• Transactions on Electrical and Electronic Materials
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• v.6 no.5
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• pp.229-232
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• 2005

Direct characterization of band alignment at chemical bath deposition $(CBD)-CdS/Cu_{0.93}(In_{1-x}Ga_x)Se_2$ has been carried out by photoemission spectroscopy (PES) and inverse photoemission spectroscopy (IPES). Ar ion beam etching at the condition of the low ion kinetic energy of 400 eV yields a removal of surface contamination as well as successful development of intrinsic feature of each layer and the interfaces. Especially interior regions of the wide gap CIGS layers with a band gap of $1.4\~1.6\;eV$ were successfully exposed. IPES spectra revealed that conduction band offset (CBO) at the interface region over the wide gap CIGS of x = 0.60 and 0.75 was negative, where the conduction band minimum of CdS was lower than that of CIGS. It was also observed that an energy spacing between conduction band minimum (CBM) of CdS layer and valance band maximum (VBM) of $Cu_{0.93}(In_{0.25}Ga_{0.75})Se_2$ layer at interface region was no wider than that of the interface over the $Cu_{0.93}(In_{0.60}Ga_{0.40})Se_2$ layer.

• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.206-214
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• 2005

Heterogeneously-catalyzed oxidation of aqueous phase trichloroethylene (TCE) over supported metal oxides has been conducted to establish an approach to eliminate ppm levels of organic compounds in water. A continuous flow reactor system was designed to effect predominant reaction parameters in determining catalytic activity of the catalysts for wet TCE decomposition as a model reaction. 5 wt.% $CoO_x/TiO_2$ catalyst exhibited a transient period in activity vs. on-stream time behavior, suggesting that the surface structure of the $CoO_x$ might be altered with on-stream hours; regardless, it is probable to be the most promising catalyst. Not only could the bare support be inactive for the wet decomposition reaction at $36^{\circ}C$, but no TCE removal also occurred by the process of adsorption on $TiO_2$ surface. The catalytic activity was independent of all particle sizes used, thereby representing no mass transfer limitation in intraparticle diffusion. Very low TCE conversion appeared for $TiO_2$-supported $NiO_x$ and $CrO_x$ catalysts. Wet oxidation performance of supported Cu and Fe catalysts, obtained through an incipient wetness and ion exchange technique, was dependent primarily on the kinds of the metal oxides, in addition to the acidic solid supports and the preparation routes. 5 wt.% $FeO_x/TiO_2$ catalyst gave no activity in the oxidation reaction at $36^{\circ}C$, while 1.2 wt.% Fe-MFI was active for the wet decomposition depending on time on-stream. The noticeable difference in activity of the both catalysts suggests that the Fe oxidation states involved to catalytic redox cycle during the course of reaction play a significant role in catalyzing the wet decomposition as well as in maintaining the time on-stream activity. Based on the results of different $CoO_x$ loadings and reaction temperatures for the decomposition reaction at $36^{\circ}C$ with $CoO_x/TiO_2$, the catalyst possessed an optimal $CoO_x$ amount at which higher reaction temperatures facilitated the catalytic TCE conversion. Small amounts of the active ingredient could be dissolved by acidic leaching but such a process gave no appreciable activity loss of the $CoO_x$ catalyst.

• Journal of Soil and Groundwater Environment
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• v.10 no.4
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• pp.26-32
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• 2005

Surfactants can be used to enhance the mass transfer rate of hydrophobic compounds into the biologically active liquid phase, resulting in an increase in biodegradation rate of toluene. In this study, the mass transfer rate and the biocompatibility of toluene in the presence of various surfactants were evaluated. Four anionic and non ionic surfactants were tested: sodium dodecyl sulfate (SOS), TritonX-100, Tween 80, and BYK-345 (silicone surfactant). Experimental results showed that BYK-345 at the critical micelle concentration (CMC) enhanced the solubility of toluene. However, there was no increase in the solubility of toluene by SOS and TritonX-100 at their CMCs. With the addition of each surfactant into deionized water the mass transfer rate became faster than that of the case with no surfactant. A bottle study using toluene-degrading microorganisms showed that SOS seriously reduced toluene removal presumably due to the toxicity of the anionic surfactant and/or the substrate competition between the surfactant and toluene. In addition, the degradation rate of toluene was decreased in the presence of BYK-345, indicating that BYK-345 adversely affects the activity of microorganisms. However, TritonX-100 and Tween 80 did not decrease the degradation rate of toluene significantly. Rather, at the low concentration of TritonX-100 toluene degradation rate was even increased. Overall the experimental results suggest that TritonX-100 be the appropriate surfactant for enhanced biological degradation of toluene.

• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.695-699
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• 2021

In this study, Selective Catalytic Reduction on Diesel Particulate Filter (SDPF) after-treatment system was introduced to simultaneously remove NO_x and Particulate Matters (PM) emitted from trucks and special cargo vehicles using old engine. First, in order to select an Selective Catalytic Reduction (SCR) catalyst for SDPF, the de-NO_x performance of V/TiO₂ and Cu-Zeolite catalysts were compared, and the SCR catalyst characteristics were analyzed through Brunauer Emmett Teller (BET), X-ray Diffraction (XRD) and NH3-TPD (Temperature Programmed Desorption). From the activity test results, the Cu-zeolite catalyst showed the best thermal stability. For optimal coating of SDPF, slurry was prepared according to the target particle size. From the coating stability and back pressure test results of SDPF according to the amount of SCR coating, As a result of comparing coating stability, back pressure, and de-NOx performance by producing A, B, and C samples for each loading amount of the SDPF catalyst, the best results were found in the B sample. The engine dynamometer test was conducted for the optimal SDPF after-treatment system, and the test results satisfied Eu-5 regulations.

• Korean Journal of Microbiology
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• v.25 no.4
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• pp.333-338
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• 1987

In order to establish the biological treatment system which can be used for treatment of waste aster from acetaldehyde plant, it was investigated optimum nutrient requirements and growth conditions by mixed culture of Micrococcus roseus AW-6, Micrococcus luteus AW-22, Microbacterium lacticum AW-38 and Microbacterium laevaniformans AW-41 as well as the effect of coagulants and neutralization reagents. Also, it was carried out the continuous culture as well as batch culture to treat the waste water by mixed culture of these strains. The COD removal rate was reached to maximum state for 96hrs culture at pH7.0 and $30^{\circ}C$ NaOH as the neutralization reagents was the most effective, but the coagulants had no effect on the COD remonal rate and the optimum dilution times for treatment were 10 fold. The COD removal rate was also increased by supplimenting 200 ppm $NH_{2}NO_{3}$, 50 ppm $KH_{2}PO_{4}$, 15 ppm $CaCl_{2}$ and 1 ppm $MgSO_{4} \cdot 7H_{2}O $ as additional nutrients. The removal rate coefficient $K_{1}$ on the batch culture was $4.5\times 10^{-6}$, and the detention time for BOD removal rate of 85% was approximately 45hrs. The COD of waste water was reduced to 15% of its initial value by the continuous culture. The COD and BOD of the effluents were to be about 60 ppm and 40 ppm, respectively, and final pH was 7.0.

• Journal of Environmental Science International
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• v.16 no.9
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• pp.1077-1083
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• 2007

[ $V_2O_5/TiO_2$ ] catalyst impregnated ceramic candle filters are in principle, capable of performing shallow-bed dust filtration plus a catalytic reaction, promoted by a catalytic deposited in their inner structure. Pilot-scale $V_2O_5/TiO_2$ catalyst impregnated ceramic candle filters were prepared, characterized and tested for their activity towards the SCR reaction. The effect on NO conversion of operating temperature, gas hourly space velocity, amount of deposited catalyst, pressure drops and long-term experiment (life of catalytic filter) was determined. The following effects of $V_2O_5/TiO_2$ catalyst impregnated ceramic candle filters in SCR reaction are observed: (1) It increases the activity and widens the temperature window for SCR. (2) When the content of $V_2O_5$ catalyst increases further from 3 to 9wt.%, activity of NO increases. (3) NO conversion at first increases with temperature and then decreases at high temperatures (above $400^{\circ} over), possibly due to the occurrence of the ammonia oxidation reaction.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.121-132
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• 2000

This study is to investigate the performance of a new BNR process using predenitrification scheme focusing on nitrogen removal and the possibility of adapting a computer simulation scheme in BNR process development. By using a pre-denitrification basin, higher $COD/NO_3-N$ ratio could be sustained in this BNR process. The results of the investigation showed a SDNR value of 9.04mg/gMv/hr. In the anoxic tank, the average value of SPRR of 6.25mgP/gMv/hr was observed to be very sensitive to SCOD load of influents. By calibrating internal parameters (stoichiometric and kinetic parameters) of the simulation model, the results of simulation for various BNR processes gave good agreement with observed data. The major adjustment was given with three parameters, maximum specific growth rate of heterotrophic biomass, short chain fatty acid (SCFA) limit, and phosphorous release rate. With the series of simulations on varying operational conditions, the simulation by computer program can be a useful tool for process selection, and design and operation of municipal wastewater treatment plant.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.17 no.1
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• pp.279-286
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• 1987

The authors observed a patient who referred to the Department of Oral Radiology, due to diffuse skeletal pain, muscular weakness and unknown tumor mass on the buccal gingiva of upper right molar region. The patient was found to have peripheral reparative giant cell granuloma and osteomalacia. After removal of the tumor, the clinical, radiologic, and laboratory findings of the patient was rapidly normalized with remarkable improvement of bone pain. The results were as follows: 1. After removal of the tumor, the patient improved. the clinical findings such as bone pain, trismus. muscular weakness and he could walk. 2. In postoperative x-ray findings at 1 and 2 months intervals, the lamina dura of all dentition and bony trabeculae in upper and lower arches were regenerating and the bone density increased. 3. In periodic recall check, no occurrence of osteomalacia was existed and the laboratory findings of the patient showed gradual improvement.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.348-348
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• 2010

Behaviors of $TiO_2$-based photocatalysts with different surface structures on the removal of gas-phase toluene with and without UV irradiation are reported. P-25(Degussa) $TiO_2$ powder dispersed in distilled water by sonication was deposited on the transparent glasses and then dried. Some of the samples were further annealed in oven for 1 hr. These samples obtained before and after annealing were characterized by Brunauer- Emmett-Teller (BET), Transmission Electron Microscope (TEM), X-ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared (FT-IR) spectrometry, respectively. Based on BET and TEM data, no significant structural change upon annealing could be identified. However, the sample without annealing showed a significantly higher ability for removing toluene both in the presence and absence of the UV light. XPS and FT-IR results clearly revealed that the population of the OH groups on the surface of $TiO_2$ was higher for the sample without annealing, indicating that the OH groups can enhance the adsorption capacity and photocatalytic activity of $TiO_2$ for the removal of the gas-phase toluene.

• Journal of the Korean Chemical Society
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• v.62 no.5
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• pp.358-363
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• 2018

The purpose of this study is to show the possibility of using Cu catalyst in removal of $NO_x$ from automobile exhaust which is regarded as the primary source of fine dust PM2.5. The energy and the bond lengths of the three possible structures of Cu-NO complex, which is formed by binding NO molecule to Cu, and the changes in IR and Raman spectra are calculated using MPW1PW91 method on the level of 6-311(+)G(d,p) of basis sets with Gaussian 09 program. As a result, the enthalpy of formation of the Cu-NO complexes are obtained as ${\Delta}H=104.89$, 91.98, -127.48 kJ/mol for the linear, bent, and bridging forms of them, respectively. And the bond lengths between N and O in NO complexes, which becomes longer than NO molecule, indicates that O is easily reduced from Cu-NO. In addition, the Cu-NO complexes using Cu catalyst can be easily measured by infrared or Raman spectroscopy because in the IR and Raman spectra of the NO and Cu-NO complexes the positon and the intensity of bands are definitely different in each vibration mode.