• Journal of the Korea Concrete Institute
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• v.11 no.4
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• pp.31-41
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• 1999

Blended Low Heat type cement is ground granulated blast furnace slag and fly ash mixed ternary with ordinary portland cement. From the viewpoint of X-ray patterns of domestic LHC, the main components of cement such as $C_2$S, $C_3$A, $C_3$S are considerably reduced. Therefore the heat evolution of LHC paste is 42cal/g lower than of OPC paste. At early age, the compressive strength development of LHC concrete is delayed, but the slump loss ratio of fresh concrete is reduced more than 20% with elapsed time. The penetrability of LHC is lower than that of OPC by 1/7.8 with the penetrability of chloride ion into the concrete until the age of 120 days. And the PD Index value of LHC is 0.44$\times$10-6 $\textrm{cm}^2$/s, which indicates only 39.3% of OPC. From the Mercury Intrusion Porosimetry test of cement past, we know that the pore size of LHC is more dense than that of OPC by production of C-S-H.

• Korean Journal of Environment and Ecology
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• v.32 no.5
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• pp.486-496
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• 2018

In this study, we have selected Larix kaempferi as a study area in Woraksan National Park for understanding the ion index according to the difference of topography in national parks. We measured the weather and ion at two fixed points, ridge and valley, where the Larix kaempferi dominates in the same ecological structure in Woraksan National Park. The weather measurement results showed the average, maximum, and minimum temperatures of $28.22^{\circ}C$, $29.9^{\circ}C$, and $26.4^{\circ}C$, respectively at the ridge. The average, maximum, and minimum temperatures at the valley were $27.08^{\circ}C$, $27.8^{\circ}C$, and $25.5^{\circ}C$, respectively. The average, maximum, and minimum relatively humidities at the ridge were 67.02%, 75.25%, and 61.95%, respectively. he average, maximum, and minimum relatively humidities at the valley were 69.74%, 76.8%, and 63.75%, respectively. The average, maximum, and minimum amounts of positive ions generated in the ridge was $698.40{\pm}59.80ea/cm^3$, $885.88ea/cm^3$, and $597.88ea/cm^3$, respectively. The average, maximum, and minimum amounts of negative ions generated in the ridge were $736.07{\pm}83.89ea/cm^3$, $934.53ea/cm^3$, and $599.32ea/cm^3$, respectively. The ion index is calculated to be 1.06. The average, maximum, and minimum amounts of positive ions generated in the valley were $1,732.49{\pm}354.08ea/cm^3$, $2,652.10ea/cm^3$, and $1,110.92ea/cm^3$, respectively. The average, maximum, and minimum amounts of negative ions generated in the valley were $1,990.47{\pm}433.57ea/cm^3$, $3,126.75ea/cm^3$, and the minimum value was $1,352.17ea/cm^3$. The ion index is calculated to be 1.16. The difference in the amount of negative ions generated in ridge and valley was $1089.26ea/cm^3$, and the difference of the calculated ion index between the ridge portion and the valley portion was 0.10. The results of this study were provided as the reference weather data of national parks for health management.

• Journal of Environmental Science International
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• v.9 no.4
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• pp.319-323
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• 2000

Nitrate-selective ion exchange resin which have bulky tertiary amine as functional group have been synthesized by the reaction of chloromethylated polystyrene-divinylbenzene copolymer and the corresponding tertiary amine [$NR_3=NE_{t3} 1, N{(C_2 H_4 H_3)}_32]$in ethanol, while commercial resin has $NMe_3$ as functional group. The fundamental properties such as bulk density, water content, appearance index, exchange capacity, effective size, uniformity coefficient of synthesized anion exchange resin (1) have been measured. The ion exchange resin (1) and (2) exhibited the better selectivity for nitrate than sulfate in both batch and continuous column experiments.

• Journal of Environmental Science International
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• v.9 no.6
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• pp.505-509
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• 2000

The purpose of this study was to evaluate the effects of $Ca(OH)_2$ and $CO_2$ additions on the corrosion of metal coupons(ductile iron, galvanized steel, copper and stainless steel). Corrosion rate and released metal ion concentration of ductile iron and galvanized steel decreased by adjusting alkalinity, calcium hardness and pH with $Ca(OH)_2$ & $CO_2$ additions on copper and stainless steel were less than those on ductile iron and galvanized steel. When ductile iron coupon was exposed to water treated with Ca(OH)$_2$&$CO_2$, additions, the main components of corrosion product formed on its surface were $CaCO_3$ and $Fe_2 O_3 or Fe_2 O_4$ which often reduce the corrosion rate by prohibiting oxygen transport to the metal surface.

• Journal of the Korean institute of surface engineering
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• v.34 no.3
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• pp.240-246
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• 2001

The possibility of using a glass block with the composition of sodium borosilicate as starting materials for GRIN glass was examined from the view points of the phase separation of the matrix glass, the effects of leaching and the heating conditions for a porous structure, and the change in the refractive index. Glass specimens with similar compositions were prepared in the form of porous glass using a phase-separation technique. An examination of the heating and leaching conditions and the microstructure dependence of these conditions was made.; Specimens with porous structure were obtained when the heat treatment and leaching conditions were fixed at $540^{\circ}C$ for 30hrs and in a 0.3N$ H_2$$SO_4$ solution at $100^{\circ}C$, respectively. The resultant specimens had some important features on the GRIN glass.; the depth of the gradient and the change in refractive index (Δn) were 4mm and 0.015~0.02, respectively.

• Journal of the Korean Ceramic Society
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• v.37 no.2
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• pp.117-121
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• 2000

Er-doped sodiumborosilicate glass films for waveguides amplifier were fabricated by Aerosol Flame Deposition(AFD) method. Al2O3 was added to sodium borosilicate glass films to suppress the formation of crystalline phase and control the refractive index. the formation of crystalline phase was suppressed above Al2O3 of 6 wt%. As the amount of Al2O3 increased from 2 to 12 wt% the refractive index of glass films increased lineary from 1.4595 up to 1.4710. After the core of 77SiO2-15B2O3-8Na2O＋6 wt%Al2O3＋8wt%Er2O3 was coated on the buffer layer of 77SiO2-15B2O3-8Na2O＋6 wt%Al2O3, the core was etched by reactive ion etching. The absorption spectrum of 3 cm waveguide amplifier showed two peaks of 1530 and 1550 nm.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.1
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• pp.102-107
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• 2019

This paper proposes a method to improve the mass spectral detection performance of the residual gas analyzer. By improving the mode estimation method for setting the threshold value and improving the additive noise elimination method, it is possible to detect mass spectrums having low peak values of the threshold level difficult to distinguish from noise. Ion signal blocks for each mass index with noise removed by the improved method are effective for eliminating invalid ion signals based on the linear and quadratic fittings. The mass spectrum can be obtained from the quadratic fitted curves for the reconstructed ion signal block using only the valid ion signals. In addition, the resolution of the mass spectrum can be improved by correcting the error caused by the shift of the spectral peak position. To verify the performance of the proposed method, computer simulations were performed using real ion signals obtained from the residual gas analysis system under development. The simulation results show that the proposed method is valid.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.918-921
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• 2010

We have proposed an dielectric layer to improve the luminance of red organic light emitting device. Here, we have calculated refractive index of dielectric layer material that was revised refractive index of organic material, ITO and glass. Refractive index of dielectric layer material was 1.711. The structure of dielectric layer was designed in organic material/ITO/dielectric layer/glass. Dielectric material changed thickness that deposited by ion-assisted deposition system. Transmittances of ITO were 95.66-98.85 [%]. Red OLED was fabricated with the structure of TPD($400[{\AA}]$)/DCMII($20[{\AA}]$), Rubrene($20[{\AA}]$)/Alq3($500[{\AA}]$)/LiF($15[{\AA}]$)/Al($1,000[{\AA}]$). Turn-on voltage and Luminance of Red OLED were 10 [V] and 5,857 cd/m2.

• Membrane Journal
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• v.12 no.2
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• pp.55-66
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• 2002

fouling phenomena of ion exchange membranes were reviewed for improved design and operation of electodialysis. The membrane fouling index for electrodialysis (EDMFI) was defined for the quantitative analysis of fouling potential as an analogy to the pressure-driven membrane process. fouling phenomena were compared in the electrodialysis experiments with inorganic foulant (silica sol) and organic foulants (humate and bovine serum albumin (BSA)), and their fouling potentials were analyzed using the fouling index. The comparison showed that the EDMFI could be used as a quantitative measure of the fouling tendency in electrodialysis processes. As a novel fouling mitigation method, square wave power was reported to be effective in electrodialysis with organic foulants. The square wave powers having the pulsed electric field enabled to reduce the membrane fouling significantly at an optimal frequency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.37-39
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• 1994

We have investigated the characteristics of planar optical waveguides formed by silver ion-exchange. Experimental values of the effective indices of guided modes were obtained by measuring the synchronous angles of strongest coupling. Definition of an effective diffusion constant leads to the mode-dispersion curves applicable over a wide range of fabrication conditions. In order to compare experimental and theoretical results, We have plotted each mode index of a wide range of fabrication conditions.