• Proceedings of the KWS Conference
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• 1996.05a
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• pp.96-98
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• 1996

Welding of corner area across the edge is a difficult problem in robotized arc welding system, especially when continuously-welded leakage-proof product is required. This paper presents the methodology of cooperation plan of an arc welding robot and 1 or 2 axis welding manipulators for corner area welding. Welding trajectory for the robot is generated using clothoid curves; symmetrical double clothoid curve or unsymmetrical clothoid curve depending on the nature of the workpiece. The clothoid curve is first formulated for the case of linear type positioning table and then applied to the case of rotary type manipulator. The methodology is then illustrated for practical downhand welding situations.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.534-537
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• 2005

Free Vibration Analysis using Non-dimensional Dynamic Influence Function (NDIF) is extended to arbitrarily shaped plates including polygonal plates. Since the corners of polygonal plates have indefinite normal directions and additional boundary conditions related to a twisting moment at a corner along with moment and shear force zero conditions, it is not easy to apply the NDIF method to polygonal plates wi th the free boundary condition. Moreover, owing to the fact that the local polar coordinate system, which has been introduced for free plates with smoothly varying edges, cannot be employed for the straight edges of the polygonal plates, a new coordinate system is required for the polygonal plates. These problems are solved by developing the new method of modifying a corner into a circular arc and setting the normal direction at the corner to an average value of normal direct ions of two edges adjacent to the corner. Some case studies for plates with various shapes show that the proposed method gives credible natural frequencies and mode shapes for various polygons that agree well with those by an exact method or FEM (ANSYS).

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.7
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• pp.79-88
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• 2018

In the late Koryo Dynasty~early Joseon Dynasty, nationwide distribution of Ondol prompted the formation of ㄱ-shaped corner space. From this background, the spatial form changed according to the space function. In the case where the ondol is located in the bent portion, it would have formed a similar spatial form nationwide at the beginning of the 16th century. Until the middle of the 16th century the receptionists and the family rituals were carried out in the inner of the house, so ㄱ-shaped corner space gradually expanded. Also a special structure type using fultile rafters was used to cover the upper structure of the extended folded space. From the 17th century, ㄱ-shaped corner space was varied from wide and high to narrow and low. In addition to this, the space function of ㄱ-shaped corner is a small hall, a wooden floored room, and the kitchen. And Their spatial form also changes over time.

• Geomechanics and Engineering
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• v.29 no.3
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• pp.339-348
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• 2022

The bored tunneling method is generally preferred for urban tunnel construction, However the cut & cover tunnel is still necessary for special conditions, such as metro station and access structures. In some case, deep excavation for cut & cover construction is planed of irregular and unusual shape, as a consequence, the convex and concave corner is often encountered during that excavation. In particular, discontinuity or imbalance of the support structure in the convex corner can lead to collapse, which may result in damages and casualties. In this study, the behavior of the convex corner of retaining structure were investigated using 3-dimensional numerical models established to be able to simulate the split-shaped behavior of convex corners. To improve the stability in the vicinity of the convex corner, several stabilizing measures were proposed and estimated numerically. It is found that linking two discretized wales at the convex corner can effectively perform the control of deformation. Furthermore, it was also confirmed that the stabilizing measures can be enhanced when the tie-material linking two discretized wales is installed at the depth of the maximum wall deflection.

• Transactions of the Korean Society of Mechanical Engineers
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• v.6 no.3
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• pp.232-238
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• 1982

The behavior of corner crack propagation by unidirectional plane bending fatigue was investigated in the butt welded joints of SS41 and SM50 steel plates including an edge through-thickness notch. The properties of fatigue crack propagation were inspected in the weld metal, heat-affected zone, and base metal of the welded joints. Main results obtained are as follows; (1) When a plate with an edge through-thickness notch is loaded by plane bending fatigue in indirection, the 2 variant corner cracks on the upper and lower edge of the plate are initiated and propagated respectively from the notch. (2) In case of a specimen containing a corner crack, it is more reasonable to estimate the crack propagation rate by area of fracture surface than by crack surface length. (3) The rate of fatigue crack propagation becomes faster in the following order; weld metal, heat-affected zone, and base metal. (4) The specimen including reinforcement shape is rapidly failed throughout bond due to effect of its shape when the repeated load exceeds a certain cycle.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2005.09a
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• pp.67-88
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• 2005

Mold-Flow 3 Die Stack CSP of Mold array packaging with different Gate types. As high density package option such as 3 or 4 die stacking technologies are developed, the major concerning points of mold related qualities such as incomplete mold, exposed wires and wire sweeping issues are increased because of its narrow space between die top and mold surface and higher wiring density. Full 3D rheokinetic simulation of Mold flow for 3 die stacking structure case was done with the rheological parameters acquired from Slit-Die rheometer and DSC of commercial EMC. The center gate showed severe void but corner gate showed relatively better void performance. But in case of wire sweeping related, the center gate type showed less wire sweeping than corner gate types. From the simulation results, corner gate types showed increased velocity, shear stress and mold pressure near the gate and final filling zone. The experimental Case study and the Mold flow simulation showed good agreement on the mold void and wire sweeping related prediction. Full 3D simulation methodologies with proper rheokinetic material characterization by thermal and rheological instruments enable the prediction of micro-scale mold filling behavior in the multi die stacking and other complicated packaging structures for the future application.

• Transactions of Materials Processing
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• v.8 no.6
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• pp.604-611
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• 1999

This paper is concerned with the family of parts that generally feature a central hub with radial protrusions. As opposed to conventional forward and backward extrusion, in which the material flows in a direction parallel to that of the punch or die motion, the material flows perpendicular to the punch motion in radial extrusion. Three variants of radial extrusion of a collar or flange are investigated. Case I involves forcing a cylindrical billet against a flat die, Case II involves deformation against a stationary punch recessed in the lower die, and Case III involves both the upper and lower punches moving together toward the center of the billet. Extensive simulational work is performed with each case to see the process conditions in terms of forging load, balanced and symmetrical flow in the flange. Also, the effect of the gap size and die corner radii to the material flow are investigated. In this study, the forming characteristics of radial extrusion will be considered by comparing the forces, shapes etc. The design factors during radial extrusion are investigated by the rigid-plastic FEM simulation.

• Journal of Astronomy and Space Sciences
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• v.26 no.4
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• pp.667-676
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• 2009

The payload can be classified as a passive and active type. Generally radar satellite to acquire specific information through various radar images will use the SAR (Synthetic Aperture Radar) as active type payload. the principal of SAR satellite is to receive the signal returned from certain objects and/or surfaces in order to construct an radar image. The data acquired from the satellite in its real orbit shall be needed to perform successful CAL/VAL (Calibration & Validation) because the SAR satellite have to receive the returned signal for SAR image construction. In order to do the above, the returned signal shall be related to ground targets. Especially ground target is the corner reflector (CR) for CAL/VAL. Generally the reflector has various types and shapes. Their selection can be dependent on characteristics and mission objectives of SAR satellite. In this paper, reflector focused on the optimal case and effective case has been studied and then the trihedral corner reflector under this study has been designed and its performance also analyzed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.3
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• pp.18-24
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• 2011

This paper presents that the yield strength of the pressure sensor with a double boss diaphragm structure can be improved as the grooves are formed at the corner of the diaphragm bridge. Generally the boss structure is widely used for the low-pressure sensor, of which the sensitivity is not enough in case of the small diaphragm size limited by a chip size constraint. The double boss structure pressure sensor exhibits a great sensitivity, but suffers from the low yield strength problem due to the high stress occurred at the corner of the diaphragm bridge to be limited in the operating range. ANSYS simulation is performed by changing the length of the groove from 0.5${\mu}m$ to 10${\mu}m$ at the corner of the diaphragm bridge of the double boss structure pressure sensor. The maximum stress is analyzed at the corner of the diaphragm bridge, the edge of the diaphragm bridge, and the position of the piezoresistive sensor. Consequently, in case the length of the groove from the edge of the diaphragm is 6${\mu}m$ or greater, the stress occurred in the corner of the bridge is less than the stress acting on a piezoresistive element.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.4
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• pp.703-713
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• 2001

Mechanical joints such as bolted or riveted joints are widely used in structural components and the reliable determination of the stress intensity factors for corner cracks in mechanical joints is needed to evaluate the safety and fatigue life. This paper analyzes the mixed-mode stress intensity factors of surface and deepest points for quarter elliptical corner cracks in mechanical joints by weight function method and the coefficients included in weight function are determined by finite element analyses for reference loadings. The extended form of the weight function method for two-dimensional mixed-mode to three-dimensional is presented and the number of terms in weight function is determined by comparing the results for the different number of terms. The amount of clearance is an important factor in evaluating the severity of elliptical corner cracks in mechanical joints and even horizontal crack normal to the applied load is under mixed-mode in the case that clearance exists.