• The korean journal of orthodontics
• /
• v.25 no.3 s.50
• /
• pp.311-321
• /
• 1995

This study was undertaken to investigate the distribution of the chewing side preference and variations in the maximum bite force and facial morphology according to chewing side preference since unilateral chewing may cause morphologic and functional anomalies. 50 dental students who had no signs or symptoms of masticatory system and Angle's Class I relationship in posterior segments were selected, and divided into two groups, that is, 25 in bilateral chewing group(19 male and 6 female) and 25 in unilateral chewing group(10 male and 15 female). Maximum bite force was estimated ana posteroanterior cephalogram were measured ana statistically analyzed. The results were as follows : 1. Their were more students with bilateral chewing side preference($68\%$) and unilateral chewing side group consisted of right side preference($68\%$) and left side preference($32\%$). 2. There was no significant difference in the strength of max. bite force between the right and left side in bilateral chewing group. The bite force of the chewing side nab greater in the unilateral chewing group but less in the non-chewing side compared to those of bilateral chewing group with Bo significant difference. Max. bite force of chewing side was greater than that of non-chewing side in the unilateral chewing group(Female p<0.05). Max. bite force of males was about twice in that of females in both groups(p<0.05). Max. bite force of chewing side of the unilateral chewing group was similar to that of the bilateral chewing group, but that of non-chewing side was less than that of the bilateral chewing group. 3. In comparison of the facial morphology, there was no statistically significant difference in the size between the right and left side of the bilateral chewing group and between chewing and non-chewing side of the unilateral chewing group.

• The Journal of the Korea Contents Association
• /
• v.12 no.3
• /
• pp.244-250
• /
• 2012

The results of analyzing the difference between performances of individual dosimeters on this research subjecting the PLD and TLD, which are the official personal dosimeters, through dosimetry are as follows. After scanning the integral dose using an automatic scanner, the values of two devices that went through dose adjustment process had a statistical difference in TLD and PLD measurements under each filming conditions which were 70kVp, 200mA, 0.012sec and 42kVp, 100mA, and 0.012sec (p<0.001 and p<0.001 respectively). As for the difference of measurement value between DAP and the two particles under 70kVp, 200mA, 0.012sec filming condition, TLD had a value lower than DAP average value by $44.2mGy{\cdot}cm^2$ and PLD had a value of $246.8mGy{\cdot}cm^2$ which was lower than DAP average value by $15.5mGy{\cdot}cm^2$, while under 42kVp, 100mA, 0.012sec filming condition, TLD had a value lower than DAP average value by $17.9mGy{\cdot}cm^2$ and PLD had a value of $82.6mGy{\cdot}cm^2$ which was lower than DAP average value by 7.6$mGy{\cdot}cm^2$. Also, compared to PLD, each of 10 devices measured dose value in TLD had a larger deviation between the particles, and for a reproducibility test which repeatedly measured one particle, PLD had ${\pm}1%$ which was lower than TLD's ${\pm}2%$. As such, PLD had a superior performance result in dose measurement capacities aspect compared to TLD, and therefore we could verify that PLD is more appropriate and advantageous in managing radiation-related task performing worker's personal radiation exposure management in the diagnostic radiation field.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.37 no.4
• /
• pp.422-428
• /
• 2010

Giomer is fluoride-releasing, resin-based dental materials that comprise PRG(pre-reacted glass ionomer) filler. The purpose of this study was to evaluate the shear bond strength of Giomer using self-etching primer systems to bovine dentin. Bovine incisors were mounted in self-curing orthodontic resin and the facial surfaces were wet ground on SIC paper to expose the dentin. Total 100 samples were made and divided randomly into 4 groups, Giomer group(I), Composite resin group(II) and Compomer group(III), Giomer and single bottle adhesive group(IV). The shear bond strengths of 25 samples per each group were measured using universal testing machine. And data were analyzed statistically with One-way ANOVA and Scheffe test. Giomer group(I) showed the significantly higher bond strength than Compomer group(III)(p<0.05). There was no significant difference between Giomer group(I) and Composite resin group(II)(p>0.05). And there is no significant difference between gourp(I) and group(IV). Based on the results of present study, the use of Giomer as an esthetic restorative material for primary teeth might be justified. It is considered that more study about the fluoride releasing ability is needed to evaluate the anticariogenic effect of giomer.

• Journal of Korean Ophthalmic Optics Society
• /
• v.17 no.2
• /
• pp.177-184
• /
• 2012

Purpose: In this study, the effect of the eye movement direction on visual function related to accommodation was investigated when playing computer games for a certain period of time. Methods: Total 60 subjects in 20s who had the visual acuity of 1.0 or higher without any ocular disease and accommodative dysfunction were asked to play computer games separately in horizontal and vertical directions for 40 and 90 minutes and then measured their accommodative amplitude, accommodative facility, accommodative lag and relative accommodations. Thevisual function when not doing the computer game was regarded as a control value, and further compared and analyzed. Results: The accommodative amplitude, accommodative facility, accommodative lag and relative accommodations showed the tendency of decrease after the computer game for 40 minutes, and more reduced values of the visual functions were shown when the computer game extended up to 90 minutes except positive relative accommodation. Positive relative accommodation had a tendency to increase slightly after the computer game for 90 minutes. Meanwhile, the change of the visual functions was primarily influenced by the eye movement in horizontal direction rather than by the eye movement in vertical direction during computer game when analyzed by the direction of eye movement. Conclusions: Over all accommodative functions tended to decrease with the extended VDT working time by computer game, and the frequent eye movement in horizontal direction during VDT tasks could be the main cause of eyestrain since the eye movement in horizontal direction rather than vertical direction significantly affected the change of accommodative function.

• Journal of The Korean Association For Science Education
• /
• v.20 no.2
• /
• pp.234-243
• /
• 2000

This study investigated the relationships between verbal behaviors and chemistry problem solving ability in cooperative learning. Based on the previous chemistry achievement. 11th-graders were assigned heterogeneously into three-membered groups. Small cooperative group problem solving processes in using 4 stage-problem solving strategy were audio/video taped. Students' chemistry problem solving ability was then measured by a problem solving strategy performance test. Their verbal behaviors were classified into giving information, receiving information, asking questions, and disagreeing. These were further coded into 16 subcategories. Providing, a subcategory of giving information, was the most frequent behavior. In studying partial correlation between verbal behaviors and problem solving ability, 7 categories were found to have significantly positive relationships. Providing showed the highest correlation with the problem solving ability as reported previously. Moreover, this study also revealed significant correlations in the categories of clarifying provided, correcting, justifying, and clarifying. In the case of low-ability students, the verbal behaviors of giving or receiving information were strongly correlated with problem solving ability. However, these verbal behaviors did not enhance the problem solving ability of high- and medium-ability students.

• Journal of Chest Surgery
• /
• v.35 no.7
• /
• pp.511-516
• /
• 2002

Background: This study was undertaken in infant patients with isolated ventricular septal defect(VSD) to determine the effect of surgical closure on ventricular systolic time interval, as a parameter for ventricular performance, by echocardiography. Material and Method: Thirty patients were enrolled. Mean age of patients at operation was 6.5$\pm$3.2 months and all patients had non-restrictive VSD. We checked the left atrium/aorta(LA/Ao) ratio, left ventricle ejection fraction(EF), left ventricular systolic time interval(LVSTI), and right ventricular systolic time interval(RVSTI). Echocardiographic studies were done before surgical correction and postoperative periods(postopl: within 2 weeks, postop2: between 4 and 6 months, postop3: between 1 and 2 years). Result: LA/Ao ratio decreased significantly at immediate postoperative period compared to preoperative period and sustained during further follow-up period(from 1.74$\pm$0.37 to 1.36$\pm$0.24＊, 1.32$\pm$0.22＊, and 1.27$\pm$0.19＊, p<0.01). LV EF had not changed during follow-up periods(from 65.1$\pm$7.0 to 62.3$\pm$9.5, 62.8$\pm$5.7, and 64.1$\pm$6.9). LVSTI decreased significantly at postop2 and sustained during further follow-up period (from 0.46$\pm$0.13 to 0.46$\pm$0.11, 0.37$\pm$0.08＊, and 0.34$\pm$0.07＊, p<0.01). RVSTI decreased significantly at postop3(0.33$\pm$0.08 to 0.32$\pm$0.08, 0.31$\pm$0.07, and 0.27$\pm$0.05＊, p<0.01). Conclusion: We found that right and left ventricular systolic time intervals had decreased over the period of 1 year after surgical correction of VSD. Therefore, it is necessary to observe the change of ventricular function during that period.

• The Journal of Korean Society for Radiation Therapy
• /
• v.29 no.1
• /
• pp.77-84
• /
• 2017

Purpose: To evaluate the image quality improvement and dosimetric effects on virtual monochromatic images of a Dual Source-Dual Energy CT(DS-DECT) for radiotherapy planning. Materials and Methods: Dual energy(80/Sn 140 kVp) and single energy(120 kVp) scans were obtained with dual source CT scanner. Virtual monochromatic images were reconstructed at 40-140 keV for the catphan phantom study. The solid water-equivalent phantom for dosimetry performs an analytical calculation, which is implemented in TPS, of a 10 MV, $10{\times}10cm^2$ photon beam incident into the solid phantom with the existence of stainless steel. The dose profiles along the central axis at depths were discussed. The dosimetric consequences in computed treatment plans were evaluated based on polychromatic images at 120 kVp. Results: The magnitude of differences was large at lower monochromatic energy levels. The measurements at over 70 keV shows stable HU for polystyrene, acrylic. For CT to ED conversion curve, the shape of the curve at 120 kVp was close to that at 80 keV. 105 keV virtual monochromatic images were more successful than other energies at reducing streak artifacts, which some residual artifacts remained in the corrected image. The dose-calculation variations in radiotherapy treatment planning do not exceed ${\pm}0.7%$. Conclusion: Radiation doses with dual energy CT imaging can be lower than those with single energy CT imaging. The virtual monochromatic images were useful for the revision of CT number, which can be improved for target coverage and electron densities distribution.

• Journal of agricultural medicine and community health
• /
• v.38 no.4
• /
• pp.243-256
• /
• 2013

Objectives: This study was to investigate fear of falling and related factors in elderly living alone based on fall experience. Methods: Participants were 404 elderly women(faller=148, non-faller=256) over 65 years who were homebound living alone in Jeollanam-do Province. Face-to-face interviews were conducted using questionnaires from April $23^{th}$ to June $9^{th}$ 2013. The questionnaires consisted of demographic variables, fall experience, Fear of falling questionnaire(FOFQ), Falls Efficacy Scale(FES) and Center for Epidemiologic Studies Depression(CES-D). The collected data were analyzed using the SPSS version 14.0. Results: The fear of falling and the influential factors were different according to fall experience. Regression model for fear of falling in fallers significantly accounted for 46.1%(F=6.71, p<0.001); difficulty of performing activity, depression, fall-efficacy, static balance and assistive devices. Regression model for fear of falling in non-fallers significantly accounted for 55.2%(F=15.16, p<0.001); fall-efficacy, environmental hazards, difficulty of performing activity, risk of nutrition, housing type, dizziness and assistive devices. Conclusion: Results demonstrate that fall is an important health problem for elderly women living alone, and show fall experience for factors influencing fear of falling. These results could be used in the developing fall prevention programs.

• Journal of Periodontal and Implant Science
• /
• v.32 no.3
• /
• pp.457-473
• /
• 2002

The purposes of this study is to evaluate the combination effects of TGF-${\beta}_1$ and PDGF-BB on the periodontal ligament cells to use as a regeneration promoting agent of periodontal tissue. Human periodontal ligament cells were prepared from the first premolar tooth extracted for the orthodontic treatment and were cultured in DMEM/100% FBS at the $37^{\circ}C$, 5% $CO_2$ incubator. Authors measured the DNA synthesis, total protein, collagen and noncollagenous protein synthesis according to the concentration of TGF-${\beta}_1$,(1,5ng/ml) and PDGF-BB (1,10 ng/ml) in combination. To explore further this delayed effect of TGF-${\beta}_1$, we preincubated human periodontal ligament cells with TGF-${\beta}_1$ for 4 or 24 hours before PDGF-BB stimulation. The results were as follows: The DNA synthetic activity was increased dose dependently by TGF-${\beta}_1$, PDGF-BB. The combination of TGF-${\beta}_1$ and PDGF-BB consistently enhanced the DNA synthetic activity to PDGF-BB alone. The ability of TGF-${\beta}_1$ to enhance DNA synthetic activity in PDGF-BB treated periodontal ligament cells was dose dependent. The maximum mitogenic effect was at the 5ng/ml of TGF-${\beta}_1$ and l0ng/ml of PDGF-BB. Preincubation of cell with TGF-${\beta}_1$ resulted in significantly greater response to PDGF-BB at all TGF-${\beta}_1$ concentration studied, and may be useful for clinical application in periodontal regenerative procedures. The total protein, collagen and noncollagen synthesis was increased dose pendently by TGF-${\beta}_1$, PDGF-BB. The % of collagen was slightly decreased according to the concentration of TGF-${\beta}_1$, PDGF-BB. The effect of TGF-${\beta}_1$, PDGF-BB were not specific for collagen synthesis since it also increased noncollagenous protein synthesis. This study demonstrates that PDGF-BB is major mitogens for human periodontal ligament cells in vitro, and supports a role for TGF-${\beta}_1$ as a regulation of the mitogenic and total protein formation to PDGF-BB in these cells.