• Journal of Periodontal and Implant Science
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• v.28 no.2
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• pp.235-247
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• 1998

Calcium sulfate has a long history of medical use as an implant material. The biocompatibiliry of the material has been clearly established. Bone ingrowth concomitant with resorption occurs rapidly with efficient conduction of bone from particle to particle. Calcium sulfate also has a potential for functioning as a good bamer membrane. The purpose of this study was to compare the biocompatibility of different types of calcium sulfate grafting materials including an expelimental calcium sulfate compound on periodontal ligament cells in vitro as a preliminary test towards the development of a more convenient and useful form of grafting material which could promote regeneration of periodontal tissue. Human periodontal ligament cells were collected from the premolar teeth extracted for orthodontic treatment. cells were cultured in a.MEM culture medium containing 20% FBS, at $37^{\circ}C$ and 100% humidity, in a 5% CO2 incubator. Cells were cultured into 96 well culture plate $1{\times}104$ cells per well with $\alpha$-MEM and incubated for 24 hours. After discarding the medium, those cells were cultured in $\alpha$-MEM contained with 10% FBS alone (control group), in medcal-grade calcium sulfate(MGCS group), in plaster(plaster group), experimental calcium sulfate paste(CS paste group) for 1, 2, 3 day respectively. And then each group was characterized by examining of the cell counting, MTI assay, collagen synthesis. The results \vere as follows. 1. In the analysis of cell proliferation by cell counting, both medical-grdde calcium sulfate group and plaster group showed no stastically significant difference at day 1, 2, 3 accept for plaster group at day 1 compared to control group, but there was stastically significant difference between CS paste group and all other groups at day 1, 2, 3(P<0.05). 2. In the analysis of cytotoxicity by MIT assay, both medical-grade calcium sJlfate group and plaster group showed no stastically significant difference compared to control group at day 1, 2, 3 but there was stastically significant difference between CS paste group and all other groups at day 1, 2, 3(P<0.OS). 3. In the analysis of collagen synthesis by immunoblotting assay, high level was detected for medical-grade calcium sulfate group and plaster group at day 1, 2, 3 compared to CS paste group. On the basis of these results, medical-grade calcium sulfate and plaster was shown to possess biocompatibility whereas the CS paste had unfavourable outcome. This observation shows a need for modification of the materials contained in calcium sulfate paste.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.5 no.1
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• pp.104-118
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• 1995

This study was performed to evaluate factors affecting desorption of organic solvents collected on charcoal tube and to find out the optimum condition. Desorption efficiency for polar analytes was improved when several polar desorption solvents such as methanol, dimethylformamide(DMF), 2-(2-butoxyethoxy)ethanol were added to carbon disulfide($CS_2$). The best improvement was achieved when 10% dimethylformamide(DMF) in $CS_2$ was used as desorption solvent. During storage of polar analytes, recovery was greatly reduced. Especially, the recovery of cyclohexanone was decreased to 18.1 % after a month storage at $34^{\circ}C$. After two weeks storage, recovery of polar analytes was sharply decreased. Water adsorbed on charcoal interfered the recovery of polar analytes but didn't interfere that one of nonpolar solvent, toluene. When 10% DMF in $CS_2$ was used as desorption solvent, the effect of water on recovery was decreased, comparing with Desorption efficiency increased when analyte loading increased, and usage of 10% DMF in $CS_2$ decreased the loading effect. Increasing volume of desorption solvent was not effective to improve desorption efficiency of analytes when 10% DMF was used. Continuous shaking and sonication is not helpful to increase the desorption efficiency of analytes except cyclohexanone using 10% DMF. When silica gel used as adsorbent, methanol was better desorbent than dimethylsulfoxide. Analytes adsorbed on silica gel showed high recovery in low concentration and less affected by humidity. On the basis of this study, the following conclusions have been drawn. To improve the recovery of polar organic materials in air samples, it is necessary to analyze samples as soon as possible after they were collected. Otherwise, samples must be stored at low temperature. Using two components of desorption solvents, such as 10% DMF in $CS_2$, the effects of loading and humidity decreased for polar analytes such as methyl ethyl ketone and methyl isobutyl ketone. When work place has high humidity with low concentration of polar organic solvents, silica gel can be used as adsorbent, because it produces quantitative recovery for polar analytes at this condition. But it should be noted that high humidity makes breakthrough easy in silica gel samples.

• Journal of Convergence for Information Technology
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• v.10 no.8
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• pp.223-228
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• 2020

Objective of this study was to compared the amount of bacteria in the toothbrush according to the management method of the toothbrush in use and the acidity of intraoral bacteria. Toothbrushes in use in more than one month of 50 healthy adults were collected and the number of bacteria and pH of the toothbrushes were measured. When the number of brushings per day was 4, the pH 4.97 and the microbial numbers was the lowest at 42.16(104×CFU/ml). When the replacement period of the toothbrush was 1 month, the pH 5.35 and the microbial numbers was the lowest at 19.80(104×CFU/ml). When stored in the bathroom, the pH 4.78, and the microbial numbers was highest at 149.46(104×CFU/ml). As a result, in order to block the germs of the toothbrush, it is necessary to develop a method that can easily disinfect the contaminated toothbrush at home. In addition, I think that it is necessary to educate about the proper brush cleaning and storage method when teaching brushing.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.2
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• pp.95-104
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• 2005

Effects of the aluminum melting temperature, melting time and a kind of flux agents on the distribution of surrogate nuclide were investigated in the electric furnace at the aluminum melting including surrogate radionuclides(Co, Cs, Sr) in order to establish the fundamental research of the melting technology for the metallic wastes from the decommissioning of the TRIGA research reactor. It was verified that the fluidity of aluminum melt was increased by adding flux agent but it was slightly varied according to the sort of flux agents. The results of the XRD analysis showed that the surrogate nuclides move into the slag phase and then they were combined with aluminum oxide to form more stable compound. The weight of the slag generated from aluminum melting test increased with increasing melting temperature and melting time and the increase rate of the slag depended on the kind of flux agents added in the aluminum waste. The concentration of the cobalt in the ingot phase decreased with increasing reaction temperature but it increased in the slag phase up to 90$\%$according to the experimental conditions. The volatile nuclides such as Cs and Sr considerably transferred from the ingot phase to the slag and dust phase.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.1
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• pp.57-62
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• 2008

No matter how small amount of heavy metals it may be cause skin allergies through percutaneous adsorption when existing in cosmetic products as impurities. In order to develop a highly sensitive method for simultaneous determination of $Pb^{2+},\;Fe^{2+},\;Cu^{2+},\;Ni^{2+},\;Zn^{2+},\;Co^{2+},\;Cd^{2+},\;and\;Mn^{2+}$ in coloring agents and cosmetic products with rapidity and accuracy, we carried out the determination on ion chromatography. All of these metals are well separated through a bifunctional ion-exchange column(IonPac CS5A) and detected by post-column reaction and spectrophotometric detection. The calibration graphs are linear($r^2>0.999$) in the range $0.1{\sim}1000{\mu}g/mL$. Detection limits for 200 ${\mu}L$ of sample solution are at the level of ${\mu}g/L$, which is sufficient for judging whether the product is safe or not. The relative standard deviations(RSDs) of the retention time and the peak area are less than 0.21 and 1.24%, respectively. The recovery rates are $97{\sim}104%$. The new method was applied to analyze the amount of heavy metals which were contained in 22 cosmetic products and 11 coloring agents.

• The korean journal of orthodontics
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• v.51 no.2
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• pp.95-104
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• 2021

Objective: To evaluate the trueness and precision of full-arch scans acquired using five intraoral scanners and investigate the factors associated with the dimensional accuracy of the intraoral scan data. Methods: Nine adult participants (mean age, 34.3 ± 8.3 years) were recruited. Four zirconium spheres (Ø 6 mm) were bonded to the canines and the molars. Following acquisition of reference scans using an industrial-grade scanner, five intraoral scanners, namely i500, CS3600, Trios 3, iTero, and CEREC Omnicam, were used to scan the arches. Linear distances between the four reference spheres were automatically calculated, and linear mixed model analysis was performed to compare the trueness and precision of the intraoral scan data among the different scanners. Results: The absolute mean trueness and precision values for all intraoral scanners were 76.6 ± 79.3 and 56.6 ± 52.4 ㎛, respectively. The type of scanner and the measured linear distances had significant effects on the accuracy of the intraoral scan data. With regard to trueness, errors in the intermolar dimension and the distance from the canine to the contralateral molar were greater with Omnicam than with the other scanners. With regard to precision, the error in the linear distance from the canine to the molar in the same quadrant was greater with Omnicam and CS3600 than with the other scanners. Conclusions: The dimensional accuracy of intraoral scan data may differ significantly according to the type of scanner, with the amount of error in terms of trueness being clinically significant.

• Journal of Convergence for Information Technology
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• v.10 no.4
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• pp.104-114
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• 2020

We investigated the best antibiotics using blending oils after screening 11 kinds of essential oil known as antibiotics from plants. The minimum inhibitory concentration (MIC) and the minimum killing concentration (MBC) were found to be essential for essential oils B and E to inhibit target bacteria. All gram-positive bacteria containing S. aureus used in this experiment were shown highly antibiotic activity. And only A. baumanii in gram-positive bacteria and C. albicans in fungi were shown highly antibiotic activity. The essential oils used in our experiments showed better antibiotic activity compared to major studies using natural antibiotics with excellent antibiotic activity and essential oils from natural medicine. It is not known what mechanism of antimicrobial activity the essential oil used in the test has, but it is interpreted as a synthetic inhibitory mechanism of cell wall compared with other previous studies. From these results, it is expected that some substances or functional products with antibiotic activity will be developed.

• Journal of Convergence for Information Technology
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• v.9 no.12
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• pp.104-114
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• 2019

This study was to find factors affecting on recognition and performance of peripheral intravenous infusion management among pediatric nurses. In analysis using SPSS/Win 24.0, the average scores of recognition and performance were 3.34±0.39, 3.42±0.37 out of 4 each. 'Maintenance and exchange' and 'education' were the lowest each among subdomains. There're significant differences in recognition and performance according to working departments et. al.(p=.039, p<.001), and there's a positive correlation between recognition and performance(r=.591, p<.001). Factors affecting on recognition were performance(β=.57) and working department(β=.22), and on performance were recognition(β=.57) and educated experience(β=.19). And explanation rate were 41.2%, 41.4% each in stepwise multiple regression. In conclusion, recognition and performance were mutually influencing factors. Therefore, it is needed to increase performance by preparing measures to improve recognition of peripheral intravenous infusion management.

• Journal of Convergence for Information Technology
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• v.11 no.5
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• pp.104-110
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• 2021

This study was conducted to confirm the change in the contents of the ingredients according to the extraction method of nipa palm. The contents were analyzed by extraction according to the ethanol ratio, extraction time, and extraction temperature. The contents of polyphenols and flavonoids according to the ratio of the extraction solvent were the highest at 36.91 and 27.62 mg/g, respectively, when extracted with 50% ethanol. Polyphenols and flavonoids according to extraction temperature and extraction time showed the highest content of 40.83 and 37.63 mg/g, respectively, when extracted for 6 hours at 60℃. The contents of the major component of nipa palm according to the ethanol ratio were 2.08 mg/g in 70% ethanol for 5-O-caffeoylshikimic acid, 0.10 mg/g for 4-hydroxybenzoic acid in 30% ethanol, and 0.12 mg/g for 3,4- hydroxybenzoic acid in 50% ethanol. It is expected that it can be used as basic research data when developing natural materials such as food and cosmetics through the change in the contents of the ingredients contained in nipa palm according to the extraction methods.

• Journal of Convergence for Information Technology
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• v.11 no.7
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• pp.104-110
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• 2021

A novel selective oxidation process has been developed for low source/drain (S/D) series resistance of the fin channel metal oxide semiconductor field effect transistor (MOSFET). Using this technique, the selective oxidation fin-channel MOSFET (SoxFET) has the gate-all-around structure and gradually enhanced S/D extension regions. The SoxFET demonstrated over 70% reduction in S/D series resistance compared to the control device. Moreover, it was found that the SoxFET behaved better in performance, not only a higher drive current but also higher transconductances with suppressing subthreshold swing and drain induced barrier lowering (DIBL) characteristics, than the control device. The saturation current, threshold voltage, peak linear transconductance, peak saturation transconductance, subthreshold swing, and DIBL for the fabricated SoxFET are 305 ㎂/㎛, 0.33 V, 13.5 𝜇S, 76.4 𝜇S, 78 mV/dec, and 62 mV/V, respectively.