• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.111-118
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• 2014

The present study concerns the leachability of alkali ions from hardened cement paste in terms of an increase in the pH together with the rate of alkali leaching. To evaluate the influence of mix design on the leaching capacity and rate of alkali, different water-cement ratios (W/C) and binders were used to manufacture paste specimens. The cement paste was made in the form of rectangular bucket where deionised water was subsequently supplied as solvent media. Then the specimen was wrapped in polythene film to avoid contact to atmospheric conditions, which may affect the water chemistry in the bucket. The pH of media was monitored until no further change in the pH value was observed, of which value then used to calculate the leaching capacity and rate. The influence of binder on the pH of solvent is more dominant than that of water to cement ratio: OPC paste produced the highest level of alkali leaching, whilst 30% PFA and 60% GGBS pastes imposed lower level of alkali leaching. After the monitoring of the pH, the inner bucket was ground with an increment of 1.0 mm to measure the leaching influence using the suspension consisting of paste powder and deionised water. It was found that the impact zone for OPC was about 7-8 mm, whilst 30% PFA and 60% GGBS had deeper impact depth of the alkali leaching.

• Proceedings of the Korean Society of Food and Cookery Science Conference
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• 2003.05a
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• pp.86-86
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• 2003

본 연구는 고추냉이(Wasabia japonica matsum)가 동치미의 발효 중 저장성에 미치는 영향을 알아보고 고추냉이의 최적사용량을 찾아내고자 하였다. 고구냉이는 무 무게에 대하여 0, 3, 5, 7, 9% 첨가하여 동치미를 담그어 1$0^{\circ}C$에서 50일간 발효시키면서 이화학적 특성을 알아보았다. pH의 경우 발효 초기에는 고추냉이 첨가한 처리구가 대조구에 비해 낮게 나타났다. 발효 10일 이후에는 대조구의 pH가 가장 낮게 나타났고 고추냉이 첨가량이 증가할수록 높은 pH를 나타내었다. (중략)

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.05a
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• pp.278-279
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• 2006

본 연구에서는 수중 silica 제거에 이온교환수지의 성능이 실험되었다. 음이온 단일수지에 비해 양이온/음이온 혼합수지가 silica제거에 효과적이었고, 혼합수지에서 온도가 높을수록 교환반응속도는 빨랐다. 음이온과 양이온교환능은 용액의 pH를 변화를 측정하여 해석할 수 있었다. 용액에 공존하는 양이온인 $Na^+$는 혼합수지에서 pH변화에 영향을 주는 물질이었고, 이러한 pH의 변화는 silica의 제거능에 영향을 주었다. 각 온도에서 도달된 평형농도로부터 각 수지에 대한 silica의 선택도계수가 측정되었다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.4
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• pp.620-624
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• 1997

The conditions for color intensity and electron donating ability to $\alpha$,$\alpha$-diphenyl-$\beta$- picryl-hydrazyl (DPPH) of Bacillus subtilis DC-2 were investigated. Temperature, pH and cultivation time were chosen as three factors, and the optimal conditions of color intensity and DPPH was determined with response surface methodology. Color intensity was affected by cultivation temperature(p<0.1). DPPH was influenced by cultivation temperature(p<0.05) and pH(p<0.1). But cultivation time was affected neither color in- tensity nor DPPH. Optimal conditions of color intensity with Bacillus subtilis DC-2 were appeared at cultivation temperature of 39.$25^{\circ}C$, pH 8.83 and cultivation time of 84.41hrs. Optimal conditions of DPPH with Bacillus subtilis DC-2 were revealed at cultivation temperature of 39.19$^{\circ}C$, pH 8.84 and cultivation time of 82.21hrs.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.4
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• pp.297-301
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• 1990

The study was conducted to investigate the effects of diatomearth(pH 3 and CEC 20me/100g) on the adjustment of nursery soil pH and on the growth of rice seedling in the tray. The results are as follows ; 1. The soil pH and damping-off of rice seedling were decreased with increase in diatomearth application. 2. Ten to fifteen percent of diatomearth was required to adjuse the optimum soil pH range of 4.5-5.5. 3. Changes in nursery soil pH adjusted by diatomearth were less than those by sulfuric acid during the incubation period. 4. Diatomearth application increased dry weight and height of rice seedling.

• Journal of Korean Society of Forest Science
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• v.89 no.3
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• pp.422-430
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• 2000

Three-year-old Pinus koraiensis seedlings, transplanted in brown forest soils originating from granite were treated with simulated acid rain of pH concentrations 5.6(control), 4.0, 3.0, 2.5 and 2.0 for 210 days from April 21 to November 17, 1999. Visible injury of the seedlings were observed at the pH 2.0 and pH 2.5 treatments. The total dry weight of the seedlings decreased at pH 2.0 treatment compared with that of the control, and T/R ratio increased at pH 2.0 treatment compared with others. The elements in each part of the seedlings, concentrations of Ca, P and content of chlorophyll in needles increased at the pH 2.0 treatment compared with the control. The concentration of N in the needles of the seedlings increased as the soil pH decreased. As the treated pH was lowered, soil pH has decreased, and concentrations of Ca, Mg, Al, and Mn increased, especially at pH 4.4. In addition, there was a strong correlation(r=0.90, p<0.05 ; r=-0.94, p<0.01) between the dry weight of the seedlings and the pH and Al concentration of the soils. Therefore, the pH and Al concentration in the soil may be useful indicator for assessing the effect of acid rain on the growth of woody plants.

• Journal of the Korean Ceramic Society
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• v.28 no.11
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• pp.885-891
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• 1991

Calcium hydroxyapatite have been synthesized by a direct precipitation reaction between 0.05 M calcium hydroxide suspension and 0.3 M orthophosphoric acid solution. 0.01 M calcium hydroxide solution was added during the reaction in order to increase the total Ca/P mol ration and reaction pH of the solution. The stoichiometric hydroxyapatite was synthesized over 1.75 as total Ca/P mol ratio, but the calcium-deficient hydroxyapatite was prepared under 1.725 as total Ca/P mol ratio. The nonstoichiometry of the precipitates were interpreted in terms of the pH change during the reaction.

• KSBB Journal
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• v.15 no.6
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• pp.664-669
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• 2000

Micellar aggregates are known to be useful for the selective isolation of biologically active materials such as amino acids, proteins, and enzymes from crude mixtures sparsely dispersed in water. In this study, the effects of pH, salt type and its concentration on the solubilization of $\alpha$-chymotrypsin into the organic micellar phase, which consisted of AOT (sodium 야(2-ethylhexy)sulfosuccinate) and iso-octane, were comprehensively examined. It was found that maximum extraction efficiency was attained at a pH below the isoelectric point of $\alpha$-chymotrypsin; at pH=5.0 for NaCl and KCl, and at pH=7.0 for $CaCl_2$and $MgCl_2$. In order to avoid complications stemming from the precipitationof protein at low pH interfaces, the protein concentrations in the organic and aqueous phases were directly measured. The size of the micelle water pool was estimated by measuring the molar ratio of the surfactant to the water, W(sub)o. The resulting values of W(sub)o were nearly constant at 30 and 19 for NaCl and KCl, respectively, and were independent of pH. The addition of 1:2 salts like $MgCl_2$and $CaCl_2$ led to much lower, but a constant value of, W(sub)o than the 1:1 salts.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.3
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• pp.280-285
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• 1983

The effect of pH and calcium on the growth of subterraneum clover (Trifolium subteraneum L.) varieties Dwalganup, Mt. Barker, and Tallarook was determined in solution culture. At pH 4.5 and below all components of growth except germination percentage were adversely affected. The effect of lower pH was improved at high calcium level(3.0mM). There was a varietal difference in response to low pH. Mt. Barker showed the highest percent germination and produced the longest radicle length, whereas the greatest value in top dry weight, root dry weight, root length and number of laterals was obtained with Tallarook.

• Korean Journal of Environmental Agriculture
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• v.15 no.2
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• pp.207-216
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• 1996

Simulated acid rain(SAR) treatment caused a lethal effect on the newly germinated seedlings of Capsicum annum cv. Komyung even though the germination rate of the seeds was stimulated by the treatment of SAR. Young germinated seedlings were much more sensitive to SAR than the already-grown seedlings. The typical symptom caused by SAR was white spot or lesion on the leaf and appeared readily and severely at the low pH of SAR. Generally, Phytophthora rot was severer in SAR treatments than in control. However, the disease was less severe in lower pH of the SAR treatment than in higher pH. Pathogen inoculation following the SAR treatment increased the disease. The severest Phytophthora rot was observed in the SAR treatment of pH 4.0 or 4.5 regardless of the inoculation time.