• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.813-817
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• 1995

Structural analysis of horizontal cold chamber die casting machine is performed by the FEM. The analyzed model is made up of stationary die platen,movable die platen,link housing platen, C-frame, and tie bar which mainly undertake die locking force and injection force. In modeling, compression gap elements are used for to simulate contacting condition between tie bar and movable die platen, movable die platen and base frame, and link housing and base frame. Unbalanced die locking force imposed on four tie bars are considered. As the results, the deformed shape and the stresses of the die casting machine are given.

• Journal of Drive and Control
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• v.11 no.4
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• pp.46-52
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• 2014

This study suggests a small-sized screw decanter specialized for dredging sites. Generally, conventional screw decanters are composed of a cylinder and a cone. However, the suggested screw decanter simply has a cone based on a cone-type bowl structure. In this research, a commercial analysis tool is used to establish an optimal design for the bowl and the screw conveyor. Moreover, the base frame, where the main bearings that support the spindle of the bowl and the screw conveyor are installed, is optimally designed considering the weight of the rotating body and the deflection caused by the high centrifugal force. Furthermore, the natural frequency range of the spinning body, the bowl and the screw conveyor, is applied to this base frame; it is designed not to correspond to the resonance frequency range and achieves stability as a result. This study suggests an optimal design for the rotating body and the base frame of a screw decanter considering its vibration characteristics. Such a design will prevent overuse of materials and help to reduce the weight and volume-and the price-of a screw decanter.

• Steel and Composite Structures
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• v.1 no.2
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• pp.187-200
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• 2001

Most of the portal frames are designed these days by the application of plastic analysis, with the normal assumption being made that the column bases are pinned. However, the couple produced by the compression action of the inner column flange and the tension in the holding down bolts will inevitably generate some moment resistance and rotational stiffness. Full-scale portal frame tests conducted during a previous research program had suggested that this moment can be as much as 20% of the moment of resistance of the column. The size of this moment of resistance is particularly important for the design of the tensile capacity of the holding down bolts and also the bearing resistance of the foundation. The present research program is aiming at defining this moment of resistance in simple design terms so that it could be included in the design of the frame. The investigation also included the study of the semi-rigid behaviour of the column base/foundation, which, to a certain extent, affects the overall loading capacity and stiffness of the portal frames. A series of column bases with various details were tested and were used to calibrate a finite element model which is able to simulate the action of the holding down bolts, the effect of the concrete foundation and the deformation of the base plate.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.475-478
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• 2004

In this paper, a CSSMA/AI MAC protocol for data services in packet CDMA network is presented. The proposed protocol is based on the code status sensing and reservation scheme. In the proposed protocol, the base station broadcast the rode status on a frame-by-frame basis just before the beginning of each preamble transmission, and the mobile station transmits a preamble for reserving a randomly selected code based on the received code status. After having transmitted the preamble, the mobile station listens to the downlink of the selected rode and waits for the base station reply. If this reply indicates that the code has been correctly acquired, it continues the packet transmission lot the rest of the frame. If there are other packets waiting for transmission, the base station broadcasts the status of the code as reserved, and the mobile station transmits a packet through the reserved code for the successive frames.

• Earthquakes and Structures
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• v.10 no.2
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• pp.293-311
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• 2016

A parametric study on the nonlinear seismic response of isolated reinforced concrete structural frame is presented. Three prototype frames designed according to the 1954 Hellenic seismic code, with number of floor ranging from 1 to 3 were considered. These low rise frames are representative of many existing reinforced concrete buildings in Greece. The efficacy of the implementation of both lead rubber bearings (LRB) and friction pendulum isolators (FPI) base isolation systems were examined. The selection of the isolation devices was made according to the ratio $T_{is}/T_{fb}$, where Tis is the period of the base isolation system and $T_{bf}$ is the period of the fixed-base building. The main purpose of this comprehensive study is to investigate the effect of the isolation system period on the seismic response of inadequately designed low rise buildings. Thus, the implementation of isolation systems which correspond to the ratio $T_{is}/T_{fb}$ that values from 3 to 5 is studied. Nonlinear time history analyses were performed to investigate the response of the isolated structures using a set of three natural seismic ground motions. The evaluation of each retrofitting case was made in terms of storey drift and storey shear force while in view of serviceability it was made in terms of storey acceleration. Finally, the maximum developed displacements and the residual displacements of the isolation systems are presented.

• Earthquakes and Structures
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• v.15 no.3
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• pp.319-334
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• 2018

In this paper, an analytical study was carried out to propose an optimum base-isolated system for the design of steel structures equipped with lead rubber bearings (LRB). For this, 5 and 10-storey steel moment resisting frames (MRFs) were designed as Special Moment Frame (SMF). These two-dimensional and three-bay frames equipped with a set of isolation systems within a predefined range that minimizes the response of the base-isolated frames subjected to a series of earthquakes. In the design of LRB, two main parameters, namely, isolation period (T) and the ratio of strength to weight (Q/W) supported by isolators were considered as 2.25, 2.5, 2.75 and 3 s, 0.05, 0.10 and 0.15, respectively. The Force-deformation behavior of the isolators was modelled by the bi-linear behavior which could reflect the nonlinear characteristics of the lead-plug bearings. The base-isolated frames were modelled using a finite element program and those performances were evaluated in the light of the nonlinear time history analyses by six natural accelerograms compatible with seismic hazard levels of 2% probability of exceedance in 50 years. The performance of the isolated frames was assessed in terms of roof displacement, relative displacement, interstorey drift, absolute acceleration, base shear and hysteretic curve.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.970-974
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• 1993

This paper is concerned with an automatic generation of BOM (Bill Of Material) for a bicycle frame set using a knowledge based system. The major components module system includes : (1) Part information retrieval in CAD drawing, (2) BOM code generation rule, and (3) Database interface. The knowledge based system includes a rule base and a fact base. The fact base consists of basic, variant, and optional components of the standard BOMs of frame sets. The rule contains rules for generating new BOM code in case that the specified is not in the database. The system was implemented on a SUN workstation under Open Windows environments. AutoCAD for CAD drawing was also used.

• Structural Engineering and Mechanics
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• v.29 no.6
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• pp.659-671
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• 2008

A procedure to analyse the space frame structure fixed at base as well as resting on sliding bearing using total or absolute displacement in dynamic equation is developed. In the present method, the effect of ground acceleration is not considered as equivalent force. Instead, the ground acceleration is considered as a known value in the acceleration vector at degree of freedom corresponding to base of the structure when the structure is in non-sliding phase. When the structure is in sliding phase, only a force equal to the maximum frictional resistance is applied at base. Also, in this method, the stiffness matrix, mass matrix and the damping matrix will not change when the structure enters from one phase to another. The results obtained from the present method using absolute displacement approach are compared with the results obtained from the analysis of structure using relative displacement approach. The applicability of the analysis is also demonstrated to obtain the response of the structure resting on sliding bearing with restoring force device.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1337-1342
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• 2008

The whisker grows at the plating of a lead frame so that it causes the serious problem like the short. To prove this case, many people have studied the cause and influence of the tin whisker growth. This study explains the grain size affects the growth of the whisker in the lead frame. By these studies about the whisker, the whisker growth is discovered by stresses generated by the intermetallic compound and CTE mismatch in both plating and base metal. The stresses or lattice defect generated in the plating process changes grain structure of plating. Consequently, these various stresses are stabilized by forming unspecified whiskers through lots of grain boundaries. Because the grain boundary is the path of the whisker growth, the smaller grain size exists, the more whiskers grow.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.7
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• pp.1505-1514
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• 1997

In this paper, a temporally adaptive layered image sequence coding technique employing H.261 is proposed. In the proposed technique, the frame rate of the base layer is adjusted according to the temporal activity measure based on the rate-distortion function. The base layer is encoded using the H.261. Then, the full frame-rate error image is formed by comparing the original image and the interpolated version of the reconstructed base layer image. The enhancement layer is algo encoded using H.261 but with leaky prdiction to provide robust error resilience. The simulation results show that the proposed technique provides better performance than the twin-H.261 with leaky prediction in both the fixed-rate and variable-rate systems.