• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.116-120
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• 2004

A metal flaperon of a supersonic aircraft including the ribs, and skins was re-designed with a graphite/epoxy composite material to evaluate the weight saving effect. MSC/NASTRAN was used for the finite element analysis. The safety of the composite structures were evaluated in terms of the failure index, section cut, buckling, bearing/bypass and durability and damage tolerance analysis. After the application of the composite material, total weight saving of 25.6 pounds was achieved.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.3
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• pp.292-298
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• 2017

Numerical analysis for various design parameters should be preceded by optimal design of composite materials. Numerous studies have been conducted on the bolting of interconnecting beams. In this study, the response surface method was applied to optimize the design of bolted joints connected by laminated wood composite beams. The response surface was created by combining the FEA code for composite analysis and the algorithm for forming the response surface. Optimization on this response surface was performed with a genetic algorithm to derive the results. The determination of the optimum bolt-hole position for the connection of composite beams is an optimization problem. Tsai-Wu composite failure index, maximum deflection, and simple von Mises stress are set as the objective functions. It has been proved that the design results of the optimized bolt-hole are superior to the design performance of the existing conventional bolt-hole position.

• KIEE International Transactions on Power Engineering
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• v.5A no.3
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• pp.286-292
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• 2005

As the power industry moves towards open competition, there has been a call for methodology to evaluate power system reliability by using composite interruption cost. This paper presents algorithms to evaluate the interruption cost of distribution power systems by taking into consideration the failure source and the composite customer interruption cost. From the consumer's standpoint, the composite customer interruption cost is considered as the most valuable index to estimate the reliability of a power distribution system. This paper presents new algorithms that consider the load by customer type and failure probability by distribution facilities while calculating the amount of unserved energy by customer type. Finally, evaluation results of unserved energy and system interruption cost based on composite customer interruption cost are shown in detail.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.272-277
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• 2010

In respect complication of group, rate of arrearage in domestic bank is composed of various factors. This paper studies focus on estimating the determinants of the rate of arrearage in domestic bank using panel data model. The volume of analysis consist of 3 groups(loaned patterns of enterprise, housekeeping, credit card). Analyzing period be formed over a 54 point(2005. 1~ 2009. 06). In this paper dependent variable setting up rate of arrearage in domestic bank, explanatory(independent) variables composed of the consumer price index, composite stock price index, rate of exchange, the coincident composite index, national housing bonds and employment rate. The result of estimating the rate of arrearage in domestic bank provides empirical evidences of significance positive relationships between the consumer price index However this study provides empirical evidences of significance negative relationships between the coincident composite index and the composite stock price index. The explanatory variables, that is, rate of exchange, national housing bonds and the employment rate are non-significance variables of negative factor. Implication of these findings are discussed for content research and practices.

• Steel and Composite Structures
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• v.14 no.2
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• pp.105-120
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• 2013

Flexural behavior of thin walled steel-concrete composite sections as cross sections for beams is investigated by conducting an experimental study supported by applicable analytical predictions. The experimental study consists of testing up to failure, simply supported beams of effective span 1440 mm under two point loading. The test specimens consisted of composite box and channel (with lip placed on tension side and compression side) sections, the behavior of which was compared with companion empty sections. To understand the role of shear connectors in developing the composite action, some of the composite sections were provided with novel simple bar type and conventional bolt type shear connectors in the shear zone of beams. Two RCC beams having equivalent ultimate moment carrying capacities as that of composite channel and box sections were also considered in the study. The study showed that the strength to weight ratio of composite beams is much higher than RCC beams and ductility index is also more than RCC and empty beams. The analytical predictions were found to compare fairly well with the experimental results, thereby validating the applicability of rigid plastic theory to cold-formed steel concrete composite beams.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.7
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• pp.643-649
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• 2014

In order to demonstrate the possibility of applying an ionic polymer metal composite (IPMC) to a finger exoskeleton, pinching motion analysis was performed for a thumb-index finger dummy actuated by IPMC actuators. The IPMC actuators of 5mm in width and 40mm in length with 2.4mm thickness generated 1.52N of blocking force for the applying voltage of 4.0V. Three actuators were installed on the three rotary joint of an index finger, and one actuator was installed on one proximal joint. Positions of each joint and finger tip were recorded on the video camera, and motion was analyzed. Power supply to the index finger actuators preceded power supply to the thumb actuator, and key pinching motion was accomplished in 180s. Tip pinching was accomplished in 135s as power supply to the thumb preceded power supply to the index finger.

• Journal of the Korean housing association
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• v.21 no.6
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• pp.99-108
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• 2010

This study investigated the environmental indices in environmental administration, and to presents how to develop a sustainable environmental evaluation index. The index should be used to evaluate composite plans in the environmental aspects as well as means for setting goals of basic plans for the environment and its management. Specifically, the goals of composite plans are to check environments and land use frame, and evaluate individual measures (public projects). Environment policies are required to be 'a policy creating a clean environment' from 'a policy of environment regulation'. For the organization of a basic framework of environment policies, five topics are needed to be considered, such as the clarification of the idea of environment, establishment of environment regulations, environment management plan, plan to support civilian's action, and local government's efforts for the global matters of environment. For the amenity environments, people should expand their environmental behavior based on their voluntary intentions in transformation of personal life styles, projects with less load on the environment, development of environmentally-friendly projects with consideration for their impact on the earth. This study suggests that they should put more efforts into the development and implementation of useful environmental indices which effectively analyse the regional character to protect the natural ecology and create an sustainable environment with wide coverage.

• Earthquakes and Structures
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• v.23 no.5
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• pp.445-462
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• 2022

To investigate and evaluate the seismic damage behaviors of steel reinforced recycled concrete (SRRC) filled circular steel tube composite columns, in this study, the cyclic loading tests of 11 composite columns was carried out by using the load-displacement joint control method. The seismic damage process, hysteretic curves and performance indexes of composite columns were observed and obtained. The effects of replacement rates of recycled coarse aggregate (RCA), diameter thickness ratio, axial compression ratio, profile steel ratio and section form of profile steel on the seismic damage behaviors of composite columns were also analyzed in detail. The results show that the failure model of columns is a typical bending failure under the combined action of horizontal loads and vertical loads, and the columns have good energy dissipation capacity and ductility. In addition, the replacement rates of RCA have a certain adverse effect on the seismic bearing capacity, energy consumption and ductility of columns. The seismic damage characteristics of composite columns are revealed according to the failure modes and hysteretic curves. A modified Park-Ang seismic damage model based on the maximum displacement and cumulative energy consumption was proposed, which can consider the adverse effect of RAC on the seismic damage of columns. On this basis, the performance levels of composite columns are divided into five categories, The interlayer displacement angle and damage index are used as the damage quantitative indicators of composite columns, and the displacement angle limits of composite columns at different performance levels under 80% assurance rate are calculated as 1/105, 1/85, 1/65, 1/28, and 1/25 respectively. On this basis, the damage index limits corresponding to each performance level are calculated as 0.045, 0.1, 0.48, 0.8, and 1.0 respectively. Finally, the corresponding relations among the performance levels, damage degrees, interlayer displacement angles and damage indexes of composite columns are established. The conclusions can provide reference for the seismic design of SRRC filled circular steel tube composite columns, it fills the vacancy in the research on seismic damage of steel reinforced recycled concrete (SRRC) filled circular steel tube composite columns.

• Composites Research
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• v.30 no.4
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• pp.229-234
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• 2017

Generally, joints are the weakest part in the composite structures. Composite joints can be classified into adhesive joints and mechanical joints, and mechanical joints are mainly used in areas less sensitive to environmental conditions. In this paper, the failure loads of composite mechanical joints with five different stacking angles are tested and predicted. Finite element analysis of mechanical joints were performed and failure loads were predicted by the FAI(Failure Area Index) method using Tsai-Wu and Yamada-Sun failure criteria, and the predicted failure loads were compared with experimental results. From the experiment and analysis, the failure loads of the mechanical joints were decreased as the ratio of 0 degree layer was low and they could be predicted within 13.03% using the FAI method and Yamada-Sun failure criteria.

• Composites Research
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• v.22 no.2
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• pp.7-13
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• 2009

With the wide application of fiber-reinforced composite material in aero-structures and mechanical parts, the design of composite joint have become a very important research area because they are often the weakest areas in composite structures. In this paper, the failure strengths of the hybrid composite joints which were composed of a combination of an adhesive joint and a mechanical joint were evaluated and predicted. The 10 hybrid joint specimens which have different w/d, e/d and adherend thickness were manufactured and tested. The damage zone theory and the failure area index method were used for the failure prediction of the adhesive joint and the mechanical joint, respectively and the hybrid joints were assumed to be failures if either of the two failure criteria was satisfied. From the results of experiments and analyses, the failure strengths of the hybrid joints could be predicted to within 25.5%.