• Restorative Dentistry and Endodontics
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• v.27 no.2
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• pp.158-174
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• 2002

The aim of this study was to investigate the effect of light irradiation modes on polymerization shrinkage, degree of cure and microleakage of a composite resin. VIP$^{TM}$ (Bisco Dental Products, Schaumburg, IL, USA) and Optilux 501$^{TM}$ (Demetron/Kerr, Danbury, CT, USA) were used for curing Filtek$^{TM}$ Z-250 (3M Dental Products, St. Paul., MN, USA) composite resin using following irradiation modes: VIP$^{TM}$ (Bisco) 200mW/$\textrm{cm}^2$ (V2), 400mW/$\textrm{cm}^2$ (V4), 600mW/$\textrm{cm}^2$ (V6), Pulse-delay (200 mW/$\textrm{cm}^2$ 3 seconds, 5 minutes wait, 600mW/$\textrm{cm}^2$ 30seconds, VPD) and Optilux 501$^{TM}$ (Demetron/Kerr) C-mode (OC), R-mode (OR). Linear polymerization shrinkage of the composite specimens were measured using Linometer (R&B, Daejeon, Korea) for 90 seconds for V2, V4, V6, OC, OR groups and for up to 363 seconds for VPD group (n=10, each). Degree of conversion was measured using FTIR spectrometer (IFS 120 HR, Bruker Karlsruhe, Germany) at the bottom surface of 2 mm thick composite specimens V2, Y4, V6, OC groups were measured separately at five irradiation times (5, 10, 20, 40, 60 seconds) and OR, VPD groups were measured in the above mentioned irradiation modes (n=5 each). Microhardness was measured using Digital microhardness tester (FM7, Future-Tech Co., Tokyo, Japan) at the top and bottom surfaces of 2mm thick composite specimens after exposure to the same irradiation modes as the test of degree of conversion(n=3, each). For the microleakage test, class V cavities were prepared on the distal surface of the ninety extracted human third molars. The cavities were restored with one of the following irradiation modes : V2/60 seconds, V4/40 seconds, V6/30 seconds, VPD , OC and OR. Microleakage was assessed by dye penetration along enamel and dentin margins of cavities. Mean polymerization shrinkage, mean degree of conversion and mean microhardness values for all groups at each time were analyzed using one-way ANOVA and Duncan's multiple range test, and using chi-square test far microleakage values. The results were as follows : . Polymerization shrinkage was increased with higher light intensity in groups using VIP$^{TM}$ (Bisco) : the highest with 600mW/$\textrm{cm}^2$, followed by Pulse-delay, 400mW/$\textrm{cm}^2$ and 200mW/$\textrm{cm}^2$ groups, The degree of polymerization shrinkage was higher with Continuous mode than with Ramp mode in groups using Optilux 501$^{TM}$ (Demetron/Kerr). . Degree of conversion and microhardness values were higher with higher light intensity. The final degree of conversion was in the range of 44.7 to 54.98% and the final microhardness value in the range of 34.10 to 56.30. . Microleakage was greater in dentin margin than in enamel margin. Higher light intensity showed more microleakage in dentin margin in groups using VIP$^{TM}$ (Bisco). The microleakage was the lowest with Continuous mode in enamel margin and with Ramp mode in dentin margin when Optilux 501$^{TM}$ (Demetron/Kerr) was used.

• Restorative Dentistry and Endodontics
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• v.31 no.2
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• pp.103-112
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• 2006

This study investigated the hypothesis that the dentin bond strength of self-etching adhesive (SEA) might be improved by applying additional layer of bonding resin that might alleviate the pH difference between the SEA and the restorative composite resin. Two SEAs were used in this study; Experimental SEA (Exp, pH: 1.96) and Adper Prompt (AP, 3M ESPE, USA, pH: 1.0) In the control groups they were applied with two sequential coats In the experimental groups, after applying the forst coat of assigned SEAs, the D/E bonding resin of All-Bond 2 (Bisco Inc., USA, pH: 6.9) was applied as the intermediate adhesive. Z-250 (3M ESPE, USA) composite resin was built-up in order to prepare hourglass-shaped specimens . The microtensile bond strength (MTBS) was measured and the effect of the Intermediate layer on the bond strength was analyzed for each SEA using t-test. The fracture mode of each specimen was inspected using stereomicroscope and Field Emission Scanning Electron Microscope (FE-SEM). When D/E bonding resin was applied as the second coat, MTBS was significantly higher than that of the control groups . The incidence of the failure between the adhesive and the composite or between the adhesive and dentin decreased and that of the failure within the adhesive layer increased. According to the results , applying the bonding resin of neutral pH can increase the bond strength of SEAs by alleviating the difference in acidity between the SEA and restorative composite resin.

• Restorative Dentistry and Endodontics
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• v.32 no.1
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• pp.28-36
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• 2007

The purpose of this study was to compare the effect of exponential curing method with conventional curing and soft start curing method on polymerization shrinkage of composite resins. Three brands of composite resins (Synergy Duo Shade, Z250, Filtek Supreme) and three brands of light curing units (Spectrum 800, Elipar Highlight, Elipar Trilight) were used. 40 seconds curing time was given. The shrinkage was measured using linometer for 90 seconds. The effect of time on polymerization shrinkage was analysed by one-way ANOVA and the effect of curing modes and materials on polymerization shrinkage at the time of 90s were analysed by two-way ANOVA. The shrinkage ratios at the time of 20s to 90s were taken and analysed the same way. The results were as follows : 1. All the groups except Supreme shrank almost within 20s Supreme cured by soft start and exponential curing had no further shrinkage after 30s (p < 0.05). 2. Statistical analysis revealed that polymerization shrinkage varied among materials (p = 0.000) and curing modes (p = 0.003). There was no significant interaction between material and curing mode. 3. The groups cured by exponential curing showed the statistically lower polymerization shrinkage at 90s than the groups cured by conventional curing and soft start curing (p < 0.05). 4. The initial shrinkage ratios of soft start and exponential curing were statistically lower than conventional curing (p < 0.05). From this study, the use of low initial light intensities may reduce the polymerization rate and, as a result, reduce the stress of polymerization shrinkage.

• The Korean Journal of Nuclear Medicine Technology
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• v.26 no.1
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• pp.27-32
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• 2022

Purpose When performing a whole-body bone scan, many patients are experiencing psychological difficulties due to the close distance to the detector. Recently, in the medical field, there is a report that using virtual reality (VR) equipment can give pain relief to pediatric patients with weak concentration or patients receiving severe treatment through a distraction method. Therefore, in this paper, VR equipment was used to provide psychological stability to patients during nuclear medicine tests, and it is intended to evaluate whether it can be used in clinical practice. Materials and Methods As VR equipment, ALLIP Z6 VR (ALLIP, Korea) was used and the experiment was conducted after connecting to a mobile phone. The subjects were 30 patients who underwent whole-body bone examination from September 1, 2021 to September 30, 2021. After intravenous injection of 99mTc-HDP, 3 to 6 hours later, VR equipment was put on and whole body images were obtained. After the test, a survey was conducted, and a Likert scale of 5 points was used for psychological anxiety and satisfaction with VR equipment. Hypothesis verification and reliability of the survey were analyzed using SPSS Statistics 25 (IBM, Corp., Armonk, NY, USA). Results Anxiety about the existing whole-body bone test was 3.03±1.53, whereas that of anxiety after wearing VR equipment was 2.0±1.21, indicating that anxiety decreased to 34%. When regression analysis of the effect of the patient's concentration on VR equipment on anxiety about the test, the B value was 0.750 (P<0.01) and the t value was 6.181 (P<0.01). decreased and showed an influence of 75%. In addition, overall satisfaction with VR equipment was 3.76±1.28, and the intention to reuse was 66%. The Cronbach α value of the reliability coefficient of the questionnaire was 0.901. Conclusion When using VR equipment, patients' attention was dispersed, anxiety was reduced, and psychological stability was found. In the future, as VR equipment technology develops, it is thought that if the equipment can be miniaturized and the resolution of VR content images is increased, it can be used in various clinical settings if it provides more realistic stability to the patient.

• Journal of Korean Dental Hygiene Science
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• v.6 no.2
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• pp.151-160
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• 2023

Background: This study analyzed the differences in practice satisfaction, major, and willingness to work abroad among dental hygiene department students at K University in Gangwon-do based on their participation in international practicums. Methods: A survey was conducted on a total of 215 students through convenience sampling of dental hygiene students, and the final 214 responses were analyzed. General characteristics were examined. Major satisfaction and grades were measured on a 5-point Likert scale. And satisfaction with practice, intention to participate in international practicums, and employment were investigated by papers. Descriptive statistical analysis was performed on general characteristics using SPSS software (version 26.0). Due to the convenience sample, nonparametric analysis was used to determine satisfaction with practice and major according to general characteristics using the Mann-whitney U and Kruskal-wallis test. An independent samples t-test was conducted to determine the difference between practice satisfaction and major satisfaction depending on participation in international practicums, and Fisher's exact test was conducted to determine practice satisfaction, willingness to participate in overseas internships, and employment. Results: Concerning future participation in international clinical practicums, 66.7% of students who had previously participated in overseas training expressed willingness to engage again. 40.9% of those who had not participated showed no intention of participating, and there was a significant difference (p<0.05). Additionally, 76.2% of the participants expressed interest in overseas employment, with this difference also being statistically significant (p<0.05). Conclusion: It was confirmed that students' satisfaction with practice and major increased through participation in international practicums, and that they had a positive intention to work abroad and participate in overseas internship programs in the future.

• Korean Journal of Digital Imaging in Medicine
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• v.15 no.2
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• pp.55-61
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• 2013

The purpose of this study is to evaluate image blurring according to variation of the ETL and propose the clinically appropriate ETL range. SIEMENS MAGNETOM Skyra 3.0T and 20 channel head coil were used for the study. MRI phantom was kept the lines horizontally to three direction(X,Y,Z) of the coil and T1, T2 weighted images that used the fast spin echo technique acquired. The ETL with increase of 10 was applied from 10 to 80. In addition, the ETL with increase of 1 was applied in the interval statistically significant differences occurred. And T1, T2 weighted images that used the conventional spin echo technique acquired to compare image blurring of the images that used the fast spin echo technique. The slope of lattice in the images was measured using Image J 1.47v program to evaluate image blurring. And image blurring was determined by the degree of the slope. The statistical significance of both techniques was evaluated by the Kruskal-Wallis test of the SPSS 17.0v. And the correlation of the ETL and image blurring was evaluated quantitatively by regression analysis. The slope of the T1, T2 weighted images that used fast spin echo technique decreased as contrasted with conventional spin echo technique. In the result of the Kruskal-Wallis test, the T1, T2 weighted images that used fast spin echo technique made a significant difference with conventional spin echo technique. Particularly, in the Tomhane' T2 test, the T1, T2 weighted images made a significant difference from ETL 22 and 31 respectively. In the result of the regression analysis, the R-squared of the T1, T2 weighted images are 0.762 and 0.793. It is difficult to apply the long ETL in the T1 weighted image caused by the short TR and multi-slices study. Therefore, clinical impact according to variation of the ETL is very slight in the T1 weighted images. But the application of the proper ETL is demanded in T2 weighted images using the fast spin echo technique in order to prevent image blurring.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.2
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• pp.127-137
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• 2011

We have developed a wearable device that can convert sensor data into real-time step counts and activity levels. Sensor data on gait were acquired using a triaxial accelerometer. A test was performed according to a test protocol for different walking speeds, e.g., slow walking, walking, fast walking, slow running, running, and fast running. Each test was carried out for 36 min on a treadmill with the participant wearing a portable gas analyzer (K4B2), an Actical device, and the device developed in this study. The signal vector magnitude (SVM) was used to process the X, Y, and Z values output by the triaxial accelerometer into one representative value. In addition, for accurate step-count detection, we used three algorithms: an heuristic algorithm (HA), the adaptive threshold algorithm (ATA), and the adaptive locking period algorithm (ALPA). A regression equation estimating the energy expenditure (EE) was derived by using data from the accelerometer and information on the participants. The recognition rate of our algorithm was 97.34%, and the performance of the activity conversion algorithm was better than that of the Actical device by 1.61%.

• Journal of Fashion Business
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• v.10 no.5
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• pp.58-73
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• 2006

The purpose of this study was to improve of fittness and coverage rate of exporting domestic clothing to China for Chinese Adult Female. For study, It was measured 1381 female women aged between 19 and 50 who resident in Beijing and Shanghai in China. as a sample, 1360 female women was seleted for development of apparel sizing system. As for the method of this study was made of 111 items by indirect measures done during Jun. 23 $\sim$ Aug. 7, 2004. Data analysis were processed by SPSS WIN 10.0 Program was used to for technical statistical analysis, correlation analysis, factor analysis, ANOVA(t-test and F-test), duncan's multiple test. The result was as follows: Chinese Adult women's constitutional components determined by factor analysis, six components could be identified: factor 1:constitutional obesty and width size, factor 2: longistudinal body size, factor 3: shoulder form and size, factor 4: longistudinal upper body size, factor 5: under body size, factor 6: shoulder dropping. According to the Women's Wear Specifications(GB/T 1335.2-1997) by drop, body types of Chinese Adult female was classified into six types, it was Y, A, B, C and Z, D. In order, A type as standard somatotype(49.8%), B type(26.9%), Y type (18.8%), C type(2.9%). Y type had the average height and shoulder, bust girth. They were slimmer in overall terms. A type had a normal obesity and body size in height, shoulder, bust girth. They were average Chinese Women. B type had a smaller then A type. They were more obes and thick waist girth. C type had the highest obesity, the widest shoulder and bust girth, and thick waist girth. The characteristics of each body type following the body type structure factor are Y-type for slender type, A-type for standard type, B-type for slightly large type, and C-type for obese type. For each region, the Beijing area had in the order of A-type, Y-type, B-type and C-type, and the Shanghai area had in the order of A-type, B-type, Y-type and C-type.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.151-160
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• 2020

The purpose of this study was to investigate the moderating mediation effect of resilience, on the relationship between emotional intelligence and self-efficacy in career decision-making of nursing students. The participants were 136 nursing college students in the Jeonbuk region. Data was collected in September 2020 via a structured questionnaire survey. The data was analyzed using the SPSS/23.0 program. The analysis used descriptive statistics, Pearson's correlation coefficient, independent t-test, one-way ANOVA, multiple regression analysis, and Sobel's tests. The results showed that emotional intelligence was a circle activity (F=3.13, p=.047), and motivation to nursing (F=4.16, p=.008). Resilience was a circle activity (F=5.50, p=.005), and nursing major satisfaction (t=2.19, p=.031). Career decision-making self-efficacy showed significant differences in grade (F=3.12, p=.048) and major satisfaction (t=2.36, p=.020). Emotional intelligence and resilience (r=.63, p<.001), emotional intelligence and career decision-making self-efficacy (r=.67, p<.001), resilience and career decision-making self-efficacy (r=.76, p<.001) showed significant static correlation. In emotional intelligence and career decision-making self-efficacy, resilience had a partial mediating effect (Z=6.48, p<.001), and explanatory power was 62.2%. Based on the results of this study, to improve the emotional intelligence and career decision-making self-efficacy of nursing students, it is necessary to develop a personalized and resilience-enhanced education program.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.3
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• pp.311-322
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• 2010

The purpose of this study was to evaluate the bond strengths between IPS e.max Press and four different types of resin cements that often used for esthetic restoration. Disc shaped IPS e.max Press blocks(N=40, diameter: 12mm, thickness: 3mm) were fabricated according to the manufacture's instruction and cleaned with ultrasonic cleaner. They were embedded into an autopolymerizing acrylic resin. Fourty cylinder shaped resin block(Filtek Z350, diameter: 4.5mm, thickness: 3mm) were fabricated using a plastic tube. Each specimens were randomly divided into 4 experimental group and bonded each other using 4 different resin cements(Variolink II(light-cure), Variolink II(dual-cure), Calibra, Super-Bond C&B) according to the manufactures' recommendations. All the specimens were stored in normal saline at $37^{\circ}C$ for 24 hours before test. Universal testing machine at a crosshead speed of 1mm/min was used to evaluate the shear bond strength. The data were statistically analyzed using one-way ANOVA(P<.01). Multiple comparison was done by the Tukey HSD test. The shear bond strength of Super-Bond C&B to e.max was significantly lower than those of Calibra, Variolink II(light-cure), Variolink II(dual-cure) (P<.01). The shear bond strength of Calibra, Variolink II(light-cure), Variolink II(dual-cure) to e.max were not significantly different. The shear bond strengths of light-cure/dual-cure cement were higher than that of self-cure cement.