• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.12 no.3
• /
• pp.116-129
• /
• 2000

The interaction of incident monochromatic waves with a tensioned, flexible, circular membrane submerged horizontally below free surface is investigated in the frame of three-dimensional linear hydro-elastic theory. The velocity potential is split into two parts i.e. the diffraction potential representing the scattering of incident waves by a rigid circular disk and the radiation potential describing motion induced waves by elastic responses of flexible membrane. The fluid domain is divided into three regions, and the diffraction and radiation potentials in each region are expressed by the Fourier Bessel series. The displacement of circular membrane is expanded with a set of natural functions, which satisfy the membrane equation of motion and boundary conditions. The unknown coefficients in each region are determined by applying the continuity of pressure and normal velocity at the matching boundaries. The results show that various types of wave focusing are possible by controlling the size, submergence depth, and tension of membrane.

• Journal of KIISE
• /
• v.44 no.4
• /
• pp.392-398
• /
• 2017

The point-cloud representation of an object is performed by scanning a space through a laser scanner that is extracting a set of points, and the points are then integrated into the same coordinate system through a registration. The set of the completed registration-integrated point clouds is classified into meaningful regions, shapes, and noises through a mathematical analysis. In this paper, the aim is the matching of a curved area like a cylinder shape in 3D point-cloud data. The matching procedure is the attainment of the center and radius data through the extraction of the cylinder-shape candidates from the sphere that is fitted through the RANdom Sample Consensus (RANSAC) in the point cloud, and completion requires the matching of the curved region with the Catmull-Rom spline from the extracted center-point data using the Principal Component Analysis (PCA). Not only is the proposed method expected to derive a fast estimation result via linear and curved cylinder estimations after a center-axis estimation without constraint and segmentation, but it should also increase the work efficiency of reverse engineering.

• 전자공학회논문지 IE
• /
• v.48 no.4
• /
• pp.61-68
• /
• 2011

As business management has a high level of dependence on Informational Technology (IT), protecting assets of a company from disaster is one of the most important thing that IT operating managers should consider. Because data or information is a major source of operation of the company, data security is the first priority as an aspect of continuity of business management. Therefore, this paper will realize disaster recovery system, which is suspended because of disaster, based on cloud computing system. Realized High Available Replicate System applied a method of multi thread target database to improve Replicate performance, and real time synchronize technology can improve efficiency of network. From Active to Active operation, it maximizes use of backup system, and it has a effect to disperse load of source database system. Also, High Available Replicate System realized consistency verification mechanism and monitoring technique. For Performance evaluation, High Available Replicate System used multi thread method, which shows more than threefold of replicate performance than single thread method.

• Journal of Broadcast Engineering
• /
• v.25 no.3
• /
• pp.439-448
• /
• 2020

In this paper, we propose a modified optimization algorithm for point cloud matching of multi-view RGB-D cameras. In general, in the computer vision field, it is very important to accurately estimate the position of the camera. The 3D model generation methods proposed in the previous research require a large number of cameras or expensive 3D cameras. Also, the methods of obtaining the external parameters of the camera through the 2D image have a large error. In this paper, we propose a matching technique for generating a 3D point cloud and mesh model that can provide omnidirectional free viewpoint using 8 low-cost RGB-D cameras. We propose a method that uses a depth map-based function optimization method with RGB images and obtains coordinate transformation parameters that can generate a high-quality 3D model without obtaining initial parameters.

• Journal of KIISE:Databases
• /
• v.29 no.1
• /
• pp.27-33
• /
• 2002

There are two significant drawbacks in triple image indexing; one is that is cannot support concept-based image retrieval and the other is that it fails to allow disjunctive labeling of images. To remedy the drawbacks, we propose a new technique supporting a concept-based retrieval against images indexed by indefinite fuzzy triples (I-fuzzy triples). The I-fuzzy triples allow not only a disjunctive image labeling, but also a concept-based matching against images labeled disjunctively. The disjunctive labeling is based on the expended closed world assumption and the concept-based image retrieval is based on fuzzy matching. In this paper, we also propose a concept-based query evaluation against the image database to extract desired answers with the degree of certainty $\alpha$$\in$[1,0].

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.40 no.6
• /
• pp.247-252
• /
• 2003

In this paper, we have designed and fabricated a broadband 2-stage MMIC amplifier. Broadband characteristics could be obtained by compensated matching networks in a 2-stage amplifier design. This method is compensating low gains at lower frequencies in the 1st-stage with higher gains at lower frequencies in the 2nd- stage and then finally flat gains are obtained in the wide frequency ranges. Also, we have obtained not only broadband characteristics but also high gain using compensation matching network. The fabricated amplifier is measured by attaching on the test PCB(Printed Circuits Board). The measurement results are bandwidth of 1.1~2.8 GHz, S$_{21}$ gain of 11.1$\pm$0.3 ㏈ and P1㏈ of 12.6 ㏈m at 2.4 GHz.

• KIPS Transactions on Software and Data Engineering
• /
• v.3 no.8
• /
• pp.309-314
• /
• 2014

To generate a complete 3D model from depth images of multiple RGB-D cameras, it is necessary to find 3D transformations between RGB-D cameras. This paper proposes a convenient view calibration technique using a spherical object. Conventional view calibration methods use either planar checkerboards or 3D objects with coded-pattern. In these conventional methods, detection and matching of pattern features and codes takes a significant time. In this paper, we propose a convenient view calibration method using both 3D depth and 2D texture images of a spherical object simultaneously. First, while moving the spherical object freely in the modeling space, depth and texture images of the object are acquired from all RGB-D camera simultaneously. Then, the external parameters of each RGB-D camera is calibrated so that the coordinates of the sphere center coincide in the world coordinate system.

• Progress in Medical Physics
• /
• v.12 no.2
• /
• pp.177-184
• /
• 2001

The goal of radiation treatment is to deliver a prescribed radiation dose to the target volume accurately while minimizing dose to normal tissues. Due to inaccurate placement of field and shielding block and patient's movement, there could be displacement errors between the planed and treatment regions. In order to verify the location of radiation treatment, we in this study developed the registration algorithm of the x-ray simulator images and portal images and quantified the inaccuracy in terms of shift, scale and rotation. The algorithm for registration of pairs of radiation fields consists of the alignment of pairs of radiation images by points matching and field displacement analysis by field boundary matching. In the first step, paired surface landmarks are matched to calculate the transformation parameters (scale, rotation and shift) using the corresponding line pairs which are created by connecting two landmarks of each image. In the next step, portal field boundary is extracted and then the two field boundaries are matched by the $\rho$-$\theta$ technique. Applying the phantom portal images, detection errors were calculated to be less than 2mm in translation, 1$^{\circ}$ in rotation and 1% in scale. In conclusion, we quantitatively analyzed the displacement error of x-ray simulator images and portal images. The present results could contribute to the study of the radiation treatment verification.

• The KIPS Transactions:PartB
• /
• v.11B no.2
• /
• pp.141-148
• /
• 2004

The ground positions and elevations information called DEMs(Digital Elevation Models) which are extracted from the stereo aerial photographs and/or satellite images using image matching method have the natural errors caused by variant environments. This study suggests the method to evaluate DEMs using correlation values between the reference and the target DEMs. This would be strongly helpful for experts to correct these errors. To evaluate the whole area of DEMs in the horizontal and vertical errors, the target cell is matched for each reference cell using the correlation values of these two cells. When the target cell is matched for each reference cell, horizontal and vertical error was calculated so as to help experts to recognize a certain area of DEMs which should be corrected and edited. If the correlation value is low and tile difference in height is high, the target cell will be candidated as changed or corrupted cell. When the area is clustered with those candidated cells, that area will be regarded as changed or corrupted area to be corrected and edited. Using this method, the evaluation for all DEM cells is practicable, the horizontal errors as well as vertical errors is calculable and the changed or corrupted area can be detected more efficiently.

• Progress in Medical Physics
• /
• v.25 no.3
• /
• pp.167-175
• /
• 2014

The purpose of this study is to evaluate the variation of the dose which is delivered to the patients with glottis cancer under IMRT (intensity modulated radiation therapy) by using the 3D registration with CBCT (cone beam CT) images and the DIR (deformable image registration) techniques. The CBCT images which were obtained at a one-week interval were reconstructed by using B-spline algorithm in DIR system, and doses were recalculated based on the newly obtained CBCT images. The dose distributions to the tumor and the critical organs were compared with reference. For the change of volume depending on weight at 3 to 5 weeks, there was increased of 1.38~2.04 kg on average. For the body surface depending on weight, there was decreased of 2.1 mm. The dose with transmitted to the carotid since three weeks was increased compared be more than 8.76% planned, and the thyroid gland was decreased to 26.4%. For the physical evaluation factors of the tumor, PITV, TCI, rDHI, mDHI, and CN were decreased to 4.32%, 5.78%, 44.54%, 12.32%, and 7.11%, respectively. Moreover, $D_{max}$, $D_{mean}$, $V_{67.50}$, and $D_{95}$ for PTV were increased or decreased to 2.99%, 1.52%, 5.78%, and 11.94%, respectively. Although there was no change of volume depending on weight, the change of body types occurred, and IMRT with the narrow composure margin sensitively responded to such a changing. For the glottis IMRT, the patient's weight changes should be observed and recorded to evaluate the actual dose distribution by using the DIR techniques, and more the adaptive treatment planning during the treatment course is needed to deliver the accurate dose to the patients.