• Geotechnical Engineering
• /
• v.6 no.3
• /
• pp.65-76
• /
• 1990

A series of consolidated drained and untrained cubical triaxial tests were performed to investigate three dimensional strength characteristics of compressible sand. All specimens, which are formed by deposisting a fine sand loosely, were used. Failure strength in terms of effective stress analysis was greatly influenced by the variation of intermediate principal stress and so was failure criterion The adjusted effective frictional angles obtained by the stress state projected on the same octahedral plane showed almost same value, while the measured effective frictional angles showed considerable difference depending on the drainage conditions. Results of total stress analysis in undrained test turned out to fit Tresca's failure criterion well, but results of effective stress analysis turned out to fit Lade's failure criterion well.

• Korean Journal of Optics and Photonics
• /
• v.9 no.6
• /
• pp.368-372
• /
• 1998

A 16-views 3 dimensional imaging system is designed by spatially combinding two 8-views time multiplexed image channels. Each 8-views channel composed of 3 primary color CRTs and a dichroic beam splitter which combining the three CRTs as one channel. Each CRT displays 8-view images time sequentially. These images are projected to a holographic screen of a size 1$\times$0.8 $m^2$ through a projection optics. Characteristics of the three different configurations of projection optics are examined with the optics designing program "DEMOS" to select an optimized projection optics for the system. The configulation of the optimized projection optics is found like following; images from each channel combined by two-fold mirror are projected by a projection objective through a 16-strips LCD shutter. In this configuration, the shutter should be located at the entrance pupil of the objective, and the folded edge of the two-fold mirror should contact symmetrically to the center line of the shutter.e shutter.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.11 no.9
• /
• pp.782-787
• /
• 2001

In this paper, we propose an growing and pruning algorithm to design the adaptive structure of modular wavelet neural network(MWNN) with F-projection and geometric growing criterion. Geometric growing criterion consists of estimated error criterion considering local error and angel criterion which attempts to assign wavelet function that is nearly orthogonal to all other existing wavelet functions. There criteria provide a methodology that a network designer can constructs wavelet neural network according to one s intention. The proposed growing algorithm grows the module and the size of modules. Also, the pruning algorithm eliminates unnecessary node of module or module from constructed MWNN to overcome the problem due to localized characteristics of wavelet neural network which is used to modules of MWNN. We apply the proposed constructing algorithm of the adaptive structure of MWNN to approximation problems of 1-D function and 2-D function, and evaluate the effectiveness of the proposed algorithm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.10a
• /
• pp.190-192
• /
• 2018

This paper describes a design of an elliptic curve cryptography (ECC) processor that supports five pseudo-random curves and five Koblitz curves over binary field defined by the NIST standard. The ECC processor adopts the Lopez-Dahab projective coordinate system so that scalar multiplication is computed with modular multiplier and XORs. A word-based Montgomery multiplier of $32-b{\times}32-b$ was designed to implement ECCs of various key lengths using fixed-size hardware. The hardware operation of the ECC processor was verified by FPGA implementation. The ECC processor synthesized using a 0.18-um CMOS cell library occupies 10,674 gate equivalents (GEs) and 9 Kbits RAM at 100 MHz, and the estimated maximum clock frequency is 154 MHz.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39B no.9
• /
• pp.590-597
• /
• 2014

This paper proposes multi-camera system that relies on 3D views for panoramic video and distribution method about panoramic video generation algorithm by using cloud computing. The proposed monitoring system monitors the projected 3D model view, instead of individual 2D views, to detect image distortions. This can minimize compensation errors caused by parallax, thereby improving the quality of the resulting panoramic video. Panoramic video generation algorithm can be divided into registration part and compositing part. Therefore we propose off-loading method of these parts with cloud computing for panoramic video service.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.10
• /
• pp.2443-2450
• /
• 2014

In the motion recognition system using depth image, the depth image is converted to the real world formed 3D point cloud data for efficient algorithm apply. And then, output depth image is converted by the projective world after algorithm apply. However, when coordinate conversion, rounding error and data loss by applied algorithm are occurred. In this paper, when convert 3D point cloud data to depth image, we proposed efficient conversion method and its hardware implementation without rounding error and data loss according image size change. The proposed system make progress using the OpenCV and the window program, and we test a system using the Kinect in real time. In addition, designed using Verilog-HDL and verified through the Zynq-7000 FPGA Board of Xilinx.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.10a
• /
• pp.293-296
• /
• 2016

In case of an emergency on a busy road of a city, drivers should make way for special vehicles such as police cars, fire engines, or ambulance as soon as possible. If road infrastructures recognize the movements of special vehicles, and transfer alert message to traffic signal controllers and normal cars through wireless network such as WAVE or TPEG, normal cars can prepare to make way in advance. As a result, it help special vehicles move faster. In this paper, we install a roof mark on the roof of a special vehicle, detect the mark through a mark recognition algorithm which includes perspective transformation, and get the inner information by decoding the digital pattern on it. The experiment results show that mark can be recognized 100% and 93.3% of inner digital data of the mark can be recognized, when the size of a mark is larger than $88cm{\times}88cm$ and the mark moves at a speed of 50km/s.

• KIPS Transactions on Software and Data Engineering
• /
• v.8 no.2
• /
• pp.89-96
• /
• 2019

360 degree 3-dimensional lidar sensors and vision cameras are commonly used in the development of autonomous driving techniques for automobile, drone, etc. By the way, existing calibration techniques for obtaining th e external transformation of the lidar and the camera sensors have disadvantages in that special calibration objects are used or the object size is too large. In this paper, we introduce a simple calibration method between two sensors using a spherical object. We calculated the sphere center coordinates using four 3-D points selected by RANSAC of the range data of the sphere. The 2-dimensional coordinates of the object center in the camera image are also detected to calibrate the two sensors. Even when the range data is acquired from various angles, the image of the spherical object always maintains a circular shape. The proposed method results in about 2 pixel reprojection error, and the performance of the proposed technique is analyzed by comparing with the existing methods.

• The Journal of the Korea Contents Association
• /
• v.21 no.3
• /
• pp.1-9
• /
• 2021

The hologram pyramid is an application of floating holograms, allowing the observer to see three-dimensional holograms from various angles without wearing wearable devices. Due to the low cost and ease of manufacturing, it has been used in a wide variety of fields as diverse as education, prototyping, showcase, and etc. But, when the observer looks at the hologram from the place where each side of the hologram pyramid is connected, the hologram looks cut and distorted. Also, the observer can see the only hologram of angles viewed head-on from each side. In this paper, we propose a method of generating a hologram image corresponding to the observer's gaze angle by tracking the observer's position and conducting reverse distortion. It provide a hologram of the angle viewed by the observer without cutting and distortion. In addition, the existing method and the proposed method were applied and compared in the hologram pyramid.

• The Journal of Korean Academy of Prosthodontics
• /
• v.55 no.4
• /
• pp.381-388
• /
• 2017

Purpose: Unpredictable shrinkage of zirconia during sintering process causes discrepancy. Therefore, there have been attempts to reduce discrepancy by milling zirconia after sintering. However, due to the hardness of sintered zirconia, milling takes longer time, causes damage to the machine and causes chip formation. With customized zirconia block using the mean dimension of prepared natural dentition, it is expected to overcome these shortcomings. Materials and methods: The mean dimension of prepared natural dentition was analyzed as STL file after scanning of prepared teeth treated at SNUDH. The transverse, frontal and sagittal planes were set using Mimics and Photoshop. 3D volume was projected on each plane, and the outer line was measured through external tangent line, and the inner line was measured through inflection point of tangent line. Results: The mean height of prepared incisal (N = 57) is $6.60{\pm}1.05mm$, mesiodistal length is $2.98{\pm}0.73mm$, buccolingual length is $2.04{\pm}0.73mm$. The mean height of prepared premolar (N = 15) is $5.37{\pm}1.49mm$, mesiodistal length is $4.10{\pm}1.78mm$, buccolingual length is $5.86{\pm}1.55mm$. And the mean height of prepared molar (N = 13) is $5.11{\pm}1.29mm$, mesiodistal length is $6.80{\pm}1.18mm$, buccolingual length is $7.34{\pm}1.40mm$. Conclusion: Using the mean dimension of prepared natural dentition, it is expected to be able to fabricate customized zirconia block.