• International journal of advanced smart convergence
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• v.4 no.1
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• pp.145-153
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• 2015

Friction Stir Welding (FSW) is a solid state welding that could successfully weld the difficult-to-weldmaterials such as an aluminum alloy. In this welding process, the stirrer of the welding tool is one of the important factors for producing the perfect sound joint that indicates the higher joint strength. So, this report aims to apply the friction stir welding using various stirrer geometries to weld the AA6063-T1 aluminum alloy butt joint, investigates the mechanical properties of the joint and then compares the mechanical properties with the microstructure of the joint. An experiment was started by applying the friction stir welding process to weld a 6.3 mm thickness of AA6063-T1 aluminum alloy butt joint. A study of the stirrer geometries effect such as a cylindrical geometry, a cone geometry, a left screw geometry and a right screw geometry at a rotational speed of 2000 rpm and a welding speed of 50-200 mm/min was performed. The mechanical properties such as a tensile strength and a hardness of the joint were also investigated and compared with the microstructure of the joint. The results are as follows. A variation of FSW Stirrer shape directly affected the quality AA6063-T1 aluminum alloy butt joint. A cylindrical stirrer shape and a cone stirrer shape produced the void defect at the bottom part of the weld metal and initiated the failure of the joint when the joint was subjected to the load during the tensile test. Left and right screw stirrer shapes gave the sound joint with no void defect in the weld metal and affected to increase the joint strength that was higher than that of the aluminum base metal.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.53-62
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• 2004

A single layer latticed dome is one of the most efficient structures because of its low specivic gravity. For easily analyzing of a single layer latticed dome, joint system is assumed to be pin or rigid joint. However, its joint uses ball whose system has intermediate properties of pin and rigid joint. Therefore this study has a grasp of bending rigidity, stress and mechanical properties through experimental and analyzing method of the bolt inserted ball joint. To analyze the stress of bolt and sleeve, this study uses through 3D elastic contact and cubic element, and then the ball and the bolt are perfectly connected for easily analyzing Compared experimental results to F.E.M, each specimen has an error of less than 12 percent. In the results of stress distribution through F.E.M, stress occurs from bottom of bolt to top of sleeve, and most of tension appears on the bolt, also compression occurs from upper parts of the bolt to the sleeve. The assumption of bending stiffness in ball joint is well known that bolt resists only tension and upper sleeve resiss compression. The results of experiment and analysis have $7{\sim}56%$ error, assuring that upper part of bolt occurs of partial compression. In the result of modified assumption have $4{\sim}20%$ error.

• International Journal of Automotive Technology
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• v.8 no.6
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• pp.723-730
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• 2007

The typical design of automotive driveshafts generally utilizes Constant Velocity(CV) joints as a solution to NVH. CV joints are an integral part of vehicles and significantly affect steering, suspension, and vehicle vibration comfort levels. Thus, CV joints have been favored over universal joints due to the constant velocity torque transfer and plunging capability. Although CV joints are common in vehicle applications, current research works on modeling CV joint friction and assumes constant empirical friction coefficient values. However, such models are long known to be inaccurate, especially under dynamic conditions, which is the case for CV joints. In this paper, an instrumented advanced CV joint friction apparatus was developed to measure the internal friction behavior of CV joints using actual tripod-type joint assemblies. The setup is capable of measuring key performance of friction under different realistic operating conditions of oscillatory speeds, torque and joint installation angles. The apparatus incorporates a custom-installed triaxial force sensor inside of the joint to measure the internal CV joint forces(including friction). Using the designed test setup, the intrinsic interfacial parameters of CV joints were investigated in order to understand their contact and friction mechanisms. The results provide a better understanding of CV joint friction characteristics in developing improved automotive driveshafts.

• Progress in Superconductivity and Cryogenics
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• v.16 no.1
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• pp.32-35
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• 2014

Recently, many researches on the system of superconducting power supply and superconducting magnetic energy storage (SMES) using high temperature superconducting (HTS) tapes has been progressed. Those kinds of superconducting devices use the heater trigger switches that have a control delay problem at moments of heating up and cooling down. One way to reduce the time delay is using a different HTS tape at trigger part. For example, HTS tape having lower critical temperature can reduce time delay of heating up and heating down stage for heater trigger operation. This paper deals with resistances joint with different kinds of HTS tapes which have different properties to verify usefulness of the suggested method. Three kinds of commercial HTS tapes with different specifications are selected as samples and two kinds of solders are used for comparison. Joint is performed with temperature and pressure controllable joint machine and the joint characteristics are analyzed under the repeatable conditions.

• Journal of Korean Society of Steel Construction
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• v.12 no.5 s.48
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• pp.537-547
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• 2000

The tube flange joint often used in the field is a kind of tensional joint method using the high strength bolts. Transferring stress is conducted by high axial pressure between each part of material that is produced by twisting the high strength bolts. And historical characteristics of the flange joint have not been studied sufficiently and it is difficult to say that the design method is established definitely. Therefore new method using ultimate strength is need to be suggested to solve there problems in using flange joint. The purposes in this study are to gain the data base for establishing design method of joint in the form like figure1 and survey whether the joint of tube flange with non-equal diameter can be designed or not in the form like rib or ring.

• Journal of the Korea Convergence Society
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• v.5 no.2
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• pp.7-11
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• 2014

The artificial joint is consisted with the upper structure of tungsten alloy steel and the lower part of polyethelene are applied with load. When this joint is applied with load in this study, the load distribution at the joint and the stress distribution of support hole to install the joint are investigated by finite element analysis. These results can be utilized at obtaining the basic material to have the experiment for the real thing. The crack is initiated as the load is concentrated at the end of corner on the upper structure. This behavior is in accord with a case of tissue damage due to the breakage of artificial joint reported at medical science.

• Journal of architectural history
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• v.16 no.1
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• pp.83-99
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• 2007

This study examines the joint and splice of wooden structure at Geunjeongjeon Hall of Gyengbok Palace, which was constructed in the late Joseon Dynasty. The scope of the study is on the part of columns, the bracket sets, and the frame structure. This research also deals with the relationship between vortical load and horizontal load. Firstly, the examination of the joint and splice methods between the pillar and penetrating ties is on the joint and splice methods of the outer and corner. Through the investigation, it is verified that the joint methods between pillar and penetrating tie on the outer and corner pillars is the method of Sagal joints(cross joints, 사개맞춤). Joints used between pillar and penetrating tie are dovetailed tenon joints, between columns and Anchogong(안초공), between columns and Choikgong(초익공) are tenon joint(장부맞춤). Secondly, the examination of the joint and splice methods of the bracket set is on that of Salmi and Cheomcha(첨차), and Salmi and Janghyeo(장혀). Joints used between Salmi and Cheomcha, Salmi and Janghyeo are halved joint, and between each Janghyeo are stepped dovetailed splice. It is Cheomcha that is used the Jujang-Cheomcha(주장첨차) on center line. Therefore it is connected with each bracket set, which gets to is the strong system, easy and convenient on the construction of that. Thirdly, the frame structure of wooden architecture in royal palace is consist of purlins and beams, Janghyeo(장혀, timber under purlin), tall columns, king posts, etc. Through the investigation, it is verified that the joint and splice methods between purlins and beams are used with the methods of Sungeoteok joint(숭어턱맞춤). It is verified that the joint and splice methods between beams and high columns are used with methods of mortise and tenon joint(장부맞춤), is highly related with tensile force. To reduce the separation of parts, sangi(산지) and tishoi(띠쇠) are used as a counterproposal, which were generally used for architecture in royal Palaces in the late Joseon Dynasty and continued to be used until these days common wooden architecture.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.553-558
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• 2010

The behavior of composite piles composed of steel pipe pile in the upper part and concrete pile in the lower part by a mechanical splicing joint was examined by field lateral load tests and bending tests. A total of 7 piles including two instrumented piles for bending test were installed. The soil profile consists of soft clay with weak silt with shallow groundwater level. Laboratory tests were carried out to determine the basic soil characteristics and the strength parameters. This paper presents the composite pile behavior with various portions of the upper steel pile: 0, 20, 30, and 45% of the pile embedded pile length. Three-point bending tests were performed to investigate the stress-strain relation at the mechanical joint. Based on these test results, the behavior of composite piles with various upper steel pile length are evaluated and the stability of mechanical joints are examined. Through comparisons with results of field load tests, it was found that lateral load carrying capacity of the composite piles increased and deflections of the composite piles decreased with increasing the upper steel piles. The mechanical joint was proved to retain its structural stability against the tested load conditions. Economical benefits of composite pile of this kind can be gained by setting adequately the length of the upper steel pipe piles.

• Clinics in Shoulder and Elbow
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• v.17 no.3
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• pp.120-126
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• 2014

Background: To compare the treatment of the proximal humerus fracture using a Polarus nail or Philos plate, we aimed to analyze the functional recovery and the factors affecting the selection between the two types of surgery. Methods: The study included 107 patients with proximal humerus fracture who underwent surgery at our institution. Of these patients, 67 underwent surgery with Polarus nails (G1) and 40 with Philos plates (G2). In G1, the cases of two- and three-part fractures were 60 and 7 cases, in G2, the cases of two-, three-, and four-part fractures were 28, 10, and 2 cases, respectively. The average age was 61 years old, and the average follow-up period was 32.5 months. We compared radiological results, the functional recovery retrospectively. Results: The radiological union time was 6.8 weeks and 8.7 weeks on average in G1 and G2 (p < 0.05). At the one-year follow-up period, these were visual analogue scale (VAS) 1.355, forward flexion (FF) 130.968, external rotation (ER) 50.161, internal rotation (IR) L2 in G1, and VAS 0.781, FF 135.806 ER 51.25, IR L1 in G2, respectively, showing no significant differences between the two groups (p > 0.05). Similar observations were made at the final follow-up. In terms of functional recovery, no significant differences were seen at the one-year or at the final follow-up period (p > 0.05). Conclusions: For the surgical treatment of proximal humeral fracture, the selection of the type of surgery is affected by the fracture pattern. However, both methods give satisfactory outcomes and do not show significant differences in the functional outcome after the surgery.

• Structural Engineering and Mechanics
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• v.83 no.5
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• pp.693-707
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• 2022

Bonded joints have proven their performance against conventional joining processes such as welding, riveting and bolting. The single-lap joint is the most widely used to characterize adhesive joints in tensile-shear loadings. However, the high stress concentrations in the adhesive joint due to the non-linearity of the applied loads generate a bending moment in the joint, resulting in high stresses at the adhesive edges. Geometric optimization of the bonded joint to reduce this high stress concentration prompted various researchers to perform geometric modifications of the adhesive and adherends at their free edges. Modifying both edges of the adhesive (spew) and the adherends (bevel) has proven to be an effective solution to reduce stresses at both edges and improve stress transfer at the inner part of the adhesive layer. The majority of research aimed at improving the geometry of the plate and adhesive edges has not considered the effect of temperature and water absorption in evaluating the strength of the joint. The objective of this work is to analyze, by the finite element method, the stress distribution in an adhesive joint between two 2024-T3 aluminum plates. The effects of the adhesive fillet and adherend bevel on the bonded joint stresses were taken into account. On the other hand, degradation of the mechanical properties of the adhesive following its exposure to moisture and temperature was found. The results clearly showed that the modification of the edges of the adhesive and of the bonding agent have an important role in the durability of the bond. Although the modification of the adhesive and bonding edges significantly improves the joint strength, the simultaneous exposure of the joint to temperature and moisture generates high stress concentrations in the adhesive joint that, in most cases, can easily reach the failure point of the material even at low applied stresses.