• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.904-909
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• 2012

Acid sulfate soil (ASS) and potential acid sulfate soil (PASS) are distribution in worldwide and originate from sedimentary process, volcanic activity, or metamorphism and are problematic in agriculture and environmental due to their present and potential acidity developed by the oxidation. The PASS was defined as soil materials that had sulfidic layer more than 20 cm thick within 4 m of the soil profile and contained more than 0.15% of total-sulfur (T-S). A tentative interpretative soil classification system was proposed weak potential acid sulfate (T-S, 0.15-0.5%), moderate potential acid sulfate (T-S, 0.5-0.75%) and strong potential acid sulfate (T-S, more than 0.75%). PASS due to excess of pyrite over soil neutralizing capacity are formed. It provides no information on the kinetic rates of acid generation or neutralization; therefore, the test procedures used in acid base account (ABA) are referred to as static procedures. The net acid generation (NAG) test is a direct method to measure the ability of the sample to produce acid through sulfide oxidation and also provides and indication. The NAG test can evaluated easily whether the soils is PASS. The samples are mixed sandy loam and the PAS from the hydrothermal altered andesite (1:3, 1:8, 1:16, 1:20, 1:40, 1:80 and 1:200 ratios) in this study. We could find out that the NAG pH of the soil containing 0.75% of T-S was 2.5, and that of the soil has 0.15% of T-S was 3.8. NAG pH test can be proposed as soil classification criteria for the potential acid sulfate soils. The strong type has NAG pH of 2.5, the moderate one has NAG pH of 3.0, and the weak one has NAG pH of 3.5.

• Korean Journal of Environmental Agriculture
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• v.24 no.3
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• pp.215-221
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• 2005

Numerous abandoned or closed mines are present in the steep mountain valleys in Korea due to the depression of the mining industry since the late 1980s. From the mines, enormous amounts of wastes were dumped on the slopes causing sedimentation and acid mine drainage to be discharged directly into streams causing detrimental effects on surrounding environment. Objective of this research was to evaluate the feasibility of the lime cake by-product from the soda ash production (Solvay process) to neutralize the pyrophyllite mine wastes, which have discharged the acid drainage to soil and stream in the watershed. The pH of mine wastes was strongly acidic at pH 3.67 containing over 16% of $Al_2O_3$ and 11% of $Fe_2O_3$. Whereas the lime cake by-product was strongly basic at pH 9.97 due to high contents of CaO, MgO and $CaCl_2$ as major components. Column experiments were conducted to test the neutralizing capacity of the lime cake by-product for the acidic pyrophyllite mine wastes. The column packed with the wastes (control) was treated with the lime cake by-product, calcium carbonate, the dressing soil or combination. The distilled water was eluted statically through the column and the leachate was collected for the chemical analyses. Treatments of the mine wastes with the lime cake by-product (or calcium carbonate) as mixtures increased pH of the leachate from $3.5{\sim}4.0\;to\;7{\sim}8$. Concentrations of Fe and Al in the leachate were also decreased below 1.0 mg $L^{-1}$. A Similar result was observed at the combined treatments of the mine waste, the lime by-product (or calcium carbonate) and the dressing soil. The results indicated that the lime cake by-product could sufficiently neutralize the acid drainage from the pyrophyllite mine wastes without dressing soils.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.269-269
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• 2012

A new ion source has been designed, fabricated, and installed at the NBTS (Neutral Beam Test Stand) at the KAERI (Korea Atomic Energy Research Institute) site. The goalis to provide a 100 keV, 2MW deuterium neutral beam injection as an auxiliary heating of KSTAR (Korea Super Tokamak Advanced Research). To cope with power demand, an ion current of 50 A is required considering the beam power loss and neutralization efficiency. The new ion source consists of a magnetic cusp bucket plasma generator and a set of tetrode accelerators with circular copper apertures. The plasma generator for the new ion source has the same design concept as the modified JAEA multi-cusp plasma generator for the KSTAR prototype ion source. The dimensions of the plasma generator are a cross section of $59{\times}25cm^2$ with a 32.5 cm depth. The anode has azimuthal arrays of Nd-Fe permanent magnets (3.4 kG at surface) in the bucket and an electron dump, which makes 9 cusp lines including the electron dump. The discharge properties were investigated preliminarily to enhance the efficiency of the beam extraction. The discharge of the new ion source was mainly controlled by a constant power mode of operation. The discharge of the plasma generator was initiated by the support of primary electrons emitted from the cathode, consisting of 12 tungsten filaments with a hair-pin type (diameter = 2.0 mm). The arc discharge of the new ion source was achieved easily up to an arc power of 80 kW (80 V/1000 A) with hydrogen gas. The 80 kW capacity seems sufficient for the arc power supply to attain the goal of arc efficiency (beam extracted current/discharge input power = 0.8 A/kW). The accelerator of the new ion source consists of four grids: plasma grid (G1), gradient grid (G2), suppressor grid (G3), and ground grid (G4). Each grid has 280 EA circular apertures. The performance tests of the new ion source accelerator were also finished including accelerator conditioning. A hydrogen ion beam was successfully extracted up to 100 keV /60 A. The optimum perveance is defined where the beam divergence is at a minimum was also investigated experimentally. The optimum hydrogen beam perveance is over $2.3{\mu}P$ at 60 keV, and the beam divergence angle is below $1.0^{\circ}$. Thus, the new ion source is expected to be capable of extracting more than a 5 MW deuterium ion beam power at 100 keV. This ion source can deliver ~2 MW of neutral beam power to KSTAR tokamak plasma for the 2012 campaign.

• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.284-288
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• 2001

This study was carried out to investigate the chemical properties of rainwater in Taean area. Rainwater was collected during seven months from April to October in 2000, and analyzed for its chemical composition. The pH of rainwater at April and May were higher than those from June to September. Occurrence rate of rain above pH 5.6 was 42.1%, which showed the highest ratio from rainwater samples during investigation periods. Those of pH $5.0{\sim}5.6$ and $4.5{\sim}5.0$ range were 21.1 and 31.6%, respectively. The major cation in rainwater were $Ca^{2+}$ and $NH_4\;^+$, and $SO_4\;^{2-}$ was more than 50% of total anion composition. Monthly variation of acidity neutralization capacity by $Ca^{2+}$ and $NH_4\;^+$ was decreased during rainy season. The $nss-SO_4\;^{2-}/NO_3\;^-$, ratio was 2.0 which means $SO_4\;^{2-}$ contributed to acidity of rainwater two times more than $NO_3\;^-$.

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.1
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• pp.1-5
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• 2003

This study was carried out to investigate the chemical properties of rainwater in the Suwon area. Rainwater was collected from April to October in 1999 and 2000, and its chemical composition was analyzed. The pH of rainwater in April was higher than that of the months after June. Occurrence frequency of rain above pH 5.6 was 45.1%, which showed the highest ratio from rainwater samples during the investigation periods. Those of pH 5.0∼5.6 and 4.5∼4.9 range were 31.4 and 19.6%, respectively. The major cations in rainwater were $Ca^{2+}$ and N $H_{4}$$^{+}$, and S $O_{4}$$^{2-}$ made up more than 50% of total anion composition. Monthly variation of neutralization capacity of rainwater acidity by $Ca^{2+}$ and N $H_{4}$$^{+}$ decreased during the rainy season. The ratio of non-sea salt sulfate to nitrate (nss-S $O_{4}$$^{2-}$/N $O_{3}$$^{[-10]}$ ) was 2.1, which means anthropogenic S $O_{4}$$^{2-}$ contributed to acidity of rainwater two times more than N $O_{3}$$^{[-10]}$ . .

• Journal of the Korea Concrete Institute
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• v.20 no.4
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• pp.439-449
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• 2008

Mineral admixtures are used to improve the quality of concrete and to develop sustainability of concrete structures. Supplementary cementitious materials (SCM), such as silica fume (SF), granulated blast furnace slag (GGBS) and pulverized fly ash (PFA), are gradually recognized as useful mineral admixture for producing high performance concrete. The study on ternary blended concrete utilizing mainly three major mineral admixtures is limited and the study on durability and chloride induced corrosion resistance of ternary blended concrete is very few. This study examines the durability characteristics of the ternary blended concrete composed of different amount of the SCM with ordinary Portland concrete and the study experimentally focuses on corrosion resistance evaluation of ternary blended concrete subjected to chloride attack. In this study, 50% replacement ratio of mineral admixture to OPC was used, while series of combination of $20{\sim}40%$ GGBS, $5{\sim}15%$ SF and $10{\sim}45%$ PFA binder were used for chloride corrosion resistance test. This study concerned the durability properties of the ternary blended concrete including the corrosion resistance, chloride binding, chloride transport and acid neutralization capacity. It was found that the ternary blended concrete utilizing the SCM densified the pore structures to lower the rate of chloride transport. Also, increased chloride binding and buffering to acid were observed for the ternary blended concrete with chlorides in cast.

• Molecules and Cells
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• v.44 no.10
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• pp.770-779
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• 2021

Transgenic Arabidopsis thaliana expressing an anti-rabies monoclonal antibody (mAb), SO57, was obtained using Agrobacterium-mediated floral dip transformation. The endoplasmic reticulum (ER) retention signal Lys-Asp-Glu-Leu (KDEL) was tagged to the C-terminus of the anti-rabies mAb heavy chain to localize the mAb to the ER and enhance its accumulation. When the inaccurately folded proteins accumulated in the ER exceed its storage capacity, it results in stress that can affect plant development and growth. We generated T₁ transformants and obtained homozygous T₃ seeds from transgenic Arabidopsis to investigate the effect of KDEL on plant growth. The germination rate did not significantly differ between plants expressing mAb SO57 without KDEL (SO plant) and mAb SO57 with KDEL (SOK plant). The primary roots of SOK agar media grown plants were slightly shorter than those of SO plants. Transcriptomic analysis showed that expression of all 11 ER stress-related genes were not significantly changed in SOK plants relative to SO plants. SOK plants showed approximately three-fold higher mAb expression levels than those of SO plants. Consequently, the purified mAb amount per unit of SOK plant biomass was approximately three times higher than that of SO plants. A neutralization assay revealed that both plants exhibited efficient rapid fluorescent focus inhibition test values against the rabies virus relative to commercially available human rabies immunoglobulins. KDEL did not upregulate ER stress-related genes; therefore, the enhanced production of the mAb did not affect plant growth. Thus, KDEL fusion is recommended for enhancing mAb production in plant systems.

• Journal of the Korean Applied Science and Technology
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• v.36 no.1
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• pp.165-173
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• 2019

Hydrazine[$N_2H_4$] is a typical propellant for a rocket fuel in the field of aerospace. Since it is very toxic and harmful to the environment, various environmentally-friendly propellants have been developed. In this study, relatively a safe propellant, hydroxylammonium nitrate[$NH_3OHNO_3$], was prepared via a neutralization reaction of hydroxylamine[$NH_2OH$] and nitric acid[$HNO_3$]. FT-IR was used to analyze the chemical composition, chemical structure and functional groups of HAN. Thermogravimetric analysis showed the decomposition temperature of HAN. Ion chromatography was also used to evaluate the content of nitrate ions. It was proved that the peaks of FT-IR at $3161cm^{-1}$ and $1324cm^{-1}$ indicates the functionalities of N-H and N-O present in HAN. The decomposition temperature of HAN synthesized at pH 5 to 7 was $120-140^{\circ}C$, and pH 8 resulted in higher decomposition temperature than $140^{\circ}C$. Meanwhile, the sample obtained from pH 6-7 showed the concentration of nitric acid ion with 70%.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.1
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• pp.113-125
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• 2007

To know the differences in ionic compositions in rain and snow as well as snow influence on the chemical characteristics of winter precipitation, precipitation samples were collected by the wet-only automatic precipitation sample, in winter(November-February) in the Iksan located in the northwest of Chonbuk from 1995 to 2000. The samples were analyzed for concentrations of water-soluble ion species, in addition to pH and electrical conductivity. The mean pH of winter precipitation was 4.72. According to the type of winter precipitation, the mean pH of rain was 4.67 and lower than 5.05 in snow. The frequencies of pH below 5.0 in rain were about 73%, while those in snow were about 30%. Snow contained 3 times higher concentrations of sea salt ion components originated from seawater than did rain in winter, mainly $Cl^-,\;Na^+$, and $Mg^{2+}$. Neglecting sea salt ion components, $nss-SO_4^{2-}$ and $NO_3^-$ were important anions and $NH_4^+$ and $nss-Ca^{2+}$ were important cations in both of rain and snow. Concentrations of $nss-SO_4^{2-}$ was 1.3 times higher in rain than in snow, while those of $nss-Ca^{2+}$ and $NO_3^-$ were 1.5 and 1.3 times higher in snow, respectively. The mean equivalent concentration ratio of $nss-SO_4^{2-}/NO_3^-$ in winter precipitation were 2.4, which implied that the relative contribution of sulfuric and nitric acids to the precipitation acidity was 71% and 29%, respectively. The ratio in rain was 2.7 and higher than 1.5 in snow. These results suggest that the difference of $NO_3^-$ in rain and snow could be due to the more effective scavenging of $HNO_3$ vapor than particulate sulfate or nitrate by snow. The lower ratio in snow than rain is consistent with the measurement results of foreign other investigators and with scavenging theory of atmospheric aerosols. Although substantial $nss-SO_4^{2-}$ and $NO_3^-$ were observed in both of rain and snow, the corresponding presence of $NH_4^+,\;nss-Ca^{2+},\;nss-K^+$ suggested the significant neutralization of rain and snow. Differences in chemical composition of non-sea salt ions and neutralizing rapacity of $NH_4^+,\;nss-Ca^{2+}$, and $nss-K^+$ between rain and snow could explain the acidity difference of rain and snow. Snow affected that winter precipitation could be less acidic due to its higher neutralizing rapacity.

• Economic and Environmental Geology
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• v.50 no.4
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• pp.257-266
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• 2017

Batch experiments were performed to develop the method for the pH reduction of recycled aggregate by using $scCO_2$ (supercritical $CO_2$), maintaining the pH of extraction water below 9.8. Three different aggregate types from a domestic company were used for the $scCO_2$-water-recycled aggregate reaction to investigate the low pH maintenance of aggregate during the reaction. Thirty five gram of recycled aggregate sample was mixed with 70 mL of distilled water in a Teflon beaker, which was fixed in a high pressurized stainless steel cell (150 mL of capacity). The inside of the cell was pressurized to 100 bar and each cell was located in an oven at $50^{\circ}C$ for 50 days and the pH and ion concentrations of water in the cell were measured at a different reaction time interval. The XRD and SEM-EDS analyses for the aggregate before and after the reaction were performed to identify the mineralogical change during the reaction. The extraction experiment for the aggregate was also conducted to investigate the pH change of extracted water by the $scCO_2$ treatment. The pH of the recycled aggregate without the $scCO_2$ treatment maintained over 12, but its pH dramatically decreased to below 7 after 1 hour reaction and maintained below 8 for 50 day reaction. Concentration of $Ca^{2+}$, $Si^{4+}$, $Mg^{2+}$ and $Na^+$ increased in water due to the $scCO_2$-water-recycled aggregate reaction and lots of secondary precipitates such as calcite, amorphous silicate, and hydroxide minerals were found by XRD and SEM-EDS analyses. The pH of extracted water from the recycled aggregates without the $scCO_2$ treatment maintained over 12, but the pH of extracted water with the $scCO_2$ treatment kept below 9 of pH for both of 50 day and 1 day treatment, suggesting that the recycled aggregate with the $scCO_2$ treatment can be reused in real construction sites.