• Imaging Science in Dentistry
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• v.32 no.2
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• pp.75-79
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• 2002

Purpose : To evaluate the effect of exposure time and image resolution on fractal dimension calculations for determining the optimal range of these two variances. Materials and Methods : Thirty-one radiographs of the mandibular angle area of sixteen human dry mandibles were taken at different exposure times (0.01, 0.08, 0.16, 0.25, 0.40, 0.64, and 0.80 s). Each radiograph was digitized at 1200 dpi, 8 bit, 256 gray level using a film scanner. We selected an Region of Interest (ROI) that corresponded to the same region as in each radiograph, but the resolution of ROI was degraded to 1000, 800, 600, 500, 400, 300, 200, and 100 dpi. The fractal dimension was calculated by using the tile-counting method for each image, and the calculated values were then compared statistically. Results: As the exposure time and the image resolution increased, the mean value of the fractal dimension decreased, except the case where exposure time was set at 0.01 seconds (α = 0.05). The exposure time and image resolution affected the fractal dimension by interaction (p<0.001). When the exposure time was set to either 0.64 seconds or 0.80 seconds, the resulting fractal dimensions were lower, irrespective of image resolution, than at shorter exposure times (α = 0.05). The optimal range for exposure time and resolution was determined to be 0.08- 0.40 seconds and from 400-1000 dpi, respectively. Conclusion : Adequate exposure time and image resolution is essential for acquiring the fractal dimension using tile-counting method for evaluation of the mandible.

• Korean Journal of Head & Neck Oncology
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• v.32 no.1
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• pp.1-5
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• 2016

Objectives: Frey's syndrome is an infrequent complication after parotidectomy and its incidence varies from 23.5% to 50.8% in the literature. The objective of this study was to evaluate the actual incidence and clinical characteristics of Frey's syndrome. Methods: We analyzed 31 patients who underwent parotidectomy and serial Minor's starch-iodine test. The mean follow-up period was $66{\pm}26.1$ months (range, 24-118 months). The Frey's syndrome was analyzed using a questionnaire for the assessment of the subjective symptom and Minor's starch-iodine test for the objective measurement at 1, 3, 6, and 12 months after the surgery and then every 6 or 12 months. Minor's starch-iodine test was graded from 0 to 3 according to the area of discolorization. Results: Frey's syndrome occurred in 11 patients (35.5%) on the Minor's starch-iodine test. The mean onset of Frey's syndrome on the starch-iodine test was $13.6{\pm}10.4$ months after parotidectomy. Sixteen patients (51.6%) complained about gustatory sweating and flushing. The onset of the subjective symptom was $11.27{\pm}6.96$ months after the surgery. There was a significant correlation between the grade of the starch-iodine test and the severity of subjective symptoms (P <0.001). Various factors including size and location of tumor, incision method, and extent of parotidectomy did not correlate with the Frey's syndrome. Conclusion: The incidence of Frey's syndrome was 35.5% on the Starch-Iodine test, and the onset was about postoperative 13.6 months.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.4
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• pp.512-519
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• 2013

The antioxidant activities of ethanolic extracts obtained from medicinal plants (Scutellaria baicalensis Georgi, Acanthopanax sessiliflorum Seeman, Pueraria lobata Ohwi, Portulaca oleracea Linne, Crataegus pinnatifida Bunge var. typica Schneider, Euonymus alatus Apterus, Hovenia dulcis Thunberg, Prunus yedoensis Matsumura, Albizzia julibrissin Durazz., Chrysanthemum indicum Linne) were evaluated for total phenolic content, total flavonoid content, DPPH radicals, nitrites, $Superoxide^-$ radicals, $ABTS^+$ radical scavenging activity, and reducing power. Antioxidant capacities were the highest in Prunus yedoensis Matsumura for DPPH radical scavenging activity ($IC_{50}$ $5.39{\mu}g/mL$), reducing power (2.72, $A_{700}$), and nitrite scavenging activity ($IC_{50}$ $167.94{\mu}g/mL$). Hovenia dulcis Thunberg and Acanthopanax sessiliflorum Seeman were effective for their nitrite scavenging activities (over 90% at 1 mg/mL). The $Superoxide^-$ radical scavenging activity of Prunus yedoensis Matsumura ($IC_{50}$ $43.39{\mu}g/mL$) was stronger than tannic acid ($IC_{50}$ $46.51{\mu}g/mL$). Five samples (Prunus yedoensis Matsumura, Acanthopanax sessiliflorum Seeman, Hovenia dulcis Thunberg, Crataegus pinnatifida Bunge var. typica Schneider, Scutellaria baicalensis Georgi) were effective for their $ABTS^+$ radical scavenging activity (more than 90% at 0.5 mg/mL). These results suggest that the ethanolic extracts of Prunus yedoensis Matsumura could be used as a functional ingredient in food products.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.4
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• pp.373-379
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• 2009

This study investigated oxygen consumption rate (OCR), $Q_{10}$ coefficient and ammonia excretion rate of the greenling, Hexagrammos otakii Jordan et Starks with the average body weight of 250 g in a semi-recirculated respiratory measuring system. The experiment was done under three different water temperatures (10, 15, $20^{\circ}C$) and five different ambient ammonia concentrations (0, 2.5, 5, 10, 20 mg/L). As the water temperature and ambient ammonia concentration increased the OCR has significantly increased (P<0.05). Given experimental conditions, the OCR of greenling were $50.8{\sim}159.4\;mg\;O_2\;kg^{-1}\;hr^{-1}$ and the relationship of water temperature (T) and ambient ammonia concentration (C) on the OCR were following: OCR = 41.3 - 1.87T - 7.38C + $0.463T^2$ + $0.66lC^2$ + 0.642TC - $0.011T^3$ - $0.010C^2$ - $0.031TC^2$ - $0.001T^2$C ($r^2$= 0.9226). $Q_{10}$ coefficients were $1.88{\sim}3.50$ for $10^{\circ}C$ to $15^{\circ}C$, $1.03{\sim}2.73$ for $15^{\circ}C$ to $20^{\circ}C$ and $1.40{\sim}1.90$ for $10^{\circ}C$ to $20^{\circ}C$, respectively. In general, the ammonia excretion rate tended to increase with increasing of the water temperature within normal ambient ammonia concentration. However, interestingly, it was observed that ammonia was absorbed rather than excreted above the ambient ammonia concentration of $2.5\;mg\;L^{-1}$, regardless of the water temperature. Thus, the largest ammonia absorption rate (AAR) was obserbed at the level of $98.4\;mg\;TAN\;kg^{-1}\;hr^{-1}$. The relationship ambient ammonia concentration (C) on AAR was following: Y = 1.61 + $10.9X^{0.7}$ ($r^2$ = 0.889).

• Asian Journal of Atmospheric Environment
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• v.6 no.4
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• pp.268-274
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• 2012

To perform quick measurements of black carbon (BC) particles deposited on foliar surfaces of forest tree species, we investigated an optical method for measuring the amount of BC extracted from foliar surfaces and collected on quartz fiber filters. The seedlings of Fagus crenata, Castanopsis sieboldii, Larix kaempferi and Cryptomeria japonica were exposed to submicron BC particles for one growing season (1 June to 7 December 2009). At the end of the growing season, the leaves or needles of the seedlings were harvested and washed with deionized water followed by washing with chloroform to extract the BC particles deposited on the foliar surfaces. The extracted BC particles were collected on a quartz fiber filter. The absorption spectrum of the filters was measured by spectrophotometer with an integrating sphere. To obtain the relationship between the absorbance of the filter and the amount of BC particles on the filter, the amount of BC particles on the filter was determined as that of elemental carbon (EC) measured by a thermal optical method. At wavelengths below 450 nm, the absorption spectrum of the filter showed absorption by biological substances, such as epicuticular wax, resulting in the low coefficient of determination ($R^2$) in the relationship between the amount of EC on the filter ($M_{EC}$, ${\mu}g\;C\;cm^{-2}$ filter area) and the absorbance of the filter. The intercept of the regression line between $M_{EC}$ and the absorbance of the filter at 580 nm ($A_{580}$) was closest to 0. There was a significant linear relationship between the $A_{580}$ and $M_{EC}$ ($R^2$=0.917, p<0.001), suggesting that the amount of BC particles collected on the filter can be predicted from the absorbance. This optical method might serve as a simple, fast and cost-effective technique for measuring the amount of BC on foliar surfaces.

• Journal of the Korean Magnetics Society
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• v.15 no.1
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• pp.1-6
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• 2005

In this study we investigate the electronic structure and magnetism of transition metal (TM = Ti, Cr, Mn, Fe, Co, Ni, Ru, Pd, Ag ) deped ZnO($TM_{0.25}Zn_{0.75}O$), which are expected to have Curie temperature. Full-potential Linearized Augmented Plane Wave(FLAPW) metod is adopted with exchange-correlation potential expressed as general gradient approximation(GGA). The calculated magnetic moments of ($TM_{0.25}Zn_{0.75}O$) are 0.83, 3.03, 4.03, 3.48, 2.47, 1.56, 0.43, 0.75, 0.01 ${\mu}_B$ for TM = Ti, Cr, Mn, Fe, Co, Ni, Ru, Pd, Ag, respectively. The nearest neighbor O atom to the transition metal is calculated to have a significant magnetic moment of about 0.1${\mu}_B$, ?? 새 strong hybridization between O-p and TM-d bands. As the results, the systems may have larger magnetic moments in total, compared to the corresponding isolated atoms. The 3d TM doped systems exhibit the half-metallic character except Co, wheres the 4d TM doped systems behave like normal metals and low spin polarization at the Fermi levels.

• Journal of Technologic Dentistry
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• v.38 no.2
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• pp.57-62
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• 2016

Purpose: The purpose of this study was to assess precision of crown prostheses that were fabricated by using 2 kinds of bur or 3 kinds of bur. Methods: The crowns were fabricated by using the first molar of the right maxillary in this study. The abutments that were prepared were scanned by using a scanner and designed by using CAD software. Based on the crown design, NC data were created with CAM software. The created NC data were used while fabricating the crown prostheses by using 5-axis milling machine. Scanning was done for the internal and external surface of the completed crown prostheses and 3-dimensional measurement was conducted for precision assessment. Results: The $RMS{\pm}SD$ value for the external surface of the crown prostheses that was fabricated by using two burs and three burs were $28.5{\pm}4.1{\mu}m$ and $19.1{\pm}2.8{\mu}m$, respectively; and the value for two burs were bigger than that for three burs with statistical significance (p<0.001). The $RMS{\pm}SD$ value for the internal surface of the crown prostheses that was fabricated by using two burs and three burs were $14.9{\pm}1.9{\mu}m$ and $13.3{\pm}2.5{\mu}m$, respectively; and the value for two burs were bigger than that for three burs but with no statistical significance. Conclusion: Based on this study, the prostheses that were fabricated by using 3 bur presented better stability compared to those that were fabricated by using 2 bur and statistically significant difference was found only in the external surface.

• Journal of dental hygiene science
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• v.16 no.1
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• pp.18-25
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• 2016

The purpose of this study was to investigate a reliability and validity of the Korean version for measuring tool the job embeddedness of dental hygienists. The survey was modified and revised to fit into Korean culture. A survey was conducted with 274 dental hygienists in dental clinics. The data was used for the analysis of the study, using PASW Statistics 18.0 and IBM SPSS AMOS 7.0. The factor analysis showed that the job embeddedness of the dental hygienists was composed of three elements, namely 'organization fit', 'job connectivity', and 'personnel relationships'. The validity of the model examined by a confirmatory factor analysis satisfied most of the relevant requirements. All of the factors had the conceptual reliability and variant extracted index above the minimum requirements, ensuring reliability and concentrated validity. The Cronbach's alpha shows a good reliability. In conclusion, it was proven that dental hygienist's job embeddedness measurement tool has high validity and reliability. Further, this study could be used to improve dental hygienist's long term working, and the growth stage of dental clinic.

• Journal of Digital Convergence
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• v.17 no.12
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• pp.565-573
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• 2019

This study was conducted on 236 dental hygienists to find ways to improve patient education by identifying their concern in preventive care, their level of prevention management knowledge, and their impact on patient education by mediating their prevention-related knowledge. It was found that the prevention care concern, prevention knowledge and patient education of dental hygienists have a significant correlation, the higher the prevention care concern, the better the patient education, the better the prevention care knowledge, the better the prevention management knowledge, the better the patient education. The regression analysis and Sobel verification were conducted in order to identify a mediating effect of the preventive care knowledge on the influence that the level of concern on preventive dental care affects the patient education. Therefore, it was confirmed that the level of concern on preventive dental care has not only a direct effect and an indirect effect. Based on the results of this study, it is believed that the preventive education effect of patients will be even higher if institutional support is supported along with the attention of dental hygienists on preventive work and education for preventive knowledge content.

• Restorative Dentistry and Endodontics
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• v.32 no.4
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• pp.313-326
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• 2007

The purpose of this study was to prove that an intermediate resin layer (IRL) oan increase the bond strength to dentin by reducing the permeability of single-step adhesives. Flat dentin surfaces were created on buccal and lingual side of freshly extracted third molar using a low-speed diamond saw under copious water flow. Approximately 2.0 mm thick axially sectioned dentin slice was abraded with wet #600 SiC paper. Three single-step self-etch adhesives; Adper Prompt L-Pop (3M ESPE, St Paul, MN, USA), One-Up Bond F (Tokuyama Corp, Tokyo, Japan) and Xeno III (Dentsply, Konstanz, Germany) were used in this study. Each adhesive groups were again subdivided into ten groups by; whether IRL was used or not; whether adhesives were cured with light before application or IRL or not; the mode of composite application. The results of this study were as follows; 1. Bond strength of single-step adhesives increased by an additional coating of intermediate resin layer, and this increasement was statistically signigicant when self-cured composite was used (p < 0.001). 2. When using IRL, there were no difference on bond strengths regardless the curing procedure of single-step adhesives. 3. There were no significant difference on bond strengths between usage of AB2 or SM as an IRL. 4. The thickness of Hybrid layer was correlated with the acidity of adhesive used, and the nanoleakage represented by silver deposits and grains was examined within hybrid and adhesive layer in most of single-step adhesives. 5. Neither thickness of hybrid layer nor nanoleakage were related to bond strength.