• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.3
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• pp.389-407
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• 2017

In the current work, a series of three-dimensional finite element analysis was carried out to understand the behaviour of pile when the tunnel passes through the lower part of a single pile or group piles. At the current study, the numerical analysis analysed the results regarding the ground reinforcement condition between the tunnel and pile foundation. In the numerical modelling, several key issues, such as the pile settlements, the axial pile forces, the shear stresses and the total displacements near the tunnel have been thoroughly analysed. The pile head settlements of the single pile with the maximum level of reinforcement decreased by about 16% compared to the pile without ground reinforcement. Furthermore, the maximum axial force of the single pile with the maximum level of ground reinforcement experienced a 30% reduction compared to the pile without reinforcement. It has been found that the angle of ground reinforcement in the transverse direction affects the pile behaviour more so than the length of the ground reinforcement in the longitudinal direction. On the other hand, in the case of the pile group with the reinforced pile cap, the ground displacement near the pile tip appears to be similar to the corresponding ground displacement without reinforcement. However, it was found that the pile cap near the pile head greatly restrained the pile head movement and hence the axial pile force increased by about 2.5 times near the pile top compared to the piles in other analysis conditions. The behaviour of the single pile and group piles, depending on the amount of ground reinforcement, has been extensively examined and analysed by considering the key features in great details.

• Composites Research
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• v.32 no.6
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• pp.327-334
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• 2019

The delamination is a special mode of failure occurring in composite laminates. Several numerical studies with finite element analysis have been carried out on the delamination behavior of unidirectional composite laminates. On the other hand, the fracture for the multi-directional composite laminates may occur not only along the resin-fiber interface between plies known as interply or interlaminar fracture but also within a ply known as interyarn or intralaminar fracture accompanied by matrix cracking and fiber bridging. In addition, interlaminar and intralaminar cracks appear at irregular proportions and intralaminar cracks proceeded at arbitrary angle. The probabilistic analysis method for the prediction of crack growth behavior within a layer is more advantageous than the deterministic analysis method. In this paper, we analyze the crack path when the mode I load is applied to the cross-ply carbon/epoxy composite laminates and collect and analyze the probability data to be used as the basis of the probabilistic analysis in the future. Two criteria for the theoretical analysis of the crack growth direction were proposed by analyzing the stress field at the crack tip of orthotropic materials. Using the proposed method, the crack growth directions of the cross-ply carbon/epoxy laminates were analyzed qualitatively and quantitatively and compared with experimental results.

• Progress in Medical Physics
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• v.12 no.1
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• pp.19-29
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• 2001

In dose modeling, the shape of actual source and sealed capsule are important parameter to determine the physical dose computation. The author investigated the effect of filter of source self-absorption and sealed capsule to designed the high dose rate Ir-192 source for Ralstron(Japan) unit. The size of source designed to 1.5 mm $\Phi$ x 1.5mm length of actual source sealed with stainless steel which is 3.0mm $\Phi$ x 12.0mm length connected to driving cable. The dose attenuation was derived 66.3 % from 2655 segmented source at reference point of 10mm lateral distance of source. The output dose rate factor in tissue for designed source showed 0.0013511 cGy/mCi-sec in reference point at 1cm lateral distance of source center. The dose distribution at inferior of source showed the 52% of that of source tip region, however, the filtering effect was small as 4% at 45degrees of source axis. The dose attenuation within 20 degrees of source axis at near source-cable connector showed large filtering effect as 40% over, but the small effect was revealed isotropic dose distribution at large angle.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.2
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• pp.131-137
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• 2014

Purpose: This study examined the efficiency and wear of periodontal instrument sharpening using aluminum oxide stones with different levels of roughness. Materials and Methods: Thirty new No. 9-10 Gracey curets were used in this study. All curets had become dull after scaling and root planing. After similar blunting, the instruments were divided randomly into three groups (240, 600, 800 grit) containing 10 curets each. The stones were applied correctly to the lateral surface of each curet to maintain the $70-80^{\circ}$ angle. After resharpening, sharpness of the curets was examined by an optical microscope. After 20, 40, 60, and 80 strokes, the wear was measured at 1 mm and 2 mm from the tip of the cutting edge using a digital caliper. The data was analyzed statistically using analysis of variance (ANOVA) with repeated measures, 2-way ANOVA, and a Fisher's exact test. Results: The degree of sharpness increased significantly (P < 0.001) as the number of sharpening strokes grew for all stones. A comparison of the degree of sharpness on the same number of strokes showed that the 240 grit group significantly excelled the other groups on 5 and 10 strokes, respectively (P < 0.001). The mean wear showed no statistically significant difference among the groups (P > 0.05). Conclusion: The efficiency of Gracey curet resharpening was enhanced with more coarse stones, though we should consider the wear of the instrument during resharpening.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.40
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• pp.40.1-40.8
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• 2018

Background: A 9-year-old male showed severe defects in midface structures, which resulted in maxillary hypoplasia, ocular hypertelorism, relative mandibular prognathism, and syndactyly. He had been diagnosed as having Apert syndrome and received a surgery of frontal calvaria distraction osteotomy to treat the steep forehead at 6 months old, and a surgery of digital separation to treat severe syndactyly of both hands at 6 years old. Nevertheless, he still showed a turribrachycephalic cranial profile with proptosis, a horizontal groove above supraorbital ridge, and a short nose with bulbous tip. Methods: Fundamental aberrant growth may be associated with the cranial base structure in radiological observation. Results: The Apert syndrome patient had a shorter and thinner nasal septum in panthomogram, PA view, and Waters' view; shorter zygomatico-maxillary width (83.5 mm) in Waters' view; shorter length between the sella and nasion (63.7 mm) on cephalogram; and bigger zygomatic axis angle of the cranial base (118.2°) in basal cranial view than a normal 9-year-old male (94.8 mm, 72.5 mm, 98.1°, respectively). On the other hand, the Apert syndrome patient showed interdigitating calcification of coronal suture similar to that of a normal 30-year-old male in a skull PA view. Conclusion: Taken together, the Apert syndrome patient, 9 years old, showed retarded growth of the anterior cranial base affecting severe midface hypoplasia, which resulted in a hypoplastic nasal septum axis, retruded zygomatic axes, and retarded growth of the maxilla and palate even after frontal calvaria distraction osteotomy 8 years ago. Therefore, it was suggested that the severe midface hypoplasia and dysostotic facial profile of the present Apert syndrome case are closely relevant to the aberrant growth of the anterior cranial base supporting the whole oro-facial and forebrain development.

• Polymer(Korea)
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• v.36 no.2
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• pp.124-130
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• 2012

The uniform nanofibers of poly(L-lactide-$co$-${\varepsilon}$-caprolactone) (PLCL) with different contents of marine collagen (MC) were successfully prepared by electrospinning method. The effects of the major parameters in electrospinning process such as tip to target distance (TTD), voltage, nozzle size and flow rate on the average diameter of the electrospun nanofiber were investigated in generating composite nanofiber. The diameter and morphology of the nanofibers were confirmed by a scanning electron microscopy (SEM). Also, we measured a water contact angle to determine the surface wettability of the nanofibers. The average diameter of the nanofibers decreased as the value of TTD, MC contents, and voltages increased in comparison with that of pristine PLCL nanofiber. In contrast, the diameter of the nanofibers increased as the flow rate and inner diameter of nozzle increased in comparison with that of pristine PLCL. In addition, the hydrophilicity of the nanofiber and attachment of MG-63 cells on the sheets increased as incorporated collagen contents increased. Therefore, the marine collagen would be a potential material to enhance cellular interactivity of synthetic materials by mimicking the natural tissue.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.432-461
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• 1995

The basic principles in the design of Class II amalgam cavity preparations have been modified but not changed in essence over the last 90 years. The early essential principle was "extension for prevention". Most of the modifications have served to reduce the extent of preparation and, thus, increase the conservation of sound tooth structure. A more recent concept relating to conservative Class II cavity preparations involves elimination of occlusal preparation if no carious lesion exists in this area. To evaluate the ideal ClassII cavity preparation design, if carious lesion exists only in the interproximal area, three cavity design conditions were studied: Rodda's conventional cavity, simple proximal box cavity and proximal box cavity with retention grooves. In this study, MO amalgam cavity was prepared on maxillary first premolar. Three dimensional finite element models were made by serial photographic method. Linear, eight and six-nodal, isoparametric brick elements were used for the three dimensional finite element model. The periodontal ligament and alveolar bone surrounding the tooth were excluded in these models. Three types model(B option, Gap option and R option model) were developed. B option model was assumed perfect bonding between the restoration and cavty wall. Gap option model(Gap distance: $2{\mu}m$) was assumed the possibility of play at the interface simulated the lack of real bonding between the amalgam and cavity wall (enamel and dentin). R option model was assumed non-connection between the restoration and cavty wall. A load of 500N was applied vertically at the first node from the lingual slope of the buccal cusp tip. This study analysed the displacement, 1 and 2 direction normal stress and strain with FEM software ABAQUS Version 5.2 and hardware IRIS 4D/310 VGX Work-station. The results were as followed. 1. Rodda's cavity form model showed greater amount of displacement with other two models. 2. The stress and strain were increased on the distal marginal ridge and buccopulpal line angle in Rodda's cavity form model. 3. The stress and strain were increased on the central groove and a part of distal marginal ridge in simple proximal box model and proximal box model with retention grooves. 4. With Gap option, Rodda's cavity form model showed the greatest amount of the stress on distal marginal ridge followed by proximal box model with retention grooves and simple proximal box model in descending order. 5. With Gap option, simple proximal box model showed greater amount of stress on the central groove with proximal box model with retention grooves. 6. Retention grooves in the proximal box played the role of supporting the restorations opposing to loads.

• The korean journal of orthodontics
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• v.52 no.2
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• pp.150-160
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• 2022

Objective: To provide reliable prediction models based on dentoskeletal and soft tissue variables for customizing maxillary incisor positions and to optimize digitalized orthodontic treatment planning. Methods: This study included 244 Chinese women (age, 18-40 years old) with esthetic profiles after orthodontic treatment with fixed appliances (133 in group I: 1° ≤ The angle between the nasion [N]-A point [A] plane and the N-B point [B] plane [ANB] ≤ 4°; 111 in group II: 4° < ANB ≤ 7°). Dental, skeletal, and soft tissue measurements were performed on lateral cephalograms of the participants. Correlation and multiple linear regression analyses were used to determine the influence of dentoskeletal and soft tissue variables on maxillary incisor position. Results: The ideal anteroposterior position of the maxillary incisor varied between sagittal skeletal patterns. The position of the maxillary incisor correlated with the sagittal discrepancy between the maxilla and the mandible (ANB), protrusion of the midface, nasal tip projection, development of the chin, and inclination of both the maxillary and mandibular incisors. Distance from the maxillary central incisor to nasion-pogonion plane predicted using multiple linear regression analysis was accurate and could be a practical measurement in orthodontic treatment planning. Conclusions: Instead of using an average value or norm, orthodontists should customize a patient's ideal maxillary incisor position using dentoskeletal and soft tissue evaluations.

• Korean Journal of Ichthyology
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• v.35 no.2
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• pp.75-82
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• 2023

The samples used in this study were collected on two occasions (April 21 and May 16, 2021) from Liobagrus mediadiposalis and spawned egg masses located under rocks in Daeseocheon, Yeongdeok-gun, Gyeongsangbuk-do. Fertilized eggs ranged in size from 3.30~3.92 (average 3.57±0.19) mm (n=30), and it took 152~155 hours to hatch at water temperatures of between 17.0 and 20.0℃. Newly hatched larvae immediately post-hatching had a total length of 6.43~6.67 (6.55±0.07) mm (n=30), and were characterized by the retention of a yolk sac and an incompletely open mouth and anus, consistent with the yolk. On the 9 days post-hatching, the postflexion larvae had grown to length of between 11.0~13.8 (12.3±0.70) mm (n=30), and the caudal bone at the tip of the tail was bent upwards at an angle of 45°, thereby indicating the transition to the late larval growth stage. On the 16 days post-hatching, the total length of juvenile had increased to between 15.8~18.2 (16.8±0.77) mm (n=30), and the number of fins reached a fixed number of 8 dorsal, 17 anal, and 8 pelvic fins. On the basis of the findings of this study, we were able to confirm differences in the size of hatching larvae and fin mottle patterns in the early life history of related species.

• The korean journal of orthodontics
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• v.34 no.1 s.102
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• pp.1-11
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• 2004

Predicting the arch length discrepancy by simply comparing the available arch perimeter with tooth materials is merely a 2-dimensional analysis of the teeth movement. However, the real teeth movement takes place 3-dimensionally and is affected by various factors such as, the arch fen the curve of Spee and the axis of the incisors. The purpose of this study is to clarify the relationship between the decrease in the arch perimeter and the horizontal positional change of the incisors after extraction of the 1st bicuspids, for more analytic evaluation of the arch length discrepancy at pre-treatment model analysis stage. In addition to that to evaluate the effect of the curve of Spee, teeth axis to the basal plane, and the incisional crowding to the treatment outcome. All patients were treated at the department of orthodontics, dental hospital, Yonsei university. Inclusion criteria for patients selection were as follows. $\cdot$ Angle classification I malocclusion with bialveolar protrusion $\cdot$ Extraction of 4 1st bicuspids $\cdot$ No tooth anomaly or prosthesis $\cdot$ No abnormal attrition $\cdot$ No ectopically erupted teeth $\cdot$ Angle classification I canine and molar relationship $\cdot$ Less than 3mm of crowding Model analysis of the above patients was performed and the following conclusions were obtained. 1. When the intercanine distance was maintained, the available space for the distal movement of the mandibular incisors after the extraction of the 4 1st bicuspids was larger than the space provided by the extraction of the 4 1st bicuspids. However the difference was less than 1mm. The more tapered the anterior arch form, the larger the difference. 2. Compared to the situation in which the intercanine distance was maintained, when the intercanine distance was expanded to meet the width of the Posterior teeth, the incisors could move about 3mm more distally. 3. The positional difference of the incisal tip was insignificant whether the central incisors were moved by tipping or bodily movement. 4. When the anterior crowding was solved without changing the intercanine distance, the larger the anterior arch length was, the more the anterior movement of the incisors. 5. When the curve of Spee was levelled, the increase in the arch perimeter was less than half of the deepest curve of Spee.