• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 추계 학술발표회 논문집
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• pp.11-18
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• 2002

The Ulsan fault with NNW-SSE strike is a very wide and long lineament about 50km along Gyeungju-Ulsan line in the southeastern part of Korea. According to previous studies the Ulsan fault was not considered as a fault but only long lineament since no displacement was found along the lineament. Recently several Quaternary faults were reported in the northeastern part of lineament, which implies the neotectonic movement in this area. We analysed drainage pattern and stream gradient using the DEM (Digital Elevation Model) data for both side of Ulsan fault line to check the recent topographic changes which indicate neotectonic movement. The result shows that stream index in the eastern part of Ulsan fault is higher than the one in the western part. This means that recent tectonic movement is more active in the eastern part of Ulsan fault.

• 한국광학회지
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• 제7권1호
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• pp.24-27
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• 1996

790nm의 반도체 레이저를 이용하여 수용액 속에 잠겨있는 $3~4\mu\textrm{m}$크기의 yeast입자를 포획하는데 성공하였다. 포획된 입자는 2차원 평면과 3차원 공간의 이동에도 안정된 포획 상태를 유지하였다. 이 실험으로 레이저 광속이 매질과 입자의 표면에서 굴절할 때, 입자의 굴절률과 매질의 굴절률의 차에 의하여 생기는 광압의 존재를 확인하였다. 그리고 레이저 광속에 수직하게 입자를 움직이면서 레이저 광속에 수직한 방향의 포획력을 측정하고 레이저의 출력에 따른 변화를 연구하였다.

• Journal of the Optical Society of Korea
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• 제14권4호
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• pp.424-430
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• 2010

In coherent anti-Stokes Raman scattering (CARS) microscopy reported until now, conventional microscope objectives are used, so that they are limited for introduction into a living body. Gradient-index (GRIN) rod lenses might be a solution for miniaturized microscope objectives for in-vivo CARS microscopy. However, due to the inherent large amount of chromatic aberration, GRIN rod lenses cannot be utilized for this purpose. CARS imaging catheter, composed of miniaturized microscope objective and fiber bundle, can be introduced into a living body for minimally invasive diagnosis. In order to design the catheter, we have to first investigate design requirements. And then, the optical design is processed with design strategies and intensive computing power to achieve the design requirements. We report the miniaturized objective lens system with diffraction-limited performance and completely corrected chromatic aberrations for an in-vivo CARS imaging catheter.

• Structural Engineering and Mechanics
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• 제60권4호
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• pp.707-727
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• 2016

In this paper, thermal vibration of a nonlocal functionally graded (FG) plates with arbitrary boundary conditions under linear and non-linear temperature fields is explored by developing a refined shear deformation plate theory with an inverse cotangential function in which shear deformation effect was involved without the need for shear correction factors. The material properties of FG nanoplate are considered to be temperature-dependent and graded in the thickness direction according to the Mori-Tanaka model. On the basis of non-classical higher order plate model and Eringen's nonlocal elasticity theory, the small size influence was captured. Numerical examples show the importance of non-uniform thermal loadings, boundary conditions, gradient index, nonlocal parameter and aspect and side-to-thickness ratio on vibrational responses of size-dependent FG nanoplates.

• Steel and Composite Structures
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• 제26권5호
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• pp.607-620
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• 2018

Vibration analysis of deep curved FG nano-beam has been carried out based on modified couple stress theory. Material properties of curved Timoshenko beam are assumed to be functionally graded in radial direction. Governing equations of motion and related boundary conditions have been obtained via Hamilton's principle. In a parametric study, influence of length scale parameter, aspect ratio, gradient index, opening angle, mode number and interactive influences of these parameters on natural frequency of the beam, have been investigated. It was found that, considering geometrical deepness term leads to an increase in sensitivity of natural frequency about variation of aforementioned parameters.

• Journal of Astronomy and Space Sciences
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• 제30권1호
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• pp.11-15
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• 2013

A collision-free formation reconfiguration trajectory subject to the linearized Hill's dynamics of relative motion is analytically developed by extending an algorithm for gravity-free space. Based on the initial solution without collision avoidance constraints, the final solution to minimize the designated performance index and avoid collision is found, based on a gradient method. Simple simulations confirm that satellites reconfigure their positions along the safe trajectories, while trying to spend minimum energies. The algorithm is applicable to wide range of formation flying under the Hill's dynamics.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2009년도 Korea Superconductivity Society Meeting 2009
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• pp.72-72
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• 2009

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.439-443
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• 1996

A fuzzy teaming controller is experimentally designed to control the ball k beam system in this paper. Although most fuzzy controllers have been built just to emulate human decision-making behavior, it is necessary to construct the rule bases by using a learning method with self-improvement when it is difficult or impossible to get them only by expert's experience. The algorithm introduces a reference model to generate a desired output and minimizes a performance index function based on the error and error-rate using the gradient-decent method. In our balancing experiment of the ball ＆ beam system, this paper shows that the fuzzy control rules by learning are superior to the expert's experience.

• 한국광학회지
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• 제9권5호
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• pp.300-306
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• 1998

광학용 유전체 다층박막의 증착시 높은 열로 인해 형성되는 층간확산의 광학적 효과를 연구하였다. 연속적으로 변하는 굴절률 분포함수를 갖고 하나의 부분구조가 주기적으로 반복되는, 다층박막의 광특성 계산방법을 제시한다. 이 방법을 이용하여 Fabry-Perot형 여과막, 넓은 영역에 걸쳐 높은 반사율을 갖는 전반사경 및 반사 방지막에 대해 층간확산이 미치는 영향을 계산하여 투과 및 반사 스펙트럼을 얻었다. 층간확산으로 인하여 전반사경의스펙트럼 대역폭이 줄어들었으며 다층 반사방지막의 경우층의 수가 많을 때 특성이 악화되고 파장에 따른 반사율의 변화가 크게 되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.132-136
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• 2002

Optical collimating lenses are play a role as maintenance parallel light and as a kind of optical collimating lens, there is Ball lenses, GRIN-rod lenses, spherical lenses and aspherical lenses etc. but recently GRIN lens has monopolized a market. The performance of optical collimator depended on the coupling efficiency. In this paper, we were compared and analyzed to be measured values of coupling efficiency with respect to optical working distance using GRIN rod lenses and spherical lenses. In the case of GRIN lenses with a beam size of 420 ${\mu}{\textrm}{m}$, the minimum coupling efficiency was obtained to a measured value of 0.15 ㏈ and in the case of spherical lenses was obtained to a measured value of 0.12 ㏈ on the same condition. In results, we found that a performance of spherical lenses be better as compared with a that of GRIN lens.