• Journal of Sensor Science and Technology
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• v.21 no.3
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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.

• Journal of the Korean Chemical Society
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• v.26 no.4
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• pp.247-249
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• 1982

• YAKHAK HOEJI
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• v.21 no.1
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• pp.27-29
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• 1977

Amoxicillin formed blue color when heated with phophomolybdic acid in adequate condition, and the color showed maximal absorbance at 760nm. Effect of pH, concentration of phosphomolybdic acid and reating time were studied. And a new colorimetric method of determination of amoxicillin was developed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.59-60
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• 2009

• Environmental Engineering Research
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• v.12 no.5
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• pp.224-230
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• 2007

The objectives of this study were to evaluate the change of molecular weight (MW) profiles in natural organic matter (NOM) through various treatment processes (coagulation, granular activated carbon (GAC), and ozonation) using high performance size exclusion chromatography based on ultraviolet absorbance and dissolved organic detection (HPSEC-UVA-DOC). In addition, relationships between MW profiles and disinfection by-production (DBP) formation were evaluated. Each treatment process results in significant different effects on NOM profiles. Coagulation is effective to remove high molecular weight NOM, while GAC is effective to remove low molecular weight NOM. Ozonation removes only a small portion of NOM, while it induces a significant reduction of UV absorbance due to breakdown of the aromatic groups. All treated waters are chlorinated, and chlorination DBPs such as trihalomethanes (THMs) and haloacetic acids (HAAs) are measured under formation potential conditions. Both THM and HAA formation potentials were significantly reduced through the coagulation process. GAC was more effective to reduce THM formation compared to HAA formation reduction, while ozonation showed significant HAA reduction compared to THM reduction.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1196-1198
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• 1995

In this paper, stability improvement of fragile LB films was attempted by monolayers at the air-water interface and crosslinking of the resulting LB films. The spreading polymers were synthesized by radical copolymerization of monoalkyl with oligoethyleneglycol methyl ether, and poly(allylamine) was employed as the subphase polymer. The monolayer properties have been studied by the surface pressure-area($\pi$-A) isotherms. Interaction between polymers and metal ions at the air-water interface and in their LB films were investigated. From the FT-IR(Reflection and Transmission) spectra, the formation of carboxylate ions and the relative orientation of the side chains could be confined. The monolayers were transferable on various substrates, and the resulting LB films were characterized by SEM and VIS-UV absorbance.

• Journal of Powder Materials
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• v.20 no.2
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• pp.125-128
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• 2013

Magnetic and dielectric properties of rubber composites are controlled by using two kinds of high-permeability metal particles with different electrical conductivity (Sendust, Permalloy), and their effect on microwave absorbance has been investigated, focusing on the quasi-microwave frequency band (0.8-2 GHz). Noise absorbing sheets are composite materials of magnetic flake particles of high aspect ratio dispersed in polymer matrix with various filler amount of 80-90 wt.%. The frequency dispersion and magnitude of complex permeability is almost the same for Sendust and Permalloy composite specimens. However, the complex permittivity of the Permalloy composite (${{\varepsilon}_r}^{\prime}{\simeq}250$, ${{\varepsilon}_r}^{{\prime}{\prime}}{\simeq}50$) is much greater than that of Sendust composite (${{\varepsilon}_r}^{\prime}{\simeq}70$, ${{\varepsilon}_r}^{{\prime}{\prime}}{\simeq}0$). Due to the large dielectric permittivity of Permalloy composite, the absorbing band is shifted to lower frequency region. However, the investigation of impedance matching reveals that the magnetic permeability is still small to satisfy the zero-reflected condition at the quasi-microwave frequency band, resulting in a small microwave absorbance lower than 10 dB.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.1
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• pp.45-51
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• 2005

We have developed surface micromachined Infrared ray (IR) focal plane array (FPA), in which single $SiO_{2}$ layer works as an IR absorbing plate and $Pb(Zr_{0.3}Ti_{0.7})O_{2}$ thin film served as a thermally sensitive material. There are some advantages of applying $SiO_{2}$ layer as an IR absorbing layer. First of all, the $SiO_{2}$ has good IR absorbance within $8{\sim}12{\mu}m$ spectrum range. Measured value showed about 60% absorbance of incident IR spectrum in the range. $SiO_{2}$ layer has another important merit when applied to the top of Pt/PZT/Pt stack because it works also as a supporting membrane. Consequently, the IR absorbing layer forms one body with membrane structure, which simplifies the whole MEMS process and gives robustness Ito the structure.

• Journal of Environmental Science International
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• v.10 no.6
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• pp.393-399
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• 2001

This study was carried out to evaluate the pollutant removal efficiencies of the advanced drinking water treatment using ozonation. for raw water, Nakdong River was used. By conducting batch ozonation test, the following results were obtained. when ozone dosage of 5mg/$\ell$was used, preozonation of raw water reduced turbidity, KMnO$_4$consumption, DOC(dissolved organic carbon), UV254 absorbance, THMFP(trihalomethane formation potential) as much as 3.9NTU, 5.5mg/$\ell$, 1.15mg/$\ell$, 0.112 and 0.065mg/$\ell$, respectively. In case of postozonation of sand filtered water, water quality was also improved with decrease in turbidity, KMnO$_4$consumption, DOC, UV254 absorbance and THMFP at the amount of 0.08NTU, 2.6mg/$\ell$, 0.88mg/$\ell$, 0.042 and 0.018mg/$\ell$, respectively. On the other hand, contents of dissolved oxygen increased at the level of 1.3mg/$\ell$ after preozonation process and 1.0mg/$\ell$ after postozonation process. The effect of ozone dosage was higher than that of its contact time for the removal of the pollutants.

• Food Science and Preservation
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• v.6 no.1
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• pp.71-75
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• 1999

Power consumption, mesh size, moisture content, color difference, amylogram of rice flour milled with water soaked rice were compared with that of rice using dry pin mil process. Maximum water absorbance of rice was 35% for 2.5 hr. Power consumption to mill the soaked rice was less than of dry rice by 6.9kW/100Kg. Moisture content of rice flour from the water soaked rice was 2% higher than that of rice flour from dry rice. Population of flour particle was 52.9% of 60 mesh and 32.6% of 60∼80mesh. Gelatinization temperature of rice flour from the water soaked rice was 30C lower than that of rice flour from dry rice. Maximum and minimum viscosity of rice flour from the water soaked rice after boiling were 296 cps and 158 cps, independently. Brightness and whiteness of the rice flour from the water soaked rice were increased upto 10hr soaking and decreased after 17hr soaking. Brightness and whiteness of the rice flour were 96.17 and 96.02, independently.