• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.1
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• pp.125-138
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• 1997

Along with recent economic prosperity, the consumption of commercially available beverages has increased dramatically. Beverages on the market are replacing tap water and constituting an increasing large proportion of the total daily fluoride intake. If such changes in the source of fluid intake are not taken into consideration, effective fluoride intake would become difficult in the fluoridated area while there would be confusion as to the basis for proper fluoride supplement prescription in the nonfluoridated area. So, dietary consultation is recommended for every pediatric patient. This study was conducted to provide the reference for dietary consultations on the subject of fluoride supplement using 72 beverages on the market. The fluoride content was measured and the fluoride intake from each age groups was calculated using fluoride ion specific electrode and HMDS-microdiffusion technique. 1. The average fluoride concentration of the 72 beverages was $0.23{\pm}0.10ppm$, from 0.0106ppm to 2.2050ppm. 2. Natural fruit juices, diluted fruit juices, carbonated beverages and mixed beverages showed average fluoride concentration of $0.15{\pm}0.66ppm$, $0.09{\pm}0.11ppm$, $0.15{\pm}0.23ppm$, $0.50{\pm}0.66ppm$, respectively. There were significant differrence between diluted friut juice drinks and mixed beverage, and between the carbonated beverages and mixed beverges(p<0.05). 3. Using available data on the daily total consumption of beverages and the relative consumption of beverages on the market according to age, daily fluoride intake for various age groups was calculated. According to the results, 2 to 3 year-old children need 0.13mgF/day, those between 4 and 6 year-old need 0.15mgF/day, and those between 7 and 10 year-old need 0.17mgF/day.

• Restorative Dentistry and Endodontics
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• v.15 no.1
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• pp.88-96
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• 1990

The purpose of this study was to investigate the fluoride release and solubility of glass ionomer cement associated with three pH media. For this study, GC Fuji II discs (20.0mm in diameter ${\times}$ 1.5mm thick) were immersed in pH 4.0 lactic acid, pH 7.0 distilled water and pH 10.0 KOH solutions for 1, 7, 14 and 28 days. The amount of fluoride release from the cement into three pH media were measured by fluoride specific ion electrode and the solubility was measured by weight loss of discs. The results were as follows: 1. The lower was the pH of media, the more was the amount of release of fluoride. 2. The amount of fluoride release was increased with time lapse. 3. After I day, the solubility was the highest, and after 7 days that was the least. 4. The lower was the pH of media, the more was the solubility, but there was no statistical difference in solubility according to the pH change.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.1
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• pp.136-143
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• 2005

The replacement of dental restorations due to secondary caries is a continuing problem in restorative dentistry. The secondary caries can be partly prevented by using fluoride containing dental materials such as glass ionomer cement, which releases and be recharged with fluoride ion acting as a fluoride reservoir. For the purpose of investigating the behaviors of fluoride release and recharge of conventional and high viscosity glass ionomer cements, the experiment was performed on the seven specimens each from 4 kinds of materials ; 1 kind of conventional glass ionomer cement, 2 kinds of high viscosity glass ionomer cements and 1 kind of composite resin. The amount of fluoride release was measured over 7 days with pH/ion meter and fluoride specific electrode. After measuring daily fluoride release, the specimens were recharged with 2% NaF solutions for 4 minutes and measured for 3 days with recharging repeated two consecutive times. The results were as follows : 1. Significantly more fluoride was released at first day after recharge in all materials except Z-100. 2. High viscosity glass ionomer cements released more or nearly equal amount of fluoride after recharge compared with the initial release(P<0.05). 3. The fluoride release after recharge with 2% NaF solution was in order of Fuji IX, Ketac Fil, Ketac Molar, Z-100.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.1
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• pp.61-64
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• 1977

Fluoride analysis using fluoride specific ion electrode has been carried out from sea water samples at 15 stations in the west coast of Korea. The concentration was varied from 0.83 to 1.00 ppm; ratio to chlorinity ranged from 4.60 to $5.48\times10^{-5}$. There was a tendency that the ratio to chlorinity was increased with the depth. In general the concentration was less than that of other seas.

• Journal of the Korean Electrochemical Society
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• v.22 no.4
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• pp.148-154
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• 2019

Vanadium oxide based materials have been studied as novel negative electrode materials in lithium-ion batteries (LIBs) because of their high specific capacity. In this study, potassium metavanadate ($KVO_3$) was synthesized and its electrochemical properties are evaluated as a negative electrode materials. The aqueous solution of $NH_4VO_3$ is mixed with a stoichiometric amount of KOH. The solution is boiled to remove $NH_3$ gas and dried to obtain a precipitate. The obtained $KVO_3$ powders are heat-treated at 300 and $500^{\circ}C$ for 8 h in air. As the heat treatment temperature increases, the initial reversible capacity decreases, but the cycle performance and Coulombic efficiency are improved slightly. On the contrary, the electrochemical performances of the $KVO_3$ electrodes are greatly improved when a polyacrylic acid (PAA) as binder was used instead of polyvinylidene fluoride (PVDF) and a fluoroethylene carbonate (FEC) was used as electrolyte additive. The initial reversible capacity of the $KVO_3$ is 1169 mAh/g and the Coulombic efficiency is improved to 76.3% with moderate cycle performance. The $KVO_3$ has the potential as a novel high-capacity negative electrode materials.

• Composites Research
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• v.35 no.6
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• pp.394-401
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• 2022

Two polymer precursors, polyvinylidene chloride-resin (PVDC-resin) and polyvinylidene fluoride (PVDF), are assembled into the microporous carbon by pyrolysis. Microporous carbon is advantageous as an electrode for supercapacitors that store electric charges through ion adsorption/desorption. The pyrolysis also turns the various heteroatoms of two precursors into functional groups, contributing to the additional charge storage. The analysis of the porous structure and function group during carbonization are important to develop the carbon for energy storage. Here, we analyzed the functional groups of two polymer-derived carbons through X-ray photoelectron spectroscopy. The electrochemical properties of the functional groups were explored in various pH electrolytes. The specific capacitance of two carbons in the acidic electrolyte (1 M H₂SO₄) was improved compared to that in the neutral electrolyte (0.5 M Na₂SO₄) due to the faradaic charge/discharge reaction of the quinone functional group. In particular, the carbon electrode derived from PVDC-resin exhibits a lower capacity than the carbon from PVDF due to the small micropores. In the alkaline electrolyte (6 M KOH), the highest specific capacitance and rate capability were obtained among the three electrolytes for both electrodes based on the facile adsorption of the constituent electrolyte ions (K⁺, OH^-).

• The korean journal of orthodontics
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• v.28 no.3 s.68
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• pp.399-407
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• 1998

In order to resolve enamel demineralization around orthodontic bracket, fluoride-releasing materials, glass ionomer cements and fluoride-containing resin, were introduced in orthodontic department. There were many studies about their fluoride release, but their results were controversial. The purpose of this study was to clarify the pattern and amounts of fluoride release from glass ionomer cements and a fluoride-containing resin during 70 days in vitro. Disc shaped specimens were prepared and immersed in polyethylene tube containing 2ml distilled deionized water. The daily amounts of the fluoride released from each specimens were measured after experiment 1 day, 3 days, 7 days, 14 days, 42 days and 70 days. They were measured by fluoride-specific electrode combined pH/Ion meter. The following results were as follow, 1. Fluorides released from fluoride-containing resin during 1 day were significantly less than those from glass ionomer cements. 2. On experiment 70 days, mean daily amounts of fluoride released from Miracle-$Mix^{\circledR}$were $3.4{\mu}g/cm^2$, those from Fuji GC $II^{\circledR}$ were $2.7{\mu}g/cm^2$, those from $Orthobond^{\circledR}$ were $2.3{\mu}g/cm^2$, those from Fuji GC $LC^{\circledR}$were $1.4{\mu}g/cm^2$ and those from fluoride-containing resin, $Heliomolar^{\circledR}$, were $0.1{\mu}g/cm^2$. 3. There were no significant differences in daily amounts of fluoride released from between self-curing glass ionomer cements and light-curing glass ionomer cements. Amounts of released fluoride varied among commercially available products. 4. In all experimental materials, amounts of released fluoride decreased rapidly until experimental 3 days and then decreased slowly until 14 days and more slowly until 70 days.