• Nuclear Engineering and Technology
• /
• v.41 no.10
• /
• pp.1275-1284
• /
• 2009

A directly heated $SO_3$ decomposer for the sulfur-iodine and hybrid-sulfur processes has been introduced and analyzed using the computational fluid dynamics (CFD) code CFX 11. The use of a directly heated decomposition reactor in conjunction with a very high temperature reactor (VHTR) allows for higher decomposition reactor operating temperatures. However, the high temperatures and strongly corrosive operating conditions associated with $SO_3$ decomposition present challenges for the structural materials of decomposition reactors. In order to resolve these problems, we have designed a directly heated $SO_3$ decomposer using RA330 alloy as a structural material and have performed a CFD analysis of the design based on the finite rate chemistry model. The CFD results show the maximum temperature of the structural material could be maintained sufficiently below 1073 K, which is considered the target temperature for RA 330. The CFD simulations also indicated good performance in terms of $SO_3$ decomposition for the design parameters of the present study.

• Journal of the Korean Professional Engineers Association
• /
• v.14 no.1
• /
• pp.22-29
• /
• 1981

This study concernes the decomposition of cyanide ion in electroplating plant wastewater and COD variation of photodeveloping wastewater under various conditions. Determinations of CN- concentration were carried out by AgNO$_3$ titration method. The sample solutions were pretreated by passing ozone and decompositions were checked as a function of time for ozone treatment. Analysis of film developing wastewater was carried out by KMnO$_4$ method. Electroplating plant wastewater was also examined at various pH; decomposition rate of cyanide ion was found to increase at higher pH. Time required for the decomposition could be shortened by removing the heavy metal ions under alkaline condition. The effect of temperature on decomposition was studied at 40$^{\circ}$ and 60$^{\circ}C$. The result was better at 40$^{\circ}C$ although time for decomposition was almost same at both temperatures. Analysis of film developing wastewater revealed that COD decrease was faster during the first 1 to 2 hours. However, further decrease could not be effected. The existence of unknown special organics resistant to the decomposition was believed to be the reason.

• Journal of the Korean Society of Safety
• /
• v.14 no.1
• /
• pp.73-77
• /
• 1999

In this study, $SO_2$ and $NO_2$ reduction have been investigated by using coil type plasma reactor. The experiments have been carried out changing discharge power, gas flow rate frequency and electrode style to obtain the decomposition rate. Decomposition rates of $SO_2$ and $NO_2$ were obtained 20~98% at gas flow rate 100ml/min~1,000ml/min and discharge power 5~25w respectively. The energy efficiency is very good at the high frequency power. The decomposition rate of $SO_2$ for 5kHz power supply is only 90%, but for 10kHz power supply is very high, more than 98% for 15w. The decomposition rate is increasing according to the residence time or the power consumption of the discharge. About 15W discharge power for 17$cm^2$ reactor is necessary to obtain the decomposition rate of $SO_2$ and $NO_2$ of more than 85% or 98%. From these experiments, the consumption power of the decomposition rate of 98% in 300ppm $NO_2$ gas in nitrogen gas proved to be 18W and 300ppm $SO_2$ gas to be 15w.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.12
• /
• pp.2973-2978
• /
• 2009

The decomposition reaction mechanism of $CH_3CF_2O$ radical formed from hydroflurocarbon, $CH_3CHF_2$ (HFC-152a) in the atmosphere has been investigated using ab-initio quantum mechanical methods. The geometries of the reactant, products and transition states involved in the decomposition pathways have been optimized and characterized at DFT-B3LYP and MP2 levels of theories using 6-311++G(d,p) basis set. Calculations have been carried out to observe the effect of basis sets on the optimized geometries of species involved. Single point energy calculations have been performed at QCISD(T) and CCSD(T) level of theories. Out of the two prominent decomposition channels considered viz., C-C bond scission and F-elimination, C-C bond scission is found to be the dominant path involving a barrier height of 12.3 kcal/mol whereas the F-elimination path involves that of a 28.0 kcal/mol. Using transition-state theory, rate constant for the most dominant decomposition pathway viz., C-C bond scission is calculated at 298 K and found to be 1.3 ${\times}$ 10$^4s{-1}$. Transition states are searched on the potential energy surfaces involving both decomposition channels and each of the transition states are characterized. The existence of transition states on the corresponding potential energy surface are ascertained by performing Intrinsic Reaction Coordinate (IRC) calculation.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.5
• /
• pp.1049-1054
• /
• 2013

In this paper, two-dimensional(2-D) Finite Difference Time Domain(FDTD) method using the domain decomposition method is proposed. We calculated the electromagnetic scattering field of a two dimensional rectangular Perfect Electric Conductor(PEC) structure using the 2-D FDTD method with Schur complement method as a domain decomposition method. Four domain decomposition and eight domain decomposition are applied for the analysis of the proposed structure. To validate the simulation results, the general 2-D FDTD algorithm for the total domain are applied to the same structure and the results show good agreement with the 2-D FDTD using the domain decomposition method.

• Journal of the Korean Applied Science and Technology
• /
• v.27 no.3
• /
• pp.344-352
• /
• 2010

Magnetite and inorganic sludge were mainly composed of $Fe_2O_4$ and $Fe_2O_3$, respectively. Initial specific surface areas of magnetite and inorganic sludge were 130 $m^2$/g and 31.7 $m^2$/g. $CO_2$ decomposition rate for inorganic sludge was increased with temperature. Maximum $CO_2$ decomposition rates were shown 89% for magnetite at $350^{\circ}C$ and 84% for inorganic sludge at $500^{\circ}C$. Specific surface area for magnetite was not varied significantly after $CO_2$ decomposition. However, specific surface area for inorganic sludge was greatly decreased from initial 130 $m^2$/g to approximately 50~60 $m^2$/g after reaction. Therefore, it was estimated that magnetite could be used for $CO_2$decomposition for a long time and inorganic sludge should be wasted after $CO_2$ decomposition reaction.

• Korean Journal of Remote Sensing
• /
• v.26 no.1
• /
• pp.1-7
• /
• 2010

This paper proposes a new decomposition technique for polarimetric synthetic aperture radar (SAR) images. This new decomposition technique is based on the degree of polarization (DoP) and co-polarized phase-difference (CPD) of the measured polarimetric backscattering coefficients. This decomposition technique is compared with the existing three- and four-component decomposition techniques with the ALOS PALSAR full polarimetric L-band data acquired in 2009. It is shown that the new decomposition technique is better or comparable to the existing techniques for the study areas such as sea, bare soil, forest, and urban area.

• Journal of the Society of Naval Architects of Korea
• /
• v.53 no.6
• /
• pp.482-493
• /
• 2016

The identification of modal damping of a segmented hull model with torsional response is difficult task due to the coupling of modal response. This is because the 1st and 2nd torsional vibration modes are closely spaced in frequency domain leading to the situation that the modal decomposition is difficult to achieve by simple band-pass filter. Present study applied several different modal decomposition methods to derive the damping ratio of different modes. The modal decomposition methods considered in this study are simple band-pass filter, Hilbert vibration decomposition, Wavelet transform and proper orthogonal decomposition. Coupled free decay signal obtained from the torsional hammering test on a segmented hull model was processed with four different methods and the derived damping ratios were compared with each other. Discussions also have been made on the pros and cons of the different methodologies.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.12
• /
• pp.5955-5977
• /
• 2018

Performance of the interpolation algorithm used in the technique of bi-dimensional empirical mode decomposition directly affects its popularization and application, so that the researchers pay more attention to the algorithm reasonable, accurate and fast. However, it has been a lack of an adaptive interpolation algorithm that is relatively satisfactory for the bi-dimensional empirical mode decomposition (BEMD) and is derived from the image characteristics. In view of this, this paper proposes an image interpolation algorithm based on the particle swarm and fractal. Its procedure includes: to analyze the given image by using the fractal brown function, to pick up the feature quantity from the image, and then to operate the adaptive image interpolation in terms of the obtained feature quantity. All parameters involved in the interpolation process are determined by using the particle swarm optimization algorithm. The presented interpolation algorithm can solve those problems of low efficiency and poor precision in the interpolation operation of bi-dimensional empirical mode decomposition and can also result in accurate and reliable bi-dimensional intrinsic modal functions with higher speed in the decomposition of the image. It lays the foundation for the further popularization and application of the bi-dimensional empirical mode decomposition algorithm.

• Journal of the Korean Society of Safety
• /
• v.15 no.2
• /
• pp.70-77
• /
• 2000

For hazardous air pollutants(HAP) such as NO, $NO_2$ and $SO_2$ decomposition efficiency, power consumption, and applied voltage were investigated by SPCP(Surface induced discharge Plasma Chemical Processing) reactor to obtain optimum process variables and maximum decomposition efficiencies. Decomposition efficiency of HAP with various electric frequencies(5~50 kHz), flow rates(100~1,000 mL/min), initial concentrations(100~1,000 ppm) and additive($CH_4$) were measured and the products were analyzed with FT-IR. Experimental results showed that for the frequency of 10 kHz, the highest decomposition efficiency of 94.3 % for NO, 84.7 % for $NO_2$ and 99 % far $SO_2$ were observed at the power consumptions of 19.8, 20 and 19W, respectively, and that decomposition efficiency decreased with increasing frequency above 20 kHz. And decomposition efficiency per unit power were 5.21 %/W for $SO_2$, 4.76 %/W for NO and 4.24 %/W for $NO_2$ and the highest decomposition efficiency was observed with $SO_2$. Decomposition efficiency was increased with increasing residence times and with decreasing initial concentration of pollutants. When the additive of $CH_4$ was used, decomposition efficiency was increased with increasing $CH_4$ content, and NO, $NO_2$ and $SO_2$ were almost completely decomposed with the efficiency of 99 %, 98 % and 99 %, respectively and therefore $CH_4$ was a good additive material. The optimum power for the maximum decomposition efficiency were 7.5 W for $SO_2$, 9.5 W for NO and 15.5 W for $NO_2$, respectively. Optimum power with the maximum decomposition efficiency were 9.5 W at 1,000 ppm of NO, 7~8 W at 100~500 ppm of NO and 15.5 W at all concentration range of $NO_2$ and 11.5 W at 1,000 ppm, 4.9 W at 500 ppm, 3.7 W at 100~300 ppm of $SO_2$ and power efficiency was best in these case.