• Journal of the Korean Geophysical Society
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• v.8 no.3
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• pp.159-167
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• 2005

Turbulent fluxes of sensible heat and latent heat were analyzed at King Sejong station in the austral summer of 2002 (December) and 2003 (January and February). Monthly mean air temperatures of January and February (2.2oC) were similar to those averaged over 1988 to 2001. Precipitation was less in January and greater in February than those averaged over last 14 years. In December of 2002 and January, there was precipitation primarily when easterly wind blew usually. The frequency of snowfall was equal to or larger than that of rainfall. In the mean while, precipitation primarily in forms of rainfall occurred with westerly wind in February. In addition, while for easterly wind, temperature and humidity was low, temperature and humidity were high in case of westerly wind. Based on flux footprint, measured flux mainly came from within 300 m with maximum of 40 m upwind, indicating the insignificant role of the sea around the study site. Half-hourly downward short wave radiation amounted up to ∼ 1000 Wm-2 and net radiation ranged from -50 to 600 Wm-2. Half-hourly sensible heat flux was positive at daytime with maximum of ∼ 400 Wm-2, except the 27th and 28th in February of 2003 when it was negative all day despite of positive net radiation at short daytime. Latent heat flux was positive with maximum of ∼ 130 Wm-2. Depending on wind direction, the partitioning of net radiation into the sum of sensible heat flux and latent heat flux was larger than 0.8, indicating the strong source of the land surface for the atmospheric heating. The daytime averaged Bowen ratio (=sensible heat flux /latent heat flux) was significantly greater than 1, indicating that sensible heat flux was the main source to heat the atmosphere over the site.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.227-230
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• 2013

The phase change of $(U_{1-x}Nd_x)_3O_8$ powder produced by oxidation of Nd-doped $UO_2$ pellet at $500^{\circ}C$ was investigated by high temperature oxidation heat treatment at $900{\sim}1500^{\circ}C$ under an air atmosphere. The XRD analysis results showed that the formation of $(U_{1-y}Nd_y)O_{2+z}$ phase and $U_3O_8$ phase from metastable $(U,Nd)_3O_8$ phase initiated at a temperature of $1000^{\circ}C$. The relative integrated intensity of $(U_{1-y}Nd_y)O_{2+z}$ phase to $U_3O_8$ phase increased with increasing of the oxidation temperature from 1100 to $1500^{\circ}C$. And also, it was found from the SEM observation that the particle size of $(U_{1-y}Nd_y)O_{2+z}$ phase increased with increasing of the oxidation temperature. However, electrone probe X-ray microanalyzer (EPMA) analysis results showed that Nd contents in $(U_{1-y}Nd_y)O_{2+z}$ phase decreased with increasing of the oxidation temperature. This behavior on the ground of XRD, SEM, and EPMA analysis data could be interpreted in terms of the transportation of U ions from $U_3O_8$ phase into $(U_{1-y}Nd_y)O_{2+z}$ phase through the interface of two phases during high temperature oxidation.

• Journal of Sensor Science and Technology
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• v.1 no.1
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• pp.59-66
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• 1992

To develop the highly sensitive TLD radiation sensors, $BaSO_{4}$ : Eu-PTFE TLDs are fabricated by polymerizing the PTFE(polytetrafluoroethylene) with $BaSO_{4}$ : Eu TL phosphors. The $BaSO_{4}$ : Eu TL phosphors having the highest sensitivity of $X/{\gamma}$-rays are obtained by sintering at $1000^{\circ}C$ in $N_{2}$ atmosphere a mixture of $BaSO_{4}$ powder with 1mol% Eu($Eu_{2}O_{3}$), 6mol% $NH_{4}Cl$ and 5mol% $(NH_{4})_{2}SO_{4}$ which were co-precipitated in dilute sulfuric acid and then dried. The activation energy, frequency factor and kinetic order of $BaSO_{4}$ : Eu TL phosphor are 1.17eV, $3.6{\times}10^{11}/sec$ and 1.25, respectively. And the spectral peak of $BaSO_{4}$ : Eu is about 425nm. The optimum TL Phosphor content and thickness of the $BaSO_{4}$ : Eu-PTFE TLD are 40wt% and $105.7mg/cm^{2}$. The optimum polymerization temperature and time for fabrication of $BaSO_{4}$ : Eu-PTFE TLDs are $380^{\circ}C$ and 2 hours in air, respectively. The linear dose range to ${\gamma}$ rays is 0.01-20Gy and fading rate is about 10%/60hours.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.69-69
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• 2002

Transgenic animals production tools have been valuable for research and purpose. The current methods of gene transfer, microinjection and nuclear transfer, which are widely used in transgenic animal production, but all most methods has only had limited success in production of larger species. Here, we report the possibility of a sperm-mediated gene transfer method in porcine embryos. Oocytes were collected from ovaries harvested at a local slaughterhouse were matured in 500${mu}ell$ drops of TCM-199 under mineral oil at 38.5$^{\circ}C$ in a humidified atmosphere of 5%CO2 in air. After 42-43h of in vitro maturation oocytes were denuded. for sperm injection into the cytoplasm of the porcine oocytes, sperm suspension in NIM medium are subjected extraction with TritonX-100 before mixing with a green fluorescent gene (GFP). Sperm with Tritonx-100 were prepared by adding TritonX-100 to a final volume of 0.05% in the sperm suspension and mixing by trituration for 60s before two wishes in NIM medium at 2$^{\circ}C$. A(ter wishing, sperm were mixed with TritonX-100 at $25^{\circ}C$ followed by washes at 2$^{\circ}C$. Sperm were resuspended in ice cold NIM to a final volume of 400${mu}ell$ and 2-20ng/${mu}ell$ DNA were triturated on ice for 60s. All microinjection was performed in HEPES-buffered CZB medium at room temperature within 2h. After culture in NCSU-23 for 72h, percent of porcine embryos transfected GFP gene are 20.7%(6/29) in 20ng/${mu}ell$ sperm-DNA mixed group and other groups were 3.7 %(2/54)and 4.7%(3/67). These data suggests that sperm-mediated gene transfer method should be used to the production tool of transgenic pig efficiently.

• Tunnel and Underground Space
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• v.25 no.1
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• pp.107-114
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• 2015

This study focuses on assessing risks which might occur in operation stage of CAES storage cavern and analyzing fire scenarios for the risk that have been assessed with highest risk level. Risks in operation stage were categorized into upper risk group and lower risk group. Components of upper risk group are technical risk, facility risk and natural disaster risk. Lower risk group is composed of 11 sub-risks. 20 experts were chosen to survey questionnaires. ANP model was applied to analyze the relative importance of 11 sub-risks. Results of risk analysis were compared with risk criterion to set risk priorities, and the highest risk was determined to be 'occurrence of the fire within the management opening'. Three fire scenarios were developed for the highest risk level and FDS (Fire dynamics Simulator) was used to analyze these scenarios. No. 3 scenario which air blows from tunnel into outside atmosphere represented that a rate of smoke spread was the fastest among three fire scenarios and a smoke descended most quickly below the limit line of breathing. Thus, No. 3 scenario turned out to be the most unfavorable condition when operating staffs were evacuated from access tunnel.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.44-52
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• 2002

Low temperature thermal desorption (LTTD) has become one of the cornerstone technologies used for the treatment of contaminated soils and sediments in the United States. LTTD technology was first used in the mid-1980s for soil treatment on sites managed under the Comprehensive Environmental Respones, Compensation and Liability Act (CERCLA) or Superfund. Implementation was facilitated by CERCLA regulations that require only that spplicable regulations shall be met thus avoiding the need for protracted and expensive permit applications for thermal treatment equipment. The initial equipment designs used typically came from technology transfer sources. Asphalt manufacturing plants were converted to direct-fired LTTD systems, and conventional calciners were adapted for use as indirect-fired LTTD systems. Other innovative designs included hot sand recycle technology (initially developed for synfuels production from tar sand and oil shale), recycle sweep gas, travelling belts and batch-charged vacuum chambers, among others. These systems were used to treat soil contaminated with total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbons (PAHs), pesticides, polychlorinated biphenyls (PCBs) and dioxin with varying degrees of success. Ultimately, performance and cost considerations established the suite of systems that are used for LTTD soil treatment applications today. This paper briefly reviews the develpoment of LTTD systems and summarizes the design, performance and cost characteristics of the equipment in use today. Designs reviewed include continuous feed direct-fired and indirect-fired equipment, batch feed systems and in-situ equipment. Performance is compared in terms of before-and-after contaminant levels in the soil and permissible emissions levels in the stack gas vented to the atmosphere. The review of air emissions standards includes a review of regulations in the U.S. and the European Union (EU). Key cost centers for the mobilization and operation of LTTD equipment are identified and compared for the different types of LTTD systems in use today. A work chart is provided for the selection of the optmum LTTD system for site-specific applications. LTTD technology continues to be a cornerstone technology for soil treatment in the U.S. and elsewhere. Examples of leading-edge LTTD technologies developed in the U.S. that are now being delivered locally in global projects are described.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.1
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• pp.21-26
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• 2011

Ni-YSZ (Yttria Stabilized Zirconia) composite powders were fabricated by glycine nitrate process. The prepared powders were sintered at $1300{\sim}1400^{\circ}C$ for 4 h in air and reduced at $1000^{\circ}C$ for 2 h in a nitrogen and hydrogen atmosphere. The microstructure, electrical conductivity, thermal expansion and mechanical properties of the Ni-YSZ cermets have been investigated with respect to the volume contents of Ni. A porous microstructure consisting of homogeneously distributed Ni and YSZ phases together with well-connected grains was observed. It was found that the open porosity, electrical conductivity, thermal expansion and bending strength of the cermets are sensitive to the volume content of Ni. The Ni-YSZ cermet containing 40 vol% Ni was ascertained to be the optimum composition. This composition offers sufficient open porosity of more than 30 %, superior electrical conductivities of 917.4 S/cm at $1000^{\circ}C$ and a moderate average thermal expansion coefficient of $12.6{\times}10^{-6}^{\circ}C^{-1}$ between room temperature and $1000^{\circ}C$.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.3243-3254
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• 2013

It is well known that increased incidences of lung, skin, and bladder cancers are associated with occupational exposure to PAHs. Animal studies show that certain PAHs also can affect the hematopoietic and immune systems and can produce reproductive, neurologic, and developmental effects. As a consequence, several studies have been attempted to investigate the fate of PAHs in atmospheric environment during the past decades. However, there is still a lack of information in regard to the atmospheric concentration of PAHs during the "Bon Fire Night". In this study, twenty-three polycyclic aromatic hydrocarbons and twenty-eight aliphatics were identified and quantified in the $PM_{10}$ and vapour range in Birmingham ($27^{th}$ November 2001-$19^{th}$ January 2004). The measured concentrations of total particulate and vapour (P+V) PAHs were consistently higher at the BROS in both winter and summer. Arithmetic mean total (P+V) PAH concentrations were $51.04{\pm}47.62$ ng $m^{-3}$ and $22.30{\pm}19.18$ ng $m^{-3}$ at the Bristol Road Observatory Site (BROS) and Elms Road Observatory Site (EROS) respectively. In addition arithmetic mean total (P+V) B[a]P concentrations at the BROS were $0.47{\pm}0.39$ ng $m^{-3}$ which exceeded the EPAQS air quality standard of 0.25 ng $m^{-3}$. On the other hand, the arithmetic mean total (P+V) aliphatics were $81.80{\pm}69.58$ ng $m^{-3}$ and $48.00{\pm}35.38$ ng $m^{-3}$ at the BROS and EROS in that order. The lowest average of CPI and $C_{max}$ measured at the BROS supports the idea of traffic emissions being a principle source of SVOCs in an urban atmosphere. The annual trend of PAHs was investigated by using an independent t-test and oneway independent ANOVA analysis. Generally, there is no evidence of a significant decline of heavier MW PAHs from the two data sets, with only Ac, Fl, Ph, An, 2-MePh, 1+9-MePh, Fluo and B[b+j+k]F showing a statistically significant decline (p<0.05). A further attempt for statistical analysis had been conducted by dividing the data set into three groups (i.e. 2000, 2001-2002 and 2003-2004). For lighter MW compounds a significant level of decline was observed by using one-way independent ANOVA analysis. Since the annual mean of $O_3$ measured in Birmingham City Centre from 2001 to 2004 increased significantly (p<0.05), it may be possible to attribute the annul reduction of more volatile PAHs to the enhanced level of annual average $O_3$. By contrast, the heavier MW PAHs measured at the BROS did not show any significant annual reduction, implying the difficulties of 5- and 6-ring PAHs to be subject to photochemical decomposition. The deviation of SVOCs profile measured at the EROS was visually confirmed during the "Bonfire Night" festival closest to the $6^{th}$ November 2003. In this study, the atmospheric PAH concentrations were generally elevated on this day with concentrations of Fl, Ac, B[a]A, B[b+j+k]F, Ind and B[g,h,i]P being particularly high.

• Atmosphere
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• v.27 no.1
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• pp.41-54
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• 2017

Organic carbon (OC) and elemental carbon (EC) in $PM_{2.5}$ were measured using Sunset OC/EC Field Analyzer at Seoul Hwangsa Monitoring Center from March to April, 2016. The mean concentrations of OC and EC during the entire period were $4.4{\pm}2.0{\mu}gC\;m^{-3}$ and $1.4{\pm}0.6{\mu}gC\;m^{-3}$, respectively. OC/EC ratio was $3.4{\pm}1.0$. The average concentrations of $PM_{10}$ and $PM_{2.5}$ were $57.4{\pm}25.9$ and $39.7{\pm}19.8{\mu}g\;m^{-3}$, respectively, which were detected by an optical particle counter. The OC and EC peaks were observed in the morning, which were impacted by vehicle emission, however, their diurnal variations were not noticeable. This is determined to be contributed by the long-range transported OC or secondary formation via photochemical reaction by volatile organic compounds at afternoon. A conditional probability function (CPF) model was used to identify the local source of pollution. High concentrations of $PM_{10}$ and $PM_{2.5}$ were observed from the westerly wind, regardless of wind speed. When wind velocity was high, a mixing plume of dust and pollution during long-range transport from China in spring was observed. In contrast, pollution in low wind velocity was from local source, regardless of direction. To know the effect of long-range transport on pollution, a concentration weighted trajectory (CWT) model was analyzed based on a potential source contribution function (PSCF) model in which 75 percentiles high concentration was picked out for CWT analysis. $PM_{10}$, $PM_{2.5}$, OC, and EC were dominantly contributed from China in spring, and EC results were similar in both PSCF and CWT. In conclusion, Seoul air quality in spring was mainly affected by a mixture of local pollution and anthropogenic pollutants originated in China than the Asian dust.

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.310-315
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• 2009

Perovskite-type ceramic powder, $La_{0.7}Sr_{0.3}Co_{0.3}Fe_{0.7}O_{3-{\delta}}$, have been synthesized successfully by the citrate method. As a result of TGA for precursor, metal-citrate complex in precursor was decomposed in the temperature range of $150{\sim}650^{\circ}C$. XRD analysis showed the single perovskite structure was observed over $1,000^{\circ}C$ without impurities. Typical dense membrane with 1.6 mm thickness has been prepared using as-prepared powder by pressing unilaterally and sintering at $1,300^{\circ}C$. The electrical conductivity of $La_{0.7}Sr_{0.3}Co_{0.3}Fe_{0.7}O_{3-{\delta}}$ membrane increased with increasing temperature at atmosphere of air and then decreased over $600^{\circ}C$ due to oxygen loss from the crystal lattice. The oxygen flux of $La_{0.7}Sr_{0.3}Co_{0.3}Fe_{0.7}O_{3-{\delta}}$ membrane in the range of 700 to $950^{\circ}C$ increased with the increasing temperature from 0.045 to $0.415ml/cm^2{\cdot}min$. The activation energy for oxygen permeation was calculated to be 89.17 kJ/mol.