• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2079-2091
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• 2024

In this paper, a model is developed for calculating pH in the presence of organic impurities due to dissolution of paint and/or continuous injection of organic impurities in the sump. The model is implemented in the AnCheBi code for the analysis of chemical behaviors of the iodine in the containment when the pH changes during a severe accident. Validation of the model is performed with P10T2 and P11T1 experiments carried out by AECL in Canada under the BIP project. Importance analyses of the pH calculation model in the AnCheBi code are then performed with the aforementioned experimental data via Latin hypercube sampling on the reaction coefficients, sensitivity analyses of AnCheBi, and calculation of the correlation coefficients between the reaction coefficients and figure of merits (the pH and the concentrations of the various iodine species). From the importance analyses, we provide the sensitivity of the pH calculation model to the change of pH and the concentrations of the various iodine species and the reaction coefficients related with the dominant phenomena underlying the change of pH and the concentrations of the species.

• 대한수의학회지
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• 제44권3호
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• pp.455-462
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• 2004

Change in ${\beta}$-tubulin nucleic acid and protein sequences was the only known difference between Haemonchus contortus fenbendazole (FBZ)-resistant and -susceptible isolates. This change was sufficient to determine the pathologic effect induced by FBZ treatment. This research was initiated to investigate further differences from these two isolates. Since ${\beta}$-tubulin is involved in formation of microtubule, which has functions in secretory vesicle transport, DNase activities from excretory/secretory products (ESP) of the two isolates were compared, based on pH, sensitivity to DNase inhibitors, molecular masses and production of 3'-OH. The most significant difference detected was that a 38.5 kDa DNase activity was identified from ESP of H. contortus FBZ-susceptible isolates but not from those of H. contortus FBZ-resistant isolates. However, it was shown that the 38.5 kDa DNase is expressed with similar level of activity in intestine and whole worm of H. contortus FBZ-resistant and -susceptible isolates. This result demonstrated that the secretory transport pathway of the 38.5 kDa DNase was inhibited by unknown mechanisms, which may be related with ${\beta}$-tubulin sequence change in FBZ-resistant isolates. Other DNases of 34, 36 and 37 kDa were detected from ESP of both H. contortus FBZ-resistant and -susceptible isolates. Overall DNase activities found from ESP of these two isolates were not inhibited by 10 mM EDTA at pH 5.0, but largely inhibited by pH 7.0. In addition, DNase activities in two isolates produced DNA fragments with mixtures of 3'- hydroxyls (OH) and 3'-phosphates (P) at each pH although the 3'-end labeling ratios at pH 5.0 and 7.0 were shown different. Identification of inhibition of the 38.5 kDa DNase secretion in FBZ-resistant isolates suggests existence of further differences, in addition to ${\beta}$-tubulin sequence change, in two isolates. This shows complex effect of FBZ on H. contortus biological mechanisms.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.390-390
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• 2011

The size distribution of gold nanoparticles (NPs) is an important factor in their application to various fields of nanotechnology such as nanodevice fabrication, nanobio measurements, medical diagnosis, and so on, since the properties of nanoparticles depend on the size. As the pH of the reaction mixture was increased, the size distribution of gold NPs synthesized via sodium citrate reduction method was getting narrower and it finally became quite mono-dispersive when the pH was higher than ca. 7. 0.1M NaOH solution was used in controlling the pH, while the ratio between sodium citrate and HAuCl4 was fixed to 3:1 whose initial pH was about 5. Scanning and tunneling electron microscopy and UV/Vis spectrometry were used to characterize the resulting Au NPs. The change of the size distribution of the NPs was discussed with the change of the reaction rate related to the change of hydroxyl ion concentration.

• 센서학회지
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• 제32권2호
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• pp.82-87
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• 2023

This study proposes a pH-dissolved-oxygen monitoring system using 8-HydroxyPyrene-1,3,6-trisulfonic acid Trisodium Salt (HPTS) and tris(4,7-diphenyl-1,10-phenanthroline)Ruthenium(II) chloride (Ru_dpp). Commercial water-quality sensors are electrochemical devices that require frequent calibration and cleaning, are subject to high maintenance costs, and have difficulties conducting measurements in real-time. The proposed pH-dissolved-oxygen monitoring system selects a thin-film sensing layer to measure the change in fluorescence intensity. This change in fluorescence intensity is based on reactions with hydrogen ions in an aqueous solution at a given pH and specific amount of dissolved oxygen. The change in fluorescence intensity is then measured using light-emitting diodes and photodiodes in response to HPTS and Ru_dpp. This method enables the development of a relatively small, inexpensive, and real-time measureable water-quality measurement system.

• 센서학회지
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• 제21권3호
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• pp.223-228
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• 2012

In this study, a fiber-optic pH sensor based on a pH sol-gel film is fabricated. The sol-gel film is made by co-polymerizing tetramethoxysilane, trimethoxymethylsilane, ethanol and distilled water. As a pH indicator, a neutral red is immobilized in a thin porous film formed by the sol-gel process. The pH change in a sensing probe gives rise to a change in the color of the pH sol-gel film, and the absorbance of reflected light through the pH sol-gel film is also changed. By using a spectrometer, therefore, the spectra of reflected lights in the sensing probe with different pH values are measured. Also, the relationships between the pH values and the absorbance are analyzed on the basis of the color variations of the pH sol-gel films. In repeated experiments, the fiber-optic pH sensor shows that it has reversibility, a high reproducibility and a wide absorbance change in a pH range from pH 5 to 9. Also, we confirmed that the fabricated pH sol-gel film exhibits a fast response time, little or no pH indicator leaching and a dynamic range of 2.04 dB from pH 5 to 9. Based on the results of this study, a fiber-optic pH sensor can be developed for the pH monitoring in the harsh environments.

• 한국미생물·생명공학회지
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• 제22권1호
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• pp.59-64
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• 1994

The production and the characteristics of protease produced by Bacillus sp. SH-8 and Bacillus sp. SH-8M were investigated under the different pH conditions. Bacillus sp. SH-8 and Bacillus sp. SH-8M showed the maximum activity of protease at 60 hours(70 units/ml) AND 96 houre(50 units/ml) cultivation, respectively, under the alkaline condition(pH 10.2). However, Bacillus sp. SH-8M exhibited the maximum activities in 8 days cultivation at pH 6.9 and in 6 days cultivation at pH 7.7 Bacillus sp. SH-8M showed the protease activity at the pH change from alkaline to neutral condition, whereas Bacillus sp. SH-8 did not. In addition. all the enzymatic characteristics of protease produced by Bacillus sp. SH-8 and Bacillus sp. SH-8M were similar with the regardless of different pH conditions.

• Journal of the Optical Society of Korea
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• 제10권1호
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• pp.28-32
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• 2006

We propose a new pH-sensing scheme using a methylene blue adsorption on an optical fiber cladding surface. Interactions between the silica and hydroxyl ions of a base solution induce the surface of the silica negatively charged. The charged surface attracts the positively charged chromophores of methylene blue. As the pH of the solution is reduced, the electrostatic attraction will also be reduced. This electrostatic attraction can change the transmitted light intensity of the cladding mode, since the boundary condition changes. We also carried out a simulation to verify the effect from external refractive index change around a long-period fiber grating. Our results confirm that the wavelength shift by external refractive index change is negligible compared to the transmitted light intensity variation of the cladding mode. By using a long-period grating pair, we can detect the cladding mode transmittance variations. Experimentally, we showed the possibility of pH sensing in the $1.5{\mu}m$ infrared region.

• 한국건설순환자원학회논문집
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• 제4권1호
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• pp.62-67
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• 2016

본 연구에서는 순환골재 용출수의 pH가 실제 환경에 미치는 영향을 평가하기 위하여 기존 순환골재 pH 측정방법 중 용매의 종류, 용출시간, 순환골재 크기에 따라 다양한 방법으로 평가하였다. 또한 순환골재가 현장에 재활용 되었을 때를 가정하여 토양에 의한 pH 완충능력을 평가하였고, 현장재현 모형시험을 통해 순환골재 pH가 실제 하천환경에 미치는 영향을 조사하였다. 순환골재에 의한 pH의 오염도는 자연계에서의 실제 오염농도와는 차이가 있음을 확인하였으며, 특히 실제 현장에서 토양층의 확보가 이뤄진다면 토양의 자연정화 능력에 의해 환경에 미치는 영향은 작을 것으로 평가되었다. 또한 순환골재로부터 발생하는 알칼리성의 pH 유출수가 유입되더라도 하천의 자정능력에 의해 pH 영향은 거의 없는 것으로 평가되었다.

• Restorative Dentistry and Endodontics
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• 제40권4호
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• pp.270-275
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• 2015

Objectives: This study examined the color changes of a resin composite with different shades upon exposure to water with different pH. Materials and Methods: Nanohybrid resin composites (Filtek Z350XT, 3M ESPE) with four different shades (A2, A3, B1, and B2) were immersed in water with three different pH (pH 3, 6, and 9) for 14 day. The CIE $L^*a^*b^*$ color coordinates of the specimens were evaluated before and after immersion in the solutions. The color difference (${\Delta}E^*$) and the translucency parameter (TP) were calculated using the color coordinates. Results: ${\Delta}E^*$ ranged from 0.33 to 1.58, and the values were affected significantly by the pH. The specimens immersed in a pH 6 solution showed the highest ${\Delta}E^*$ values (0.87 - 1.58). The specimens with a B1 shade showed the lowest ${\Delta}E^*$ change compared to the other shades. TP ranged from 7.01 to 9.46 depending on the pH and resin shade. The TP difference between before and after immersion in the pH solutions was less than 1.0. Conclusions: The resulting change of color of the tested specimens did not appear to be clinically problematic because the color difference was < 1.6 in the acidic, neutral, and alkaline solutions regardless of the resin shade, i.e., the color change was imperceptible.

• 대한소아치과학회지
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• 제34권4호
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• pp.590-598
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• 2007

유아용 시럽형 약물은 어린이가 쉽게 복용할 수 있도록 여러 종류의 당분을 감미제로 사용하고 있으며 그로 인한 우식의 위험이 높다고 할 수 있다. 그러나 시럽형 약물의 우식유발성에 대한 보호자의 인지도는 매우 낮으며 의료 종사자들 조차 이를 소홀히 여기고 있어 문제의 심각성이 크다고 할 수 있다. 본 연구는 시럽형 약물이 구강 내 산도에 미치는 영향에 대하여 조사할 목적으로, 15 종의 시럽형 약물의 산도를 조사하고, 그 중 널리 시판되는 4종을 선택하여 이 약물들이 치태의 산도 변화에 미치는 영향을 평가하였다. 또한 가장 흔하게 사용하는 유아용 시럽형 약물의 일종인 코푸시럽의 복용방법에 따른 타액의 산도 변화를 측정하여 다음과 같은 결과를 얻었다. 1. 15 종 시럽형 약물의 산도는 pH $3.0{\sim}6.8$의 범위에서 다양하여 평균 pH $4.7{\pm}0.94$로 나타났다. 2. 치태의 산도변화를 측정하기 위해 선정된 4종의 시럽형 약물 모두는 구강 내 투입 직 후 법랑질의 탈회 임계점인 pH 5.5 이하로 치태의 산도를 급격히 떨어뜨렸으며, 시간 경과에 따른 치태의 산도 변화에서 콜디(종합 감기약)를 제외한 모든 약물에서는 유의한 차이가 없었다(p>0.05). 3. 코푸 시럽으로 구강을 헹구어낸 경우와 코푸 시럽에 이어 물로 구강을 헹구어낸 경우 타액의 산도 변화에 있어서는 유의한 차이가 있었다(p<0.05).