• 소성∙가공
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• 제17권6호
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• pp.436-442
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• 2008

As the structure of a mobile phone becomes thin to catch up with a slim product trend, the structural strength and resistance to shock of TFT-LCD module are getting to be reduced. Hence, TFT-LCD module is the strength reinforced by bezel frame. The bezel frame was produced by the multi hemming processes with several folding parts. The determination of the optimal number of hemming part and structure of bezel frame are very important process parameter to obtain the strength of that. The effect of process parameters on strength of bezel frame was investigated by FEA. Based on the result of FEA, the experiment was performed using manufactured hemming die, the result of the experiment was compared with FEA and verified. Also, three point bending tests were performed to check the strength of bezel frame.

• Elastomers and Composites
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• 제57권2호
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• pp.48-54
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• 2022

A polymeric adhesion promoter was synthesized to improve the adhesive strength of the Ni lead frame/epoxy composite. Poly(itaconic acid-co-acrylamide) (IAcAAM) was prepared by copolymerizing itaconic acid and acrylamide. We compared the adhesive strength between the Ni lead frame and epoxy composite according to the molecular weight of IAcAAM. The molecular weight of IAcAAM was controlled using an initiator, which made it possible to use IAcAAM in the epoxy molding compound (EMC) manufacturing process by modulating the melting temperature. The adhesive strength of Ni lead frame/epoxy composite increased with the addition of IAcAAM to the epoxy composite. In addition, as the molecular weight of IAcAAM increased, the adhesive strength of the Ni lead frame/epoxy composite slightly increased. We confirmed that IAcAAM with an appropriate molecular weight can be used in the EMC manufacturing process and increase the adhesive strength of the Ni lead frame/epoxy composite.

• 한국지진공학회논문집
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• 제17권6호
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• pp.293-303
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• 2013

This paper deals with steel braced frame as increasing the lateral strength and ductility in order to seismic retrofit of existing buildings and discusses the designing criteria and calculation method of retrofitted buildings. The addition of steel braced frame can be effective for increasing the lateral strength and ductility of existing buildings. However, There is a problem in utilizing this method. It is the approach to provide an adequate connection between the existing RC frame and the installed steel braced frame, because global strength by failure mode(three type) depends on detail of connection and strength of existing RC frame. So, the designer must be confirmed if it satisfies the required performance or not. Failure mode of type I is the most appropriate for increasing the lateral strength and ductility. Seismic performance evaluation and strength calculation of seismic retrofit are performed by guideline by KISTEC(Korea Infrastructure Safety & Technology)'s "seismic performance evaluation and rehabilitation of existing buildings" and Japan Building Disaster Prevention Association. Buildings are modeled and non-linear pushover analysis are performed using MIDAS program.

• 한국산학기술학회논문지
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• 제13권11호
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• pp.4956-4962
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• 2012

자동차의 다양한 부품 중 자동차 시트는 인간과의 직접 접촉 부위로서 승차감을 평가 할 수 있는 가장 기본적인 항목이다. 따라서 자동차 시트는 승차감과 동시에 충분한 강성과 강도를 가져야 할 것이다. 본 연구에서는 자동차 시트에서의 시트 쿠션 프레임과 백 프레임을 3D 모델링하였고, 쿠션 프레임의 비틀림 강도, 수직하중강도 시험, 백 프레임의 강도 시험 3가지 실험에 대해서 시뮬레이션으로 구조해석을 하였다. 해석결과, 쿠션 프레임 비틀림 강도 시험에서는 초기 전변형량의 최대값은 5.8421mm가 나왔고, 영구 전변형량의 최대값은 0.02539mm가 나왔다. 쿠션 프레임 수직하중강도 시험에서는 쿠션 프레임 앞쪽 끝단의 전변형량은 2.1159mm이고, 뒤쪽 끝단은 0.0606mm이다. 하중을 더 증가한 경우는 전변형량의 최대값은 3.1739mm가 나왔다. 3 가지의 백 프레임 강도 시험에서는 최대의 전변형량은 0.18634mm로 나타났다. 본 연구결과는 자동차 시트 쿠션 프레임 및 백프레임의 과도한 변형 및 파괴가 없음으로서 승객의 안전을 보장하는 충분한 강성과 강도를 검증할 수 있었다.

• 한국지진공학회논문집
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• 제24권1호
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• pp.29-37
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• 2020

This study is to investigate the effect of a retrofitted reinforced concrete frame with non-seismic details strengthened by embedded steel moment frames with an indirect joint, which mitigates the problems of the direct joint method. First, full-scale experiments were conducted to confirm the structural behavior of a 2-story reinforced concrete frame with non-seismic details and strengthened by a steel moment frame with an indirect joint. The reinforced concrete frame with non-seismic details showed a maximum strength of 185 kN at an overall drift ratio of 1.75%. The flexural-shear failure of columns was governed, and shear cracks were concentrated at the beam-column joints. The reinforced concrete frame strengthened by the embedded steel moment frames achieved a maximum strength of 701 kN at an overall drift ratio of 1.5% so that the maximum strength was about 3.8 times that of the specimen with non-seismic details. The failure pattern of the retrofitted specimen was the loss of bond strength between the concrete and the rebars of the columns caused by a prying action of the bottom indirect joint because of lateral force. Furthermore, methods are proposed for calculation of the specified strength of the reinforced concrete frame with non-seismic details and strengthened by the steel moment frame with the indirect joint.

• 한국지진공학회논문집
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• 제17권4호
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• pp.171-180
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• 2013

The purpose of this study is to evaluate the effectiveness of the seismic retrofit performance for a reinforced concrete structure with steel damper. The nonlinear static analysis of the RC frame specimens with and without retrofit using the steel damper was conducted and the reliability of the analysis was verified by comparing the analysis and test results. Using this analysis model and method, additional nonlinear analysis was conducted considering varying stiffness and strength ratios between RC frame and steel damper and the failure mode of RC frame. As the result of the study, the total absorbed energy increased and the damage of RC frame was reduced as stiffness and strength ratios increased. The seismic retrofit performance, evaluated by means of the yield strength, increasing ratio of the absorbed energy and damage of the frame, increased linear proportionally with the increase of the strength ratio. In addition, the seismic retrofit performance was stable for stiffness ratios larger than 4~5. The energy absorption capacity of the frame governed by shear failure was better than that of the frame governed by flexure failure.

• 대한기계학회논문집A
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• 제30권1호
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• pp.97-104
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• 2006

This paper has investigated the strength of the bogie frame for the Korean tilting train that is being developed in KRRI. In this study, the loading conditions imposed on the bogie frame of tilting train were derived and the static and fatigue strength of the bogie frame has been evaluated. In order to achieve these goals, finite element analysis has been performed and the stress concentration areas were investigated. Based on the analytical results, the static load tests were conducted under the nontilting load conditions and the tilting load conditions. The test results were used to evaluate the fatigue strength of the bogie frame by Goodman diagram.

• 한국철도학회논문집
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• 제8권4호
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• pp.321-329
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• 2005

This paper has established the strength evaluation procedure of the bogie frame for the Korean tilting train that is being developed in KRRI, In order to establish the strength evaluation procedure, firstly, the loading conditions imposed on the tilting train were investigated. In addition, the static and fatigue strength of the bogie frame has been evaluated. In order to derive the dynamic loads according to the carbody tilting, the load redistribution effect by carbody tilting, the unbalanced lateral acceleration effect by high-speed curving and the tilting actuator force effect have been considered. Multi-body dynamic analyses have been carried out to evaluate the tilting load cases and the strength analysis has been performed by finite element analyses. From this study, the structural safety of the bogie frame could be ensured.

• Earthquakes and Structures
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• 제9권4호
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• pp.699-718
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• 2015

The effect of reinforcing concrete members with high strength steel bars with yield strength up to 600 MPa on the overall seismic behavior of concrete moment frames was studied experimentally and numerically. Three geometrically identical plane frame models with two bays and two stories, where one frame model was reinforced with hot rolled bars (HRB) with a nominal yield strength of 335 MPa and the other two by high strength steel bars with a nominal yield strength of 600 MPa, were tested under simulated earthquake action considering different axial load ratios to investigate the hysteretic behavior, ductility, strength and stiffness degradation, energy dissipation and plastic deformation characteristics. Test results indicate that utilizing high strength reinforcement can improve the structural resilience, reduce residual deformation and achieve favorable distribution pattern of plastic hinges on beams and columns. The frame models reinforced with normal and high strength steel bars have comparable overall deformation capacity. Compared with the frame model subjected to a low axial load ratio, the ones under a higher axial load ratio exhibit more plump hysteretic loops. The proved reliable finite element analysis software DIANA was used for the numerical simulation of the tests. The analytical results agree well with the experimental results.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.541-548
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• 2006

This study presents a structural cost optimization method for building frame system using high-strength steel members. In, this optimization method, the material cost of steel member is involved in objective function to find the optimal cost of building frame systems. Genetic Algorithm is adopted to optimizer to find structural cost optimization. The proposed adapted to structural design of 3.5 stories example buildings with buildings frame systems. As a result, The proposed optimization method can be effectively adapted to cost optimization of building frame systems using high-strength steel members.