• Journal of the Optical Society of Korea
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• 제17권1호
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• pp.33-37
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• 2013

In this study a new design concept of the Fabry-Perot filter, constructed with an anisotropic space layer and a couple of isotropic mirrors, was proposed based on the Maxwell equations and the characteristic matrix method. The single- and double-cavity Fabry-Perot filters were designed, and their optical properties were investigated with a developed software package. In addition, the dependence of the transmittance and phase shift for two orthogonal polarization states on the column angle of the anisotropic space layer and the incidence angle were discussed. We demonstrated that the polarization state of electromagnetic waves and phase shifts can be modulated by exploiting an anisotropic space layer in a polarization F-P filter. Birefringence of the anisotropic space layer provided a sophisticated phase modulation with varied incidence angles over a broad range, resulting in a wide-angle phase shift. This new concept would be useful for designing optical components with isotropic and anisotropic materials.

• Nuclear Engineering and Technology
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• 제53권10호
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• pp.3379-3397
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• 2021

In this study, a multi-physics modeling method was developed to analyze a nuclear fuel rod's thermo-mechanical behavior especially for high temperature anisotropic creep deformation during ballooning and burst occurring in Loss of Coolant Accident (LOCA). Based on transient heat transfer and nonlinear mechanical analysis, the present work newly incorporated the nuclear fuel rod's special characteristics which include gap heat transfer, temperature and burnup dependent material properties, and especially for high temperature creep with material anisotropy. The proposed method was tested through various benchmark analyses and showed good agreements with analytical solutions. From the validation study with a cladding burst experiment which postulates the LOCA scenario, it was shown that the present development could predict the ballooning and burst behaviors accurately and showed the capability to predict anisotropic creep behavior during the LOCA. Moreover, in order to verify the anisotropic creep methodology proposed in this study, the comparison between modeling and experiment was made with isotropic material assumption. It was found that the present methodology with anisotropic creep could predict ballooning and burst more accurately and showed more realistic behavior of the cladding.

• Structural Engineering and Mechanics
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• 제70권1호
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• pp.55-66
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• 2019

This work deals with the size-dependent wave propagation analysis of functionally graded (FG) anisotropic nanoplates based on a nonlocal strain gradient refined plate model. The present model incorporates two scale coefficients to examine wave dispersion relations more accurately. Material properties of FG anisotropic nanoplates are exponentially varying in the z-direction. In order to solve the governing equations for bulk waves, an analytical method is performed and wave frequencies and phase velocities are obtained as a function of wave number. The influences of several important parameters such as material graduation exponent, geometry, Winkler-Pasternak foundation parameters and wave number on the wave propagation of FG anisotropic nanoplates resting on the elastic foundation are investigated and discussed in detail. It is concluded that these parameters play significant roles on the wave propagation behavior of the nanoplates. From the best knowledge of authors, it is the first time that FG nanoplate made of anisotropic materials is investigated, so, presented numerical results can serve as benchmarks for future analysis of such structures.

• Geomechanics and Engineering
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• 제28권5호
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• pp.493-503
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• 2022

Cavity expansion is a classical problem in the field of solid mechanics with a wide range of applications in geotechnical and petroleum engineering. A drained solution is developed for cylindrical cavity expansion in anisotropic soils under biaxial in-situ stresses using a K0-based anisotropic modified Cam-clay model (K0-AMCC). The problem is formulated by solving differential equations using an auxiliary variable, which provides analytical expressions for the volume and four stress components of the soil around the cylindrical cavity. The solution is validated by comparisons with existing well-developed solutions. The results show that the present solution well captures the cavity expansion responses in anisotropic soils under biaxial in-situ stresses, and removes limiting assumptions that the cylindrical cavity expands under uniform in-situ stress in isotropic soils. The elastic-plastic boundary of the expanding cylindrical cavity in K0-consolidated anisotropic soils under biaxial in-situ stresses is a circle rather than an ellipse in isotropic soils, and the mathematical proof is provided in detail.

• 한국콘텐츠학회논문지
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• 제8권1호
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• pp.236-245
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• 2008

다양한 조명 환경 하에서, 얼굴인식이 잘 동작하도록 하는 것은 매우 어려운 일이며 성공적인 상업화를 위해서는 반드시 성취되어야 하는 작업이다. 본 논문에서는 얼굴 인식을 위한 효율적인 조명 전처리 방법을 제안한다. Anisotropic smoothing 기반 조명 전처리 방법은 조명 전처리 방법 가운데 효과적인 방법으로 잘 알려져 있으나, 원 이미지의 명도 대비를 감소시키며 에지 성분의 약화를 초래한다. 본 논문의 제안 방법은 기존 anisotropic smoothing 방법을 개선하여, 조명의 영향을 줄이면서 명도 대비를 증가시키고 에지 정보를 강화한다. 이러한 개선의 결과로, 본 논문의 제안 방법에 의해 조명 전처리된 같은 사람의 얼굴 이미지들은 보다 차별적인 특징 벡터(가버 특징 벡터)를 갖게 된다. 본 논문에서 제안한 조명 전처리 방법의 효율성은 가버젯 유사도를 이용한 얼굴 인식의 실험을 통하여 입증되었다.

• 소성∙가공
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• 제20권5호
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• pp.369-376
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• 2011

본 연구를 통하여 비이차 비등방 항복 응력 포텐셜들의 근접 짝되는 변형률 속도 포텐셜들에 대해서 정리하고 Yld2000-2d의 근접 짝되는 Srp2003-2d에 대해서 상세 설명하였다. 제안된 비이차 비등방 변형률 속도 포텐셜 Srp2003-2d 식 형태가 소개 되었고, 볼록성이 증명되었다. 아울러 이방성 상수를 구하는 방법이 제시되었다. Srp2003-2d의 소성 거동을 살펴보기 위하여 자동차 용 알루미늄 합금 판재 AA6022-T4와 항공재료용 알루미늄 합금 AA2090-T3에 응용되었다. Srp2003-2d는 항복 응력 포텐셜 Yld2000-2d와 거의 흡사한 짝됨을 보여 주었으며, 알루미늄 판재의 비등방성을 적절히 묘사하였다. Srp2003-2d는 알루미늄 판재의 성형 공정의 모사를 위하여 이상 공정 이론을 비롯한 강소성체 재료에 대한 정식화에 적절히 응용될 수 있을 것이다.

• Steel and Composite Structures
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• 제27권2호
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• pp.201-216
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• 2018

In this paper, three-dimensional (3D) elasticity theory in conjunction with nonlocal strain gradient theory (NSGT) is developed for mechanical analysis of anisotropic nanoparticles. The present model incorporates two scale coefficients to examine the mechanical characteristics much accurately. All the elastic constants are considered and assumed to be the functions of (r, ${\theta}$, ${\varphi}$), so all kind of anisotropic structures can be modeled. Moreover, all types of functionally graded spherical structures can be investigated. To justify our model, our results for the radial vibration of spherical nanoparticles are compared with experimental results available in the literature and great agreement is achieved. Next, several examples of the radial vibration and wave propagation in spherical nanoparticles including nonlocal strain gradient parameters are presented for more than 10 different anisotropic nanoparticles. From the best knowledge of authors, it is the first time that 3D elasticity theory and NSGT are used together with no approximation to derive the governing equations in the spherical coordinate. Moreover, up to now, the NSGT has not been used for spherical anisotropic nanoparticles. It is also the first time that all the 36 elastic constants as functions of (r, ${\theta}$, ${\varphi}$) are considered for anisotropic and functionally graded nanostructures including size effects. According to the lack of any common approximations in the displacement field or in elastic constant, present theory can be assumed as a benchmark for future works.

• 지구물리와물리탐사
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• 제10권4호
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• pp.393-398
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• 2007

흑색 셰일이 존재하는 지역에서 탄성파 주시 토모그래피 탐사를 수행하였다. 흑색 셰일은 퇴적암 기원으로 속도 이방성을 가지는 것으로 알려져 있기 때문에, 주시 토모그래피를 적용하여 정확한 역산 모형을 도출하기 위하여 이방성을 역산 과정에 적용하였다. 속도 이방성 계수는 탐사에서 획득한 자료에 대하여 탄성파의 초동시간에 의한 직선파선으로 가정한 속도와 전파각이 형성하는 이방성 타원의 형태로부터 추출할 수 있었으며, 이로부터 수평방향의 전파속도가 수직방향의 전파속도보다 빠름을 확인할 수 있었다. 속도 이방성 계수는 역산 과정에 적용되어 실제 지질구조에 부합하는 속도 구조를 획득하였다. 속도 이방성을 고려한 역산은 동일한 지역에서 3개의 구간에서 수행하였고, 각각의 결과는 지표지질 및 시추결과와 비교하여 높은 유사성을 보여주었다.

• 대한금속재료학회지
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• 제46권12호
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• pp.800-808
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• 2008

Heat treatment is an important step for tool manufacture, but unavoidably generates dimensional distortion. This study investigated the continuous dimensional change and the anisotropic behavior of STD11 tool steel during austenitizing and tempering heat treatment especially using quenching dilatometer. Dilatometric results represented that the dimensional change along longitudinal direction was larger than that along transverse direction. Anisotropic phase transformation strain was produced in forged STD11 tool steel during heat treatment. Anisotropic dimensional change increased with increasing austenitizing temperature. After tempering, anisotropic distortion was partially reduced. FactSage thermodynamic equilibrium phase simulation and microstructural observation (FE-SEM, TEM) showed that large ($7{\sim}80{\mu}m$) elongated $M_7C_3$ carbides could be formed along rolling direction. The resolution of elongated carbides during austenitizing was found to be related with the change of martensite transformation temperature after heat treatment. Anisotropic size change of STD11 tool steel was mainly attributed to large elongated carbides produced during rolling process. Using dilatometric and metallographic examination, the possible mechanism of the anisotropic size change was also discussed.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2004년도 High Temperature Superconductivity Vol.XIV
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• pp.3-3
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• 2004