• 한국재료학회지
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• 제18권7호
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• pp.362-366
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• 2008

The precipitation behavior in Mg-6 wt%Zn-1 wt%Y alloy annealed at different temperatures of $200^{\circ}C$ and $400^{\circ}C$ has been characterized by high resolution transmission electron microscope. When the alloy is annealed at $200^{\circ}C$ for 6 hr, the plate- and the rod-shaped ${\beta}_2'$ phases are precipitated in the matrix. The orientation relationship of plate-shaped precipitates with the matrix exhibits a [$11{\bar{2}}0]{\beta}_2$ || [$10{\bar{1}}0$]Mg, $(0001){\beta}_2'$ || (0001)Mg. While the rod-shaped precipitates have two kinds of the orientation relationships with the matrix, i.e. $[11{\bar{2}}0]{\beta}_2'$||[0001] Mg, $(0001){\beta}_2'||(11{\bar{2}}0)$ Mg and $[11{\bar{2}}0]{\beta}_2'$||[0001] Mg, $({\bar{1}}106){\beta}_2'||(10{\bar{1}}0)$ Mg. With increasing annealing time at $200^{\circ}C$ the ${\beta}_1'$ phases are also precipitated in the matrix and the orientation relationship exhibits a $[010]{\beta}_1'$ || [0001]Mg, $(603){\beta}_1'$ || ($01{\bar{1}}0$)Mg between the ${\beta}_1'$ precipitate and the matrix. The icosahedral phases are precipitated in the alloy annealed at $400^{\circ}C$ and exhibit a $[I2]_I$ || [0001]Mg relationship with the matrix.

• 건축역사연구
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• 제16권6호
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• pp.47-66
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• 2007

$Lokap{\bar{a}}las$ are understood as the deities of four directions in Buddhism: $Dhrtar{\bar{a}}stra$ in the East, $Vir{\bar{u}}dhaka$ in the South, $Vir{\bar{u}}p{\bar{a}}ksa$ in the West and $Vai{\acute{s}}ravana$ in the North respectively. Their common name is, therefore, called as the "Four Guardian Kings", whose function is to prevent demonic forces from entering into its sacred world. Although the position of $Lokap{\bar{a}}las$ is to the lowest level in the hierarchy of the minor deities in Buddhism, the cult of $Lokap{\bar{a}}las$ was widely spread and prominent in the countries of Northern Buddhism. It played a significant role in terms of the state-protecting Buddhism, on behalf of it's esoteric and magic power. More than 20 Gateways of the $Lokap{\bar{a}}las$ and $Lokap{\bar{a}}la$ statues were still well preserved in Korea, and they were believed to be constructed after the Japanese attack in 1592. After war, monks had concentrated on restoring ruined temples and building many new Gateways of the Four Guardian Kings over the Korean peninsular. Under such circumstances, even though the $Lokap{\bar{a}}las$ played a significant role as the subject of cult in Korean Buddhism. they might have a small chance to be taught traditional Lama iconography exactly. The purpose of this essay is to examine the relation of orientation of the Gate way of $Lokap{\bar{a}}las$ and allocation of each Kings inside the gate.

• 열처리공학회지
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• 제22권3호
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• pp.155-161
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• 2009

An investigation of the deformation behavior of ${\gamma}'-Ni_3Al$ single crystals containing fine dispersion of disordered ${\gamma}$ particles was performed for several different crystal orientations. Deformation structures were observed by the weak-beam method of transmission electron microscopy (TEM). The critical resolved shear stress (CRSS) for (111) [$\bar{1}$01] slie. increases with increasing temperature in the temperature range where (111) slip operates. The CRSS for (111) [$\bar{1}$01] slip is dependent on crystal orientation in the corresponding temperature range. The temperature where the strenjlth reaches a maximum is dependent on crystal orientation; the higher the ratio of the Schmid factors of (010) [$\bar{1}$01] to that of (111) [$\bar{1}$01], the higher the peak temperature. The peak temperatures were increased by the precipitation of y particles for the samples of all orientations. Electron microscopy of deformation induced dislocation arrangements under peak temperature has revealed that most of dislocations are straight screw dislocations. The mobility of screw dislocations decreases with increasing temperature. Above the peak temperature, dislocations begin to cross slip from the (111) [$\bar{1}$01] slip system to the (010) [$\bar{1}$01] slip system, thus decreasing the strength.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.70-73
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• 2000

A finite element analysis model is suggested for analysis of forming process of milli structure whose size is from a few hundreds ${\mu}m$ to a few mm. In this paper, finite element formulation which assemble crystal plasticity theory considering texture development with damage mechanics is developed, since orientation development and growth of micro voids became the primary factors for deformation aspects in large deformation of milli structure. Applying to, extremely, extrusion process of single crystal and extrusion/drawing process of polycrystal milli-size bar, extrusion force, preferred orientation, and damage evolution are examined to understand the characteristics of deformation of milii-size bar.

• 산업기술연구
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• 제21권A호
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• pp.221-229
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• 2001

The effect of Mo underlayer on the magnetic properties of CoCrTa/Cr films deposited on glass substrates were investigated. The coercivity increased and the coercivity squareness decreased by introducing Mo underlayer. The coercivity increase was attributed to the increase of in-plane c-axis orientation and magnetic isolation of Co grains deposited on Cr/Mo underlayer. The decrease of coercivity squarenesses seemed to be caused by the increase of magnetic isolation. The increase of magnetic isolation of Co grains was attributed to the diffusion of Mo atoms into grain boundaries of Co films and the physical isolation of Co grains. The coercivity of CoCrTa/Cr/Mo showed maximum values at Mo thickness of $400{\AA}$. The appearance of the maximum coercivity at that thickness was attributed to the development of strong $Co(10{\bar{1}}0)$ and $Co(10{\bar{1}}1)$ preferred orientation.

• 한국정보통신학회논문지
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• 제11권11호
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• pp.2143-2149
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• 2007

최근 시각 장애인을 위한 인공망막 모델 구현에 관한 연구 중 시피질 자극기 기술은 시각 자극 전달의 중간 단계를 생략하고 직접 뇌세포를 자극하는 것이다. 본 논문에서는 망막에서 시각 피질로 시각정보를 전달할 때 발생하는 시각 피질의 특성, 즉 방향성에 대한 반응 특성을 특징 데이터로 구성하여 인식함으로써 인간 시각 정보 처리와 유사한 영상 추출 및 인식 모델을 제안한다. 제안된 방법은 영상의 특징을 추출 한 후 Delta-bar-delta 기반 오류 역전파 알고리즘을 적용하여 영상의 특징들을 인식한다. 제시된 방법의 성능을 분석하기 위하여 다양한 숫자 패턴들을 대상으로 실험한 결과, 제안된 망막 세포로부터 전달된 정보를 방향성에 대한 민감성을 고려하여 영상의 특성을 추출하여 인식하는 모델이 기존의 영상 추출 및 인식 모델보다 인식률에 있어서는 별 차이가 없지만 다양한 실험에서 확인할 수 있듯이 인간 시각과 같이 인식 성능이 민감하지 않는 것을 알 수 있었다.

• 한국공작기계학회논문집
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• 제10권1호
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• pp.112-119
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• 2001

Design sensitivity is an important is an important device in improving a mechanical system design. A continuum design consists of the shape and orientation design. This research develops the shape and orientation design sensitivity method. The configura-tion design variables of multibody systems define the shape and orientation changes. The equations of motion are directly differentiated to obtain the governing equations for the design sensitivity. The governing equation of the design sensitivity is formulated as an over determined differential algebraic equation and treated as ordinary differential equations on mani-folds. The material derivative of a domain functional is performed to obtain the sensitivity due to shape and orientation changes. The configuration design sensitivities of a fly-ball governor system and a spatial four bar mechanism are obtained using the proposed method and are validated against those obtained from the finite difference method.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 추계학술대회
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• pp.308-309
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• 2009

인간의 시각정보처리는 망막에서 입력된 영상을 시각피질에 전달될 때 많은 특성을 가지고 있다. 그중에서 방향성에 대한 민감한 반응을 분석하여 영상인식에 미치는 영향을 분석하고자 한다. 수직반응의 가중치와 수평 및 대각선반응의 가중치를 여러 가지로 변동하여 영상의 인식률을 비교함으로써 수직반응 정도에 매우 민감함을 보이며 차후 인간시각모델 구성에 적용하고자 한다.

• 대한기계학회논문집A
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• 제40권1호
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• pp.23-31
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• 2016

본 연구에서는 연성 금속재료의 판상형 인장 시편에 대한 동적 물성을 측정하기 위한 인장형 홉킨슨 바(TSHB, Tensile split Hopkinson bar)의 수정 방법에 대해 논의하고, 이를 이용하여 고순도 알루미늄 단결정 및 멀티결정재의 동적 물성을 측정하였다. 시편의 초기 미세조직 및 결정학적 방위는 전자후방 산란회절(EBSD, Electron backscattered diffraction) 분석을 통하여 측정하였으며, 동적 변형 후 파단 형상을 광학 현미경을 통하여 확인하였다. 고속인장 변형 중 시편 내부에 발생하는 변형 분포는 디지털 이미지 상관(DIC, Digital image correlation) 기법을 이용하여 측정하였다. 이를 통해 동적 변형 중 나타나는 알루미늄의 거시적인 소성 변형과 결정학적 방위 및 미세 조직과의 상관관계에 대해 논의하였다.

• Tribology and Lubricants
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• 제33권3호
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• pp.106-111
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• 2017

Sapphire is an anisotropic material with excellent physical and chemical properties and is used as a substrate material in various fields such as LED (light emitting diode), power semiconductor, superconductor, sensor, and optical devices. Sapphire is processed into the final substrate through multi-wire saw, double-side lapping, heat treatment, diamond mechanical polishing, and chemical mechanical polishing. Among these, chemical mechanical polishing is the key process that determines the final surface quality of the substrate. Recent studies have reported that the material removal characteristics during chemical mechanical polishing changes according to the crystal orientations, however, detailed analysis of this phenomenon has not reported. In this work, we carried out chemical mechanical polishing of C(0001), R($1{\bar{1}}02$), and A($11{\bar{2}}0$) substrates with different sapphire crystal planes, and analyzed the effect of crystal orientation on the material removal characteristics and their correlations. We measured the material removal rate and frictional force to determine the material removal phenomenon, and performed nano-indentation to evaluate the material characteristics before and after the reaction. Our findings show that the material removal rate and frictional force depend on the crystal orientation, and the chemical reaction between the sapphire substrate and the slurry accelerates the material removal rate during chemical mechanical polishing.