• Proceedings of the Korean Vacuum Society Conference
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• 1997.07a
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• pp.169-172
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• 1997

MgO dielectric pprotection layer is ppreppared by R.F. reactive magnetron spputtering with Mg target under various conditions of spputtering ppressure, time and substrate tempperature. Discharge characteristics of ppDpp is also studied as a pparameter of MgO pprepparation conditions. As the working ppressure and substrate tempperature was increase, the discharge voltage was decreased. Two kinds of MgO ppreppared both spputtering and E-beam methods were stable after annealing at 35$0^{\circ}C$ for 120min. discharge voltage under 3 mixed gas(He+Xe0.2%+Ne30%) was V=130V, V=102V and ${\gamma}$ coefficient was twiced as much as that of dielectric layer.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.243-246
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• 1994

In this paper, a self-learning fuzzy controller is designed with a fuzzy approximation of an inverse model. The aim of an identification is to find an input command which is control of a system output. It is intuitional and easy to use a classical adaptive inverse modeling method for the identification, but it is difficult and complex to implement it. This problem can be solved with a fuzzy approximation of an inverse modeling. The fuzzy logic effectively represents the complex phenomena of the real world. Also fuzzy system could be represented by the neural network that is useful for a learning structure. The rule of a fuzzy inverse model is modified by the gradient descent method. The goal is to be obtained that makes the design of fuzzy controller less complex, and then this self-learning fuzz controller can be used for nonlinear dynamic system. We have applied this scheme to a nonlinear Ball and Beam system.

• Steel and Composite Structures
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• v.2 no.5
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• pp.397-410
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• 2002

The main aim of the present paper is to present the results of a full-scale experimental investigation to study the structural behaviour of composite steel beams. The composite beam was made of cold-formed steel section shapes filled with reinforced concrete. First a comprehensive description of the experimental results in terms of: deflections, deformations, slippage and stress levels on critical steps of the load path is presented. The experimental results were then compared to theoretical values obtained by the use of an analytical model based on ultimate limit state stress blocks. Finally, a practical application of the use of this structural solution is depicted.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.553-558
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• 1999

As a process of development of composite beam-column connection system, structural tests have been conducted to verify moment resisting performance of the system. The tests have been proceeded by two steps, the first being welding performance test of the steel connection rod and stiffners, and the second overall moment resisting capacity of the fuly assembled system. Ten welding test specimens and four prototype specimens have been used in the test. Good structural performance of welding test specimens has been observed without any single welding failure, and sufficient moment resisting capacity has been proved from the overall performance test, with the moment magnitude in excess of the calculated plastic moment.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.247-250
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• 2005

The aim of this study was to examine the emission of acoustic signals from three reinforced concrete beams at cracking and failure processes. Acoustic emission(AE) characteristics of reinforced concrete beams were investigated during the entire loading period. AE technique was used to evaluate the characteristics of damage process and the failure mechanism of reinforced concrete beam with natural and recycled aggregates. The influences of different aggregate in concrete on AE characteristics were investigated as well.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.198-201
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• 2003

The R.C Building will be superannuated as time passes. This program is generated by propagation of cracks. In order to manage such cracks, time and efforts, expense, etc. are required. In this study, glass sensors were embedding in a model beam and column and leakage of fluorescence and adhesive material was investigated. Further, currents in glass pipe were observed to find the leakage of liquid in glass pipes. Progressive cracks generated by cause the fracture of glass pipes. Therefore, the liquid become to flow and electric current stops, and the cracked part of the member can be found easily. Moreover, the adhesive delays progressive cracking system that responds in air, and the life of a structure can be made to extend. The purpose of this research is to develop of low price sensors that can perform of self-diagnosis in addition to ability of concrete repair concrete to damage.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.184-189
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• 1993

This is an experimental investigation the shear behavior of reinforced concrete with stirrup of which stress ranges 0.0㎏/㎠ to 7.0㎏/㎠. Five rectangular beams which concrete strengths are 287㎏/㎠ and 380㎏/㎠, a/d=3, and main steel ratio equal to 1.96% was tested. Those were designed to fail in shear. The shear cracking load and failure load were measured and compared with ACI's equation and Zutty's proposed equation. The results are following : ACI equation and Zutty's equation are consertive. As the concrete compressive strength increased, reserved shear strength of beams with minimum web reinforcement decreases. According to increase of web reinforcement , the rate of increases of shear strength is decreased. The failure modes of specimen with minimum web reinforcement are shear compression failure which is reached after diagonal shear cracking.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.208-211
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• 2002

In RC beams strengthened with Epoxy-Bonded Fiber, debonding failure happens frequently. Moreover, through the life cycle, it is difficult to recognize clacks and deflections on the surface of concrete members strengthened with Epoxy- Bonded Fiber. For these reasons, we must always monitor the state of RC beams. The Optical FBG sensor is broadly accepted as a structural health monitoring device. The main objective of this paper is that it's possible to monitoring the debonding failure of R.C. beams strengthened with Epoxy-Bonded Fiber. For that, we fixed two Optical FBG sensors at the center of the beam and another two sensors in the end of Epoxy-Bonded Fiber, According to the comparison micro-strain between embeded sensor in concrete and that on the fiber surface, we can find the point which debonding failure occurs

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.145-152
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• 2005

This paper presents a deformable strut-and-tie model of determining the shear strengths and ultimate deformations of the shear-dominant reinforced concrete members. The proposed model originates from the strut-and-tie model concept and satisfies equilibrium, compatibility, constitutive laws, and the geometric conditions of shear deformation. This study attempts to apply deformation patterns to strut-and-tie models. The yielding of flexural reinforcements determines yielding states and the ultimate states of reinforced concrete coupling beam are defined as the ultimate compressive strain of struts and the degradation of compressive strength due to principal tensile strain of struts. The validity and accuracy of the proposed model is then tested against available experimental data. The parameters reviewed include the ratios of truss action and arch action, the reinforcement ratios, and the shear span-depth ratio. It is expected that this model can be applied to displacement-based design methods.

• Progress in Superconductivity
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• v.12 no.1
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• pp.17-22
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• 2010

Distribution of local critical temperature and current density in $YBa_2Cu_3O_{7-\delta}$ (YBCO) coated conductors was analyzed using a Low-temperature Scanning Laser Microscopy (LTSLM). We prepared YBCO coated conductors of various bridge types to study the spatial distribution of critical temperature and current density in single and multi bridges. An LTSLM system was modified for a detailed two-dimensional scan without shifting of the sample. We observed a spatial distribution of the critical temperature from the bolometric response, which arises from a focused laser beam at the sample near the superconducting transition. Also we studied the relation between the critical temperature and the current density.