• Journal of Semiconductor Engineering
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• v.1 no.1
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• pp.46-56
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• 2020

This article highlights new opportunities of inorganic semiconductor materials for bio-implantable electronics, as a subset of 'transient' technology defined by an ability to physically dissolve, chemically degrade, or disintegrate in a controlled manner. Concepts of foundational materials for this area of technology with historical background start with the dissolution chemistry and reaction kinetics associated with hydrolysis of nanoscale silicon surface as a function of temperature and pH level. The following section covers biocompatibility of silicon, including related other semiconductor materials. Recent transient demonstrations of components and device levels for bioresorbable implantation enable the future direction of the transient electronics, as temporary implanters and other medical devices that provide important diagnosis and precisely personalized therapies. A final section outlines recent bioresorbable applications for sensing various biophysical parameters, monitoring electrophysiological activities, and delivering therapeutic signals in a programmed manner.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.6
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• pp.652-658
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• 1997

Coagulant feeding control is very important in the water treatment process. Coagulant feeding is related to the raw water quality such as turbidity, alkalinity, water temperature, pH and so on. However, since the process of chemical reaction has not been clarified so far, coagulant dosing rate has been decided by jar-test. In order to overcome the difficulty mentioned above, Fuzzy Neural Network to fuse fuzzy logic and neural network was proposed, and the scheme was applied to the automatic determination of coagulant dosing rate. This algorithm can automatically identify the if-then rules, tune the membership functions by utilizing expert's experimental data. The proposed scheme is evaluated by computer simulation and interfaced with coagulant feeder operated by magnetic flowmeter, control valve and PLC. It is shown that coagulant feeding according to real time sensing of water quality is very effective.

• Advances in aircraft and spacecraft science
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• v.2 no.3
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• pp.263-273
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• 2015

Carbon nanotube strain sensors, or so called "fuzzy fiber" sensors have not yet been studied sufficiently. These sensors are composed of a bundle of fiberglass fibers coated with CNT through a thermal chemical vapor deposition process. The characteristics of these fuzzy fiber sensors differ from a conventional nanocomposite in that the CNTs are anchored to a substrate fiber and the CNTs have a preferential orientation due to this bonding to the substrate fiber. A numerical model was constructed to predict the strain response of a composite with embedded fuzzy fiber sensors in order to compare result with the experimental results obtained in an earlier study. A comparison of the numerical and experimental responses was conducted based on this work. The longitudinal sensor output from the model matches nearly perfectly with the experimental results. The transverse and off-axis tests follow the correct trends; however the magnitude of the output does not match well with the experimental data. An explanation of the disparity is proposed based on microstructural interactions between individual nanotubes within the sensor.

• Journal of Sensor Science and Technology
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• v.19 no.5
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• pp.356-360
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• 2010

Due to the high surface-to-volume ratio, the 3-dimensional(3D) nanostructures of metal oxides are regarded as the best candidate materials for the chemical gas sensors. Here we have synthesised flower-like 3D zinc oxide nanostructures through a simple hydrothermal route. Specific surface area of the 3D zinc oxide nanostructures synthesised in different pH values from 9.0 to 12.0 were evaluated by using a BET analyzer and the results were compared with that of a zinc oxide thin film fabricated by rf sputtering. Using interdigitated electrodes, superior CO gas sensing properties of the 3D zinc oxide nanostructures on the ZnO thin film to those of the ZnO thin film were demonstrated.

• Textile Coloration and Finishing
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• v.24 no.4
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• pp.233-238
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• 2012

The opto-functional materials have been developed as a promising research topic toward the end uses for optical materials and applications. The attractive area in this part was the design of sensor molecules for detecting harmful environmental factors. These harmful factors impart undesired effects on wide range of chemical and biological phenomenon. In this context, many researchers have studied luminescence chemosensor materials. These sensor molecules showed optical signals such as color or fluorescence change by detecting harmful environmental factors. In this study, the novel fluorescence chemosensor 1 has been designed and synthesized through reaction of rhodamine 6g hydrazide and 2-hydroxy-1-naphthaldehyde. The chemosensor 1 had been analyzed by UV-Vis and fluorescence spectrophotometer. We found that this chemosensor 1 has 'off-on' and dual type sensing properties toward $Cu^{2+}$ and $Mg^{2+}$.

• Textile Coloration and Finishing
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• v.25 no.3
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• pp.153-158
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• 2013

In this study, pyrene based chemosensor was synthesized by two step reaction. The chemosensor showed that high selectivity toward fluoride in DMSO. The fluorescence intensity was drastically increased by binding between chemosensor and fluoride ion. Absorption and fluorescence spectra were obtained by UV-Vis spectrometer and fluorescence spectrophotometer. The binding ratio between chemosensor and fluoride ion was also investigated by job's plot method and Benesi-Hildebrand plot. The HOMO/LUMO energy levels and electron distribution were calculated and simulated by Material studio 6.0 Package.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1203-1205
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• 2003

To detect dust-loaded air-mass over land and ocean, we propose an index, which is essentially the difference in Rayleigh-corrected reflectance between 412 and 443 nm bands of SeaWiFS. Radiative transfer simulations are conducted to show that the index is linearly related to the optical thickness of modeled dust-contaminated aerosol while showing insensitivity against non-absorbing model aerosols. Asian SeaWiFS data set of 2001 spring is used to produce daily composite imagery of the index, which compares well with TOMS Aerosol Index and with predicted aerosol optical thickness predicted by CFORS chemical weather forecast.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1194-1196
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• 2003

Variations in soil physical and chemical properties can affect agricultural productivity and the environmental implications of crop production. These variations are present and may be important at regional, field, and sub-field (precision agriculture) scales. Because traditional measurements are time-consuming and expensive, reflectance-based estimates of soil properties such as texture, organic matter content, water content, and nutrient status are attractive. Soil properties have been related to reflectance measured with laboratory, in-field, airborne, and satellite sensors. Both multispectral and hyperspectral instruments have been used, with both natural and artificial illumination. Varying levels of accuracy have been obtained, with the best results (r > 0.95) using hyperspectral reflectance data to estimate soil organic matter and water content.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.576-578
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• 2003

Hyperspectral image divides VNIR region to over 200 bands which can show continuous spectrum with 10 nm spectral resolution. This property is useful in geology where a spectral feature which is decided by chemical compositions and crystalline structures is recorded well. While this field has been studied variously in foreign countries, the studies are in the early stage in Korea. In this study, characteristic materials associated with AMD were classified by using EO-1 HYPERION data which is a spaceborne hyperspectral image and topographical map and DEM and geochemical map were analyzed in conjunction with the image in order to examine that classified minerals are secondary minerals by AMD.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.189.1-189.1
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• 2013

Titanium dioxide (TiO2) is a wide bandgap semiconductor possessing photochemical stability and thus widely used for photocatalysis. However, enhancing photocatalytic efficiency is still a challenging issue. In general, the efficiency is affected by physio-chemical properties such as crystalline phase, crystallinity, exposed crystal facets, crystallite size, porosity, and surface/bulk defects. Here we propose an alternative approach to enhance the efficiency by studying interfaces between thin TiO2 layers to be stacked; that is, the interfacial phenomena influencing on the formation of porous structures, controlling crystallite sizes and crystallinity. To do so, multi-layered TiO2 thin films were fabricated by using a sol-gel method. Specifically, a single TiO2 thin layer with a thickness range of 20~40 nm was deposited on a silicon wafer and annealed at $600^{\circ}C$. The processing step was repeated up to 6 times. The resulting structures were characterized by conventional electron microscopes, and followed by carrying out photocatalytic performances. The multi-layered TiO2 thin films with enhancing photocatalytic efficiency can be readily applied for bio- and gas sensing devices.