• Tuberculosis and Respiratory Diseases
• /
• v.48 no.5
• /
• pp.773-780
• /
• 2000

Background : pH measurement is an important test in assessing the etiology of pleurisy and in identifying complicated parapneumonic effusion. Although the blood gas analyzer is the gold standard method' for pleural pH measurement, pH meter & pH strip methods are also used for this purpose interchangably. However, the correlation among the pH data measured by the three different methods needs to be evaluated. In this study, we measured the pH of pleural fluid with the three different methods respectively and evaluated the correlation among the measured data. Methods : From August 1999 to March 2000, we measured the pleural fluid pH in 34 clinical samples with three methods-blood gas analyzer, pH meter, and pH strip. In the blood gas analyzer and pH meter methods, the temperature of pleural fluid was maintained around $0^{\circ}C$ in air-tight condition before analysis and measurement was performed within 30 minutes after collection. As for the pH strip method, the pleural fluid pH was checked in the ward immediately after tapping and in the clinical laboratory of our hospital. This part is unclear. Results : The causes of pleural effusion were tuberculosis pleurisy in 16 cases, malignant pleural effusion 5 cases, parapneumonic effusion 9 cases, empyema 3 cases, and congestive heart failure 1 case. The pH of pleural fluid (mean$\pm$SD) was 7.34$\pm$0.12 with blood gas analyser, 7.52$\pm$0.25 with pH meter, 7.37$\pm$0.16 with pH strip of immediate measurement and 6.93$\pm$0.201 with pH strip of delayed measurement. The pH measured by delayed pH strip measurement was lower than those of other methods (p<0.05). The correlation of the results between the blood gas analyzer and pH meter(p=0.002, r=0.518) and the blood gas analyzer and pH strip of immediate measurement(p<0.001, r=0.607). Conclusion : In the determination of pH of pleural fluid, pH strip method could be a simple and reliable method under immediate measurement conditions after pleural fluid tapping.

• Journal of the Korean Chemical Society
• /
• v.42 no.4
• /
• pp.432-442
• /
• 1998

Since the definition of pH, $pH=-Ioga_H$ is based on a single ion activity, pH values can not be determined with measurement itself, but require an approximation method. They are derived from EMF measurement of a liquid junction free cell using hydrogen and Ag/AgCl electrodes. Primary standard materials with certified pH values can be obtained with this approximation method. Standard buffer solutions are used to calibrate pH meters. Thus the accuracy of the pH values of standard buffer solutions limits the reliability of measured pH values can be obtained with this approximation method. Standard buffer solution are used to calibrate pH meters. Thus the accuracy of the pH values of standard buffer solutions limits the reliability of measured pH values of sample solutions. To certify the pH values, we have established the system for the primary standard measurement and certified the pH of buffer solutions in the range of 1.6∼12.5 pH unit within uncertainty of ${\pm}0.005$ pH unit.

• Journal of Oral Medicine and Pain
• /
• v.40 no.3
• /
• pp.124-129
• /
• 2015

Purpose: Salivary pH is an easily measurable biochemical marker and related to various intraoral and systemic conditions. The aim of this study was to evaluate the reliability of the salivary pH measurement using pH paper. In addition, the normal values of salivary pH using pH paper were compared to those of pH meter to investigate the validity. Methods: Twenty healthy male participants attended this study (mean age, $24.5{\pm}1.47$ years). Unstimulated saliva and stimulated saliva were collected from each subject two times with the interval of a day and salivary pH was immediately measured by the two experienced examiners using pH paper and pH meter. The salivary pH was compared between the groups and inter- and intra-examiner reliability of pH paper was investigated. The intraclass correlation coefficient (ICC) was used to calculate variations. Results: All measurements had good to excellent inter-examiner (ICC 0.755 for unstimulated; 0.760 for stimulated saliva), intra-examiner (ICC 0.635 for unstimulated; 0.592 for stimulated saliva) reliability and two measurement methods using pH paper and pH paper also showed high reliability (ICC 0.852 for unstimulated; 0.640 for stimulated saliva). The values measured by pH paper were significantly lower than those measured by pH meter. Conclusions: pH paper showed adequate inter- and intra-examiner reliability and it presented the validity in terms of comparison with the pH meter as a standard in the salivary pH measurement.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.7 no.6
• /
• pp.331-334
• /
• 2002

Culture conductivity and on-line NADH fluorescence were used to measure cellular growth in plant cell suspension cultures of Podophyllum hexandrum. An inverse correlation between dry cell weight and medium conductivity was observed during shake flask cultivation. A linear relationship between dry cell weight and culture NADH fluorescence was obtained during the exponential phase of batch cultivation In a bioreactor under the pH stat (pH 6) conditions. It was observed that conductivity measurement were suitable for biomass characterisation under highly dynamic uncontrolled shake flask cultivation conditions. However, if the acid/alkali feeding is done for pH control the conductivity measurement could not be applied. On the other hand the NADH fluorescence measurement allowed online-in situ biomass monitoring of rather heterogenous plant cell suspension cultures in bioreactor even under the most desirable pH stat conditions.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.14 no.3
• /
• pp.205-211
• /
• 2011

On board comparison of pH and total alkalinity measurement in seawater was carried out during the JES expedition on R/V Roger Revelle in the East Sea using 550 real seawater samples from the surface to the bottom. Spectrophotometry and potentiometry without liquid junction were compared for pH measurement. The pH values of two methods are generally in a good agreement. Spectrophotometry with a pipette provides higher value compare with the potentiometry in the deep layer, where pH values are lower. However, spectrophotometry without a pipette shows same values with potentiometry within their precision range. The pipetting procedure may remove of $CO_2$ in the sample, which causes increase of pH. Potentiometric titration methods using a closed-cell and an open-cell were compared for the total alkalinity measurement. Values from open cell method are smaller by about 5~10 ${\mu}mol\;kg^{-1}$ than those from closed cell method. This may be caused by the bubble formed in the closed cell during the experiment. Although any analytical method compared in this study for the pH or TA measurement can be applied, special attentions should be paid for satisfactory results.

• Journal of Korean Society for Atmospheric Environment
• /
• v.3 no.2
• /
• pp.53-61
• /
• 1987

Automatic and manual rain smaplers wre installed at the roof of National Institute of Environmental Research (NIER), and the rain sampling and measurement were conducted during the period April to August 31, 1987. The rain sampling and measurement were carried out in the following manners: The 1st : Acidity and conductivity were measured entirely by automatic rain sampler (continuous measurement) The 2nd : Acidity and conductivity wrer measured in the laboratory with the sample that was taken out of automatic rain sampler. The 3rd : Acidity and conductivity were measured in the laboratory with the sample that was taken out of manual rain sampler. Afterwards, those different measurement values were compared each other and the following conclusions were obtained: 1) The pH of the continous measurement by the automatic sampler was lower than that of the laboratory measurement, and it was reversed in case of the conductivity. 2) The significance was recognized at 5% risk ratio for the population mean of difference of the measurement values of the pH and conductivity from both samples. 3) The significance was not recognized at 5% risk ratio by the analysis of variance by one way layout for the pH and conductivity. 4) The significance was recognized at 5% risk ratio by the analysis of variance by two way layouts for the pH conductivity. 5) The significance was recognized at 5% rrisk ratio for the differences of the pH values obtained by oboth samplers, and no significance was recognized for conductivity. 6) In comparison of the measurement values from the two samplers were shown a good correlation for pH; correlation coefficient (r) = 0.63, and regression equation Y = 0.53X + 2.78. For conductivity, the correlation was also excellent; correlation coefficient (r) = 0.53 and regression equation Y = 0.63X + 5.65.

• Journal of the Korean Chemical Society
• /
• v.33 no.2
• /
• pp.203-207
• /
• 1989

The methyl red stock solution was added to sample solution and the absorbance values of this solution were measured at the maximum absorption wavelengths of the acidic form, the basic form, and the isosbestic point of the indicator. From the measurements of absorbance, the pH of this solution was calculated. The range of absorbance at the isosbestic point was maintained within 0.1 ${\sim}$ 0.3. The error of pH measurement was within ${\pm}0.08$ pH unit in the pH range of sample solution of $pK_I{\pm}1$.

• Journal of Sensor Science and Technology
• /
• v.10 no.4
• /
• pp.259-265
• /
• 2001

FET-type dissolved oxygen sensor has the Pt working electrode around the pH-ISFET. Appling a voltage to the working electrode, the hydrogen ion which is proportional to the dissolved oxygen concentration occurs around the pH sensing gate and we can measure the dissolved oxygen concentration by detecting pH concentration through the pH-ISFET. In this paper, a dissolved oxygen measurement system using FET-type dissolved oxygen sensor array which adopt a specific algorithm to enhance the reliability has been developed and we compared its performance with the commercial dissolved oxygen measurement system.

• Nuclear Engineering and Technology
• /
• v.54 no.1
• /
• pp.186-192
• /
• 2022

Flow accelerated corrosion (FAC) is a type of pipe corrosion in which the pipe thickness decreases depending on the fluid flow conditions. In nuclear power plants, FAC mainly occurs in the carbon steel pipes of a secondary system. However, because the temperature of a secondary system pipe is over 150 ℃, in situ monitoring using a conventional ultrasonic non-destructive testing method is difficult. In our previous study, we developed a waveguide ultrasonic thickness measurement system. In this study, we applied a waveguide ultrasonic thickness measurement system to monitor the thinning of the pipe according to the change in pH. The Korea Atomic Energy Research Institute installed FAC-proof facilities, enabling the monitoring of internal fluid flow conditions, which were fixed for ~1000 h to analyze the effect of the pH. The measurement system operated without failure for ~3000 h and the pipe thickness was found to be reduced by ~10% at pH 9 compared to that at pH 7. The thickness of the pipe was measured using a microscope after the experiment, and the reliability of the system was confirmed with less than 1% error. This technology is expected to also be applicable to the thickness-reduction monitoring of other high-temperature materials.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.9
• /
• pp.3375-3379
• /
• 2010

Objective: The purpose of this study was to investigate the characteristics of facial skin parameters (hydration, lipid and pH) on forehead and cheek according to Ayurvedic constitution classification of Vata, Pitta and Kapha. The condition of hydration, lipid and pH in the facial skin was measured using non-invasive diagnostic technique. The collected data was analyzed with the SPSS 16.0 windows statistical program. Design: Eighty-nine Korean female subjects were recruited for this study and the average age of them was $19.9{\pm}0.84$ years. Three groups by the Ayurvedic constitution were classified by questionnaire. Results: There was a significant difference in hydration, lipid and pH according to Ayurvedic constitution. The measurement of hydration on the face depending on the constitution were shown in the order of Pitta, Kapha and Vata (p<0.001). The measurement of lipid on the face depending on the constitution were shown in the order of Kapha, Pitta and Vata (p<0.001, p<0.01). The measurement of pH on the face depending on the constitution were shown in the order of Kapha, Pitta and Vata (p<0.01). Conclusion: Facial skin surface seemed to be dependent on Ayurvedic constitution classification in Korean. These findings indicated that Ayurvedic constitution classification might be a useful esthetic treatment for caring facial skin in the future.