• Journal of Korean Society of Steel Construction
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• v.28 no.4
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• pp.231-242
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• 2016

Earthquake resistance of RC column-steel beam (RCS) joints with simplified details were studied. Simplified details are necessary for large columns to improve the productivity and constructability. To strengthen the beam-column joint, the effects of transverse beams, studs, and U-cross ties were used. Four 2/3 scale interior RCS connections were tested under cyclic lateral loading. The specimens generally exhibited good deformation capacity exceeding 4.0% story drift ratio after yielding of both beam and beam-column joint. Ultimately, the specimens failed by shear mechanism of the joint panel. The test strengths were compared with the predictions of existing design methods.

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.297-304
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• 2003

This paper presents the test results of RCS(Reinforced Concrete Steel) beam-column joint with various types of transverse reinforcements such as small-column-type transverse reinforcements, four-piece ㄱ-shape assembled hoops and four-piece ㄱ-shape welded hoops. Five interior beam-column joint specimens were tested to examine the seismic performance and the shear strengths. From the test results, it was found that all the specimens sustained their strength at large levels of story drift(${\theta}$=0.035) without significant loss of strength and stiffness. Therefore it was concluded that the seismic performance and shear strength of the proposed RCS joint are at least the same as those of the specimen with conventional reinforcing details. Also, the contribution of the outer panel to the shear strength of the joint should be evaluated by the compression strut mechanism rather than compression field mechanism.

• Journal of Korean Society of Steel Construction
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• v.21 no.6
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• pp.647-657
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• 2009

This paper studies the behavior of joints in steel-PSC (prestressed concrete) hybrid beams, which is necessary for the application of hybrid beams to spliced girder bridges, and proposes a new type of joint with improved construction convenience and structural behavior. In the proposed joint, perfobond rib shear connectors are attached to the upper and lower plates, which are expanded from the steel girders and located between the steel girder and the PSC girder. The experimental tests were performed on hybrid beams with the suggested joint. The results showed that all the beams had similar ultimate strengths and failure modes, due to the failure of their PSC parts. The composite action of the perfobond ribs was verified by examining the initial stiffness and cracks of the test beams. In addition, the test beams showed a higher degree of ultimate strength than the beams with stud shear connectors in the joints that had been previously studied. Thus, the proposed joint is effective for the steel-PSC hybrid beam.

• Journal of Technologic Dentistry
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• v.36 no.4
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• pp.239-246
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• 2014

Purpose: The purpose of this study was to compare the tensile strength and mechanical properties of orthodontic wire joints made by gas soldering and laser welding, with and without filling material, to identify the effectiveness and potential clinical application of laser welded orthodontic wires. Methods: Three joint configurations of orthodontic wire were used: diameter 0.9 to 0.9 mm wire, diameter 0.9 to 0.5 wire and diameter 0.9 mm wire to band. The joints were made using three different methods: gas soldering, laser welding with and without filling material. For each kind of joint configuration or connecting method 7 specimens were carefully produced. The tensile strengths were measured with a universal testing machine (Zwick/Roell, Instron, USA). The hardness measurements were carried out with a hardness tester(Future-Tech Co. Tokyo, Japan). Data were analyzed by AVOVA(p= .05) and Turkey HD test(p= .05). Results: In all cases, gas soldering joints were ruptured on a low level on tensile bonding strength. Significant differences between laser welding and gas soldering(p< .05) were found in each joint configuration. The highest tensile strength means were observed for laser welding, with filling material, of 0.9 to 0.9 mm wire joint. Conclusion: In conclusion, the elastic modulus and tensile strength means of laser soldering with filling material were the highest, and the tensile strength means of laser soldering were higher than those of gas soldering.

• Journal of the Korean Wood Science and Technology
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• v.38 no.3
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• pp.199-204
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• 2010

Members used for the Korean traditional joints have been processed by handicraft, especially with domestic red pine species. Dovetail joint is most commonly used in woodworking joinery and traditional horizontal and vertical connections. It is able to be processed much easier to cut by handicraft and machines. However, although it is processed straight forwards, it requires a high degree of accuracy to ensure a snug fit. Also, tenons and mortises must fit together with no gap between them so that the joint interlocks tightly. A few scientific studies on the dovetail joints have been conducted so far. For the effective applications of traditional joints and domestic plantation wood species, dovetail joints were assembled by larch glulam members processed by machine pre-cut. To identify the tensile properties of through dovetail joints, larch glulam with 150 150mm in cross section were prepared. Furthermore, various geometric parameters of dovetai joints such as width, length, and tenon angle, were surveyed. The ends in the mortise was cracked mainly at a low strength level in the control specimens without reinforcements. The maximum tensile strengths of reinforced specimens considering real connections such as capital joint and headpiece on a column, increasedby handicraft, especially with domestic red pine species. Dovetail joint is most commonly used in woodworking joinery and traditional horizontal and vertical connections. It is able to be processed much easier to cut by handicraft and machines. However, although it is processed straight forwards, it requires a high degree of accuracy to ensure a snug fit. Also, tenons and mortises must fit together with no gap between them so that the joint interlocks tightly. A few scientific studies on the dovetail joints have been conducted so far. For the effective applications of traditional joints and domestic plantation wood species, dovetail joints were assembled by larch glulam members processed by machine pre-cut. To identify the tensile properties of through dovetail joints, larch glulam with 150 150mm in cross section were prepared. Furthermore, various geometric parameters of dovetai joints such as width, length, and tenon angle, were surveyed. The ends in the mortise was cracked mainly at a low strength level in the control specimens without reinforcements. The maximum tensile strengths of reinforced specimens considering real connections such as capital joint and headpiece on a column, increased by two times with shear failures on the tenon than the control specimens. The maximum tensile strength was obtained in the specimen of 25 degrees, and no difference was observed in the changes of neck widths.

• Composites Research
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• v.31 no.6
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• pp.323-331
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• 2018

The effect of stainless steel jagged-pin reinforcement on the pull-off strength of the composite hat-joint was studied by the test. The pins were physically and chemically surface-treated and inserted in the thickness direction over the interface where the skin and stiffener meet. The specimens including the jagged-pins were made by co-curing process. Diameters of the jagged-pins were 0.3, 0.5 and 0.7 mm. The pin areal densities were set to 0.5 and 2.0% based on the interface area where the skin and stiffener meet. The specimens using 0.3 mm diameter normal (un-jagged) pins with 2.0% areal density were additionally fabricated and tested to investigate the pin shape effect on the pull-off strength. The pull-off strengths of specimens reinforced with 0.5% areal density by 0.3, 0.5, and 0.7 mm diameter pins were 45, 19 and 9% higher than those of un-reinforced specimens, respectively. In case with 2.0% pin areal density, the strengths were 127, 45, and 11% higher than those of un-reinforced specimens, respectively. The test results show that the higher pin areal density results in the higher strength when the pin diameter is the same. When the pin areal density is the same, the smaller pin diameter leads to higher strength. When the joints using jagged-pins and normal pins in 2.0% areal density with 0.3 mm diameter, the joints of jagged-pins showed the 64% higher strength. From the results of this study, it was confirmed that jagged-pin reinforcement can be an effective method for improving the pull-off strength of composite hat-joint.

• Journal of Welding and Joining
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• v.21 no.7
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• pp.59-64
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• 2003

Microstructure and shear strength of Sn-Zn lead-free solders and Au/Ni/Cu UBM joint under thermal aging conditions was investigated. The samples were aged isothermally at 10$0^{\circ}C$ and 15$0^{\circ}C$ for 300, 600, and 900 hours. The IMCs(Intermetallic Compound) at the interface between solder and UBM were examined by FESEM and TEM. The results showed that the shear strength was decreased with aging time and temperature. The solder ball with high activated RA flux had about 8.2% higher shear strength than that of RMA flux. Poor wetting and many voids were observed in the fractured solder joint with of RMA flux. The decreased shear strengths were caused by IMC growth and Zn grain coarsening. Zn reacted with Au and then was transformed to the $\beta$ -AuZn compound. Although AuZn grew first, $r-Ni_5Zn_{21}$ compounds were formed with aging time. The layers indicated by $Ni_5Zn_{21}(1)$, (2), and (3) were formed with the thickness of ∼0.7 ${\mu}{\textrm}{m}$, ∼4 ${\mu}{\textrm}{m}$, and ∼2 ${\mu}{\textrm}{m}$, respectively.

• Journal of Welding and Joining
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• v.18 no.3
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• pp.106-113
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• 2000

Single crystallization behavior ad high temperature tensile properties of TLP bonded joints of Ni-base single crystal superalloy, CMSX-2 were investigated using MBF-80 and F-24 insert metals. CMSX-2 was bonded at 1523~1548K for 1.5~1.8ks in vacuum. The (100) orientation of bonded specimen was aligned perpendicular to the joint interface. Crystallographic orientation analyzed points over the bonded region possessed the almost same orientation across the joint interface and misorientation $\Delta^{\theta}$ was negligibly small in as-bonded and post-bond heat-treated situations. It was confirmed that single crystallization could be readily achieved during TLP bonding. The tensile strengths of all joints at elevated temperatures were equal to or greater than those of base metal the range of testing temperature between 923K and 1173K. The elongation and reduction of area in values were almost the same as those of base metal. SEM observation of the fracture surfaces of joints after tensile test revealed that the fracture surface indicated the similar morphologies each other, and that the fracture of joints occurred in the base metal in any cases.

• Journal of muscle and joint health
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• v.27 no.2
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• pp.81-93
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• 2020

Purpose: We developed and tested the effects of a care program for dementia patients among community- dwelling older adult men. Methods: This study used a non-equivalent control group pre-and post-test design. To verify the effectiveness of the care program for dementia patients, 26 community dwelling older adult men participated in this study. We used multiple intervention strategies including improving understanding of dementia through education, activities for dementia prevention, and promoting psychological change. In particular, based on the current understanding of the care of the men older adults, we used strategies to promote motivation and reinforce strengths. Results: After completing the 6-week intervention program, when compared with the control group, older adult men in the care program intervention group showed significant differences in scores for the following: cognitive functions (p=.035), attitude toward dementia (p=.026), preventive behavior (p=.007), geriatric depression (p=.013), caring confidence (p=.018), and self-esteem (p=.013). Conclusion: These results indicate that the care program for dementia patients has positive effects on increasing their cognitive function, attitude toward dementia, preventive behavior, caring confidence, self-efficacy, and on decreasing depression rates in this population. Based on this, we can recommend this program to men caregivers for the improved care of dementia in community centers.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.747-754
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• 1988

High strength steels (HS) of dual phase and monogalvanized steel sheets (GA ; plated plane, GAB ; bare plane0 were used to investigate the fatigue strengths of four kinds of single-spot-welded joint specimen under tensile-shear repeated load. The specimen is classified as the same mating metal specimen (HS*HS, GA*GAB) and different mating metal specimen (HS*GA, HS*GAB). Some of the results are ; (1) Static tensile load of single-spot-welded joint specimens is proportional to tensile strength of metal and rigidity of mating metal sheet. (2) Fatigue life of HS*HS specimens increased about 20% longer than that of GA*GAB specimens in low cycle range. (3) In different mating metal specimens, the fatigue life of HS*GA specimens increased about 84% more that of HS*HS specimens in high cycle range.