• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.38-43
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• 1998

It was realized that the nucleation rate in the synthesis of M-ZSM-5 using various alkali cations such as $Li^+$, $Na^+$, $K^+$ and $Cs^+$ at low temperature and atmospheric pressure was decreased in the order of $Na^+>K^+>Li^+>Cs^+$. Unlike conventional synthesis method at high temperature and pressure, the results showed that at low temperature and atmospheric pressure, the higher the nucleation rate is, the larger the crystal size of M-ZSM-5 obtained ; that is, the crystal size in the order of $K^+>Na^+>Cs^+>Li^+$. In addition, it also suggests that regardless of alkali cations to be used, the current synthesis method can produce M-ZSM-5 with BET surface area greater than $300m^2/g$ within 52hrs. of reaction time, in particular greater than $400m^2/g$ within 32hrs, for $Na^+$ cation.

• Journal of the Korean Society of Combustion
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• v.21 no.4
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• pp.39-47
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• 2016

The aims of this research were to investigate combustion characteristics of lab-scale pressurized oxy-fuel combustion(POFC) system. In this study, the reactor, 800 mm long, was equipped with co-axial burner. Low calorific value syngas that is composed of mainly CO and $H_2$ was used as fuel whereas pure oxygen was used as an oxidant. Thermal heat input to the reactor varied from 2.6 kW to 6.1 kW. The reactor pressure also increases from atmospheric up to 15 bar. The results show that as the pressure increase, the temperature of reactor decreases on the whole in all cases. A significant temperature drop was observed especially at the bottom section of the reactor that exist flame. In addition, the flame instability increases as the pressure increases. Furthermore $NO_x$ emissions increases from atmospheric up to 2 bar. However beyond 2 bar, $NO_x$ emission reduces as pressure increases. Lastly $NO_2$ ratio in $NO_x$ also increases as pressure increases.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.372-379
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• 2018

The improvement of $NO_x$ reduction by $Ag/{\gamma}-Al_2O_3$ with a hydrocarbon ($n-C_7H_6$) in the early state was investigated in a packed-bed dielectric barrier discharge plasma reactor. The results revealed that the combination of plasma with the catalyst enhanced $NO_x$ reduction efficiency at low operating temperatures, depending on the temperature and specific input energy. To sum up, the poor performance of the catalytic $NO_x$ reduction at low temperatures in the early stage before reaching thermochemical steady state can be greatly compensated for by using the atmospheric-pressure plasma generated in the catalyst bed.

• Applied Science and Convergence Technology
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• v.26 no.6
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• pp.201-207
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• 2017

An electron-excited temperature ($T_{ex}$) is not determined by the Boltzmann plots only with the spectral data of $4p{\rightarrow}4s$ in an Ar-plasma jet operated with a low frequency of several tens of kHz and the low voltage of a few kV, while $T_{ex}$ can be obtained at least with the presence of a high energy-level transition ($5p{\rightarrow}4s$) in the high-voltage operation of 8 kV. The optical intensities of most spectra that are measured according to the voltage and the measuring position of the plasma column increase or decay exponentially at the same rate as that of the intensity variation; therefore, the excitation temperature is estimated by comparing the relative optical-intensity to that of a high voltage. In the low-voltage range of an Ar-jet operation, the electron-excitation temperature is estimated as being from 0.61 eV to 0.67 eV, and the corresponding radical density of the Ar-4p state is in the order of $10^{10}{\sim}10^{11}cm^{-3}$. The variation of the excitation temperature is almost linear in relation to the operation voltage and the position of the plasma plume, meaning that the variation rates of the electron-excitation temperature are 0.03 eV/kV for the voltage and 0.075 eV/cm along the plasma plume.

• Analytical Science and Technology
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• v.10 no.1
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• pp.18-30
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• 1997

Na, TPA-ZSM-5 with Si / Al mole ratio of about 130 was synthesized at low temperature and atmospheric pressure. These intermediate products were characterized by using XRD, XRF, FT-IR, NMR, and SEM. As a result, intermediate product were different from those that synthesized by autoclave method but spectroscopic characteristics of the final products showed to be in the typical ZSM-5 region. The defect sites were observed in the final product and removed by calcination at $540^{\circ}C$. Na, TPA-ZSM-5, aboveall, was synthesized at this condition within 48hr.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.3
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• pp.588-594
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• 2001

The aim of this paper is to develop the low temperature vacuum dryer, with low initial investments and operating costs, easy operating method and trouble-free operation Usally operations just below atmospheric pressure, as with direct dryers, but some are built for vacuum operation with pressure as low 50 mmHg abs. The lowers the boiling point to $39^{\circ}C$ The experimental data of quantitative analysis for using practically were obtained by the constant drying rate period and reducing drying rate period according to the temperature of hot water which is the experimental parameters of present experiment. As the results, it took about 20 hours for material to reach about 18% of the final moisture content is order to store products for a long time about 450% of the early moisture content at the beginning of drying and maximum drying rate comes to about 0.30 kg/m2hr at about 350% of the moisture content.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2474-2479
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• 2009

This paper presents an atmospheric microplasma-jet device for bio~medical application. The microplasma-jet device consists of four components; a thin Ni anode, porous alumina insulator, a stainless steel cathode and an aluminum case. The anode has 8 holes, and hole diameter and depth are $200 {\mu}m$ and $60 {\mu}m$, respectively. The discharge test was performed in atmospheric pressure using nitrogen gas and AC voltage at the optimum gas flow rate of 4 Vmin. The plasma-jet is ejected stably for the input voltage ranging from 5.5 to $9.5 kV_{p-p}$. The plasma becomes dense as the input voltage increases, which was verified by the hydrophilicity change of PMMA surface treated by the plasma. The temperature increasement of the aluminum film exposed to plasma-jet illustrates that the micro plasma-jet device is feasible for bio-medical application.

• ETRI Journal
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• v.38 no.6
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• pp.1172-1178
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• 2016

The atmospheric meteorology parameters of the earth, such as temperature, pressure, and humidity, strongly influence the propagation of signals in Global Navigation Satellite Systems (GNSSs). The propagation delays associated with GNSS signals can be modeled and explained based on the atmospheric temperature, pressure, and humidity, as well as the locations of the satellites and receivers. In this paper, we propose an optimized and simplified low cost GNSS base weather station that can be used to provide a global estimate of the integrated water vapor value. Our algorithm can be used to measure the zenith tropospheric delay based on the measured propagation delays in the received signals. We also present the results of the data measurements performed at our station located in the Tlemcen region of Algeria.

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.378-383
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• 2001

An out line of the material process with using the atmospheric pressure glow plasma is described as follows : (1) TiO powder coating with SiO$_2$ (2) Surface treatment of Fluorinated polymers and (3) Surface cleaning of electronic circuit board with using splay type.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1869-1873
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• 2008

In this work, to make it possible to generate glow discharge in atmospheric pressure condition with relatively high and wide electric field, micro channel reactor is proposed. Si DRIE and Cr deposition by Ebeam evaporation is used to make channel and bottom electrode layer. Upper electrode is made from ITO glass to visualize discharge within micro channel. Fabricated reactor is verified by generating uniform glow plasma with N2 / He gases each as working fluid. The range of gas electric field to generate glow plasma is from about 200 V/cm and upper limit is not observed in tested condition of up to 150 kV/cm. This data shows that micro channel plasma reactor is more versatile. Indirect estimation of electron temperature in this reactor can be inferred that the electron temperature within glow discharge in micro reactor lies $0{\sim}2eV$. This research demonstrates that the reactor is appropriate in application that needs to maintain low temperature condition during chemical process.