• Journal of Korean Society of Water and Wastewater
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• v.11 no.1
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• pp.81-87
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• 1997

Coagulation is very important process in water works. The subsequent processes are directly affected by this process. Many factors such as turbidity, alkalinity, pH, hardness, total organic carbon(TOC), velocity gradient and flocculation time effect on coagulation process. Among these factors, specially TOC is being concerned target substance to be removed due to trihalomenthanes(THMs) precursor and alkalinity is being one of the major parameter for removing TOC. We have researched the consumption of coagulant with TOC alkalinity concentration of water and removal efficiency of residual TOC and turbidity with alkalinity. Furthermore we have investigated particle size distributions with velocity gradient and alkalinity. The consumption of coagulant was proportionally increased to TOC and alkalinity concentration and the removal of TOC in Nakdong river water was very difficult more than 150 mg/l in alkalinity but large morecular weight organic such as humic acid could be removed easily. Coagulation of low alkalinity water was more rapidly occured than of high alkalinity water by analyzing the particle size distributions. High alkalinity water needed higher mixing energy for a good coagulation within limited flocculation time.

• Applied Microscopy
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• v.42 no.3
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• pp.136-141
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• 2012

Diversification and individualization are pursued to fulfill the increasing human desire for beauty. There are many methods to change human appearances; of these, a permanent wave is often applied to improve beauty. A permanent wave uses physical and chemical methods to break and reform the bonds of natural hair. Thus, research into the optimized conditions for permanent waves is necessary to minimize hair damage and improve the efficiency of the treatment. The object of this study is to examine the effect of varying the alkalinity (8%, 12%, and 16%) of the permanent wave treatment on the wave efficiency, degree of hair damage via tensile strength, and degree of hair protein release. The results indicate that the treatment with the highest alkalinity (16%) is more effective than that with 8% alkalinity; however, the degree of hair damage when treated with the 16% alkalinity wave is higher than with the 8% alkalinity wave. Additionally, hair proteins increasingly dissolve with increasing alkalinity of the permanent wave.

• Journal of Soil and Groundwater Environment
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• v.24 no.1
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• pp.10-16
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• 2019

Alkalinity is an essential parameter for understanding geochemical processes and calculating partial pressure of $CO_2$, dissolved inorganic carbon, and mineral saturation indices. The Gran Titration Method (GTM) is one of the most accurate methods for measuring the alkalinity in water samples. However, this method has not been widely employed in measuring groundwater alkalinity in Korea, probably due to inadequate and insufficient understanding of the method. In this regard, this article was prepared to introduce GTM and related know-hows learned from the authors' experiences in measuring alkalinity. This paper also introduces a MS Excel-based alkalinity calculator as a handy tool for GTM.

• Journal of Korean Society on Water Environment
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• v.30 no.1
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• pp.25-30
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• 2014

This study is done to prove the premise that both alkalinity and hardness affect on the dissolved phosphorus concentration so that the growth of algae is also affected in water bodies like rivers and lakes. Statistical analysis of the water quality data of 13 reservoirs collected for the last decade shows the relations between alkalinity and chlorophyll-${\alpha}$ and between hardness and chlorophyll-${\alpha}$ are not linear but follow second order equation. This relation seems to be due to two antagonistic effects accompanying a simultaneous increase in alkalinity and hardness. The increase stimulates the growth of algae by supplying carbonates and $Ca^{2+}$ to algae and at same time it causes a decrease in soluble phosphorus which retards algae to grow. These opposing tendencies are confirmed by theoretical calculations with the MINTEQ model. There seems to be ranges of alkalinity and hardness that are in favor of algae growth; the ranges are less than 44 mg/L as $CaCO_3$ in alkalinity and also less than 63 mg/L as $CaCO_3$ in hardness. This finding will provide a solid base to develop an effective water quality management of water bodies.

• Journal of the Korea Concrete Institute
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• v.16 no.4 s.82
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• pp.549-555
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• 2004

Cement of three alkalinities (equivalent alkalinities of 0.36,0.52 and 0.97) was employed in fabricating a set of classical G109 type specimens. To-date, these have been subjected to a one week wet-one week dry cyclic pending using 15 w/o NaCl solution. At the end of the dry period, potential and macro-cell current were measured to indicate whether the top reinforcing steel was in the passive or active state. Once this bar became active, the specimen was autopsied and the extent of corrosion was documented. Subsequent to visual inspection, concrete powder samples were collected from the upper region of the top rebar trace; and at a certain times concrete cores were taken from non-reinforced specimens. Using these, determinations were made of (1) critical chloride concentration for corrosion initiation ($Cl_{th}^-$), (2) effective chloride diffusion coefficient ($D_e$), and (3) pore water alkalinity ($[OH^-]$). The pore water alkalinity was strongly related to the alkali content of cement that was used in the mix. The chloride concentration, ($Cl^-$), was greater at active than at passive sites, presumably as a consequence of electro migration and accumulation of these species at active site subsequent to corrosion initiation. Accordingly, ($Cl^-$) at passive sites was considered indicative of the threshold concentration fur corrosion initiation. The $Cl_{th}^-$ was increased with increasing Time-to-corrosion ($T_i$). Consequently, the HA(High Alkalinity) specimens exhibited the highest $Cl_{th}^-$ and the NA(Normal Alkalinity) was the least. This range exceeds what has previously been reported in North America. In addition, the effective diffusion coefficient, $D_e$, was about 40 percent lower for concrete prepared with the HA cement compared to the NA and LA(Low Alkalinity) ones.

• Journal of Soil and Groundwater Environment
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• v.14 no.3
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• pp.1-13
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• 2009

Alkalinity and total carbon contents were measured by acid neutralizing titration (ANT), back titration (BT), gravitational weighing (GW), non-dispersive infrared-total carbon (NDIR-TC) methods for assessing precision and accuracy of alkalinity and total carbon concentration in $CO_2$-rich water. Artificial $CO_2$-rich water(ACW: pH 6.3, alkalinity 68.8 meq/L, $HCO_3^-$ 2,235 mg/L) was used for comparing the measurements. When alkalinity measured in 0 hr, percent errors of all measurement were 0~12% and coefficient of variation were less than 4%. As the result of post-hoc analysis after repeated measure analysis of variance (RM-AMOVA), the differences between the pair of methods were not significant (within confidence level of 95%), which indicates that the alkalinity measured by any method could be accurate and precise when it measured just in time of sampling. In addition, alkalinity measured by ANT and NDIR-TC were not change after 24 and 48 hours open to atmosphere, which can be explained by conservative nature of alkalinity although $CO_2$ degas from ACW. On the other hand, alkalinity measured by BT and GW increased after 24 and 48 hours open to atmosphere, which was caused by relatively high concentration of measured total carbon and increasing pH. The comparison between geochemical modeling of $CO_2$ degassing and observed data showed that pH of observed ACW was higher than calculated pH. This can be happen when degassed $CO_2$ does not come out from the solution and/or exist in solution as $CO_{2(g)}$ bubble. In that case, $CO_{2(g)}$ bubble doesn't affect the pH and alkalinity. Thus alkalinity measured by ANT and NDIR-TC could not detect the $CO_2$ bubble although measured alkalinity was similar to the calculated alkalinity. Moreover, total carbon measured by ANT and NDIR-TC could be underestimated. Consequently, it is necessary to compare the alkalinity and total carbon data from various kind of methods and interpret very carefully. This study provide technical information of measurement of dissolve $CO_2$ from $CO_2$-rich water which could be natural analogue of geologic sequestration of $CO_2$.

• Journal of Sericultural and Entomological Science
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• v.15 no.2
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• pp.45-53
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• 1973

1. The sericin solubility increased rapidly as the increase of water M-alkalinity. 2. The acidity of the treated water was nutralized at the over 25ppm of M-alkalinity. 3. The more M-alkalinity of the sample water is, the more M-alkalinity was found after cocoon treat. 4. The total hardness of sample water seemed to be droped as M-alkalinity increased. 5. The sericin solubility also seemed to be droped as the increase of water acidity. 6. In case of treat finish with cocoon, the acidity and total hardness seemed to increase as the acidity of the water increased, but M-alkalinity was nutralized at 20~40 ppm of water acidity or the M-alkalinity could not be found in case over 40ppm of acidity. 7. In case increase of iron component with sample water, sericin solubility seemed to drop down, and mangan component showed the same nature but dull drop. 8. After cocoon was treated with water, acidity, M-alkalinity and total hardness were increased by the extraction from cocoon shell because of pH and treating temperature but not because of iron componnent. Mangan component, however, affected as to increase of acidity and total hardness but to decrease for M-alkalinity. 9. In case change of M-alkalinity and total hardness, sericin solubility has increased also. 10. In case constant pH and total hardness, the more M-alkalinity is, the more sericin solubility was found. 11. In case constant pH, total hardness, and M-alkalinity, the more acidity is, the less sericin solubility was found. 12. In case constant pH(6.8) and M-alkalinity, the more total hardness is, the less sericin solubility was found. 13. Though the combination of water, high solubility water, medium solubility water and low solubility water were prepared. The high solubility water desolved sericin 2.2% more than low solubility water. And the medium solubility water desolved sericin as much as 2.4~2.9%. 14. It was found that the most important factors for filature water are pH, M-alkalinity, acidity and total hardness which may need more words for optimum filature water development. 15. In case of repeat use of water, the buffer action of water has increased so that the sericin solubility to be decreased.

• Corrosion Science and Technology
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• v.3 no.6
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• pp.245-250
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• 2004

A series of classical G109 type concrete specimens was exposed to cyclic wet and dry ponding with 15 w/o NaCl solution for approximately five years. Mix design variables included 1) three cement alkalinities (EqA of 0.97, 0.52, and 0.36) and 2) three water-cement ratios (0.50, 0.41, and 0.37). To determine the corrosion initiation time, corrosion potential and macro-cell current between top and bottom bars were monitored. Subsequent to corrosion initiation, specimens were autopsied and visually inspected. Concrete powder samples were collected from top rebar trace and chloride concentration was measured. Also, time-to-corrosion, $T_i$, for specimens of the individual mix designs was represented using Weibull analysis. Time-to-corrosion was a distributed parameter; and because of this, corrosion initiation of four identical specimens for each mix varied, often over a relatively wide range. Specimens fabricated using the lowest water cement ratio and the highest alkalinity cement exhibited the longest time-to-corrosion initiation and the highest chloride threshold levels. Time-to-corrosion did not increase monotonically with cement alkalinity, however, presumably as a consequence of relatively high $Cl^-$ binding in the lower pore water pH range. The chloride threshold level, $Cl_{th}$, increased with increasing $T_i$ and, consequently, was greatest for the highest cement alkalinity specimens.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.2
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• pp.215-223
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• 2006

The internal corrosion of water distribution systems is the main cause for the problem of the public health threat as well as water leakage in the damaged pipeline, red water, and odor and taste of the tap water. This study was examined the effect of chemicals used for pH and alkalinity control and corrosion inhibitors for producing the optimal corrosion control method. Corrosion study at different pH and alkalinity indicated that these control using alkaline chemicals was effective in corrosion rate, Fe release reduction, but examined to be increased in turbidity and corrosion-by-products(TTHMs) problems. The turbidity was slightly increased, requiring caution in controlling corrosion with $Ca(OH)_2$. At pH 9.0, TTHMs concentration is increased two times corn pared with non-control of pH. Using the pipe which had experienced 28 years of exposure, iron release was decreased with the corrosion inhibitor. Consequently, pH, Alkalinity control method using alkaline chemicals must be complemented by corrosion inhibitor application for efficient corrosion control.

• Advances in concrete construction
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• v.12 no.6
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• pp.507-515
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• 2021

To evaluate the influence of slag on the alkalinity of pore solution and microstructure of concrete, this paper performs a leaching experiment on hardened cement-slag pastes (HCSP) slice specimens with different slag content in purified water. The pH value of pore solution, average porosity, morphology, phase composition and Ca/Si of HCSP specimens in the leaching process are measured by solid-liquid extraction, saturated-dried weighing, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) and X-ray diffraction (XRD). Results shows that the addition of slag can mitigate an increase in porosity and a decrease in Ca/Si of HCSP in the leaching process. Besides, an appropriate slag content can improve the microstructure so as to obtain the optimum leaching resistance of HCSP, which can guarantee the suitable alkalinity of pore solution to prevent a premature corrosion of reinforced bar. The optimum slag content is 40% in HCSP with a water-binder ratio of 0.45, and an excessive slag causes a significant decrease in the alkalinity of pore solution, resulting in a loss of protection on reinforced bar in HCSP.