• Korean Journal of Applied Biomechanics
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• v.13 no.2
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• pp.89-100
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• 2003

In this research was to analyze 3-D kinematics variables for handspring of basic motion in the heavy gymnastics in order to investigate kinematical difference between expert and novice. Therefore, the purpose of this research was provide quantitative information, systematic provision, rules, establishment of basic skill for improving skill and teaching athletes. And in the research, results were as followings. 1. In the time variables, total time was that expert took 0.745sec and novice took 0.829sec, and as duration time of each event, expert was faster than novice in the all motion event except till second event of the preparation motion. 2. In the center of body variables, vertical direction variables, the displacement of body center hight was that expert showed 61.26% and novice showed 54.48% in the third event of all motion, also all event were showed expert was higher displacement than novice except first of event in preparatory stage. 3. In the angle displacement of main joint, the right direction was that expert showed 154.12degree and novice showed 174.85degree and the left direction was that expert showed 159.29degree and novice showed 171.46degree In the second event of main joint curved point at the same time hand was reached floor. In the angle displacement of knee joint in the third event of all motion, expert showed 155.25degree and novice showed 154.00degree In right, and expert showed 155.24degree and novice showed 154.55degree in left. In this result, both were same motion type. In the angle displacement of hip joint in the third event of the all motion, expert showed 142.80degree and novice showed 134.17degree in right, and expert showed 140.28degree and novice showed 144.94degree in left. In this result, motion pattern of expert was same both sides, but novice was different. According to the results, to increase efficiency of motion and aesthetic effect in the all motion, it should stretch displacement and height of body center and make similarly angle of right and left joint.

• Geomechanics and Engineering
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• v.37 no.4
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• pp.307-321
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• 2024

This paper delves into the critical assessment of predicting sidewall displacement in underground caverns through the application of nine distinct machine learning techniques. The accurate prediction of sidewall displacement is essential for ensuring the structural safety and stability of underground caverns, which are prone to various geological challenges. The dataset utilized in this study comprises a total of 310 data points, each containing 13 relevant parameters extracted from 10 underground cavern projects located in Iran and other regions. To facilitate a comprehensive evaluation, the dataset is evenly divided into training and testing subset. The study employs a diverse array of machine learning models, including recurrent neural network, back-propagation neural network, K-nearest neighbors, normalized and ordinary radial basis function, support vector machine, weight estimation, feed-forward stepwise regression, and fuzzy inference system. These models are leveraged to develop predictive models that can accurately forecast sidewall displacement in underground caverns. The training phase involves utilizing 80% of the dataset (248 data points) to train the models, while the remaining 20% (62 data points) are used for testing and validation purposes. The findings of the study highlight the back-propagation neural network (BPNN) model as the most effective in providing accurate predictions. The BPNN model demonstrates a remarkably high correlation coefficient (R2 = 0.99) and a low error rate (RMSE = 4.27E-05), indicating its superior performance in predicting sidewall displacement in underground caverns. This research contributes valuable insights into the application of machine learning techniques for enhancing the safety and stability of underground structures.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.4
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• pp.89-96
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• 2007

The tunnel measurement data such as deficiency quantity, outbreak quantity, inner displacement and crown settlement are very important elements in tunnel sites under construction and obtained mostly by displacement gauge and total station. However, it is difficult and dangerous to install targets or measurement equipments on the points in tunnel construction site and also we need several persons to work in the tunnel. Non-prism total station with remote control system which is developed recently has various efficient functions for tunnel measurement. Therefore, for efficient tunnel measurement, this study suggested one person surveying system which consisted of non-prism total station and notebook PC to control total station remotely, and we evaluated the suggested tunnel measurement system. In this study, the tunnel site under construction was chosen as the test field and tunnel surveying was done by existing surveying method and suggested method separately. As result of the test, we analyzed processing time and accuracy to demonstrate the superiority of suggested one person non-prism surveying system.

• Geomechanics and Engineering
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• v.23 no.2
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• pp.139-149
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• 2020

Piles are widely used in structural foundations of engineering projects. However, the deformation of the soil around the pile caused by driving process has an adverse effect on adjacent existing underground buildings. Many previous studies have addressed related problems in sand and saturated clay. Nevertheless, the failure mechanism of pile driving in unsaturated soil remains scarcely reported, and this issue needs to be studied. In this study, a modeling test system based on particle image velocimetry (PIV) was developed for studying deformation characteristics of pile driving in unsaturated silt with different water contents. Meanwhile, a series of direct shear tests and soil-water characteristic curve (SWCC) tests also were conducted. The test results show that the displacement field shows an apparent squeezing effect under the pile end. The installation pressure and displacement field characteristics are sensitive to the water content. The installation pressure is the largest and the total displacement field is the smallest, for specimens compacted at water content of 11.5%. These observations can be reasonably interpreted according to the relevant unsaturated silt theory derived from SWCC tests and direct shear tests. The variation characteristics of the soil displacement field reflect the macroscopic mechanical properties of the soil around the pile.

• Structural Engineering and Mechanics
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• v.73 no.3
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• pp.239-257
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• 2020

In the present study, an innovative steel bracket and haunch hybrid scheme is devised, for retrofitting of earthquake damaged deficient beam-column sub-assemblages. Formulations are presented for evaluating haunch force factor under combined load case of lateral and gravity loads for the design of double haunch retrofit. The strength hierarchies of control and retrofitted beam-column sub-assemblages are established to showcase the efficacy of the retrofit in reversing the undesirable strength hierarchy. Further, the efficacy of the proposed retrofit scheme is demonstrated through experimental investigations carried out on gravity load designed (GLD), non-ductile and ductile detailed beam-column sub-assemblages which were damaged under reverse cyclic loading. The maximum load carried by repaired and retrofitted GLD specimen in positive and negative cycle is 12% and 28% respectively higher than that of the control GLD specimen. Further, the retrofitted GLD specimen sustained load up to drift ratio of 5.88% compared with 2.94% drift sustained by control GLD specimen. Repaired and retrofitted non-ductile specimen, could attain the displacement ductility of three during positive cycle of loading and showed improved ductility well above the expected displacement ductility of three during negative cycle. The hybrid haunch retrofit restored the load carrying capacity of damaged ductile specimen to the original level of control specimen and improved the ductility closer to the expected displacement ductility of five. The total cumulative energy dissipated by repaired and retrofitted GLD, non-ductile and ductile specimens are respectively 6.5 times, 2.31 times, 1.21 times that of the corresponding undamaged control specimens. Further, the damage indices of the repaired and retrofitted specimens are found to be lower than that of the corresponding control specimens. The novel and innovative steel bracket and haunch hybrid retrofit scheme proposed in the present study demonstrated its effectiveness by attaining the required displacement ductility and load carrying capacity and would be an excellent candidate for post-earthquake retrofit of damaged existing RC structures designed according to different design evolutions.

• Steel and Composite Structures
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• v.20 no.4
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• pp.749-776
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• 2016

In this paper, a Performance Based Design (PBD) approach is validated for multi-storey concentrically braced frame (CBF) systems. Direct Displacement Based Design (DDBD) procedure is used and validated by designing 4- and 12-storey CBF buildings. Nonlinear time history analysis (NLTHA) is used to check the performance of the design methodology by employing different accelerograms having displacement spectra matching the design displacement spectrum. Displacements and drifts obtained from NLTHA are found to fall within the design displacement limits used in the DDBD procedure. In NLTHA, both tension and compression members are found to be resisting the base shear, $F_b$, not only the tension members as assumed in the design methodology and suggested by Eurocode 8. This is the reason that the total $F_b$ in NLTHA is found to be greater than the design shear forces. Furthermore, it is found that the average of the maximum ductility values recorded from the time history analyses for the 4-and 12-storey buildings are close to the design ductility obtained from the DDBD methodology and ductility expressions established by several researchers. Moreover, the DDBD is compared to the Forced Based Design (FBD) methodology for CBFs. The comparison is carried out by designing 4 and 12-storey CBF buildings using both DDBD and FBD methodologies. The performance for both methodologies is verified using NLTHA. It is found that the $F_b$ from FBD is larger than $F_b$ obtained from DDBD. This leads to the use of larger sections for the structure designed by FBD to resist the lateral forces.

• Radiation Oncology Journal
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• v.30 no.1
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• pp.36-42
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• 2012

Purpose: To evaluate the radial displacement of clinical target volume in the patients with node negative head and neck (H&N) cancer and to quantify the relative positional changes compared to that of normal healthy volunteers. Materials and Methods: Three node-negative H&N cancer patients and five healthy volunteers were enrolled in this study. For setup accuracy, neck thermoplastic masks and laser alignment were used in each of the acquired computed tomography (CT) images. Both groups had total three sequential CT images in every two weeks. The lymph node (LN) level of the neck was delineated based on the Radiation Therapy Oncology Group (RTOG) consensus guideline by one physician. We use the second cervical vertebra body as a reference point to match each CT image set. Each of the sequential CT images and delineated neck LN levels were fused with the primary image, then maximal radial displacement was measured at 1.5 cm intervals from skull base (SB) to caudal margin of LN level V, and the volume differences at each node level were quantified. Results: The mean radial displacements were 2.26 (${\pm}1.03$) mm in the control group and 3.05 (${\pm}1.97$) in the H&N cancer patients. There was a statistically significant difference between the groups in terms of the mean radial displacement (p = 0.03). In addition, the mean radial displacement increased with the distance from SB. As for the mean volume differences, there was no statistical significance between the two groups. Conclusion: This study suggests that a more generous radial margin should be applied to the lower part of the neck LN for better clinical target coverage and dose delivery.

• The Journal of Engineering Geology
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• v.17 no.4
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• pp.567-576
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• 2007

In order to assess the on-site applicability of 3D absolute displacement monitoring of tunnel using digital photogrammetry, the displacement of the optical target placed at the measurement section was investigated, as planned in the OO tunnel construction site. The targets on 3 measurement lines only were considered for each point of measurement for the reconstruction of 3D cubic model for the digital vision monitoring. For each 3D model, 3 or more images have to be obtained at each point. On the last 2 measurement lines, 6 targets (crown, left and right walls) were continuously overlapped to construct 3D models so that 6 or more apices can be shared by 2 3D models. In order to compare the measurement methods of 3D absolute displacements in tunnel excavation, i. e, total station and digital image measurement, both the digital image measurement and optical measurement were conducted for 10 times in the same work section. The time and measurement results of both methods were compared.

• The Journal of Advanced Prosthodontics
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• v.11 no.2
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• pp.88-94
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• 2019

PURPOSE. This study was conducted to investigate patterns of adjacent tooth displacement in the posterior implant with interproximal contact loss (ICL) by 3-D digital superimposition method. MATERIALS AND METHODS. Posterior partially edentulous patients, restored with implant fixed partial prostheses before 2011 and suffered from food impaction of ICL between 2009 and 2011, were included. Two dental casts, at the time of delivery and at the time of food impaction in a same patient, was converted into 3-D digital models through scanning and superimposition was performed to assess chronologic changes of the dentition. Directions of tooth displacement were evaluated and the amount of ICL was calculated. Correlations between the amount of ICL and elapsed time, or between the amount of ICL and age after function, were assessed at a significance level of P<.05. RESULTS. A total number of 13 patients (8 males, 5 females) with a mean age of $65.76{\pm}9.94years$ and 17 areas (4 maxillae, 13 mandibles) were included in this retrospective study. Teeth adjacent to the implant restoration showed complex displacements but characteristic tendency according to the location of the arch. The mean amount of ICL was $0.33{\pm}0.14mm$. Elapsed time from function to ICL was $61.47{\pm}31.27months$. There were no significant differences between the amount of ICL and elapsed time, or age (P>.05). CONCLUSION. Natural teeth showed various directional movements to result in occlusal change in the arch. The 3-D superimposition of chronologic digital models was a helpful method to analyze the changes of dentition and individual tooth displacement adjacent to implant restoration.

• The Journal of Advanced Prosthodontics
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• v.14 no.2
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• pp.70-77
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• 2022

PURPOSE. This study evaluated screw loosening and 3D crown displacement after cyclic loading of implant-supported incisor crowns cemented with original titanium bases or with three compatible, nonoriginal components. MATERIALS AND METHODS. A total of 32 dental implants were divided into four groups (n = 8 each): Group 1 used original titanium bases, while Groups 2-4 used compatible components. The reverse torque value (RTV) was evaluated prior to and after cyclic loading (1,200,000 cycles). Samples (prior to and after cyclic loading) were scanned with a microcomputed tomography (micro-CT). Preload and postload files were superimposed by 3D inspection software, and 3D crown displacement analysis was performed using root-mean-square (RMS) values. All datasets were analyzed using one-way ANOVA and Tukey's post hoc analysis. RESULTS. Significant variations were observed in the postload RTV, depending on the titanium base brand (P < .001). The mean postload RTVs were significantly higher in Groups 1 and 2 than in the other study groups. While evaluating 3D crown displacement, the lowest mean RMS value was shown in the original Group 1, with the highest RMS value occurring in Group 4. CONCLUSION. Within the limitations of this in vitro study and under the implemented conditions, it was concluded that the manufacturer brand of the titanium base significantly influenced screw loosening following the fatigue test and influenced 3D crown displacement after cyclic loading.