• The korean journal of orthodontics
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• v.40 no.2
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• pp.95-105
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• 2010

Objective: To identify clinical, salivary, and bacterial changes during orthodontic treatment with follow-up to 24 months. Methods: In 30 patients, clinical (decayed, missing, and filled surfaces [DMFS], O'Leary's plaque index, and plaque pH), salivary (unstimulated and stimulated saliva, buffer capacity, pH, and occult blood), and bacterial (Streptococcus mutans and Lactobacillus) markers were evaluated. A questionnaire was employed to evaluate their hygienic-dietary habits. Data were analyzed by ANOVA, logistic regression and Spearman's correlation. Results: DMFS increased significantly, whereas the plaque index diminished, plaque pH was more acidic (p = 0.23), and unstimulated salivary flow showed significant differences during the treatment (p = 0.013). Stimulated saliva flow increased in females after the placement of appliances; buffer capacity was diminished in males during the therapy; salivary pH remained at basal values. Bacterial levels and occult blood increased to high-risk levels and were not statistically significant different between genders (p > 0.05). Two major relationships were confirmed: initial plaque with use of dental aids (r = 0.429; p = 0.018) and final DMFS with unstimulated salivary flow (r = -0.372; p = 0.043). Conclusions: The increase in retentive surfaces increased the bacterial levels, plaque pH became acidified, and gingival damage was greater. Buffer capacity was altered but maintained a healthy salivary pH during the treatment.

• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.699-710
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• 2006

Batch scale experiments to investigate the efficiency of the solidification process for metal mine tailing treatment were performed. Portland and MSG (micro silica pouting) cements were used as solidifier and three kinds of mine tailings (located at Gishi, Daeryang, and Aujeon mine) were mixed with cements to paste solidified matrices. Single axis com-pressible strengths of solidified matrices were measured and their heavy metal extraction ratios were calculated to investigate the solidification efficiency of solidified matrices created in experiments. Solidified matrices ($5cm{\times}5cm{\times}5cm$) were molded from the paste of tailing and cements at various conditions such as different tailing/cement ratio, cement/water ratio, and different cement or tailing types. Compressible strengths of solidified matrices after 7, 14, and 28 day cementation were measured and their strengths ranged from 1 to $2kgf/mm^2$, which were higher than Korean limit of compressible strength for the inside wall of the isolated landfill facility ($0.21kgf/mm^2$). Heavy metal extractions from intact tailings and powdered matrices by using the weak acidic solution were performed. As concentration of extraction solution for the powdered solidified matrix (Portland cement + Gishi tailing at 1:1 w.t. ratio) decreased down to 9.7 mg/L, which was one fifth of As extraction concentration for intact Gishi tailings. Pb extraction concentration of the solidified matrix also decreased to lower than one fourth of intact tailing extraction concentration. Heavy metal extraction batch experiments by using various pH conditions of solution were also performed to investigate the solidification efficiency reducing heavy metal extraction rate from the solidified matrix. With pH 1 and 13 of solution, Zn and Pb concentration of solution were over the groundwater tolerance limit, but at pH $1{\sim}13$ of solution, heavy metal concentrations dramatically decreased and were lower than the groundwater tolerance limit. While the solidified matrix was immerged Into very acidic or basic solution (pH 1 and 13), pH of solution changed to $9{\sim}10$ because of the buffering effect of the matrix. It was suggested that the continuous extraction of heavy metals from the solidified matrix is limited even in the extremely high or low pH of contact water. Results of experiments suggested that the solidification process by using Portland and MSG cements has a great possibility to treat heavy metal contaminated mine tailing.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1071-1079
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• 2011

In this study, coal combustion ash (CCA) was evaluated for its stabilization effect on acidic mine waste with column experiment. Total of six treatments were installed depending on mixing ratio between coal wastes and CCA (0, 20, 40%) and mixing method (completely mixing and layered). Artificial acidic rain (pH 5.6) was used for feeding solution with flow rate of $0.05mL\;min^{-1}$. Result showed that higher pH of leachate was observed as more CCA was mixed. The highest pH in leachate was measured when 40% of CCA was mixed with coal waste (pH of 5.8). Also, complete mixing with CCA and coal waste was more effective to increase the pH of leachate than layered treatment. Regarding the reduction of soluble Fe amount, the highest efficiency (78%) was observed when 20% of coal ash was completely mixed with mine waste. Based on those result, optimum mixing ratio of coal ash with mine waste can be ranged 20-40% depending on environmental circumstances in the field.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.733-737
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• 2012

The objectives of this study were to investigate soil chemical properties for forest rehabilitation and suggest design and management in abandoned coal mine areas in Mungyeong, Gyeongsangbuk-do. Total study sites were 10 sites, and soil analysis particular were soil pH, TOC, total-N, C/N ratio, A.v. $P_2O_5$, and CEC. Because most of study sites showed soil pH from 5.0 to 7.0, it seems that soil pH does not affect growth of vegetation. But soil pH in Danbong1 was acidic (pH 4.6), so it is needed to improve with ameliorant such as limestone. Most of study sites is necessary to manage for organic matter and Nitrogen, because there sites showed lower value of TOC and total-N than general forest. The values of A.v. $P_2O_5$ and CEC were good in most of study sites, so it seems that they do not have effect on vegetation growth. All of soil factors has no regression according to elapsed time after rehabilitation. TOC, total-N and A.v. $P_2O_5$ among soil properties have positive relationship between each other. It is necessary to fertilizer for organic matter and Nitroge because of value in TOC, total-N and C/N ratio. The results of this study were analyzed only one time. So, long-term monitoring for soil properties is important for the correct forest rehabilitation and management.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.15-18
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• 2001

Sixty natural springs and wells used as community facilities for drinking water are developed along mountain climbing way of suburban area and residential area in Daejeon City. In this study, the seasonal variation of their water quality and hydrochemical characteristics were investigated. Some natural springs are vulnerable to bacilli contamination because of their short residence time and shallow circulation in subsurface environment. The waters show hydrochemical types of Ca-HCO$_3$ and Na-HCO$_3$, and are characterized by low electrical conductance and weak acidic pH.

• Mycobiology
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• v.37 no.4
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• pp.286-294
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• 2009

Heteropolysaccharides isolated from liquid cultures of nine Tremella species contained 0.3 to 1.2% protein, 2.7 to 5% ash, 0.9 to 3.4% acetyl groups, 76.5 to 84.2% carbohydrates and trace amounts of starch. The polysaccharides in aqueous solution were slightly acidic (pH 5.1 to 5.6). They consisted of the following monomeric sugars: fucose, ribose, xylose, arabinose, mannose, galactose, glucose and glucuronic acid. The backbones of the polysaccharide structures consisted of $\alpha$-(1$\rightarrow$3)-links while the side chains were $\beta$-linked.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.328.1-328.1
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• 2002

A major lipid-signaling pathway in mammalian cells implicated the activation of sphingomyelinase (SMase), which hydrolyses sphingomyeline to generate ceramide and phosphocholine. Sphingomyelinase is divided into many isoform groups dependent on optimal pH, and essential cation especially magnesium in their activation. Such as acidic sphingomyelinase, neutral sphingomyelinase and alkaline sphingomyelinase. Ceramide is known as a crucial second messenger in cell responses like cell proliferation. cell cycle arrest. cellular senescence, and apoptosis. (omitted)

• Journal of the Korean Chemical Society
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• v.42 no.2
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• pp.172-176
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• 1998

An anion exchange resin which has Alizarin Red S (ARS) as functional group was prepared by batch method. The resin is stable in acidic solutions below 0.5 M hydrochloric acid, nitric acid and sulfuric acid and adsorption capacity of Fe(Ⅱ) ion on the resin was larger than other metal ions. The preconcentration and the separation of Fe(Ⅱ) ion from the mixture solution were carried out with the pH 4.5 buffer solution and 0.1 M $HNO_{3}$ as eluents.

• Korea-Australia Rheology Journal
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• v.20 no.2
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• pp.65-71
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• 2008

Pressure filtration technique was used to obtain defect-free microstructure of green cast ceramic bodies. Stable alumina suspensions of desired rheology (<5 Pa s at $1\;s^{-1}$) containing 60-80 mass. % solid loading were prepared in the alkaline region (at $pH{\approx}9$) with an optimum amount of 0.5 dmb % of Tiron added. Acidic region (at $pH{\approx}4$) enabled the preparation of 60 mass. % suspensions with addition of 1.5 dmb % of Tiron. The best quality slip was processed from an 80 mass.% suspension with 63% of theoretical density. The homogeneity of particle packing and the absence of defects in microstructure were proven by narrow pore size distribution (ranging from 32 to 64 nm, with up to 85% abundance), confirming advantages of the wet consolidation route.

• The Plant Pathology Journal
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• v.26 no.2
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• pp.198-202
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• 2010

A study was conducted to find out the relationship of physico-chemical properties (viz. organic carbon(OC), pH, electrical conductivity, nitrogen, phosphorus and potassium content) of ginger growing soil with incidence percentage of rhizome rot and wilt disease complex of ginger. Organic carbon content and pH of the ginger soil contributed significantly (93%) in the prediction of ginger rhizome rot and wilt disease complex incidence with negative correlation. Soil having weak acidic reaction with OC percent greater than 2.25 was observed to have the lower average incidence of the disease.