• The Journal of Korean Academy of Prosthodontics
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• v.29 no.3
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• pp.101-110
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• 1991

The purpose of this study was to compare the repaired joint strength among several edge profiles after denture repair. For this study, eight edge profiles were used for repair methods and five self-curing resin brands were used for repair materials. Break away loads were tested after 1 hr., 24 hrs. and 1 week. Instron was used for testing the transverse strength of repaired specimen. The results were as follows. 1. Repaired joint strength was about 35-65% of that of original specimen. 2. Joint strengths of round, inverse knife, inverse rabbit, lap ogee joint were higher tnan that of traditional simple butt joint 3. Joint strength of the simple butt joint was low significant. 4. Joint strengths after 1 hr. specimen were lower than those of 24 hrs. and 1 week specimens in joint strengths. 5. There were no significant differences between 24 hrs. and 1 week specimens in joint strengths. 6. It look more than 24 hours to gain satisfactory physical property after repairing the fractured denture base when self-curing resin was used for repair.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.2
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• pp.154-158
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• 2013

Expansion joint has been utilized in many areas including automotive bellows for exhaust system. Usage of expansion joint has been increased due to its inherent flexibility and excellent anti-vibration property. Simple shape of expansion joint is modeled to understand the behavior of joint system. 27 design cases using 3 design factors with 3 levels are constructed by design of experiment. Each case is simulated to find the most influential design factors. Response for this study, maximum stress in the expansion joint, has been used to determine main design factors of joint. Among the 3 design factors, factor B has affected greatly a response in the formation of optimum shape of joint. Also, interaction factor, $A{\times}B$, has also showed its influence to the response of joint. This study showed that design of experiment combined with finite element analysis could be used in the design decision process effectively in the design of expansion joint.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.2
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• pp.49-55
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• 2011

The failure of electronic instruments is mostly caused by heat and shock. This shock causes the crack initiation at the solder joint interface of PCB component which is closely related with the formation of intermetallic compound(IMC). The Ag content in Pb-free Sn-xAg-0.5Cu solder alloy used in this study was 1.0, 1.2 and 3.0 wt.%, respectively. After soldering with PCB component, isothermal aging was performed to 1000 hrs. The growth of IMC layer was observed during isothermal aging. The drop impact property of solder joint was evaluated by impact bending test method. The solder joint made with the solder containing lower Ag content showed better impact bending property compared with that with higher Ag content. On the contrary to this result, the solder joint made with solder containing higher Ag content showed better impact bending property after aging. It should be caused by the formation of fine $Ag_3Sn$, which relieved the impact. It showed consequently the different effect of fine $Ag_3Sn$ and coarse $Cu_6Sn_5$ particles formed in the IMC layer on the impact bending property.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.285-286
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• 2008

In practical applications of HTS tapes for electric devices such as coils and power cables, the jointing of HTS tapes is needed. In magnet applications superconducting joints are needed to achieve very low resistance at the joint, but for power device applications, a slightly higher joint resistance may be acceptable. In this study, an economical joint with good mechanical and electrical integrity could be achieved for Bi-2223 tapes which can be applicable to electric power applications. A lap joint method has been used. The joint resistance and strength of the jointed Bi2223 tapes have been evaluated. Electro-mechanical properties of the joint sample under tension have been examined and compared with the case of the single tapes.

• Structural Engineering and Mechanics
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• v.87 no.4
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• pp.391-403
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• 2023

In this study, a new type of self-centering beam-column joint with tapered steel plate links is proposed. Firstly, mechanical property of the basic joint (with the prestressed steel strands only, to provide the self-centering ability) and the combined joint (with both the prestressed steel strands and tapered steel plate links, to provide self-centering and energy dissipation simultaneously) is theoretically analyzed. Then, three joints with different dimensions and combinations of tapered plate links are designed and tested through a series of quasi-static cyclic loading tests. Test results show that a nearly bilinear elastic moment-rotation relationship for the basic joint is obtained. With the addition of tapered steel plate links, typical flag-shape hysteretic curves are obtained, which indicates good self-centering and energy dissipating ability of the combined joint. By installing multiple tapered plate links, stiffness and bearing capacity of the beam-column joint can be enhanced. The theoretical moment-rotation relationships agree well with the test results. A simplified macro model of the proposed joint is developed using OpenSees, which simulates reasonably well its hysteretic behavior.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.2
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• pp.385-392
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• 1993

This paper presents a new stable composite control law for the flexible joint robot manipulators, which incorporate an additional stabilizing control law with the sliding property. The singularly perturbated models in this paper include inertia moments which are functions or the deformations of actuators as well as link positions. The values of renewedly defined fast controller variables are computer from the corrected reduced-order model without additional computational loads. Proposed schemes are compared with the conventional one. The simulations for 2 DOF flexible joint manipulator show that the proposed schemes are more stable than the conventional scheme, and especially effective for the manipulator with high joint-flexibilities.

• Special Issue of the Society of Naval Architects of Korea
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• 2017.10a
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• pp.8-13
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• 2017

The rolled carbon steel plate has anisotropic property in Z-direction(thickness direction). This is induced by cooling rate difference of Z-direction and sulfur which make non-metallic inclusion(MnS) at center line of thickness direction. Z-directional mechanical properties of normal steel plate are not generally specified and it is defined for Z-Quality steel only through tensile test in Z-direction. If Z-quality steel is not applied for cruciform joint, the lamella tearing will be occurred by tensile stress after welding & during operation of the structure. In this research, one equation estimating Z-directional(orthogonal to plate) stress was developed to prevent lamella tearing by welding. This equation deals with plate thickness & joint configuration(eccentricity, angle and curvature). Analyses were done by strain boundary method using sectional FE modeling and FE 3D models are also used for some cases. Designers can predict the possibility of lamella tearing by adequately applying the result and can appropriately minimize the application of Z-quality steel by revising welding design to some extent.

• Journal of The Geomorphological Association of Korea
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• v.23 no.1
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• pp.1-16
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• 2016

This study estimates relationships between physical and chemical weathering indices of various rock types and topographical relief. Physical weathering properties such as rock strength and joint and chemical weathering indices such as the $SiO_2/Al2O_3$, CIA and WPI were analyzed from 18 rock outcrops in mountain and valley areas consisting of 9 rock types. The results indicate that the elevation and relief of topography increase physical strength of rock increases. It can be suggested that the total r(rock-mass strength rating) and R(rock rebound strength by Schmidt Hammer) are most useful indices as a quantitative weathering property factor to explain formative causes of topographical relief. The results also suggest that rock types such as sandstone, granite, gneiss and schist are most suitable to explain meaningful difference in topographical relief with the physical and chemical weathering indices.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1635-1642
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• 2012

The identification of the dynamic properties of structural joints is important for predicting the dynamic behavior of assembled systems. However, the identification of the properties using analytical or experimental approaches is extremely difficult or even impossible. Several studies have proposed hybrid or synthesis methods that simultaneously used analytical and experimental approaches to identify the dynamic properties of a joint. However, among the many types of joints, only the bolt joint was treated as a practical example in these studies. In this study, for a simple assembly system comprising two plates and one hinge joint, a simple methodology involving the use of the static-based subpart analysis method to identify the dynamic properties is proposed. Finally, the proposed method is applied to a glove box in a passenger vehicle that includes hinge joints.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.1
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• pp.41-48
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• 2013

Several fatigue damages have recently been reported which cannot be resolved in the context of the existing fatigue design procedure, and they are suspected to be the cracks induced by the low cycle fatigue mechanism. To tackle the problem, a series of material tests together with fatigue tests have been carried out, and elasto-plastic notch strain analysis using nonlinear kinematic hardening model has been performed. The cyclic stress-strain curves are obtained and the nonlinear kinematic hardening model was calibrated based on the obtained material data. Also, the fatigue test with non-load-carrying cruciform fillet welded joint has been performed in low cycle fatigue regime. Then, the notch strain analyses have been carried out to find the precise elasto-plastic behavior of the material at the notch root of the cruciform joint. The variation of the material property from the base metal via HAZ up to the weld metal was taken into account using spatial variation of the material property. Then the detail elasto-plastic behavior of the welded joint subjected to the repeated cyclic loading has been investigated further through the comparison with the prediction with Neuber's rule. The calibration of the nonlinear kinematic hardening model and nonlinear notch strain analyses have been performed using the commercial FE program ABAQUS.