• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.4
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• pp.111-120
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• 2014

The aim of this study is to develop an integrated urea-SCR catalytic filter system for reducing soot and $NO_X$ emissions simultaneously in diesel engines. In this study, the characteristics of exhaust emissions relative to reactive activation temperature under four kinds of engine loads are experimentally investigated by using a four-cycle, four-cylinder, direct injection type, water-cooled turbo intercooler ECU common-rail diesel engine with the integrated urea-SCR $MnO_2-V_2O_5-WO_3/TiO_2/SiC$ catalytic filter system operating at three kinds of engine speeds. The urea-SCR reactor is used to reduce $NO_X$ emissions, and the catalytic filter system is used to reduce soot emissions. The reactive activation temperature is very important for reacting a reducing agent with exhaust emissions. The reactive activation temperatures in this experiment is applied to 523, 573 and 623 K. The fuel is sprayed by the pilot and main injections at the variable injection timing between BTDC $15^{\circ}$ and ATDC $1^{\circ}$ according to experimental conditions. It is found that the $NO_X$ conversion rate is the highest as 83.9% at the reactive activation temperature of 523 K in all experimental conditions of engine speed and load, and the soot emissions shown by the average reduction rate of approximately 93.3% are almost decreased below 0.6% in all experimental conditions regardless of reactive activation temperatures. Also, the THC and CO emissions by oxidation reaction of Mn, V and Ti are shown in the average reduction rates of 70.3% and 38% regardless of all experimental conditions.

• Clean Technology
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• v.26 no.1
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• pp.7-12
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• 2020

Ti-SBA-15 catalysts doped with lanthanide ions (Ln/Ti-SBA-15) were successfully synthesized using conventional hydrothermal method. In addition, they were characterized by XRD, FT-IR, DRS, BET, and PL. The activity of these materials on the photocatalytic decomposition of methylene blue under ultraviolet light irradiation was also examined. Ti-SBA-15 catalysts doped with various lanthanide ions maintained their mesoporous structure. The pore size and pore volume of Ln/Ti-SBA-15 materials decreased but their surface area increased upon the doping of lanthanide ion. Ln/Ti-SBA-15 materials exhibited the type IV nitrogen isotherm with desorption hysteresis loop type H2, which was characteristic of mesoporous materials. The size of hysteresis increased in the doping of lanthanide ions on Ti-SBA-15 material. There was no absorption in the visible region (> 400 nm) regardless of the doping of lanthanide ions to TiO₂ particles, while the broad bands at 220 nm appeared at the Ln/Ti-SBA-15 samples, indicating the framework incorporation of titanium into SBA-15. 1 mol% Pr/ Ti-SBA-15 catalysts showed the highest photocatalytic activity on the decomposition of methylene blue but the Ti-SBA-15 catalysts doped with Eu, Er, and Nd ions showed lower activity compared to pure Ti-SBA-15 catalyst. The PL peaks appeared at about 410 nm at all catalysts while the excitonic PL signal was proportional to the photocatalytic activity for the decomposition of methylene blue.

• Nano
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• v.13 no.10
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• pp.1850124.1-1850124.12
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• 2018

$TiO_2$ films were deposited from oxygen/titanium tetraisopropoxide (TTIP) plasmas at low temperature by Helicon-PECVD at floating potential ($V_f$) or substrate self-bias of -50 V. The influence of titanium precursor partial pressure on the morphology, nanostructure and optical properties was investigated. Low titanium partial pressure ([TTIP] < 0.013 Pa) was applied by controlling the TTIP flow rate which is introduced by its own vapor pressure, whereas higher titanium partial pressure was formed through increasing the flow rate by using a carrier gas (CG). Then the precursor partial pressures [TTIP+CG] = 0:027 Pa and 0.093 Pa were obtained. At $V_f$, all the films exhibit a columnar structure, but the degree of inhomogeneity is decreased with the precursor partial pressure. Phase transformation from anatase ([TTIP] < 0.013 Pa) to amorphous ([TTIP+CG] = 0:093 Pa) has been evidenced since the $O^+_2$ ion to neutral flux ratio in the plasma was decreased and more carbon contained in the film. However, in the case of -50 V, the related growth rate for different precursor partial pressures is slightly (~15%) decreased. The columnar morphology at [TTIP] < 0.013 Pa has been changed into a granular structure, but still homogeneous columns are observed for [TTIP+CG] = 0:027 Pa and 0.093 Pa. Rutile phase has been generated at [TTIP] < 0:013 Pa. Ellipsometry measurements were performed on the films deposited at -50 V; results show that the precursor addition from low to high levels leads to a decrease in refractive index.

• The korean journal of orthodontics
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• v.52 no.6
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• pp.412-419
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• 2022

Objective: This study evaluated the effect of cyclic pre-calcification treatment on the improvement of bioactivity and osseointegration of Ti-6Al-4V mini-screws. Methods: The experimental groups were: an untreated group (UT), an anodized and heat-treated group (AH), and an anodized treatment followed by cyclic pre-calcification treatment group (ASPH). A bioactive material with calcium phosphate was coated on the mini-screws, and its effects on bioactivity and osseointegration were evaluated in in vitro and in vivo tests of following implantation in the rat tibia. Results: As a result of immersing the ASPH group in simulated body fluid for 2 days, protrusions appearing in the initial stage of hydroxyapatite precipitation were observed. On the 3rd day, the protrusions became denser, other protrusions overlapped and grew on it, and the calcium and phosphorus concentrations increased. The removal torque values increased significantly in the following order: UT group (2.08 ± 0.67 N·cm), AH group (4.10 ± 0.72 N·cm), and ASPH group (6.58 ± 0.66 N·cm) with the ASPH group showing the highest value (p < 0.05). In the ASPH group, new bone was observed that was connected to the threads, and it was confirmed that a bony bridge connected to the adjacent bone was formed. Conclusions: In conclusion, it was found that the surface treatment method used in the ASPH group improved the bioactivity and osseointegration of Ti-6Al-4V orthodontic mini-screws.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.893-896
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• 2000

The SrBi$_2$Ta$_2$O$\sub$9/(SBT) thin films are deposited on Pt-coated electrode(Pt/TiO$_2$/SiO$_2$/Si) using RF sputtering method. The SBT thin films deposited on substrate at 400-500[$^{\circ}C$]. SBT thin film deposited on Pt-coated electrodes have the cubic perovskite structure and polycrystalline state. With increasing annealing temperature from 600[$^{\circ}C$] to 850[$^{\circ}C$], flourite Phase was crystalized to 650[$^{\circ}C$] and Bi-layered perovskite phase was crystalized above 700[$^{\circ}C$]. The maximum remanent polarization is 11.73 ${\mu}$C/cm$^2$at 500[$^{\circ}C$] of substrate temperature and 750[$^{\circ}C$] annealing temperature for 30min.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.460-465
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• 2019

In this study, the optimization of active materials and the preparation of particulate adsorbents for the application of metal oxide-based adsorbents for the treatment of $H_2S$, an air pollutant and odorant, occurred in various industrial facilities were investigated. The adsorbents were prepared by using $TiO_2$, which has a high physicochemical stability and relatively high specific surface area among metal oxides and also by different kinds and contents of active materials. The correlation between the physicochemical property and adsorption performance of the adsorbents confirmed that the adsorbent containing KI, which is a typical alkali metal among the active metals, showed the highest adsorption performance. The relationship between the contents and the adsorption performance was non-proportional, but a volcano plot. From XRD, SEM and BET analyses, it was confirmed that the active material was exposed to the surface above a certain amount and also the adsorption performance was the best when the specific surface area and pore volume were $40{\sim}100m^2/g$ and $0.1{\sim}0.3cm^3/g$, respectively. For practical application, the adsorbent was granulated or coated on a ceramic support. It was also confirmed that the adsorbent showed high adsorption performance when the adsorbent was coated on the ceramic rather than that of the granulated support.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.708-715
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• 2017

Recently, in order to meet the stricter emission regulations, the proportion of after-treatments for vehicles and vessels has been increasing gradually. The objective of this study is to investigate the improvement of $CH_4$ reduction ability of natural gas oxidation catalyst (NGOC), which reduces toxic gases emitted from CNG buses. Thirteen NGOCs were prepared, and the conversion performance of noxious gases according to the type of supports, the loading amount of noble metal, and surfactant and aging were determined. Support Zeolite supported on No. 3 $NGOC(1Pt-1Pd-3MgO-3CeO_2/(46TiO_2+23Al_2O_3+23Zeolite)$ is an anionic alkali metal/earth metal component that improved the oxidation reactivity between CO and NO and noble metal dispersion, and thus enhanced the $CH_4$ reduction ability. As the loading amount of Pd, a noble metal with a high selectivity to $CH_4$, was increased, the number of reaction sites was increased and the ability to reduce $CH_4$ was improved. No. 11 $NGOC(1Pt-1Pd-3MgO-3CeO_2/(Z20+Al80)$(pH=8.5), to which nitrate surfactant had been added, exhibited well dispersed catalyst particles with no agglomeration and improved the $CH_4$ reduction ability by 5-15%. The $NGOC(2Pt-2Pd-3Cr-3MgO/90Al_2O_3)$(48h aging), which was mildly thermal aged for 48h, increased the $CH_4$ reduction ability to about 10% or less as compared with No. 12 NGOC(Fresh).

• Journal of the Speleological Society of Korea
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• v.14 no.15
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• pp.42-90
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• 1987

Lee, Moon Won reported by 63 kinds lescribing the petrography and bulk chemical Composition in Petrology of Cheju volcanic island. The total Chemical Composition data was analyzed by the program of FORTRAN77. First, the Conversition equations and the scatter diagram were examined to the analysis, by the least square method. Next, a statistical data requested a mean Value, maximum value, minimum value, the range, the standard deviation, the variance, the Standord Error and the Coefficient of variation. In the standard deviation, a small Composition is MnO and P$_2$O$\sub$5/, a large Composition is SiO$_2$, Mgo and FeO. The Standard error and the variance were the tandency looked like the Standard deviation well. However, the Coefficient Variation differs from the Standard deviation. Where, a large Coefficient of variation are H$_2$O$\^$-/ and H$_2$O$\^$+/, a small Coefficient of variation are Al$_2$O$_3$ and SiO$_2$. The Correlation of Coefficient Can be Calculated numerically from the relation between SiO$_2$, Al$_2$O$_3$ and TiO$_2$ to other Compositions.

• The Journal of the Acoustical Society of Korea
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• v.42 no.1
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• pp.50-56
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• 2023

The hydroxyl radical (·OH) and superoxide anion radical (·O₂^- ) generated by the shock wave generated during ultrasonic cavitation collapse in TiO₂ suspension are highly useful because they can sterilize and disinfect. For practical use as a sterilization method without any chemicals, in this study, we proposed a method for evaluating the generation of radicals generated by high-intensity ultrasound emitted to titanium dioxide suspension. In the proposed method, the sonoluminescence phenomenon, which emits light by ultrasonic cavitation decay energy, was utilized, and the degree of radical generation was evaluated through the amount of light energy by sonoluminescence. As a result, even at a low concentration of titanium dioxide of 0.02 wt%, light energy 5 times higher than in the absence of titanium dioxide was received. After that, as the concentration increased by 0.1 wt%, the luminous intensity of sonoluminescence increased linearly by about 14.8 × 10^-12 lm. Therefore, it was confirmed that the radicals generated by radiating high-intensity ultrasound to the titanium dioxide suspension increased linearly as the concentration of titanium dioxide increased within a given concentration range.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.483-489
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• 2020

Particulate matter is divided into PM10 (particle diameter of 10 ㎛ or less) and PM2.5 (particle diameter of 2.5 ㎛ or less), which are approximately 1/5 of the thickness of the hair. Due to its effect on the human body, lung disease, arteriosclerosis and heart It is known as a carcinogen that causes various diseases such as diseases. It is known that the main cause of such fine dust is nitrogen dioxide (NOx), which is emitted from automobiles in about 57.3% of urban roadsides. Therefore, in this study, as part of the development of functional construction materials to reduce NOx generated from road transport pollutants, comparative evaluation of NOx reduction performance was conducted according to the replacement rate of cement mortar in which cement was replaced with a porous material. In addition, the NOx reduction performance of cement mortar according to the photocatalyst application method and the number of applications was compared an d evaluated. As a result of the experiment, when activated ocher was substituted by 30%, it showed a reduction effect of about 32.7%, showing the best reduction performance.