• Journal of Korean Society of Water and Wastewater
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• v.33 no.2
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• pp.95-101
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• 2019

High voltage impulse(HVI) has been gained attention as an alternate technique controlling $CaCO_3$ scale formation. Investigation of key operational parameters for HVI is important, however, those had not been reported yet. In this study, the effect of temperature and applied voltage of HVI on $Ca^{2+}$ concentration was studied. As the applied voltage from 0 to 15kV and the temperature increased from 20 to $60^{\circ}C$, the $Ca^{2+}$ concentration decreased, indicating that the aqueous $Ca^{2+}$ precipitated to $CaCO_3$. The $Ca^{2+}$ concentration decreased up to 81% under the condition of 15kV and $60^{\circ}C$. Rate constant for the precipitation reaction, k was determined under different temper1ature and voltage. The reaction rate constant under the 15kV and $60^{\circ}C$ condition was evaluated to $66{\times}10^{-3}L/(mmol{\cdot}hr)$, which was 5 times greater than the k of the reaction without HVI at same temperature. The increases in k by HVI at higher temperature region(40 to $60^{\circ}C$) was much greater than at lower temperature region(20 to $40^{\circ}C$), which implies temperature is more important parameter than voltage for reducing $Ca^{2+}$ concentration at high temperature region. These results show that the HVI induction accelerates the precipitation to $CaCO_3$, particularly much faster at higher temperature.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.961-967
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• 1998

In order to improve the optical properties and printability of paper, various fillers are used in papermaking. This study was performed to investigate several fillers-precipitated calcium carbonate(PCC), ground calcium carbonate(GCC), and blends(PCC/talc or micro-talc(MVP) and GCC/talc or micro-talc(MVP)-for their effects on various newsprint properties. Results obtained from the study were summarized as follows ; 1) PCC treatment gave about 16.8% higher retention than GCC treatment at the filler level of 5% and the retention of filler in the handsheet increased as average particle size of mixed filler was increasing($PCC{\leq}GCC<MVP<talc$). 2) PCC treatment kept opacity more highly than no filler treatment and opacity decreased as average particle size of mixed filler was increasing. 3) Independent treatment of PCC kept tear strength more effectively than GeC did, and tear strength increased as average particle size of mixed filler was increasing. 4) Independent treatment of pee kept tensile strength more highly than other treatments and Gee treatment kept tensile strength highly than pee treatment under mixed filler treatment. 5) Burst strength under PCC treatments decreased linearly as average particle size of mixed filler was increasing. 6) Compared "With non-filler treatment, filler treatment gave much better printability.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.1
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• pp.39-45
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• 2014

Various approaches have been tried to reduce the emission of carbon dioxide in paper industry. One of important approaches is to use PCC manufactured from emission gas as a filler. However, it was recognized that PCC is inferior to other fillers in the paper strength properties of view. Therefore, pretreatment of PCC with pulp powder was tried to mitigate the strength reduction of paper. Pretreatment of PCC with pulp powder improved the bulk(7.4~12.9%) and air permeability(24.8~42.98%), but there is no significant change in opacity. Tensile index, burst index and stiffness were decreased by the use of pretreated PCC with pulp powder. Anionic and cationic PAM were used as a additive for PCC pretreatment in order to improve strength properties. There was no significant change in bulk in all kinds of PAM used in this study. Most strength properties were improved by the pretreatment of PCC with the anionic and cationic PAM and pulp powder, although the opacity and stiffness were more or less decreased.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.1
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• pp.41-47
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• 2010

Increasing ash content of the paper is one of the most effective methods for saving raw materials and steam consumption and improving optical properties and better print quality. However, the increase of filler loading or filler content using a conventional wet end system is limited due to severe loss in strength properties, affecting runnability and product quality. This is because the filler has no ability to make bonding with cellulosic fibers. Therefore, if the technology to give filler the bonding ability is developed, the ash content of the paper can be increased more than ever. This study was carried out to modify PCC by coating its surface with starch contributing to better bonding with fibers. To prepare the modified PCC, cationic starch was selected as a polymer and then pretreatment was done by mixing PCC and cationic starch. Consequently, the pretreated PCC contributed to higher tensile strength, stiffness and opacity than the conventional filler, such as GCC and untreated PCC. However, CIE whiteness and ISO brightness decreased slightly compared to conventional fillers.

• The Journal of Internal Korean Medicine
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• v.21 no.1
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• pp.181-184
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• 2000

Dizziness is one of common diseases clinically, it is defined as a hallucination or an illusion of motion that causes sensation disorder of circumstance, and described as circulatory. rotatory leaning. shaking sensation. In particular, benign paroximal positional vertigo(BPPV) is one of peripheral vertigo, it causes dizziness due to debris which has collected within a part of the inner ear. Chemically, debris are small crystals of calcium carbonate. They are derived from structures in the ear called 'otoliths' that have been damaged by head injury, infection, or other disorder of the inner ear, or degenerated because of advanced age. The symptoms of BPPV include dizziness or vertigo, lightheadedness, imbalance, and nausea, Activities which bring on symptoms will vary in each person, but symptom are almost always precipitated by a position change of the head or body. As for treatment of vertigo, it is differentiated as excess in the upper and deficiency in the lower(上實下虛) and treated in oriental medicine and are used to stability. antihistaminics . anticolinergics . vestibule control drug of GABA system in western medicine. Moreover, Dix-hallpike maneuver is applicated in diagnosis and treatment of BPPV patients. A case of dizziness patient suggested benign paroximal positional vertigo who is diagnosed as weakly dizziness(虛暈)showed prominent improvement by Jaeumkunbitang-gamibang(滋陰建脾湯) and Dix-hallpike maneuver.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.2
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• pp.46-55
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• 2013

Recently, there are growing interests on carbon emissions related in climate change which is worldwide emerging important issue. Some research works are now carrying out in order to reduce the carbon emission in pulp and paper industries by the synthesis of precipitated calcium carbonate using the exhaust carbon dioxide from combustion furnace or incinerator. However, for solving the original problems on carbon emission, we need to consider the analysis of basic methodology on $CO_2$ through the process efficiencies. There are two general tools for carbon emissions; one is the greenhouse gas inventory and the other is $LCCO_2$ method which is applied to particular items of raw materials and utilities in unit process. In this study, the carbon emissions in wood-containing printing paper production line were calculated by using $LCCO_2$ method. The general materials and utilities for paper production, such as fibrous materials, chemical additives, electric power, steam, and industrial water were analyzed. As the results, $Na_2SiO_3$ showed the highest loads in carbon emissions, and the total amount of carbon emissions was the highest in electricity. In the production line of printing paper using de-inked pulp and BTMP, as the mixing ratio of DIP was higher, the carbon emissions were decreased because of high use of electric power in TMP process.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.2
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• pp.53-60
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• 2015

The effects of stirring speed during filler modification by dual polymers on flocculation and reflocculation of PCC (precipitated calcium carbonate) particles and its effect on handsheet properties were elucidated. PCC surface was modified by adsorbing A-PAM (anionic polyacrylamide) and C-starch (cationic starch) in series at various stirring speeds. It was found that increasing stirring speed during filler modification decreased the initial floc size of PCC. Continuous stirring with the same speed for filler modification resulted in the decrease of a floc size, eventually reached a steady state. The variations in a floc size was influenced by the stirring speed during filler modification: the lower the stirring speed during filler modification, the larger the floc size variations. Conclusively, the stability of PCC floc could be improved by increasing the stirring speed. In addition, the stirring speed influenced the handsheet properties. The smaller the PCC floc, the lower the strength of handseet. However, too much larger floc size also deteriorated paper strength. There exists an optimum floc size in term of paper strength which shall be controlled by stirring speed during filler modification.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.283-288
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• 2018

Since the crack self-healing materials are activated according to the exposure environmental conditions from the time of crack occurrence, it is very important to clarify the relationship between the healing performance and the exposure environmental conditions of the crack surface. In this paper, the influence of the exposure environmental conditions on the crack healing performance of self-healing repair mortar was investigated through the water permeability test. The influence of temperature and humidity on the crack width of cracked specimens was evaluated. As a result of measuring the change of the crack width, the effect of curing temperature was negligible but it was confirmed that crack-closing occurred due to the change of dry-wet condition. The healing materials produced on the crack surface of the specimens was identified as calcite minerals. Since the minerals with high density are precipitated under the influence of gravity, the healing performance is somewhat different according to the direction of the crack surface, and the healing performance was significantly improved in the wet exposure condition than the air exposure condition.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.5
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• pp.191-198
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• 2022

Zirconia and titanium alloys, which are mainly used for dental implant materials, have poor osseointegration and osteogenesis abilities due to their bioinertness with low bioactivity on surface. In order to improve their surface bioinertness, surface modification with a bioactive material is an easy and simple method. In this study, akermanite (Ca₂MgSi₂O₇), a silicate-based bioceramic material with excellent bone bonding ability, was synthesized by a solid-state reaction and investigated its bioactivity from the analysis of surface dissolution and precipitation of hydroxyapatite particles in SBF solution. Calcium carbonate (CaCO₃), magnesium carbonate (MgCO₃), and silicon dioxide (SiO₂) were used as starting materials. After homogeneous mixing of starting materials by ball milling and the drying of at oven, uniaxial pressing was performed to form a compacted disk, and then heat-treated at high temperature to induce the solid-state reaction to akermanite. Bioactivity of synthesized akermanite disk was evaluated with the reaction temperature from the immersion test in SBF solution. The higher the reaction temperature, the more pronounced the akermanite phase and the less the surface dissolution at particle surface. It resulted that synthesized akermanite particles had high bioactivity on particle surface, but it depended on reacted temperature and phase composition. Moderate dissolution occurred at particle surfaces and observed the new precipitated hydroxyapatite particles in synthetic akermanite with solid-state reaction at 1100℃.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.2
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• pp.107-113
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• 1990

In comparision with calcium sulphate, the effect of calcium-carbonate, -silicate and -hydroxide on desalinization of tidal saline soil was investigated in a continuous leaching column experiments after mixing with an equivalent amount of Ca to sodium plus magnessium in the saline soil. One half of liming materials was mixed to the top one-tenth of column soil and the remainder was spread on the surface. Results obtained are as follows ; 1. Gypsum made easy to percolate and desaline (Na) tidal marine soil but accumulated magnessium in subsoil. 2. $Ca(OH)_2$, $CaCO_3$, and $CaSO_3$ precipitated Mg in the soil which limes were mixed, but they washed down magnessium more severely from the immediate bellow the limed soil and less from the subsequent soil layers. This leaching was more severer at the treatment of $Ca(OH)_2$and lowest at the treatment of $CaSiO_3$. 3. The alkalinity of lime in addition to the dissociation of exchangeable Na raised pH of limed leached tidal soil and slowed down the percolation rate which retarded desalining Na from limed saline soils. This effect was most severe in the $Ca(OH)_2$ treated soil. 4. pH of leached soils was correlated possitively with exchangeable Na and negatively with exchangeable Mg giving follwing relationship pH= 7.77+0.489 Na/Mg r = 0.845.