• Structural Engineering and Mechanics
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• v.36 no.4
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• pp.463-479
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• 2010

Based on damage accumulation of multi-grid composite walls, a method of dynamic reliability estimations is proposed. The multi-grid composite wall is composed of edge frame beam, edge frame columns, grid beams, grid columns and filling blocks. The equations including stiffness, shear forces at filling blocks cracking and multi-grid composite walls yielding, ultimate displacement, and damage index are obtained through tests of 13 multi-grid composite wall specimens. Employing these equations in reliability calculations, procedures of dynamic reliability estimations based on damage accumulation of multi-grid composite walls subjected to random earthquake excitations are proposed. Finally the proposed method is applied to the typical composite wall specimen subjected to random earthquake excitations which can be specified by a finite number of input random variables. The dynamic reliability estimates, when filling blocks crack under earthquakes corresponding to 63% exceedance in 50 years and when the composite wall reach limit state under earthquakes corresponding to 2-3% exceedance in 50 years, are obtained using the proposed method by taking damage indexes as thresholds. The results from the proposed method which show good agreement with those from Monte-Carlo simulations demonstrate the proposed method is effective.

• Composites Research
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• v.16 no.5
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• pp.1-6
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• 2003

As the use of composites has become popular in recent years, the design of the composite joints has become a very important research area because the structural efficiency of the composite structure is determined by its joints, not by its basic structures. In this paper, presented comparisons of numerical results by the FAI(Failure area index) method[9] and measured data for a various geometric shapes and stacking sequence justify the validity of the FAI method. The FAI method is shown to produce very favorable comparisons with measured failure loads of mechanically fastened composite joints with the difference well within 9.96% for all II cases investigated.

• Korean Journal of Construction Engineering and Management
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• v.11 no.5
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• pp.41-52
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• 2010

Even though REITs (Real Estate Investment Trusts) are listed on the stock market, REITs have characteristics that allow them to invest in real estate and financing for real estate development. Therefore REITs is related with stock market and construction business and real estate business. Using time-series analysis, this study analyzed REITs in relation to construction businesses, real estate businesses, and the stock market, and derived influence factor of REITs. We used the VAR (vector auto-regression) and the VECM (vector error correction model) for the time-series analysis. This study classified three steps in the analysis. First, we performed the time-series analysis between REITs and construction KOSPI(The Korea composite stock price index) and the result showed that construction KOSPI influenced REITs. Second, we analyzed the relationship between REITs and construction commencement area of the coincident construction composite index, office index and housing price index in real estate business indexes. REITs and the housing price index influence each other, although there is no causal relationship between them. Third, we analyzed the relationship between REITs and the construction permit area of the leading construction composite index. The construction permit area is influenced by REITs, although there is no causal relationship between these two indexes, REITs influenced the stock market and housing price indexes and the construction permit area of the leading composite index in construction businesses, but exerted a relatively small influence in construction starts coincident with the composite office indexes in this study.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.151-158
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• 2000

In this paper, It is presented that concrete-filled composite piers have large energy-absorption capacity and high strength and stiffness on account of mutual confinement between the steel plate and filled-in concrete. Concrete-filled composite columns were tested to failure under axial compression and cyclic lateral loading. Displacement ductility index obtained by using the load-displacement relation has been increased with the increment of filled-in concrete length, while it has been decreased according to the incrementation of width-thickness ratio, slenderness ratio and the number of loading cycles. Structural behavior and ductility index estimated for the seismic design showed that composite piers could be used as a very efficient earthquake-resistant structural member. The response modification factor could be re-evaluated for concrete-filled composite piers.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.9-16
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• 2001

In this paper, general design process for Tracked Fighting Vehicle has been suggested. Stress analysis and optimal design for ply angle of IFV's composite upper hull has been calculated using KMA CIFV and it is contained exploratory development of design process. In this point, this paper applied composite to IFV's upper hull. Finite element mesh has been made using Matlab program, and we have analyzed stress based on the given material properties and ply arrangement. For each load condition, load distribution in plane and failure index are calculated by using Tasi-Hill criterion, which is composite failure criterion and analyzing change of failure index as change of ply angle. Finally, optimal ply angles of upper hull are calculated using KMA CIFV. We can estimate the decrease of weight for IFV's upper hull.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.21-27
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• 2018

In this paper the laminate design parameters are researched to maximize the performance index of a composite pressure vessel. To maximize the performance index, the three design variables that the thickness of each of helical and hoop layers and the length of hoop layer are considered under the assumption of fixed internal space. To optimize the variables, the response surface method is introduced for construction of the surrogate model and the ANOVA(analysis of variance) is performed to evaluate the effects of the variables. The optimization problem is formulated to maximize performance index under the burst pressure constraint. To verify the effectiveness of the research, numerical analyses are performed for the optimum model.

• The Korean Journal of Applied Statistics
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• v.29 no.1
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• pp.243-255
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• 2016

The developed composite index has limits to estimate and predict economic status due to economic pattern change and the response change of explanatory variables. A higher precedence individual indicators should be selected to predict the future accurately. In this study, effectiveness of Jeju Island precedence indicators consists of constituents in the area, the consumer price index, services production index, mining and manufacturing production index. The average temperature of Seogwipo and credit card purchase amount is reviewed as an economic turning point consideration and time lag correlation analysis with real data. In addition, we suggest the proper reference cycle in Jeju composite precedence index and evaluate the configuration in leading indicators for Jeju by comparing national economic indicators. Based on the derived results, the current problems of Jeju Island precedence indicators will be illustrated and the improvement methods to estimate a regional composite index will be suggested.

• Journal of Korea Technology Innovation Society
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• v.8 no.2
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• pp.583-604
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• 2005

The future will see all industries become technology-driven in the competitive global market place. Firms with deep technological roots and innovation strategies have some advantages. In this situation widely used scoring approach is not enough to evaluate technology's relative competitiveness and to assign relative ranking category. Therefore, a more useful and comprehensive approach, which is called technology composite index, is needed to complement and enhance the existing scoring approach. In this research, factor analysis is applied to determine the common factors and to estimate associated weights. And technology composite index is used to measure the technology's relative strength and also to assign its ranking category instead of technology scoring.

• Journal of Intelligence and Information Systems
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• v.1 no.2
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• pp.103-121
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• 1995

This study proposes a artificial neural network method to predict the time to buy and sell the stocks listed on the Korea Composite Stock Price Index(KOSPI). Four types (NN1, NN2, NN3, NN4) of independent networks were developed to predict KOSPIs up/down direction after four weeks. These networks have a difference only in the length of learning period. NN5 - arithmetic average of four networks outputs - shows an higher accuracy than other network types and Multiple Linear Regression (MLR), and buying and selling simulation using systems outputs produces higher reture than buy-and-hold strategy.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.3
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• pp.273-280
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• 2019

Carbon fiber composite laminate has been widely used in the area of sports applications such as race car, golf club, fishing rods, yacht. In this study, carbon fiber composite laminate was used in the rear upright of leisure purposed small size single-seat electric race car to reduce its unsprung mass of suspension system. The focus of this research is to investigate in finding optimal stacking lay-up of rear upright laminated with carbon fiber composite in the early design phase. Forces transferred from circuit road to rear upright were estimated through MBD(Multi-Body Dynamics)model of the rear suspension geometry. To evaluate the strength of the rear upright laminated with carbon fiber composite which generally behaves in an anisotropic or orthotropic manner, FEA(Finite Element Analysis) model suitable for composite materials was built followed by its strength was evaluated depending on different stacking lay-up. The result showed that Symmetric stacking lay-up [$45^{\circ}/-45^{\circ}/90^{\circ}/0^{\circ}$]s for frontal area and symmetric stacking lay-up with 1mm aluminum core [$45^{\circ}/-45^{\circ}/90^{\circ}/Core$]s for rear area were most suitable of 16 lay-up cases from the side of both strength based on Tasi-wu failure index and weight.