• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.3
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• pp.448-453
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• 1998

An inverted, stagnation point flow OMVPE reactor was studied by laser Raman spectroscopy. Pure rotational Raman scattering by the carrier gas $(N_2; or; H_2)$ was used to determine the axial centerline temperature profile in the reactor as a function of the inlet flow velocity and the rector aspect ratio. A larger temperature gradient normal to the susceptor surface was obtained with higher gas glow velocity, larger aspect ratio, and the use of a $N_2$ carrier gas.

• Journal of Sensor Science and Technology
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• v.30 no.1
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• pp.36-41
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• 2021

The motivation of this paper is to easily analyze the properties of nondispersive infrared gas sensor that has more than two different optical path length and to suggest the criterion and definition of infrared light absorbance in order to minimize the measurement errors. With the output voltage ratios and the normalized derivatives of infrared ray (IR) absorbance, when the normalized derivatives of IR absorbance decreases from 0.28 to 0.10, the lower and higher limits of errors were decreased from -5.62% and 2.39% to -4.27% and 2.78%. When the normalized derivatives of IR absorbance were 0.10, the output voltage could be partitioned into two regions with one exponential equation and the temperature compensation error was less than 5%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.365-365
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• 2008

In this work, Ga-doped ZnO (GZO) thin films for NOx gas sensor application were deposited on low temperature co-fired ceramics (LTCC) substrates, by RF magnetron sputtering method. The LTCC substrate is one of promising materials for this application since it has many advantages (e.g., low cost production, high manufacturing yields and easy realizing 3D structure etc.). The LTCC substrates with thickness of 400 pm were fabricated by laminating 12 green tapes which consist of alumina and glass particle in an organic binder. The structural properties of the fabricated GZO thin films with different thickness are analyzed by X-ray diffraction method (XRD) and field emission scanning electron microscope (FESEM). The GZO gas sensors are tested by gas measurement system under varing operation temperature and show good performance to the NOx gas in sensitivity and response time.

• Journal of the Korea Safety Management & Science
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• v.17 no.2
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• pp.229-234
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• 2015

Depending on the living styles, the types of energy consumed by households have changed, and the consumption has increased rapidly. Consequently, those have led to environmental issues, such as exhaustion of energy and the climate changes. As one of solutions to such issues, energy efficiency can be approached. Therefore, in this study, the gas water heater(115S type Rheem products) that made in Germany and obtain hot water using gas as a heat source is selected. a $1.0m^3$ water tank with a 6kW electronic heater is installed and a water temperature and pressure is maintain constantly also thermometer is injected. Two of gas meter, one of pressure regulator and three of time measurement devices are installed in a combustion facility and fuelling facility with a magnet valve so it can observe and record combustion reactions. Quantity of hot water that heated by boiler is recorded using a quantity measurement tank, and have been heated by the boiler have been to record and measure the amount and utilized the data acquired through measurement of all factors that are applied to acquire hot water in order to calculate the use rate of final energy. In conclusion, this researcher drew the economic strong points of the hot water generated by gas.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.9
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• pp.783-788
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• 2008

We suggest a CNT-based gas sensor for breath alcohol measurement. The sensor was composed of single-walled carbon nanotubes (SWCNTs) thin film on flexible PES (polyethersulfone) substrate, and the SWCNTs thin film was formed by multiple spray-coating with SWCNTs solution which was well-dispersed, highly controlled and functionalized in ethanol solvent. In this work, three types of SWCNTs thin films were deposited with changes in the number of spray-coatings to 20, 40 and 60 times in order to compare electrical response properties of the SWCNTs thin films. from the fabricated sensors, conductance and capacitance responses were measured and discussed. Alcohol gas sensors have been commercialized widely as gauge for breath alcohol measurement which is applicable to checking whether car drivers are drinking-driving or not. Our alcohol gas sensors showed good sensitivity and linearity even at room temperature.

• Journal of Power System Engineering
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• v.15 no.4
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• pp.19-24
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• 2011

The operational efficiency of domestic gas turbine is about 25% and it is now in the trend of the gradual growth in spite of the severe temperature, frequent starting and shutdown according to the environmental management and the energy-efficient use. Rotor bolts of gas turbine in power plants have been the cause of defects because these gas turbines have been operated for a long time under the high pressure and temperature environment experiencing the aging change and stress concentration of the bonded part. The connection parts of the bolt revealed various failure shape and these parts were elongated under very low pressure when operated in the relaxed condition. The cause is in the lack of the metal distribution in the bottle lack area and the cap screw of the bolt is broken totally in case that the nut is fastened in most cases. Gas turbine rotor bolts are connected to the rotor wheel and these bolts caused the vibration, the bulk accident of the rotor in the event that the coupling power among these bolts was relaxed. Therefore, we would like to evaluate the soundness of the main part of the gas turbine rotor bolt through the measurement of the inner condition change along with the mechanic deterioration and temperature, stress in the gas turbine rotor material.

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.107-107
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• 1999

Direct-contact condensation experiments of atmospheric steam and steam/air mixture on subcooled water flowing co-currently in a rectangular channel are carried out uszng an infrared thermal camera system to develop a temperature measurement method. The inframetrics Model 760 Infrared Thermal Imaging Radiometer is used for the measurement of the temperature field of the water film for various flow conditions. The local heat transfer coefficient is calculated using the bulk temperature gradient along the (low direction. It is also found that the temperature profiles can be used to understand the interfacial condensation heat transfer characteristics according to the flow conditions such as noncondensable gas effects, inclination effect, and flow rates.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.220-220
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• 2011

The Ne-Xe plasmas in dense plasma-focus device with coaxial electrodes were generated for extreme ultraviolet (EUV) lithography. The influence of gas mixture ratio, Ne-Xe (1, 10, 15, 20, 25, 30, 50%) mixture gas, on EUV emission measurement, EUV intensity and electron temperature in the coaxially focused plasma were investigated. An input voltage of 4.5 kV was applied to the capacitor bank of 1.53mF and the diode chamber was filled with Ne-Xe mixture gas at a prescribed pressure. The inner surface of the cylindrical cathode was lined by an acetal insulator. The anode was made of tin metal. The EUV emission signal of the wavelength in the range of 6~16 nm has been detected by a photo-detector (AXUV-100 Zr/C, IRD). The visible emission line was also detected by the composite-grating spectrometer of the working wavelength range of 200~1100 nm (HR 4000CG). The electron temperature is obtained by the optical emission spectroscopy (OES) and measured by the Boltzmann plot with the assumption of local thermodynamic equilibrium (LTE).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.11
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• pp.1496-1502
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• 2002

An Altitude Engine Test Facility(AETF) was built at the Korea Aerospace Research Institute in October 1999 and has been being operated for altitude testing of gas turbine engines of 3,000 Ibf class or less. The AETF has been calibrated using several engines such as J69 of Teledyne Co. as a facility checkout engine. Uncertainty analyses on the air flow rate and thrust were performed using the test results, according to ASME PTC 19.1-1998. Several modifications on the facility and test method were made in order to improve the measurement uncertainty to a satisfactory level over the whole operating envelop. Spatial distributions of pressure and temperature were measured, sensors were substituted by more accurate ones, inlet duct was modified to refine the flow quality, and pressure control logic was revised to remove the cell pressure fluctuation. As a result, the uncertainty of the air flow measurement was improved by 0.1% over all the test conditions, and the net thrust measurement by up to 3%. The improved measurement uncertainties of air flow and thrust are 0.68～O.73% and 0.4～1.3%, respectively.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.8
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• pp.74-81
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• 2019

Cars are inspected in the transport sector for their ability to achieve the greenhouse gas reduction targets. A vehicle (automobile) inspection broadly consists of regular and total checks, and both the safety level and the amount of exhaust gas are checked simultaneously during a vehicle inspection. This study deals with the efficiency of a soot probe to measure soot emissions from diesel vehicles. When the vehicle exhaust gas measurement is performed, there may be a difference between the exhaust gas temperature and the soot suction amount because of the different shape and angle of the exhaust port for each vehicle type. This may result in some incidents where the correct inspection nonconforming vehicle is not selected. Therefore, in this study, the shape of the probe was improved to increase the soot measurement efficiency under the condition of the exhaust pipe angle change.