• Journal of the korean academy of Pediatric Dentistry
• /
• v.1 no.1
• /
• pp.41-47
• /
• 1974

The dental caries survey of "K" primary school children was performed twice for one year interval and evaluated the transitional trend of dental caries prevalences. The number of children surveyed at the first year, 1973, was 819 boys and 653 girls; and the second year, 1974, was 815 boys and 661 girls aged 6 to 12. Under this survey, the following results were detected: 1. The average df person rate in deciduous teeth was increased by 7.52% in boy, 5.59% in girl and 6.65% of both. 2. The average df Index in deciduous teeth was increased by 0.13 in boy, 0.04 in girl and 0.1 of both. The average dt Index was decreased by 0.59 in boy, 0.64 in girl and 0.61 of both. The average ft Index was increased by 0.73 in boy, 0.68 in girl and 0.71 of both. 3. There showed no significant differences in DMF person rate between 1973 and 1974. 4. The DMFT Index of the permanent teeth was decreased by 0.19 in boy, and increased by 0.22 in girl. There showed no significant differences in both sexes between 1973 and 1974. The average DT Index was decreased by 0.43 in boy, 0.03 in girl and 0.31 of both. The average FT Index was increased by 0.23 in boy; 0.35 in girl and 0.29 of both. The average MT Index showed no significant differences in both sexes between 1973 and 1974.

• Journal of the Korean Chemical Society
• /
• v.32 no.3
• /
• pp.179-185
• /
• 1988

The reaction of VO_2\;^+$ with benzyl alcohol in perchloric acid and aqueous dimethylformamide leads to the formation of $VO^{2+}$ and benzaldehyde. The products, $VO^{2+}$ and benzaldehyde, are identified by infrared spectroscopy and gas chromatography. Kinetic studies on the reaction of VO_2\;^+$ with benzyl alcohol have been carried out using visible spectroscopy. The empirical rate equation can be expressed as $-d[VO_2\;^+]/dt=2\{\\{k_O+k_H[HClO_4]\}\[VO_2\;^+][C_6H_5CH_2OH]$ The rate determining step for the reaction is the process for the formation of $VO^{2+}$ and $C_6H_5CHOH$. The activation parameters are ${\Delta}H^{\neq}=13.32{\pm}1.73\;kcalmol^{-1}$ and ${\Delta}S^{\neq}=-31.02{\pm}0.09\;calmol^{-1}K^{-1}$ for the oxidation of benzyl alcohol in aqueous dimethylformamide.

• Journal of dental hygiene science
• /
• v.14 no.3
• /
• pp.342-348
• /
• 2014

This study was carried out an elementary school located in B-myeon and K-myeon of Gimje. One school (test group) with a school oral health care office and three schools (control group) without school oral health care offices were selected as sample schools. The dental caries prevention effects were compared between third to sixth graders who received benefits of the school continued oral health management program of K health office in Gimje, and first and second graders who did not receive the benefits due to the suspension of the program. The decayed, missing, and filled (DMF) rate, that received the benefits of the program, the test group was 58.9% and the control group was 76.1%, showing significant difference (p<0.05). For the DMF teeth (DMFT) rate, the who received benefits from the program, the test group was 41.1% and the control group was 64.2%, showing significant difference (p<0.01). For the DMFT index, the third to sixth graders that received benefits of the program, the test group was 1.73 and the control group was 3.66 showing significant difference (p<0.001). For the decayed teeth (DT) index, it was 0.72 for the test group and 1.96 for the control group showing significant difference (p<0.001). For the filled teeth index, the test group was 0.63 for the test group and 0.99 for the control group showing significant difference (p<0.05). For the DT rate, the total test group was 57.23% and 64.16% for the control group. For who received benefits from the program, the DT rate was 54.81% for the test group and 60.98% for the control group. The effects of the student continued oral health management program carried out by the oral health office can be confirmed. It is judged that efforts for continuous maintenance and promotion will be necessary to improve the oral health of students.

• Journal of dental hygiene science
• /
• v.5 no.1
• /
• pp.19-24
• /
• 2005

The purpose of this study was to examine the oral health states of elderly people over the age of 65 from the city of Seongnam, including the number of present permanent tooth, dental caries, rate of treatment need, CPITN and use of prosthesis, in a bid to lay the foundation for improving elderly oral health programs. The findings of the study were as follows: 1. The DMF rate of the male senior citizens stood at 98.3 percent, and that of the women numbered 99.0 percent and DMFT index 20.8. 2. The number of present permanent tooth excluded the third molars was 13. 3. Regarding CPITN, $CPITN_1$ was 74.9 percent, and $CPITN_2$ was 56.2 percent. $CPITN_3$ was 8.0 percent. 4. The rate of full denture wearing of the elderly people was 26.1 percent in the upper part and 17.8 percent in the lower part. And their rate of full denture need was 7.4 percent in the upper part and 4.3 percent in the lower part. 5. Establishing an planned abject for Oral health, Seongnam City has reviewed the necessity of development on enhancement of Oral health.

• Journal of Korean society of Dental Hygiene
• /
• v.8 no.4
• /
• pp.115-125
• /
• 2008

The purpose of this study was to examine the relationship between the Dentocult SM and LB scores of students and their DMF rate. The subjects in this study were 134 special school students in south Gyeong-sang province. After they were tested to find out their, they received tooth brushing education and preventive treatment. The test, education and treatment were all conducted from March 17 to April 9, 2008. Their oral state was checked and recorded by using a mirror and explorer, and then the data on oral state were analyzed to their DMFT, DT, FT and MT rates. All the collected data were analyzed with SPSS 15.0 for Windows program, and independent-samples t-test, one-way ANOVA and crosstabs analysis were implemented to see what differences their disability type, gender, Dentocult-SM scores and Dentocult-LB scores made. The findings of the study were as follows: 1. As for connections between disability type and DMFT rate, the students with mental retardation were similar to the other students in that regard. The mentally retarded students had higher DT and FT rates than the other students, and the MT rate of the latter was higher than that of the former. 2. Concerning the relationship of gender to DMFT and DT rates, the girls had larger DMFT and DT rates than the boys, and the FT and MT rates of the boys were higher than those of the girls. 3. As to links between Dentocult SM scores on the tongue and DMFT, the students whose bacteria was mildly activated had the highest DMFT rate, and the students who had a severely activated bacteria had the highest DT and FT rates. Those who had a moderately activated bacteria had the highest MT rate. 4.Regarding the connection of Dentocult SM scores on maxillyright molar to DMFT and DT rates, the students whose bacteria was severely activated had the highest DMFT and DT rates. Those who had no activated bacteria had the largest FT rate, and the students who had a mildly activated bacteria had the highest MT rate. 5.Regarding the connection of Dentocult SM scores on maxillyleft molar to DMFT and DT rates, the students whose bacteria was severely activated had the highest DMFT and DT rates. Those who had no activated bacteria had the largest FT rate, and the students who had a mildly activated bacteria had the largest MT rate. 6. Regarding the connection of Dentocult SM scores on mandibularright molar to DMFT and DT, FT rates, the students whose bacteria was severely activated had the highest DMFT and DT, FT rates. Those who had a moderately activated bacteria had the highest MT rate. 7. Regarding the connection of Dentocult SM scores on mandibularleft molar to DMFT and DT rates, the students whose bacteria was mildly activated had the highest DMFT and DT rates. Those who had no activated bacteria had the largest FT rate, and the students who had a moderately activated bacteria had the highest MT rate. 8. Regarding the connection of Dentocult LB scores to DMFT and DT rates, the students whose bacteria was severely activated had the highest DMFT and DT rates. Those who had no activated bacteria had a moderately FT rate, the students who had a mildly activated bacteria had a mildly MT rate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.388-388
• /
• 2010

In this study, Ferroelectric vinylidene fluoride-trifluoroethylene (VF2-TrFE) copolymer films were directly deposited on degenerated Si (n+, $0.002\;{\Omega}{\cdot}cm$) using by spin coating method. A 1~5 wt% diluted solution of purified vinylidene fluoride-trifluoroethylene (VF2:TrFE = 70:30) in a dimethylformamide (DMF) solvent were prepared and deposited on silicon wafers at a spin rate of 2000 ~ 4000 rpm for 2 ~ 30 seconds. After annealing in a vacuum ambient at 100 ~ $200^{\circ}C$ for 60 min, upper aluminum electrodes were deposited by vacuum evaporation for electrical measurement. X-ray diffraction results showed that the VF2-TrFE films on Si substrates had $\beta$-phase of copolymer structures. The capacitance on highly doped Si wafer showed hysteresis behavior like a butterfly shape and this result indicates clearly that the copolymer films have ferroelectric properties. The typical measured remnant polarization ($P_r$) and coercive filed ($E_c$) values were about $5.7\;{\mu}C/cm^2$ and 710 kV/em, respectively, in an applied electric field of ${\pm}$ 1.5 MV/em. The gate leakage current densities measured at room temperature was less than $7{\times}10^{-7}\; A/cm^2$ under a field of 1 MV/cm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.169-170
• /
• 2006

In this study, ultra thin films of ferroelectric vinylidene fluoride-trifluoroethylene (VF2-TrFE) copolymer were fabricated on degenerated Si (n+, $0.002\;{\Omega}{\cdot}cm$) using by spin coating method. A 1~5 wt% diluted solution of purified vinylidene fluoride-trifluoroethylene (VF2:TrFE=70:30) in a dimethylformamide (DMF) solvent were prepared and deposited on silicon wafers at a spin rate of 2000~5000rpm for 30 seconds. After annealing in a vacuum ambient at $200^{\circ}C$ for 60 min, upper gold electrodes were deposited by vacuum evaporation for electrical measurement. X-ray diffraction results showed that the VF2-TrFE films on Si substrates had $\beta$-phase of copolymer structures. The capacitance on $n^+$-Si(100) wafer showed hysteresis behavior like a butterfly shape and this result indicates clearly that the dielectric films have ferroelectric properties. The typical measured remnant polarization (2Pr) and coercive filed (EC) values measured using a computer controlled a RT-66A standardized ferroelectric test system (Radiant Technologies) were about $0.54\;C/cm^2$ and 172 kV/cm, respectively, in an applied electric field of ${\pm}0.75\;MV/cm$.

• Advances in nano research
• /
• v.10 no.1
• /
• pp.59-69
• /
• 2021

Electrospinning is a cost-effective and versatile method for producing submicron fibers. Although this method is relatively simple, at the theoretical level the interactions between process parameters and their influence on the fiber morphology are not yet fully understood. In this paper, the aim was finding optimal electrospinning parameters in order to obtain the smallest fiber diameter by using Taguchi's methodology. The nanofibers produced by electrospinning a solution of Thermoplastic Polyurethane (TPU) in Dimethylformamide (DMF). Polymer concentration and process parameters were considered as the effective factors. Taguchi's L9 orthogonal design (4 parameters, 3 levels) was applied to the experiential design. Optimal electrospinning conditions were determined using the signal-to-noise (S/N) ratio with Minitab 17 software. The morphology of the nanofibers was studied by a Scanning Electron Microscope (SEM). Thereafter, a tensile tester machine was used to assess mechanical properties of nanofibrous scaffolds. The analysis of DoE experiments showed that TPU concentration was the most significant parameter. An optimum combination to reach smallest diameters was yielded at 12 wt% polymer concentration, 16 kV of the supply voltage, 0.1 ml/h feed rate and 15 cm tip-to-distance. An empirical model was extracted and verified using confirmation test. The average diameter of nanofibers at the optimum conditions was in the range of 242.10 to 257.92 nm at a confidence level 95% which was in close agreement with the predicted value by the Taguchi technique. Also, the mechanical properties increased with decreasing fibers diameter. This study demonstrated Taguchi method was successfully applied to the optimization of electrospinning conditions for TPU nanofibers and the presented scaffold can mimic the structure of Extracellular Matrix (ECM).

• Current Photovoltaic Research
• /
• v.10 no.4
• /
• pp.101-106
• /
• 2022

We prepared a CsPbI₂Br solution using Cesium iodide (CsI), Lead (II) bromide (PbBr₂) and Lead (II) iodide (PbI₂) materials into a polar solvent mixture of N,N-dimethylformamide (DMF) and Dimethyl sulfoxide (DMSO). A simple spin coating technique was used for the fabrication of CsPbI₂Br absorber layer in the solution process. In order to prepare uniform coating of absorber film we adopted a hot-air process in assocation with the spin coating. It was confirmed that the thin film manufactured by the hot-air process had a higher absorption rate than that without it, and the optical band gap was measured 1.93 eV. The thin film of absorber was uniformly prepared and revealed the Black α-Cubic crystal phase as proved through X-ray diffraction analysis. Finally, a perovskite solar cell having an n-i-p structure was manufactured with a CsPbI₂Br perovskite absorption layer. From the solar cell, we obtained a power conversion efficiency (PCE) of 5.97% in a forward measurement.

• Journal of dental hygiene science
• /
• v.12 no.5
• /
• pp.459-468
• /
• 2012

This study surveyed and analyzed on the relationship between obesity and oral health in early child hood and on the oral health realities targeting 90 young children at K Child Care Center where is located in Gangwon-do Province from 10 to 11, June, 2011. As a result, DMF rate accounted for 56.7%. D rate accounted for 42.2%. The young children with the higher age, height in 100~110cm, and weight in 25 kg were indicated to be higher in DF rate than other toddlers. The young children with height in 110~115 cm were indicated to be higher in prevalence of dental caries in deciduous teeth than other young children. It was indicated that the young children in the higher age and weight leads to the higher in DFT index and DFS index. It was indicated that the young children in the more overweight leads to the higher in the index of dental caries in primary teeth, the filling deciduous teeth index, DFT index, DMFS, and DFS index. Accordingly, the child care center needs to systematically perform the oral health education and oral health management for young children, to allow Young children to acquire right food habit, and to pay close attention even to selecting snack.