• 한국소음진동공학회논문집
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• 제11권8호
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• pp.303-313
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• 2001

The identification of power flow in dynamically loaded structures Is essential in the analysis of structure-borne noise. However there are no general purpose tools to estimate powers flow. To make matters worse. It is very difficult to measure it. The power flow can be formulated in terms of balance forces(ELFORCE) at each element and velocities at the associated node obtained with MSC/NASTHAN. In this paper the procedure which is consist of the computations of the balance forces of al1 elements and the velocities at all nodes using MSC/NASTRAN. The calculations of the power f1ow at each element using PCL(PATRAN Command Language) and the Preparation of post -processes is set UP.

• 한국자동차공학회논문집
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• 제6권5호
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• pp.146-152
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• 1998

Recently, for the development of vehicle structures and components there is a tendency to increase using numerical simulation methods compared with practical tests for the estimation of the fatigue strength. In this study, an integrated powerful methodology is suggested for fatigue strength evaluation through development of the interface program to integrate dynamic analysis quasi-static stress analysis and fatigue analysis, which were so far used independently. To verify the presented evaluation method, a single and zigzag bump run test, 4-post road load simulation and driving durability test have been performed. The prediction results show a good agreement between analysis and test. This research indicates that the integrated life prediction methodology can be used as a reliable design tool in the pre-prototype and prototype development stage, to reduce the expense and time of design iteration.

• 한국정밀공학회지
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• 제24권12호
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• pp.128-135
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• 2007

Micro-channels for a wave micropump have been fabricated using the Stereolithography and UV Photolithography. The micro-channel with a channel height of $500\;{\mu}m$ was fabricated with stereolithography. UV photolithography was used for producing micro-channels with a channel length less than $100\;{\mu}m$. The fabrication process data including spinning rpm, pre-bake and post-bake time, and develop time for single layer and multiple layer 3D micro-structures using SU-8 photo resist are experimentally found. A film mask printed with a 40,000 dpi laser printer was used for UV lithography and micro-structures in the order of tens of micrometers in dimension were successfully fabricated.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.965-970
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• 2002

The strengthening of concrete structures in situ with externally bonded carbon fiber is increasingly being used for repair and rehabilitation of existing structures. Carbon fiber is attractive for this application due to its good tensile strength, resistances to corrosion, and low weight. Generally bond strength and behavior between concrete and carbon fiber mesh(CFM) is very important, because of the enhanced bond of CFM. Therefore if bond strength is sufficient, it will be expected to enhance reinforcement effect. If insufficient, reinforcement effect can not be enhanced because of bond failure between concrete and CFM. This study is to investigate the bond strength of CFM to the concrete using direct pull-out test and tensile-shear test. The key variables of the experiment are the location of clip, number of clips and thickness of cover mortar. The general results indicate that the clip anchorage technique for increasing bond strength with CFM appear to be effective to maintain the good post-failure behavior.

• Computers and Concrete
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• 제9권5호
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• pp.357-374
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• 2012

The aim of this paper is to develop a procedure able to calculate the long-term stress and strain patterns in modern prestressed composite structures which are largely influenced by creep and shrinkage and whose final static configuration is the result of many phases of loading and restraints conditions. The introduction of equivalent moduli, depending on the viscous and elastic features of materials, can guarantee a significant simplification of the problem presented above. The proposed calculation model has been used to design the "Quattroquercie Viaduct" located on the highway "A3" Salerno-Reggio Calabria, Italy.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1996년도 가을 학술발표회 논문집
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• pp.210-217
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• 1996

Under strong shock loads including earthquake or blast, structures may start to crack in stress concentrated members. The continuous behavior of the structure changes to the discontinuous. In this study, numerical method analyzing continuous and discontinuous behavior of a structure is developed using a modified distinct element method. Equations of motion of each distinct element are integrated using the central difference method, one of the finite difference methods. Interactions between he elements are considered by an element and pore spring. The forces acting in the center of an element include contact stress transferred by element spring; tensile stress by pore spring; and external traction such as earthquake or blast load. To verify the proposed method, the behavior of the cantilever beam subject to the quasi-static concentrated force at the end is investigated. The failure behavior of the simply supported beam subject to the strong shock at the center is studied. The proposed method can predict the failure behavior of the structure due to the shock loading and the post-failure discontinuous behavior of the structure.

• International Journal of Concrete Structures and Materials
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• 제10권1호
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• pp.99-112
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• 2016

During earthquake, reinforced concrete walls show complicated post-yield behavior varying with shear span-to-depth ratio, re-bar detail, and loading condition. In the present study, a macro-model for the nonlinear analysis of multi-story wall structures was developed. To conveniently describe the coupled flexure-compression and shear responses, a reinforced concrete wall was idealized with longitudinal and diagonal uniaxial elements. Simplified cyclic material models were used to describe the cyclic behavior of concrete and re-bars. For verification, the proposed method was applied to various existing test specimens of isolated and coupled walls. The results showed that the predictions agreed well with the test results including the load-carrying capacity, deformation capacity, and failure mode. Further the proposed model was applied to an existing wall structure tested on a shaking table. Three-dimensional nonlinear time history analyses using the proposed model were performed for the test specimen. The time history responses of the proposed method agreed with the test results including the lateral displacements and base shear.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.83-87
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• 2004

In this work, the cure cycle of co-cured metal/composite structure was investigated to decrease fabricating thermal residual stresses between the metal and the composite material. DSC (Differential scanning calorimetry) experiment and static lap shear test of co-cured aluminum/composite double lap joint as well as the curvature experiment of co-cured steel/composite strip were performed to investigate the effect of curing cycle on the thermal residual stress of co-cured hybrid structures. From the experiments, it was found that post curing method after abrupt cooling of co-cured aluminum/composite hybrid structure at certain point of degree of cure during curing process could eliminate fabricating the thermal residual stresses.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.421-426
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• 2005

In general, structural integrity of rolling stock structures should last more than 25 years. During the lifetime corrosive degradation occurs. For structural design and diagnosis, quantitative relationship between corrosive degradation and variation of mechanical properties such as tensile strength and fatigue strength is needed. In this study, first of all we established the atmospheric corrosion test procedure. At regular intervals using specimens of SM490A and SS400 on the atmospheric corrosion test bed, we carried out tensile and fatigue tests. The fatigue strength decreases as the atmospheric corrosion period increases. And we studied the effect of post-weld heat treatment on the tensile and fatigue behaviour.

• 펄프종이기술
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• 제34권2호
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• pp.67-72
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• 2002

The two stage laccase-assisted delignification process led to significant lignin removal in the non-pressurized treatments. It is clearly shown that an alkaline extraction prior to the second laccase treatment significantly increased the overall delignification by ∼15%. This is in line with the contention that the residual lignin has undergone structural changes during the alkaline extraction, and the resulting modified structures are susceptible to the laccase oxidation. In phenolic hydroxyl group, the pre- methylated sample was very responsive to the delignification process. The phenolic hydroxyl groups could be increased during side chain cleavage catalyzed by laccase. This finding demonstrates that the delignification oi etherified structures is an important reaction in the delignificaton by laccase.