• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.166-173
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• 2006

Soyasaponins are phytochemicals of major interest fur their health benefits. Chemical investigation of a soybean phytochemical concentrate resulted in the isolation and identification of triterpenoid saponins. The MeOH extraction of defatted hypocotyl separated from soybeans was peformed by the automated solvent extractor (ASE). Fractionation was performed on a flash column ($150mm{\times}40mm$ i.d.) packed with a preparative $C_{18}$ reverse phase bulk packing material $(125\AA,\;55-105{\mu}m)$ and monitored at 210 nm, and collected 14 fractions. Consequent Fsat preparative column liquid chromatography (Fast PCLC) was performed for the purification of Fraction-I (Fr-I) collected from the fraction 8 and 9 of flash chromatography. Fsat PCLC was performed on a Luna $C_{18}\;10{\mu}m,\;100{\AA}$, semipreparative reverse phase column ($250cm{\times}50mm$ i.d.) for the purification of isolated unknown compound (Fr-I-2). Chemical structure of acetyl soyasaponin $A_1\;(MW:1436.6,\;C_{67}H_{104}O_{33})$ was identified and determined by a combination of extensive NMR ($^1H-NMR$, 400 MHz; $^{13}C-NMR$, 100 MHz; DEPT), IR, UV, and ESI-MS analysis.

• Korean Journal of Materials Research
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• v.12 no.6
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• pp.452-457
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• 2002

Titanium oxide films were prepared by RF reactive magnetron sputtering. The effect of sputtering conditions on structural and optical properties was investigated systemically as a function of sputtering pressure(5~20 mTorr) and $O_2/Ar$ flow ratio(0.08~0.4). The results of the X-ray diffraction showed that all films had only the anatase $TiO_2$ phase. At low sputtering pressure and $O_2/Ar$ flow ratio, the films had preferred orientations along [101] and [200] directions. As the sputtering pressure and $O_2/Ar$ flow ratio increased, the intensity of the 101 and 200 diffraction peaks decreased gradually. The microstructure of the sputtered films showed the fine grain size (20nm~50nm) and columnar microcrystals perpendicular to the substrate. With increasing the sputtering pressure and decreasing $O_2/Ar$ flow ratio, the sputtered films showed the more porous columnar structure. XPS analysis showed that stoichiometric $TiO_2$ films were deposited at 7 mTorr sputtering pressure and 0.2 $O_2/Ar$ flow ratio. The results of the X-ray diffraction showed that all films had only the anatase $TiO_2$ phase. Ellipsometeric analysis showed that the refractive index increased from 2.32 to 2.46 as the sputtering pressure decreased. The packing density calculated using the refractive index varied from 0.923 to 0.976, indicating that $TiO_2$films became denser as the sputtering pressure decreased.

• Analytical Science and Technology
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• v.12 no.5
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• pp.370-374
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• 1999

Extraction chromatography was used to scarch optimum separation conditions of terbium. Stationary phase was 2-ethylhexyl-2-ethylhexyl phosphonic acid(HEH[EHP])levextrel (-100~+150 mesh), column size was ${\Phi}20{\times}530mm$ and kept constantly temperature at $50^{\circ}C$, adsorption flow rate of $0.2mL/cm^2{\cdot}min$, elution flow rate of $1.0mL/cm^2{\cdot}min$, column diameter to packing height of 1:15. But to search optimum separation conditions of terbium, it changed the eluent acidity, the loading weight of sample. the composition of sample. In conclusion, acidity was 0.6 N HCl, loading weight of sample was about 5% and composition of sample was $Gd_2O_3(20%)+Tb_4O_7(60%)+Dy_2O_3(20%)$. Moreover purity of separated terbium by ICP-AES analysis was 99.98% in yield of 99.99%.

• Korean Journal of Veterinary Research
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• v.41 no.3
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• pp.395-400
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• 2001

The present study analyze the morphological aspects of the cerebrum of mice with prenatal exposure to high and low dose (0.5, 1, 2 Gy) of $\gamma$-radiation on gestation day 12 or 16. The animal were allowed to give birth and the offspring were sacrificed at postnatal days 28 for gross and microscopic examination of cerebrum. Their body weight, brain weight, brain length, brain width, cortical thickness and area of cingulum bundle were examined. The histological and planimetric analysis were performed observing coronal sections. The gross malfomation (microcephaly) and abnormality of cortical architecture were prominent after exposure to 2 Gy on day 12 of gestation. significant dose-related reductions in body weight, brain weight, brain size were found in all irradiated groups. A significant change was found in thickness of the cerebral cortex and area of the cingulum bundle in the groups exposed to 0.5 Gy or more. There was no difference a lamina patter of six layers in cerebral cortex between the control and irradiated groups, but cell packing density increased significantly in the group exposed to 1 Gy or more. These results suggested that dose as low as 0.5 Gy could cause a morphologically reduce change in developing mouse cerebrum and exposure on day 12 of gestation to $\gamma$-irradiation is a particularly sensitive phase in causing malformation and abnormality of central nerve system.

• Proceedings of the Korean Society of Toxicology Conference
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• 2006.11a
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• pp.65-74
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• 2006

Modem drug discovery requires rapid pharmacokinetic evaluation of chemically diverse compounds for early candidate selection. This demands the development of analytical methods that offer high-throughput of samples. Naturally, liquid chromatography / tandem mass spectrometry (LC-MS/MS) is choice of the analytical method because of its superior sensitivity and selectivity. As a result of the short analysis time(typically 3-5min) by LC-MS/MS, sample preparation has become the rate- determining step in the whole analytical cycle. Consequently tremendous efforts are being made to speed up and automate this step. In a typical automated 96-well SPE(solid-phase extraction) procedure, plasma samples are transferred to the 96-well SPE plate, internal standard and aqueous buffer solutions are added and then vacuum is applied using the robotic liquid handling system. It takes only 20-90 min to process 96 samples by automated SPE and the analyst is physically occupied for only approximately 10 min. Recently, the ultra-high flow rate liquid chromatography (turbulent-flow chromatography)has sparked a huge interest for rapid and direct quantitation of drugs in plasma. There is no sample preparation except for sample aliquotting, internal standard addition and centrifugation. This type of analysis is achieved by using a small diameter column with a large particle size(30-5O ${\mu}$m) and a high flow rate, typically between 3-5 ml/min. Silica-based monolithic HPLC columns contain a novel chromatographic support in which the traditional particulate packing has been replaced with a single, continuous network (monolith) of pcrous silica. The main advantage of such a network is decreased backpressure due to macropores (2 ${\mu}$m) throughout the network. This allows high flow rates, and hence fast analyses that are unattainable with traditional particulate columns. The reduction of particle diameter in HPLC results in increased column efficiency. use of small particles (<2 urn), however, requires p.essu.es beyond the traditional 6,000 psi of conventional pumping devices. Instrumental development in recent years has resulted in pumping devices capable of handling the requirements of columns packed with small particles. The staggered parallel HPLC system consists of four fully independent binary HPLC pumps, a modified auto sampler, and a series of switching and selector valves all controlled by a single computer program. The system improves sample throughput without sacrificing chromatographic separation or data quality. Sample throughput can be increased nearly four-fold without requiring significant changes in current analytical procedures. The process of Bioanalytical Method Validation is required by the FDA to assess and verify the performance of a chronlatographic method prior to its application in sample analysis. The validation should address the selectivity, linearity, accuracy, precision and stability of the method. This presentation will provide all overview of the work required to accomplish a full validation and show how a chromatographic method is suitable for toxirokinetic sample analysis. A liquid chromatography/tandem mass spectrometry (LC-MS/MS) method developed to quantitate drug levels in dog plasma will be used as an example of tile process.

• Analytical Science and Technology
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• v.11 no.6
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• pp.485-494
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• 1998

Ternary and quaternary alloys composed of Mo-Ru-Rh-Pd were prepared and their crystal structure and quantitative chemical compositions were analysed by XRD, WDX, EDX and ICP/AES. The results of X-ray diffraction studies showed that the alloys were crystallized in hexagonal close packing, well known as ${\varepsilon}$-phase with $P6_3/mmc$ of space group. The optimum accelerating voltage for Zr~Cd(40~48) analyzed by EPMA using PET crystal was found to be 15 kV and the linear regression coefficient(R) of atomic number and X-ray intensity was approximately 0.998 without Tc standard specimen. The WDX results of alloys of Mo and Pd by linear regression equations were detected to be 0.1% lower compared to WDX analysis results using standard specimen, while Ru, Rh were detected 3% higher. These alloys were completely dissolved in mixed acid of 12.5 mL HCl and 1 mL $HNO_3$, at $220^{\circ}C$ for 22 hours using autoclave with PTFE vessel. There was no reprecipitating phenomnon when diluted 100 times with 1N-HCl. The results of ICP/AES analysis deviated less than 4% comparing with those of normal WDX analysis.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.3
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• pp.139-145
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• 2011

Objectives: This investigation is purposed to evaluate the airborne asbestos concentrations in the public buildings having asbestos containing materials(ACMs) in Seoul. Methods: The Seoul Metropolitan Government carried out an asbestos survey to the city-owned public buildings to identify the level of risk exposure, classified into low, moderate and high risk. To evaluate the airborne concentration of asbestos, 11 sampling sites in ten buildings based on the survey were selected. The air samples from the eleven sites were analyzed by Phase Contrast Microscopy(PCM) and Transmission Electron Microscopy (TEM), and compared the analytical results from the both. Results: 1. The airborne fiber concentrations by PCM were less than the detection limit($7f/mm^2$) in 9(82%) out of 11 sampling sites. The highest concentration was 0.0043 f/cc, but it was below the guideline value for indoor air quality(0.01 f/cc), proposed by the Ministry of Environment, Korea. 2. In two sampling sites, having moderate risk level, the chrysotile was identified and showed it's concentrations of 0.0102 s/cc and 0.0058 s/cc, less than $5{\mu}m$ lengths. 3. The ACMs identified in the two sampling sites were a packing material(65% of chrysotile) in mechanical area and a thermal system insulation(5% of chrysotile) in a boiler room. Having more possibility of asbestos emission in the mechanical area, it would be required to set up and carry out the asbestos management plan. Conclusions: Based on the result of this study, the airborne asbestos concentrations in the public buildings with ACMs were generally lower than the guideline value for indoor air quality. There are widespread concerns about the possible health risk resulting from the presence of airborne asbestos fibers in the public buildings. Most of the previous studies about airborne asbestos analysis in Korea were performed based on PCM method that asbestos and non-asbestos fibers are counted together. In the public and commercial buildings, having ACMs, it is suggested that the asbestos be analyzed by TEM method to identify asbestos due to concerns about asbestos exposure to workers and unspecified people.

• Analytical Science and Technology
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• v.11 no.3
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• pp.189-193
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• 1998

Binary alloys, $MoRu_3$ and $MoRh_3$, have been prepared using arc melting furnace. Mo and the noble metals Ru and Rh are the constituents of metallic insoluble residues, which were found in the early days of the post-irradiation studies on uranium oxide fuels. Detailed structural informations about these alloys have not been reported on JCPDS files of ICDD (International Centre for Diffraction Data). The results of X-ray diffraction study showed that the alloy was crystallized in hexagonal close-packing, well known as ${\varepsilon}$-phase. The X-ray diffraction patterns of these alloys matched well to that of $WRh_3$ with $P6_3/mmc$ of space group. The lattice parameters, a and c, were calculated using the least squares extrapolation. It was found from X-ray photoelectron spectroscopic measurements that Mo on the surface of the alloy was oxidized to Mo(6+), which could be removed by sputtering with Ar ions for approximately 15 minutes. The changes in binding energy of Mo, Ru, and Rh on the surface of the alloy were not observed. Magnetic susceptibility measurements resulted in the typical Pauli-paramagnetic behavior in the temperature range of 2 to 300 K.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.6
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• pp.327-340
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• 2017

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.