• The Journal of Korean Academy of Prosthodontics
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• v.49 no.2
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• pp.145-151
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• 2011

Purpose: The purpose of this study was to compare the marginal fit of three-unit zirconia fixed dental prostheses (FDPs) fabricated using CAD/CAM and MAD/MAM system. Materials and methods: Dentiform maxillary central and lateral incisor were prepared for 3-unit FDP and fixed in yellow stone. This model was duplicated to epoxy resin die. On the resin die, fifteen 3-unit FDPs were fabricated. Metal-ceramic group was three-unit metal-ceramic FDPs, $Everest^{(R)}$ group was zirconia three-unit FDPs fabricated using the $Everest^{(R)}$ system (Kavo Dental GmbH, Biberach, Germany) and $Rainbow^{TM}$ group was zirconia three-unit FDPs fabricated using the $Rainbow^{TM}$ system (Dentium Co. Inc., Seoul, South Korea). They were cemented to resin dies with adhesive resin cement. After removing pontics, each retainers were separated and observed under measuring machine (Presize 440C) and analyzed through one-way ANOVA and Duncan test (${\alpha}$ = .05). Results: Mean values and standard deviations of marginal gap dimensions in each group for three-unit FDPs were $78.5{\pm}11.05\;{\mu}m$ for the metal-ceramic group, $59.30{\pm}11.63\;{\mu}m$ for the $Everest^{(R)}$ group and $70.34{\pm}13.98\;{\mu}m$ for the $Rainbow^{TM}$ group. Conclusion: 1. The $Everest^{(R)}$ group in comparison with metal-ceramic group showed better marginal fit, which had significant differences P<.05. 2. The mean marginal gap values between $Everest^{(R)}$ and $Rainbow^{TM}$ group did not showed significant differences (P>.05). 3. The mean marginal gap values between $Rainbow^{TM}$ group and metal-ceramic group did not showed significant differences (P>.05). 4. The mean marginal gaps of each group were within clinically acceptable range ($120\;{\mu}m$).

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.3
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• pp.375-388
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• 2019

Accurate evaluation of sea-to-air $CO_2$ flux and its variability is crucial information to the understanding of global carbon cycle and the prediction of atmospheric $CO_2$ concentration. $fCO_2$ observations are sparse in space and time in the East Sea. In this study, we derived high resolution time series of surface $fCO_2$ values in the southwest East Sea, by feeding sea surface temperature (SST), salinity (SSS), chlorophyll-a (CHL), and mixed layer depth (MLD) values, from either satellite-observations or numerical model outputs, to three machine learning models. The root mean square error of the best performing model, a Random Forest (RF) model, was $7.1{\mu}atm$. Important parameters in predicting $fCO_2$ in the RF model were SST and SSS along with time information; CHL and MLD were much less important than the other parameters. The net $CO_2$ flux in the southwest East Sea, calculated from the $fCO_2$ predicted by the RF model, was $-0.76{\pm}1.15mol\;m^{-2}yr^{-1}$, close to the lower bound of the previous estimates in the range of $-0.66{\sim}-2.47mol\;m^{-2}yr^{-1}$. The time series of $fCO_2$ predicted by the RF model showed a significant variation even in a short time interval of a week. For accurate evaluation of the $CO_2$ flux in the Ulleung Basin, it is necessary to conduct high resolution in situ observations in spring when $fCO_2$ changes rapidly.

• Journal of Korean society of Dental Hygiene
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• v.8 no.4
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• pp.19-30
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• 2008

This study reached the following conclusions as a result of carrying out the questionnaire survey of self-descriptions for the satisfaction after the citizens of Daejon uses the dental clinics, in order to identify the factors of satisfaction to the medical services of such dental clinics to be utilized in the patient management by dental hygienists, provide the basic data to provide the medical services desired by patients. 1. 43.9% men responded to the facilities and 56.1% women to the atmosphere for the standards of selection of dental clinics by general characteristic, and the college graduates or more to the kindness (38.2%), high-school graduates (43.2%) and middle-school graduates (25.9%) or less to the close distance for the level of educational attainment (p=0.009), which was meant to have a statistical significance. 2. The execution of reservation system for the dental clinics showed 54.7%, the reserved time was observed upon the execution of such reservation system, the dental clinics where they practice such system were 40.6%, and the confirmation methods was done through the telephone with 62.5%. 3. The experience of fear upon the dental treatment showed 74.6%. The type of fear showed the machine sound (48.7%) for men and cry of others for women (70.8%) at the highest. 70% of those under 30 at the age responded to the sharp instruments at the highest. 83.3% of Yousung-gu showed the highest by responding to the cry of others for the residential areas. The statistically significant difference was shown in both the age and residential area (p=0.000). 4. Women showed higher in the distribution of gender for the sterilization of instruments for the external satisfaction of dental clinics(p=0.000) and those under 30 at the age showed the highest with 2.98${\pm}$0.95(p=0.001). Seo-gu (3.48${\pm}$0.77) was the highest for the residential area (p=0.000), and there was statistically significant differences in the gender, age and residential area. 5. Men showed higher satisfaction than women in the clean state and the statistically significant differences were shown (p=0.000) at the age as the high satisfaction was shown for those under 30 at the age (2.35${\pm}$0.79), those having the income not less than 10 million won and not more than 20 million won (2.43${\pm}$0.78), and Seo-gu (2.63 ${\pm}$0.69) for the residential area. 6. For the internal satisfaction of dental clinic by users for the medical services in the dental clinics, 61.1% women responded to no in the ability of solving the inconvenience in the service process, and showed low ability of solving the inconvenience from 30 at the age (26.2%) and by responding to Dong-gu (22.1%) for the residential area, showing statically significant differences(p=0.000). For the re-use of dental clinics, 46.6% men (p=0.043) for the gender, 24.3% under 30 at the age and 22.9% of Dong-gu for the residential area responded to the re-use, showing statistically significant differences for the gender and residential area (p=0.000). 7. The dissatisfaction showed a high rate of 69.5% for the satisfaction to the medical services of dental clinics. 46.2% men responded to the pain and women to the feeling of foreign substance for the reason of dissatisfaction while those under 30 at the age showed 55.6% for others, those between 50 and 59 41.7% for the feeling of foreign substance. 86.3% carried out the education for cautions after the treatments and most people turned out that they do not carry out the continuous health management of mouth as 20.5% responded to that they carry out such health management.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.1
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• pp.43-48
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• 2014

Purpose: In the PET/CT images, The SUV (standardized uptake value) enables the quantitative assessment according to the biological changes of organs as the index of distinction whether lesion is malignant or not. Therefore, It is too important to enter parameters correctly that affect to the SUV. The purpose of this study is to evaluate an allowable error range of SUV as measuring the difference of results according to input errors of Activity, Weight, uptake Time among the parameters. Materials and Methods: Three inserts, Hot, Teflon and Air, were situated in the 1994 NEMA Phantom. Phantom was filled with 27.3 MBq/mL of 18F-FDG. The ratio of hotspot area activity to background area activity was regulated as 4:1. After scanning, Image was re-reconstructed after incurring input errors in Activity, Weight, uptake Time parameters as ${\pm}5%$, 10%, 15%, 30%, 50% from original data. ROIs (region of interests) were set one in the each insert areas and four in the background areas. $SUV_{mean}$ and percentage differences were calculated and compared in each areas. Results: $SUV_{mean}$ of Hot. Teflon, Air and BKG (Background) areas of original images were 4.5, 0.02. 0.1 and 1.0. The min and max value of $SUV_{mean}$ according to change of Activity error were 3.0 and 9.0 in Hot, 0.01 and 0.04 in Teflon, 0.1 and 0.3 in Air, 0.6 and 2.0 in BKG areas. And percentage differences were equally from -33% to 100%. In case of Weight error showed $SUV_{mean}$ as 2.2 and 6.7 in Hot, 0.01 and 0.03 in Tefron, 0.09 and 0.28 in Air, 0.5 and 1.5 in BKG areas. And percentage differences were equally from -50% to 50% except Teflon area's percentage deference that was from -50% to 52%. In case of uptake Time error showed $SUV_{mean}$ as 3.8 and 5.3 in Hot, 0.01 and 0.02 in Teflon, 0.1 and 0.2 in Air, 0.8 and 1.2 in BKG areas. And percentage differences were equally from 17% to -14% in Hot and BKG areas. Teflon area's percentage difference was from -50% to 52% and Air area's one was from -12% to 20%. Conclusion: As shown in the results, It was applied within ${\pm}5%$ of Activity and Weight errors if the allowable error range was configured within 5%. So, The calibration of dose calibrator and weighing machine has to conduct within ${\pm}5%$ error range because they can affect to Activity and Weight rates. In case of Time error, it showed separate error ranges according to the type of inserts. It showed within 5% error when Hot and BKG areas error were within ${\pm}15%$. So we have to consider each time errors if we use more than two clocks included scanner's one during the examinations.

• Korean Journal of Food Science and Technology
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• v.13 no.2
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• pp.153-159
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• 1981

A study was carried out to determine the optimal sterilization conditions of cooked rice packed in retort pouch and processed in a steam-air system retort. The cooked rice packed in retort pouch in various thickness (15, 20 and 25 mm) was processed at various heating temperature (110, 115 and $120^{\circ}C$) with $F_0$-value 6.0. In order to evaluate quality change during the thermal prosessing, C-values, based on z-value $33^{\circ}C$ and $F_0$ value 6.0, were also calculated at surface, center and mass average temperatures. Subsequent storage study revealed that the cooked rice packed in 15 mm thickness and processed at $120^{\circ}C$ with$F_0$-value 6.0 could be held without any spoilage and color change, when stored for 6 months at $38{\pm}1^{\circ}C$ under saturation humidity.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.43 no.2
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• pp.77-82
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• 2017

Objectives: The aim of this study was to compare the mechanical resistance of four different osteosyntheses modeled in two different sagittal split ramus osteotomy (SSRO) designs and to determine the linear loading in a universal testing machine. Materials and Methods: An in vitro experiment was conducted with 40 polyurethane hemimandibles. The samples were divided into two groups based on osteotomy design; Group I, right angles between osteotomies and Group II, no right angles between osteotomies. In each group, the hemimandibles were distributed into four subgroups according to the osteosynthesis method, using one 4-hole 2.0 mm conventional or locking plate, with or without one bicortical screw with a length of 12.0 mm (hybrid technique). Each subgroup contained five samples and was subjected to a linear loading test in a universal testing machine. Results: The peak load and peak displacement were compared for statistical significance using PASW Statistics 18.0 (IBM Co., USA). In general, there was no difference between the peak load and peak displacement related to osteotomy design. However, when the subgroups were compared, the osteotomy without right angles offered higher mechanical resistance when one conventional or locking 2.0 mm plate was used. One locking plate with one bicortical screw showed higher mechanical resistance ($162.72{\pm}42.55N$), and these results were statistically significantly compared to one conventional plate with monocortical screws (P=0.016) and one locking plate with monocortical screws (P=0.012). The difference in peak displacement was not statistically significant based on osteotomy design or internal fixation system configuration. Conclusion: The placement of one bicortical screw in the distal region promoted better stabilization of SSRO. The osteotomy design did not influence the mechanical behavior of SSRO when the hybrid technique was applied.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.381-391
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• 1999

A new 5th generation adhesive system(ONE-STEP) has been supplied which operators can apply to conditioned tooth surfaces by one simplified step. The purpose of this study was to determine whether different methods of adhesive application and various air drying duration after applying adhesive affect the shear bond strength of composite resin to dentin, and to evaluate the adhesive pattern of composite resin and dentin under SEM. Seventy-seven extracted human molar teeth were cleaned and mounted in palstic test tubes. The occlusal dentin surfaces were exposed with Diamond Wheel Saw and smoothed with Lapping and Polishing Machine (South Bay Technology Co., U.S.A.). Teeth were randomly divided into 7 groups (n=11), In experimental A group, adhesive was applied to dentin with agitation for 20 sec. In experimental N-A group, adhesive were continuously applied to dentin for 20 sec. Also control and experimental 1, 2, 3, 4 groups were dried for 10, 0, 5, 20, 30 seconds after applying adhesive, respectively, Adhesives were light cured for 10 sec. A gelatin capsule 5mm in diameter was filled with Aelitefil$^{TM}$ composite resin, placed on the treated dentin surface and light cured for 40 see, from three sides, All specimens were stored in distilled water at room temperature for 24 hours. The shear bond strengths were measured using a universal testing machine(AGS-1000 4D, Japan) at a crosshead speed of 5mm/min. An one-way ANOVA and LSD test were used for statistical analysis of the data. For SEM evaluation, seven specimens were made and sectioned. Representive postfracture and seven specimens were mounted on brass stubs, sputter-coated with gold and observed under SEM. The results were as follows : 1. The shear bond strength of experimental A group which adhesive were applied to dentin with agitation was higher than that of experimental N-A group (continuous application), and there was significant difference between two groups (p<0.01). 2. The interface between composite and dentin according to different application methods showed close adaptation in experimental A group and showed tinny gap in experimental N-A group. 3. The shear bond strength accoding to various air drying duration was the lowest value(7.57${\pm}$2.60 MPa) in experimental 1 group, so there was significant difference between experimental 1 group and other four groups (p<0.05). But there was no significant difference of shear bond strength between four groups (p>0.05). 4. The interface between composite and dentin according to various air drying duration showed close adaptation in control group and tinny gap in experimental 3 and 4 groups. But experimental 1 and 2 groups showed $30{\mu}$ and 6 - $10{\mu}m$ thick gaps, respectively.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.2
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• pp.89-96
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• 2018

Purpose: The aim of this study was to evaluate the effect of delayed time, surface treatment, and repair materials on repair of bis-acryl composite resin through comparison of shear bond strength and to evaluate the utility of bis-acryl composite resin repair using polymethyl methacrylate resin. Materials and Methods: A total of 90 bis-acryl composite resin specimens were fabricated and classified into 9 test groups, each of 10 pieces according to delayed time, surface treatment and repair material. The shear bond strength of each specimen was measured using a universal testing machine immediately after fabrication and analyzed using a statistical analysis program (IBM SPSS statistics 20). After the shear bond strength measurement, the fracture surface of the specimen was observed. Results: The highest shear bond strength ($17.54{\pm}3.14MPa$) was observed in the experimental group bonded immediately with a light-curing flowable composite resin using a bonding agent. Conclusion: When repairing bis-acryl composite resin, it is necessary to consider whether to remake according to the delayed time. For effective repair, it is desirable to consider appropriate materials and surface treatment methods according to the site or purpose of use.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.1
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• pp.1-11
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• 2020

Purpose: The purpose was to compare shear bond strength (SBS) of three types of resin for temporary restoration to polyetherketoneketone (PEKK) depending on surface modification. Materials and Methods: Sixty disks made from PEKK were air-abraded with 110 ㎛ alumina particles (Cobra, Renfert GmbH, Hilzinge, Germany) and thirty specimens were divided into two groups each: PEKK without Visio.link (Bredent, Senden, Germany)(U) and with Visio.link (P). Resins for temporary restoration (polymethylmethacrylate; PMMA, polyethylmethacrylate; PEMA, bis-acryl composite resin) in the shape of a square with one side 3.2 mm were bonded to PEKK twenty respectively and classified into six groups (UM, UE, UC, PM, PE and PC). All specimens were stored in distilled water at 37℃ for 24 hours. SBS of each group was measured at a crosshead speed of 2 mm/min in universal testing machine. SBS was compared using one-way ANOVA and a Tukey HSD test (P = 0.05). Results: Group UM and group UE showed a significant difference in SBS with group UC (P < 0.05). Group PC showed a significant increase in SBS than group UC (P < 0.05). Conclusion: It is recommended to apply Visio.link to PEKK for adhering bis-acrylic composite resin, but not for PMMA and PEMA in clinical practice.

• The Journal of Korean Society for Radiation Therapy
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• v.8 no.1
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• pp.109-114
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• 1996

PURPOSE : To investigate the effect of asymmetric jaws for delivering a uniform accurate dose of radiation to the junctions. METHODS & MATERIALS : A linear accelerator with a set of asymmetric jaws(varian 600C, 2100C, 2100CD with 4mev, 10mev, 10mev). Dose disribution was measured at the junctions with films in phantom. Total $10{\times}20cm^2$ with each $10{\times}10cm^2$ in deviation of ${\pm}1mm$ jaws. RESULTS : Film dosimetry showed the accuracy of asymmetric jaws depending on the machine. CONCLUSION : Understanding the mechanical characteristics of the use of half-beam at the junctions, without hot or cold regions.