• Broadcasting and Media Magazine
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• v.25 no.2
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• pp.17-26
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• 2020

최근 스마트폰에서의 증강현실, 미적 효과의 증대(예, 라이브 포커싱) 등의 어플리케이션을 제공하기 위해 모바일 기기에서의 3차원 공간 복원 기술에 대한 관심이 증가하고 있다. 소비자들의 요구에 발 맞춰 최근 스마트폰 제조사는 모든 플래그십 모델에 다중 카메라 및 뎁스 센서(거리 측정 센서)를 탑재하는 추세이다. 본 고에서는 모바일 폰에 탑재되고 있는 대표적인 세 축의 뎁스 추정(공간 복원) 방식에 대해 간단히 살펴보고, 최근 심층학습(Deep learning)의 등장으로 기술 발전의 새로운 국면에 접어 든 다중 시점 매칭(Multi-view stereo) 방법에 대해 소개하고자 한다. 심층 신경망이 재조명 받은 2012년 전까지 주류 연구 방향이었던 전통 기하학 기반의 방법에 대한 소개를 시작으로 심층 신경망기반의 방법론으로의 발전된 형태를 살펴본다. 또한, 신경망기반의 방법론은 크게 3 세대로 나누어 각 세대별 특징에 대해 자세히 살펴보고, 다양한 데이터에 대한 실험 결과를 통해 세대별 공간 복원 결과를 비교 분석한다.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.72-83
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• 2009

The purpose of this study is to examine the effects of a degree of discretization in the direction of longitudinal dam axis on the results of three dimensional fill dam dynamic analysis. In this study, the three dimensional dynamic analyses of the existing 'H' dam which is modeled with a different degree of discretization were carried out. From these results, the fundamental frequency of the dam and the responses at the dam crest such as acceleration and settlement were compared and analyzed. It was concluded that the size of finite element discretized in the direction of the longitudinal axis mush be smaller than 1/8 of dam length in order to obtain the reasonable fundamental frequency and response of acceleration and mush be smaller than 1/10 in order to obtain the reasonable settlement behaviors from the three dimensional dynamic analysis of the fill dam.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.85-87
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• 1998

In general, we apply the 2 dimensional method to analyze the characteristic of electric machinery. But it is very difficult to analyze the air-cored machine like as superconducting generator, because it have 3 dimensional flux distribution. In this paper, we compare the analysis r between 2D and 3D. 3D Finite Element Meth applied to the superconducting generator at n condition. And we studied the characteristic acc to the axial length of magnetic shield.

• Journal of the Korean Society for Precision Engineering
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• v.8 no.1
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• pp.116-129
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• 1991

A cutting force model for face milling operation using 3-directional specific cutting force coefficients is developed. The model is taken into consideration factors such as cutter geometry, machining conditions, spindle eccentricity, insert initial postion errors, etc. The simulated force in X, Y, Z directions from the model are subsequently compared with measured forces in the time and frequency domains. The simulated forces have a good agreement with measured forces.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.2
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• pp.24-29
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• 1998

An experimental study was carried out to investigate the characteristics of spray pattern such as discharge coefficient, spray angle, and mass distribution for two-fluid airblast swirl injector, within the range of fluid supply pressure 0~13kg/$\textrm{cm}^2$. In general atomization is promoted with increasing total gas mass flow and performance of the splay pattern was more stable when radial mass flow was greater than axial mass flow, radial swirler was better than Axial swirler for atomization. Equivalent spray angle did not change with water mass flow except for the condition of 3kg/$\textrm{cm}^2$ and showed the same for the gas mass flow. Mass distribution from the patternator shows that maximum value of the distribution were lowered but distributed larger area when gas flow rate increased. Center of mass position did not change with increasing water mass flow.

• Journal of the Korean Wood Science and Technology
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• v.19 no.3
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• pp.7-18
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• 1991

목재(木材)의 액체침투성(液體浸透性)을 연구(硏究)하기 위하여 국내(國內)에 있는 침엽수재(針葉樹材)와 활엽수재(闊葉樹材)의 주요수종(主要樹種)을 대상으로 축방향(軸方向), 방사방향(放射方向), 접선방향(接線方向)의 침투(浸透)를 각각 조사(調査)하였다. 또한 방사(放射) 및 접선방향(接線方向)의 주요(主要) 침투경로(浸透經路)를 광학현미경(光學顯微鏡)으로 관찰(觀察)하였다. 실험결과(實驗結果)는 다음과 같다. 1. 종침투(縱浸透)는 침(針) 활엽수재(闊葉樹材)모두 1% $NH_4OH$ 처리(處理)시 침투성(浸透性)이 가장 컸으며 수종(樹種)에 따른 침투성(浸透性)의 차이(差異)는 침엽수재(針葉樹材)인 잣나무가 활엽수재(闊葉樹材)인 물푸레나무와 현사시나무 보다는 더 컸으며 관엽수재내(關葉樹材內)에서는 물푸레나무가 현사시나무보다 침투성(浸透性)이 더 큰 것으로 나타났다. 2. 횡침투(橫浸透)는 침엽수재(針葉樹材)에 있어서 침투면별(浸透面別) 침투량(浸透量)은 접선단면(接線斷面)이 방사단면(放射斷面)보다 훨씬 컸으며, 활엽수재(闊葉樹材)의 경우는 환공재(環孔材)에서는 접선단면(接線斷面)이 방사단면(放射斷面)보다 침투량(浸透量)이 컸으나, 산공재(散孔材)에서는 수종간(樹種間)의 변이(變異)가 컸다. 활엽수재(闊葉樹材)의 환공재(環孔材) 모두 방사조직(放射組織)이 횡침투(橫浸透)에 미치는 영향(影響)은 침엽수재(針葉樹材)만큼 크지 않았다. 침투(浸透)깊이도 침엽수재(針葉樹材)가 활엽수재(闊葉樹材)보다 컸으며, 활엽수재(闊葉樹材)는 수종간(樹種間)의 차이(差異)가 심했다. 3. 침투경로(浸透經路)를 보면 침엽수재(針葉樹材)는 방사유세포(放射柔細胞), 만재부(晩材部)의 소가도관(小假導管)이 주도적(主導的)인 역할을 하였으며, 활엽수재(闊葉葉材)도 역시 방사조직(放射組織)을 통해서 침투(浸透)가 이루어지지만 수종간(樹種間)에 방사조직(放射組織)의 침투양식(浸透樣式)과 침투속도(浸透速度)가 달랐다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.59-59
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• 2010

ZnO는 II-VI 족 화합물 반도체로써 상온에서 큰 엑시톤 결합에너지 (~60 meV) 를 가지며 밴드갭이 3.37 eV인 직접 천이형 반도체로 잘 알려진 물질이다. 이러한 ZnO의 물리적 특성은 광학소자로 상용화된 GaN와 유사하기 때문에 LED나 LD등의 광 소자 재료로 주목 받고 있다. 또한 ZnO는 3족 원소 (In, Ga, Al)를 도핑 함으로써 전기적 특성 제어가 가능한 장점을 가지고 있다. 본 연구는 펄스레이저 증착법 (Pulsed Laser Deposition)을 이용하여 Si (111) 기판 위에 ZnO:In 박막을 성장 시켰으며, 도핑된 indium 양에 따른 ZnO 박막의 배향성 변화를 관찰 하였다. X-선 회절 분석법 (X-ray diffraction), 탐침형 원자현미경 (Atomic Force Microscope) 그리고 투과전자 현미경 (Transmission Electron Microscope)을 측정하였다. XRD 측정 결과 un-doped ZnO 박막은 (002) 방향으로 c-축 우선성장 하였다. 그러나 ZnO 박막내의 Indium 양이 증가 할수록 (002) 방향에서 (101), (102), (103) 등의 (101) 방향으로 성장이 변화 하였으며 5 at.% 이상에서는 (100) 방향의 성장이 관찰 되었다. TEM 측정 결과 un-doped ZnO 박막은 columnar 구조로 성장 되었으나, Indium 양이 증가할수록 column의 size가 감소하며, 5 at.% 이상에서 columnar 구조 성장이 거의 관찰되지 않는다. AFM 결과에서는 Indium 양이 증가 할수록 박막의 표면거칠기와 결정립 크기가 감소하였다.

• Journal of the Korean Magnetics Society
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• v.26 no.2
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• pp.45-49
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• 2016

Ground state energy levels of $Gd^{3+}$ ion (effective spin S = 7/2) in $PbWO_4$ single crystal doped with $Gd^{3+}$ paramagnetic impurity at tetragonal symmetry are calculated with spectroscopic splitting parameters and zero field splitting parameters using by effective spin Hamiltonian. It turns out that the zero field splitting energies of $Gd^{3+}$ ion were the same regardless of the directions of $PbWO_4$ : Gd single crystal. The calculated energy differences for ${\mid{\pm}7/2}$ > ${\leftrightarrow}{\mid{\pm}5/2}$ >, ${\mid{\pm}5/2}$ > ${\leftrightarrow}{\mid{\pm}3/2}$ >, and ${\mid{\pm}3/2}$ > ${\leftrightarrow}{\mid{\pm}1/2}$ > transitions were 6.9574 GHz, 6.9219 GHz, and 15.8704 GHz, respectively when the applied magnetic field is zero. The calculated energy level diagrams were different for different directions of applied magnetic field. For B // a- and c-axis, the energy level diagrams are calculated and discussed.

• Journal of the Korean Geophysical Society
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• v.3 no.2
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• pp.99-112
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• 2000

The Iksan Jurassic Granite shows relatively less fractures and homogeneous rock fabrics, and is one of the most popular stone materials for architectures and sculptures. Almost mutually perpendicular rift, grain, and halfway in the Iksan Jurassic Granite are well known to quarrymen based on its splitting directions, and therefore it should exhibit orthorhombic symmetry. Theoretically, there are 9 independent elastic stiffness coefficients $(C_{1111},\;C_{2222},\;C_{3333},\;C_{2323},\;C_{1313},\;C_{1212},\;C_{1122},\;C_{2233},\;and\;C_{1133})$ for orthorhombic anisotropy. In order to characterize the static and dynamic elastic properties of the Iksan Jurassic Granite, triaxial strains under uniaxial compressive stresses and ultrasonic velocities of elastic waves in three different polarizations are measured. Both experiments are carried out with six directional core samples from massive rock body. Using the results of experiments and the densities measured independently, the static and dynamic elastic coefficients are computed by simple mathematical manipulation derived from the governing equations for general anisotropic media. The static elastic coefficients increase ar uniaxial compressive stress rises. Among those, the static elastic coefficients at uniaxial compressive stress of a 24.5 MPa appear to be similar to the dynamic elastic coefficients under ambient condition. Although some deviations are observed, the preferred orientations of microcracks appear to be parallel or subparallel to the rift, the grain, and the hardway from microscopic observation of thin sections. This indicates that the preferred orientations of microcracks cause the elastic anisotropy of the Iksan Jurassic Granite. The results are to be applied to the effective use of the Iksan Jurassic Granite as stone materials, and can be used for the non-destructive safety test.

• The Journal of Engineering Geology
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• v.8 no.1
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• pp.75-86
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• 1998

Eighteen oriented samples from the Jeongsun limestone of the Joseon Supergroup are collected. The orientations of C-axis of calcite and e twin plane, the average thickness, numbers of twins and the widths of calcite grains in 10 samples are measured. Then, the twin strain, mean width, intensity of twin and relative magnitude and orientations of principal stresses are calculated using Calcite Strain Gauge program. Twin strain, mean width and intensitv rainge between 0.801%~10.927%, $0.43{\mu\textrm{m}}~2.03{\mu\textrm{m}}$, and 33.5~113.4twim/mm, respectively. Metamorphic temperatures calculated from twin show below $70^{\circ}C$, indicating that twins were developed within 2.3km depth. In five samples, two events with different orientations of principal stress produced calcite twins, while only one event produced calcite twins in five samples. The direction of the maximum stress is almost horizontal and the minimum is almost vertical, indicating that the stress regirne is identical with thrust fault. E-W and NW-SE are the most dominant directions of comressive stress and N-S and NE-SW directions are also shown. Comparision between paleostress orientations measured in the study and others indicates that the maximum horizontal stress oriented to E-W may represent the paleostress of period either from the Silurian to the Triassic or from the Silulian to the Permian. Paleostress oriented to NW-SE may be the major direction of stress during the Daeho orogeny.