• Journal of Sensor Science and Technology
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• v.30 no.6
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• pp.381-383
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• 2021

Light-activated metal oxide gas sensors have been investigated in recent decades. Light illumination enhances the sensing attributes, including the operational temperature, sensitivity, and selectivity. Unfortunately, high operating temperature is a major problem for gas sensors because of the huge energy consumption. Therefore, the importance of light-activated room-temperature sensing has increased. This paper reviews recent light-activated sensors and their sensing mechanisms with a specific focus on metal oxide gas sensors. Studies use the outstanding ZnO and SnO₂ sensors to research photoactivation when illuminated by various sources such as ultraviolet (UV), halogen lamp, or monochromatic light. Photon induction generates electron-hole pairs that increase the number of adsorption sites of gas molecules and ions improving the sensor's sensing properties.

• Polymer(Korea)
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• v.34 no.6
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• pp.565-573
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• 2010

Copoly(2-(dimethylamino)ethyl methacrylate)(DAEMA)/butyl acrylate (BA) and copoly(methyl methacrylate)(MMA)/BA/2-(cinnamoyloxy)ethyl methacryate (CEMA), which were cross-linked with dibromoalkane and UV irradiation, respectively, were prepared for the precursors of interpenetrating polymer network (IPN) humidity-sensitive films. 3-(Triethoxysilyl)propyl cinnamate (TESPC) was used as a surface-pretreating agent for the attachment of IPN-polyelectrolyte to the electrode surface by UV irradiation. Humidity sensitive polymeric thin films with an IPN structure were prepared by crosslinking reactions of copoly(DAEMA/BA) with 1,4-dibromobutane (DBB) and copoly(MMA/BA/CEMA) by UV-irradiation. The anchoring of an IPN-polyelectrolyte into the substrate was carried out via the photochemical $[2{\pi}+2{\pi}]$ cycloaddition. The resulting humidity sensors showed a high sensitivity in the range of 20~95%RH and a small hysteresis (<1.5%RH). The response time for adsorption and desorption process at 33~94%RH was 48 and 65 s, respectively, indicating a fast response. The effects of the concentration of copolymers, molar ratio of crosslinking agents and time of the precursor solution for dip-coating on their humidity sensitive properties including water durability were investigated.

• Journal of Biosystems Engineering
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• v.15 no.1
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• pp.33-43
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• 1990

Spectral reflectance of paddy, brown rice, milled rice, greenish grain, yellow grain and denatured grain were measured over the range of 340 to 820 nm with "Double Beam Spectrophotometer(Model UV-180)". Variation in the reflectance depending on milling degree of milled rice appeared greatest over the range of 420 to 500 nm, and that between white rice and other rice samples appeared greatest near 500 nm. On the basis of the above results, a whiteness meter to measure milling degree of rice was manufactured using tungsten lamp, photodiodes and amplifier, and its performance was compared with the existing whiteness meters (KETT and Z-II optical sensor). There were very high correlations among those whiteness meters.

• Electrical & Electronic Materials
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• v.10 no.5
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• pp.419-424
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• 1997

It is well known that the metallo-phthalocyanines (MPcs) are sensitive to toxic gaseous molecules such as NO$_2$ as well as are chemically and thermally stable. Therefore, lots of MPcs have been studied as the potential chemical sensor for NO$_2$gas using quartz crystal microbalance(QCM) or electrical conductivity. In this study, thin films of octa(2-ethylhexyloxy)copper-phthalocyanine were prepared by Langmuir-Blodgett method and characterized by using UV-VIS absorption spectroscopy and ellipsometry. Optimal transfer condition of LB films was investigated and preliminary results of current-voltage(I-V) characteristics of these films exposed to NO$_2$gas as a function of film thickness, temperature and concentration were discussed.

• Rapid Communication in Photoscience
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• v.4 no.4
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• pp.88-90
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• 2015

The design and development of fluorescent chemosensors have recently been intensively explored for sensitive and specific detection of environmentally and biologically relevant metal ions in aqueous solution and living cells. Herein, we report the photophysical results of rhodamine B based fluorogenic and chromogenic receptor for selective copper detection in the complete organic or mixed aqueous-organic media at neutral pH under ambient condition. The ligand exhibited the remarkable increment in the fluorescence emission and UV-visible absorption signal intensities at 587 and 547 nm, respectively, on induction of copper ion while the ligand solution remain completely silent on addition of varieties of other metal ions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.167-170
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• 1998

The electrical characteristics of Stearic acid LB films were investigated to develop the gas sensor using Langmuir-Blodgett(LB) films. The deposition status of LB films were verified by the measurements of UV absorbance and I-V characteristics. The conductivity of Stearic acid LB films at room temperature was $10^{-8}[S/cm]$, which is typical of semiconductor. The conductivity was found to increase as the temperature was increased. The acitivation energy was about 1[eV].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.150-153
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• 1997

Langmuir-Blodgett(LB) technique is one of the ways of fabricating organic ultra-thin films. It is well known that It has the advantage to control the alignment and orientation of the molecules in the films. Metallo-phthalocyanines(MPcs) are sensitive to electron affinitive toxic gaseous molecules, such as NO$_2$, NO, SO$_2$. MPcs are thermal, optical, mechanical, chemical stable. Therefore, it is interesting to prepare phthalocyanine LB films containing copper as a chemical sensor for NO$_2$ and SO$_2$ gas and test their sensitivity to these toxic gases. In this study, thin films of Octa-dodecylosy copper-phthalocyanine were prepared by LB technique. $\pi$-A isotherm, transfer ratio, UV-VIS. spectroscopy of these films were investigated. Also current-voltage(I-V) characteristics of these was auto investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.146-149
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• 1997

It is well known that the metallo-phthalocyanines(MPcs) are sensitive to toxic gaseous molecules, such as NO$_2$, NO, SO$_2$. MPcs are thermally, optica1ly, mechanically and chemically stable. Therefore, it is interesting to prepare phthalocyanine LB films containing tin as a chemical sensor for NO$_2$ and SO$_2$ gas and test their sensitivity to these toxic gases. Frist, in this study, ultra thin films of Octa-dodecyloxy tin-phthalocyanine were prepared on various substrates by LB technique. Langmuir-Blodgett(LB) technique is one of the ways of fabricating organic thin films. It has the advantage to control the alignment and orientation of the molecules in the films. $\pi$-A isotherm and transfer ratio of tin-phthalocyanine derivative. UV-VIS. spectroscopy were investigated. Also intrinsic current-voltage(1-V) characteristics of these films was investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.194-197
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• 1997

The LB technique is one of the most powerful fabricating methods of organic ultra-thin film, which deposits a monolayer films in molecular level on the surface of the substrate. We have investigated the electrical characteristics of Myristic acid, Stearic acid and Arachidic acid LB films for horizontal direction to develop for the gas sensor. The optimum conditions for a film deposition were obtained by measurement of $\pi$-A isotherm. The status of the deposited film was confirmed by measurement of UV absorbance. We could distingished the difference of I-V characteristics for the fatty acid for the horizontal direction. The conductivity of fatty acid LB films for horizontal direction was 10$^{-7}$ ~ 10$^{-9}$ [S/cm] that mean like semiconductor.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.606-611
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• 2002

Welding using lasers can be mass-produced in high speed. In the laser welding, performing real-time monitoring system of the welding quality is very important in enhancing the efficiency of welding. In this study, the plasma and molten metal which are generated during laser welding were measured using the UV sensor and IR sensors. The results of laser welding were classified into five categories such as optimal heat input, little low heat input, low heat input, partial joining due to gap mismatch, and nozzle deviation. Also, a system was formulated which uses the measured signals with a fuzzy pattern recognition method which is used to perform real-time evaluation of the welding quality and the defects which can occur in laser welding.