• Korean Journal of Materials Research
• /
• v.18 no.2
• /
• pp.84-91
• /
• 2008

The effects of the deposition and annealing temperature on the structural, electrical and optical properties of Ag doped ZnO (ZnO : Ag) thin films were investigated. All of the films were deposited with a 2wt% $Ag_2O-doped$ ZnO target using an e-beam evaporator. The substrate temperature varied from room temperature (RT) to $250^{\circ}C$. An undoped ZnO thin film was also fabricated at $150^{\circ}C$ as a reference. The as-grown films were annealed in temperatures ranging from 350 to $650^{\circ}C$ for 5 h in air. The Ag content in the film decreased as the deposition and the post-annealing temperature increased due to the evaporation of the Ag in the film. During the annealing process, grain growth occurred, as confirmed from XRD and SEM results. The as-grown film deposited at RT showed n-type conduction; however, the films deposited at higher temperatures showed p-type conduction. The films fabricated at $150^{\circ}C$ revealed the highest hole concentration of $3.98{\times}1019\;cm^{-3}$ and a resistivity of $0.347\;{\Omega}{\cdot}cm$. The RT PL spectra of the as-grown ZnO : Ag films exhibited very weak emission intensity compared to undoped ZnO; moreover, the emission intensities became stronger as the annealing temperature increased with two main emission bands of near band-edge UV and defect-related green luminescence exhibited. The film deposited at $150^{\circ}C$ and annealed at $350^{\circ}C$ exhibited the lowest value of $I_{vis}/I_{uv}$ of 0.05.

• The korean journal of orthodontics
• /
• v.49 no.1
• /
• pp.49-58
• /
• 2019

Objective: The aim of this retrospective study was to evaluate and compare the changes in the pharyngeal airway (PA), maxillary sinus volume, and skeletal parameters after rapid maxillary expansion (RME) and alternate rapid maxillary expansion and constriction (Alt-RAMEC) followed by facemask (FM) therapy. Methods: The records of 40 patients with skeletal Class III malocclusion due to maxillary retrognathism were collected, and the patients were assigned into two groups. The first group comprised 8 male and 12 female patients (mean age, $10.0{\pm}1.1years$) treated using RME/FM for an average of 10 months. The second group comprised 10 male and 10 female patients (mean age, $9.64{\pm}1.3years$) treated using Alt-RAMEC/FM for an average of 12 months. Cone-beam computed tomography images acquired before (T0) and after treatment (T1) were evaluated. Results: Regarding the skeletal effects, significant differences between the groups were the increase in ANS-HRP (perpendicular distance of ANS to the horizontal reference plane, 0.99 mm, p <0.05) in the Alt-RAMEC/FM group and the decrease in PP-SN (palatal plane to Sella-Nasion plane, $0.93^{\circ}$, p < 0.05) in the RME/FM group. Maxillary sinus volumes increased significantly in both the groups, and the increase was statistically significantly higher in the Alt-RAMEC/FM group. Although no significant intergroup differences were observed in PA volumes, both lower ($1,011.19mm^3$) and total ($1,601.21mm^3$), PA volume increased significantly in the Alt-RAMEC/FM group. Conclusions: The different expansion devices and protocols used with FM therapy do not seem to affect the forward movement of the maxilla and PA volumes. In contrast, the increase in maxillary sinus volume was greater in the Alt-RAMEC/FM protocol.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.49 no.1
• /
• pp.57-64
• /
• 2022

Additional dentition images are needed because the dentitions are distorted in cone-beam computed tomography (CBCT) due to streak artifacts and non-uniformity of the x-ray beam. The purpose of this study is to evaluate the feasibility of improving the dentition image of CBCT scan with intraoral scanner instead of plaster models. Maxilla images from plaster models, two intraoral scanners, and CBCT of 20 patients aged 12 to 18 were used in this study. With one of the intraoral scanners, the full arch was scanned by three segments and combined into a complete full arch. Virtual skull-dentition hybrid images from intraoral scanners were superimposed with the images from plaster models to evaluate the coordinate value difference and distance at reference points. The results showed that the coordinate value difference and distance were smallest with segmented intraoral scan, which showed only 2 ㎛ distance. Intraoral scan may provide good dentition images for virtual skull-dentition images.

• Geomechanics and Engineering
• /
• v.27 no.6
• /
• pp.537-550
• /
• 2021

There are various technical problems need to be solved in the construction process of pre-setting an isolation wall into a double lane in the outburst prone mine. This study presents a methodology that pre-setting an isolation wall into a double lane without a coal pillar. This requires the excavation of two small section roadways to dig a wide section roadway, followed by construction of the separation wall. During this process the connecting lane is reserved. In order to ensure the stability of the separation wall, the required bearing capacity of the isolation wall is 4.66 MN/m and the deformation of the isolation wall is approximately 25 cm. To reduce the difficulty of implementing support the roadway is driven by 5 m/d. After the construction of the separation wall, the left side coal wall is brushed 1.5 m to make the width of the gas roadway reach 2.5 m and the roadway support utilizes anchor rod, ladder beam, anchor cable beam and net configuration. During construction, the concrete pump and removable self-propelled hydraulic wall mold are used to pump and pour the concrete of the isolation wall. In the process of mining, the stress distribution of coal body and isolation wall is detected and measured on site. The results demonstrate that the deformation of the surrounding rock of roadway and separation of roof in the roadway is small. The stress of the bolt and anchor cable is within equipment tolerance validating their selection. The roadway is well supported and the intended goal is achieved. The methodology can be used for reference for similar mine gas control.

• Imaging Science in Dentistry
• /
• v.53 no.1
• /
• pp.69-75
• /
• 2023

Purpose: Maxillofacial trauma predominantly affects young adults between 20 and 40 years of age. Although radioprotection is a legal requirement, the significant potential of dose reduction in computed tomography (CT) is still underused in the clinical routine. The objective of this study was to evaluate whether maxillofacial fractures can be reliably detected and classified using ultra-low-dose CT. Materials and Methods: CT images of 123 clinical cases with maxillofacial fractures were classified by two readers using the AOCOIAC software and compared with the corresponding results from post-treatment images. In group 1, consisting of 97 patients with isolated facial trauma, pre-treatment CT images at different dose levels (volumetric computed tomography dose index: ultra-low dose, 2.6 mGy; low dose, <10 mGy; and regular dose, <20 mGy) were compared with post-treatment cone-beam computed tomography (CBCT). In group 2, consisting of 31 patients with complex midface fractures, pre-treatment shock room CT images were compared with post-treatment CT at different dose levels or CBCT. All images were presented in random order and classified by 2 readers blinded to the clinical results. All cases with an unequal classification were re-evaluated. Results: In both groups, ultra-low-dose CT had no clinically relevant effect on fracture classification. Fourteen cases in group 2 showed minor differences in the classification code, which were no longer obvious after comparing the images directly to each other. Conclusion: Ultra-low-dose CT images allowed the correct diagnosis and classification of maxillofacial fractures. These results might lead to a substantial reconsideration of current reference dose levels.

• Earthquakes and Structures
• /
• v.11 no.3
• /
• pp.483-503
• /
• 2016

This study aims to evaluate seismic performance of existing low and mid-rise reinforced concrete buildings by comparing their displacement capacities and displacement demands under selected ground motions experienced in Turkey as well as demand spectrum provided in 2007 Turkish Earthquake Code for design earthquake with 10% probability of exceedance in 50 years for soil class Z3. It should be noted that typical residential buildings are designed according to demand spectrum of 10% probability of exceedance in 50 years. Three RC building sets as 2-, 4- and 7-story, are selected to represent reference low-and mid-rise buildings located in the high seismicity region of Turkey. The selected buildings are typical beam-column RC frame buildings with no shear walls. The outcomes of detailed field and archive investigation including approximately 500 real residential RC buildings established building models to reflect existing building stock. Total of 72 3-D building models are constructed from the reference buildings to include the effects of some properties such as structural irregularities, concrete strength, seismic codes, structural deficiencies, transverse reinforcement detailing, and number of story on seismic performance of low and mid-rise RC buildings. Capacity curves of building sets are obtained by nonlinear static analyses conducted in two principal directions, resulting in 144 models. The inelastic dynamic characteristics are represented by "equivalent" Single-Degree-of- Freedom (ESDOF) systems using obtained capacity curves of buildings. Nonlinear time history analysis is used to estimate displacement demands of representative building models idealized with (ESDOF) systems subjected to the selected ground motion records from past earthquakes in Turkey. The results show that the significant number of pre-modern code 4- and 7-story buildings exceeds LS performance level while the modern code 4- and 7-story buildings have better performances. The findings obviously indicate the existence of destructive earthquakes especially for 4- and 7-story buildings. Significant improvements in the performance of the buildings per modern code are also obvious in the study. Almost one third of pre-modern code buildings is exceeding LS level during records in the past earthquakes. This observation also supports the building damages experienced in the past earthquake events in Turkey.

• Journal of Korean Dental Science
• /
• v.16 no.1
• /
• pp.63-73
• /
• 2023

Purpose: Hyperdontia is a developmental disorder of the oral cavity. Mesiodens refers to the hyperdontia located between the maxillary central incisors. During the surgical procedure, the anesthetic method for pain control should be considered along with factors related to the surgery itself. The purpose of this study was to evaluate the effect of the impacted position of the mesiodens on the selection of sedation method and to suggest incisive foramen as a brief reference. Materials and Methods: This study included 126 patients who were scheduled for extraction of mesiodens. The selection criteria included patients with one palatally impacted inverted mesiodens accessible from the palatal gingival margin, and those with good cooperation potential in order to control for clinical information. Using cone beam computed tomography, vertical, horizontal, and palatal positional factors were measured, and the anesthetic method was determined by two examiners. The patients were grouped into vertical and horizontal groups based on the position of the incisive foramen. Data were statistically analyzed using the Mann-Whitney test, the chi-square test, and logistic regression analysis. Result: All positional factors differed between the outpatient and inpatient anesthetic groups. The vertical minimum distance from the alveolar ridge to the mesiodens (Va) and the minimum distance from the palatal surface to the crown tip of the mesiodens (Tc) were factors affecting the choice of anesthetic method. The distribution of the vertical and horizontal positional groups differed between the outpatient and inpatient anesthetic groups. Conclusion: The incisive foramen can be used as a brief reference to determine the appropriate anesthetic method. Referral for inpatient anesthesia may be a priority if they are in the V₂H₂ group with Va ≥5 mm, and Tc ≥6 mm, and outpatient sedation may be considered if they are in the V₁H₁ group with Va ≤1.5 mm, and Tc ≤2.5 mm.

• Korean Journal of Optics and Photonics
• /
• v.34 no.6
• /
• pp.261-268
• /
• 2023

We propose a compact differential interference contrast microscopic module, which enables snapshot measurements for quantitative phase imaging. The proposed module adopts the lateral shearing interferometric principle, which can obtain self-interference without a reference. Due to the absence of the reference, the system is more stable than the typical interferometric systems. It uses a polarization grating to generate two laterally shifted wavefronts based on its birefringence and polarizing beam-splitting characteristics. Furthermore, the use of a polarization camera does not require sequential measurements for the phase extraction. In the experiments, we observe and measure the timely varying changes of various specimens to verify the system performance with the bright field images and phase contrast images. Because the proposed microscopic module also has the merit of being adaptable to typical microscopy instead of using an imaging camera, it can conveniently replace conventional contrast microscopy.

• Journal of Periodontal and Implant Science
• /
• v.49 no.5
• /
• pp.299-309
• /
• 2019

Purpose: To analyze the ridge profile of the anterior maxilla using cone-beam computed tomography and to assess the clinical significance of the ridge profile by performing virtual implant placement. Methods: Thirty-two cone-beam computed tomography scans of anterior maxillae were included. For each tooth, a vertical line was made along the longitudinal axis, and 3 horizontal lines at 1-, 3-, and 5-mm levels below the labial bone crest were drawn perpendicularly to the vertical reference. At these levels, the thickness of the alveolar ridge (RT), and the labial (LT) and palatal bone plate (PT) were measured. Then, virtual implant placement using standard and tapered implants was performed. A generalized linear mixed model was used for statistical analysis. Results: The teeth were located labially based on the proportion of LT and PT with respect to RT. At the 1-mm level, the value of LT was between $1.0{\pm}0.4mm$ for central incisors and $1.3{\pm}0.6mm$ for canines. A large number of teeth had area(s) with less than 1-mm-thick labial bone between the 1- and 5-mm levels below the crest. The mean PT was generally thicker than the LT in all tooth types. The greatest mean value of labial concavity was observed for canines, compared to other tooth types. Men had a greater RT than did women, but had a comparable LT. Less apical fenestration was observed when tapered implants were used. Conclusions: Most teeth in the anterior maxilla had a thin labial bone plate, with no significant difference between sexes. Tapered implants may be advantageous for the anterior maxilla.

• The Journal of Korean Society for Radiation Therapy
• /
• v.24 no.1
• /
• pp.15-21
• /
• 2012

Purpose: Image Guided Radiation Therapy (IGRT) has been carried out using On-Board Imager system (OBI) in Asan Medical Center. For this reason, This study was to analyze and evaluate the impact on Cone-Beam CT according to variation of material and respiration. Materials and Methods: This study was to acquire and analyze Cone-Beam CT three times for two material: Cylider acryl (lung equvalent material, diameter 3 cm), Fiducial Marker (using clinic) under Motion Phantom able to adjust respiration pattern randomly was varying period, amplitude and baseline vis-a-vis reference respiration pattern. Results: First, According to a kind of material, when being showed 100% in the acryl and 120% in the Fiducial Marker under the condition of same movement of the motion phantom. Second, According to the respiratory alteration, when being showed 1.13 in the baseline shift 1.8 mm and 1.27 in the baseline shift 3.3 mm for acryl. when being showed 1.01 in 1 sec of period and 1.045 in 2.5 sec of period for acryl. When being showed 0.86 in 0.7 times the standard of amplitude and 1.43 in 1.7 times the standard of amplitude for acryl. when being showed 1.18 in the baseline shift 1.8 mm and 1.34 in the baseline shift 3.3 mm for Fiducial Marker. when being showed 1.0 in 1 sec of period and 1.0 in 2.5 sec of period for Fiducial Marker. When being showed 0.99 in 0.7 times the standard of amplitude and 1.66 in 1.7 times the standard of amplitude for Fiducial Marker. Conclusion: The effect of image size of CBCT was 20% in the case of Fiducial marker. The impact of changes in breathing pattern was minimum 13% - maximum 43% for Arcyl, min. 18% - max. 66% for Fiducial marker. This difference makes serious uncertainty. So, Must be stabilized breathing of patient before acquiring CBCT. also must be monitored breathing of patient in the middle of acquire. If you observe considerable change of breathing when acquiring CBCT. After Image Guided, must be need to check treatment site using fluoroscopy. If a change is too big, re-acquiring CBCT.