• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.365-368
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• 2006

In this paper, the post cracking stress-crack width relationship of the composite is studied from a micromechanics points of view. Cook-Gordon debonding effect is studied by more refined method with considering of chemical friction of fiber interface. As a result, fiber with pre-debonding length retards stress development and shows more wide crack width for the same force level. longer pre-debonding length and lower pre-debonding bond strength results in lower full-debonding force, but same crack width.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.5
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• pp.442-449
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• 2013

In this paper, a simulation system based on X-Plane and MATLAB/Simulink for multiple UAVs is presented. For the conceptual design of this proposed system, a hierarchical system architecture for multiple UAVs is presented. This architecture has object-oriented data structure which consists of three objects (UAV status, mission and task, and environment) and a hierarchy consisting of four layers (decision making layer, task assignment layer, path and motion planning layer, and collision avoidance layer) is also proposed. In addition, this paper shows a implementation of simulation system based on the proposed system architecture using X-Plane and MATLAB/Simulink. The result of simulation from the developed system in this paper validate capability of application for multiple UAVs in real environment.

• Journal of the Society of Naval Architects of Korea
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• v.61 no.3
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• pp.200-207
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• 2024

A multi-component force sensor has been developed to measure force and moment components in high-speed flow media for submerged models. The size of the test model is determined based on the Reynolds number of the model at the test speed and expected blockage effect. A two-component force sensor unit has been created by assembling pairs of column elements arranged symmetrically under an eccentric load. The six-component force sensor is constructed with symmetric arrangements of two-component force sensor units in a rectangular plane. The signals generated from the strain gauges attached to the surface of the elements can be converted into force signals. The performance of the waterproof six-component force sensor has been evaluated through calibration. A simplified interference decomposition procedure has been introduced to increase the accuracy of measurement.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.10
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• pp.1092-1098
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• 2009

The squeal propensity of an automotive disc brake system is studied in the theoretical and computational manner. The rotating disc is in contact with two stationary pads and the nonlinear friction is engaged on the contact surface. The friction-coupled equations of motion are derived in the finite element(FE) of the actual brake disc and pad. From the general definition of friction force, the rotation and in-plane mode effects can be included properly in the brake squeal model. The eigenvalue sensitivity analysis and the mode shape visualization at squeal frequencies are also conducted for the detailed investigation. It is found that the squeal propensity is strongly influenced by rotation effect and the in-plane mode can be involved in squeal generation.

• Steel and Composite Structures
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• v.24 no.5
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• pp.523-536
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• 2017

A layerwise (LW) formulation based on the Galerkin method is presented to investigate the three-dimensional stress state in long sandwich plate which is subjected to tension force and pure bending moment. Based on the Galerkin method and the LW discretization approach, the equilibrium equations of elasticity for the long plate are written in the weak form and discretized through the thickness of the plate. The discretized equations are written in terms of displacement components of the numerical layers. The governing equations of the plate are solved analytically for the free edge boundary conditions. The distribution of stress state especially the 3D stress state in the vicinity of the edges of the sandwich plate which is subjected to tension and pure bending is studied. In order to increase the accuracy, the out of plane stresses are obtained by integrating the equilibrium equations of elasticity. The convergence and accuracy of the predictions are studied and various numerical results are presented for distribution of the in-plane and out of plane stresses in symmetric and un-symmetric sandwich plates.

• Journal of Dental Rehabilitation and Applied Science
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• v.20 no.2
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• pp.143-150
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• 2004

Endosseous implants have been used to provide anchorage control in orthodontic treatment without the need for special patient cooperation. However these implants have limitation like space requirement, cost, equipments. Recently titanium micro-implant for orthodontic anchorage was introduced. Micro-implants are small enough to place in any area of the alveolar bone, easy to implant and remove, and inexpensive. In addition, orthodontic force application can begin almost immediately after implantation. The mandibular first, maxillary first, mandibula second, and maxillary second molars were the four most commonly missing teeth in adult sample. In case of posterior molar teeth missing, deflective contacts in any position, over time, has produced pathologic change of occlusal scheme because of extrusion of opposing teeth. This case had interocclusal space deficiency by mandibular right molars missing over time. The micro-implants had been used for intrusion of maxillary right molars for interocclusal space. The micro-implant would be absolute anchorage for orthodontic movement. Therefore, the micro-implant would be effective method for correction of occlusal plane.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.173-178
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• 2003

Recently, according to the development of mechatronics industry that was composed of NT, ST, IT, RT and etc, the 1 necessity of nano-parts was increased. Because of the necessity, this research was started for improving work precision of the parts as fixing UPCU( Ultra Precision Cutting Unit)on lathe. So, in this research we executed the modeling of UPCU (Ultra Precision Cutting Unit) by the application of PZT, the relationship between the displacement of tool in UPCU and the cutting force of it has been in take a triangular position in the case of plane cutting. The modeling of system that is containing the fine displacement was performed. Also, we found like to find the optimal cutting condition through the simulation of relationship between the displacement and the cutting force.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.15 no.1
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• pp.18-27
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• 2019

The Advanced Power Reactor 1400 (APR1400) Steam Generator (SG) uses alloy 690 as a tube material and SA-508 Grade 3 Class 1 as a tubesheet material to form tube-to-tubesheet joint through hydraulic expansion process. In this paper, the residual stresses in the SG tube-to-tubesheet contact area was investigated by applying Model-Based System Engineering (MBSE) methodology and the V-model. The use of MBSE transform system description into diagrams which clearly describe the logical interaction between functions hence minimizes the risk of ambiguity. A theoretical and Finite Element Methodology (FEM) was used to assess and compare the residual stresses in the tube-to-tubesheet contact area. Additionally, the axial strength of the tube to tubesheet joint based on the pull-out force against the contact joint force was evaluated and recommended optimum autofrettage pressure to minimize residual stresses in the transition zone given. A single U-tube hole and tubesheet with ligament thickness was taken as a single cylinder and plane strain condition was assumed. An iterative method was used in FEM simulation to find the limit autofrettage pressure at which pull-out force and contact force are of the same magnitude. The joint contact force was estimated to be 20 times more than the pull-out force and the limit autofrettage pressure was estimated to be 141.85MPa.

• Steel and Composite Structures
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• v.17 no.1
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• pp.1-19
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• 2014

Buckling and vibration characteristics of circular laminated plates under in-plane edge loads and resting on Winkler-type foundation are solved by the Ritz method. Inclusive numerical data are presented for the first three eigen-frequencies as a function of in-plane load for different classical edge conditions. Moreover, the effects of fiber orientation on the natural frequencies and critical buckling loads of laminated angle-ply plates with stacking sequence of $[({\beta}/-{\beta}/{\beta}/-{\beta})]_s$, are studied. Also, selected deformation mode shapes are illustrated. The correctness of results is established using finite element software as well as by comparison with the existing results in the literature.

• Steel and Composite Structures
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• v.5 no.4
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• pp.305-326
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• 2005

The inelastic buckling behaviour of continuously restrained two and three-span continuous beams subjected to concentrated loads and uniformly distributed loads are studied in this paper. The restraint type considered in this paper is fully restrained against translation and elastic twist applied at the top flange. These types of restraints are most likely experienced in industrial structures, for example steel-concrete composite beams and half through girders. The buckling analysis of continuous beam consists of two parts, firstly the moment and shear distribution along the member are determined by employing force method and the information is then used for an out-of-plane buckling analysis. The finite element method is incorporated with so-called simplified and the polynomial pattern of residual stress. Owing to the inelastic response of the steel, both the in-plane and out-of-plane analysis, which is treated as being uncoupled, extend into the nonlinear range. This paper presents the results of inelastic lateral-torsional and lateral-distortional buckling load and finally conclusions are drawn regarding the web distortion.