• Journal of Soil and Groundwater Environment
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• v.19 no.2
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• pp.7-15
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• 2014

This study was conducted to understand the chemical characteristics of groundwater in carbonate areas of Korea. In this study, data on pH, electric conductivity (EC), $Ca^{2+}$, $Mg^{2+}$, $Na^+$, $K^+$, $Cl^-$, $SO_4{^{2-}}$, and $HCO_3{^-}$ were collected from 97 wells which were installed in various carbonate rock regions of Korea. The pH values ranged from 5.7 to 9.9, and the average value was 7.3. The concentration range showed differences between the maximum value of $HCO_3{^-}$ and the medium to minimum values of $Ca^{2+}$, $Mg^{2+}$, $Na^+$, $Cl^-$, $SO_4{^{2-}}$, and $K^+$ in the study area. The average value of EC was $374{\mu}S/cm$, higher than in granite and gneiss areas, where the value is $176{\mu}S/cm$. Most of the groundwater was type $Ca-HCO_3$, and some was type $Mg-HCO_3$. The relationship between $Ca^{2+}$, $Cl^-$, and $HCO_3{^-}$, respectively, and EC showed relatively significant positive correlations compared to the other dissolved components. However, the determination coefficients for $Mg^{2+}$, $Na^+$, $SO_4{^{2-}}$, and $K^+$ were very low less than 0.2. These results indicate that the source of $Ca^{2+}$ and $Mg^{2+}$ is relatively simple (carbonate dissolution) compared to other sources. The sources of $Na^+$, $K^+$, $Cl^-$, $SO_4{^{2-}}$, and $HCO_3{^-}$ might be not only water-rock interactions, but also irrigation return flow, because many groundwater wells had been developed for irrigation purposes. Subsequently, the influence of agriculture on groundwater chemistry was evaluated using a cumulative plot of $SO_4{^{2-}}$. The threshold value of $SO_4{^{2-}}$ calculated from the cumulative frequency curve was 29.2 mg/L. Therefore, 12.4% of all the groundwater wells were affected by agricultural activity.

• Journal of Korean Society of Forest Science
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• v.59 no.1
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• pp.67-91
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• 1983

In order to examine the alcohol production from softwoods (Pinus densiflora Sieb. et Zucc., Pinus rigida Miller, Larix leptolepis Gordon) and hardwoods (Alnus japonica Steud., Castanea crenata Sieb. et Zucc. Populus euramericana CV 214), chemical compositions were analyzed and conditions of acid hydrolysis with wood meals were established. Also strains which could remarkably decompose the cellulose were identified, and conditions of cellulase production of strains, characteristics of cellulase, and alcohol fermentation were examined. The results were summarized as follows. 1) In acid hydrolysis of wood, the high yield of reducing sugars was shown from 1.0% to 2.0% of hydrochloric acid and 2.0% of sulfuric acid. The highest yield was produced 23.4% at wood meals of Alnus japonica treated with 1.0% of hydrochloric acid. 2) The effect of raising the hydrolysis was good at $1.5kg/cm^2$, 30 times (acid/wood meal), and 45 min in treating hydrochloric acid and 30 min in treating sulfuric acid. 3) The pretreatments with concentrated sulfuric acid were more effective concentration ranged from 50% to 60% than that with hydrochloric acid and its concentration ranged from 50% to 60%. 4) The quantative analysis of sugar composition of acid hydrolysates revealed that glucose and arabinose were assayed 137.78mg and 68.24mg with Pinus densiflora, and 102.22mg and 65.89mg with Alnus janonica, respectively. Also xylose and galactose were derived. 5) The two strains of yeast which showed remarkably high alcohol productivity were Saccharomyces cerevisiae JAFM 101 and Sacch. cerevisiae var. ellipsoldeus JAFM 125. 6) The production of alcohol and the growth of yeasts were effective with the neutralization of acid hydrolysates by $CaCO_3$ and NaOH. Production of alcohol was excellent in being fermented between pH 4.5-5.5 at $30^{\circ}C$ and growth of yeasts between pH 5.0-6.0 at $24^{\circ}C$. 7) The production of alcohol was effective with the addition of 0.02% $(NH_2)_2CO$ and $(NH_4)_2SO_4$, 0.1% $KH_2PO_4$, 0.05% $MgSO_4$, 0.025% $CaCl_2$, 0.02% $MnCl_2$. Growth of yeasts was effective with 0.04-0.06% $(NH_2)_2CO$ and $(NH_4)_2SO_4$, 0.2% $K_2HPO_4$ and $K_3PO_4$, 0.05% $MgSO_4$, 0.025% $CaCl_2$, and 0.002% NaCl. 8) Among various vitamins, the production of alcohol was effective with the addition to pyridoxine and riboflavin, and the growth of yeasts with the addition to thiamin, Ca-pantothenate, and biotin. The production of aocohol was increased in 0.1% concentration of tannin and furfural, but mas decreased in above concentration. 9) In 100ml of fermented solution, alcohol and yeast were produced 2.201-2.275ml and 84-114mg for wood meals of Pinus densiflora, and 2.075-2.125ml and 104-128mg for that of Alnus japonica. Residual sugars were 0.55-0.60g and 0.60-0.65g for wood meals of Pinus densiflora and Alnus japonica, respectively, and pH varied from 3.3 to 3.6. 10) A strain of Trichoderma viride JJK. 107 was selected and identified as its having the highest activity of decomposing cellulose. 11) The highest cellulase production was good when CMCase incubated for 5 days at pH 6.0, $30^{\circ}C$ and xylanase at pH 5.0, $35^{\circ}C$. The optimum conditions of cellulase activity were proper in case of CMCase at pH 4.5, $50^{\circ}C$ and xylanase at pH 4.5, $40^{\circ}C$. 12) In fermentation with enzymatic hydrolysates, the peracetic acid treatment for delignification showed the best yields of alcohol and its ratio was effective with the addition of about 10 times. 13) The production of alcohol was excellent when wood meals and Koji of wheat bran was mixed with 10 to 8 and the 10g of wood meals of Pinus densiflora produced 2.01-2.14ml of alcohol and Alnus japonica 2.11-2.20ml.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.489-492
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• 2000

The rejection of hardness in a lactate fermentation broth was investigated by NTR-729 nanofiltration membrane. Firstly, a method for determining membrane surface charge was proposed on the basis of the rejection data for NaCl, $Na_2SO_4$, $MgCl_2$, $MgSO_4$ solutions. It was found that the NTR-729 membrane was negatively charged. The rejection of $Mg^{2+}$ ions in model solution of lactate was over 80% with lactate concentrations. But the rejection of $Mg^{2+}$ ions in fermentation broth of lactate was about 40 %. This results was caused by anions paired with $Mg^{2+}$ ions. It was found that the repulsive force of monovalent anions with membrane was almost few through an experiment of a mixed solution of NaCl/ $Na_2SO_4$. So the rejection of $Mg^{2+}$ ion in a fermentation broth was lower than that in a model solution because $Mg^{2+}$ ions permeated to the membrane with various monovalent anions.

• Journal of environmental and Sanitary engineering
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• v.15 no.1
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• pp.102-108
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• 2000

Seasonal variation of $NO_2$ and $SO_2$ concentration was investigated at the underground shopping center in Chonan from October 1997 to August 1998. $NO_2$ and $SO_2$ was collected by personal air sampler at $0.4{\ell}/min$ and $0.5{\ell}/min$ respectively and analyzed using UV spectrophotometer at 550nm and 548nm individually. The results were as follows. 1. The concentration of $NO_2$ was 0.070 ppm in spring, 0.068 ppm in summer, 0.074 ppm in autumn and 0.085 ppm in winter. There was no significant difference. 2. The concentration of $SO_2$ was 0.0233 ppm in spring, 0.0216 ppm in summer, 0.0188 ppm in autumn and 0.0621 ppm in winter. There was significant difference (p<0.01). 3. The higher concentration of $NO_2$ and $SO_2$ gases were shown near the cafeteria (p<0.001, p<0.05). 4. The higher concentration of $NO_2$ was observed at indoor than the underground passage. There was significant difference between two values (p<0.01).

• The KIPS Transactions:PartA
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• v.15A no.1
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• pp.61-68
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• 2008

In this paper, we propose the VLSI design of Multi-Format Video Decoder (MFD) to support video codec standards such as MPEG-2, MPEG-4, H.264 and VC-1. The target of the proposed MFD is the Full HD (High Definition) video processing needed for the high-end D-TV SoC (System-on-Chip). The size of the design is reduced by sharing the common large-size resources such as the RISC processor and the on-chip memory among the different codecs. In addition, a detachable architecture is introduced in order to easily add or remove the codecs. The detachable architecture preserves the stability of the previously designed and verified codecs. The size of the design is about 2.4 M gates and the operating clock frequency is 225MHz in the Samsung 65nm process. The proposed MFD supports more than Full-HD (1080p@30fps) video decoding, and the largest number of video codec standards known so far.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.686-691
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• 2008

There are no many research reports on the preparation of ZnO by electrochemical oxidation since the zinc oxide is very easily dissolved in an acidic or basic environment, even though zinc oxides have attracted many attentions because of their optical/electrical properties. In this paper, we describe the fabrication of self-ordered stripes of ZnO by anodization of Zn in an ethanolic sulfuric acid. The formation of stripes of ZnO originating from Zn is attributed to water-selective dissolution of ZnO during anodization. We study in detail the effects of concentration of $H_2SO_4$, applied potential, anodization time, and addition of a small amount of water on the fabrication of stripes of ZnO. Mechanisms for the fabrication of ZnO stripes are discussed in terms of the above-mentioned effects.

• Journal of Korea Soil Environment Society
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• v.4 no.1
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• pp.75-83
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• 1999

The purpose of this study is to investigate the chemical characteristics of the leachate for the open(illegal) dumping waste. In this study, the open dumping waste were mixed with 0, 5, 10, 15% of bentonite in each Iysimeter as a rate of weight. The simulation was evaluated by CODcr, ${NO_3}^-$, ${SO_4}^{2-}$, $Cl^-$ and heavy metals in leachate. As a result, the mixed waste with bentonite in all Iysimeters showed the reduction of CODcr and heavy metals were hardly detected. The removal rate of ${NO_3}^-$, ${SO_4}^{2-}$, $Cl^-$ was increased with the mixing rate of bentonite.

• Journal of the Korean Institute of Gas
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• v.8 no.4 s.25
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• pp.50-54
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• 2004

To examine the danger of explosion caused by decomposition explosion of Methyl Ethyl Ketone Peroxide, the mini cup pressure vessel tester (MCPVT) was used in the experiment. The maximum explosion pressure increased as the amount of $98\%H_2SO_4$ added to MEKPO increased from $0\%$ to $1\%,\;3\%$, and $5\%$, and the maximum pressure rising velocity increased as well. In addition, the temperature under the pressure at which decomposition starts decreased from $168.16^{\circ}C$ to $126.76^{\circ}C,\;91.21^{\circ}C$, and $81.25^{\circ}C$ as the amount of $H_2SO_4$ added increased.

• Journal of the Korean Electrochemical Society
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• v.4 no.3
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• pp.118-124
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• 2001

The Langmuir adsorption isotherm of the over-potentially deposited hydrogen (OPD H) for the cathodic $H_2$ evolution reaction (HER) at the $poly-Au|0.5M\;H_2SO_4$ aqueous electrolyte interface has been studied using cyclic voltammetric and ac impedance techniques. The behavior of the phase shift $(0^{\circ}\leq{-\phi}\leq90^{\circ})$ for the optimum intermediate frequency corresponds well to that of the fractional surface coverage $(1\geq{\theta}\geq0)$ at the interface. The phase-shift profile $({-\phi}\;vs.\;E)$ for the optimum intermediate frequency, i.e., the phase-shift method, can be used as a new method to estimate the Langmuir adsorption isotherm $(\theta\;vs.\;E)$ of the OPD H for the cathodic HER at the interface. At the poly-$Au|0.5M\;H_2SO_4$ electrolyte interface, the equilibrium constant (K) and standard free energy $({\Delta}G_{ads})$ of the OPD H are $2.3\times10^{-6}\;and\;32.2\;kJ\;mol^{-1}$, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.2
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• pp.151-155
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• 2007

The issue of acid precipitation and related environmental problems in East Asia have been emerging. To evaluate the acidity and chemical characteristics of rainwater in Korea, its chemical properties during crop cultivation season from April to October were investigated at Suwon, Korea. Also, to estimate the contribution of ions on its acidity, ion composition characteristics and neutralization effects by cation ions were determined. Ion balance and electrical conductivity balance between the measured and estimated values showed high correlation. Rainwater had distributed highly in the range of pH 4.5~5.6. The pH of rainwater was relatively high at June as compared with other monitoring periods. $Na^+$ was the main cation followed by $NH_4{^+}$, $Ca^{2+}$, $H^+$ > $K^+$ > $Mg^{2+}$. Among these, $Na^+$, $NH_4{^+}$, $Ca^{2+}$ and $H^+$ covered over 93% of total cations. About 86% of anion in rainwater was composed of $SO{_4}^{2-}$ and $NO_3{^-}$. In rainwater samples, $NH_4{^+}$ and $Ca^{2+}$ contributed greatly to neutralization of the rain acidity. Also, 88% of soluble sulfate in rainwater was nss-$SO{_4}^{2-}$(non-sea salt sulfate).