• Journal of the Mineralogical Society of Korea
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• v.21 no.1
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• pp.57-65
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• 2008

The geochemical partitioning of arsenic in contaminated soils from a of wet land and tailing of the abandoned mine is examined. Chemical analysis and sequential extraction method by ultrasound-sonication extraction are applied to investigate the mobility and chemical existence conditions of arsenic as well as heavy metals. The results of this study showed that heavy metals concentration of tailings showed as a following order: Fe > As > Cu > Pb > Cr. The highest metal concentration was recognized in samples less than $63\;{\mu}m$ fraction in their particle sizes. Exchangeable and carbonate fractions in soil samples showed following Cu > As > Pb > Fe > Cr for tailings, and Fe > Pb > Cu > As > Cr for reservoir soils, respectively. Arsenic was bound as exchangeable fraction in tailings and its concentration appeared higher than those of the other metals. Thus, As can be easily dispersed into soil and water environments. The obtained results can be used to design soil remediation plan in the study area and require further detailed study to investigate severe environmental pollution of surface water as well as rivers with respect to heavy metals in terms of speciation analysis of toxic elements such as As and Cr.

• Journal of Astronomy and Space Sciences
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• v.22 no.4
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• pp.473-482
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• 2005

Many technical challenges are being tried for a large space infrared telescope, which is one of the major objectives of the Strategic Technology Road Map (STRM) of KASI (Korea Astronomy and Space Science Institute), As one of these challenges, KASI and KBSI (Korea Basic Science Institute) have started a cooperation project for developing a space infrared cryogenic system with KIMM (Korea Institute of Machinery as Materials) and i3system co. In this paper, we generate optical requirements for the Protomodel of Space Infrared Cryogenic System (PSICS), and design a single lens optical system with a bandpass of $3.8\~4.8{\mu}m$, a field of view of $15^{\circ}\times12^{\circ}$, and an angular resolution of $0.047^{\circ}$, to develop a further complex optical system.

• Korean Journal of Microbiology
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• v.45 no.3
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• pp.268-274
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• 2009

A photosynthetic cyanobacterium Arthrospira platensis, well known for health food supplement, was studied as a target species for atmospheric $CO_2$ removal as well as biomass production. Although the biomass of A. platensis was massively produced in many countries, the recovery cost of its biomass is still high. The purpose of this study was to develop the A. platensis mutant strains which have enhanced growth rate and floatation activity to reduce the recovery cost. A. platensis KCTC AG20590 was treated with 0.24% ethyl methanesulfonate (EMS) for 20 min at room temperature. The mutant strain A. platensis M20CJK3 was finally selected by its morphological and physiological features. The morphology of the mutant A. platensis M20CJK3 was changed from loose-coiled form to tight-coiled form showing short pitch. The growth and $CO_2$ uptake rate of A. platensis M20CJK3 were improved about 15% and 17% compared with A. platensis KCTC AG20590, respectively. The floatation activity of A. platensis M20CJK3 was enhanced in 2-fold compared with that of A. platensis KCTC AG20590. Soluble proteins extracted from two strains were analyzed by two dimensional electrophoresis (2-DE) and MALDI-TOF MS/MS. Among 15 protein spots induced in 2-DE analysis, two spots were the proteins related to photosynthesis and electron transfer system of the other cyanobacteria. As a consequence, it seems that the tight-coiled mutant A. platensis M20CJK3 has an advantage of high growth rate and floatation activity which are beneficial for the mass cultivation and recovery.

• Korean Journal of Environmental Agriculture
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• v.19 no.1
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• pp.75-79
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• 2000

To investigate seasonal variations of soil solution chemistry, samples were collected from zero tension lysimeters in O, A, and B horizons of 26-year-old Larix leptolepis. Pinus koraiensis and Quercus mongolica stands in Kwangju, Kyunggi Province from September, 1996 through June. 1999. Potassium, $Mg^{2+}$, $Cl^-$, and $No_3\;^-$ concentrations increased in October and November concurrent with inputs of fresh litterfall and twigs. Sodium, $Ca^{2+}$, $K^+$, and $Mg^{2+}$ concentrations increased in March and April concurrent with the yellow sand effect. Potassium concentration showed the highest variation among ions, and $Cl^-$ concentration showed positive correlations with $K^+$ and $Mg^{2+}$ concentrations. Soil solution pH decreased while $Al^{3+}$ and $K^+$ concentrations increased during the study period. If our data reflects long term trends. then $Al^{3+}$ concentration in the O horizon will reach the toxic level (0.180 meq/l) within 10-20 years depending on species.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.47-52
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• 2012

Porous carbon nanofibers were prepared as a gas sensor electrode to study the $CO_2$ sensing property based on effects of porosity and introduced amine functional groups. Electrospun fibers were obtained by using electrospinning method with polyacrylonitrile precursor and they were treated by the thermal treatment and chemical activation. Amine functional groups were introduced by the liquid state treatment using diethylenetriamine. The specific surface area increased up to $2000m^2/g$ by the chemical activation. The Introduced amine functional group was identified using FT-IR spectroscopy. $CO_2$ gas sensing property was improved as four folds via introduced amine functional groups on the activated carbon nanofiber. In conclusion, the gas sensing property was improved based on the developed porosity by the chemical activation and the chemical attraction of $CO_2$ gas by introduced functional groups.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.479-486
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• 2009

In natural environments, manganese (Mn) exists in the valence of +2, +3, and +4 and plays a pivotal role as a strong oxidant or reductant in the geochemical cycles of elements. Especially, Mn forms varying (oxyhydr)oxides. The oxidation state of structural Mn is characteristic to each oxide and is one of the most important factors controlling its geochemical behaviors such as solubility, sorption capacity, and redox potential. Therefore, it is important to elucidate processes governing Mn oxidation state in predicting the fate and transport of many redox sensitive elements in the environment. X-ray photoelectron spectroscopy (XPS) is a very useful method to determine the oxidation state of various elements in solid phases. In this study, the oxidation states of structural Mn in MnO, $Mn_2O_3$, $MnO_2$ were assessed based on the binding energy spectra of $Mn2p_{3/2}$ and Mn3s using XPS and were compared with those reported elsewhere. $Mn2p_{3/2}$ binding energies were determined as 640.9, 641.5, 641.8 eV for MnO, $Mn_2O_3$, $MnO_2$, respectively, which indicates that the binding energy increased with increasing Mn oxidation state. It was also noted that Ar etching may cause changes in electronic structure configuration on surface of the original sample.

• Korean Journal of Materials Research
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• v.15 no.3
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• pp.161-165
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• 2005

We investigated selective dry etching of GaAs over AlGaAs and InGaP in high density planar inductively coupled $BCl_3/SF_6$ plasmas. The process parameters were ICP source power (0-500 W), RE chuck power (0-30W) and gas composition $(60-100\%\;BCl_3\;in\;BCl_3/SF_6)$. The process results were characterized in terms of etch rate, selectivities of GaAs over AlGaAs and InGaP, surface morphology, surface roughness and residues after etching. $BCl_3/SF_6$ selective etching of GaAs showed quite good results in this study. Selectivities of GaAs $(GaAs:AlGaAs\~36:1,\;GaAs:InGaP\~45:1)$ were superior at $18BCl_3/2SF_6$, 20 W RF chuck power, 300 W ICP source power and 7.5 mTorr. Addition of $(5-15\%)SF_6\;to\;BCl_3$ produced relatively high selectivities of GaAs over AlGaAs and InGaP during etching due to decrease of etch rates of AlGaAs and InGaP (boiling points of etch products: $AlF_3\~1300^{\circ}C,\;InF_3>1200^{\circ}C$ at atmosphere) at the condition. SEM and AFM data showed slightly sloped sidewall and somewhat rough surface$(RMS\~9nm)$. XPS study on the surface of processed GaAs proved a very clean surface after dry etching. It shows that planar inductively coupled $BCl_3/SF_6$ plasmas could be a good candidate for selective dry etching of GaAs over AlGaAs and InGaP.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.3
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• pp.239-247
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• 2018

Chronic inflammation is known to have effects on various diseases such as gout, cancer, dementia, atopic disease, and obesity. In addition, since some signal cascades involved in the development of inflammation are known to affect the damage and aging of the skin tissue, studies are being conducted actively to control the inflammation mechanism. In order to mitigate or prevent inflammatory response, a number of researches have been made to develop anti-inflammatory materials from some plants. In particular, Stevia rebaudiana produces steviol glycosides (SG), a natural sweetener with a distinctive flavor. Studies on some of SG have been shown to have anti-inflammatory activity. Researchers of this study expected that more SG also possess anti-inflammatory activity, besides stevioside, rebaudioside A, and steviol. In order to confirm this possibility, the researchers screened inhibition activity of various steviol glucosides for NO production in RAW 264.7 cell lines. As a result, steviol ${\beta}-glucopyranosyl$ ester (SGE) showed the highest inhibitory activity among steviol derivatives treated at the same molar concentration. In addition, we found that mRNA expression level of $interleukin-1{\alpha}$ ($IL-1{\alpha}$), $interleukin-1{\beta}$ ($IL-1{\beta}$), cyclooxygenase-2 (COX-2), nuclear factor kappa-light chain-enhancer of activated B cells ($NF-{\kappa}B$) and inducible nitric oxide synthase (iNOS) was also decreased in a dose-dependent manner. These results show that SGE inhibits anti-inflammatory activity and NO production in mouse macrophage RAW 264.7 cells. It was confirmed that SGE has potential to be applied as an anti-inflammatory material.

• Economic and Environmental Geology
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• v.53 no.4
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• pp.383-395
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• 2020

The stratigraphical position of the Haengmae Formation can provide clues towards solving the hot issue on the Silurian formation, also known as Hoedongri Formation. Since the 2010s, there have been several reports denying the Haengmae Formation as a lithostratigraphic unit. This study aimed to clarify the lithostratigraphic and chronostratigraphic significance of the Haengmae Formation. The distribution and structural geometry of the Haengmae Formation were studied through geologic mapping, and the correlation of relative geologic age and the absolute age was performed through conodont biostratigraphy and zircon U-Pb dating respectively. The representative rock of the Haengmae Formation is massive and yellow-yellowish brown pebble-bearing carbonate rocks with a granular texture similar to sandstone. Its surface is rough with a considerable amount of pores. By studying the mineral composition, contents, and microstructure of the rocks, they have been classified as pebble-bearing clastic rocks composed of dolomite pebbles and matrix. They chiefly comprise of euhedral or subhedral dolomite, and rounded, well-sorted fine-grained quartz, which are continuously distributed in the study area from Biryong-dong to Pyeongan-ri. Bedding attitude and the thickness of the Haengmae Formation are similar to that of the Hoedongri Formation in the north-eastern area (Biryong-dong to Haengmae-dong). The dip-direction attitudes were maintained 340°/15° from Biryong-dong to Haengmae-dong with a thickness of ca. 200 m. However, around the southwest of the studied area, the attitude is suddenly changed and the stratigraphic sequence is in disorder because of fold and thrust. Consequently, the formation is exposed to a wide low-relief area of 1.5 km × 2.5 km. Zircon U-Pb age dating results ranged from 470 to 449 Ma, which indicates that the Haengmae Formation formed during the Upper Ordovician or later. The pebble-bearing carbonate rock consisted of clastic sediments, suggesting that the Middle Ordovician conodonts from the Haengmae Formation must be reworked. Therefore, the above-stated evidence supports that the geologic age of the Haengmae Formation should be Upper Ordovician or later. This study revealed that the Haengmae Formation is neither shear zone, nor an upper part of the Jeongseon Limestone, and is also not the same age as the Jeongseon Limestone. Furthermore, it was confirmed that the Haengmae Formation should be considered a unit of lithostratigraphy in accordance with the stratigraphic guide of the International Commission on Stratigraphy (ICS).

• Journal of the Korean Society of International Agriculture
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• v.23 no.5
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• pp.537-545
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• 2011

This study was conducted to obtain basic information on physiological and proteomic responses of barley seedlings to salt stress. Shoot dry weight decreased significantly as the level of soil salinity increased. Salt stress-induced decrease of relative shoot dry weight was lower in cv. "Sanglok" than in cv. "Sunwoo". Under the salt stress, SPAD value decreased, and the value was higher in cv. "Sanglok" than in cv. "Sunwoo". Sodium ion content in the leaves increased as NaCl concentration increased, and the content was higher in cv. "Sunwoo" than in cv. "Sanglok". The K⁺/Na⁺ ratio was higher in cv. "Sanglok" than in cv. "Sunwoo". Salt stress-induced alterations in protein expression of the leaves were detected by two dimensional electrophoresis, and 47 protein spots showing altered expression were selected. Among the selected protein spots, 17 protein spots were up-regulated and 28 spots down-regulated in cv. "Sanglok". In cv. "Sunwoo", 14 protein spots were up-regulated and 27 spots down-regulated. Out of 47 deferentially expressed protein spots, 18 protein spots were identified using mass spectrometry and NCBI protein database. Among the identified proteins, ten proteins are known to be involved in various stress responses, but the others are not directly involved in stress responses.