• Structural Engineering and Mechanics
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• 제12권3호
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• pp.231-248
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• 2001

The three-dimensional behavior of confined concrete was investigated, including strength enhancement due to triaxial compressive stresses, lateral expansion, compression softening, cover spalling and post-peak ductility. A finite element program based on a nonlinear elasticity methodology was employed to evaluate the ability to model triaxial behavior of reinforced concrete (RC) by combining constitutive models proposed by several researchers. The capability of compression field based models to reproduce the softening behavior of lightly cracked confined concrete was also investigated. Data from tested specimens were used to evaluate the validity of the formulations. Good agreement with the experimental results was obtained.

• Coupled systems mechanics
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• 제13권2호
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• pp.115-132
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• 2024

This paper introduces an improved shear deformation theory for analyzing the buckling behavior of functionally graded plates subjected to varying temperatures. The transverse shear strain functions employed satisfy the stress-free condition on the plate surfaces without requiring shear correction factors. The material properties and thermal expansion coefficient of the porous functionally graded plate are assumed temperature-dependent and exhibit continuous variation throughout the thickness, following a modified power-law distribution based on the volume fractions of the constituents. Moreover, the study considers the influence of porosity distribution on the buckling of the functionally graded plates. Thermal loads are assumed to have uniform, linear, and nonlinear distributions through the thickness. The obtained results, considering the effect of porosity distribution, are compared with alternative solutions available in the existing literature. Additionally, this study provides comprehensive discussions on the influence of various parameters, emphasizing the importance of accounting for the porosity distribution in the buckling analysis of functionally graded plates.

• 한국지반신소재학회논문집
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• 제17권1호
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• pp.75-83
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• 2018

본 연구에서는 지반 내 공동에 대하여 긴급복구가 필요한 경우를 대상으로 개발된 포켓형 팽창재료의 거동특성을 분석하고자, 휠트래킹 시험을 통한 동적안정도 및 일축압축강도시험을 이용한 강도특성을 평가하였다. 휠트래킹 시험 결과, 높은 하중조건에서 포켓형 팽창재료로 복구된 지반은 모래지반에 비하여 침하량 증가율이 감소하였다. 즉, 포켓형 팽창재료는 재료의 강성으로 침하억제효과를 나타내는 것으로 확인되었으며, 이는 동적안정도 평가결과에서도 동일하게 나타났다. 휠트래킹 시험 전 후의 일축압축강도시험 결과로부터 공동 긴급복구용 포켓형 팽창재료는 복구된 지반 상부의 하중지지역할이 충분히 가능한 것으로 평가되었다.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1460-1470
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• 2015

This paper presents an approach to solve the long-term generation expansion planning problem of the restructured electricity industry using an agent-based environment. The proposed model simulates the generation investment decisions taken by a particular agent (i.e. a generating company) in a market environment taking into account its competitors’ strategic investment. The investment decision of a particular company is modeled taking into account that such company has imperfect foresight on the future system development hence electricity prices. The delay in the construction of new plants is also explicitly modeled, in order to compute accurately the yearly revenues of each agent. On top of a conventional energy market, several capacity incentive mechanisms including capacity payment and capacity market are simulated, so as to assess their impact on the investment promotion for generation expansion. Results provide insight on the investment cycles as well as dynamic system behavior of long-term generation expansion planning in a competitive electricity industry.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.47-54
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• 1999

A method is developed to include the effect of volume expansion in the description of the flame dynamics using G-equation. Line volume-source is used to represent the effect of the exothermic process of combustion with source strength assigned by the density difference between the burned and the unburned region. The present model provides good agreement with the experimental results by using realistic volume expansion ratio which was not reached in the previous researches. Including volume expansion, the flow predicts the same behavior of measured velocity field qualitatively. The flame propagation in varying flow field due to volume expansion provides a promising way to represent the wrinkled turbulent premixed flames in a numerically efficient manner.

• 한국산학기술학회논문지
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• 제8권2호
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• pp.348-353
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• 2007

본 연구에서는 중공형 섬유보강폴리머(Fiber Reinforced Polymer : FRP) 바닥판이 적용된 교량에 적합한 신축이음장치를 개발하고자 신축이음장치의 설계기준 및 특성을 분석하였다. 또한, 신축이음장치를 선정하는 기준이 되는 설계 신축량 산정법과 FRP바닥판 상세를 검토하여, 강콘크리트 거더 교량에 적용 가능한 FRP바닥판용 신축이음장치를 개발 제안하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.806-811
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• 2004

Currently, in the design criteria for the high speed railway bridges, the maximum distance between bridge expansion joint is limited to 80m using a continuous welded mil, in order to limit the additional stress in the rail due to the rail-bridge interaction. In the past study on the resonance effect of HSR train, it is known that the reduction of resonance and dynamic responses of bridge deck occurs at the specific expansion length of 28.05m and 46.75m. In this study, the stability of track structure on the HSR bridges with expansion length of 90m has checked by finite element method. And the track behavior including mil stresses and relative displacements are compared to the current state of track structures on the bridge system with 80m long expansion length.

• 한국주조공학회지
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• 제2권4호
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• pp.2-8
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• 1982

The behavior of sand and mold at high temperatures was generally agreed to importantly affect the quality of castings made. By changing water content through 2,4,6 and 8%, and bentonite content through 5,7,9 and 11%, specimens have been made according to the respective composition. Specimens have been subjected to hot compressive strength and thermal expansion at 400, 600, 800 and $1000^{\circ}C$ respectively. The results obtained were as follows ; 1. At each temperature, thermal expansion decreased and hot compressive strength increased with the increase in water content. 2. After thermal expansion was peaked at approximately $1000^{\circ}C$ the contraction and maximum hot compressive strength appeared. 3. At each temperature, maximum hot compressive strength appeared 2%, 4,6% and 8% water content for 7%, 9% and 11% bentonite content respectively. 4. When 2% $H_2O$ was added, though bentonite content was increased, hot compressive strength did not rarely change. 5. Until the thermal expansion was completed the required time was 15-18 minutes at $400^{\circ}C$ and $600^{\circ}C$, and 10-13 minutes at $800^{\circ}C$. At $1000^{\circ}C$, the required time was 7-9 minutes in order to gain the maximum expansion, after that, contraction proceeded during 3-4 minutes before expansion was completed.

• 한국도로학회논문집
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• 제17권2호
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• pp.13-20
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• 2015

PURPOSES: This paper describes the expansion caused by the alkali-aggregate reaction (AAR) in concrete pavement currently in service. It also discusses the effects of joints installed to release the stress induced by the AAR expansion. METHODS: The expansion effect on concrete pavement was verified by a visual inspection and long-term measurement of the joint width of a cut-section. The behaviors of 16 newly installed joints were monitored as part of the investigation and long-term monitoring was carried out for three years after cutting. RESULTS: The behavior of a bridge was affected when AAR occurred in the connected pavement. The newly installed joints shrank in the longitudinal direction of the bridge after cutting. The width of the joints decreased over the six months after cutting. A large portion of the joint width (8.5cm) was found to have closed nine months after cutting. It had ultimately shrunk by about 92 percent when the final measurement was taken. CONCLUSIONS : The expansion of the pavement due to AAR was quantitatively described by visual inspection and the long-term monitoring of the newly cut joints. However, the width of the new joints decreased over the six to nine months after cutting. Additional research should be conducted to determine a means of controlling the expansion due to AAR in the pavement.

• 한국자동차공학회논문집
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• 제21권2호
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• pp.154-158
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• 2013

Expansion joint has been utilized in many areas including automotive bellows for exhaust system. Usage of expansion joint has been increased due to its inherent flexibility and excellent anti-vibration property. Simple shape of expansion joint is modeled to understand the behavior of joint system. 27 design cases using 3 design factors with 3 levels are constructed by design of experiment. Each case is simulated to find the most influential design factors. Response for this study, maximum stress in the expansion joint, has been used to determine main design factors of joint. Among the 3 design factors, factor B has affected greatly a response in the formation of optimum shape of joint. Also, interaction factor, $A{\times}B$, has also showed its influence to the response of joint. This study showed that design of experiment combined with finite element analysis could be used in the design decision process effectively in the design of expansion joint.