• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.597-600
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• 2003

The development and maintenance of a sound bond are an essential requirements of concrete repair and replacement. The bond property of a bonded overlay to its substrate concrete during the lifetime is one of the most important performance requirements which should be quantified. A standard or a verified bond strength measurement method is required at field for screening, selecting materials and quality control for overlay or repair materials. This study compares the nipple pipe direct tensile test, flexural adhesion test, and core pull-off test with their test results. Substantial differences in the failure stresses of three test methods were attributed to their different geometries and loading conditions. From these comparison and investigation, core pull-off test was relatively good because the coefficient of variation values were about 2%. It would be suitable for use in-situ because of its simplicity and accuracy.

• 터널과지하공간
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• 제18권1호
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• pp.80-89
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• 2008

암반 내 작용하는 초기응력이 지하 암반 구조물의 안정성에 미치는 영향은 시공 심도가 깊어지고 단면 규모가 커질수록 증가하게 된다. 일반적으로 초기응력 측정은 암반 구조물의 설계단계에서 시공 예상지역 내 지표 수직공을 이용하여 수압파쇄법에 의해 이루어져 왔다. 그러나 조사단계에서 초기응력 측정이 이루어지지 않았거나 지형, 지질 특성상 과지압의 가능성이 있거나 또는 조사 과정에서 높은 수준의 초기응력장 분포가 확인된 지역에서는 시공의 안정성과 기존 설계의 적합성을 확인하기 위해서는 시공 현장의 지하 공간에서 상세 초기응력 측정을 수행하는 것이 바람직하다. 본 논문의 연구지역은 전라남도 OO시 남동부에 위치한 추가 석유 비축기지 건설현장으로 설계 전 상세 지반조사를 통해 측압계수 3.0 이상의 값을 가지는 과잉 수평응력장이 관찰된 지역이다. 본 연구에서는 비축기지 지하 건설 현장 내 굴착된 수벽터널용 공동에서 시추된 2개의 시험공에서 수압파쇄법에 의한 초기응력 측정을 시행하였다. 조사 범위는 지표로부터 약 $180m{\times}300m$ 심도구간이며 균열 조사에는 초음파 주사검층법을 적용하였다. 지표로부터 심도 200m 이상인 일부 조사 구간에서 측압계수 2.50 이상의 값을 가지는 큰 수평응력 성분들이 관찰되었고 전반적인 시험 결과는 설계 전 단계에서 수행된 조사 결과와 매우 유사한 양상을 나타내었다.

• 터널과지하공간
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• 제8권1호
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• pp.67-73
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• 1998

This paper presents the results of deformation measurement and numerical analysis carried out to study the behaviour of the rock mass around large underground oil storage caverns. Displacements during excavation have been monitored using borehole extensometers which had been installed before the excavation of caverns proceeded. Numerical analysis has been carried out to examine the three-dimensional behaviour of rock and the face advance effect. The input parameters for this analysis were determined from the results of laboratory and field tests. The deformation modulus of the rock mass was determined from plate loading test at the site and in-situ stresses were measured from the overcoring method with USBM deformation gauge. The results from this study gave a clear picture for three-dimensional behaviour of the rock mass, hence would be used for the optimum design.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2003년도 기술심포지움 논문집
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• pp.265-269
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• 2003

Sn(또는 SnAg)/Ni(P)와 Sn/Cu 계의 열사이클동안 형성되는 금속간화합물에 의해 유기되는 응력의 변화를 in-situ로 관찰하였다. Sn(또는 SnAg)/Ni(11.7P) 박막은 계면반응으로 인해 $Ni_3P$와 $Ni_3Sn_4$ 상이 형성되고 이때 인장응력이 발생하였으며, 한편, Sn(또는 SnAg)/Ni(3P) 박막의 계면반응에 의해서는 동일한 $Ni_3P$와 $Ni_3Sn_4$ 상이 형성됨에도 불구하고 압축응력이 발생하였다. SmAg를 사용할 때 형성되는 $Ag_3Sn$이 응력에 미치는 영향은 거의 없었다. Sn/Cu 박막의 경우는 계면반응 초기에는 인장응력이 발생하였고 어느 정도 이상 반응이 진전됨에 따라 압축응력이 발생하였고 최종적으로 $Cu_3Sn$ 상이 형성되었다. 초기의 인장응력은 계면에서 원자들의 intermixing 베 의한 것이고 압축응력은 Sn 방향으로 일방향 성장하는 금속간화합물 형성에 기인한다.

• 터널과지하공간
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• 제8권2호
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• pp.130-138
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• 1998

Comprehensive monitoring system for the safe and economical excavation of underground opening has been established by employing the 3 independent models each of which can i) predict the ultimate convergence, ii) assess the in-situ stresses and the elastic modulus of excavating rock, iii) calculate the time-dependent opening behavior with respect to the face advance rate and support pressure at the equilibrium state. Accuracy of each model has been verified through illustrative examples. The step-by-step procedures of comprehensive monitoring system for analyzing the rock behavior and the optimum support installation has been explained. The capability and applicability of this system to the practical excavation also has been discussed.

• 터널과지하공간
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• 제16권3호
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• pp.259-276
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• 2006

큰 초기응력을 받는 암반에서의 파괴 과정은 굴착경계에 평행하게 발생하는 응력 유도 균열에 의해 지배된다. 특히 지압의 절대크기가 암반 강도의 일정 비율 이상이 되면 응력 집중에 의한 암반의 취성 파괴를 유발하고, 이러한 현상은 터널 굴착 시 발생하는 파괴음과, 굴착면에 평행한 형태로 암편이 탈락하는 취성파괴 현상을 동반한다. Mohr-Coulomb과 같은 기존의 구성 모델은 일반적으로 마찰각과 점착력을 일정한 값으로 가정하므로, 점진적인 암반의 취성파괴 현상을 모사하기 어렵다. 본 논문에서는 일반적인 수치해석 코드에서 취성파괴를 잘 모의할 수 있는 것으로 알려진 CW-FS 모델을 사용하여 유류 저장공동 주변 암반에 대한 수치해석을 실시하고, 그 결과를 선형 Mohr-Coulomb 모델의 결과와 비교하였다. 또한 마찰각과 점착력 성분의 전단 소성변형률 한계를 변화시키면서 해석을 실시하여, 유류 저장공동에서 관찰된 취성파괴와 비슷한 양상을 보이는 해석 결과를 찾아보았다. 결과적으로 CW-FS 모델은 견고한 암반에서의 취성파괴를 모의하는데 있어 적절한 해석방법이라는 것을 알 수 있었다.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.78.1-78
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• 2003

An osmotin-like protein (CAOSMl) gene was isolated from pepper leaves infected with the avirulent strain Bv5-4a of Xmthomonas campestris pv. vesicatoria. The cDNA encodes a polypeptide of 250 amino acids with a molecular mass of 27, 361 Da. Its amino acid sequence is highly homologous to various osmotin-like proteins from other plant species. The CAOSMl gene expression was organ- and tissue-specifically regulated In pepper plants. The CAOSMl mRNA was intensely localized in the endodermis area of root tissue and in the phloem cells of vascular bundles of red fruit tissue, but not in leaf, stem, and green fruit tissues of healthy pepper plants. Infection by X. c. pv vesintoria, Colletotrichum coccodes, or Phytopkhora capsici iinduced CAOSMl transcription in the leaf or stem tissues. Expression of the CAOSMl gene was somewhat higher in the incompatible than the compatible interactions of pathogens with pepper. The CAOSMl mRNA was prevalently localized in the phloem cells of the vascular bundle of leaf tissues infected by C. coccodes. The CAOSMl gene was activated in leaf tissues by treatment with ethylene, methyl jasmonate, high salinity, cold acclimation and mechanical wounding, but not by abscisic acid (ABA) and drought. These results indicate that the pepper CAOSMl protein functions in response to Pathogens and some abiotic stresses in pepper plants

• Geomechanics and Engineering
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• 제21권2호
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• pp.187-200
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• 2020

In the current work, a series of three-dimensional finite element analyses have been conducted to investigate the behaviour of pre-existing single piles in response to adjacent tunnelling by considering the tunnel face pressures and the relative locations of the pile tips with respect to the tunnel. Via numerical modelling, the effect of the face pressures on the pile behaviour has been analysed. In addition, the analyses have concentrated on the ground settlements, the pile head settlements and the shear stress transfer mechanism at the pile-soil interface. The settlements of the pile directly above the tunnel crown (with a vertical distance between the pile tip and the tunnel crown of 0.25D, where D is the tunnel diameter) with a face pressure of 50% of the in situ horizontal soil stress at the tunnel springline decreased by approximately 38% compared to the corresponding pile settlements with the minimum face pressure, namely, 25% of the in situ horizontal soil stress at the tunnel springline. Furthermore, the smaller the face pressure is, the larger the tunnelling-induced ground movements, the axial pile forces and the interface shear stresses. The ground settlements and the pile settlements were heavily affected by the face pressures and the positions of the pile tip with respect to the tunnel. When the piles were inside the tunnel influence zone, tensile forces were induced on piles, while compressive pile forces were expected to develop for piles that are outside the influence zone and on the boundary. In addition, the computed results have been compared with relevant previous studies that were reported in the literature. The behaviour of the piles that is triggered by adjacent tunnelling has been extensively examined and analysed by considering the several key features in substantial detail.

• 한국터널지하공간학회 논문집
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• 제6권3호
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• pp.227-235
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• 2004

터널의 시공은 터널주변 지반에 구조적인 손상과 시공상의 손상을 불러일으킨다. 여기서의 구조적인 손상이란 터널굴착으로 인한 원지반응력의 교란으로 인하여 발생하는 것을 의미하며, 시공상의 손상이란 시공방법에 따른 주변지반의 손상을 의미한다. 본 논문에서는 원지반의 특성과 시공 중 손상을 고려할 수 있는 Hoek과 Brown 2002년도 공식을 이용하여 터널주변 탄 소성 영역에 작용하는 접선 및 반경방향의 응력 산정을 위한 식과 터널 주변 소성영역의 산정방법이 제시되었다. 또한, 매개변수분석을 통하여 암반의 등급, 무결암의 일축압축강도, 그리고 터널의 크기와 소성영역간의 상관관계를 조사하였으며, 기존의 연구에서 제안된 방법과의 비교를 통하여 본 연구에서 제안된 방법의 정확도를 검증하였다.

• Computers and Concrete
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• 제22권1호
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• pp.101-116
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• 2018

As one of the most important engineering structures, arch dams are huge constructions built with human hands and have strategical importance. Because of the fact that long construction duration, water supply, financial reasons, major loss of life and material since failure etc., the design of arch dams is very important problem and should be done by expert engineers to determine the structural behavior more accurately. Finite element analyses and non-destructive experimental measurements can be used to investigate the structural response, but there are some difficulties such as spending a long time while modelling, analysis and in-situ testing. Therefore, it is more useful to conduct the research on the laboratory conditions and to transform the obtained results into real constructions. Within the scope of this study, it is aimed to determine the structural behavior of arch dams considering experimentally validated prototype laboratory model using similitude and scaling laws. Type-1 arch dam, which is one of five arch dam types suggested at the "Arch Dams" Symposium in England in 1968 is selected as reference prototype model. The dam is built considering dam-reservoir-foundation interaction and ambient vibration tests are performed to validate the finite element results such as dynamic characteristics, displacements, principal stresses and strains. These results are considered as reference parameters and used to determine the real arch dam response with different scales factors such as 335, 400, 416.67 and 450. These values are selected by considering previously examined dam projects. Arch heights are calculated as 201 m, 240 m, 250 m and 270 m, respectively. The structural response is investigated between the model and prototype by using similarity requirements, field equations, scaling laws etc. To validate these results, finite element models are enlarged in the same scales and analyses are repeated to obtain the dynamic characteristics, displacements, principal stresses and strains. At the end of the study, it is seen that there is a good agreement between all results obtained by similarity requirements with scaling laws and enlarged finite element models.