• Communications of the Korean Mathematical Society
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• v.13 no.3
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• pp.539-544
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• 1998

Let (M, g) be a noncompact complete Riemannian manifold of dimension n $\geq$ 3 with scalar curvature S, which is close to O. With conditions on a conformal invariant and scalar curvature of (M, g), we show that there exists a conformal metric (equation omitted), near g, whose scalar curvature (equation omitted) = 0 by gluing solutions of the corresponding partial differential equation on each bounded subsets $K_{i}$ with ∪$K_{i}$ = M.

• Honam Mathematical Journal
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• v.44 no.1
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• pp.62-77
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• 2022

This study presents an 𝛼-Sasakian structure on the product manifold M₁ × 𝛽(I), where M₁ is a Kähler manifold with an exact 1-form, and 𝛽(I) is an open curve. It then defines a new type warped product metric to study the warped product of almost Hermitian manifolds with almost contact metric manifolds, contact metric manifolds, and K-contact manifolds.

• Journal of Ocean Engineering and Technology
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• v.23 no.1
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• pp.7-15
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• 2009

The aim of this study was to survey the effects of the beachface gradient on 3-D currents around the open inlets of submerged breakwaters. First, the numerical model was validated by a comparison with existing experimental data. This model is able to consider the flow through a porous medium with inertial, laminar, and turbulent resistance terms, i.e. simulate directly WAve?Structure?Seabed/Sandy beach interaction, and can determine the eddy viscosity with a LES turbulent model in a 3-Dimensional wave field (LES-WASS-3D). Using the numerical results of this model, the 3-D currents around the open inlets of submerged breakwaters were examined in relation to the beachface gradient. Moreover, the wave height distribution and mean flow around them are also discussed, as well as the distribution of the wave breaking points over the crest.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.63-65
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• 2014

Open source software has a feature that offers its service by the subscription method without getting a license fee. Therefore, this business style needs a different form of estimate criteria from other proprietary software, which is paid by license fees and maintenance service fees. However, consumers, including the public sector, don't understand this feature. This problem has kept the open source software business from attaining prosperity. I would like to provide a model for the estimate criteria that can apply to the open source software business by investigating and developing various advanced research and market examples.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.12
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• pp.1002-1010
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• 2005

We study on the implementation of reconfigurable position control system which is based on Open Control Platform(OCP) for Unmanned Expedition Vehicles(UEV) in ubiquitous environment. The control system uses hierarchical control structure and OCP structure which contains three layers such as core OCP, reconfigurable control API(Application Programmer Interface), generic hybrid control API. The goal of our research is to implement an UEV control system using advanced software technology. As a specific control problem, we study a transition management problem between PID control and neural network control depending on fault or parameter change of the plant, i.e., UEV. The concept of the OCP-based software-enabled control can provide synergy effect by the integration of software component, middleware, network communication, and control, and thus can be applied to various systems in ubiquitous environment.

• Structural Engineering and Mechanics
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• v.21 no.5
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• pp.591-620
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• 2005

A general analytical model for thin-walled composite beams with an arbitrary open/(or/and) closed cross section and arbitrary laminate stacking sequence i.e., symmetric, anti-symmetric as well as un-symmetric with respect to the mid plane of the laminate, is developed in the first paper. All the mechanical properties, mechanical centre of gravity and mechanical shear centre of the cross section are defined in the function of the geometry and the material properties of the section. A program "fungen" and "clprop" are developed in Fortran to compute all the mechanical properties and tested for various isotropic sections first and compared with the available results. The locations of mechanical centre of gravity and mechanical shear centre are given with respect to the fibre angle variation in composite beams. Variations of bending and torsional stiffness are shown to vary with respect to the fibre angle orientations.

• Journal of Chest Surgery
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• v.22 no.6
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• pp.996-1000
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• 1989

Open heart surgery begun at 1959 in Korea. From that time to 1979, the surgery was performed below 100 cases in a year. However,that was performed above, 1,000 cases in a year from 1981. During the recent three years, i.e., 1985, 1986, and 1987, the annual operative cases were 3614,4503, and 4906, and then the mortality rates were progressively decreased to 6.2%, 5.3 %, and 5.0 %. In these time, overall mortality rate above 1 year old was 5.0 % versus that below 1 year old 17.9 9o in congenital heart diseases. These results are statistically different between two groups. Of the valvular heart disease cases, which occupied 97 % of total acquired heart disease, individual incidence was in mitral 68 %, and aortic 28%. The operative method was mainly valve replacement. Operative mortality for valve surgery in total was 4.4 %. Until 1985, bioprosthetic valve was frequently implanted but mechanical valve has been done more frequently in these days. Coronary artery bypass graft was large portion [67 * 75 %] of open heart surgery in western, but was below 1 % in Korea. However our diet patterns have been changed. Therefore we think the incidence of coronary artery disease will be increased. So we will be familiar to this field.

• Journal of the Semiconductor & Display Technology
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• v.23 no.2
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• pp.19-22
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• 2024

EtherCAT is an Ethernet-based fieldbus system standardized in IEC 61158 and SEMI, and widely used in the fields of factory automation, semiconductor equipment and robotics. In this paper, we summarize the current status of Xenomai real-time framework and RTnet, which are essential for Linux operating systems to operate in real-time, and implement a real-time EtherCAT master system with these open sources. The real-time performance of the implemented EtherCAT master is evaluated according to Intel network controllers 82574L, I219, I210, and I225, respectively. The results show that the implemented EtherCAT master provides precise control performance for control frequencies from 1KHz to 8KHz and similar performance for I219, I210, and I225, and relatively slightly larger jitter for 82574L.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.6
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• pp.445-452
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• 2019

In this study, parallel processing codes of k-means clustering algorithm were developed and implemented in a PC-cluster for unsupervised classification of large satellite images. We implemented intra-node code using multicores of CPU (Central Processing Unit) based on OpenMP (Open Multi-Processing), inter-nodes code using a PC-cluster based on message passing interface, and hybrid code using both. The PC-cluster consists of one master node and eight slave nodes, and each node is equipped with eight multicores. Two operating systems, Microsoft Windows and Canonical Ubuntu, were installed in the PC-cluster in turn and tested to compare parallel processing performance. Two multispectral satellite images were tested, which are a medium-capacity LANDSAT 8 OLI (Operational Land Imager) image and a high-capacity Sentinel 2A image. To evaluate the performance of parallel processing, speedup and efficiency were measured. Overall, the speedup was over N / 2 and the efficiency was over 0.5. From the comparison of the two operating systems, the Ubuntu system showed two to three times faster performance. To confirm that the results of the sequential and parallel processing coincide with the other, the center value of each band and the number of classified pixels were compared, and result images were examined by pixel to pixel comparison. It was found that care should be taken to avoid false sharing of OpenMP in intra-node implementation. To process large satellite images in a PC-cluster, code and hardware should be designed to reduce performance degradation caused by file I / O. Also, it was found that performance can differ depending on the operating system installed in a PC-cluster.

• Journal of Advanced Navigation Technology
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• v.14 no.5
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• pp.737-744
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• 2010

A Social Network Service(SNS) is the best attracting internet business model and serviced in the several countries. The Facebook is the most popular SNS in a foreign country and the Cyworld is most popular one in Korea. In this paper, after investing and analyzing the existing Social Network Services, I present a new OpenU Social Network Service based on Web 2.0 concepts. This is a next generation internet platform which can be communicated with real-time chatting and share d data and talked during seeing data by collaboration functions OpenU's main characteristics and functions by screen design and implementations are explained. And also OpenU's excellence by comparing with other SNSs system is presented.