• The KIPS Transactions:PartA
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• v.10A no.2
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• pp.165-172
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• 2003

In this paper, we constructed horizontal and vertical virtual spaces using the projection table and the projection wall. We then implemented a system that stereoscopically visualizes three-dimensional (3D) buildings in the virtual environments in accordance with the user's viewing point. The projection table, a kind of horizontal display equipment, is effectively used in reproducing operations on a table or desk as well as in areas that require bird-eye views because its viewing frustum allows to view things from above. On the other hand, the large projection wall, a kind of vertical display equipment, is effectively used in navigating virtual spaces because its viewing frustum allows to take a front view. In this paper, we provided quick interaction between the user and virtual objects by representing major objects as detail 3D models and a background as images. We also augmented the reality by properly integrating models and images with user's locations and viewpoint in different virtual environments.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.195-201
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• 2006

The wave load and its influence on the response of offshore structure have been well investigated through the statistical approach based on the linear theory. The linear approach has a limitation to apply the extreme condition such as freak wave, which corresponds to extreme value of wave spectrum. The main topic of present study is to develop an efficient numerical method to predict wave load induced by extreme wave. As a numerical method, finite element method based on variational principle is adopted. The frequency-focusing method is applied to generate the extreme wave in the numerical wave tank. The wave load on the bottom mounted vertical cylinder is investigated. The hydroelastic response of the vertical cylinder is also investigated so as to compare the wave loads with the rigid body case in the extreme wave condition.

• Journal of Navigation and Port Research
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• v.31 no.1 s.117
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• pp.21-27
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• 2007

The wave load and its influence on the response of offshore structure have been well investigated through the statistical approach based on the linear theory. The linear approach has a limitation to apply the extreme condition such as extreme wave, which corresponds to extreme value of wave spectrum. The main topic of present study is to develop an efficient numerical method to predict wave load induced by extreme wave. As a numerical method, finite element method based on variational principle is adopted. The frequency-focusing method is applied to generate the extreme wave in the numerical wave tank. The wave load on the bottom mounted vertical cylinder is investigated. The hydroelastic response of the vertical cylinder is also investigated so as to compare the wave loads with the rigid body case in the extreme wave condition.

• The Korean Journal of Physiology
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• v.16 no.1
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• pp.31-40
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• 1982

The present experiment was carried out to elucidate interrelation between the vestibular canals and the extraocular oblique muscles. In urethane anesthetized rabbits, excitatory or inhibitory effect of the canal was produced by three different methods; selective electrical stimulation of the ampullary nerve, bidirectional (ampullofugal or ampullopetal) lymphatic fluid flow, and rapid freezing of the canal. Changes of isometric tension as well as electro-myographic activity of the oblique muscles were recorded in the ipsilateral and contralateral eyes, by means of a polygraphic recorder, and the following results were obtained. 1) Electrical stimulation of a unilateral vertical or horizontal nerve caused contraction of superior oblique muscle and relaxation of inferior oblique muscle in the ipsilateral eye, and contraction of inferior oblique muscle and relaxation of superior oblique muscle in the contralateral eye. 2) Ampullofugal flow in a vertical canal and ampullopetal flow in a horizontal canal caused the oblique muscle responses which were identical to those responses produced by the electrical stimulation of the same canal nerve. 3) Rapid freezing of a vertical canal elicited the oblique muscle responses which were opposite to those caused by electrical stimulation of the same canal nerve. From the above experimental results, functional interrelation between the individual vestibular canal and bilateral extraocular oblique muscles were better elucidated. When these results were compared to those reported by previous investigators (Utzumi, Suzuki et al.), some important discrepancies were found between them. We ascribed such discrepancies to experimental errors of the previous investigators, since their results reflected theoretical contradictions in terms of vestibular eye movements.

• Steel and Composite Structures
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• v.25 no.6
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• pp.671-684
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• 2017

Elastic-plastic shear buckling behaviors of the web-post in a Castellated Steel Beam (CSB) with hexagonal web openings under vertical shear force were investigated further using Finite Element Model (FEM) based on a sub-model, which took the upper part of the web-post under horizontal shear force to represent the whole web-post under vertical shear force. A simplified design method for the web-post elastic-plastic shear buckling strength was proposed based on simulation results of the sub-model. Proper boundary conditions were applied to the sub-model to assure that its behaviors were identical to those of the whole web-post. The equation to calculate the thin plate elastic shear buckling strength was adopted as the basic form to build the design equation for elastic-plastic buckling strength of the sub-model. Parameters that might affect the elastic-plastic shear buckling strength of the whole web-post were studied. After obtaining the vertical shear buckling strength of a sub-model through FEM, the shear buckling coefficient k can be obtained through the back analysis. A practical calculation method for k was proposed through curving fitting the parameter study results. The elastic-plastic shear buckling strength of the web-post calculated using the proposed shear buckling coefficient k agreed well with that obtained from the FEM and test results. And it was more precise than those obtained from EC3 based on the strut model.

• Proceedings of the KOR-KST Conference
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• 1997.12b
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• pp.35-72
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• 1997

This study was conducted to develop a methodology to predict utility pole accident rates and to evaluate cost-effectiveness for safety improvement for utility pole accidents. The utility pole accident rate prediction model was based on the encroachment rate approach introduced in the Transportation Research Board special Report 214. The utility pole accident rate on a section of highway depends on the roadside encroachment rate and the lateral extent of encroachment. The encroachment rate is influenced by the horizontal and vertical alignment of the highway as well as traffic volume and mean speed. The lateral extent of encroachment is affected by the horizontal and vertical alignment, the mean speed and the roadside slope. An analytical method to generate the probability distribution function for the lateral extent of encroachment was developed for six kinds of encroachment types by the horizontal alignment and encroachment direction. The encroachment rate was calibrated with the information on highway and roadside conditions and the utility pole accident records collected on the sections of 55mph speed limit of the State Trunk Highway 12 in Wisconsin. The encroachment rate on tangent segment was calibrated as a function of traffic volume with the actual average utility pole accident rates by traffic volume strategies. The adjustment factors for horizontal and vertical alignment were when derived by comparing the actual average utility pole accident rates to the estimations from the model calibrated for tangent and level sections. A computerized benefit-cost analysis procedure was then developed as a means of evaluating alternative countermeasures. The program calculates the benefit-cost ratio and the percent of reduction of utility pole accidents resulting from the implementation of a safety improvement. This program can be used to develop safety improvement alternatives for utility pole accidents when a predetermined performance level is specified.

• PNF and Movement
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• v.18 no.3
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• pp.383-392
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• 2020

Purpose: Balance and gait dysfunction caused by aging affect elderly individuals' independent life, which, in turn, can reduce their overall quality of life. The purpose of this study is to compare the differences in the vestibular function of healthy elderly and young adults based on the subjective visual vertical (SVV) test as well as to compare and analyze the gait ability between these two groups to study the differences and association between vestibular, dizziness, and balance ability. Methods: The subjects were 18 young and 16 elderly adults with no neurological or musculoskeletal damage. To evaluate vestibular function, a subjective visual vertical test was performed. To evaluate the gait function, the step time, step length, stride length, stance phase ratio, and swing phase ratio were measured. Balance was evaluated using the Berg Balance Scale (BBS), and dizziness was evaluated using a dizziness handicap inventory (DHI). Results: There were significant differences in the SVV, BBS, and DHI between the young and elderly adults (p < 0.05). The gait variables of the older adults were all significantly different (except for the swing phase ratio) than those of the young adults (p < 0.05). As the result of correlation analysis, the SVV values of the young adults showed a significant negative correlation with step length and stride length (p < 0.05), while the SVV values of the elderly adults only showed a significant positive correlation with the DHI (p < 0.05). Conclusion: The elderly appeared to show a decrease in vestibular function when compared to the young adults, and it is thought that walking and balance function declined, while dizziness increased. Moreover, it is believed that these results can be used as basic data for vestibular rehabilitation in the future.

• Journal of Periodontal and Implant Science
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• v.52 no.1
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• pp.3-27
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• 2022

Purpose: This study was conducted to evaluate and compare the effects of different graft materials used in alveolar ridge preservation on dimensional hard tissue changes of the alveolar ridge, assessed using cone-beam computed tomography (CBCT) scans. Methods: A systematic electronic search of MEDLINE and the Cochrane Central Register of Controlled Trials and a manual search were conducted from November 2019 until January 2020. Randomized controlled trials were included if they assessed at least 1 variable related to vertical or horizontal hard tissue changes measured using CBCT scans. After a qualitative analysis of the included studies, subgroups were formed according to the graft material used, and a quantitative analysis was performed for 5 outcome variables: changes in vertical alveolar bone height at 2 points (midbuccal and midpalatal/midlingual) and changes in horizontal (buccolingual) alveolar bone width at 3 different levels from the initial crest height (1, 3, and 5 mm). Results: The search resulted in 1,582 studies, and after an independent 3-stage screening, 16 studies were selected for qualitative analysis and 9 for quantitative analysis. The metaanalysis showed a significantly (P<0.05) lower reduction of alveolar ridge dimensions for the xenogenic subgroup than in the allogenic subgroup, both vertically at the midbuccal aspect (weighted mean difference [WMD]=-0.20; standard error [SE]=0.26 vs. WMD=-0.90; SE=0.22) as well as horizontally at 1 mm (WMD=-1.32; SE=0.07 vs. WMD=-2.99; SE=0.96) and 3 mm (WMD=-0.78; SE=0.11 vs. WMD=-1.63; SE=0.40) from the initial crest height. No statistical analysis could be performed for the autogenic subgroup because it was not reported in sufficient numbers. Conclusions: Less vertical and horizontal bone reduction was observed when xenogenic graft materials were used than when allogenic graft materials were used; however, the loss of alveolar ridge dimensions could not be completely prevented by any graft material.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4146-4158
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• 2022

Ultra-high performance concrete (UHPC) has been widely utilized in military and civil protective structures to resist intensive loadings attributed to its excellent properties, e.g., high tensile/compressive strength, high dynamic toughness and impact resistance. At present, aiming to improve the defects of the traditional vertical concrete cask (VCC), i.e., the external storage facility of spent fuel, with normal strength concrete (NSC) shield, e.g., heavy weight and difficult to fabricate/transform, the feasibility of UHPC applied in the shield of VCC is numerically examined considering its high radiation and corrosion resistance. Firstly, the finite element (FE) analyses approach and material model parameters of NSC and UHPC are verified based on the 1/3 scaled VCC tip-over test and drop hammer test on UHPC members, respectively. Then, the refined FE model of prototypical VCC is established and utilized to examine its dynamic behaviors and damage distribution in accidental tip-over and end-drop events, in which the various influential factors, e.g., UHPC shield thickness, concrete ground thickness, and sealing methods of steel container are considered. In conclusion, by quantitatively evaluating the safety of VCC in terms of the shield damage and vibrations, it is found that adopting the 300 mm-thick UHPC shield instead of the conventional 650 mm-thick NSC shield can reduce about 1/3 of the total weight of VCC, i.e., about 50 t, and 37% floor space, as well as guarantee the structural integrity of VCC during the accidental drop simultaneously. Besides, based on the parametric analyses, the thickness of concrete ground in the VCC storage site is recommended as less than 500 mm, and the welded connection is recommended for the sealing method of steel containers.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.6
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• pp.939-946
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• 2018

In this work, we present simple schematics for a three-terminal graphene-based nanoelectromechanical switch with the vertical electrode, and we investigated their operational dynamics via classical molecular dynamics simulations. The main structure is both the vertical pin electrode grown in the center of the square hole and the graphene covering on the hole. The potential difference between the bottom gate of the hole and the graphene of the top cover is applied to deflect the graphene. By performing classical molecular dynamic simulations, we investigate the nanoelectromechanical properties of a three-terminal graphene-based nanoelectromechanical switch with vertical pin electrode, which can be switched by the externally applied force. The elastostatic energy of the deflected graphene is also very important factor to analyze the three-terminal graphene-based nanoelectromechanical switch. This simulation work explicitly demonstrated that such devices are applicable to nanoscale sensors and quantum computing, as well as ultra-fast-response switching devices.