• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.33.1-33.1
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• 2018

pH is expressed mathematically as $pH=-{\log}[H^+]$, is a measure of the hydrogen ion concentration, [$H^+$] to specify the acidity or basicity of an aqueous solution. The pH scale usually ranges from 0 to 14. Every aqueous solution can be measured to determine its pH value. The pH values below 7.0 express the acidity, above 7.0 are alkalinity and pH 7.0 is a neutral solution. The solution pH can be determined by indicator or by measurement using pH sensor, which measuring the voltage generated between a glass electrode and a reference electrode according to the Nernst Equation. The pH value of solutions depends on the temperature and the activity of contained ions. In nickel electroless plating process, the controlled pH value in some limited ranges are extremely important to achieve optimal deposition rate, phosphorus content as well as solution stability. Basically, nickel electroless plating solution contains of $Ni^{2+}ions$, reducing agent, buffer and complexing agents. The plating processes are normally carried out at $82-92^{\circ}C$. However, the change of its pH values with temperatures does not follow any rule. Thus, the purpose of study is to understand the relationship between pH and temperature of some based solutions and electroless nickel plating solutions. The change of pH with changing temperatures is explained by view of the thermal dynamic and the practical measurements.

• Journal of Pharmaceutical Investigation
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• 제16권2호
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• pp.43-54
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• 1986

To increase the bioavailability of clonixin, clonixin argininate was prepared and compared with clonixin by determining solubility, pKa, lipid-water partition coefficient, dissolution rate and in vivo tests. The results are summerized as followings; 1) The solubility of clonixin argininate was increased by 20 times in water, about 1.2 times in pH 1.2 and pH 8.0 buffer solution, and about 1.8 times in pH 6.8 buffer solution compared with that of clonixin. 2) pKa values of clonixin, clonixin lysinate and clonixin argininate were 6.32, 7.20 and 7.45, respectively. 3) The lipid-water partition coefficient of clonixin argininate was increased more than that of the clonixin in n-hexane, carbon tetrachloride, chloroform, methylene chloride, and n-butanol, but the partition coefficient of clonixin was increased more than that of clonixin argininate in benzene/pH 1.2 buffer solution, ether/pH 8.0 buffer solution, and 3-methylbutyl acetate/pH 1.2, pH 8.0 buffer solution. 4) The time required to dissolve 60% $(T_{60%},\;min.)$ of clonixin argininate was about 1.5 min. in water and pH 1.2 buffer solution, and about 5 min. in pH 6.8 buffer solution. $T_{60%}$ of clonixin lysinate was about 1.5 min. in water, about 1.8 min. in pH 6.8 buffer solution, and about 8 min. in pH 1.2 buffer solution. But $T_{60%}$ of clonixin was about 96 min. in pH 6.8 buffer solution, over 2 hours in water and pH 1.2 buffer solution. 5) Anti-inflammatory effect of clonixin argininate was increased more than that of clonixin over 6 hours, and that of clonixin lysinate was followed by lapse of time. 6) Analgesic effect of clonixin argininate was increased by 1.5 times more than that of clonixin and the effect of clonixin argininate was nearly identical with that of clonixin lysinate. 7) The absorption rates (Ka) of clonixin, clonixin lysinate and clonixin argininate were $0.169\;hr^{-1},\;0.652\;hr^{-1}$ and $0.723\;hr^{-1}$ in situ, respectively.

• 미생물학회지
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• 제19권3호
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• pp.121-127
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• 1981

The constituents of molasses and effect of pH precipitate formation in molasses solution, vary according to its producing districts. The formation of precipitation is not so changeable in the range of buffering zone of molasses solution(pH4.3-6.3) in philippine molasses according to the change of pH value. On lower or higher than the range of buffering zone, the precipitation is increased from pH 4.3 to 2.8 and from 6.3 to 8.1, it is decreased when pH value is lower or higher than the pH value range. For molasses clarifying, it had better adjust the pH of molasses solution to neutral or weak alkali range out of the alkai side of the buffering zone, with lime solution. And then, add the calcium super phosphate solution to pH value of alkali side in buffering zone, as much as the pH of clarified molasses solution can reach to middle value in buffering zone. For the equilibrium of pH value on clarifying molasses, it takes plenty of time more than 6 hours.

• 대한화학회지
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• 제33권2호
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• pp.203-207
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• 1989

지시약 메틸레드 용액을 시료용액에 첨가하고 지시약의 산형의 최대흡수파장과 염기형의 최대 흡수파장 및 등흡광점에서 이 시료액 흡광도를 측정하였다. 이를 측정한 흡광도로부터 이 용액의 pH를 계산하였다. 등흡광점에서 흡광도 범위를 0.1내지 0.3으로 유지하고 시료용액의 pH가 $pK_I{\pm}1$내에서, pH측정오차는 ${\pm}$0.08pH 단위 이내이었다.

• Environmental Engineering Research
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• 제10권4호
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• pp.174-180
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• 2005

Nano-sized iron was synthesized using borohydride reduction of $Fe^{3+}$ in aqueous solution. A wide range of synthesis conditions including varying concentrations of reagents, reagent feeding rate, and solution pH was applied in an aqueous system under anaerobic condition. The reactivity of nano-sized iron from each synthesis was evaluated by reacting the iron with TCE in batch systems. Evidence obtained from this study suggest the reactivity of iron is strongly dependent on the synthesis solution pH. The iron reactivity increased as solution pH decreased. More rapid TCE reduction was observed for iron samples synthesized from higher initial $Fe^{3+}$ concentration, which resulted in lower solution pH during the synthesis reaction. Faster feeding of $BH_4^-$ solution to the $Fe^{3+}$ solution resulted in lower synthesis solution pH and the resultant iron samples gave higher TCE reduction rate. Lowering the pH of the solution after completion of the synthesis reaction significantly increased reactivity of iron. It is presumed that the increase in the reactivity of iron synthesized at lower pH is due to less precipitation of iron (hydr)oxides or less surface passivation of iron.

• 한국가축번식학회지
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• 제15권3호
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• pp.195-199
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• 1991

This study was carried out ot investigate effect of pH stimulation on acrosome reaction of bovine spermatozoa. The results obtained were as follows : 1. When sperm was sequentially washed with SHP solution of pH 7.4, 7.7 and 7.4 and incubated in mTALP solution of pH 7.4 for 120min, 15, 30, 60 and 120min incubations showed significantly(p<0.05) higher sperm acrosome reaction rate than 0 min. 2. When sperm was sequentially washed with SHP solution of pH 7.4, 8.0 and 7.4 and incubated in mTALP solution of pH 7.4 for 15 minutes, sperm acrosome reaction rate was significantly(p<0.01) increased until 9 min. Incubation, but not increased thereafter. 3. When sperm were separately washed with SHP solutions of pH 7.0, 7.4 and 8.0 and incubated in mTALP solution of pH 7.4 for 9min, sperm acrosome reaction rate was 74.8, 71.8 and 93.4%. pH 8.0 showed signifciantly(p<0.01) higher sperm acrosome reaction rate than pH 7.0 and 7.4. The results suggest that stimulation of sperm with high pH induces sperm crosome reaction.

• Restorative Dentistry and Endodontics
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• 제26권4호
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• pp.341-349
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• 2001

Dental caries is the most common oral disease. There are many factors contributing to its development, but complete understanding and prevention are not fully known. However, it is possible to remineralize the early enamel curious lesion by fluoride containing remineralization solution. Recently the pH-cycling model has been used to examine the effect of fluoride solution on remineralization of artificial caries in vitro as it can closely simulate the conditions encountered in vivo within a carefully controlled environment. The aim of this study was to evaluate the remineralizing effects of supersaturated buffer solutions under pH-cycling model. The specimen with 3mm-diameter was made using mature bovine incisors which has no caries and has sound enamel surface. Early curious lesions were produced by suspending each specimens into demineralization solution at pH 5.0 for 33 hours and the specimen whose surface hardness value ranged from 25 to 45 VHN were used. The pH cycling treatment regimen consisted of 5 min soaks of three treatment solutions four times per days for 15 days and the continuous cycling of demineralization and remineralization were carried out for 15 days. Following the pH-cycling treatment regimen, the specimens' surface microhardness were measured by the Vickers hardness test (VHN) and analyzed by ANOVA and Duncan's multiple-range test. 1. The surface microhardness value of supersaturated solution, Senstime, and Gagline groups were increased after pH cycling, and that of supersaturated solution was significantly Increased compared to saline group(P<0.05). 2. The surface remineralization effect of fluoride containing solutions was accelerated by saliva under pH-cycling mode 3. The pH cycling model was considered appropriate to mimic the intra-oral pH changes when evaluating demineralization and remineralization in vitro. Under the results of above study, salivary remineralization effect can be improved by fluoride containing remineralization solution. The pH-cycling model was considered appropriate to mimic the intra-oral pH changes when evaluating demineralization and remineralization in vitro.

• 생물환경조절학회지
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• 제5권2호
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• pp.145-151
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• 1996

수경재배시 변화하는 배양액 pH를 동적으로 조절하기 위한 방법으로 생리적 산, 알칼리와 화학적 산, 알칼리의 효율성을 검토하였다. 배양액 자동조절시스템에 생리적 산, 알칼리로 NH$_4$H$_2$PO$_4$ 및 NaNO$_3$를 이용하고, 화학적 산으로 H$_2$SO$_4$를 이용하여 상추를 재배한 결과, 처리에 관계없이 배양액의 pH를 안정적으로 조절할 수 있었다. 생리적 산, 알칼리의 경우 화학적 산, 알칼리보다 배양액 pH를 급격히 변화시켰으며, 그에 따른 해작용은 나타나지 않았다. 그러므로 상추의 순수수경재배시 배양액의 pH를 자동제어 하기 위한 방법으로, 생육 기간 중에는 화학적 산, 알칼리를 이용하여 pH를 조절하고 수확 며칠 전부터 NH$_4$H$_2$PO$_4$를 화학적 알칼리와 겸해서 공급하는 것이 바람직한 것으로 사료된다.

• 한국결정성장학회지
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• 제8권1호
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• pp.179-186
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• 1998

용액의 초기 pH, 온도, 반응시간 등이 소다 라임 유리용기의 flaking 현상에 미치는 영향에 대해서 연구하였다. 용액중에 flaking 현상을 촉진시키는 $Mg^{2+}$ 이온성분이 존재하지 않는 경우에 $121^{\circ}C$, 초기 pH가 11이상의 조건에서만 flaking 현상이 방생하였으며, 용액의 초기 pH가 9이하인 경우에는 flaking이 발생하지 않았으며 용액의 pH가 10으로 수렴하는 경향을 보였다. flaking 현상은 유리의 표면부분에서 $Ca^{2+}$와 $Na^{2+}$ 이온의 용출에 의해 용출층이 형성되고, 냉각시 모유리와의 열팽창계수 차이로 인해 용출층이 박리되어 나타나며, 알카리의 용출은 초기 pH와 온도에 크게 의존하는 것으로 나타났다. 용액에 $Mg^{2+}$ 이온이 첨가된 경우 규산 마그네슘 수화물 형성에 의해서 용액의 pH가 감소하는 양상을 보였으며, flaking 현상을 촉진시키는 것으로 나타났다.

• 방사성폐기물학회지
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• 제3권4호
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• pp.269-278
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• 2005

본 논문에서는 불필요한 용액의 발생이 없이 전해 반응계로 주입되는 용액을 오직 pH 만 조절시켜 배출시키기 위한 연속식 이온교환막 전해 시스템을 개발하였다. 여기서는 전해 반응기 앞에 한 pH-조정조를 두고 대상 용액을 pH-조정조로 주입하면서 pH-조정조의 용액의 일부를 이온 교환막에 따라 음극방 또는 양극방으로 거처 다시 pH-조정조로 순환하게 하며, pH-조정조의 용액의 일부를 상대극 방으로 통과시킴으로써 pH가 조절되어 배출되게 하였다. 양이온 교환막을 사용하는 경우 음극방을 거치는 용액을 pH-조정조로 순환하게 하고, 음이온 교환막을 사용하는 경우 양극방을 거치는 용액을 pH-조정조로 순환하게 함으로서 배출되는 용액을 효과적으로 산성용액 또는 알카리용액으로 만들 수 있었다. 이러한 전해반응기에서 pH 조절 과정은 음극과 양극 사이에 전압 차가 형성될 시, 이온교환막을 통한 용액 중 이온의 전기이동 현상에 의해 유발되는 음극방과 양극방에서 용액의 전하 비 평형 현상과 이에 따른 물의 전해 분해과정에 의해 설명되었다.