• Journal of Sensor Science and Technology
• /
• v.26 no.6
• /
• pp.414-419
• /
• 2017

The optical characteristics of cresol red, phenol red, and neutral red immobilized in the thin film were investigated with absorbance measurement in order to find a sensing part of a fiber-optic pH sensor. Sol-Gel method with tetramethyl orthosilicate as a precursor was used to immobilize the pH indicators in the thin film. The absorbance spectra were measured when pH indicators were immobilized in the film and were dissolved in the buffer solution. Experimental results showed that the absorbance spectra could be changed when the pH indicator is immobilized in the thin film. As compared with other pH indicators, the neutral red exhibited similar absorbance spectra regardless of physical conditions and was sensitive over whole pH range between 4 and 11. In addition, the absorbance ratio of base peak to acid peak tended to increase in proportion to the increase in pH. Experimental results indicate that the neutral red is a good pH indicator for fabrication of a sensing part of the fiber-optic pH sensor.

• Corrosion Science and Technology
• /
• v.4 no.4
• /
• pp.121-129
• /
• 2005

Basic design concept of the future steel structure requires environmental compatibility and maintenance free capability to minimize economic burdens. Recent trends in alloy design for advanced weathering steel include addition of various alloying elements which can enhance formation of stable and protective rust layer even in polluted urban and/or high $Cl^{-}$ environment. The effects of Ca, Ni, W, and Mo addition on the corrosion property of Ca-modified weathering steel were evaluated through a series of electrochemical tests (pH measurement and electrochemical impedance spectroscopy: EIS) and structural analysis on rust layer formed on the steel surface. Ca-containing inclusions of Ca-Al-Mn-O-S compound are formed if the amount of Ca addition is over 25 ppm. Steels with higher Ca content results in higher pH value for condensed water film formed on the steel surface, however, addition of Ni, W, and Mo does not affect pH value of the thin water film. The steels containing a high amount of Ca, Ni, W and Mo showed a dense and compact rust layer with enhanced amount of ${\alpha}-FeOOH$. Addition of Ni, W and Mo in Ca-modified weathering steel shows anion-selectivity and contributes to lower the permeability of $Cl^{-}$ ions. Effect of each alloying element on the formation of protective rust layer will be discussed in detail with respect to corrosion resistance.

• Journal of Environmental Health Sciences
• /
• v.13 no.1
• /
• pp.35-40
• /
• 1987

Personal computer based measurement and control system was constructed and tested in order to fiexibly apply it to laboratoy experiments in which environmental factors such as temperature, humidity, pH, DO and gases should be measured and controlled. Personal computer FC-80 was successively interfaced to the input-output system made up of PPI, A/D converter, D/A converter, programmable timer and USART boards. To test the system, pH control experiment was executed and the pH of the solution could be measured, expressed on the monitor and controlled at constant value.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2007.06a
• /
• pp.661-662
• /
• 2007

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.5
• /
• pp.1730-1734
• /
• 2010

Generally, a pH value of secondary water in a nuclear power plant should be estimated after sampling and cooling down. In this process, the measurement of temperature is very important because a pH value is varied according to the temperature of secondary water. In this study, a noncontact fiber-optic temperature sensor using a silver halide optical fiber is fabricated to measure the temperature of cooled secondary water. And we have measured an infrared radiation, which is transferred by a silver halide optical fiber from a heat source, using a thermopile sensor. The relationships between the temperature of a heat source and the output voltage of the fiber-optic temperature sensor according to the change of distance and angle are determined. The measurable temperature range of the fiber-optic temperature sensor is from 25 to $60^{\circ}C$. Based on the results of this study, a noncontact temperature sensor using a silver halide optical fiber can be developed for the temperature measurement of the pH sample in the secondary water system.

• Journal of Soil and Groundwater Environment
• /
• v.29 no.1
• /
• pp.1-9
• /
• 2024

As part of monitoring technology aimed at verifying the stability of CO₂ geologic storage and mitigating concerns about leakage, a method for measuring the pH and alkalinity of high-pressure fluid samples was established to obtain practical technology. pH measurement for high-pressure samples utilized a high-pressure pH electrode, and alkalinity was measured using the Gran titration method for samples collected with a piston cylinder sampler (PCS). Experimental samples, referencing CO₂-rich water and CO₂ geologic storage studies, were prepared in the laboratory. The PCS controls the piston, preventing CO₂ degassing and maintaining fluid pressure, allowing mixing with KOH to fix dissolved CO₂. Results showed a 6.1% average error in high-pressure pH measurement. PCS use for sample collection maintained pressure, preventing CO₂ degassing. However, PCS-collected sample alkalinity measurements had larger errors than non-PCS measurements, limiting PCS practicality in monitoring field settings. Nevertheless, PCS could find utility in preprocessing for carbon isotope analysis and other applications. This research not only contributes to the field of CCS monitoring but also suggests potential applications in studies related to natural analogs of CCS, CO₂-rock interaction experiments, core flooding experiments, and beyond.

• Applied Chemistry for Engineering
• /
• v.32 no.6
• /
• pp.700-705
• /
• 2021

A portable and disposable pH sensor based on Ti wire was successfully developed for monitoring hydronium ion concentrations. A sensing electrode was prepared by electrochemically depositing iridium oxide onto a Ti wire, while a reference electrode was fabricated by coating Ag/AgCl ink on a Ti wire. Combining the two electrodes in the pH sensor enabled the collection of open circuit potential signals when the sensor was immersed in solutions of various pH values. The pH sensor exhibited excellent electrochemical sensing performance in terms of sensitivity, response time, repeatability, selectivity, and stability. To demonstrate point-of-measurement applications, the pH sensor was integrated with a wireless electronic module that could communicate with a mobile application. The portable pH sensor accurately measured pH changes in real samples. The results obtained were consistent with those of using a commercial pH meter.

• YAKHAK HOEJI
• /
• v.29 no.4
• /
• pp.220-222
• /
• 1985

Rifampicin reacts with cupric ion to produce rifampicin-Cu(II) chelate (2:1) at pH 6.5, which can be extracted with methylisobutylketone (MIBK). Therefore, rifampicin can be quantitatively, determined by measuring the quantity of Cu(II) in the organic phase by atomic absorption spectrophotometry. Because higher absorbance ratio was obtained in pH 6.0~7.0, buffer solution at pH 6.5 was used in this measurement. Linear relationship was found between absorbance and concentration in the range of 1.0~4.0${\times}10^{-4}M$. This method might be applicable to the determination of rifampicin in the preparations.

• Journal of IKEEE
• /
• v.17 no.4
• /
• pp.398-406
• /
• 2013

Nuclear medicine imaging devices such as PET diagnose disease after injecting radiopharmaceuticals in human body for diagnosis. Radiopharmaceuticals should maintain the proper pH for human body safety. In general, pH paper is used to measure the pH of the radiopharmaceutical. pH of the sample compared with the standard color chart is used for measurement. However, the pH reading difference according to the experience of a rater can be generated. Also, a pH meter for measuring pH has a high sensitivity and contamination of the sensor must be avoided. In this paper, we developed the new hardware device for pH reading method and software was developed with vision algorithm to measure pH easily and simply.

• Journal of dental hygiene science
• /
• v.12 no.6
• /
• pp.696-701
• /
• 2012

The purpose of this study was to determine pH value of some alcoholic drinks sold in Korea and to provide the basic information which can cause dental erosion. Alcoholic drinks commercially sold were purchased from various big markets in Korea. The sorts of drinks tested in this study consisted of 5 brands of beers, 24 brands of makgeollis, 9 brands of wines and 12 brands of sojus. The test groups were selected randomly and the pH of each beverage was determined using a pH meter he each pH was measured. For statistical data, Mann-Whitney test was used to analyze difference for red wine and white wine and Kruskal-Wallis test was used to compare the pH of each test group. The result of this study was as followings: the mean pH of 5 brands of beers was 4.21, that of 24 brands of makgeollis 3.88, of 9 brands of wines 3.34 and of 12 brans of sojus 7.86. Each test group was significantly different (p<0.05). Except for soju groups, the test groups had a low pH value which can cause dental erosion. In terms of comparing between pH value of red wine and white wine, the result of this study represented that the mean pH of red wine was 3.45 and that of white wine was 3.21. This result showed the pH of two kinds of wine had a low pH which can lead to dental erosion and the difference of two wine were significantly different (p<0.05). As a result, some drinks sold in Korea have a high erosive potential on teeth since they have a comparatively low pH expect soju. Hence, when we consume some kinds of alcoholic drinks, we make sure to remember that the alcoholics which had a low pH, can have an effect on dental erosion that mean we should avoid to drink some alcoholic drinks with low pH for long time.