• Journal of the Korean Recycled Construction Resources Institute
• /
• v.7 no.4
• /
• pp.310-315
• /
• 2019

This study conducted a series of studies to find alternative ways to use Chlorine Bypass System-dust(CBS-dust) in cement production. The results of engineering characteristics of CBS-dust are summarized as follows. First of all, the density of CBS-dust is 2.40, lighter than cement and the pH was 12.50 which was strong alkaline. In terms of particle size, it was 11.70 ㎛ which was finer than cement. With chemical properties, calcium oxide(CaO) was the highest as 35.10%, potassium oxide(K₂O) was 32.43%, potassium chloride(KCl) was 19.46%, sulfur oxide(SO₃) was 6.81%, and the remaining chemical components are SiO₂, Fe₂O₃, Al₂O₃, MgO, and the like. Therefore, if CBS-dust is used as early-strength chemical admixtures in the concrete secondary products that use a large amount of mineral admixtures without rebar, it can be an effective method for increasing the strength of concrete as an alkali activator and preventing early-frost damage of Cold Weather Concrete.

• Korean Journal of Materials Research
• /
• v.6 no.8
• /
• pp.833-840
• /
• 1996

Diamond thin films were deposited on p-type (100) Si wafers using MPECVD. Prior to deposition, ultrasonic striking was done to improve density of nucleation sites with dimond powder of 40~$60\mu$m size. Then diamond thin films were deposited at $^900{\circ}C$, 40Torr and 1000W microwave power using ${CH}_{4}$ and ${H}_{2}$ gases. The purity, the morphology and the microstructur'e and microdefects of diamond thin films were characterized by Raman spectroscopy, SEM and TEM, repectively. In Raman spectroscopy the peaks of non-diamond phase increased as ${CH}_{4}$, concentration increased. In SEM, the morphology of diamond thin films varied from crystalline to cauliflower as ${CH}_{4}$, concentration increased. As ${CH}_{4}$ con centration increased, the density of defects increased, with most defects being {III} twin. ${MTP}_{5}$, were formed with five (II]) planes. As these (Ill) Planes were twinned, ${MTP}_{5}$, represented five-fold symmetry. ]n the interfaces, defects in diamond thin films fanned out from small regions implying nucleation sites.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.9
• /
• pp.2396-2401
• /
• 2009

This study is on development of UV-cured hard coating compounds which have more improved abrasion resistance than existing UV-cured urethane-acrylic resin, to prevent a surface of a widely used PVC tile as a constructive material from being scratched. To make a high abrasion resistant hard coating solution compared to UV-cured urethane-acrylic resin which has no abrasion resistance and been used for PVC tiles, we added powder substances of different abrasion resistant level, $Al_2O_3$(Al-160SG-3), $Al(OH)_3$(SH-8W), $SiO_2$(KS-5000), etc., to the resin, changing their contents from 10% to 30% against quantities of resin, and compounded it using Ring-Mill. After coating PVC tiles with the hard coating solution using bar-coating method that can adjust a thickness, we estimated some surface properties-abrasion resistance, pencil hardness, adhesive power, thickness of coating, and so on. As a result, a hard coating solution added 30% $Al_2O_3$ powder to the resin had the finest surface properties-the first grade in abrasion resistance, H in pencil hardness, 100% in adhesive power, and a hard coating solution which showed excellent solidity and abrasion resistance has smaller particle size, higher powder content, and thicker coating thickness.

• Journal of Conservation Science
• /
• v.37 no.6
• /
• pp.778-790
• /
• 2021

The Stone Seated Buddha Triad and Stone Standing Buddha in Bijung-ri are state-designated heritage (treasure) statues having the Buddha style of the Goryeo dynasty from the 6th century. Conservation scientific investigations were conducted to understand the preservation status of these stone Buddha statues and to establish a conservation plan. The Stone Seated Buddha Triad and Stone Standing Buddha are composed of fine-medium grained biotite granite, which is considered to be of the same origin owing to their low magnetic susceptibility distribution of less than 0.2 (×10^-3 SI unit) and similar mineral characteristics. The Stone Seated Buddha Triad has highly homogenous mineral composition and particle size, whole-rock magnetic susceptibility, and geochemical characteristics very similar to those of the nearby outcrop. It was confirmed that a combination of physical, chemical, and biological factors affects the Stone Buddha statues. In particular, both the Stone Seated Buddha Triad and Stone Standing Buddha tend to be chipped off from the front and cracked and scaled from the back. The Stone Standing Buddha located outdoors experiences granularity decomposition and black algae formation, which accelerate the weathering under unfavorable conservation environments. The result of non-destructive physical property diagnosis using ultrasonic velocity showed that both the Stone Seated Buddha Triad and Stone Standing Buddha have been completely weathered (CW), indicating very poor physical properties.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.16 no.5
• /
• pp.217-222
• /
• 2023

The purpose of this paper was to synthesize a polymer organic hard mask that simplifies the manufacturing process, reduces process time significantly, and thereby lowers manufacturing costs. The results of measuring residual metals through vapor refining showed that 9-Naphthalen-1-ylcarbazole(9-NC) measured 101.75ppb in the 4th zone, 2-Naphthol (2-NA) measured 306.98ppb in the 5th zone, and 9-Fluorenone(9-F) measured between 129.05ppb across the 4th and 5th zones. After passing through a filtration system, the synthesized organic hard mask measured residual metals in the range of 9 to 7ppb. Additionally, the thermal analysis indicated a decrease of 2.78%, a molecular weight of 942, carbon content of 89.74%, and a yield of 72.4%. The etching rate was measured at an average of 18.22Å/s, and the coating thickness deviation was averaged at 1.19. For particle sizes below 0.2㎛ in the organic hard mask, no particles were observed. By varying the coating speed at 1,000, 1,500, and 1,800rpm and measuring the resulting coating thickness, the shrinkage rate ranged from 17.9% to 20.8%. The coating results demonstrated excellent adhesion to SiON, and it was evident that the organic hard mask was uniformly applied.

• Journal of Korean Society for Atmospheric Environment
• /
• v.16 no.E
• /
• pp.19-27
• /
• 2000

Particle Induced X-ray Emission (PIXE) and Elemental Analysis Syztem (EAS) were applied to the investiga-tion of the Characteristics and sources of wintertime atmospheric aerosols in Seoul. Atmospheric aerosols were collected by both fine and coarse fractions using a two-stage filter pack sampler from Kon-Kuk university during the winter season of 1999. PIXE was applied to the analysis of the middle and heavy elements with atomic numbers greater than 14(Si) and EAS was applied to the measurement of the light elements such as H, C and N. The fact that 64.2% of mass of fine particles in Seoul consists of the light elements (N, C , and H) suggests that the measurement of light elements is extremely important. The average mass concentration is Seoul was 38.6$\mu\textrm{g}$m(sup)-3. Elements such as Ca, Fe, Mg, and Ti appeared to have very low Fine/Coarse ratios(0.1∼0.4), whereas che-mical components related to anthropogenic sources such as Br, V, Pb, and Zn were observed to accumulate in the fine fraction. In the Asian Dust Storm(ADS) event, the concentation of soil components increased dramatically. Reconstruction of the fine mass concentrations estimated by a newly revised simple model was fairly in good agreement with the measured ones. Source identification was attempted using the enrichment factor and Pearsons coefficient of correlation. The typical elements derived from each source could be classified by this method.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.7 no.3
• /
• pp.428-436
• /
• 1997

Hexacelsian ($BaO{\cdot}Al_2O_3{\cdot}2SiO_2$) powder was prepared by a solution-polymerization route employing PVA solution as a polymeric carrier. A fine amorphous-type hexacelsian powder with an average particle size of 0.8 $\mu \textrm{m}$ and a BET specific surface area of $63 \textrm{m}^2$/g was made by a ball-milling the powder precursor for 12 h after calcination at $800^{\circ}C$ for :1 h. A densified hexacelsian was obtained through sintering at $1550^{\circ}C$ for 2 h under an air atmosphere. The $\alpha\longleftrightarrow\beta$ and $\beta\longleftrightarrow\gamma$ displacive phase transformation in polycrystalline hexacelsia,n was examined by using dilatometry and differential scanning calorimtry. The reconstructive transformation between hexacelsian and celsian was obtained by annealing at $1600^{\circ}C$ for 72h. Volume contraction of 5.6% was accompanied by the reconstructive transformation.

• Transactions of the Korean hydrogen and new energy society
• /
• v.22 no.3
• /
• pp.386-401
• /
• 2011

Mathematical models for various steps in coal gasification reactions were developed and applied to investigate the effects of operation parameters on dynamic behavior of gasification process. Chemical reactions considered in these models were pyrolysis, volatile combustion, water shift reaction, steam-methane reformation, and char gasification. Kinetics of heterogeneous reactions between char and gaseous agents was based on Random pore model. Momentum balance and Stokes' law were used to estimate the residence time of solid particles (char) in an up-flow reactor. The effects of operation parameters on syngas composition, reaction temperature, carbon conversion were verified. Parameters considered here for this purpose were $O_2$-to-coal mass ratio, pressure of reactor, composition of coal, diameter of char particle. On the basis of these parametric studies some quantitative parameter-response relationships were established from both dynamic and steady-state point of view. Without depending on steady state approximation, the present model can describe both transient and long-time limit behavior of the gasification system and accordingly serve as a proto-type dynamic simulator of coal gasification process. Incorporation of heat transfer through heterogenous boundaries, slag formation and steam generation is under progress and additional refinement of mathematical models to reflect the actual design of commercial gasifiers will be made in the near futureK.

• Korean Chemical Engineering Research
• /
• v.50 no.5
• /
• pp.808-814
• /
• 2012

Photocatalytic zinc oxide powders were prepared from precursor zinc acetate and ammonia solution at elevated temperature, $80^{\circ}C$, by hydrothermal precipitation method. The effect of operating parameters, pH of ammonia solution and concentration of zinc acetate solution, on the characteristics of zinc oxide powders were experimentally examined. Zinc oxide powders prepared at the conditions of pH 11, zinc acetate concentration of 1.0 M, precipitation temperature of $80^{\circ}C$, showed smallest average particle diameter of $3{\mu}m$. SEM and XRD analysis confirmed that prepared zinc oxide has hexagonal rods structure, and Anatase type crystallinity. In addition, DRS and PL analysis showed that the zinc oxide has activity at the range of 200~400 nm of UV light. And the zinc oxide decomposed 57% of a food-color stamp Brilliant blue FCF for 3 hours under the UV radiation.

• Applied Chemistry for Engineering
• /
• v.26 no.4
• /
• pp.452-457
• /
• 2015

The physical properties, such as the heat resistance and thermal durability of the temperature difference fatigue resistance should be excellent when preparing an epoxy type resin for a neon transformer housing. In this study, 50 wt% of $SiO_2$ and silica were selected as a reinforcement and diluent filler for epoxy type resins, respectively. Thermal conductivity and thermal stability were measured as the mixing ratio varied upon the particle sizes. The optimal amount of the mixed silica was 50 wt%. Thermal stability was improved with increasing the amount of larger silica particles. The optimal mixing ratio of differently sized silica particles was 28/3 : 14/18 : 8/10 mesh = 1 : 1 : 1. From these results, it is thought that neon transformer is producible which has excellent thermal durability.