• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.1
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• pp.9-20
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• 2023

Purpose: We investigated the effect of open tray impression using pick-up impression coping and close tray impression using transfer impression coping on the accuracy of impression in edentulous patients on their mandibular parts. the effect of material types of pick-up type impression copings for splinting in open tray impression on the accuracy of impression was also evaluated. Materials and Methods: Two implant fixtures were implanted in parallel in the left molar of the mandibular in the shape of a mandibular partial edentulous model. The 40 individual trays were fabricated using 3D printer. The prepared individual trays were classified into 4 groups (i.e., PN, PG, PH, and TN groups), and a total of 40 impression-takings were conducted. A master cast was connected to a Scan Body. The converted STL file was super-imposed on the scan images of the various groups. Results: The order of standard deviation values decreased as follows: PN (0.2343 ± 0.0844 mm), TN (0.2192 ± 0.0840 mm), indicating that the high accuracy of impression for TN group. In addition, for the comparison results between the material types used in splinting the open tray impression, the PH group showed a relatively lower standard deviation (0.1910 ± 0.1176 mm) than that of the PN group (0.2343 ± 0.0844 mm), PG group (0.2556 ± 0.1082 mm). Conclusion: The acrylic resin synthesized by light-induced polymerization exhibited a higher accuracy of impression taking than that of autopolymerizing acrylic resin. Meanwhile, the accuracy of impression taking was not dependent on the implant impression taking method or the presence of connection/fixation of impression copings.

• Journal of the Korean earth science society
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• v.44 no.6
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• pp.629-642
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• 2023

Currently, low and intermediate level radioactive waste is being disposed of at the Gyeongju disposal site for permanent isolation. Since 2006, the Korea Radioactive Waste Agency has been conducting site characteristics surveys continuously verifying changes in the site based on the site monitoring and investigation plan. The hydrogeochemical environment of the disposal site is considered for the evaluation of natural barriers. However, the seawater must be considered because of the regional characteristics of Gyeongju, which is near the East Sea. Therefore, this study, collected 30 samples for deriving the groundwater quality data from seven wells and compared with two seawater samples collected from October 2017 to June 2022. Additionally, the study explores the groundwater monitoring method using statistical tools such as clustering and background concentration analysis. The groundwater samples in the study area were classified into two to four clusters depending on their chemical constituents-especially, EC, HCO₃, Na, and Cl-using statistical analysis, molar ratio, and K-means clustering.

• Journal of Animal Science and Technology
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• v.65 no.5
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• pp.951-970
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• 2023

This study utilized Italian ryegrass silage (IRGS) - based total mixed ration (TMR) as feedstuff and evaluated its effects on rumen fermentation, growth performance, blood parameters, and bacterial community in growing Hanwoo heifers. Twenty-seven Hanwoo heifers (body weight [BW], 225.11 ± 10.57 kg) were randomly allocated to three experimental diets. Heifers were fed 1 of 3 treatments as follows: TMR with oat, timothy, and alfalfa hay (CON), TMR with 19% of IRGS (L-IRGS), and TMR with 36% of IRGS (H-IRGS). Feeding high levels of IRGS (H-IRGS) and CON TMR to heifers resulted in a greater molar proportion of propionate in the rumen. The impact of different TMR diets on the BW, average daily gain, dry matter intake, and feed conversion ratio of Hanwoo heifers during the growing period did not differ (p > 0.05). Furthermore, the blood metabolites, total protein, albumin, aspartate aminotransferase, glucose, and total cholesterol of the heifers were not affected by the different TMR diets (p > 0.05). In terms of rumen bacterial community composition, 264 operational taxonomic units (OTUs) were observed across the three TMR diets with 240, 239, and 220 OTUs in CON, L-IRGS, and H-IRGS, respectively. IRGS-based diets increased the relative abundances of genera belonging to phylum Bacteroidetes but decreased the abundances of genus belonging to phylum Firmicutes compared with the control. Data showed that Bacteroidetes was the most dominant phylum, while Prevotella ruminicola was the dominant species across the three TMR groups. The relative abundance of Ruminococcus bromii in the rumen increased in heifers fed with high inclusion of IRGS in the TMR (H-IRGS TMR). The relative abundance of R. bromii in the rumen significantly increased when heifers were fed H-IRGS TMR while P. ruminicola increased in both L-IRGS and H-IRGS TMR groups. Results from the current study demonstrate that the inclusion of IRGS in the TMR is comparable with the TMR containing high-quality forage (CON). Thus, a high level of IRGS can be used as a replacement forage ingredient in TMR feeding and had a beneficial effect of possibly modulating the rumen bacterial community toward mainly propionate-producing microorganisms.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.49 no.5
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• pp.252-261
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• 2023

Objectives: Patients undergoing oral surgery exhibit high anxiety, which may elevate their cortisol levels and affect postoperative recovery. Overweight patients are often encountered in the dental clinic due to the increasing prevalence of overweight. We aimed to investigate the relationships between preoperatively assessed body mass index (BMI), serum cortisol and high-sensitivity C-reactive protein (hs-CRP) levels, and visual analog scale (VAS) scores and preoperative anxiety in patients undergoing mandibular third molar (MM3) extraction and to identify predictors of postoperative complications. Patients and Methods: We analyzed 43 patients (age, 20-42 years) undergoing MM3 extraction. At the first visit, patients completed the Modified Dental Anxiety Scale (MDAS) and Amsterdam Preoperative Anxiety and Information Scale (APAIS) questionnaires. Their BMI and VAS scores were also calculated. The participants underwent blood tests 1 hour before MM3 extraction. On the first postoperative day, the participants' VAS scores and serum hs-CRP levels were reevaluated. Results: We found that BMI was significantly correlated with preoperative VAS scores. Further, BMI and preoperative hs-CRP levels were significantly correlated among women and patients undergoing extractions of fully impacted MM3s. No correlations were found between serum cortisol and other variables. The preoperative MDAS and VAS scores were significantly positively correlated, especially among patients undergoing extractions of fully impacted MM3s. Multiple linear regression showed that BMI and the eruption status of the MM3 were significant predictors of postoperative hsCRP levels and VAS scores, respectively. Conclusion: In MM3 removals, patients with higher BMI showed elevated hs-CRP and higher VAS scores before surgery. Patients with higher anxiety among those undergoing extractions of fully impacted MM3s showed higher preoperative VAS scores. The two main predictors of postoperative complications were BMI and MM3 eruption status.

• Resources Recycling
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• v.33 no.1
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• pp.22-30
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• 2024

To synthesize the Ti₃AlC₂ MAX phase, a crucial precursor for generating the two-dimensional material MXene, the use of Ti scrap as an initial material is an economically feasible approach. This study aims to optimize the synthesis conditions for the phase fraction of the Ti₃AlC₂ MAX phase utilizing Ti scrap as the Ti source. The deoxidation of Ti powders, prepared through the hydrogenation-dehydrogenation process from Ti scrap, was effectively accomplished using the deoxidation in solid-state (DOSS) process. The optimal synthesis conditions were established by blending DOSS-Ti, Al, and graphite powders with particle sizes ranging from 25 ~ 32 ㎛ in a molar ratio of 3:1.1:2. The resulting phase fractions were as follows: Ti₃AlC₂ at 97.25 wt.%, TiC at 0.93 wt.%, and Al₃Ti at 1.82 wt.%. Furthermore, the oxygen content of the Ti₃AlC₂ MAX powder, spanning from 25 ~ 45 ㎛, was measured at 4,210 ppm.

• The korean journal of orthodontics
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• v.54 no.3
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• pp.171-184
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• 2024

Objective: This study aimed to determine the maxillary and mandibular basal bone regions and explore the three-dimensional positional relationship between the dentition and basal bone regions in patients with skeletal Class I and Class II malocclusions with mandibular retrusion. Methods: Eighty patients (40 each with Class I and Class II malocclusion) were enrolled. Maxillary and mandibular basal bone regions were determined using cone-beam computed tomography images. To measure the relationship between the dentition and basal bone region, the root position and root inclination were calculated using the coordinates of specific fixed points by a computer program written in Python. Results: In the Class II group, the mandibular anterior teeth inclined more labially (P < 0.05), with their apices positioned closer to the external boundary. The apex of the maxillary anterior root was positioned closer to the external boundary in both groups. Considering the molar region, the maxillary first molars tended to be more lingually inclined in females (P = 0.037), whereas the mandibular first molars were significantly more labially inclined in the Class II group (P < 0.05). Conclusions: Mandibular anterior teeth in Class II malocclusion exhibit a compensatory labial inclination trend with the crown and apex relative to the basal bone region when mandibular retrusion occurs. Moreover, as the root apices of the maxillary anterior teeth are much closer to the labial side in Class I and Class II malocclusion, the range of movement at the root apex should be limited to avoid extensive labial movement.

• Journal of Korean society of Dental Hygiene
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• v.23 no.6
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• pp.431-439
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• 2023

Objectives: The aim of this study was to investigate the essential services, importance, interval of examinations, and role of dental hygienists in children's family dentistry program. Methods: A total of 124 participants completed a self-administered questionnaire. The data were analyzed using independent t-test, and ANOVA, and Pearson correlation analysis. Results: All participants stated that oral examination and panoramic radiography are required; children should be educated about brushing, use of oral products, and regular check-ups; and preventive treatments such as molar sealants and prophylaxis should be offered. They stated that light-curing resins and glass ionomer fillings should be offered in treatment services. They stated that examination intervals should be shorter for education and prevention rather than treatment. Dental hygiene students were more likely than dentists and dental hygienists to say that the program was more important. There was a correlation between oral examinations and education and treatment, and between essential services and their importance. Conclusions: Services considered essential and important should be provided first, education and prevention should be provided more frequently than treatment, and their importance should be emphasized not only to dental hygiene students but also to dental hygienists and dentists who are the main providers of services.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.2
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• pp.85-91
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• 2024

In this study, we investigated a method of growing single crystal 𝛽-Ga₂O₃ thin films on a c-plane sapphire substrate using MOCVD. We confirmed the optimal growth conditions to increase the crystallinity of the 𝛽-Ga₂O₃ thin film and confirmed the effect of the ratio between O₂ and Ga precursors on crystal growth on the crystallinity of the thin film. The growth temperature range was 600~1100℃, and crystallinity was analyzed when the O₂/TMGa ratio was 800~6000. As a result, the highest crystallinity thin film was obtained when the molar ratio between precursors was 2400 at 1100℃. The surface of the thin film was observed with a FE-SEM and XRD ω-scan of the thin film, the FWHM was found to be 1.17° and 1.43° at the and (${\bar{2}}01$) and (${\bar{4}}02$) diffraction peaks. The optical band gap energy obtained was 4.78 ~ 4.88 eV, and the films showed a transmittance of over 80% in the near-ultraviolet and visible light regions.

• Journal of Dental Rehabilitation and Applied Science
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• v.40 no.3
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• pp.169-178
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• 2024

Recently, several attempts have been made to integrate AI into the field of dentistry. To overcome the limitations of traditional fixed prosthetic fabrication methods such as CAD-CAM (computer-aided design-computer-aided manufacturing), AI programs are being developed for automated crown fabrication, and various studies are underway to applicate in clinical situation. In these case studies, single-unit fixed prostheses were fabricated using an AI program (Dentbird Crown, Imagoworks Inc, Seoul, Korea) in both the anterior and posterior regions and the fabrication time and accuracy were compared with previously used CAD-CAM method. The first case is a 44-year-old woman who presented for re-fabrication of a zirconia prosthesis due to a prosthesis fracture on the lingual side of the upper right lateral incisor. The second case is a 53-year-old male patient who presented for a crown restoration on an upper left first molar following root canal treatment, where he received a final zirconia restoration. In both cases, the first prosthesis was designed manually using a CAD program, the second prosthesis was designed using AI alone, and the third prosthesis was designed using AI and then modified by CAD program, and the three designs were superimposed to compare suitability. When evaluated after temporary placement, the final prosthesis demonstrates adequate stability, retention and support, resulting in functional and esthetic satisfaction.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.2
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• pp.89-97
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• 1986

To clarify the soil characteristics and genesis of the clayey terrace soils in Yeongnam area, the study were carried out with 9 typifying pedons of toposequential terrace soils in Yeongcheon (inland area) and Yeongil (coastal area) region. The results of soil genesis oriented investigations on soil mineralogical compositions and weathering characteristics were summarized as follows; 1. The contents of heavy minerals contained in sand fraction of the terrace soils were less than 5%, but the content in soil layers considered to be originated from other than terrace deposits had 9.8-16.2%. The content of feldspars in light minerals were higher in Yeongcheon sequence while the Yeongil sequence were characterized by having higher content in quartz. The ratios of quartz/feldspars in the soil layers where expecting lithological discontinuity, were different from that of terrace deposits. 2. The resistate index of maturity ranged around 76.7-29.9 in Yeongcheon area and around 85.6-67.2 in Yeongil area. The indices increased with the elevations of terraces. 3. The molar ratios of $SiO_2/Al_2O_3$ in clay fraction were around 1.93-2.65. The parent materials of the terrace deposits judged by the ratios of $Al_2O_3/TiO_2$ and $Fe_2O_3/Al_2O_3$ were considered to be the felsic materials. 4. The compositions of clay minerals detected by X-ray diffractogram and D.T.A. thermogram were dominated by kaolin and illite with subsidiary minerals of vermiculite, quartz, vermiculite intergrading to illite etc. It was distinguished from terrace deposits that by having higher amount of kaolin and montmorin minerals in the substrata of Bancheon soils in Yeongcheon area and Upyeong soils in Yeongil area, respectively.