• Journal of dental hygiene science
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• v.15 no.3
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• pp.259-264
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• 2015

For this experiment, specimen was manufactured by injecting polymer and monomer into silicon mold with volume ratio of 2.5:1 based on ISO 20795-2 so that average thickness, width and length of specimen would be maintained as 3.3 mm, 10.0 mm and 65.0 mm, respectively depending on spray on technique. Specimen was divided into 3 groups ($25^{\circ}C$, $40^{\circ}C$, $70^{\circ}C$) depending on polymerization temperature and 10 specimen was manufactured for each group and it was polymerized in water tank of ${\pm}1^{\circ}C$ under the setting condition of polymerization time of 15 minutes and pressure of 3 bar. After keeping specimen in distilled water of $37^{\circ}C$ for over 48 hours before experiment, flexural strength (FS) and elasticity modulus (EM) of specimen being tested by using Intron (3344; Instron; Instron). SPSS ver. 16.0 was used for analysis and post-hoc test of Scheffe was performed after using one-way ANOVA. When comparing mean value of FS of resin for orthodontics, it was represented in the range of 71.500 MPa for $25^{\circ}C$ group, 74.920 MPa for $40^{\circ}C$ group and 76.880 MPa for $70^{\circ}C$ group and difference was shown in the order of $25^{\circ}C$ group <$40^{\circ}C$ group <$70^{\circ}C$ group but such difference was not significant statistically (p=0.052). Result of EM mean value of resin for orthodontics was more polymerization temperature was high, the more was significant difference represented in the order of $25^{\circ}C$ group <$40^{\circ}C$ group <$70^{\circ}C$ group (p<0.039).

• Restorative Dentistry and Endodontics
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• v.26 no.4
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• pp.263-272
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• 2001

The aim of this study was to investigate the influence of four different light curing modes on the marginal leakage of Class V composite resin restoration. Eighty extracted human premolars were used. Wedge-shaped class Y cavities were prepared on the buccal surface of the tooth with high-speed diamond bur without bevel. The cavities were positioned half of the cavity above and half beyond the cemento-enamel junction. The depth, height, and width of the cavity were 2 mm, 3 mm and 2 mm respectively. The specimens were divided into 4 groups of 20 teeth each. All the specimen cavities were treated with Prime & Bond$^{R}$ NT dental adhesive system (Dentsply DeTrey GmbH, Germany) according to the manufacturer's instructions and cured for 10 seconds except group VI which were cured for 3 seconds. All the cavities were restored with resin composite Spectrum$^{TM}$ TPH A2 (Dentsply DeTrey GmbH, Germany) in a bulk. Resin composites were light-cured under 4 different modes. A regular intensity group (600 mW/${cm}^2$, group I) was irradiated for 30 s, a low intensity group (300 mW/${cm}^2$, group II) for 60 s and a ultra-high intensity group (1930 mW/${cm}^2$, group IV) for 3 s. A pulse-delay group (group III) was irradiated with 400 mW/${cm}^2$ for 2 s followed by 800 mW/${cm}^2$ for 10 s after 5 minutes delay. The Spectrum$^{TM}$ 800 (Dentsply DeTrey GmbH, Germany) light-curing units were used for groups I, II and III and Apollo 95E (DMD, U.S.A.) was used for group IV. The composite resin specimens were finished and polished immediately after light curing except group III which were finished and polished during delaying time. Specimens were stored in a physiologic saline solution at 37$^{\circ}C$ for 24 hours. After thermocycling (500$\times$, 5-55$^{\circ}C$), all teeth were covered with nail varnish up to 0.5 mm from the margins of the restorations, immersed in 37$^{\circ}C$, 2% methylene blue solution for 24 hours, and rinsed with tap water for 24 hours. After embedding in clear resin, the specimens were sectioned with a water-cooled diamond saw (Isomet$^{TM}$, Buehler Co., Lake Bluff, IL, U.S.A.) along the longitudinal axis of the tooth so as to pass the center of the restorations. The cut surfaces were examined under a stereomicroscope (SZ-PT Olympus, Japan) at ${\times}$25 magnification, and the images were captured with a CCD camera (GP-KR222, Panasonic, Japan) and stored in a computer with Studio Grabber program. Dye penetration depth at the restoration/dentin and the restoration/enamel interfaces was measured as a rate of the entire depth of the restoration using a software (Scion image, Scion Corp., U.S.A.) The data were analysed statistically using One-way ANOVA and Tukey's method. The results were as follows : 1. Pulse-Delay group did not show any significant difference in dye penetration rate from other groups at enamel and dentin margins (p>0.05) 2. At dentin margin, ultra-high intensity group showed significantly higher dye penetration rate than both regular intensity group and low intensity group (p<0.05). 3. At enamel margin, there were no statistically significant difference among four groups (p>0.05). 4. Dentin margin showed significantly higher dye penetration rate than enamel margin in all groups (p<0.05).

• Restorative Dentistry and Endodontics
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• v.26 no.4
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• pp.332-340
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• 2001

Flowable composite resin has lower filler content, increased flow, and lower modules of elasticity. It is suggested that flowable composite resin can be bonded to the tooth structure intimately and absorb or dissipate the stress. Therefore, it may be advantageous to use flowable composite resin for the base material of class II restoration and for the class V restoraton. The purpose of this study was to evaluate the microleakage and shear bond strength of four flowable composite resins (Aeliteflo, Flow-It, Revolution, Ultraseal XT Plus) compared to Z100 using Scotchbond Multi Purpose dentin bonding system. To evaluate the microleakage, notch-shaped class V cavities were prepared on buccal and lingual surfaces of 80 extracted human premolars and molars on cementum margin. The teeth were randomly divided into non-thermocycling group (group 1) and thermocycling group (group 2) of 40 teeth each. The experimental teeth of each group were randomly divided onto five subgroups of eight samples (sixteen surfaces). The Scotchbond Multi-Purpose and composite resin were applied for each group following the manufacturer's instructions. the teeth of group 2 were thermocycled five hundred times between 5$^{\circ}C$ and 55$^{\circ}C$. The teeth of group 2 were placed in 2% methylene blue dye for 24 hours, then rinsed with tab water. The specimens were embedded in clear resin, and sectioned longitudinally with a diamond saw. The dye penetration on each of the specimen were observed with a stereomicioscope at $\times$20 magnification. To evaluate the shear bond strength, 60 teeth were divided into five groups of twelve teeth each. The experimental teeth were ground horizontally below the dentinoenamel junction, so that no enamel remained. After applying Scotchbond Multi-Purpose on the dentin surface, composite resin was applied in the shape of cylinder. The cylinder was 4mm in diameter and 2mm in thickness. Shear bond strength was measured using Instron with a cross-head speed of 0.5mm/min. After shear bond strength measurement, mode of failure was evaluated with a stereomicroscope at $\times$30 magnification. All data were statistically analyzed by One Way ANOVA and Student-Newman-Keuls method. The correlation between microleakage and shear bond strength was analyzed by linear regression. The results of this study were as follows ; 1. In non-thermocycling group, the leakage value of Z100 was significantly lower than those of flowable composite resins at the enamel and dentin margin, margin, except that Revolution showed the lower leakage value than that of Z100 at the dentin margin (p<0.05). 2. In thermocycling group, the leakage values of Z100 and Ultraseal XT Plus were lower than those of other subgroup at the enamel and dentin margin, except that Flow-It showed the lower leakage value than that of Ultraseal XT Plus at the dentin margin (p<0.05). 3. The leakage value of Z100 and Ultraseal XT Plus in thermocycling group were not higher than that in non-thermocycling group at the enamel margin. The leakage value of Z100 in thermocycling group was not higher than that in non-thermocycling group at the dentin margin (p<0.05). 4. As for the shear bond strength measurement, there were no statistically significant differences among groups (p<0.05). The shear bond strengths given in descending order were as follows: Z100(16.81$\pm$2.98 MPa), Flow-It(14.8$\pm$4.43 MPa), Aeliteflo(14.34$\pm$3.69 MPa), Revolution(13.46$\pm$4.23 MPa), Ultraseal XT Plus(12.83$\pm$3.16 MPa). 5. Failure modes of all specimens were adhesive failures. 6. There was no correlation between microleakage and shear bond strength.

• Restorative Dentistry and Endodontics
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• v.31 no.6
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• pp.477-484
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• 2006

The purposes of this study were to compare the apical terminus width of simulated curved root canal prepared with three NiTi file systems used by undergraduates for evaluation the effects of flute angle and pitch or radial land on reducing screw-in effect and to determine more safe NiTi file system for inexperienced operators. Fifty inexperienced undergraduate students prepared 150 simulated curved root canals in resin blocks with three NiTi file systems ; ProFile$^{(R)}$, Hero Shaper$^{(R)}$, K3$^{TM}$. The electric motor set at a speed of 300 rpm and torque of 30 in a 16 : 1 reduction handpiece was used. The simulated root canal was prepared to ISO #25 sizes with each file system. The scanned images of pre- and post-instrumented canal of resin block were superimposed. To evaluate the screw-in effect of three NiTi file systems, apical terminus width of root canal was measured from superimposed images and statistical analysis was performed. There were significant differences in three NiTi flle systems. ProFile$^{(R)}$ had significantly smaller width than Hero Shaper$^{(R)}$ and K3$^{TM}$"" (P < 0.05), but no significant difference was observed between K3$^{TM}$ and Hero Shaper$^{(R)}$. Under the condition of this study, active file system (Hero SHaper$^{(R)}$, K3$^{TM}$) with variable pitch and helical angle had more screw-in effect than passive file system (ProFile$^{(R)}$) with constant pitch and helical angle. It seems that the radial lands play more important role in reducing screw-in effect.

• Journal of Acupuncture Research
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• v.22 no.3
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• pp.137-144
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• 2005

Objective : This study was designed to assess the heart rate variablitv of patients with Parkinson's disease according to Hoehn-Yahr stage. Methods : Subjects were voluntarily recruited by newspapers and internet. All the subjects are confirmed as idiopathic parkinson's disease by a neurologist. The patients were grouped by Hoehn-Yahr(H-Y) stage. Heart rate variability was measured for 5 minutes after 5 minutes' bed rest. Subjects were comprised of 3 groups which were H-Y stage I (n=14), H-Y stage H(n=9), H-Y stage III(n=7). We compared the heart rate variability of each groups by one-way ANOVA test. We also studied the relationship between UPDRS score and Heat rate variability components (SDNN, RMS-SD and TP) by pearson correlation analysis and simple linear regressin analysis Results: Age, duration was matched among groups. SDNN, RMS-SD, TP were significantly decreased as H-Y stage increased(p<0.05). Especially there was significant difference between H-Y stage I and III group(p<0.05). But other components(Heart rate, LF, HF, LF/HF ratio) were not showed significant difference. SDNN, RMS-SD and TP were significantly decreased as UPDRS scores increase(p<0.05). Conclusion : This study suggests that the function of the autonomic nervous system decreases as Parkinson`s disease progresses.

• Journal of Korean Academy of Nursing Administration
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• v.3 no.2
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• pp.41-59
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• 1997

This study surveyed nurses' value of reward and recognition level of organizational reward, and measured the fit of both. It also looked into the relationship between the reward fit and attitude of nurses toward their job and organization (job involvement${\cdot}$organizational commitment). It was planned to suggest the alternative of a future reward system. The sample consisted of 625 nurses of 8 private University Hospitals. Data for this study was collected from Mar. 25 to Apr. 17 by structured questionnaire. This study examined the differences of nurses' value of reward by their demographic characteristics, and looked into the relationship between the reward fit and job involvement${\cdot}$organizational commitment. Four instruments and a demographic questionnair were used to collect the data. Developed for myself and repaired by panel of judges, the value of reward scale and organizational reward scale consisted of 34 items on five points Likert-type scale. Developed by Kanungo and repaired by panel of judges, the job involvement scale measured overall job involvement on 7 items. The organizational commitment scale was developed by Mowday et al and repaired by panel of judges on 10 items. The data was analyzed by frequency, percentage, ranking, one-way ANOVA, Pearson's correlation coefficient, Chronbach alpha coefficient, t-test, SNK test, factor analysis with SPSS/PC+ progra,.Major findings are as follows 1. The mean of nurses' value of reward is 4.2435 and job content rewards are seen as the most important(M=4.5532). The following orders are seen as follows; financial rewards(M=4.4181), human realtion rewards(M=4.4130), establishment ${\cdot}$ facilities rewards(M=4.1632), professional rewards(M=4.1117), social status or prestige rewards(M=3.9228), career rewards(M=3.8816). Of 34 indivisual reward factors, the retainment allowance is seen to be thought of as the most important thing. 2. The mean of nurses' actual reward is 2.6035. The actual reward responded to the most extremely offered is job content rewards. The following orders are seen as follows ; human relation rewards(M=2.9420), financial rewards(M=2.7682), professional rewards(M=2.4601), social status or prestige rewards(M=2.3696), career rewards(M=2.3466), establishment ${\cdot}$ facilities rewards(M=1.9364). Of 34 indivisual reward factors, medical insurance benefits are felt to be most extremely offered. 3. The mean of fit of reward is -1.6874 and that means actual reward doesn't egual the value of the reward. What is offered mostly to nurses' value of reward is human relation rewards. The following orders are seen as follows; job content rewards(M=-1.5938), career rewards(M=-1.6381), social status of prestige rewards(M=-1.6382), financial rewards(M=-1.6836), professional rewards(M=-1.6854), establishment${\cdot}$facilities rewards(M=-2.3130). Of 34 indivisual factors, the item of fered most closely to nurses' value of reward is seen as the participation in educational programs at the nursing department of the hospital. 4. The mean of nurses' job involvement is 3.1987 and SD is 0.5667. 5. The mean of murses' organizational commitment is 2.9348 and SD is 0.6124, that is seen as a little lower than job involvement. 6. Significant value of reward differences were found among nurses by their demographic characteristics such as married status, tenure, academic career. 7. The fit of reward was significant related to job involvement and organizational commitment. When generalizing the result of this study, the value of reward, which nurses consider important and appropriate offers a reward that corresponds to the nurses' value of reward. This increases nurses' job and organization devotion further, as well as hospital effectiveness. It appears that nurses have recognized that the present reward offered in hospitals doesn't come up to their expectations so I think it is urgent to plan and perform the new reward system which is in accord with the nurses' reward fit.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.6
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• pp.753-759
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• 2007

Statement of problem. In distal extension removable partial denture, the preservation of health of abutment teeth is very important, but abutment teeth are subjected to unfavorable stress under unilateral loading specially. Purpose. The purpose of this study was to investigate the biomechanical effects of mandibular removable partial dentures with various prosthetic designs under unilateral loading, using strain gauge analysis. Material and methods. Artificial teeth of both canines were anchored bilaterally in a mandibular edentulous model made of resin. Bilateral distal extension removable partial dentures with splinted and unsplinted abutments were fabricated. Group 1: Clasp-retained mandibular removable partial denture with unsplinted abutments Group 2: Clasp-retained mandibular removable partial denture with splinted abutments by 6-unit bridge. Group 3: Bar-retained mandibular removable partial denture Strain gauges were bonded on the labial plate of the mandibular resin model, approximately 2 mm dose to the abutments. Two unilateral vertical experimental loadings (30N and 100N) were applied subsequently via miniature load cell that were placed at mandibular left first molar region. Strain measurements were performed and simultaneously monitored from a computer connected to data acquisition system. For within-group evaluations, t-test was used to compare the strain values and for between-group comparisons, a one-way analysis of variance (ANOVA) was used and Tukey test was used as post hoc comparisons. Results. The strain values of group 1 and 2 were tensile under loadings. In contrast, strain values of group 3 were compressive in nature. Strain values increased as the applied load in increased from 30N to 100N (p<.05) except for right side in group 1. Under 30N loading, in left side, group 1 showed higher strain values than groups 2 and 3 in absolute quantity (p<.05). And group 2 showed higher strain values than group 1 (p<.05). In right side, group 1 and 2 showed higher strain values than group 3 in absolute quantity (p<.05). Under 100N loading in left side, group 1 showed higher strain values than groups 2 and 3 in absolute quantity (p<.05). And group 2 showed higher strain values than group 1 (p<.05). In right side, group 1 and 2 showed higher strain values than group 3 in absolute quantity (p<.05). Under 30N loading, group 2 and 3 showed higher strain values in right side than in left side. Under 100N loading, right side strain values were higher than left side ones for all groups. Conclusion. Splinting of two isolated abutments by bridge reduced the peri-abutment strain in comparison with unsplinted abutments under unilateral loading. Bar-retained removable partial denture showed the lowest strain of three groups, and compressive nature.

• Journal of Korean Home Economics Education Association
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• v.18 no.3 s.41
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• pp.41-60
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• 2006

The system of teaching culinary practice needs drastic modification to catch up with dietary life and education curriculum changes. To reflect such changes, it is necessary to instill a strong will and interest as well as educational environment improvement in teachers. In this sense, this study researched the teachers' stages of concerns, levels of use, innovation configuration, and intervention demands, based on the CBAM(Concerns Based Adoption Method) developed by Hord et. al. For the survey, 500 questionnaires sent by mail and 187 were analyzed by SPSS/win 10.0 program. The results are summarized as follows. 1) The teachers stages of concerns on culinary practice is assessed to be in the lowest level of perceptual stage, which indicates a state of indifference. 2) In terms of the levels of use, routine use was the highest, followed by refinement use, integrated use, research use, and reinvent use in descending order. Mechanical use posted the lowest level. Even though the stages of concern showed the beginning stage, the Level of use was relatively high. 3) About the innovation configuration, approximately 30% of the teachers were not accomodate the culinary practice referred to the 7th National Education Curriculum. 4) According to the intervention demands on culinary practice education, it was found that teachers generally wanted more interventions in every component. Among the intervention components, the highest demand was on the support for facility. Demand on the financing is the second highest. Teachers in the level of routine use demanded more information and materials supply and individual encouragement, but teachers in the level of preparation needed study opportunity for training on operation skills more.

• Journal of Korean Home Economics Education Association
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• v.19 no.2
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• pp.1-12
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• 2007

This study analyzed the recognition and utilization regarding teacher's guidebook for middle school technology-home economics class in the 7th Educational Curriculum. The data were collected via e-mail to teachers teaching home economics in middle schools. These e-mail addresses were acquired from middle school web pages registered on the Educational Board. The 355 data were analyzed using the SPSS program. The results were as follows: First, teachers recognized highly the necessity of teacher's guidebook. However, as the actual guidebook was not adequately helpful, the overall degree of satisfaction was relatively low. Teachers utilizing guidebook had more positive recognition on teacher's guidebook than teachers who did not. And teachers majored in technology education thought teacher's guidebook more helpful compared with teachers majored in home economics education. Second, teachers referenced teacher's guidebook mostly for field practice guidance. Third, teachers who did not utilize teacher's guidebook used other reference materials such as Internet Web sites and audiovisual materials. They were most commonly used for the reason that the contents were ample and easy to access. Fourth, the followings were suggested to improve teacher's guidebook. The provision of learning contents that can be practically used in class, the various samples of teaching-learning method, the specified methods of planning and criteria for performance assessment, the adequate supplementations regarding textbook contents, and the improvement of the outward layout format of the guidebook.

• Journal of dental hygiene science
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• v.10 no.4
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• pp.265-271
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• 2010

This study was to investigate the level of knowledge, recognition, behavior of radiographic safety control and job stress in dental hygienists and to determine the relationship among variables. The subjects were 256(56.9%), who were worked in dental hospital and clinic with mean age of $29.59{\pm}7.30$. Data was collected using a self administrated questionnaire from April 4 to May 15, 2010. Behavior of radiographic safety control was measured using the 15-items and job stress was measured using the 5-items with 5-point likert scale. The data were analyzed with t-test, one-way ANOVA and pearson correlation coefficient using the SPSS WIN 17.0 program. Regarding job stress, the subjects was a mean of 2.63 out of a maximum 5 points. The level of knowledge, recognition, behavior of radiographic safety control a mean of 3.11, 4.08 and 3.43 out of a maximum 5 points. Recognition and behavior of radiographic safety control was negative related job stress in this study. Based on the findings, behavior of radiographic safety control is associated with job stress. These results suggest that various program should be considered for radiation safety control of dental hygienists.