• Proceedings of the Korean Society of Precision Engineering Conference
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• 1991.11a
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• pp.110-115
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• 1991

일반적으로 거의 모든 재료의 기계적인 물성치들이 여러가지 하중조건에 의해 변화하는데 그 중 탄성계수는 하중속도, 온도, 재료의 특성에 따라 변화한다. 지금까지 국내에서의 연구동향을 보면 하중속도가 탄성계수에 미치는 영향에 대한 연구보고는 미약한 실정이다.(중략)

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.171-180
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• 2008

This study was conducted to analyze the curling behavior of concrete slabs on grade under temperature loading through the laboratory tests and to investigate the effects of the support conditions of underlying layers on the curling behavior of the slab on grade systems. For the laboratory tests, the concrete slabs were fabricated and the temperature measurement sensors were installed. The temperature loading was applied intentionally and the time histories of the vertical displacements of the slab at several different positions were measured. One-layered underlying layers were made using different materials and different thicknesses. Two-layered underlying layers were also made to have the same composite stiffness each other, but the material of the upper layer was designed to be different The experimental analysis results showed that the trend of the displacement time histories of the slab was basically the same as that of the temperature gradient time histories. The characteristics of the curling behavior of the slab were analyzed by separating the regions of curling up and curling down. The difference in the vertical displacements at the center and comer decreased as the stiffness of the underlying layer became larger, and the upper layer's material of the underlying layers affected the curling behavior of the slab.

• Journal of Korean Society of Steel Construction
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• v.16 no.1 s.68
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• pp.103-111
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• 2004

This paper dealt with the local buckling of H-beams investigated mainly using the parameters of load ratios. load conditions, and support boundary condition considering predicted uniformly elevated temperatures. The physical properties of the material at elevated temperatures followed EC3 Park 1.2. The local buckling of the plates in steel beams show that they are governed by the yield stress or the critical stress of the steel plates according to the ratios of b/tf, d/tw. The evaluation of uniformly heated steel beams on the local buckling considered the stress and moment ratios to the LRFD.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1992.06a
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• pp.66-70
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• 1992

고전적 동수압유체윤활이론은 유막 내의 점성을 일정하다고 가정한다. 유막의 전개방향이나 유막두께방향으로의 온도변화를 결정하는 데 이론적으로나 실험적으로 어려움이 있으므로 이 간소화는 베어링설계에 널리 사용되었다. 그러나 많은 실험적 관찰은 등점성 동수압유체윤활이론은 유막내의 온도상승이나 하중지지용량의 감소를 설명하지 못함을 입증하였다. Fogg는 평행한 추력베어링이 하중을 지지할 수 있음을 발견하였으며 이 fogg의 효과는 동수압 유체윤활이론의 예측과 반대되는 것이고 Thermal wedge라는 개념으로 설명되었다. Hunter와 Zienkiewicz는 유막내에서의 에너지 균형에 관한 이론적 연구를 소개하였고, 온도효과와 이로 인한 유막두께 방향의 점도 변화는 무시될 수 없다는 결론을 내렸다. 본 해석에서는 압력분포를 근사해법으로 구하여, 선지지되는 2차원 틸팅패드 트러스트베어링에서 패드의 탄성 변형을 고려한 열유체윤활해석과 고려하지 않은 얼유체윤활 해석의 결과를 서로 비교함으로서 패드의 변형이 유막의 압력장과 온도장에 미치는 영향과 패드두께의 변화가 유막의 온도장과 압력장에 미치는 영향을 고찰하고자 한다.

• Journal of Korean Society of Steel Construction
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• v.22 no.6
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• pp.581-588
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• 2010

Recently the requirements of the buildings built with structural steel were increased in terms of structural stabilities and fire resistance at severe fire conditions. To meet the building regulations of fire resistance, a fire design is needed. This is of a prescriptive method and a performance engineering based method. Recently a simple calculation method as one of performance based engineering method is very popular because of its ease for an application in building built with structural steel. But, in Korea the performance based engineering method is not allowed yet. Thus it is needed to make a guideline for the performance based engineering method. The purpose of this study is to establish the limit temperature derived from structural beams made with both a H-section and a H-section filled with concrete at the web and derived the limit temperatures from beams made with H-sections and found out that the limit temperatures from two kinds of specimens depended on the applied loads and the specimens filled with the concrete represented 3 hour fire resistance in the range of 80%, 60%, and 50% of the maximum load.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.157-164
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• 2010

This research was conducted to analyze the behavior of Single-PTAS (Single Post-Tensioned Approach Slab) under tensioning and environmental loads by performing field tests when the demonstration Single-PTAS was being constructed. The temperature measurement sensors were installed at different depths, and the displacements in the approach slab under environmental loads and tensioning were measured using displacement transducers. As an experimental result, an abrupt change in the longitudinal displacement due to tensioning was not observed. The daily temperature change in the approach slab was negligible where the depth is over about 35cm. The temperature gradient in the approach slab adjacent to bridge was smaller than that adjacent to pavement. The patterns and magnitudes of vertical displacements were directly related to the temperature gradient at the measuring location. The behavior of Single-PTAS was very similar to that of concrete pavement. Therefore, a new design methodology for approach slabs is needed to include the pavement concept and to overcome drawback of current design procedures based on the simple beam concept.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.5
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• pp.305-311
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• 2019

In this study, we examined the proper spacing between the expansion joints according to the temperature load of the inter-modal terminal platform infrastructure to implement a new inter-modal automated freight transport system, which we intend to introduce in Korea. To review the proper expansion joint spacing of the terminal platforms, we set the maximum expansion joint spacing according to the regional temperature changes using the equation proposed by the Federal Construction Council (FCC) of the United States. Then, the maximum displacement value, which was calculated through the structural analysis program, and the limit of the horizontal displacement of the building structure were compared. The proper expansion joint spacing was selected as the slab length at which the maximum displacement of the structure, due to temperature changes, was below the horizontal displacement limit. Based on the application of maximum expansion joint spacing for each region calculated through the FCC's suggestion, the maximum displacement that could occur within the limit of the lateral displacement of the structure was determined.

• Korean Journal of Materials Research
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• v.10 no.4
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• pp.305-311
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• 2000

Applicability of crack arrest load measured from the Charpy V-notch impact test has been investigated to predict the fracture toughness of nuclear reactor pressure vessel (RPV) steels (ASME SA508 Cl.3). The temperature dependence of the crack arrest load was well described by the type of exponential function characterized by an index temperature at which the crack arrest load is 2kN. The specific index temperature, which also well correlated with $T_{NDT}\;and\;T_{41J}$ is expected to be representative index temperature characterizing the crack arrest fracture toughness of RPV steels. Also, the crack arrest load correlated well with the stable crack length measured from the fracture surface. From the measurements of the crack arrest load and the stable crack length, the lower bound fracture toughness, $K_{Ia}$ of RPV steels could be predicted with sufficient accuracy.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.296-301
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• 1996

이 연구의 목적은 원주방향 균열을 가진 페라이틱 배관의 파괴거동을 실험적으로 평가하는데 있다. 한계하중방법, SC.TNP 방법, R6방법, 그리고 ASME Code방법과 같은 여러 파괴거동 평가 방법의 타당성이 PWR 운전조건(압력:15.5MPa, 온도:228$^{\circ}C$)하에서의 직경 16인치의 대규모 배관파괴실험을 통해 조사된다. 모사지진하중, 단일주파수 사인함수하중, 정하중과 같은 여러 가지 형태의 하중이 배관의 하중지지능력에 미치는 영향이 조사된다. 또한 엘보우부위와 직관부의 영향과 표면균열 및 관통균일의 영향 등도 함께 조사된다. 결과는 다음과 같다. (1) 표면균열을 가진 배관의 파괴거동은 한계하중방법과 SC.TNP 방법에 의해 잘 예측할 수 있다. 반면 관통균열의 경우는 한계하중방법에 의해 잘 예측된다. (2) 모사지진하중하에서는 단일주파수 사인함수하중이나 정하중 하에서 보다 하중지지능력이 크게 예측된다. (3) 엘보우부위와 직관부, 관통균열과 표면균열 사이에 파괴거동에 대한 큰 차이는 없다.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.541-546
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• 1998

증기 제트 응축에서 발생하는 응축하중을 실험적으로 고찰하였다. 네 가지 서로 다른 직경의 노즐 (5, 10, 15, 20mm) 과 증기분사기를 응축실험에 사용하였으며, 증기 질량유속과 물온도를 변화하면서 동압을 측정하였다. 실험결과에 의하면 압력파의 진폭은 노즐 직경이 작을수록 작았다. 한편 압력파의 진폭은 일반적으로 물온도가 증가할수록 증가하나 물온도가 어느 한도 이상으로 증가하면 오히려 감소하는 경향을 보였다. 그러나 물온도가 아주 높고 증기 질량유속이 큰 경우에는 불안정한 압력파가 발생할 가능성이 관찰되었다.