• 산업기술연구
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• 제22권B호
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• pp.199-209
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• 2002

This research is experimental thesis to prepare the structural safety of the upper bridge for support type on tunnel and the effect of settlement. Unit weight test and uni-axial compression test have been performed to simulate the physical property of foundation on the tunnel. Tunnel model of slip form type for centrifuge model has been developed to performed the tunnel excavation while field stress is activated. And the support type of tunnel such as umbrella arch method and large diameter steel pipe reinforce method has been tested for the centrifuge model. After the analysis of experiment, results show that internal displacement of large diameter steel pipe reinforce method is smaller than that of the umbrella arch method.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.581-588
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• 2006

Now, a long span and special types of steel deck bridges like as suspention or cable state bridges are increasing and Guss Asphalt used in pavement. But Guss Asphalt may caused severe stress and displacement of the bridge as it is treated using very high temperature ranging from $220^{\circ}C\;to\;260^{\circ}C$. In this paper, a series of numerical tests of a steel deck box arch bridge were conducted to estimate the thermal effect of a steel deck bridge according to temperature changes.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.846-851
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• 2003

The differential equations governing free, in-plane vibrations of non-circular arches with non-uniform cross-section, including the effects of rotatory inertia, shear deformation and axial deformation, are derived and solved numerically to obtain frequencies. The lowest four natural frequencies are calculated for the prime parabolic arches with hinged-hinged, hinged-clamped, and clamped-clamped end constraints. Three general taper types for rectangular section are considered. A wide range of arch rise to span length ratios, slenderness ratios, and section ratios are considered. The agreement with results determined by means of a finite element method is good from an engineering viewpoint.

• PNF and Movement
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• 제20권2호
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• pp.167-177
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• 2022

Purpose: Pes planus is a common foot deformity that involves the loss of the medial longitudinal arch. The medial longitudinal arch deformity is usually asymptomatic; however, it can lead to an increased risk of pain and injury. Low-Dye taping is designed to treat plantar heel pain and pes planus. However, low-Dye taping is relatively complex, and a considerable amount of time is required to apply the tape correctly. The purpose of this study was to compare the acute effect of two different types of taping (low-Dye taping and modified Mulligan taping) on arch reformation, plantar pressure, and gait characteristics in participants with asymptomatic flexible pes planus. Methods: Twenty subjects (9 males and 11 females; mean age = 21.95 years) with asymptomatic flexible pes planus voluntarily participated in this study. Arch reformation was evaluated using navicular height measurements. Changes in plantar pressure distribution were measured using BioRecue equipment. Gait parameters were measured using spatiotemporal data collected during consecutive gait cycles using a G-WALK device. One-way analysis of variance was used to compare the three different conditions (i.e., bare foot, low-Dye taping, and modified Mulligan taping) for each variable. Results: Navicular height was significantly increased in subjects who underwent the two types of taping compared to those who experienced the bare foot condition. The plantar pressure was significantly shifted to the posterolateral area after modified Mulligan taping compared with the bare foot condition. There were no significant differences in the gait parameters. Conclusion: The findings of this study indicate that modified Mulligan taping has a similar effect to low-Dye taping, and modified Mulligan taping is a simpler method than low-Dye taping.

• 생물환경조절학회지
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• 제2권2호
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• pp.89-98
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• 1993

본 연구에서는 일반농가에서 시설내 환경이 불량한 아치형 파이프하우스를 간이시설로 이용하고 있어 시설내 환경이 개선된 간이시설을 개발하여 작물생장반응을 구명코자 톱날형과 개량아치형, 관행아치형의 시설형태와 노지로 구분, 시험을 실시하여 연구결과를 요약하면 다음과 같다. 1. 개량아치형은 관행아치형에 비해 최고 4$^{\circ}C$의 온도가 낮아졌고, 톱날형은 1$^{\circ}C$이상 낮아 시설내 환경이 개선되었다. 2. 지하부 환경에서 관행아치형에 비해 잠열냉각+배수개선 처리는 1.3$^{\circ}C$가 낮고, 배수개선 처리는 0.9$^{\circ}C$가 낮게 나타나 잠열효과를 1$^{\circ}C$이상 보았다. 3. 톱날형은 하우스파이프를 지주겸용으로 설치하여 성력화면에서 가장 우수하였으며 환기를 위한 인력이 필요치 않아 노동력을 절감할 수 있는 시설로 개발되어졌고, 개량아치형은 환기를 위한 노동력은 필요하였으나 하우스파이프를 지주겸용으로 설치하였으므로 관행아치형에 비해 성력화되었다. 4. 토마토 상품과율은 개량아치형이 4,897kg/10a로 가장 많았고 관행아치형이 그 다음 순이었으며 광합성과 직접적인 관계가 되는 엽면적은 톱날형이 다른 형태보다 가장 넓었다. 5. 수량 및 상품성을 높이기 위해서는 환기면적이 넓은 개량아치형이 간이시설로써 적당하였고, 지하부 환경개선 효과는 톱날형의 잠열냉각+배수개선 방법이 좋았으며, 개량아치형과 관행아치형은 배수개선이 효과적이었다. 6. 톱날형, 개량아치형 간이시설은 성력화되고 시설내 환경이 개선되어졌으며, 관행아치형 시설형태를 좀더 발전시켜야 할 것으로 사료된다.

• Structural Engineering and Mechanics
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• 제58권2호
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• pp.243-257
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• 2016

The aim of this study is to investigate the seismic resistance of dry stone arches under in-plane seismic loading. For that purpose, several numerical analyses were performed using the combined finite-discrete element method (FDEM). Twelve types of arches with different ratios of a rise at the mid-span to the span, different thicknesses of stone blocks and different numbers of stone blocks in the arch were subjected to an incremental dynamic analysis based on excitation from three real horizontal and vertical ground motions. The minimum value of the failure peak ground acceleration that caused the collapse of the arch was adopted as a measure of the seismic resistance. In this study, the collapse mechanisms of each type of stone arch, as well as the influence of the geometry of stone blocks and stone arches on the seismic resistance of structures were observed. The conclusions obtained on the basis of the performed numerical analyses can be used as guidelines for the design of dry stone arches.

• Structural Engineering and Mechanics
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• 제39권4호
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• pp.521-539
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• 2011

Jilin highway concrete bridge is located in the center of Jilin City, which is positioned in the middle part in Jilin Province in the east north of China. This bridge crosses the Songhua River and connects the north and the south of Jilin City. The main purpose of damages inspection of the bridge components is to ensure the safety of a bridge and to identify any maintenance, repair, or strengthening which that need to be carried out. The damages that occur in reinforced concrete bridges include different types of cracks, scalling and spalling of concrete, corrosion of steel reinforcement, deformation, excessive deflection, and stain. The main objectives of this study are to inspect the appearance of Jilin highway concrete bridge and describe all the damages in the bridge structural members, and to evaluate the structural performance of the bridge structure under dead and live loads. The tests adopted in this study are: (a) the depth of concrete carbonation test, (b) compressive strength of concrete test, (c) corrosion of steel test, (d) static load test, and (e) dynamic load test. According to the damages inspection of the bridge structure appearance, most components of the bridge are in good conditions with the exception arch waves, spandrel arch, deck pavement of new arch bridge, and corbel of simply supported bridge which suffer from serious damages. Load tests results show that the deflection, strain, and cracks development satisfy the requirements of the standards.

• Coupled systems mechanics
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• 제10권1호
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• pp.1-19
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• 2021

Composite nature of the masonry structures in general causes complex and non-linear behaviour, especially in intense vibration conditions. The presence of different types and forms of structural elements and different materials is a major problem for the analysis of these type of structures. For this reason, the analysis of the behaviour of masonry structures requires a combination of experimental tests and non-linear mathematical modelling. The famous UNESCO Heritage Old Bridge in Mostar was selected as an example for the analysis of the global behaviour of reinforced stone arch masonry bridges. As part of the experimental research, a model of the Old Bridge was constructed in a scale of 1:9 and tested on a shaking table platform for different levels of seismic excitation. Non-linear mathematical modelling was performed using a combined finite-discrete element method (FDEM), including the effect of connection elements. The paper presents the horizontal displacement of the top of the arch and the failure mechanism of the Old Bridge model for the experimental and the numerical phase, as well as the comparison of the results. This research provided a clearer insight into the global behaviour of stone arch masonry structures reinforced with steel clamps and steel dowels, which is significant for the structures classified as world cultural heritage.

• Composites Research
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• 제36권3호
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• pp.173-179
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• 2023

The sandwich structure, consisting of a core and a face sheet, is used for lightweight structural application. Generally, cellular structures like honeycomb, foam, and lattice structures are utilized for the core. Among these, lattice structures have several advantages over other types of structures. In other studies, curved lattice structures were reported to have higher mechanical properties than straight structures by converting shear stresses acting on the structure into compressive stresses. Moreover, the addition of vertical struts can have a positive effect on the mechanical properties of the lattice structure. For the purpose, two lattice structures with Circle Arch (CC) and Circular Arch with a vertical column (CC_C) were studied, which were fabricated by using selective laser sintering was conducted. The result showed that CC_C has dramatic performance improvements in specific strength, modulus, and strain energy density compared to CC, confirming that vertical struts played a significant role in the lattice core. Finite element analysis was employed to determine the cause of the stress behavior of CC and CC_C. This study is expected to help design structurally superior lattice cores and sandwich structures.

• 대한토목학회논문집
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• 제34권1호
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• pp.29-47
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• 2014

내구성과 미관성이 우수한 석조 아치교량은 단경간 교량으로서 가장 오래되고 경험적으로 시공되었던 구조물로서 유럽에서는 지금까지도 현장에 시공되고 있으며, 이에 대한 활발한 연구가 진행되고 있다. 그러나 국내에서는 시공법의 비효율성과 비경제성으로 인해 교량 목적으로 시공되는 경우는 거의 없는 상태이다. 따라서 본 연구에서는 기존 연구자들이 제안한 시스템에서 구조성능의 향상이 가능한 보강된 이음부의 접합방법을 제안하였다. 제안된 이음부는 횡방향 루프이음과 종방향 보강근을 적용한 형식으로 프리캐스트 콘크리트 블록으로 이루어진 아치에 적용하여 실험을 통해서 구조적 성능을 평가하였다. 실험결과, 보강된 이음부는 소량의 보강근으로도 블록 상호 간의 상대변위와 힌지거동을 억제시켜 기존의 형식보다 충분한 내력을 향상시킬 수 있을 것으로 판단된다.