• Journal of Korean Foot and Ankle Society
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• v.12 no.1
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• pp.86-92
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• 2008

Purpose: To evaluate the safety and prognostic factors of intramedullary nailing of distal tibia fractures in terms of function and symptoms of the ankle joint. Materials and Methods: We retrospectively analyzed 22 distal tibial fractures with intramedullary nailing. The mean duration of follow-up was 43 months. We reviewed medical records to describe each case. We measured radiographic parameters such as fracture configuration, arthritic change of the ankle joint and status of reduction. We also assessed clinical results by AOFAS ankle hind foot scoring system, degree of pain by VAS and range of motion to find out prognostic factors for functional result of the ankle joint. Results: Bone healing was obtained in all cases without any wound complications. Mean AOFAS ankle score was 94. There were 4 cases with mild (VAS<3/10) ankle pain and 2 cases with mild limitation of ankle motion. The comminution of fracture had a significant relationship with delayed angular deformity of ankle joint (p=0.032). There was no other significant parameter affecting ankle joint function except the location of nail-end. Conclusion: Intramedullary nailing in distal tibia fracture is a safe and effective procedure. But further study may need to evaluate the relationship between the position of nail-end and the function of ankle joint.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.801-804
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• 2011

The concept design of joint part between propellant tank and feeding line for launch vehicle has been performed with the case study of oversea launch vehicles. we carried out, for the several configurations, numerical flow analyses to find the joint configuration which promises high flow uniformity at the outlet. There were a little difference in the numerical results, because the length of feeding lines are sufficiently long to stabilize the flow field.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.10 s.253
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• pp.1187-1193
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• 2006

Traditionally, the continuum-based topology optimization methods employing the SIMP technique have been used to design compliant mechanisms. Although they have been successful, the optimized mechanisms by the methods are usually difficult to manufacture because of their geometrical complexities. The objective of this study is to develop a topology optimization method that can produce easy-to-fabricate mechanism structure. The proposed method is a ground beam method where beam connectivity is controlled by the beam joint stiffness. In this approach, beam joint stiffness determines the mechanism configuration. Because b the ground structure beams have uniform thicknesses varying only discretely, the resulting mechanism topologies become easily manufacturable.

• 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.

• International Journal of Ocean System Engineering
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• v.2 no.2
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• pp.82-91
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• 2012

Fillet welding is widely used in the assembly of ships and offshore structures. The T-joint configuration is frequently reported to experience fatigue damage when a marine structure meets extreme loads such as storm loads. Fatigue damage is affected by the magnitude of residual stresses on the weld. Recently, many shipping registers and design guides have required that the fatigue strength assessment procedure of seagoing structures under wave-induced random loading and storm loading be compensated based on the effect of residual stresses. We propose a computational procedure to analyze the residual stresses in a T-joint. Residual stresses are measured by the X-ray diffraction (XRD) method, and a 3-D finite element analysis (FEA) is performed to obtain the residual stress profile in the T-joint. The proposed finite element model is validated by comparing experiments with computational results, and the characteristics of the residual stresses in the T-joint are discussed.

• Steel and Composite Structures
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• v.39 no.3
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• pp.337-352
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• 2021

The study presented experimental and numerical investigation on the seismic performance of steel reinforced concrete (SRC) L-shaped column- reinforced concrete (RC) beam joints. Various parameters described as steel configuration form, axial compressive ratio, loading angle, and the existence of slab were examined through 4 planar joints and 7 spatial joints. The characteristics of the load-displacement response included the bearing capacity, ductility, story drift ratio, energy-dissipating capacity, and stiffness degradation were analyzed. The results showed that shear failure and flexural failure in the beam tip were observed for planar joints and spatial joint, respectively. And RC joint with slab failed with the plastic hinge in the slab and bottom of the beam. The results indicated that hysteretic curves of spatial joints with solid-web steel were plumper than those with hollow-web specimens. The capacity of planar joints was higher than that of space joints, while the opposite was true for energy-dissipation capacity and ductility. The high compression ratio contributed to the increase in capacity and initial stiffness of the joint. The elastic and elastic-plastic story deformation capacity of L-shaped column frame joints satisfied the code requirement. A design formula of joint shear resistance based on the superposition theory and equilibrium plasticity truss model was proposed for engineering application.

• Computers and Concrete
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• v.26 no.6
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• pp.565-576
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• 2020

Experimental and discrete element methods were used to investigate the effects of angle of Y shape non-persistent joint on the tensile behaviour of joint's bridge area under brazilian test. concrete samples with diameter of 100 mm and thikness of 40 mm were prepared. Within the specimen, two Y shape non-persistent notches were provided. The large notch lengths were 6 cm, 4 cm and 2 cm. the small notch lengths were 3 cm, 2 cm and 1 cm. The angle of larger notch related to horizontal axis was 0°, 30°, 60°, 90°. Totally, 12 different configuration systems were prepared for Y shape non-persistent joints. Also, 18 models with different Y shape non-persistent notch angle and notch length were prepared in numerical model. The large notch lengths were 6 cm, 4 cm and 2 cm. the small notch lengths were 3 cm, 2 cm and 1 cm. The angle of larger notch related to horizontal axis was 0, 30, 60, 90, 120 and 150. Tensile strength of model materil was 1 MPa. The axial load was applied to the model by rate of 0.02 mm/sec. This testing showed that the failure process was mostly governed by the Y shape non-persistent joint angle and joint length. The tensile strengths of the specimens were related to the fracture pattern and failure mechanism of the discontinuities. It was shown that the tensile behaviour of discontinuities is related to the number of the induced tensile cracks which are increased by increasing the joint length and joint angle. The minimum tensile strength occurs when the angle of larger joint related to horizontal axis was 60°. Also, the maximum compressive strength occurs when the angle of larger joint related to horizontal axis was 90°. The tensile strength was decreased by increasing the notch length. The failure pattern and failure strength are similar in both methods i.e. the experimental testing and the numerical simulation methods.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1281-1284
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• 1997

In this article, the configuration of weight lifer is analyzed using manipulibility polytope. After modeling body as 7-link redundant robot, optimal joint angles during first stage are searched by dynamic programmi technique and compared with standard reference data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.3
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• pp.285-297
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• 2016

In this paper, a centralized mmWave-based multi-spot beam cellular system architecture having such a base station equipped with a plurality of beam-forming antennas, multi-layered dynamic cell configuration method as one of key concepts of this system operation and a mobility management method based on it are introduced. To estimate the performance of new system, system simulation was performed under the ideal environment without blockage. These results show the possibility that system capacity can be dramatically increased and mobility performance similar to the existing cellular system may be achieved.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.204-209
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• 2004

This paper describes dynamic manipulability analysis of robotic arms moving in viscous fluid. The Manipulability is a functionality of manipulator system in a given configuration and under the limits of joint ability with respect to the tasks required to bt performed. To investigate the manipulability of underwater robotic arms, a modeling and analysis method are presented. The dynamic equation of motion of underwater manipulator is derived from the Lagrange - Euler equation considering with the hydraulic forces caused by added mass, buoyancy and hydraulic drag. The hydraulic drag term in the equation: is established as analytical form using Denavit - Hartenberg (D-H) link coordination of manipulator. Two analytical approaches based on Manipulability Ellipsoid are presented to visualize the manipulability of robotic arm moving in viscous fluid. The one is scaled ellipsoid which transforms the boundary of joint torque to acceleration boundary of end-effector by normalizing the torque in joint space while the other is shifted ellipsoid which depicts total acceleration boundary of end-effector by shifting the ellipsoid in work space. An analysis example of 2-link manipulator with proposed analysis scheme is presented to validate the method.