• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.382-386
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• 1998

The objectives of this study are to reveal relationship between tree physiology and spectral reflectance on effects of artificial acid rain and to obtain basic data on optimal wave length for forest of LRC sensor on KOMPSAT-2. Three pH levels of artificial acid rain - control, pH4.5 and pH3.0 - were applied to Pinus and Quercus species. Three types of the acid rain were spraied at the amount of 500m1 in every two days. Spectral reflectance data was collected once in a month by using GER 1500 (350~2500nm) or Ll 1800(300~1100nm) Spectroradiometer. The data was measured three times in a pH level. The results of this study are as follows; in April, the spectral reflectance of Pinus species was high in order at the level of pH3.0, control and pH4.5; in May, control, pH3.0 and pH4.5; in June, control, pH4.5 and pH3.0. That of Quercus species was high in the order of control, pH4.5 and pH3.0 in May; in June, control, pH3.0 and pH4.5, especially, within infrared wave length range, control, pH4.5 and ph3.0.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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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.

• KSBB Journal
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• v.14 no.1
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• pp.58-65
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• 1999

A hydrogel, poly(N-isopropylacrylamide-co-N,N'-dimethylaminopropyl methacrylamide), sensitive to both pH and temperature was synthesized and characterized for its welling behavior, lower critical solution temperature (LCST), and its appearance. The hydrogel with 5 mol% of N,N'-diemthylaminopropyl methacrylamide (DMAPMAAm) increased its volume phenomenonally in a lower pH range (ph 1~8) even at temperature ($37^{\circ}C$ and $40^{\circ}C$) higher than LCST. This behavior was unique compared to the temperature -sensitive hydrogel which did not exhibit any swelling in the same pH range. The hydrogel with 20 mol% of DMAPMAAm was swollen significantly at a higher pH of 12. With pH decrease from 12 to 2 water content in the gel increased from 38.8 wt% and 60.6 wt%, and 90.8 wt% for 5 mol% and 20 mol% gel, respectively. The transition pH that pH effect overwhelmed temperature effect occurred at a lower pH for a higher temperature ($40^{\circ}C$) and a lower mol% (5 mol%) of DMAPMAAm. Transparency and LCST of the gel increased with higher DMAPMAAm mol%.

• Journal of Sensor Science and Technology
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• v.5 no.2
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• pp.15-20
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• 1996

The diffusion of hydrogen ions into a sensing membrane causes the output voltage of pH-ISFET to vary with time, which might be considered to be drift in this sensor. We tried to deposit ultra-thin film for minimizing tile drift that has been considered to be main obstacle for putting pH-ISFET to practical use. In this paper, tantalum pentoxide, known as a good pH sensing membrane, was formed to about $70{\AA}$ thick by sol-gel method on $Si_{3}N_{4}/SiO_{2}$-gate of pH-ISFET. The fabricated $Ta_{2}O_{5}$-gate pH-ISFET showed good sensitivity(about 59mV/ pH) and good lineality in the range of pH $3{\sim}11$, and had relatively small average pH drift of about 0.06 pH/day.

• Journal of the Korean Chemical Society
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• v.64 no.2
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• pp.74-78
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• 2020

A push-pull conjugated dye (DCMP) was covalently immobilized on a silanized glass surface to produce a high sensitivity pH sensor film for operating in the acidic region. A pH-sensitive sensor film was prepared by photo-initiating copolymerization of a modified DCMP (DCMA), 2-hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate on the silanized glass surface. The absorbance of the sensor film increased with increasing pH between pH 2.0 and 5.0, and the fluorescence intensity of the film also increased about 50 times with increasing pH in the same pH range. The sensor film was reversible and reproducible under acidic conditions. The sensor film showed a relatively short response time between 20-50 seconds and high selectivity for proton in the presence of various metal ions.

• Journal of the Korean Geotechnical Society
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• v.23 no.8
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• pp.97-106
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• 2007

In this study, experiments are conducted to find out the effect of waste leachate on landfill clay liner system. Tensile test, hydrometer analysis and crack pattern test were conducted on sand-bentonite mixtures with different pH values of water. The tensile strength of specimen compacted with pH 9 of water is smaller than that of specimen compacted with for pH 3 and 6 of water. That is, the higher the pH value, the smaller the tensile strength, because a higher pH solution decreases flocculation phenomenon. The percent finer also increased with high pH value in particle size distribution of fine grained soil (<0.075 mm), because the velocity of particles settling decreases. This trend becomes the clearer as the content of bentonite, becomes the larger, because the higher pH value decreases flocculation structure of fine soils. The results of the crack pattern tests also showed the effect of pH values of water.

• Polymer(Korea)
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• v.37 no.3
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• pp.262-268
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• 2013

pH-sensitive P(MAA-co-PEGMA) hydrogel particles were prepared and their feasibility as smart delivery carriers for cosmetic ingredients was evaluated. P(MAA-co-PEGMA) hydrogel particles having an average size of approx. $2{\mu}m$ were synthesized via dispersion photopolymerization. There was a drastic change in the swelling ratio of P(MAA-co-PEGMA) particles at a pH of around 5 due to the ionization of MAA in the hydrogel and as the amount of MAA in the hydrogel increased, the swelling ratio increased at a pH above 5. The P(MAA-co-PEGMA) hydrogel particles showed a pH-sensitive release behavior. Thus, at pH 4 almost none of the albumin permeated through the skin while at pH 6 relatively high skin permeability was obtained. The albumin loaded in the P(MAA-co-PEGMA) hydrogel particles was hardly degraded in the presence of pepsin and its stability was maintained.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.739-742
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• 2003

Curdlan acetate was prepared from hydrophilic curdlan by chemical modification and it was used for pH-sensitive drug delivery system. Curdlan acetate microspheres were prepared by the solvent evaporation method. The size of the curdlan acetate microspheres was below $200\;{\mu}m$. The drug loading efficiency of microspheres was approximately 58.44%. In the swelling test, curdlan acetate microspheres were showed pH-sensitive behavior. The swelling capacity of microspheres at pH 7.4 was much greater than at pH 1.4. Also, Release rate of indomethacin (IND) at pH 7.4 from curdlan acetate microspheres was faster than that at pH 1.4. A pH-sensitive drug release pattern was due to the disintegrating after swelling.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.571-574
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• 2000

Hydrolase is a group of the most widely used enzymes in industrial biological processes. Generally, their activities are easily changed with pH. With this characteristics, research for the optimal pH of hydrolases is required to obtain the optimization of process conditions. We selected xylanase, lysozyme, glucoamylase and barnase as model enzymes. To predict optimum pH of hydrolases, the calculation program based on Tanford-Kirkwood(TK) model was used. Results show that charge difference of catalytic residues is an important parameter deciding optimum pH and when charge difference of catalytic residues is maximum, optimum pH of the hydrolase establishes.

• Journal of the Korean institute of surface engineering
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• v.35 no.2
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• pp.93-100
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• 2002

To better understand the codeposition mechanism of phosphorous, surface pH and potential of cathode were measured during electrodeposition of Ni-P alloys. The pH of cathode surface was measured using a flat-bottom glass pH electrode and a 500 mesh gold gauze as cathode. The cathode surface pH was increased with increasing the current density and always higher than the pH in the bulk solution. As a result of overplotting the surface pH and cathode potential on the Pourbaix diagram, it was found that cathode surface shift to the domain of predominant of $H_2$$PO3$-or $H_2$$PO_2$-. Additionally, new deposition mechanism was suggested that $H_2$ $PO_2$- and $H_2$$PO_3$- play important roles in the deposition reaction of Ni-P alloys.