• Journal of the Mineralogical Society of Korea
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• v.32 no.1
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• pp.41-49
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• 2019

Probing the Na environments in Na silicate and aluminosilicate glasses is essential to the macroscopic properties of melts in the Earth. In particular, exploring the atomic structure of Na silicate and aluminosilicate glasses reveals Na-O distance, which plays an important role in transport properties of melts. Here we report the local environment around Na using $^{23}Na$ magic angle spinning (MAS) NMR. We also obtain $^{23}Na$ isotropic chemical shift (${\delta}_{iso}$) of Na silicate and aluminosilicate glasses with varying composition using Dmfit program. The Q mas 1/2 model simulates the experimental results with three simulated peaks while the CzSimple model simulates with one peak. The ${\delta}_{iso}$ decreases with increasing $SiO_2$ content in Na silicate and aluminosilicate glasses. The ${\delta}_{iso}$ increases with increasing $Na_2O$ content in Na-Ca silicate and Na aluminosilicate glasses when the $SiO_2$ content is fixed. Considering the ${\delta}_{iso}$ of Na aluminosilicate glasses available in the previous studies, together with the current simulation results, we confirm that the ${\delta}_{iso}$ has positive correlation with Al / (Al + Si). Those experimental results were reproduced better using Q mas 1/2 model. The disorder of Na in Na silicate and aluminosilicate glasses can be revealed through the simulation of 1D $^{23}Na$ MAS NMR spectra using Dmfit program in a short time.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.28 no.1
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• pp.1-18
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• 2023

The East Sea, one of the regions where the most rapid warming is occurring, is known to have important implications for the response of the ocean to future climate changes because it not only reacts sensitively to climate change but also has a much shorter turnover time (hundreds of years) than the ocean (thousands of years). However, the processes underlying changes in seawater characteristics at the sea's deep and abyssal layers, and meridional overturning circulation have recently been examined only after international cooperative observation programs for the entire sea allowed in-situ data in a necessary resolution and accuracy along with recent improvement in numerical modeling. In this review, previous studies on the physical characteristics of seawater at deeper parts of the East Sea, and meridional overturning circulation are summarized to identify any remaining issues. The seawater below a depth of several hundreds of meters in the East Sea has been identified as the Japan Sea Proper Water (East Sea Proper Water) due to its homogeneous physical properties of a water temperature below 1℃ and practical salinity values ranging from 34.0 to 34.1. However, vertically high-resolution salinity and dissolved oxygen observations since the 1990s enabled us to separate the water into at least three different water masses (central water, CW; deep water, DW; bottom water, BW). Recent studies have shown that the physical characteristics and boundaries between the three water masses are not constant over time, but have significantly varied over the last few decades in association with time-varying water formation processes, such as convection processes (deep slope convection and open-ocean deep convection) that are linked to the re-circulation of the Tsushima Warm Current, ocean-atmosphere heat and freshwater exchanges, and sea-ice formation in the northern part of the East Sea. The CW, DW, and BW were found to be transported horizontally from the Japan Basin to the Ulleung Basin, from the Ulleung Basin to the Yamato Basin, and from the Yamato Basin to the Japan Basin, respectively, rotating counterclockwise with a shallow depth on the right of its path (consistent with the bottom topographic control of fluid in a rotating Earth). This horizontal deep circulation is a part of the sea's meridional overturning circulation that has undergone changes in the path and intensity. Yet, the linkages between upper and deeper circulation and between the horizontal and meridional overturning circulation are not well understood. Through this review, the remaining issues to be addressed in the future were identified. These issues included a connection between the changing properties of CW, DW, and BW, and their horizontal and overturning circulations; the linkage of deep and abyssal circulations to the upper circulation, including upper water transport from and into the Western Pacific Ocean; and processes underlying the temporal variability in the path and intensity of CW, DW, and BW.

• Journal of Embryo Transfer
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• v.19 no.2
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• pp.89-99
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• 2004

Stretch-activated channels (SACs) responds to membrane stress with changes in open probability (Po). They play essential roles in regulation of cell volume and differentiation, vascular tone, and in hormonal secretion. SACs highly present in Xenopus oocytes and Ascidian oocytes are suggested to be involved in the regulation of pH and fluid transport to balance the osmotic pressure, but remain unclear in mammanlian oocytes. This study was investigated to find the presence of SACs in hamster oocytes and to examine their electrophysiological properties. To infer a role of SAC in relation to the development of early stage, we followed up to the stage of two-cell zygote with patch clamp techniques. Single channels were elicited by negative pressure (lower than ­15 cm$H_2O$). Interestingly, SACs were dependent on permeable cations such as $Na^+$ or $K^+$. As permeable cation removed from both sides across the membrane, SAC activity completely disappeared. When permeable cations present only in intracellular compartment, outward currents appeared at positive potentials. In contrast to this, inward currents occurred only at the negative voltage when permeable cation absent in cell interior. These result suggests that SAC carry cations through the nonselective cation channel (NSC channel). Taken together, we found that stretch activated channels present in hamster oocyte and the channel may carry cations through NSC channels. This stretch activated-NSC channels may play physiological role(s) in oocyte growth, maturation, fertilization and embryogenesis in fertilized oocytes to two-cell zygotes of hamster.

• Journal of Soil and Groundwater Environment
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• v.12 no.2
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• pp.9-19
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• 2007

This study investigated the interaction between groundwater and stream water systems, which is caused by the artificial weir on streambed, enforcing external stresses on the groundwater system. The study area is in Nami Natural Recreation Woods located in Chungcheongnam-do Geumsan-gun Nami-myeon Geoncheon-ri. In this study both of hydrophysical methods (hydraulic head) and hyrdochemical investigations (pH, EC, major ion analysis) were applied. In order to identify the relationship between each of study results, cross-correlation analysis is performed. From results of hydrophysical methods, water level fluctuation at BH-14, installed by the weir, shows the double-recession pattern much more frequently and much higher amplitudes than the fluctuation at each of other monitoring wells. Using the results by hydrochemical investigations, hydrochemical properties at BH-14 is similar to the hydrochemical characteristics in stream water. To analyze the interrelationships between the results from each of applied methods, cross-correlation analysis was applied. Results from the correlation analyses, water levels at BH-14 and stream weir showed the highest cross-correlation in hydrophysical aspects. On the other hand, the correlation between stream weir and bridge was the highest in hydrochemical aspects. The difference between the results from each of methods is due that the hydrophysical response at BH-14, such as water level, is induced by the pressure propagation-not with mass transfer, but the hydrochemical interaction, caused by mass transport, takes much more times. In conclusion impermeable artificial weir on streambed changes the interfacial condition between the stream and surrounding aquifers. The induced water flux into the groundwater system during flood period make water level at BH-14 increase instantly and groundwater quality higly similar to the quality of stream water. Referred similarities in both of water level and water quality at BH-14 become much higher when water level at weir grow higher.

• Journal of the Mineralogical Society of Korea
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• v.7 no.1
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• pp.25-39
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• 1994

The Deogbong napseok clay deposit which is composed mainly of dickite and pyrophyllite has been formed by hydrothermal alteration of the Late Cretaceous volcanic rocks consisting of andesitic tuff and andesite. The mineralogy of the napseok ores and the hydrothermal alteration processes have been studied in order to know the nature of the interaction between minerals and fluids for the formation of the deposit. Chemical distribution shows that alkali elements and silica were mobile but alumina was relatively immobile during the hydrothermal processes. It is evident that enrichment of alumina and leaching of silica from the host rock led to the formation of the napseok ore, whereas the enrichment of silica in the outer zone of the deposit gave rise to the silica zone. A large amount of microcrystalline quartz closely associated with dickite and pyrophyllite suggests the increasing activity of silica. Thus Si which was released away from the argillic zone by the increasing activity of silica. Thus Si which was released away from the argillic zone by the increasing activity of silica solubility moved out precipitating in the margin of the deposit to form the silica zone. Variation in dickite crystallinity implies the local change in the stability of the system. Thermodynamic calculation shows that the invariant point of pyrophyllite-dickite (kaolinite)-diaspore-quartz assemblages at 500 bars in the system $Al_{2}O_{3}-SiO_{2}-H_{2}O$ is about 300 $^{\circ}C$. Based on the mineral assemblages and the experimental data reported, it is estimated that the main episode of hydrothermal alteration occurred at least above 270 to 300 $^{\circ}C$ and $X_{CO_2}$ <0.025. Mineral occurrence and chemical variation indicate that the activity of Al is high in the upper part of the deposit, whereas the activity of Si is high in the lower part and the margin of the deposit. The nonequilibrium phase relations observed in the Deogbong deposit might be due to local change in intensive thermodynamic variables and fluid transport properties that resulted in the formation of nonequilibrium phases b of several stages.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.3
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• pp.430-446
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• 2018

To improve understanding of the sources and chemical properties of particulate pollutants on the Korean Peninsula, An Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) measured non-refractory fine particle ($NR-PM_1$) from 2013 to 2015 at Baengnyeong Island and Seoul metropolitan area (SMA), Korea. The chemical composition of $NR-PM_1$ in Baengnyeong island was dominated by organics and sulfate in the range of 36~38% for 3 years, and the organics were the dominant species in the range of 44~55% of $NR-PM_1$ in Seoul metropolitan area. The sulfate was found to be more than 85% of the anthropogenic origin in the both areas of Baengnyeong and SMA. Ratio of gas to particle partition of sulfate and nitrate were observed in both areas as more than 0.6 and 0.8, respectively, representing potential for formation of additional particulate sulfate and nitrate. The high-resolution spectra of organic aerosol (OA) were separated by three factors which were Primary OA(POA), Semi-Volatility Oxygenated Organic Aerosol (SV-OOA), and Low-Volatility OOA(LV-OOA) using positive matrix factorization (PMF) analysis. The fraction of oxygenated OA (SOA, ${\fallingdotseq}OOA$=SV-OOA+LV-OOA) was bigger than the fraction of POA in $NR-PM_1$. The POA fraction of OA in Seoul is higher than it of Baengnyeong Island, because Seoul has a relatively large number of primary pollutants, such as gasoline or diesel vehicle, factories, energy facilities. Potential source contribution function (PSCF) analysis revealed that transport from eastern China, an industrial area with high emissions, was associated with high particulate sulfate and organic concentrations at the Baengnyeong and SMA sites. PSCF also presents that the ship emissions on the Yellow Sea was associated with high particulate sulfate concentrations at the measurement sites.

• Korean Journal of Remote Sensing
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• v.28 no.1
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• pp.11-19
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• 2012

Air-borne pollen, biogenically created aerosol particle, influences Earth's radiative balance, visibility impairment, and human health. The importance of pollens has resulted in numerous experimental studies aimed at characterizing their dispersion and transport, as well as health effects. There is, however, limited scientific information concerning the optical properties of airborne pollen particles contributing to total ambient aerosols. In this study, for the first time, optical characteristics of pollen such as aerosol backscattering coefficient, aerosol extinction coefficient, and depolarization ratio at 532 nm and their effect to the atmospheric aerosol were studied by lidar remotes sensing technique. Dual-Lidar observations were carried out at the Gwangju Institute of Science & Technology (GIST) located in Gwagnju, Korea ($35.15^{\circ}E$, $126.53^{\circ}N$) for a spring pollen event from 5 to 7 May 2009. The pollen concentration was measured at the rooftop of Gwangju Bohoon hospital where the building is located 1.0 km apart from lidar site by using Burkard trap sampler. During intensive observation period, high pollen concentration was detected as 1360, 2696, and $1952m^{-3}$ in 5, 6, and 7 May, and increased lidar return signal below 1.5km altitude. Pollen optical depth retrieved from depolarization ratio was 0.036, 0.021, and 0.019 in 5, 6, and 7 May, respectively. Pollen particles mainly detected in daytime resulting increased aerosol optical depth and decrease of Angstrom exponent.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.1
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• pp.63-75
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• 2012

This paper gives some basic requirements and preferences of various geological environmental conditions for the final deep geological repository of spent nuclear fuel (SNF). This study also indicates how the requirements and preferences are to be considered prior to the selection of sites for a site investigation as well as the final disposal in Korea. The results of the study are based on the knowledge and experience from the IAEA and NEA/OECD as well as the advanced countries in SNF disposal project. This study discusses and suggests preliminary guideline of the disposal requirements including geological, mechanical, thermal, hydrogeological, chemical and transport properties of host rock with long term geological stabilities which influence the functions of a multi-barrier disposal system. To apply and determine whether requirements and preferences for a given parameter are satisfied at different stages during a site selection and suitability assessment of a final disposal site, the quantitative criteria in each area should be formulated with credibility through relevant research and development efforts for the deep geological environment during the site screening and selection processes as well as specific studies such as productions of safety cases and validation studies using a generic underground research laboratory (URL) in Korea.

• Journal of the Korean Applied Science and Technology
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• v.29 no.3
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• pp.450-458
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• 2012

In order to reduce the effects of greenhouse gas (GHG) emissions, the South Korean government has announced a special platform of technologies as part of an effort to minimize global climate change. To further this effort, the Korean government has pledged to increase low-carbon and carbon neutral resources for biofuel derived from biomass to replace fossil and to decrease levels of carbon dioxide. In general, second generation biofuel produced form woody biomass is expected to be an effective avenue for reducing fossil fuel consumption and greenhouse gas (GHG) emissions in road transport. It is important that under the new Korean initiative, pilot scale studies evolve practices to produce biomass-to-liquid (BTL) fuel. This study reports the quality characteristics of F-T(Fischer-Tropsch) diesel for production of BTL fuel. Synthetic F-Tdiesel fuel can be used in automotive diesel engines, pure or blended with automotive diesel, due to its similar physical properties to diesel. F-T diesel fuel was synthesized by Fischer-Tropsch (F-T) process with syngas($H_2$/CO), Fe basedcatalyst in low temperature condition($240^{\circ}C$). Synthetic F-T diesel with diesel compositions after distillation process is consisted of $C_{12}{\sim}C_{23+}$ mixture as a kerosine, diesel compositions of n-paraffin and iso-paraffin compounds. Synthetic F-T diesel investigated a very high cetane number, low aromatic composition and sulfur free level compared to automotive diesel. Synthetic F-T diesel also show The wear scar of synthetic F-T diesel show poor lubricity due to low content of sulfur and aromatic compounds compared to automotive diesel.

• Journal of the Korea Concrete Institute
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• v.18 no.5 s.95
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• pp.687-693
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• 2006

The Stone Powder Sludge(below SPS) is the by-product from the process that translates stone power of 8mm under as crushed fine aggregate. It is the sludge as like cake that has average particle size of $7{\mu}m$, absorbing water content of 20 to 60%, and $SiO_2$ content of 60% over. Because of high water content of SPS, it is not only difficult to handle, transport, and recycle, but also makes worse the economical efficiency due to high energy consuming to drying. This study is aim to recycle SPS as it is without drying. Target product is the lightweight foamed concrete that is made from the slurry mixed with pulverized mineral compounds and foams through hydro-thermal reaction of CaO and $SiO_2$. Although in the commercial lightweight foamed concrete CaO source is the cement and $SiO_2$ source is high purity silica powder with $SiO_2$ of 90%, we tried to use the SPS as $SiO_2$ source. From the experiments with factors such as foam addition rate and replacement proportion of SPS, we find that the lightweight foamed concrete with SPS shows the same trends as the density and strength of lightweight foamed concrete increases according to decrease of foam addition rate. But in the same condition, the lightweight foamed concrete with SPS is superior strength and density to that with high purity silica. This trends is distinguished according to increase of replacement proportion of SPS, also the analysis of XRF shows that the hydro thermal reaction translates SPS to tobermorite. Although SPS has low $SiO_2$ contents, the lightweight foamed concrete with SPS has superior strength and density, because it reacts well with CaO due to extremely fine particles. We conclude that it is possible to replace the high purity silica as SPS in the lightweight foamed concrete experimentally.