• Structural Engineering and Mechanics
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• 제2권4호
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• pp.345-357
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• 1994

The differential equations governing free, in-plane vibrations of linearly elastic circular arches with variable cross-sections are derived and solve numerically for quadratic arches with three types of rectangular cross sections. Frequencies, mode shapes, cross-sectional load distributions, and the effects of rotatory inertia on frequencies are reported. Experimental measurements of frequencies and their corresponding mode shapes agree closely with those predicted by theory. The numerical methods presented here for computing frequencies and mode shapes are efficient and reliable.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.607-614
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• 2001

This paper describes the design and construction of main Arch bridge using Ultra-high performance concrete, Ductal in the Sunyudo pedestrian bridge project. Ductal is a new family of cementing materials with remarkable properties. Its mechanical characteristics reach unique values, with compressive strength in industrial use of 180 to 230 MPa and bending tensile strength of 50 to 80 MPa. By the use of Ductal, main Arch bridge crossing the Han-river is designed to the span 120m-long with optimized $\pi$ shape section.

• 치과방사선
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• 제6권1호
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• pp.39-44
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• 1976

The study was performed in order to avoid misunderstanding of the image production in the orthopantomograph and auther tried artificially, the object was not placed on the image layer children who was in mixed dentition was taken with 3 sheets of the film at one time. The results were obtained as following; 1. If the object was placed in front of the image layer and back of it, width of the anterior teeth was narrowed and widened. 2. If the object's midline was not placed on the median line of the equipment, the one side was narrowed and the another side was widened. 3. If the head was inclined upward and downward, the former was shown V shape and the latter was shown inverted V shape outline of the arches. 4. In mixed dentition, auther obtained in each other that the image layer was placed on the deciduous arch, on the permanent arch, in the middle of the deciduous teeth and permanent teeth at one exposure.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1989년도 춘계학술대회
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• pp.9-12
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• 1989

A preliminary study has been conducted to demonstrate the effect of laser heat treatment on Ni Ti alloy dental arch wires ($0.016"\;{\times}\;0.022"$ and $0.018"\;{\times}\;0.026"$, rectangular shape). Changes in mechanical and thermal properties and surface morphologies are investigated by using optical and scanning electron microscope (SEM), energy dispersive x-ray microprobe analysis(EDX), differential scanning calorimeter (DSC), and micro hardness tester. The results indicate that the laser can affect the thermal equilibrium state of the localized surface. Titanium rich surface film is formed by the laser treatment. The surface film and rapidly resolidified underlying structures show better chemical resistance than the matrix material. Phase transition temperatures which are related to shape recovery temperatures are changed after laser treatment. Hardness of resolidified area and heat affected zone are lower than before treatment.

• 한국소음진동공학회논문집
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• 제19권3호
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• pp.301-312
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• 2009

This paper presents a theoretical approach to calculate the resonant frequency of a thickness vibration mode in the radial direction for a 1-3 piezoelectric composite transducer of circular arch shape. For the composite transducer composed of a piezoelectric ceramic and a polymer, vibration parameters were derived according to the volume ratio of a ceramic, and a vibration characteristic equation was derived from the piezoelectric governing equations with adequate boundary conditions. The fundamental resonant frequencies were calculated numerically and verified by comparing them with those obtained from the finite element analysis and the experiment. The volume ratio and the thickness are more substantial than the curvature radius to determine the fundamental resonant characteristics, and the fundamental resonant frequency becomes higher for the larger volume ratio of the piezoelectric ceramic and for the smaller thickness.

• 대한치과의사협회지
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• 제53권7호
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• pp.457-467
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• 2015

Patients with cleft lip and palate require interdisciplinary treatment to achieve successful rehabilitation. However, there are special difficulties in orthodontic treatment of adult cleft lip and palate patients: 1. Lack of Tissue, Bone, and Soft tissue; 2. Heavy Scar Tissue, Vestibule, and Palate; 3. Severe Anteroposterior discrepancy and Impaired Maxilla; 4. Distortion of Alveolar Ridge; 5. Abnormal Eruption Path and Malalignment of Tooth. Solving these problems, orthodontist should have differential diagnosis on extent of cleft site and residual deformities of adult cleft lip and palate patient. The tooth missing area in cleft site was commonly treated with a removable or fixed prosthesis, but this method is not stable to retain maxillary arch shape. To establish the more stable arch shape in cleft lip and palate, endosseous implants in the alveolar clefts with bone graft is helpful for management of adult cleft lip and palate patient.

• 한국산학기술학회논문지
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• 제19권10호
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• pp.24-30
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• 2018

지하공간의 수요가 증가되면서 지중구조물의 기능을 저하시키는 상재하중 및 토피증가에 대한 구조물의 안정성 문제를 해결하기 위해 많은 연구자들이 고압축성 물질을 이용한 하중저감방법 연구를 진행해왔다. 본 논문은 하수관거에 작용하는 하중을 EPS Geofoam을 활용하여 경감시키는 하중저감공법을 아치구조물에 적용하고 그 효과를 증가시키기 위한 최적의 Soft Zone 적용방법에 대해 기술하고 있다. 지반구조 상호작용을 고려한 ABAQUS 유한요소해석을 통해 아치구조물의 거동 특성을 파악하고 4가지 EPS Geofoam 형식을 해석적으로 분석하여 최적의 적용형상을 확인하였다. 해석 결과를 토대로 선정된 최적 단면 형상에 대해 아치구조물의 라이즈비, 지간길이 변화를 해석변수로 고려하여 발생하는 토압감소율을 비교하여 적용성을 분석하였다. 수치해석에서 선정한 최적 Soft Zone를 적용한 아치구조물에 발생하는 토압이 평균 78% 감소되는 것을 확인하였다. 본 연구 결과에서 EPS Geofoam의 토압 경량화 효과와 이에 대한 지중아치구조물의 적용성 평가는 지중구조물 설계 시 경제적이고 합리적인 방법을 제공해 줄 것이며, 향후 심층 지하공간에 대한 활용성 증가에 도움이 될 것이다.

• 농촌계획
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• 제18권3호
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• pp.57-65
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• 2012

This research is focus on the analysis of bridge image and preference. In this study, 3 types of bridge with arch bridge, cable stayed bridge, and suspension bridge, 4 prospect points named A, B, C, and D will be simulated in one scene for final analysis of bridge image and preference.On prospect point A, higher evaluation is received among the arch bridge. In addition, for cable stayed bridge and suspension bridge, the Higher evaluation is received among the most at the arch bridge on prospect point B. At the on prospect point C, higher evaluation is received among the most cable stayed bridge and suspension bridge compared with arch bridge. At the on prospect point D, lower evaluation is received among the cable stayed bridge and suspension bridge compared with arch bridge. The highest average total preference is received for cable stayed bridge. And, The lowest average total preference is received for arch bridge. Cable stayed bridge is suitable for the Baegya Bridge than arch bridge in the Landscape point. In conclusion, the preference for one bridge is not the same at different prospect points through above research.

• Smart Structures and Systems
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• 제32권5호
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• pp.319-338
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• 2023

The study presents a new hybrid data-driven method by combining radial basis functions neural networks (RBF-NN) with the Jaya algorithm (JA) to provide effective structural health monitoring of arch dams. The novelty of this approach lies in that only one user-defined parameter is required and thus can increase its effectiveness and efficiency, as compared to other machine learning techniques that often require processing a large amount of training and testing model parameters and hyper-parameters, with high time-consuming. This approach seeks rapid damage detection in arch dams under dynamic conditions, to prevent potential disasters, by utilizing the RBF-NNN to seamlessly integrate the dynamic elastic modulus (DEM) and modal parameters (such as natural frequency and mode shape) as damage indicators. To determine the dynamic characteristics of the arch dam, the JA sequentially optimizes an objective function rooted in vibration-based data sets. Two case studies of hyperbolic concrete arch dams were carefully designed using finite element simulation to demonstrate the effectiveness of the RBF-NN model, in conjunction with the Jaya algorithm. The testing results demonstrated that the proposed methods could exhibit significant computational time-savings, while effectively detecting damage in arch dam structures with complex nonlinearities. Furthermore, despite training data contaminated with a high level of noise, the RBF-NN and JA fusion remained the robustness, with high accuracy.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.1169-1172
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• 2007

This paper deals with the free vibrations of cantilever arches with constant volume. Its cross-sectional shape is the regular polygon whose depth is varied with the linear functional fashion. The non-dimensional differential equations governing the free vibration of such arch are derived and solved numerically for calculating the natural frequencies. As the numerical results, the effects of arch parameters such as side number of cross section, section ratio and aspect ratio on the natural frequencies are reported in figures.