• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.42-45
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• 2003

The purpose of this study is the development or the extensive Rapid Prototyping Technique. which can resolve the long-term manufacturing process, shrinkage and deformation occurring rapid prototyping technique. To begin with. the various specimens for tensile were manufactured on the basis of this modeling technology. Then, many kinds of the laminate pieces for the test were made by using the sheet metals lmm and 1.5mm thickness which is composed of the same ingredient. The tensile specimen were manufactured by changing the process variables, Such as electric current, pressure and resistance welding time for the Rapid Prototyping with metal sheet. And then by using the Taguchi method. The interrelation between the specimen and mechanical properties were determined and the system for the optimum process variable organized.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.223-228
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• 2003

In end milling processes, characterized by use of rotating tools, the underformed chip thickness varies periodically with the phase change of tool. In current study, as a new approach to analyse shear behaviors In the shear plane and chip-tool friction behavior chip-tool contact region during an end milling process. In this approach, an up-end milling process is transformed into an equivalent oblique cutting process. Experimental investigations for two sets of cutting tests i.e.. up-end milling and the equivalent oblique cutting test were performed to verify the presented model.

• 한국생산제조학회지
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• 제24권2호
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• pp.211-216
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• 2015

Recently, because of the growth in the leisure industry and interest in health, the demand for bicycles has increased. In this research, considering the vertical load on a bike frame under static state conditions, the deflection and mass of the bike frame were minimized by satisfying the service condition and performing optimization. The thickness of the bicycle-frame tube was set to a design variable, and its sensitivity was confirmed by an analysis of means (ANOM). To optimize the solution, a response-surface-method (RSM) model was constructed using D-Optimal and central composite design(CCD). The optimization was performed using a non-dominant sorting genetic algorithm (NSGA-II), and the optimal solution was verified by finite-element analysis.

• Structural Engineering and Mechanics
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• 제6권8호
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• pp.883-899
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• 1998

The strength, deformation and buckling of a large engineering structure consisting of four ellipsoidal shells, two cylindrical shells with stiffening ribs and large holes, one conical shell and three pairs of large flanges under external pressure, self weight and heat sinks have been analysed by using two kinds of five different finite elements - four assumed displacement finite elements (shell element with curved surfaces, axisymmetric conical shell element with variable thickness, three dimensional eccentric beam element, axisymmetric solid revolutionary element) and an assumed stress hybrid element (a 3-dimensional special element developed by authors). The compatibility between different elements is enforced. The strength analyses of the top cover and the main vessel are described in the paper.

• Structural Engineering and Mechanics
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• 제9권2호
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• pp.169-180
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• 2000

An optimization procedure has been prescribed for the minimum weight design of symmetrical parabolic arches subjected to arbitrary loading. The cross section is assumed to be a symmetrical box section with variable depth and flange areas. The webs are unstiffened and have constant thickness. The proposed sequential, iterative search technique determines the optimum geometrical configuration of the parabolic arch which includes the optimum depth profile and the optimum lengths and areas of the required flange plates corresponding to the prescribed number of curtailments. The study shows that the optimum value of rise to span ratio (h/L) of a parabolic arch is maximum at 0.41 for uniformly distributed loading over the entire span. For any other loading, the optimum value of h/L is less than 0.41.

• Structural Engineering and Mechanics
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• 제57권3호
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• pp.441-456
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• 2016

This work reports wave propagation in the nanocomposite cylinders that reinforced by straight single-walled carbon nanotubes based on a mesh-free method. Moving least square shape functions have been used for approximation of displacement field in weak form of motion equation. The straight carbon nanotubes (CNTs) are assumed to be oriented in specific or random directions or locally aggregated into some clusters. In this simulation, an axisymmetric model is used and also the volume fractions of the CNTs and clusters are assumed to be functionally graded along the thickness. So, material properties of the carbon nanotube reinforced composite cylinders are variable and estimated based on the Eshelby-Mori-Tanaka approach. The effects of orientation, aggregation and volume fractions of the functionally graded clusters and CNTs on dynamic behavior of nanocomposite cylinders are studied. This study results show that orientation and aggregation of CNTs have significant effects on the effective stiffness and dynamic behaviors.

• 복식문화연구
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• 제2권2호
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• pp.385-394
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• 1994

Data of the body surface is a necessary unit for the measuring of metabolism energy and activity energy. And also, these data are referring to check the degree of retaining warmth of clothes, to find the effect of heat insulation according to body surface, to calculate an average temperature of skin, and to study the several fields of clothing. In measuring of body surface, it si actually impossible to measure a subject's body surface in each experiment. As the experimental method, both gypsum method, by which the shape of body an be copied as it is, and the weighting method from which planed body surface area can be measured with consistent thickness of polyprophylene film as used. In fact, every female subject feels uncomfortable to measure her body surface as a naked body. There, it is providing a simple, accurate regressive equation with weight & height as variable factors in this study. This equation is as=117.02W+77.31H-3344.94 with average error : 0.1%, absolute average error : 2.07%.

• 태양에너지
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• 제18권1호
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• pp.35-43
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• 1998

In two terminals monolithic tandem solar cells, tunnel diode is an important variable to improve conversion efficiency depending on current matching between the top and the bottom cells. Especially, the GaAs/Ge tandem is one of the most interesting cells for its high potential efficiency. This paper shows that physical analysis about I-V specific character of the GaAs/Ge solar cell, which is grown by MOCVD for GaAs or CVD for Ge, using computer simulation and experimental results, varying with thickness of the tunnel diode layer and concentration.

• Structural Engineering and Mechanics
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• 제67권3호
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• pp.291-300
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• 2018

In this work, a new trigonometry theory of shear deformation is developed for the static analysis of thick isotropic beams. The number of variables used in this theory is identical to that required in the theory of Euler-Bernoulli, sine function is used in the displacement field in terms of the coordinates of the thickness to represent the effects of shear deformation. The advantage of this theory is that shear stresses can be obtained directly from the relationships constitute, while respecting the boundary conditions at the free surface level of the beam. Therefore, this theory avoids the use of shear correction coefficients. The differential equilibrium equations are obtained using the principle of virtual works. A thick isotropic beam is considered, whose numerical study to show the effectiveness of this theory.

• 대한기계학회논문집B
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• 제32권4호
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• pp.317-326
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• 2008

The main purpose of the present study is to perform shape optimizations of transonic compressor blade in order to enhance its performance. In this study, the Latin hypercube sampling of design of experiments and the weighted average surrogate model with the help of a gradient based optimization algorithm are used within design space by the lower and upper limits of each design variable and for finding optimum designs, respectively. 3-D Reynolds-averaged Navier-Stokes solver is used to evaluate the objective functions of adiabatic efficiency and pressure ratio. Six variables from lean and airfoil thickness profile are selected as design variables. The results show that the adiabatic efficiency is enhanced by 1.43% by efficiency optimization while the pressure ratio is increased very small, and pressure ratio is increased by 0.24% by pressure ratio optimization.