• Journal of Navigation and Port Research
• /
• v.36 no.3
• /
• pp.225-232
• /
• 2012

In this research, the influence of additional vertical deformation of floating pontoon when dead load of each story is loaded during construction was investigated. The analysis procedure is presented for considering the influence of the additional deformation to calculate the additional moment of super-frame. Following the procedure, an example building with 3 storied steel frame was analyzed. Analysis method that taking no account for deformation of pontoon to the modeling was underestimated by ignoring design load following deformation of vertical load. By operating the load at the same time, design load under the influence of large deflection of model which whole modeling of floating structure was overestimated. So analysis method of floating structure considering the construction sequences demonstrated the suitable method.

• Steel and Composite Structures
• /
• v.44 no.3
• /
• pp.371-388
• /
• 2022

The present study tackles the problem of forced vibration of imperfect axially functionally graded shell structure with truncated conical geometry. The linear and nonlinear large-deflection of the structure are considered in the mathematical formulation using von-Kármán models. Modified coupled stress method and principle of minimum virtual work are employed in the modeling to obtain the final governing equations. In addition, formulations of classical elasticity theory are also presented. Different functions, including the linear, convex, and exponential cross-section shapes, are considered in the grading material modeling along the thickness direction. The grading properties of the material are a direct result of the porosity change in the thickness direction. Vibration responses of the structure are calculated using the semi-analytical method of a couple of homotopy perturbation methods (HPM) and the generalized differential quadrature method (GDQM). Contradicting effects of small-scale, porosity, and volume fraction parameters on the nonlinear amplitude, frequency ratio, dynamic deflection, resonance frequency, and natural frequency are observed for shell structure under various boundary conditions.

• Advances in concrete construction
• /
• v.15 no.3
• /
• pp.161-170
• /
• 2023

Ultra-high-performance concrete (UHPC) is produced using high amount of cementitious materials, very low water/cementitious materials ratio, fine-sized fillers, and steel fibers. Due to the dense microstructure of UHPC, it possesses very high strength, elasticity, and durability. Besides that, the UHPC exhibits high ductility and fracture toughness due to presence of fibers in its matrix. While the high ductility of UHPC allows it to undergo high strain/deflection before failure, the high fracture toughness of UHPC greatly enhances its capacity to absorb impact energy without allowing the formation of severe cracking or penetration by the impactor. These advantages with UHPC make it a suitable material for construction of the structural members subjected to special loading conditions. In this research work, the UHPC mixtures having three different dosages of steel fibers (2%, 4% and 6% by weight corresponding to 0.67%, 1.33% and 2% by volume) were characterized in terms of their mechanical properties including facture toughness, before using these concrete mixtures for casting the slab specimens, which were tested under high-energy impact loading with the help of a drop-weight impact test setup. The effect of fiber content on the impact energy absorption capacity and central deflection of the slab specimens were investigated and the equations correlating fiber content with the energy absorption capacity and central deflection were obtained with high degrees of fit. Finite element modeling (FEM) was performed to simulate the behavior of the slabs under impact loading. The FEM results were found to be in good agreement with their corresponding experimentally generated results.

• Journal of the Korean Magnetics Society
• /
• v.18 no.2
• /
• pp.71-74
• /
• 2008

In this paper, we have measured the effect of the optical spot size, incident upon the quadrant photodetector, on the optical displacement sensitivity of the optical beam deflection technique. We have built an optical displacement detection system based on the optical beam deflection method using 3 mW He-Ne laser and measured the displacement sensitivity with changing the optical spot size on the quadrant photodetector. We have also calculated the changes in the optical displacement sensitivity as a function of the incident laser spot size by modeling a circular optical spot with constant laser intensity. Our experimental and theoretical studies show that the optical displacement sensitivity increases with the decrease in the optical spot size. This suggests that in the design of the optical motion detection systems with sub-nanometer sensitivity, the displacement sensitivity can be optimized by reducing the size of the incident optical spot on the detector.

• Journal of the Society of Naval Architects of Korea
• /
• v.33 no.3
• /
• pp.103-111
• /
• 1996

A generalized slope deflection method has already been developed by the authors from the existing one, and applied to the 3-dimensional structural analysis of tankers idealized as frame models to verify the effectiveness of the method from the analysis viewpoint. In this study, a minimum hull weight design program of tankers is developed to verify the effectiveness of the method from the design viewpoint by the combination of generalized slope deflection method and optimization method considering discrete design variables. By this program, it is possible to determine the scantling of each member of actual tankers that give minimum weight under given constraints. Also, a considerable weight saving has been found compared with existing ship.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.12 no.1
• /
• pp.8-17
• /
• 2009

This paper proposes robust ship wake search method in the target evasion environment. Moving surface ships generate a long trailing wake in the rear of a surface ship. Wake homing torpedo sensing this wake can detect the surface target and engage it automatically. In wake homing torpedo, wake search method is important element to maximize effectiveness of wake homing torpedo. This paper proposes one-side, two-side and centering mode according to passing wake boundary scenarios. Also, wake deflection angle is deduced by using the principle of deflection angle of acoustic torpedo. The representative experimental results using monte-carlo simulation demonstrate that the searching method using one-side mode is superior to two-side and centering mode in the target evasion environment.

• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.9
• /
• pp.119-129
• /
• 2007

The residual life expectancy of the container crane which has been operated more or less 39 years is examined carefully, especially on the boom structure. The basic load and load combination need to be considered for to analyse the boom structure. Various parts of container crane are modeled for to analyse stress, the deflection and the fatigue. Analysis results show that the boom is stable in the stress and deflection but the boom vertical member is over the fatigue life. The rail support beam and boom bottom chord are approximately near the fatigue life. Analysis results show that the residual life of rail support beam and the boom bottom chord would be 2.2 years and 6.8 years, respectively.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.12 no.2
• /
• pp.206-214
• /
• 1988

To improve the surface waviness in the peripheral milling, the feedrate is controlled so that the cutting force measured in the normal direction to the workpiece is constant. A discrete time first order model between the feedrate and the tool deflection is derived for the control. It has been shown by the analysis that the tool deflection is directly related to the feedrate and largely affects the surface waviness during cutting. The experimental results shown that the surface waviness is drastically improved by the proposed methods.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.4
• /
• pp.173-180
• /
• 2000

In the process of grinding a long slender type workpiece, such as ballscrew, by the external cylindrical grinding machine, the cylindricity of the workpiece depends on the distance of rests, the stiffness of supports, the diameter and material of workpiece. Conventionally the process needs to be supported by one or more rests to prevent static deflection and vibration. In this paper, the optimal position of the rests was investigated in order to minimize the cylindricity due to the static deflection, by taking compliance of the workpiece and structure into account. In order to obtain the optimal position of rests, a new modeling that is considering the spring effect of all support elements was established. Since it is so complicated to obtain the optimal position analytically for various conditions due to discontinuity, a genetic algorithm u as utilized.

• Journal of the Korea Concrete Institute
• /
• v.11 no.5
• /
• pp.131-137
• /
• 1999

The use of higher strength materials with the strength methed of design has resulted in more slender member and shallower sections. For this reason, it is necessary to satisfy the requirements of serviceability even though the structural safety is the most important limit state. This paper is only concerned with the control of deflections in the serviceability. In this study, an analytical model is presented to predict the deflections of reinforced concrete beams to given loading and environmental conditions. This model is based on the finite element approach in which a finite element is generally divided into a number of stiffening effect due to cracking, creep and shrinkage. Comparisons are made with available measured deflections reported by others to assess the capability of the layered beam model. The calculated values of instantaneous and long-term deflection show good agreement with experimental results in the range of tension stiffening parameter $\beta$ between 2.5 and 3.0.