• Journal of Korean Society of Steel Construction
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• v.16 no.3 s.70
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• pp.377-385
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• 2004

An experimental and analytical study on the behavior of the wall-support joint in SC(steel plate-concrete) structure was performed. Nine full-scale specimens were tested with a horizontal monotonic load, all acting in the same plane, causing a uni-axial moment on the SC structure's wall-support beam joint. The main focus is to examine thenonlinear behavior and ultimate strength of the SC wall-support joint. The effects of parameters, such aslocation of support, thickness of the steel plate, and size of support, were studied. The yield strength and ultimate strength of the plate-concrete wall was defined by examining the load-deflection relationship, showing the tension membrane action.

• Steel and Composite Structures
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• v.1 no.3
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• pp.295-312
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• 2001

The purpose of this paper is to propose a new type of steel reinforced concrete (SRC) beam-column joints and to examine the structural performance of the proposed joints, which simplify the construction procedure of steel fabrication, welding works, concrete casting and joint strengthening. In the proposed beam-column joints, the steel element of columns forms continuously built-in crossing of H-sections (${\Box}$), with adjacent flanges of column being connected by horizontal stiffeners in a joint at the level of the beam flanges. In addition, simplified lateral reinforcement (${\Box}$) is adopted in a joint to confine the longitudinal reinforcing bars in columns. Experimental and analytical studies have been carried out to estimate the structural performance of the proposed joints. Twelve cruciform specimens and seven SRC beam-column subassemblage specimens were prepared and tested. The following can be concluded from this study: (1) SRC subassemblages with the proposed beam-column joints show adequate seismic performances which are superior to the demand of the current code; (2) The yield and ultimate strength capacities of the beam-to-column connections can be estimated by analysis based on the yield line theory; (3) The skeleton curves and the ultimate shear capacities of the beam-column joint panel are predicted with a fair degree of accuracy by considering a simple stress transfer mechanism.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1796-1799
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• 1997

This thersis presents precise position control emthods of a 3-PRPS in-parallel manipulator for industrial applications such as assembly of highly integrated semiconductors and microsurgery. Since real-time ontrol is one of the most important issues required for industrial application, the experimental hardware is set up with a VME based DSP controller. In the 3-PRPS parallel mainpulator, structurally existing frictiion at three horizontal links considerably degrades the precise position control. In order to compensate the friction of the horizontal links in the joint space, a disturbance compensation usign disturbance and velocity observers has been proposed and investigated. We analyzed the decision method of eigenvalues of the disturbance observer and the effects of the control resulted form tehsystem model errors. Through a series of simulations and experiments, we see that the methods is capable of compensating variations of the robot parameters such as inertia and damping as well as the joint friction. Experiments show that the disturbance compensation method usign disturbance and velocity observer is very effective to compensate the friction. Compared with conventional PID position control, it decreased position errors ina circular motion by approximately 70%.

• Earthquakes and Structures
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• v.9 no.1
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• pp.233-256
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• 2015

This paper presents an experimental study to assess the effectiveness of using ferrocement to strengthen deficient beam-column joints. Ferrocement is proposed to protect the joint region through replacing concrete cover. Six exterior beam-column joints, including two control specimens and four strengthened specimens, are prepared and tested under constant axial load and quasi-static cyclic loading. Two levels of axial load on column (0.2fc'Ag and 0.4fc'Ag) and two types of skeletal reinforcements in ferrocement (grid reinforcements and diagonal reinforcements) are considered as test variables. Experimental results have indicated that ferrocement as a composite material can enhance the seismic performance of deficient beam-column joints in terms of peak horizontal load, energy dissipation, stiffness and joint shear strength. Shear distortions within the joints are significantly reduced for the strengthened specimens. High axial load (0.4fc'Ag) has a detrimental effect on peak horizontal load for both control and ferrocement-strengthened specimens. Specimens strengthened by ferrocement with two types of skeletal reinforcements perform similarly. Finally, a method is proposed to predict shear strength of beam-column joints strengthened by ferrocement.

• Journal of Welding and Joining
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• v.21 no.5
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• pp.568-574
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• 2003

In the welding for the steel structure of H-beam with mild steel and 490N/$\textrm{mm}^2$ high tensile steel, we applied the fillet weld mostly and 6-8mm weld length(AISC-spec.). And a new developed metal-cored-wire is used in automatic welding as well as semi-automatic welding. In this study we have attempted to raise the welding productivity and to stabilize the quality on horizontal positions of fillet welding with the following items: - We improved the weld productivity using metal based cored wire with a high deposition rate in the steel structure of H-beam. - We tested the weldability and evaluated the quality of the weldmetal by horizontal fillet $CO_2$ welding. The process is carried out in combination with a special purpose metal-based FCW with excellent resistance to porosity and high welding speed. - We studied the micro structure of the weldmetal by the various welding conditions. - We studied the effect of welding residual stress by the welding conditions in T-joint. Therefore, it can be assured that more productive and superior quality of the weldmetal can be taken from this study results.

• Korean Journal of Applied Biomechanics
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• v.15 no.4
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• pp.97-104
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• 2005

Previous studies of kinematic analysis of golf swing usually dealt with variations vertically. The purpose of the study was to examine the horizontal hip joints motion of the fifteen male professional golfers during driver swinging. Kinematic variables were calculated by the Kwon3D motion analysis program. Paired t-tests and one-way ANOVA were used to compare the hip height, distance, displacement, and position differences. Results showed that there were no hip height changes and no hip height differences between left and right hip from address to impact. The axis of the backswing was braced right hip, the axis of the downswing was moving left hip. Hips position at the top of the backswing showed that hips move to target prior to hands, which means the sequential motion of the chain linked body segments. From address to impact, left hip moving distance was longer than right hip(p<.001), but during the whole swing, right hip moving distance was longer than left hip(p<.001). Hip rotation angle to target line was $-48.14{\pm}9.32^{\circ}$ at top of the backswing, $40.88{\pm}8.44^{\circ}$ at impact, and $104.70{\pm}8.14^{\circ}$ at finish.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.9 no.1
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• pp.13-18
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• 1979

The purpose of this study was to investigate the radiographic images of Temporomandibular joint trouble patients. This study included 186 patients with the chief complaints of TMJ pain and dysfunction. Their age ranged from 17 to 68 years. All patients were identified in the department of Dental mary of College of Dentistry, Seoul National University, Apr. 1978 to Jun. 1979. The author has observed the radiographic variations of two positions of condylar head taken by modified transcranial oblique-lateral projection, which are one in centric occlusion and the other in 1 inch(2.54㎝) mouth open. The results were obtained as follows; 1. In centric occlusion, the distances and positional relationship between the summit of condylar head and the deepest point of articular fossa revealed more or less large variations; Normal range is of 37.9%, anterior displacement of 37.3% and posterior displacement of 22.6%. 2. In the horizontal movement of condylar heads when on 1 inch mouth open, it was revealed that normalrange was of 46.5%, anterior displacement of 12.3%, posterior displacement of 41. 1 %. 3. In the positional interrelationship of both condylar heads when on 1 inch mouth open, it was revealed that symmetry(71. 5%) occurred approximately 2.5 times as many as asymmetry. 4. In both centric occlusion and 1 inch mouth open, it was showed that almost all estimated figures were greater in male than in female, and in the horizontal movement of condylar head when on 1 inch open, it was showed that hypermobility was dominant in male and hypomobility in female.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.298-303
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• 2016

Owing to the advantages of reduced weight and wind effect, the space-framed towers that consist of vertical and horizontal members of circular hollow tubular sections have been adopted widely for various purposes. It is critical to guarantee the strengths of tubular joints where vertical and horizontal members are connected structurally to make the entire space-framed system behave as a single tower structure. In this study, a strength evaluation was conducted for T-type tubular joints subjected to the concurrent action of compression and bending. Three of the available design codes, i.e., AISC, Eurocode 3, ISO 19902 were investigated and a design equation was suggested for an ultimate strength interaction between the axial force and bending moment based on nonlinear finite element analyses by selecting the slenderness ratios at the joints as major parameters.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.3
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• pp.253-260
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• 1999

Main objective of this study is to examine the hysteretic behaviors and to evaluate the capacity of precast concrete (PC) large panel structures simulated from the prototype of 15-story building, Two 1/2 scaled precast concrete wall specimens and one monolithic reinforced concrete specimen were designed and tested under the cyclic loading conditions. The main parameter of test specimens in PC large panel structure is the type of details for vertical continuity of vertical steel in horizontal joint. Also the behaviors of PC large panel structures are compared with that of monolithic reinforcement concrete wall structure. From the results, the stiffness and energy dissipation ratio of the precast concrete specimens are shown little bit lower than those of monolithic reinforced concrete specimen. In the PC large panel structures, the specimen connected vertically by welding (strong connection) showed higher strength than that of the specimen connected vertically by joint box. However the failure pattern of the former showed more brittle than that of the latter due to the diagonal compressive failure of wall panels.

• Computers and Concrete
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• v.27 no.2
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• pp.99-109
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• 2021

Experimental and discrete element methods were used to investigate the effects of echelon non-persistent joint on the failure behaviour of joint's bridge area under uniaxial compressive test. Concrete samples with dimension of 150 mm×100 mm×50 mm were prepared. Uniaxial compressive strength and tensile strength of concrete were 14 MPa and 1MPa, respectivly. Within the specimen, three echelon non-persistent notches were provided. These joints were distributed on the three diagonal plane. the angle of diagonal plane related to horizontal axis were 15°, 30° and 45°. The angle of joints related to diagonal plane were 30°, 45°, 60°. Totally, 9 different configuration systems were prepared for non-persistent joint. In these configurations, the length of joints were taken as 2 cm. Similar to those for joints configuration systems in the experimental tests, 9 models with different echelon non-persistent joint were prepared in numerical model. The axial load was applied to the model by rate of 0.05 mm/min. the results show that the failure process was mostly governed by both of the non-persistent joint angle and diagonal plane angle. The compressive strengths of the specimens were related to the fracture pattern and failure mechanism of the discontinuities. It was shown that the shear behaviour of discontinuities is related to the number of the induced tensile cracks which are increased by increasing the joint angle. The strength of samples increase by increasing both of the joint angle and diagonal plane angle. The failure pattern and failure strength are similar in both methods i.e. the experimental testing and the numerical simulation methods.