• Steel and Composite Structures
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• v.10 no.4
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• pp.317-329
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• 2010

According to the results of 9 circular concrete filled steel tube (CFT) push-out tests, a new theoretical model for average bond stress versus free end slip curve is proposed. The relationship between verage bond stress and free end slip is obtained considering some varying influential parameters such as slenderness ratio and diameter-to-thickness ratio. Based on measured steel tube strain and relative slip at different longitudinal positions, the distribution of bond stress and relative slip along the length of steel tube is obtained. An equation for predicting the varying bond-slip relationship along longitudinal length and a position function reflecting the variation are proposed. The presented method can be used in the application of finite element method to analyze the behavior of CFT structures.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.105-108
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• 2004

In general, the nonlinear behavior of composite structures composing of steel and concrete is analyzed on the basis of the assumption of the perfect bond actions in steel-concrete interface in which the interface slip or separation is not allowed. The assumption is based on the fact that the full interface bond behavior is provided with the mechanical connectors of studs. However, since the number and spacing of the studs are determined by the stress resultants calculated in the interface area, the interface analysis is required to evaluate the stress resultants. This paper describes the nonlinear steel-concrete interface behavior considering the two interface failure mechanisms of slip and separation. Elastoplastic constitutive relation is developed. thru the formulation framework using the two energy dissipation mechanisms. As the result, the steel plate push-out tests sandwitched between concrete blocks are analyzed and compared with the test results with which the good agreements are observed.

• Journal of Ocean Engineering and Technology
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• v.14 no.2
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• pp.121-127
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• 2000

In this paper a new technique of inverse fairing problem for ship hull is proposed. Recently Lu solved the inverse fairing problem for automobile's body that was made by one surface element. In this system however hull surface is constructed by Gregory's composite surface interpolation method. So reflection line at boundary position is used as a tool of solving inverse problem in surface fairing. But the results are not good. The new concepts of Normal vector line and Constrained reflection line are introduced as an alternative tool. Energy minimization method for Normal Vector Line curve net and the inverse method for Constrained Reflection Line by using optimization technique are examined And the final lines from this proposed surface fairing method shows good fairness.

• Smart Structures and Systems
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• v.20 no.6
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• pp.759-767
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• 2017

Wear and aging associated damage is a severe problem for safety and maintenance of engineering structures. To acquire structural operational state and provide warning about different types of damage, research on damage identification has gained increasing popularity in recent years. Among various damage identification methods, the Lamb wave-based methods have shown promising suitability and potential for damage identification of plate-type structures. In this paper, a comprehensive study was presented to elaborate four remarkable aspects regarding the Lamb wave-based damage identification method for plate-type structures, including wave velocity, signal denoising, image reconstruction, and sensor layout. Conclusions and path forward were summarized and classified serving as a starting point for research and application in this area.

• Proceedings of the KIEE Conference
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• summer
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• pp.1043-1045
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• 2004

This paper deals with the core loss calculation of a BLDC motor made of Soft Magnetic Composite material. Since the teeth of motor partially have overhang in axial direction, 3 - dimensional equivalent magnetic circuit network (3D-EMCN) is used as an analytical method to get flux density of each element. The total core loss is calculated with the magnetic flux density and core loss curves of the SMC material. The calculated result is compared with core loss of the motor without overhang in stator teeth.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.997-1001
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• 2014

In this paper, the interference in small MIMO antennas having two identical composite right- and left-handed transmission-line(CRLH-TL)-based radiating elements is remarkably decreased. The radiating element has the broadside-capacitive coupling as well as slots to be equivalent to the CRLH-TL to prevent the size from increasing for an LTE high band. The suspended line bridging the two radiating elements is optimized to lower the interference between them down to -23 dB, while the overall MIMO antenna system is compact and its antenna performance is acceptable. The design is tested for 2.5 GHz.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.4
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• pp.759-765
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• 2011

This paper proposes an effective assistant model for considering the stator slot-opening effect on air gap flux density distribution in conventional interior-type permanent magnet (IPM) motor. Different from the conventional slot-opening effect analysis in surface-type PM (SPM) motor, a composite effect of slot-opening uniquely existing in IPM motor, which additionally causes enhancement of air gap flux density due to magnet flux path distortion in iron core between the buried PM and rotor surface. This phenomenon is represented by a proposed assistant model, which simply deals with this additional effect by modifying magnetic pole-arc using an effective method. The validity of this proposed analytical model is applied to predict the air gap flux density distribution in an IPM motor model and confirmed by finite element method (FEM).

• KIEAE Journal
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• v.7 no.6
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• pp.119-126
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• 2007

In the field of composite structures, the use of carbon tube for the confinement of concrete has been arisen since 1990's. However, experimental and analytical studies were limited to those of reinforced concrete and concrete filled steel tube. The carbon tube provides excellent confinement capabilities for concrete cores, enhancing compressive strength and ductility of concrete significantly. The carbon tube has high tensile strength, light weight, corrosion immunity and high fatigue strength properties. Since carbon fiber is an anisotropic material, carbon tube could be optimized by adjusting the fiber orientation, thickness and the number of different layers. In this study, both experimental and analytical studies of axial and lateral behavior of full-scale CFCT (Concrete Filled Carbon Tube) columns subjected to monotonic axial load were carried out using Drucker-Prager theory. And, based on comparison results between experiment results and analytical results, k factor estimation was proposed for effective analysis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.323-326
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• 1999

In this paper, a windmill type ultrasonic motor operated by single-Phase AC electric field was fabricated, and then torque characteristics were investigated. A metal-ceramic composite component was used as the stator\`s vibrator to generate ultrasonic vibrations. The windmill type ultrasonic motors has only three components; a stator element with two wind-mill shape slotted metal endcaps, a rotor and a bearing. In this parer we measured torque, when stator\`s slot was changed Iron 4, 6, 8. Brass metal was pressed with umbrella-type using metal molt then slot of 3 kind was manufactured. The maximum revolution speed was 388(rpm) in the case of a small ultrasonic motor of 11.35 mm diameter, 8 slot and 1.01 mm thickness. The maximum torque of 0.17 mNm was obtained at a speed of 131 rpm.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.9
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• pp.938-945
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• 2012

To design and estimate material failures of Type III pressure vessels, which have excellent stability and performance, various modeling techniques have been introduced. This paper provided a hybrid modeling technique composed of ply-based modeling for a cylinder part and laminate-base modeling technique for a dome part for enhancing modeling efficiency. The ply-based modeling technique provided accurate ply stresses directly for predicting material failure, on the other hand, additional manipulations in stress calculations, which may cause some errors, were needed for the case of the laminate-based modeling technique. The ply stresses in fiber, transverse and in-plane shear directions were compared with the corresponding material strengths to predict material failure.