• Journal of Sensor Science and Technology
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• v.30 no.6
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• pp.376-380
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• 2021

The accurate detection of hydrogen gas molecules is considered to be important for industrial safety. However, the selective detection of the gas using semiconductive metal oxides (SMOs)-based sensors is challenging. Here, we describe the fabrication of H₂ sensors in which a nanocellulose/graphene oxide (GO) hybrid membrane is attached to SnO₂ nanosheets (NSs). One-dimensional (1D) nanocellulose fibrils are attached to the surface of GO NSs (GONC membrane) by mixing GO and nanocellulose in a solution. The as-prepared GONC membrane is employed as a sacrificial template for SnO₂ NSs as well as a molecular sieving membrane for selective H₂ filtration. The combination of GONC membrane and SnO₂ NSs showed substantial selectivity to hydrogen gas (R_air / R_gas > 10 @ 0.8 % H₂, 100 ℃) with noise level responses to interfering gases (H₂S, CO, CH₃COCH₃, C₂H₅OH, and NO₂). These remarkable sensing results are attributed mainly to the molecular sieving effect of the GONC membrane. These results can facilitate the development of a highly selective H₂ detector using SMO sensors.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.67-70
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• 2002

The Stirling cryocooler with helium refrigerant has been widely used for the cooling of the infrared detector, and the alternatives of the helium in the Stirling cryocooler are nitrogen and hydrogen gas. In this study, the performance experiment of the small FPFD(Free Piston and Free Piston) type Stirling cooler and the moving coil type, dual acting linear compressor was performed when the nitrogen and helium is used for the working fluid The results show that the nitrogen refrigerant has small cooling capacity compared with the helium, but the performance characteristics of the linear compressor does not greatly changed.

• Journal of The Korean Astronomical Society
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• v.36 no.spc1
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• pp.145-149
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• 2003

LIST is the Lyman-$\alpha$ Imaging Solar Telescope, a project funded by the Korean government to fly on the second Korean Science and Technology research Satellite (STSat-2) due to launch in December 2005. The Principal Investigator is Dr. Minhwan Jang of Kyung-Hee University and of the Space Payload Research Center (SPARC), a consortium of Korean universities and institutions formed to develop scientific research projects in space. The purpose of the LIST project is to design, build, and operate an instrument on STSat-2 which will make images of the Sun from Earth orbit at the wavelength of the Hydrogen Lyman-a emission line at 121.6 nm. LIST has a simple design concept comprised of a small telescope to image the full disk of the Sun onto a CCD detector and a set of filters to isolate the 121.6 nm wavelength.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.323-324
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• 2005

To found out the degradation characteristic of transformer insulation, insulation materials and electrodes are deposited into transformer oil. They used to heated and make flashover. Due to the thermal and electrical stress added to insulation materials, the density of carbon dioxide and hydrogen included in transformer oil was increased. The gas density can measured by using the gas density detection equipment of gas sensor and air circulation method.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1846-1849
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• 2000

Off-line and on-line partial discharges were measured on a 828MVA, 22kV and direct hydrogen-cooled large turbine generator. Partial discharge tests were conducted using digital partial discharge detector(PDD) and turbine generator analyzer(TGA). PDD and TGA showed that off-line partial discharge pattern seems to be very, similar to that found with on-line. Most of the partial discharge is originating with the stator slot in the three phases. As the partial discharge activity is very low, the stator insulation condition of this generator is very good.

• Journal of Sensor Science and Technology
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• v.7 no.3
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• pp.163-170
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• 1998

An ion energy spectrometer which has the $45^{\circ}$ parallel electrostatic deflection plate was designed and constructed for measuring ion temperature in high temperature plasma. The energy calibration and the energy resolution were studied in detail for a hydrogen ion at the $0.24{\sim}1.92\;keV$ energy using electrostatic accelerator with a duoplasmatron ion source. The voltage of the deflection plate was linearly increased for the decreased ion detector position at the constant ion energy and decreased for the increased ion energy at the fixed ion detector position. The inclination of the deflection plate voltage to the ion energy was between 0.92 and 1.61, and linearly decreased for the increased the ion detector position. The measured energy resolution, which is $4.2%\;{\sim}\;11.6%$ in this experiment region, was improved for the increased ion dector position and ion energy. The relative efficiency was increased for the decreased the ion detector position. The ion energy spectrum of the DC plasma in the multi-purpose plasma generator was measured using this equipment. The ion temperature was 203-205 eV at the discharge voltage 320 V, discharge current 1.7 A.

• Journal of Sensor Science and Technology
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• v.23 no.5
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• pp.342-348
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• 2014

This paper introduced a novel multi-gas sensor detector with simple signal processing algorithm. This device was evaluated by investigating the characteristics of combustible materials using fire-generated smell and smoke. Plural sensors including TGS821, TGS2442, and TGS260X were equipped to detect carbon monoxide, hydrogen gas, and gaseous air contaminants which exist in cigarette smoke, respectively. Signal processing algorithm based on the difference of response times in fire-generated gases was implemented with early and accurately fire detection from multiple gas sensing signals. All fire experiments were performed in a virtual fire chamber. The cigarette, cotton fiber, hair, polyester fiber, nylon fiber, paper, and bread were used as a combustible material. This analyzing software and sensor controlling algorithm were embedded into 8-bit micro-controller. Also the detected multiple gas sensor signals were simultaneously transferred to the personnel computer. The results showed that the air pollution detecting sensor could be used as an efficient sensor for a fire detector which showed high sensitivity in volatile organic compounds. The proposed detecting algorithm may give more information to us compared to the conventional method for determining a threshold value. A fire detecting device with a multi-sensor is likely to be a practical and commercial technology, which can be used for domestic and office environment as well as has a comparatively low cost and high efficiency compared to the conventional device.

• Applied Biological Chemistry
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• v.12
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• pp.43-51
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• 1969

The purpose of this study was to determine protein amino acid contents of some Korean foods by gas-liquid chromatography, and to evaluate this technique as a procedure for the quantitative determination of amino acids in foods. The crude protein content of foods was also estimated from the nitrogen content. 1. Nitrogen content of each food sample was determined previously to adjust the amount of sample for GLC analysis 2. In the analysis of 17 known amino acids, a linear relationship was found between the weight of 13 amino acids of 17 amino acids, the internal standard as well as the injection volume of a mixture and the detector responses for the derivatives of the amino acids. No response for arginine, cystein, histidine, and tyrosine was observed. 3. The relative molar response (RMR) values for the 13 amino acids of standard solution relative to glutamic acid as '1.00' were obtained under normal operating conditions with a hydrogen flame ionization detector. 4. The recovery of amino acids from their mixtures with natural food materials was carried out. The recoveries were essentially quantitative except threonine and serine. An overall mean recovery of 11 amino acids was $101.4{\pm}8.4$ per cent before hydrolysis and $98.1{\pm}8.7$ per cent after hydrolysis of samples. 5. The comparative analysis of the acid hydrolysates of two food samples by gas-liquid and ion-exchange chromatographic analysis were carried out. In white-bait pemmican, only threonine and asparagine amounts by GLC analysis had similar values to those obtained by ion-exchange chromatography. The other seven amino acids gave higher values as measured by GLC than by ion-exchange. With the food sample, soybean, alanine, valine, asparagine, and glutamic acid were in good agreement in two analysis, while leucine, proline, threonine, phenylalanine, and lysine were found in slightly higher concentrations in the GLC analysis. 6. Grant variations of amino acid content were found among samples analyzed. The amino acid contents of each sample were compared with the values found in the literature.

• Analytical Science and Technology
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• v.7 no.3
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• pp.349-359
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• 1994

A gas chromatographic method for analyzing the gas odorants concentration in natural gas was studied. Eight odorants involving TBM and THT were completely separated by using OV-10 column. The optimization of several interrelated key parameters affecting the response of FPD such as hydrogen flow rate, air flow rate and detector temperature were accomplished. A permeation device was used to obtain calibration curves of TBM and THT. This analytical method has applied to measure TBM and THT used as a natural gas odorant blend in natural gas pipeline. In order to elucidate the relationship between odor level and odorant level feasibility test of fragrance meter was demonstrated.

• KSBB Journal
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• v.30 no.4
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• pp.161-165
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• 2015

Lactic acid and its derivatives are widely used in the food, pharmaceutical, and cosmetic industries. It is also a major raw material for the production of poly-lactic acid (PLA), a biodegradable and environmentally friendly polymer and a possible alternative to synthetic plastics derived from petroleum. For PLA production by new strains of lactic acid bacteria (LAB), we screened LAB isolates from shellfish. A total of 51 LAB were isolated from 7 types of shellfishes. Lactic acid production of individual isolates was examined using high-performance liquid chromatography using a Chiralpak MA column and an ultraviolet detector. Lactobacillus plantarum T-3 was selected as the most stress-resistant strain, with minimal inhibition concentrations of 1.2 M NaCl, 15% ethanol, and 0.0020% hydrogen peroxide. In a 1 L fermentation experiment, $\small{D}$-lactic acid production of 19.91 g/L fermentation broth was achieved after 9 h cultivation, whereas the maximum production of total lactic acid was 41.37 g/L at 24 h.