the alcoholic subjects. The frequency of vi tamin E deficiency in ALC, AFL and A were 96.3%, 66.7% and 86.0% respectively. The levels of plasma lipid peroxidation products were significantly higher in the alcoholic subjects than in the normal subjects. The frequency of subjects below normal range of hemoglobin were 85.0% in ALC, 50.0% in AFL and 31.6% in A. The frequency of copper deficiency in the ALC, AFL and A groups were 48.4%, 16.7% and 17.5% respectively. The frequency of zinc deficiency in the ALC, AFL and A groups were 83.8%, 41.7% and 66.7% respectively. Overall, the vitamin and minerals status of the alcoholic subjects in this study was evaluated to be very poor on the basis of biochemical assessments. The results suggest that alcohol abuse and poor dietary intake could cause malnutrition and may be important risk factors in causing alcoholic liver disease in alcoholics. In addition, vitamin B1, vitamin B2, Cu, Fe and antioxidant supplementation may be effective in nutritional therapy for chronic alcoholics.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.45.1-45.1
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• 2013

Type Ia supernovae (SNe Ia) are a powerful tool to investigate the expansion history of the universe, because their peak luminosity is as bright as a galaxy and is known as an excellent standard candle. Since the discovery of the acceleration of the universe based on the observations of SNe Ia, higher than ever accuracy of their peak luminosity is needed to investigate various problems in cosmology. We started a project to improve the accuracy of the calibration of the peak luminosity of SNe Ia by measuring accurate distances to nearby resolved galaxies that host SNe Ia. We derive accurate distances to the SN Ia host galaxies using the method to measure the luminosity of the tip of the red giant branch (TRGB). In this study we present the results for M66 and M96 in the Leo I Group which are nearby spiral galaxies hosting SN 1989B and SN 1998bu, respectively. We obtain VI photometry of resolved stars in these galaxies from F555W and F814W images in the Hubble Space Telescope archive. We derive the distances to these galaxies from the luminosity of the TRGB. With these results we derive absolute maximum magnitudes of two SNe (SN 1989B in M66 and SN 1998bu in M96). We derive a value of the Hubble constant from the optical magnitudes of these SNe Ia and SN 2011fe in M101 based on our TRGB analysis. This value is similar to the values derived from recent estimates from WMAP9 and Planck results, but smaller than other recent determinations based on Cepheid calibration for SNe Ia luminosity.