• Bulletin of the Korean Chemical Society
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• v.32 no.spc8
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• pp.2933-2937
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• 2011

A new highly selective receptor (3) based on an acridine-imidazolium functionalized cholestane for anion sensing was designed and synthesized. A binding study of 3 with various anions was assessed by UV-vis and fluorescence spectroscopies in dry CH3CN. Receptor 3 showed the highest selectivity toward hydrogen pyrophosphate (Ka = $1.5{\times}10^4M^{-1}$).

• Journal of Sensor Science and Technology
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• v.31 no.6
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• pp.397-402
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• 2022

In this short review, we explore the recent progress in metal-based gas-sensing techniques. The strong interaction between the metal films and hydrogen gas can be considered to play a considerably important role in the gas-sensing technique. The physical and chemical reactions in Pd-Pd hydride systems were studied in terms of the phase transition and lattice expansion of the metals. Two types of represented detection, electrical and optical, were introduced and discussed along with their advantages.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.5
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• pp.525-532
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• 2014

The sensing of a stack coolant deficiency is very important in that cooling performance of a fuel cell, overheating prevention of a stack or coolant heater. This paper explains the performance comparison between the coolant contact/noncontact level sensors and coolant deficiency sensing logic using the pressure sensor in a stagnant or circulating flow. Throughout the comparison, the pressure sensor is more suitable than the other sensors in terms of the precision, fast response, sensing frequency. After the experiment, the pressure sensor is equipped to an FCEV(Fuel Cell Electric Vehicle) to verify sensing definitely. There was no miss-sensing using pressure sensor while FCEV runs in the conditions of the paved road and cross country road.

• Journal of Sensor Science and Technology
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• v.8 no.6
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• pp.448-453
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• 1999

A Pd-SiC Schottky diode for detection of hydrogen gas operating at high temperature was explored. Hydrogen-sensing behaviors of Pd-SiC Schottky diode were analyzed as a function of hydrogen concentration and temperature by I-V and ${\Delta}I$-t methods under steady-state and transient conditions. The effect of hydrogen adsorption on the barrier height was investigated. Analysis of the steady-state kinetics using I-V method confirmed that the atomistic hydrogen adsorption process is responsible for the barrier height change in the diode.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.3
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• pp.298-305
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• 2016

In this study, we treated pitch-based activated carbon fibers (ACFs) in hydrogen peroxide using electron beam (E-beam) irradiation to improve nitrogen monoxide (NO) sensing ability as an electrode material of gas sensor. The specific surface area of ACFs treated by E-beam irradiation with 400 kGy increased from $885m^2/g$ (pristine) to $1160m^2/g$ without any changes in structural property and functional group. The increase in specific surface area of the E-beam irradiated ACFs enhanced NO gas sensing properties such as response time and sensitivity. When the ACFs irradiated with 400 kGy, response time was remarkably reduced from 360 s to 210 s and sensitivity was increased by 4.5%, compared to the pristine ACFs. These results demonstrate convincingly that surface modification of ACFs using E-beam in hydrogen peroxide solution can enhance textural properties of ACFs and NO gas sensing ability of gas sensor at room temperature.

• Journal of the Korean institute of surface engineering
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• v.50 no.2
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• pp.125-130
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• 2017

ZnO nanowires were synthesized and annealed at various temperatures of $500-800^{\circ}C$ in oxygen atmosphere to investigate hydrogen gas sensing properties. The diameter and length of the synthesized ZnO nanowires were approximately 50-100 nm and a few $10s\;{\mu}m$, respectively. $H_2$ gas sensing performance of the ZnO nanowires sensor was measured with electrical resistance changes caused by $H_2$ gas with a concentration of 0.1-2.0%. The response of ZnO nanowires at room temperature to 2.0% $H_2$ gas is found to be two times enhanced by annealing process in $O_2$ atmosphere at $800^{\circ}C$. In the current study, the effect of heat treatment in $O_2$ atmosphere on the gas sensing performance of ZnO nanowires was studied. And the underlying mechanism for the sensing improvement of the ZnO nanowires was also discussed.

• Journal of Sensor Science and Technology
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• v.29 no.2
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• pp.105-111
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• 2020

Interest and demand for hydrogen sensors are increasing in the field of H₂ leakage detection during storage/transport/use and detection of H₂ dissolved in transformer oil for safety issues as well as in the field of breath analysis for non-invasively diagnosing a number of disease states for a healthy life. In this study, various ZnO-based sensors were synthesized by controlling the reduction in crystallite size, decoration of Pt nanoparticles, doping of electron donating atoms, and doping of various atoms with different ionic radii. The sensing response of the various prepared ZnO-based nanoparticles and quantum dots (QDs) for 10 ppm H₂ was investigated. Among the samples, the smallest-sized (3.5 nm) In³⁺-doped ZnO QDs showed the best sensing response, which is superior to those in previously reported hydrogen sensors based on semiconducting metal oxides. The higher sensing response of In-doped ZnO QDs is attributed to the synergic effects of the increased number of oxygen vacancies, higher optical band gap, and larger specific surface area.

• Korean Journal of Materials Research
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• v.18 no.10
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• pp.529-534
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• 2008

The hydrogen gas sensing properties of a zinc oxide nanowire structure were studied. Porous zinc oxide nanowire structures were fabricated by oxidizing zinc deposited on a single-wall carbon nanotube (SWNT) template. This revealed a porous ZnO-SWNT composite due to the porosity in the SWNT film. The gas sensing properties were compared with those of zinc oxide thin films deposited on SiO2/Si substrates in sensitivity and operating temperature. The composite structure showed higher sensitivity and lower operating temperature than the zinc oxide film. It showed a response even at room temperature while the film structure did not.

• Korean Journal of Materials Research
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• v.19 no.6
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• pp.325-329
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• 2009

Titanium dioxide thin films were fabricated as hydrogen sensors and its sensing properties were tested. The titanium was deposited on a $SiO_2$/Si substrate by the DC magnetron sputtering method and was oxidized at an optimized temperature of $850^{\circ}C$ in air. The titanium film originally had smooth surface morphology, but the film agglomerated to nano-size grains when the temperature reached oxidation temperature where it formed titanium oxide with a rutile structure. The oxide thin film formed by grains of tens of nanometers size also showed many short cracks and voids between the grains. The response to 1% hydrogen gas was ${\sim}2{\times}10^6$ at the optimum sensing temperature of $200^{\circ}C$, and ${\sim}10^3$ at room temperature. This extremely high sensitivity of the thin film to hydrogen was due partly to the porous structure of the nano-sized sensing particles. Other sensor properties were also examined.

• Transactions of the KSME C: Technology and Education
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• v.3 no.4
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• pp.291-297
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• 2015

As promising future energy source, hydrogen has been drawing much attention; however, it is easily leaked from the small gap in any storage container due to its find molecule size. In this study, Laser induced breakdown spectroscopy(LIBS) was used for hydrogen leak detection, and feasibility of the scheme was evaluated based on different way for plasma generation. Laser power of 295 mW was required for generating plasma on metal surface to measure hydrogen atomic emission while approximately 2.5 times higher laser power was needed for plasma formation directly in the hydrogen gas stream. It was shown that peak to base ratio increased linearly with increasing the concentration of hydrogen. It can be concluded that LIBS is a viable technique for hydrogen sensing when the concentration of hydrogen is less than 5%.