• 한국가스학회:학술대회논문집
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• 1997.09a
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• pp.229-235
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• 1997

A low power (300 mW) catalytic bead combustible gas sensor is developed and utilized with a computer controlled sampling system for measuring heat content of natural gas. The heat content of gas is proportional to the change in the energy required to exposure to the sample of combustible gas. The heat content of natural gas samples ranging 36.30 - 39.88 MJ/$m^3$ is measured in the range of approximately $1\%$ error, which is comparable to its nominal heat content. Each gas has a slightly different curve of sensitivity vs. sensor temperature. Thus there Is no temperature at which all sensitivities are equal. In calibration process the choice of a optimum operating temperature is an important factor that influences the overall performance of the measurement system.

• Journal of Sensor Science and Technology
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• v.24 no.5
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• pp.311-318
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• 2015

The excess use and generation of various toxic gases from many industrial complexes and plant facilities have increased the possibility of leakage or explosion accidents, which can cause fatal damage to human beings in the wide range of neighboring area. To prevent the exposure to the fatal toxic gases, it is very important to monitor the leakage of toxic gases using gas sensors in real time. Various types of gas sensors, which can be classified as semiconductor, electrochemical, optical, and catalytic combustion types according to the operating principles, have been developed. In this review, the operation principles of gas sensors are explained and the performance of those sensors is compared. The state-of-the-art gas sensor technologies developed by research institutes or companies are reviewed also.

• Journal of the Korean Institute of Gas
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• v.15 no.4
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• pp.27-32
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• 2011

Management of gas safety is becoming important with increasing use of gas facilities. U-safety system is being promoted as part of national management of gas, and thus real-time and in-situ gas sensor should be developed. Detection method for When the gas sensor is installed in gas conduit, explosion may be likely, because hydrocarbon gases is usually used the difference of thermal resistance between reference and working electrode. Therefore, it is required to detect the hydrocarbons, such as $CH_4$ and CO, at room temperature via electrochemically catalytic reaction. In this study, Pt nanoparticle was doped on the porous gold powder by electrolytic plating method, and then it was used as catalytic electrode for CO oxidation. For Pt/PAu electrode, approximately 21% of CO conversion was obtained. It is noted that Pt/PAu electrode could be used to react the oxidation of hydrocarbon gases at room temperature via applying of external voltage.

• Journal of Sensor Science and Technology
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• v.15 no.2
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• pp.90-96
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• 2006

We have fabricated the Pd-blck/NiCr gate MISFET-type $H_2$ sensor to detect the hydrogen in atmosphere. A differential pair-type structure was used to minimize the intrinsic voltage drift of the MISFET. The Pd-black film was deposited in the argon environment by thermal evaporation. In order to eliminate the blister formation in the surface of the hydrogen sensing gate metal, Pd-black/NiCr double metal layer was deposited on the gate insulator. The scanning electron microscopy and the auger electron spectroscopy was used to analyze their surface morphology and basic structure. The Pd-black/NiCr gate MISFET has been shown high sensitivity and stability more than Pd-planar/NiCr gate MISFET.

• Journal of Sensor Science and Technology
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• v.23 no.5
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• pp.314-319
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• 2014

Here, we review the various methods for the preparation of vanadium dioxide ($VO_2$) films and nanowires, and their potential applications to the sensors such as gas sensor, strain sensor, and temperature sensor. $VO_2$ is an interesting material on account of its easily accessible and sharp Mott metal-insulator transition (MIT) at ${\sim}68^{\circ}C$ in the bulk. The MIT is also triggered by the electric field, stress, magnetic field etc. This paper involves exceptionally sensitive hydrogen sensors based on the catalytic process between hydrogen molecules and Pd nanoparticles on the $VO_2$ surface, and fast responsive sensors based on the self-heating effects which leads to the phase changes of the $VO_2$. These features will be seen in this paper and can enable strategies for the integration of a $VO_2$ material in advanced and complex functional units such as logic gates, memory, FETs for micro/nano-systems as well as the sensors.

• Environmental Engineering Research
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• v.20 no.4
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• pp.397-402
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• 2015

SCR has been popularly approved as one of the most effective means for NOx emission control in heavy-duty and medium-duty vehicles currently. However, high urea dosing would lead to ammonia slip. And $NH_3$ sensor for vehicle emission applications has not been popularly used in real applications. This paper presents experimental studies on the diesel engine urea-SCR system by using a double NOx sensor system that is arranged in the downstream of the SCR catalyst based on ammonia cross-sensitivity. It was shown that the NOx conversion efficiency rised as $NH_3/NOx$ increases and the ammonia slip started from the $NH_3/NOx$ equal to 1.4. The increase of temperature caused high improvement of the SCR reaction rate while the space velocity had no obvious change. The ammonia slip was in advance as catalyst temperature or space velocity increase and the ammonia storage reduced as catalyst temperature or space velocity increase. The NOx real-time conversion efficiency rised as the ammonia accumulative storage increase and reached the maximum value gradually.

• Journal of Sensor Science and Technology
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• v.19 no.3
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• pp.176-183
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• 2010

It is considered that the urea injection DeNOx SCR(selective catalytic reduction) system is the only promising method to satisfy the worldwide NOx emission standards. As for the theoretical aspect, reactants of NO and $NO_2$ with $NH_3$ produce $H_2O$, $N_2$ and $O_2$ which do not harm human beings and environmental as well. The realization of maximum NOx conversion (without using a post oxidation catalyst) is only possible with closed loop controlled urea dosing. It means built-in $NH_3$ gas sensor have to be developed for detecting accurate $NH_3$ concentration for the feedback system. Using YSZ(yttria-stabilized zirconia) as a solid state electrolyte and $In_2O_3$ as a sensing material, this paper aims to study dependable $NH_3$ gas sensor for the promising solution of DeNOx technology, which have a reproducible electric output signal, a high sensitivity and fast response.

• Journal of Sensor Science and Technology
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• v.28 no.1
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• pp.47-51
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• 2019

Sweat-based glucose sensors are being widely investigated and researched as they facilitate painless and continuous measurement. However, because the concentration of sweat glucose is almost a hundred times lower than that of blood glucose, it is important to develop electrochemical sensing electrode materials that are highly sensitive to glucose molecules for the detection of low concentrations of glucose. The preparation of a flexible and ultra-sensitive sensor for detection of sweat glucose is presented in this study. Oxygen and nitrogen are removed from the surface of a polyimide film by exposure to a CO2 laser; hence, laser-induced graphene (LIG) is formed. The fabricated LIG electrode showed favorable properties of high roughness and good stability, flexibility, and conductivity. After the laser scanning, Pt nanoparticles (PtNP) with good catalytic behavior were electrodeposited and the glucose sensor thus developed, with a LIG/PtNP hybrid electrode, exhibited a high order of sensitivity and detection limit for sweat glucose.

• Journal of the korean Society of Automotive Engineers
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• v.9 no.5
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• pp.66-76
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• 1987

The control technique for an electronic engine is studied. For this study an IBM-PC and a throttle body fuel injection system are selected. The computer controls fuel injection, spark timing, exhaust gas recirculation and idle speed. Fuel injection is adjusted either by a feed back signal of a zirconia $O_{2}$ sensor or programmed logic for starting, deceleration, warm ing up and idle modes. When a 3-way catalytic converter is used with the electronic engine control system, CO, THC, and NOx were reduced more than 90% simultaneously.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.358-359
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• 2006

Ru-C nano-composite films were prepared by MOCVD, and their microstructures and their electrode properties for oxygen gas sensors were investigated. Deposited films contained Ru particles of 5-20 nm in diameter dispersed in amorphous C matrix. The AC conductivities associating to the interface charge transfer between Ru-C composite electrode and YSZ electrolyte were 100-1000 times higher than that of conventional paste-Pt electrodes. The emf values of the oxygen gas concentration cell constructed from the nano-composite electrodes and YSZ electrolyte showed the Nernstian theoretical values at low temperatures around 500 K. The response time of the concentration cell was 900 s at 500 K.