• Transactions of the Korean hydrogen and new energy society
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• v.23 no.1
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• pp.1-7
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• 2012

This study was performed to develop a low Pt content catalyst as a catalyst for HI decomposition in S-I process. Bimetallic catalysts added various amounts of Pt on a silica supported Ni catalyst were prepared by impregnation method. HI decomposition was carried out using a fixed bed reactor. As a result, Ni-Pt bimetallic catalyst showed enhanced catalytic activity compared with each monometallic catalyst. Deactivation of Ni-Pt catalyst was not observed while deactivation of Ni monometallic catalyst was rapidly occurred in HI decomposition. The HI conversion of Ni-Pt bimetallic catalyst was increased similar to Pt catalyst with increase of the reaction temperature over a temperature range 573K to 773K. From the TG analysis, it was shown that $NiI_2$ remained on the Ni(5.0)-Pt(0.5)/$SiO_2$ catalyst after the HI decomposition reaction was decomposed below 700K. It seems that small amount of Pt in bimetallic catalyst increase the decomposition of $NiI_2$ generated after the decomposition of HI. Consequently, it was considered that the activity of Ni-Pt bimetallic catalyst was kept during the HI decomposition reaction.

• Journal of the Korean GEO-environmental Society
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• v.13 no.7
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• pp.49-54
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• 2012

This study focuses on the decomposition of pentachlorophenol(PCP) by an electron beam (E-beam) process. To attain this objective, we investigated the reactive species generated from E-beam process during irradiation (reaction time 0.6 s) and G-values of PCP decomposition and effects of pH and $H_2O_2$ as an additive. The effect of pH values was independent on the decomposition of PCP. However, during E-beam irradiation a scavenging effect of added $H_2O_2$ (> 1mM) for the decomposition of PCP was shown, which was supported by the decreased amounts of $Cl^-$ produced by the decomposition of PCP. Meanwhile, oxalic acid and unidentified organic chlorine compounds as by-products were increased by the addition of $H_2O_2$. Thus, in order to enhance the efficiency of PCP decomposition, the E-beam process has to consider a proper concentration of $H_2O_2$ as a well-known source of strong oxidant hydroxyl radical.

• Journal of Korean Society for Quality Management
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• v.39 no.2
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• pp.234-243
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• 2011

Multivariate control charts are widely used to monitor the performance of a multivariate process over time to maintain control of the process. Although existing multivariate control charts provide control limits to monitor the process and detect any extraordinary events, it is a challenge to identify the causes of an out-of-control alarm when the number of process variables is large. Several fault identification methods have been developed to address this issue. However, these methods require a normality assumption of the process data. In the present study, we propose a bootstrapped-based $T^2$ decomposition technique that does not require any distributional assumption. A simulation study was conducted to examine the properties of the proposed fault identification method under various scenarios and compare it with the existing parametric $T^2$ decomposition method. The simulation results showed that the proposed method produced better results than the existing one, especially in nonnormal situations.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.E1
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• pp.13-20
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• 2002

The electrical and chemical properties of the dielectric barrier discharge (DBD) process for the benzene removal were investigated. The benzene removal was initiated with the applied voltage higher than the discharge onset value. The removal efficiency over 95 % was obtained at approximately 1.6 kJ lite $r^{r-1}$ of the electrical energy density. The increase of the inlet concentration decreased the removal efficiency. However, the benzene decomposition rate increased with the inlet concentration . While the increase of the gas retention time enhanced the removal efficiency, the decomposition rate decreased. Identification of the optimum condition between the decomposition rate and the removal efficiency is required for field applications of the DBD process.s.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.932-938
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• 2010

This paper proposed the effective treatment method for organic substances using the barrier discharge plasma process and catalytic chemical reaction followed from ozone decomposition. The decomposition by the plasma process of organic substances such as trichloroethylene, methyl alcohol, acetone, and dichloromethane carried out, and ozone is generated effectively at the same time. By passing through catalysts, ozone easily decomposed and further decomposed organic substances. And, 2-dimensional distribution of ozone using the optical measurement method is performed to identify the catalytic surface chemical reaction. In addition, CO is easily oxidized into $CO_2$ by this chemical reaction, which might be induced oxygen atom radicals formed at the surface of catalyst from ozone decomposition.

• Clean Technology
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• v.24 no.3
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• pp.206-211
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• 2018

Lead molybdate ($PbMoO_4$) were successfully synthesized using a facile surfactant-assisted hydrothermal process and characterized by XRD, Raman, PL, BET and DRS. We also investigated the photocatalytic activity of these materials for the decomposition of Rhodamine B under UV-light irradiation. From XRD and Raman results, well-crystallized $PbMoO_4$ crystals have been successfully synthesized with a facile surfactant-assisted hydrothermal process and had 52-69 nm particle size. The $PbMoO_4$ catalysts prepared at $160^{\circ}C$ showed the highest photocatalytic activity. The PL peak was appeared at about 540 nm at all catalysts and it was also shown that the excitonic PL signal was proportional to the photocatalytic activity for the decomposition of Rhodamine B.

• Nuclear Engineering and Technology
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• v.44 no.1
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• pp.21-32
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• 2012

Fluorinated compounds mainly used in the semiconductor industry are potent greenhouse gases. Recently, thermal plasma gas scrubbers have been gradually replacing conventional burn-wet type gas scrubbers which are based on the combustion of fossil fuels because high conversion efficiency and control of byproduct generation are achievable in chemically reactive high temperature thermal plasma. Chemical equilibrium composition at high temperature and numerical analysis on a complex thermal flow in the thermal plasma decomposition system are used to predict the process of thermal decomposition of fluorinated gas. In order to increase economic feasibility of the thermal plasma decomposition process, increase of thermal efficiency of the plasma torch and enhancement of gas mixing between the thermal plasma jet and waste gas are discussed. In addition, noble thermal plasma systems to be applied in the thermal plasma gas treatment are introduced in the present paper.

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

• Korean Journal of Remote Sensing
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• v.25 no.6
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• pp.547-557
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• 2009

LIDAR (LIght Detection And Ranging) is an active remote sensing technology which provides 3D coordinates of the Earth's surface by performing range measurements from the sensor. Early small footprint LIDAR systems recorded multiple discrete returns from the back-scattered energy. Recent advances in LIDAR hardware now make it possible to record full digital waveforms of the returned energy. LIDAR waveform decomposition involves separating the return waveform into a mixture of components which are then used to characterize the original data. The most common statistical mixture model used for this process is the Gaussian mixture. Waveform decomposition plays an important role in LIDAR waveform processing, since the resulting components are expected to represent reflection surfaces within waveform footprints. Hence the decomposition results ultimately affect the interpretation of LIDAR waveform data. Computational requirements in the waveform decomposition process result from two factors; (1) estimation of the number of components in a mixture and the resulting parameter estimates, which are inter-related and cannot be solved separately, and (2) parameter optimization does not have a closed form solution, and thus needs to be solved iteratively. The current state-of-the-art airborne LIDAR system acquires more than 50,000 waveforms per second, so decomposing the enormous number of waveforms is challenging using traditional single processor architecture. To tackle this issue, four parallel LIDAR waveform decomposition algorithms with different work load balancing schemes - (1) no weighting, (2) a decomposition results-based linear weighting, (3) a decomposition results-based squared weighting, and (4) a decomposition time-based linear weighting - were developed and tested with varying number of processors (8-256). The results were compared in terms of efficiency. Overall, the decomposition time-based linear weighting work load balancing approach yielded the best performance among four approaches.

• Journal of the Korean institute of surface engineering
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• v.46 no.4
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• pp.153-157
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• 2013

The defect like the void or seam is frequently generated in the PCB (Printed Circuit Board) Via-Filling plating inside via hole. The organic additives including the accelerating agent, inhibitor, leveler, and etc. are needed for the copper Via-Filling plating without this defect for the plating bath. However, the decomposition of the organic additive reduces the lifetime of the plating bath during the plating process, or it becomes the factor reducing the reliability of the Via-Filling. In this paper, the interaction of each organic additives and the decomposition of additive were discussed. As to the accelerating agent, the bis (3-sulfopropyl) disulfide (SPS) and leveler the Janus Green B (JGB) and inhibitor used the polyethlylene glycol 8000 (PEG). The research on the interaction of the organic additives and decomposition implemented in the galvanostat method. The additive decomposition time was confirmed in the plating process from 0 Ah/l (AmpereHour/ liter) to 100 Ah/l with the potential change.