• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.11
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• pp.963-968
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• 2002

In this work, porous silicon (PS) layer is investigated as a sensing material to detect organic vapors such as ethanol (called alcohol), methanol, and acetone in low concentrations. To do this, PS sensors were fabricated. They have a membrane structure and comb-type electrodes were used to detect the change of electrical resistance effectively. PS layer on Si substrates was formed by anodization in HF solution of 25%. From fabricated sensors, current-voltage (Ⅰ-Ⅴ) curves were measured for gases evaporated from 0.1 to 0.5% organic solution concentrations at 36$\^{C}$. As the result, all curves showed rectifying behavior due to a diode structure between Si and the PS layer. The conductance of most sensors increased largely at high voltage of 5V, but the built-in potential on the measured Ⅰ-Ⅴ curve was lowered inversely by the adsorption effect of the organic vapors with high dipole moment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.569-572
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• 2001

Selective. highly stable determination of epinephrine(adrenalin) was achieved in cyclic voltammetric measurement carried out at electrochemically treated conductive boron-doped diamond electrode. Boron-doped diamond electrodes were prepared on single crystal Si wafers by microwave plasma chemical vapor deposition and $B_{2}O_{3}$ was dissolved in acetone/methanol(9:1) mixture solution so that the B/C weight ratio ca. $10^{4}ppm$. Epinephrine is a kind of catecholamines, which secreted from adrenal marrow cells. The serious problem to detection of epinephrine is the interference phenomena of electroactive constituent. including AA. In this study. electrochemical treatment of BDD was carried out to discriminate between epinephrine and AA responses. Experimental results showed that the peak potential of AA oxidation shift to the positive direction and the oxidation peak of epinephrine was unchanged. The effect of electrochemical treatment was maintained up to 40hrs.

• Journal of Integrative Natural Science
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• v.2 no.3
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• pp.211-214
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• 2009

A new porous silicon (PSi) microcavity sensor for the detection of volatile organic compounds (VOCs) was developed. PSi microcavity sensor exhibiting unique reflectivity was successfully obtained by an electrochemical etching of silicon wafer. When PSi was fabricated into a structure consisting of two high reflectivity muktilayer mirrors separated by an active layer, a microcavity was formed. This PSi microcavity is very sensitive structures. Reflection spectrum of PSi microcavity indicated that the full-width at half-maximum (FWHM) was of 10 nm and much narrower than that of fluorescent organic molecules or quantum dot. The detection of volatile organic compounds (VOCs) using PSi microcavity was achieved. When the vapor of VOCs condensed in the nanopores, the refractive indices of entire particle increased. When PSi microcavity was exposed to acetone, ether, and toluene, PSi microcavity in reflectivity was red shifted by 28 nm, 33 nm, and 20 nm for 2 sec, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.569-572
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• 2001

Selective, highly stable determination of epinephrine(adrenalin) was achieved in cyclic voltammetric measurement carried out at electrochemically treated conductive boron-doped diamond electrode. Boron-doped diamond electrodes were prepared on single crystal Si wafers by microwave plasma chemical vapor deposition and B$_2$O$_3$ was dissolved in acetone/methanol(1:1) mixture solution so that the B/C weight ratio ca. 10$^3$ppm.. Epinephrine is a kind of catecholamines, which secreted from adrenal marrow cells. The serious problem to detection of epinephrine is the interference phenomena of electroactive constituent, including AA. In this study, electrochemical treatment of BDD was carried out to discriminate between epinephrine and AA responses. Experimental results showed that the peak potential of AA oxidation shift to the positive direction and the oxidation peak of epinephrine was unchanged. The effect of electrochemical treatment was maintained up to 40hrs.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.167-169
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• 2002

Selective, highly stable determination of serotonin was achieved in cyclic voltammetric measurement carried out at electrochemically treated conductive boron-doped diamond electrode. Boron-doped diamond electrodes were prepared on single crystal Si wafers by microwave plasma chemical vapor deposition and $B_2O_3$ was dissolved in acetone/methanol(9:1) mixture solution so that the B/C weight ratio ca. $10^4ppm$. Serotonin is a kind of indoleamines, which secreted from adrenal marrow cells. The serious problem to detection of serotonin is the interference phenomena of electroactive constituent, including AA. In this study, electrochemical treatment of HDD was carried out to discriminate between serotonin and AA responses. Experimental results showed that the peak potential of AA oxidation shift to the positive direction and the oxidation peak of serotonin was unchanged.

• Applied Chemistry for Engineering
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• v.31 no.3
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• pp.317-322
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• 2020

Hydroxylammonium nitrate (HAN; NH₃OHNO₃) is an ionic energy material having a low melting temperature and vapor pressure with a high oxygen balance. To utilize it as an oxidizer for a high content liquid mono-propellant, a dual solvent was used to obtain HAN in a solid particulate form. The dehydrated crystal from an aqueous HAN was washed with dual organic solvents including acetone and ethanol, finally resulting in the moisture content of 13.8 wt%. When acetone was applied as a single solvent, the maximum synthesis yield of 88%, the HAN content evaluated by TGA of 86.2%, and the decomposition temperature ranged 160℃ to 205℃ were achieved.

• Korean journal of applied entomology
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• v.31 no.2
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• pp.182-189
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• 1992

The influnces of 9 kinds of solvents on the toxicities against several insect species, phytotoxicity and solubility of compounds were evaluated by means of leaf dipping and spray methods. In case of the spray application, density and vapor pressure seemed to be a contributing factor to lethal toxicity against brown planthopper and diamond-back moth, respectively; the bigger the property of density and the smaller the vapor pressure gave the stronger toxicity. It appeared that the toxicity of solvents was not correlated with anyone of physical properties such as boiling point, dipole moment, dielectric constant, surface tension and viscosity. Spray treatment gave more toxicity to insects than leaf dipping treatment. Although dielectric constant and dipole moment seemed to be contributing factors to phytotoxic damage to rice seedling and bean plants, respectively, no general correlation between phytoxicity and the other physical properties was found. Leaf dipping application caused stronger phytotoxicity than spray application. It is concluded that 5% acetone solution may be most suitable to test chemicals because of its favorable solubility of compounds, lower toxicity to insects, and lower phytotoxicity.

• Advances in nano research
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• v.13 no.2
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• pp.187-197
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• 2022

The synthesis of organic and hybrid organic-inorganic perovskites directly from solution improves the cost- and energy-efficiency of processing. To date, numerous research efforts have been devoted to investigating the influence of the various solvent parameters for the synthesis of lead halide perovskites, focused on the effects of different single solvents on the efficiency of the resulting perovskites. In this work, we investigated the effect of solvent blends for the first time on the structure and phase of perovskites produced via the Lewis base vapor diffusion method to develop a new synthetic approach for water-stable CsPbBr₃ particles with nanometer-sized dimensions. Solvent blends prepared with DMF and water-miscible solvents with different Gutmann's donor numbers (D_N) affect the Pb ions differently, resulting in a variety of lead bromide species with various colors. The use of a DMF/isopropanol solvent mixture was found to induce the formation of the Ruddlesden-Popper perovskite based on lead bromide. This perovskite undergoes a blue color shift in the solvated state owing to the separation of nanoplatelets. In contrast, the replacement of isopropanol with DMSO, which has a high DN, induces the formation of spherical CsPbBr₃ perovskite nanoparticles that exhibit green emission. Finally, the integration of acetone in the solvent system leads to the formation of lead bromide complexes with a yellow-orange color and the perovskite CsPbBr₃.

• Biomaterials and Biomechanics in Bioengineering
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• v.1 no.1
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• pp.13-25
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• 2014

In the current study, a drug-eluting stent coated with biodegradable polymers and sirolimus was developed by using an ultrasonic nanocoater and characterized in aspects of surface smoothness and coating thickness. In addition, in vitro release profiles of sirolimus by changing top coating layer with different biodegradable polymers were investigated. Smooth surfaces with variable thickness could be fabricated by optimizing polymer concentration, flow rate, nozzle-tip distance, gas pressure, various solvents and ultrasonic power. Smooth surface could be generated by using volatile solvents (acetone, chloroform, and methylene chloride) or post-treating with solvent vapor. Coating thickness could be controlled by varying injection volume or polymer concentration, and higher concentration could reduce the coating time while obtaining the same thickness. The thickness measurement was the most effectively performed by a conventional cutting method among three different methods that were investigated in this study. Release profiles of sirolimus were effectively controlled by changing polymers for top layer. PLGA made the release rate 3 times faster than PDLLA and PLLA and all top layers prevented burst release at the initial phase of profiles. Our results will provide useful and informative knowledge for developing drug-eluting stents, especially coated with biodegradable polymers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.11
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• pp.727-730
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• 2015

In this paper, we fabricated organic compounds detector using the MWCNT/PMMA (multi-walled carbon nanotube / polymethylmethacrylate) composite film. We used polymer film as a matrix material for the device framework, and introduced CNTs for reacting with the organic compounds resulting in changing electrical conductivity. Spray coating method was used to form the MWCNT/PMMA composite film detector, and pattern formation of the detector was done by shadow mask during the spray coating process. We investigated changes of electrical conductivity of the detector before and after the organic compounds exposure. Electrical conductivity of the detector tended to decrease after the exposure with various organic compounds such as acetone, tetrahydrofuran (THF), toluene, and dimethylformamide (DMF). Finally we conclude that organic compounds detection by the MWCNT/PMMA composite film detector was possible, and expect the feasibility of commercial MWCNT/PMMA composite film detector for various organic compounds.