• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.300-307
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• 2005

Steel Reinforced Concrete (SRC) composite column has several advantage such as excellent durability, rapid construction, reduction of column section. Due to these aspect, applications of SRC columns to bridge piers are continuously increasing. For the design of relatively large SRC columns for bridge piers, it is necessary to check the current design provisions which were based on small section having higher steel ratio. In this study, seven concrete encased composite columns were fabricated and static tests were performed. Embedded steel members were a H-shape rolled beam and a partially filled steel tube. Based on the test results, the ultimate strength according to section details and local behavior were estimated. For the analysis of inelastic behavior of the SRC column, the cracked section stiffness of the columns was evaluated and compared with calculations. The stiffness of the cracked section showed that 25% of the initial value and this stiffness reduction occurred at 85% of the ultimate load in the experiments.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.447-452
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• 2005

Nowadays domestic demands for urban EMUs are gradually increased due to traffic jams and environmental problems. Therefore it has been required to make sure of manufacturing quality and to acquire cost effective bogie frames through mass production. One of the major functions of bogie frames is to guarantee the static strength and durability. In this research, the comparison between FE analysis and actual load test results is performed for the bogie frame, which is manufactured by Rotem Company. The results show that the standardized bogie frame meets the strength requirements of domestic regulations.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.2
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• pp.282-287
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• 2010

This paper gives a description of an experimental study of the ultrasonic welding of metals. In ultrasonic metal welding, high frequency vibrations are combined with pressure to join two materials together quickly and securely, without producing significant amount of heat. Ultrasonic metal welder consists of Transducer, Booster, and horn that are designed very accurately to get the natural frequencies and vibration mode. In this study, The horn was designed and analyzed the natural frequency by the modal analysis and harmonic analysis. And using a fiber optic sensor, we measured the amplitude and analyzed the Fast Fourier Transformed result. Using the horn, Ultrasonic metal welding between Cu sheet and Cu sheet of 0.1mm thickness was accomplished under the optimal conditions of static pressure 0.15MPa, vibration amplitude 30% and welding time of 0.28s. This result can be used for ultrasonic metal welding in manufacturing industry.

• Journal of Korean Association for Spatial Structures
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• v.15 no.4
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• pp.91-98
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• 2015

This paper has proposed a reinforcing method for damaged RC columns with SRF sheets and Aramid rods. In order to verify the effectiveness and performance, two original columns and two reinforced columns with SRF sheets and Aramid rods were developed and tested under lateral cyclic displacement and a constant axial load. The test showed that the improvement of energy dissipation capacity was increased in terms of strength and ductility. In addition, an analytical modeling of the standard specimens was proposed using Response-2000 and ZeusNL program. The results of analytical and experimental studies for two standard columns were compared in terms of loading-displacement curve and energy dissipation capacity based on the nonlinear static analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.5
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• pp.617-624
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• 2007

This paper presents a novel quadstable monolithic mechanism (QsMM) which provides four stable equilibrium positions within its operation range. The quadstable mechanism has been realized from the use of both X- and Y-directional bistable structures which use curved snapping beams. A millimeter-scale brass mechanism was fabricated by ultra-precision milling to test the quadstability and the displacement-load behavior, and the prototype clearly demonstrated four distinct stable positions in its millimeter-scale planar operation. We discuss the design concept, finite element simulation for static and transient responses, fabrication by ultra-precision milling, and experimental measurement of the proposed quadstable mechanism.

• New & Renewable Energy
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• v.4 no.3
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• pp.45-50
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• 2008

GFRP based composite rotor blades were developed for 750 kW & 2 MW wind turbines. The blade sectional geometry was designed to have a general shell-spar and shear web structure. For verifying the structural safety under all relevant extreme loads specified in the GL guidelines, the structural analysis of the rotor blades was performed using commercial FEM codes. The static load carrying capacity, blade tip deflections and natural frequencies were evaluated to satisfy the strength and stability requirements. Full-scale proof tests of rotor blades were carried out with optical fiber sensors for real-time condition monitoring. Finally, the prototype of each rotor blade passed all proof tests for GL certification.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.299-302
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• 2008

GFRP based composite rotor blades were developed for 750kW & 2MW wind turbines. The blade sectional geometry was designed to have a general shell-spar and shear web structure. For verifying the structural safety under all relevant extreme loads specified in the GL guidelines, the structural analysis of the rotor blades was performed using commercial FEM codes. The static load carrying capacity, blade tip deflections and natural frequencies were evaluated to satisfy the strength and stability requirements. Full-scale proof tests of rotor blades were carried out with optical fiber sensors for real-time condition monitoring. Finally, the prototype of each rotor blade passed all proof tests for GL certification.

• 기술발표회
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• s.2006
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• pp.75-85
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• 2006

The project comprised the construction of the new oil pier and associated topside facilities and demolition of exiting south pier. The site is located approximately 33km south of Kuwait city at MAA refinery. The approach trestle and berth structures of the new oil pier were designed to be supported by steel tubular piles Total 2,480 numbers of piles(795 piles at Approach Trestle, 1187 piles at Berth 1 -4 and 498 piles at Berth 5-6) had to be driven through the calcareous silty sand In this study, the design procedures for offshore steel pipe piles, evaluation for the compression and tension capacities by static and dynamic load test and effective driving criteria by the final set values are discussed

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.60-66
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• 1999

Generally, bogie frame for EMU consists of side frame, crossbeam and transom. Among the main frame structure which has been produced in our company, crossbeam and transom have been made of circular shaped tube. In this un, welding process between circular crossbeam and circular transom is complicated and takes much time. To improve this problem, new rectangular tube shaped transom is adopted. In this paper, the processes and results of finite element analysis are described, which was carried out to evaluate the strength of new bogie frame according to UIC, JIS, KS code. FEA results show that the new bogie frame has sufficient static and fatigue strength. Comparing the FEA results with load test results should follow and further study for evaluating the fatigue strength will be pursued in future.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.232-237
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• 1999

The standardization urban transit project has been started by government and the Korean standard electrical railcar has been designed. The bodyshell of standard railcar is made of aluminium alloy. In the present paper, the design of its bodyshell is evaluated in the viewpoint of strength analysis. The loading condition is based on the 'Test Methods of Static Load for Body Structure of Electrical Multiple Unit', standard specification. The bodyshell of Korean standard EMU consist of longitudinal extrusion members which are double-skin structure type. For the purpose of security and lightening we decided the section of the aluminium carbody through the size optimization in this paper Hereafter this paper will contribute to the shape optimization.