• Imaging Science in Dentistry
• /
• v.49 no.1
• /
• pp.9-17
• /
• 2019

Purpose: This study aimed to introduce a novel method to evaluate the alveolar bone and interdental septum in the anterior mandible using cone-beam computed tomography (CBCT). Materials and Methods: Fifty-six CBCT scans from adult patients were selected. The CBCT scans were obtained before and after orthodontic treatment. The following measurements were taken: width of the alveolar bone and the interdental septum, height of the interdental septum, height of the bone plates, distance between the cementoenamel junction and marginal bone crests, and vertical positioning of the mandibular incisor, using the lingual plane as a reference. To test the reproducibility and the stability of the lingual plane, a triangle was traced in the anterior mandible. The intra-class correlation coefficient(ICC) was used to determine intra- and inter-examiner agreement. The paired Student t-test was used to evaluate the area of the triangle and the reproducibility of all measurements. Results: The ICC was excellent for the alveolar bone and dental measurements (0.9989 and 0.9977, respectively), as well as for the interdental septum (0.9987 and 0.9961, respectively). The area of the triangles showed stability in the lingual plane (P>0.05). For the alveolar bone, mandibular incisor, and interdental septum measurements, no statistically significant differences were found between the 2 examiners(P>0.05), confirming the technical reliability of the measurements. Conclusion: The method used in this study provides a valid and reproducible assessment of alveolar bone dimensions in the anterior mandible measured on CBCT images.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.5
• /
• pp.66-72
• /
• 2019

To improve ride quality and running stability of high speed train(HST), it is important that connection between coaches adopts the articulated bogies by using a gangway ring, unlike the conventional independent bogies assembled with car bodies. Although the gangway ring should be ensured absolute safety against passenger movement between coaches during train operation, there is still a lack of quantitative durability criteria of that. Therefore, in order to improve the passenger safety of HST, it is important to study the test requirements on durability evaluation for the ring. In this study, seven mixed loading cases were derived from the triaxial loading(vertical/lateral/longitudinal) modes. The safety factor of each component is at least 2.4 or more from the results of the finite element analysis. In addition, fatigue safety was evaluated through durability analysis from the viewpoint of strain-life design. Durability tests for the gangway ring carried out a total of 10 million cycles in 4 phases load conditions. After the durability test, the defect of each component was investigated using nondestructive testing techniques.

• The Journal of Korean Physical Therapy
• /
• v.33 no.6
• /
• pp.286-291
• /
• 2021

Purpose: This study aims to measure the improvement of balanced ability and rapid response of 30 healthy adults by performing dynamic stretching, static stretching, and sargent jump. Methods: The sample 30 peoples without any musculoskeletal disease who volunteered to be the subject of the study. We measured all subjects on following metrics to evaluate the function and stability under the normal condition, with dynamic stretching (DS) group, static stretching (SS) group: vertical jump height and reaching distance Anterior, Posteromedial, Posterolateral and NO (Normal eye open), NC (Normal eye close), PO (Pillow with eye open), and PC (Pillow with close eye) were evaluated. All measures were analyzed using independent t-test and One-way repeated Anova. Results: There was a significant increase in SJH (Sargent jump) in both groups (p<0.05). In Y-balance test, there was a significant increase in both groups except for the ANT (Anterior) direction, and there was a significant increase only in the SS group in the ANT (Anterior) direction (p<0.05). There was no significant difference between the DS group and the SS group (p>0.05). There was no significant improvement in ST (Stability Index) and WDI (Weight Distribution Index) in both groups (p>0.05). Conclusion: Both DS and SS showed significant improvement in SJH and Y-balance tests, which are dynamic functions, but had no significant effect on static balance ability.

• The Journal of Korean Academy of Prosthodontics
• /
• v.60 no.4
• /
• pp.330-338
• /
• 2022

For edentulous patients with unstable mandibular movements and abnormal facial features due to condylar fractures and morphological abnormalities, it is important to find a stable mandibular position. In this case, the patient's facial improvement, mandibular movement stability, and denture stability were improved by using flat table treatment dentures. In addition, computer-aided design/manufacturing (CAD-CAM) technology was used in denture fabrication to maintain the vertical dimension and lip support of flat table treatment dentures, we report good results in improving the patient's discomfort.

• Geomechanics and Engineering
• /
• v.29 no.3
• /
• pp.207-218
• /
• 2022

In submerged floating tunnels (SFTs), a next-generation maritime transportation infrastructure, the tunnel module floats in water due to buoyancy. For the effective and economical use of SFTs, connection with the ground is inevitable, but the stability of the shore connection is weak due to stress concentration caused by the displacement difference between the subsea bored tunnel and the SFT. The use of an elastic joint has been proposed as a solution to solve the stability problem, but it changes the dynamic characteristics of the SFT, such as natural frequency and mode shape. In this study, the finite element method (FEM) was used to simulate the elastic joints in shore connections, assuming that the ground is a hard rock without displacement. In addition, a small-scale model test was performed for FEM model validation. A parametric study was conducted on the resonance behavior such as the natural frequency change and velocity, stress, and reaction force distribution change of the SFT system by varying the joint stiffness under loading conditions of various frequencies and directions. The results indicated that the natural frequency of the SFT system increased as the stiffness of the elastic joint increased, and the risk of resonance was the highest in the low-frequency environment. Moreover, stress concentration was observed in both the SFT and the shore connection when resonance occurred in the vertical mode. The results of this study are expected to be utilized in the process of quantitative research such as designing elastic joints to prevent resonance in the future.

• Journal of the Korea Institute of Building Construction
• /
• v.22 no.1
• /
• pp.1-10
• /
• 2022

Recently, due to the frequent occurrence of localized torrential rains and heat waves caused by abnormal climates. For this reason, it is necessary to develop an economical and eco-friendly rainwater detention facility that can secure the groundwater level through rainwater detention as well as flood prevention against concentrated rainfall by simultaneously implementing rainwater permeation and storage. In this study, the structural safety of an eco-friendly rainwater infiltration type detention facility made using eco-friendly inorganic binders including red clay was examined. Static analysis considering the constant load and additional vertical load and dynamic analysis considering the seismic spectrum were performed. As a result, it was found that the eco-friendly prefabricated rainwater infiltration type detention facility developed in this study has a maximum stress of about 68.1% to 75.4% and a maximum displacement of about 0.9% to 9.6% under the same load and seismic conditions compared to the existing PE block rainwater detention facility. It was confirmed that the eco-friendly prefabricated rainwater infiltration type detention facility secured excellent structural stability.

• Geomechanics and Engineering
• /
• v.31 no.1
• /
• pp.15-30
• /
• 2022

Slope stability during the excavation of twin road tunnels is considered crucial in terms of safety. In this research, physical model testing and numerical analysis were used to investigate the characteristics of the settlement (uz) and vertical stresses (σz) along the two tunnel sections. First, two model tests for a (fill-rock) slope were conducted to study the settlement and stresses in presence and absence of slope support (plate support system). The law and value of the result were then validated by using a numerical model (FEM) based on the physical model. In addition, a finite element model with a slope supported by piles (equivalent to the plate) was used for comparison purposes. In the physical model, several rows of plates have been added to demonstrate the capacity of these plates to sustain the slope by comparing excavating twin tunnels in supported and unsupported slope, the results show that this support was effective in the upper part of the slope, while in the middle and lower part the support was limited. Additionally, the plates appear to induce less settlement in several areas of the slope with differing settlement and stress distribution as compared to piles. Furthermore, as a results of the previous mentioned investigation, there are many factors influence the stress and settlement distribution, such as the slope's cover depth, movement during excavation, buried structures such as the tunnel lining, plates or piles, and the interaction between all of these components.

• The Journal of Korean Academy of Prosthodontics
• /
• v.61 no.4
• /
• pp.356-366
• /
• 2023

Support, retention, and stability of dentures are key factors in the use of complete dentures in edentulous patients. With the development of digital dentistry, attempts are being made to replace traditional treatment methods. Also, struggle to reduce the number of patient visits and to manufacture high-quality digitally fabricated dentures are ongoing. In this case, a digital denture was restored using a tray capable of obtaining centric relation through gothic arch tracing and a facial scan. By replacing the traditional complete denture restoration method, the number of patient visits was reduced and esthetic results with satisfactory denture support, retention, and stability were obtained.

• Korean Journal of Applied Biomechanics
• /
• v.15 no.4
• /
• pp.43-53
• /
• 2005

This study is to define how the difference of athletic change influence on the last regrasp after somersault in Belle movement of parallel bars. For his study, the following conclusion was produced by analysis of athletic change by means of three dimensional visual image in three athlete of nation. 1. As the picture of S1, there are total used time(2.01 sec), S3(2.17 sec) and S2(2.19 sec). In case of a short needed time, it is difficult for them to perform the remaining movement of the vertical elevating flight easily and comfortably, it is judged as performing the small movement with restrict swing. 2 In the change of body center sped by each event, it is calculated as $-89.1^{\circ}$ the narrowest in S1, $-81.96^{\circ}$ the widest and then $86.34^{\circ}$ in S3. In E3 event, average compound speed is 4.07m/s, S2 showed the fastest speed of 4.14m/s whereas S1 the narrowest angle of 3.95m/s. 3. A shoulder joint and coxa are the period of mention in E3. In E4 which was pointed out the longest vertical distance, S2 that is indicated the highest vertical height as the period of detach in parallel bars. showed -3.91m. This is regarded as a preparatory movement for dynamic performance after using effectively elastic movement of shoulder joint and coxa while easily going up with turning back movement. In the 5th phrase, long airborne time and vertical change position is showed as the start while regrasping securely air flight movement from high position. 4. In E5, a long flight time and a long vertical displacement were shown as the regrasp after somersault efficiently in high position with stability from the point of the highest peak of the center of the body. Especially, S2 is marked as a little bit long position, while S1 is reversely indicated as performing somersault and unstable motion in a low position. 5. In E3, at the point of the largest extension of the shoulder joint and hip joint the shoulder joint is largely marked in $182^{\circ}$ and the hip point $182^{\circ}$ in S2. The shoulder joint is marked at the smallest angle in $177^{\circ}$ and the hip point $176^{\circ}$ in S1. And S1 is being judged by its performance of the less self - confident motion with lessening a breath of swing. S2 makes the most use of flexion and extension of the shoulder joint and the hip joint effectively. It was performed greatly with swinging and dropping the rotary movement and the rotary inertia naturally. 6. In E6, as the point of regrasp of the upper arm in parallel bars it is recognized by the that of components of vertical and horizontal velocity stably. During this study, the insufficient thing and the study on the parallel bars at a real game later are more activated than now. If it is really used as the basic materials by means of Belle Picked Study of Super E level after Bell movement, you may perceive the technique movement previously and perform without difficulty. Especially, such technique as crucifix is quite advantageous for oriental people thanks to small body shape condition. In conclusion we will nicely prepare for our suitable environment to gradually lessen trials and errors by analyzing and studying kinematically this movement.

• The Journal of Korean Academy of Prosthodontics
• /
• v.48 no.3
• /
• pp.202-208
• /
• 2010

Purpose: This study was aimed to evaluate the effect of rhPMP-2 coated implants on alveolar ridge augmentation in dogs. Materials and methods: Six Beagle dogs were used in this study. Six 8.0 mm long anodized surface titanium implants were placed 5 mm into the mandibular alveolar ridge following 6 month of healing period after extraction. Each animal received three implants coated with rhBMP-2 and three uncoated control implants using the randomized split-mouth design. Radiographic examinations were undertaken immediately at implant placement (baseline), at weeks 4 and 8 after implant placement. The amount of bone augmentation was evaluated by measuring the distance from the uppermost point of the coverscrew to the marginal bone. Implant Stability Quotient (ISQ) values were measured immediately at implant placement and 8 weeks after implant placement. For the statistical analysis, Man-Whitney ranksum test and Wilcoxon signed rank test of SPSS 12.0 software were used (P=.05). Results: The BMP group exhibited radiographic vertical bone augmentation about $0.6{\pm}0.7$ mm at 8 weeks later while controls showed bone loss about $0.4{\pm}0.6$ mm. There was significant difference among the rhBMP-2 group and controls in bone level change (P<.05). The ISQ values were significantly higher in the BMP-2 group than the control group at 8 weeks later (P<.05), while there was no significant difference at surgery. Conclusion: Within the limitation of this study, the rhBMP-2 coated on anodized implant could stimulate vertical alveolar bone augmentation, which may increase implant stability significantly on completely healed alveolar ridge.