• Geomechanics and Engineering
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• 제11권4호
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• pp.515-530
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• 2016

In this paper, five different quantitative parameters were proposed for the characterization of the primary roughness which is the component of surface morphology that prevails during large strike-slip faults of more than 50 m. These parameters are mostly the anisotropic properties of rock surface morphology at various scales: (i) coefficient ($k_a$) and degree (${\delta}_a$) of apparent structural anisotropy of surface; (ii) coefficient ($k_r$) and degree (${\delta}_r$) of real structural anisotropy of surface; (iii) surface anisotropy function P(${\varphi}$); and (iv) degree of surface waviness ($W_s$). The coefficient and degree of apparent structural anisotropy allow qualifying the anisotropy/isotropy of a discontinuity according to a classification into four classes: anisotropic, moderately anisotropic/isotropic and isotropic. The coefficient and degree of real structural anisotropy of surface captures directly the actual surface anisotropy using geostatistical method. The anisotropy function predicts directional geometric properties of a surface of discontinuity from measurements in two orthogonal directions. These predicted data may subsequently be used to highlight the anisotropy/isotropy of the surface (radar plot). The degree of surface waviness allows qualifying the undulation of anisotropic surfaces. The proposed quantitative parameters allows their application at both lab and field scales.

• 한국지반공학회논문집
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• 제34권8호
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• pp.5-14
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• 2018

쇄설성 퇴적암의 입자 크기는 암석을 구분하는 기준인 동시에 이방성의 원인이 된다. 이방성은 암석의 강도와 풍화에 영향을 미치는 주 원인 중 하나이다. 경상분지의 영주, 대구, 부산 지역에 분포하는 쇄설성 퇴적암과 화성암을 대상으로 대자율타원체를 결정하고 이방성정도와 모양지수를 통해 이방성을 분석하였다. 외력의 영향이 거의 없는 호성환경에서 퇴적된 사암의 이방성정도는 1.03 이하였다. 단층의 영향을 받은 암석은 1.06, 단층암은 1.14 이상의 이방성 정도를 보였다. 암석의 자기적 이방성은 단층으로부터 거리가 멀어질수록 이방성 정도가 감소하였다. 세립질의 입자로 구성된 이암과 셰일은 일차퇴적구조인 층리가 박층으로 발달하며 이로 인해 단층암과 유사한 크기의 이방성을 보였고 대자율타원체의 모양지수도 편원형을 보였다. 실험 결과로부터 쇄설성퇴적암 중 신선한 이암과 셰일은 단층암과 유사한 이방성을 가지므로 이들 암반과 관련된 구조물의 설계, 시공, 유지관리에서 주의가 필요하다.

• 소성∙가공
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• 제27권5호
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• pp.301-313
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• 2018

In this paper, tensile test was performed on pure titanium sheet (CP Ti sheet) with HCP structure in each direction to evaluate mechanical and surface properties and analyze microstructural changes during plastic deformation. We also evaluated forming limits of Ti direction in dome-type punch stretching test using a non-contact three-dimensional optical measurement system. As a result, it was revealed the pure titanium sheet has strong anisotropic property in yield stress, stress-strain curve and anisotropy coefficient according to direction. It was revealed that twinning occurred when the pure titanium sheet was plastic deformed, and tendency depends differently on direction and deformation mode. Moreover, this seems to affect the physical properties and deformation of the material. In addition, it was revealed the pure titanium sheet had different surface roughness changes in 0 degree direction and 90 degree direction due to large difference of anisotropy, and this affects the forming limit. It was revealed the forming limit of each direction obtained through the punch stretching test gave higher value in 90 degree direction compared with forming limit in 0 degree direction.

• 한국지반공학회지:지반
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• 제2권3호
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• pp.27-36
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• 1986

뒷채움 다짐한 옹벽에 저해 침투빙가 주동토압에 미치는 영향을 관찰하기 위하여 책험과 이론해석에 의하여 연구가 수행되었다. 다짐방법이 모래의 투빙성에 미치는 영향을 관찰하기 위하여 특별히 고안된 정수두 투수시험장치와 전기전도도 측정법에 의하여 실험이 행해졌다. 실험결과, 다짐방상에 직각인 방향과 평행한 방향의 투수계수의 비(kz/ky)는 공소비와 반대수방안지에서 직선관계로 보이고, 상대밀도가 90% 이상에서는 kz/ky의 값이 2-4로 나타났다. 이 때 다짐방법은 투수계수에 별다른 영향을 주지 않았으며, 굵은 모래보다 가는 모래에서 이방성이 크게 나타났다. 이방성 침투가 주동토압에 미치는 영향을 관찰하기 위하여 확장된 Gray 이론에 실험결과를 적용하여 보았다. kz/ky의 값이 클수록 주동토압의 크기는 작아지고, 벽면마찰의 영향은 크지 않았다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.729-736
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• 2000

For nonhomogeneous and anisotropic rocks such as schist, shale, etc, a method to determine the anisotropic elastic constants was proposed. Many authors have investigated in detail the behavior elastic constants of anisotropy rocks(Pinto 1970, Amadei 1983, 1992, Amadei & Savage 1989). They concluded that equations of elastic constants E$_1$, E$_2$ and G$_2$ can be derived from the measured strains in arbitrary three directions. And, modulus of elasticity varies according to the inclination of discontinuity in specimens. If we attach three strain gages in accordance with the directions of anisotropy on the rock specimen under uni-axial compression and diametral compression tests, anisotropy elastic constants can be determined by these equations. With this method, the degree of anisotropy will be easily evaluated by simple laboratory test. This paper presents the results of elastic constants due to the angle of bedding planes of anisotropic rock, such as shale, in uni-axial compression and diametral compression tests

• Nuclear Engineering and Technology
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• 제51권6호
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• pp.1525-1531
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• 2019

The indigenous nuclear power program of India is based mainly on a series of Pressurised Heavy Water Reactors (PHWRs). A burst correlation for Indian PHWR fuel claddings has been developed and empirical burst parameters are determined. The burst correlation is developed from data available in literature for single-rod transient burst tests performed on Indian PHWR claddings in inert environment. The heating rate and internal overpressure were in the range of 7 K/s-73 K/s and 3 bar-80 bar, respectively, during the burst tests. A burst criterion for inert environment, which assumes that deformation is controlled by steady state creep, has been developed using the empirical burst parameters. The burst criterion has been validated with experimental data reported in literature and the prediction of burst parameters is in a fairly good agreement with the experimental data. The burst criterion model reveals that increasing the heating rate increases the burst temperature. However, at higher heating rates, burst strain is decreased considerably and an early rupture of the claddings without undergoing considerable ballooning is observed. It is also found that the degree of anisotropy has significant influence on the burst temperature and burst strain. With increasing degree of anisotropy, the burst temperature for claddings increases but there is a decrease in the burst strain. The effect of anisotropy in the ${\alpha}$-phase is carried over to ${\alpha}+{\beta}$-phase and its effect on the burst strain in the ${\alpha}+{\beta}$-phase too can be observed.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.755-758
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• 2005

The mechanism responsible for liquid crystal (LC) alignment on solid substrates treated with mechanical rubbing or polarized UV is not understood. The results of x-ray reflectivity study of LC alignment on a large number of different alignment layers show that the anisotropy in the surface roughness of the substrate completely determines the LC alignment. The anchoring energy depends on the degree of roughness anisotropy and chemical interactions between the substrate and LC molecules.

• 터널과지하공간
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• 제5권4호
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• pp.318-322
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• 1995

For transversely isotropic rocks such as schist, shale, etc, a method to determine the anisotropic elastic constants was proposed. Theoretically, equations of elastic constants E1, E2, and G2 can be derived from the measured strains in arbitrary three directions. If we attach three strain gages in accordance with the directons of anisotropy on the rock specimen under uni-axial compression, anisotropic elastic constants can be determined by these equations. With this method, the degree of anisotropy of transversely isotropic rocks will be easily evaluated by simple laboratory test.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.150-155
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• 2003

Fractures in the form of micro cracks are commonly found in natural rocks. A rock behaves in a complex way due to fracture; in particular, the anisotropic strength of a rock material is significantly influenced by the presence of these fractures. Therefore, it is essential to understand the failure mechanism of a fractured rock. In this study, a fractured rock is formulated in terms of fabric tensor based on geometric and mechanical simplifications. In this way, position, density and shape of fractures can be determined by the fabric tensor so that rocks containing multi-fractures can successfully be modeled. Also an index to evaluate the degree of anisotropy of a fractured rock is proposed. Hence, anisotropic strength of a rock containing fractures under uniaxial compression condition is estimated through a series of numerical analyses for the multi-fractured model. Numerical investigations are carried out by varying the fracture angle from $0^{\circ}\;to\;90^{\circ}$ and relationship between uniaxial compression strength and the degree of anisotropy is investigated. By comparing anisotropic strength of numerical analysis with analytic solution, this study attempts to understand the failure mechanism of rock containing fractures.

• The Korean Journal of Ceramics
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• 제6권4호
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• pp.405-407
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• 2000

Polycrystalline films of Ni- and Co-ferrites films are prepared from aqueous solution at $90^{\circ}C$ by ferrite plating, which are subjected to Fe$^57$ conversion electron Mossbauer spectroscopy in backscatter mode. The average angle of Fe spins relative to the film plane is evaluated as 18 degree and 82 degree for the Ni- and Co-ferrite films, respectively, indicating a prominent magnetic anisotropy parallel and perpendicular to the film plane. It was also verified by the magnetization measurements.