• The Korean Journal of Ecology
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• v.17 no.1
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• pp.69-78
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• 1994

The acidic deposition (wet) was collected at three different locations; representative industrial (Kun-Jang industrial areas), semiindustrial (Kunsan City) and nonindustrial (Daeya areas) region between March, 1991 and June, 1993. Samples were analyzed for major chemical components along with pH. Also the responses of Hypnum filunzaeforme to the acidic deposition adjusted to pH 4.6, 3.6 and 2.6 with 1:4 molar ratio of nitric to sulfuric acid were investigated. Seasonal variation of pH showed the lowest in early spring and the highest in summer. The annual mean concentrations of $S0_4^{2-},\;NO_3^{-}\;and\;NH_4^{+}$ were 2.94 (81.0%), 0.48 (13.2%) and 0.21 (5.78%) mg/l in industrial region and 0.61 (64.21%), 0.25 (26.3%) and 0.9 (9.5%) mg /I in nonindustrial region, respectively. $S0_4^{2-}$ contents of industrial region was 4 times higher than those of nonindustrial region. The ratio of $S0_4^{2-}\;to\;NO_3^{-}$ was 4.75~7.35 in industrial region and 0.69-6.36 in nonindustrial region. The acidic deposition near industrial region was associated with excess ions, expecially $S0_4^{2-}$. Nitrate reductase activity(NRA) of mosses was inhibited by acidic deposition in both regions. The time required for the maximum NRA induction by 2mM $KNO_3$ was shortened in mosses collected from industrial region. Photosynthesis of H. plumaejorme began to decrease with acidic deposition by pH below 4.6, and was completely inhibited at pH 2.6 in both regions. Water potential of mosses treated with acidic deposition was almost constant during 18 days, however after withholding the supply of acidic deposition, it was rapidly decreased.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.4
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• pp.43-48
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• 2011

Electroless nickel platings on carbon substrate were investigated for porous MCFC electrode applications. Acidic bath and alkaline bath were used in electroless nickel plating on carbon substrates. The rate of electroless plating in alkaline bath was faster than that in acidic bath. As pH was increased, the deposition rate was increased in both baths and the content of phosphorus in nickel deposit was decreased. The residual stresses of nickel deposit from acidic bath showed the compressive stress and on the other hand those from alkaline bath showed the high tensile stress. High tensile internal stress in nickel deposit caused the cracks over pH 11. Thiourea was added to both acidic and alkaline bath. The deposition rate of nickel was increased upto 0.5 ppm of thiourea and decreased. The maximum concentration of thiourea for the electroless nickel plating on carbon substrate was 1.5 ppm in both acidic and alkaline bath. Succinic acid was added to acidic bath. Addition of succinic acid up to 5 g/L increased the deposition rate of nickel and beyond which the deposition rate was decreased and maintained.

• The Korean Journal of Ecology
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• v.28 no.6
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• pp.417-431
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• 2005

Soils of Korea experienced with long-term acidic deposition have been exhaustively leached exchangeable base cation (BC) for plant nutrient comparable with soils of forest decline areas in Europe and N. America. Ratios of $BC/Al^{3+}$ of most soils are below than 1, which value is critical load for plant growth. Acid soil applied with dolomitic liming is increased as much as 20% and 244% in concentrations of $Ca^{2+}$ and $Mg^{2+}$, respectively, as well as shrub leaves increase much cation uptake by 1 year later. Ions of $NO_3^-$ and $NH_4^+$ in acid rain are absorbed by the canopy acted as the sink but f is leached out from the canopy to throughfall as the source at Gwangneung forest with a little of acidic deposition, however, such sink and source functions are not found at Kwanaksan forest because of so much deposition. In coniferous and deciduous forested watershed ecosystems ions of $K^+$, $Cl^-$, $NO_3^-$ and $SO_4^{2-}$ from throughfall are retained in forest floor but ions of $Na^+, $Mg^{2+}$ and $Ca^{2+}$ are leached from the floor to streamwater.

• The Korean Journal of Ecology
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• v.15 no.4
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• pp.355-363
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• 1992

Nitrate reductase activity(NRA) and induced NRA were compared in 4 species of moss ctenidium molluscum, homalothecium, tortella tortusa and neckera crispa collected from limestone in england. the NRA and dry weight of the c. molluscum were also measured after spraying with acidic deposition adjusted to ph 5.6, 4.6, 3.6 and 2.8 with one of two molar ratios of nitric to sulfuric acid, i.e. 1:0(N alone) and 1:2(1N+2S) for 20 days. All 4 species showed high NR leavels in the upper part of cut shoots and occurred maximum inducation of NRA within 6h. c. molluscum had the highest NRA levels among 4 species. after daily spraying of acidic deposition, NRA of c. molluscum was increased much more largely at ph 6 and ph 3.6 derived from N alone than from 1N+2S. However that was decreased at ph 2.8 derived both from N alone and 1N+2S . Decline of dry weight had occurred at ph 3.6 and 2.8 derived both from N alone and 1N+2S. Whereas substantial fertilization effect was observed at ph 4.6 derived from N alone. the data suggest that c. molluscum are able to utilize nitrate more effectivery than any other species, and NRA induction are more sensitive than growth response to nitrogen content of acidicdeposition in a short- term. however toxic effects was detected at high $NO_3$ supply and low phacidic deposition.

• Proceedings of the Microbiological Society of Korea Conference
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• 2002.10a
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• pp.100-105
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• 2002

The diversity of epiphytic bacterial communities on deciduous oak tree (Quercus dentate Thunb.) leaves was examined both in the natural forest area with a clean air and in the industrial estate to assess effects of acidic deposition to the phyllosphere using 16S rDNA sequence data. In addition, acid-tolerant epiphytic bacterial communities were compared. A total of 78 epiphytic and 444 acid-tolerant clones were obtained from clone libraries, resulting in 20 and 17 phylotypes by analysis of restriction fragment length polymorphism (RFLP) for PCR-amplified 16S rDNA products. A low bacterial diversity in both areas was found. As tree leaves grow older, bacterial diversities were slightly increased in the level of subphylum. The community structure of epiphytic bacteria in both areas in April consisted of only two subphyla, $\beta-and\;\gamma-Proteobacteria$. In August two additional subphyla in both areas were found, but the composition was a little different, Acidobacteria and Cytophaga-Flexibacter-Bacteroids (CFB) group in the industrial estate and a -Proteobacteria and CFB group in the natural area, respectively. Acidobacteria could be an indicator of epiphytic bacteria for acidic deposition on plant leaves, whereas a -Proteobacteria be one of epiphytic bacteria that naturally survive on leaves that are not affected by acidic deposition. The acid-tolerant bacterial communities in April were composed of two subphyla, $\gamma-Proteobacteria$ and Low G+C gram-positive bacteria in both areas, and in August a-Proteobacteria was added to the community just in the natural forest area. The direct influence of acidic deposition on the acid-tolerant bacterial phylogenetic composition could not be detected in higher taxonomic levels such as subphylum, but at narrower or finer levels it could be observed by a detection of Xanthomonadales group of $\gamma-Proteobacteria$ just in the industrial estate.

• Journal of the Korean institute of surface engineering
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• v.43 no.2
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• pp.105-110
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• 2010

Electroless nickel plating on porous carbon substrate for the application of MCFC electrodes was investigated. Acidic and alkaline bath were used for the electroless nickel plating. The pore sizes of carbon substrates were 16-20 ${\mu}m$ and over 20 ${\mu}m$. The carbon surface was changed from hydrophobic to hydrophilic after immersing the substrate in an ammonia solution for 40 min at $60^{\circ}C$. The contact angle of water was decreased from $85^{\circ}C$ to less than $20^{\circ}$ after ammonia pretreatment. The deposition rate in the alkaline bath was higher than that in the acidic bath. The deposition rate was increased with increasing pH in both acidic and alkaline bath. The content of phosphorous in nickel deposit was decreased with increasing pH in both acidic and alkaline bath. The contents of phosphorous is low in alkaline bath. The minimum concentration of $PdCl_2$ for the electroless nickel plating was 10 ppm in alkaline bath and 5 ppm in acidic bath. The thickness of nickel was not affected by the concentration of $PdCl_2$.

• The Korean Journal of Ecology
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• v.28 no.3
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• pp.169-180
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• 2005

Nitrogen dioxide concentration was being grown ca. 8% per year although sulphur dioxide concentration was being reduced ca. 10% per year in Seoul from 1996 to 2003. The rainwater was heavily acidic with pH 4.19 to 4.68 in Seoul during 1980 to 1991. Acidity score on the basis of the total anion concentration of rainwater follows the higher in sequence with Seoul(Kwanaksan)(341.5 ${\mu}equiv{\cdot}L^{-1}$), Gwangneung(199.2 ${\mu}equiv{\cdot}L^{-1}$) and whole Korea mean(10.3 ${\mu}equiv{\cdot}L^{-1}$). Rainwaters from 38 sampling sites of 16 countries in the world, on the basis of the acidity score, are classified and designated as five acid rain grades(ARG): the least score is founded in Tana Rata(16.2 ${\mu}equiv{\cdot}L^{-1}$), Malaysia where has the best rain but the greatest founded in Chongquing(541.1 ${\mu}equiv{\cdot}L^{-1}$), China where has the worst rain in the world. Even though acidic deposition decrease with time in the world generally, it is expected to increase in Asia, Africa and Mid-South America.

• Korean Journal of Environment and Ecology
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• v.15 no.3
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• pp.230-236
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• 2001

The fluxes of wet deposition(WD), throughfall(TF), stemflow(SF) and soil leachates were measured to understand base cation budgets on deciduous ecosystem impacted by acidic deposition in the north-western part of Tomakomai in Hokkaido, Japan. The flux of $H^{+}$ for wet deposition was $0.34kmo1_{c}$ $ha^{2+}$ and the flux of base cation, $K^{+}$ /, Na$^{ + }$, $Ca^{2+}$ and $Mg^{2+}$ far throughfall plus stemflow wart 1.6 kmolc $ha^{-1}$ , 3 times higher level than that for wet deposition. The flux of base cation for canopy leaching(LI) was 0.95 kmolc ha$^{-1}$ , 2.8 times higher level than $H^{+}$ sources in wet deposition. The major mechanism of $^{+}$ consumption closely related to acidic neutralizing capacity of canopy. The ionic flux for soil leachates from Boil reservoir and proton consumption in soil was dependent on soil chemical states and exchangeable Ca in soil had a major factor of H$^{+ }$ consumption. The base cation budgets on deciduous ecosystem showed positive balance fur Na, Ca and Mg, while K was the negative value.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.3
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• pp.421-426
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• 2004

Dry deposition fluxes of inorganic acidic species to the waterbody were measured by the dry deposition sampler (DDS). DDS was composed of three pans filled with pure water. An average concentration increase during the sampling time, after removing an abnormal value if existed, was considered as the input by deposition. Important operation parameters such as the amount of water used and sampling time were determined through a series of laboratory experiments. The deposition flux measured by DDS was compared with that by the water surface sampler developed by Yi et ai. (1997a,b).

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.323-323
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• 2010

Saw damage of crystalline silicon wafer is unavoidable factor. Usually, alkali treatment for removing the damage has been carried out as the saw damage removal (SDR) process for priming the alkali texture. It usually takes lots of time and energy to remove the sawed damages for solar grade crystalline silicon wafers We implemented two different mixed acidic solution treatments to obtain the improved surface structure of silicon wafer without much sacrifice of the silicon wafer thickness. At the first step, the silicon wafer was dipped into the mixed acidic solution of $HF:HNO_3$=1:2 ration for polished surface and at the second step, it was dipped into the diluted mixed acidic solution of $HF:HNO_3:H_2O$=7:3:10 ratio for porous structure. This double treatment to the silicon wafer brought lower reflectance (25% to 6%) and longer carrier lifetime ($0.15\;{\mu}s$ to $0.39\;{\mu}s$) comparing to the bare poly-crystalline silicon wafer. With optimizing the concentration ratio and the dilution ratio, we can not only effectively substitute the time consuming process of SDR to some extent but also skip plasma enhanced chemical vapor deposition (PECVD) process. Moreover, to conduct alkali texture for pyramidal structure on silicon wafer surface, we can use only nitric acid rich solution of the mixed acidic solution treatment instead of implementing SDR.