• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.143-148
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• 2003

In recent years, as the optical Communication systems are developed, the demands of essential parts such as splitter, coupler, WDM, and AWG filter are grow rapidly. The fabrication process for them is not, however, automatic. On that reason, the automation is needed for the grow of productivity. The optical alignment and attach ment is the core process in fabrication. In this paper, the 6-axis rotary stage for multi-channel optical alignment system is developed and the dynamic characteristic of this system is studied.

• Interaction and multiscale mechanics
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• 제2권3호
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• pp.235-261
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• 2009

This study illustrates the differences between the elasto-plastic cap model and Lade's model with Cosserat rotation through the analyses of two large-scale geosynthetic-reinforced soil (GRS) retaining wall tests that were brought to failure using a monotonically increasing surcharge pressure. The finite element analyses with Lade's model were able to reasonably simulate the large-scale plane strain laboratory tests. On average, the finite element analyses gave reasonably good agreement with the experimental results in terms of global performances and shear band occurrences. In contrast, the cap model was not able to simulate the development of shear banding in the tests. In both test simulations the cap model predicted failure loads that were substantially less than the measured ones.

• Ocean Systems Engineering
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• 제1권3호
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• pp.195-205
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• 2011

A method for calibrating a laser profiling system for seafloor micro-topography measurements is described. The system consists of a digital camera and an arrangement of six red lasers that are mounted as a unit on a remotely operated vehicle (ROV). The lasers project as parallel planes onto the seafloor, creating profiles of the local topography that are interpreted from the digital camera image. The goal of the calibration was to determine the plane equations for the six lasers relative to the camera. This was accomplished in two stages. First, distortions in the digital image were corrected using an interpolation method based on a virtual pinhole camera model. Then, the laser planes were determined according to their intersections with a calibration target. The position and orientation of the target were obtained by a registration process. The selection of the target shape and size was found to be critical to a successful calibration at sea, due to the limitations in the manoeuvrability of the ROV.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 한국방송공학회 2009년도 IWAIT
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• pp.429-434
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• 2009

We introduce an instant and intuitive shadowing technique for CACAni System. In traditional 2D Anime, since all frames are drawn by hand it takes long time to create an entire animation sequence. CACAni System reduces such a production cost by automatic inbetweening and coloring. In this paper, we develop a shadowing technique that enables CACAni users to easily create shadow for character or object in the image. The only inputs required are sequences of character or object layers drawn in CACAni System with alpha value. Shadows are automatically rendered on a virtual plane based on these inputs. They can then be edited by CACAni users. Achieving this, CACAni System is able to handle instant shadowing and intuitive editing in a short time.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제24권7호
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• pp.1721-1730
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• 2000

An eccentric degenerated shell element with geometric non-linearity for the precise and efficient analysis of stiffened shell structures is developed. To deal with the eccentricity, we define the e ccentric shell and the master shell that constitute one combined shell. It is assumed that the sections remain plane after deformation. The internal force vector and the tangent stiffness matrix based on the virtual work principle in the natural coordinate system are derived. To enhance the robustness of the element, assumed strain method for transverse shear and membrane strains is used. Through numerical experiments the effectiveness of the proposed element is demonstrated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.141-145
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• 2014

A minimally appropriate time delay of audio data processing is investigated for rendering virtual sound source direction in real-time head-tracking environment under headphone listening. Less than 3.7 degree of angular mismatch should be maintained in order to keep desired sound source directions in virtually fixed while listeners are rotating their head in a horizontal plane. The angular mismatch is proportional to speed of head rotation and data processing delay. For 20 degree/s head rotation, which is a relatively slow head-movement case, less than total of 63ms data processing delay should be considered.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.150-155
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• 2005

In recent years, as the demands of VBNS(Very high speed Backbone Network Service) and VDSL(Very high-data rate Digital Subscriber Line) increase, the development of kernel parts of optical communication such as PLC(Planar Light Circuit), Coupler, WDM elements increase. The alignment and the attachment technology are very important to fabricate the optical elements for communication. In this paper, the mechanism of rotational stage are studied. with the three different method and the results of them are applied to the design of the system. The performance test of resolution and travel is performed.

• Structural Engineering and Mechanics
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• 제51권4호
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• pp.601-625
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• 2014

Based on continuum mechanics and the principle of virtual displacements, incremental total Lagrangian formulation (T.L.) and incremental updated Lagrangian formulation (U.L.) were presented. Both T.L. and U.L. considered the large displacement stiffness matrix, which was modified to be symmetrical matrix. According to the incremental updated Lagrangian formulation, small strain, large displacement, finite rotation of three dimensional Timoshenko fiber beam element tangent stiffness matrix was developed. Considering large displacement and finite rotation, a new type of tangent stiffness matrix of the beam element was developed. According to the basic assumption of plane section, the displacement field of an arbitrary fiber was presented in terms of nodal displacement of centroid of cross-area. In addition, shear deformation effect was taken account. Furthermore, a nonlinear finite element method program has been developed and several examples were tested to demonstrate the accuracy and generality of the three dimensional beam element.

• Structural Engineering and Mechanics
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• 제25권6호
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• pp.733-751
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• 2007

The metis element method (Hung 1978) has been applied to analyse free edge interlaminar stresses and delamination in composite laminates, which are subjected to extension and bending. The paper recalls Lekhnitskii's solution for generalized plane strain state of composite laminate and Wang's singular solution for determination of stress singularity order and of eigen coefficients $C_m$ for delamination problem. Then the formulae of metis displacement finite element in two-dimensional problem are established. Computation of the stress intensity factors and the energy release rates are presented in details. The energy release rate, G, is computed by Irwin's virtual crack technique using metis elements. Finally, results of interlaminar stresses, the three stress intensity factors and the energy release rates for delamination crack in composite laminates under extension and bending are illustrated and compared with the literature to demonstrate the efficiency of the present method.

• Current Optics and Photonics
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• 제4권6호
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• pp.540-544
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• 2020

Current two-dimensional (2D) augmented reality (AR) devices present virtual image and information to a fixed focal plane, regardless of the various locations of ambient objects of interest around the observer. This limitation can lead to a visual discomfort caused by misalignments between the view of the ambient object of interest and the visual representation on the AR device due to a failing of the singular fusion. Since the misalignment becomes more severe as the depth difference gets greater, it can hamper visual understanding of the scene, interfering with task performance of the viewer. Thus, we analyzed the range of singular fusion (RSF) of AR images within which viewers can perceive the shape of an object presented on two different depth planes without difficulty due to the failure of singular fusion. It is expected that our analysis can inspire the development of advanced AR systems with low visual discomfort.