• Tunnel and Underground Space
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• v.15 no.6 s.59
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• pp.391-399
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• 2005

In this study, stress difference between isotropic and transversely isotropic rock mass, and planar principal stresses at the periphery of the tunnel in the rock with various ratio of anisotropy were determined theoretically. Stress differences between isotropic and anisotropic calculations at crown. side walls and floor of a tunnel with assumed stress states were analyzed and compare each other by $FLAC^{2D}$, a finite differential element method. As a result, magnitude and direction of principal stresses in the case of ignoring anisotropy were different from those of anisotropic cases, whatever the stress state was. Stress difference increased as the ratio of anisotropy increased. Direction or anisotropy affected stress difference, especially in the cases of anisotropic directions of $45^{\circ}\;and\;135^{\circ}$ of counterclockwise from x direction.

• The Journal of the Korea Contents Association
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• v.8 no.11
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• pp.1-9
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• 2008

Thanks to the multimedia technology development, it is possible to show image representations in high quality and to process images in various ways. Anisotropic diffusion as an effective diffusion filtering among many image preprocessing methods and postprocessing methods is used in reduction of speckle noises of ultrasound images, image restoration, edge detection, and image segmentation. However, the conventional anisotropic diffusion based on a cross-kernel causes the following problems. The problem is the concentration of edges in the vertical or horizontal directions. In this paper, a new anisotropic diffusion transform based on directions of gradient is proposed. The proposed method uses the eight directional square-kernel which is an expanded form of the cross-kernel. The proposed method is to select directions of small gradient based on square-kernel. Therefore, the range of proposed diffusion is selected adaptively according to the number of the directions of gradient. Experimental results show that the proposed method can decrease the concentration of edges in the vertical or horizontal directions, remove impulse noise. The image in high quality can be obtained as a result of the proposed method.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.3
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• pp.178-182
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• 1981

쉘이 복합재로 제작되었거나 보강재를 사용하였을때에는 쉘요소의 역학적 특성은 방향성을 가지게 된다. 이 논문에서는 선형관계식을 사용하여 동적 표면가동을 받는 이방성원통쉘의 안정성을 고려하여 다루었다. 재료의 이방성을 고려하여 3방향 즉, 축방향, 둘레방향 및 반경향의 실성항이 포함된 운동방장실을 유도하였다. 동적 안전성의 해석은 Bolotin 의 방법을 따랐으며 근사해를 행렬식행으로 제시하였다. 수직열로 외압을 받는 원통쉘의 좌단을 다루었으며 본 이론과 고전이론 사이의 차이점을 검토하였다.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1023-1025
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• 2005

이방성 전기강판으로 제작되어진 전기기기의 보다 정확한 수치적인 해석을 위해서는 이방성 전기강판의 인가자계방향에 따른 정확한 자계특성 측정이 필요하다. 이 논문에서는 개발되어진 2방향 자계인가 형 싱글시트 테스터를 이용하여 이방성 전기강판의 인가자계방향에 따른 자계특성을 측정하였다. 실험을 통하여 방향성 전기강판의 rolling direction과 transverse direction에 대하여 각각 1.8[T]와 1.3[T]까지 측정할 수 있었다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.172-175
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• 2001

이 연구에서는 5개의 시추공에 대한 양수시험을 실시하여 대수층의 수리학적 이방성과 지하수의 주 유동방향을 규명하고자 하였다. 코아검층 및 초음파주사검층을 통해 각각의 공에 대한 균열방향을 결정하고 이를 토대로 통합해본 결과 크게 세 방향의 균열군이 집중성을 보였다. 가장 빈도가 높은 균열의 방향은 N0$^{\circ}$~40$^{\circ}$E/30$^{\circ}$~50$^{\circ}$SE 그리고 N30$^{\circ}$~ 80 $^{\circ}$W/20$^{\circ}$~50$^{\circ}$ NE이 방향이 함께 나타났으며 두 번째 균열의 방향은 N0$^{\circ}$ ~50$^{\circ}$E/60$^{\circ}$ ~80$^{\circ}$NW로 나타났다. 세 번째 방향은 N30$^{\circ}$~50 $^{\circ}$W/70$^{\circ}$~80$^{\circ}$SW방향의 균열로 구성된다. 이처럼 지표하에서는 크게 세 방향의 균열이 다른 방향을 보이는 균열에 비해 상대적으로 큰 빈도를 가지며 발달하고 있음을 알 수 있다. 대수층이 이방성이고 균질하다는 가정하에 양수시험을 실시하여 각각의 공에 대한 최대 투수량계수 ( $T_{{\varepsilon}{\varepsilon}}$)와 최소 투수량계수 ( $T_{ηη}$)값을 산출하고 주 텐서방향 ($\theta$)을 결정하였다. 그 결과 BH-1, BH-4, BH=5공을 제외한 BH-2, BH-3호공에서의 이방성 투수량계수텐서값은 이 논문의 가정인 대수층이 이방성이고 균질하다는 가정에 일치하지 않았다. 따라서 원형좌표계에 도시하였을 때 다른 공에 비해서 비균질성이 심한 결과로 인해 이방성타원체 에서 많이 벗어남을 보였다. 이로인해 3개의 공 BH-1, BH-4, BH-5호공을 사용하여 대수층의 이방성을 분석하여 보았다. BH-1호공에서의 $T_{{\varepsilon}{\varepsilon}}$는 171.90 $m^2$/day, $T_{ηη}$는 71.0l $m^2$/day이고 주 텐서방향은 Nl5.39$^{\circ}$ E로 나타났다. BH-4호공의 $T_{{\varepsilon}{\varepsilon}}$는 268.20 $m^2$/day, $T_{ηη}$는 28.75 $m^2$/day이고 주 텐서방향은 N7.55$^{\circ}$E이며 BH-5호공에서의 $T_{{\varepsilon}{\varepsilon}}$는 168.40 $m^2$/day, $T_{ηη}$는 66.80 $m^2$/day이고 주 텐서방향은 N76.59$^{\circ}$E로 나타났다. 이처럼 연구지역에서의 각각의 공에 대한 투수량계수텐서는 서로 다르게 나타났으며 이에 따른 주 텐서방향도 서로 다름을 알 수 있다.

• The Journal of the Korea Contents Association
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• v.7 no.2
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• pp.21-29
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• 2007

Anisotropic diffusion is one of the widely used techniques in the field of image segmentation. In the conventional anisotropic diffusion [1]-[6], usually 4-neighborhood directions are used: north, south, west and east, except the image diagonal directions, which results in the loss of image details and causes false contours. Existing methods for image segmentation using conventional anisotroplc diffusion can't preserve contour information, or noises with high gradients become more salient as the umber of times of the diffusion increases, resulting in over-segmentation when applied to watershed. In this paper, to overcome the shortcoming of the conventional anisotropic diffusion method, a new arusotropic diffusion method based on diagonal edges is proposed. And a method of watershed segmentation is applied to the proposed method. Experimental results show that the process time of the proposed method including diagonal edges over conventional methods can be up to 2 times faster and the Circle image quality improvement can be better up to $0.45{\sim}2.33(dB)$. Experiments also show that images are segmented very effectively without over segmentation.

• The Journal of Engineering Geology
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• v.11 no.2
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• pp.191-203
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• 2001

We investigate mechanical anisotropy dependent of rock fabric and its relationship with microcracks in the Pocheon Granite. Uniaxial compressive strengths range from 177MPa to 212MPa and the elastic constants are 48GPa-62GPa. The tensile strengths are 6.9MPa~8.5MPa and ultrasonic wave velocities range between 3,200m/sec and 3,700m/sec, indicating that mechanical anisotropy is strongly dependent of rock fabric. The minimum anisotropy ratio is 14% and the maximum is 24%, depend on the mechanical properties. The preferred orientations of microcracks are closely related with the directions of rock fabric. The preferred orientations of microcracks in feldspar are governed by the direction of mineralogical axis and are different from the directions of rock fabric. However, microcracks in quartz grains are very long and parallel to the directions of rock fabric, indicating that directions of rock fabric may be governed by the preferred orientations of microcracks in quartz grains. The preferred orientations of microcracks measured by differential strain analysis and microscopic observation are slightly different. That may be caused by different methodology. Lengths and numbers of microcrack are measured by microscopic observation. However, differential strain analysis measures the widths of microcracks.

• Journal of the Korean earth science society
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• v.28 no.2
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• pp.227-239
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• 2007

The MT data at the Okchon Belt show peculiar phase responses exceeding $90^{\circ}$. A reasonable explanation is that those responses are due to an electrical anisotropy structure which is composed of a narrow anisotropic block and an anisotropic layer. Considering the dominant anisotropic strikes of the block (NE-trend) and the layer (NW-trend) inferred from the MT data, if existing, the electrical anisotropy in the Okchon Belt was probably produced by the deformations in the pre-Jurassic period, since the NE-trending shearing or thrusting should create alternating bands of metamorphic rocks and fractures with NE-trending. Correlation of the structural strike of 2-D block with the latest EW-trending deformation events demonstrates that the geometrical structure of the anisotropic block was formed by the latest Daebo and Bulgugsa orogeny.

• Journal of the Korean Magnetics Society
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• v.4 no.3
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• pp.219-225
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• 1994

The alignment of Sr-ferrite magnetic powders, which is usually related to the fluidity and the applied magnetic field, is investicated in the anisotropic Sr-ferrite / resin-bonded permanent magnets. The magnetic powder alignment is observed to increase with the applied magnetic field and the fluidity which is a function of molding temperature and powder packing ratio. The best magnetic powder alignment is achieved at the following conditions; Sr-ferrite packing ratio of 56vol%, apparent viscosity of about 3000 poise in $1000sec^{-1}$ shear rate, and applied magnetic field of about 5kOe. The degree of preferred orientation of the magnetic powders in the field direction, as determined by the dc hysterisis graphs, is 84~85% (0.84~0.85). This result is in agreement with the value of 0.85 obtained by the X-ray experiments in the $2{\theta}$ range of ${23~40}^0$. The best magnetic properties obtained are:2.2kG of remanent flux density, 2.2MGOe of maximum energy product.

• Journal of the Korean Magnetics Society
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• v.23 no.2
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• pp.37-42
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• 2013

The out-of-plane and in-plane angular dependence of ferromagnetic resonance field was measured in NiFe thin films fabricated by magnetron sputtering. The effective magnetization was obtained from the out-of-plane angular dependence of ferromagnetic resonance field, which was well agreed with calculated one. The decrease of effective magnetization with NiFe thickness was due to the surface anisotropy constant of $K_s=-0.23\;erg/cm^2$. The in-plane uniaxial anisotropy fields were obtained from the in-plane angular dependence of ferromagnetic resonance field. The easy axis of in-plane uniaxial anisotropy field was rotated to the reverse direction of applied magnetic field during sample fabrication, which was explained by the antiferromagnetic NiFeO layer at sample surface.