• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.5 no.1
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• pp.85-100
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• 2001

In this paper we propose a block-type parallel preconditioner for solving large sparse nonsymmetric linear systems, which we expect to be scalable. It is Multi-Color Block SOR preconditioner, combined with direct sparse matrix solver. For the Laplacian matrix the SOR method is known to have a nondeteriorating rate of convergence when used with Multi-Color ordering. Since most of the time is spent on the diagonal inversion, which is done on each processor, we expect it to be a good scalable preconditioner. Finally, due to the blocking effect, it will be effective for ill-conditioned problems. We compared it with four other preconditioners, which are ILU(0)-wavefront ordering, ILU(0)-Multi-Color ordering, SPAI(SParse Approximate Inverse), and SSOR preconditioner. Experiments were conducted for the Finite Difference discretizations of two problems with various meshsizes varying up to 1024 x 1024, and for an ill-conditioned matrix from the shell problem from the Harwell-Boeing collection. CRAY-T3E with 128 nodes was used. MPI library was used for interprocess communications. The results show that Multi-Color Block SOR and ILU(0) with Multi-Color ordering give the best performances for the finite difference matrices and for the shell problem only the Multi-Color Block SOR converges.

• Earthquakes and Structures
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• v.8 no.5
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• pp.1191-1214
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• 2015

The Theory of Plastic Mechanism Control (TPMC) has been recently extended to the case of Eccentrically Braced Frames (EBFs) with inverted Y-scheme, i.e., EBFs with vertical links. In this paper a further validation of the design procedure, based on TPMC, is provided by means of Incremental Dynamic Analyses (IDA) pointing out the fulfilment of the design goal, i.e., the development of a pattern of yielding consistent with the collapse mechanism of global type where all the links are yielded and all the beams are yielded at their ends while all the columns and the diagonal braces remain in elastic range with the only exception of the base sections of first storey columns. In particular, a study case is designed according to both TPMC and Eurocode 8 provisions and the corresponding seismic performances are investigated by both push-over and IDA analyses. The results show the different performances obtained in terms of pattern of yielding, maximum interstorey drift, link plastic rotation demand and sharing of the seismic base shear between the moment-resisting part and the bracing part of the structural system. The seismic performance improvement obtained by means of TPMC, compared to Eurocode 8 provisions, is pointed out.

• Journal of the Korean earth science society
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• v.36 no.5
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• pp.476-483
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• 2015

The high-order Laplacian-type filter, which is capable of providing isotropic and sharp cut-off filtering on the spherical domain, is essential in processing geophysical data. In this study, a spherical high-order filter was designed by combining the Fourier method with finite difference-method in the longitude and latitude, respectively. The regular grid system was employed in the filter, which has uniform angular spacing including the poles. The singularity at poles was eliminated by incorporating variable transforms and continuity-matching boundary conditions across poles. The high-order filter was assessed using the Rossby-Haurwitz wave, the observed geopotential, and observed wind field. The performance of the filter was found comparable to the filter based on the Galerkin procedure. The filter, employing the finite difference method, can be designed to give any target order of accuracy, which is an important advantage being unavailable in other methods. The computational complexity is represented with 2n-1 diagonal matrices solver with n being the target order of accuracy. Along with the availability of arbitrary target-order, it is also advantageous that the filter can adopt the reduced grid to increase computational efficiency.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.110.1-110.1
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• 2014

The optics of Space telescope is one of the major parts of space mission used for imaging observation of astronomical targets and the Earth. These kinds of space mission have a bulky and complex opto-mechanics with a long optical tube, but there are attempts have been made to observe a target with a small satellite in many ways. In this paper, we describe an optical design of a reflecting telescope for use in a CubeSat mission. For this design, we adopt the off-axis segmented method of astronomical observation techniques based on the Ritchey-Chr$\acute{e}$tien type telescope. The primary mirror shape is a rectangle with dimensions of $8cm{\times}8cm$, and a secondary mirror has dimensions of $2.4cm{\times}4.1cm$. The focal ratio is 3 which can obtain a $0.3{\times}0.2$ degree diagonal angle in a $1280{\times}800$ CMOS color image sensor with a pixel size of $3{\mu}m{\times}3{\mu}m$. This optical design can capture a ${\sim}4km{\times}{\sim}2.3km$ area of the earth's surface at 700 km altitude operation. Based on this conceptual design, we will keep trying to study more for astronomical observation with Attitude control system.

• Journal of the Korean Institute of Rural Architecture
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• v.12 no.3
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• pp.19-26
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• 2010

This study is aimed to look into the craftsmanship non-educated constructors in Korean-style secondary stations(Gong-So) of Naepo region which is located in the northwestern Chungcheongnam-do. Although the area was persecuted as one of three cradles of Korean Catholicism, Catholic activities flourished there. The 13 cases of Korean-style secondary stations were selected through a survey report list about modern cultural assets of Chungcheongnam-do published in december 2004. This study examined the methods of plan layout and framework of Gong-So to look into craftsmanship of non-educated constructors, the results are as follows; The methods of plan layout are divided into three types according to existence and arrangement of inner column(Nae-Ju); 'Layout with Nae-Ju' is considered as the primary form of Korean-style Gong-So with using regular Nae-Ju. 'Layout with the different position of the center between Nae-Ju and exterior column(Oe-Ju)' and 'layout without Nae-Ju' is appeared in Korean-style Gong-So which is important to assembly and alter function. The methods of framework are appeared variously according to different plan layout for securing worship space. The unusal beam(Chung-Ryang) is used to solve different spans of altar and narthex. When space was formed widely without Nae-Ju, diagonal members and M letter type rafters are used, they are influenced by the technique of western wooden roof truss.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.4
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• pp.22-27
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• 2000

In this paper, new neural network called dynamic multidimensional wavelet neural network (DMWNN) is proposed. The resulting network from wavelet theory provides a unique and efficient representation of the given function. Also the proposed DMWNN have ability to store information for later use. Therefore it can represent dynamic mapping and decreases the dimension of the inputs needed for network. This feature of DMWNN can compensate for the weakness of diagonal recurrent neural network(DRNN) and feedforward wavelet neural network(FWNN). The efficacy of this type of network is demonstrated through experimental results.

• Earthquakes and Structures
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• v.15 no.2
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• pp.145-153
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• 2018

Extensive reinforced concrete interior beam-column joints with beams of different depths have been used in large industrial buildings and tall building structures under the demand of craft or function. The seismic behavior of the joint, particularly the relationship between deformation and strength in the core region of these eccentric reinforced concrete beam-column joints, has rarely been investigated. This paper performed a theoretical study on the effects of geometric features on the shear strength of the reinforced concrete interior beam-column joints with beams of different depths, which was critical factor in seismic behavior. A new model was developed to analyze the relationship between the shear strength and deformation based on the Equivalent Strut Mechanism (ESM), which combined the truss model and the diagonal strut model. Additionally, this paper developed a simplified calculation method to estimate the shear strength of these type eccentric joints. The accuracy of the model was verified as the modifying analysis data fitted to the test results, which was a loading test of 6 eccentric joints conducted previously.

• International Journal of High-Rise Buildings
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• v.5 no.4
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• pp.319-326
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• 2016

The ingenuity of structural engineers in the field of tall and super-tall buildings has led to some of the most remarkable inventions. During this evolution of structural engineering concepts in the last 100 years, the technical challenges that engineers encountered were extraordinary and the advances were unprecedented. However, as the accomplishments of structural engineers are progressing, the desire for taller and safer structures is also increasing. The diagrid structural system is part of this evolving process as it develops a new paradigm for tall building design combining engineering efficiency and new architectural expression. The first appearances of this type of tall buildings have already been constructed and the interest of both engineering and architectural communities is growing mainly due to the many advantages compared to other structural systems. This paper presents a simple approach on optimizing member sizes for the diagonals of steel diagrid tall buildings. The optimizing method is based on minimizing the volume of the diagonal elements of a diagrid structure. The constraints are coming from the stiffness-based design, limiting the tip deflection of the building to widely accepted regulative limits. In addition, the current paper attempts to open the discussion on the important topic of optimization and robustness for tall buildings and also studies the future of the diagrid structural system.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.4
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• pp.453-465
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• 2005

Purpose: This study was performed to measure the accuracy of adjustable dental impression trays by a scanning laser three-dimensional digitizer. Materials and methods: The metal stock, individual, and adjustable stock trays were used for 60 stone casts(10 casts each) duplicated a resin master model of mandible and maxilla. The type IV dental stone was poured in a vinyl polysiloxane impressions and allowed to set for one hour. The master model and the duplicated casts were digitized using an optical digitizer. The distance between the reference points were measured and analyzed on the graphic image of 3-D graphic software(CATIA version 5.0). The statistical significance of the differences between the groups was determined by a two-way ANOVA. Results : There were no significant differences between the accuracies of the adjustable stock tray and the master model except only anterior arch width on the upper arch and the diagonal arch length and arch length on one side of the lower arch. Conclusion: The adjustable stock trays showed clinically acceptable accuracies of the study cast produced by them.

• Journal of the Korean Society of Safety
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• v.21 no.2 s.74
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• pp.57-62
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• 2006

Recent trends in the construction of building frame feature the use of composite steel concrete members. One of such system, RCS(Reinforced Concrete column and Steel beam) system, is known as a type of system to maximize the structural and economic benefits in the most efficient manner. This paper is focusing on an study of ultimate shear strength estimation of the interior beam-column joints of RCS system, with reinforced concrete column and steel beam. Current design methods as well as the majority of the previous researches for ultimate shear strength of the interior beam-column joint of RCS system are not easy to apply actual manner. There is a need to propose the rational macro models based on analytical approach. In this study, design method variables for interior beam-column joints of RCS system is studied assuming shear resistance of steel web panel, diagonal concrete strut mechanism and truss mechanism. Finally, calculated results based on the proposed design model are compared with test data.