• Journal of the Korean Society of Safety
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• v.14 no.4
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• pp.53-59
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• 1999

Recently, Tailor Welded Blank (TWB) is widely used in automotive industry since the transformation characteristic of its material can be changed. However, clearance between welding surfaces becomes the important factor which affect the quality of the laser weld, causing difficulties in preparing the sheet. The objective of this paper is to systematically evaluate the effects of previously presented fracture criterion and shearing condition on precise mechanical shearing simulation result. For this purpose, a parametric study was peformed to investigate the effect of finite element size and fracture criterion on simulation result. Also, in order to predict the optimum shearing condition, effect of shearing conditions such as clearance and punch radius on the shear plane shape was evaluated.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.573-578
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• 2000

Recently, Tailor Welded Blanks(TWB) is widely used in automotive industry since the transformation characteristics of its material can be changed. However, clearance between welding surface becomes the important factor which affect the quality of the laser weld, causing difficulties in preparing the sheet. The objective of this paper is to systematically evaluate the effects of previously presented fracture criterion and shearing condition on precise mechanical shearing simulation result. Also predict the optimum shearing condition, effect of shearing condition such as clearance and punch radius on the shear plane shape was evaluated.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.5
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• pp.80-86
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• 2000

The Tailor Welded Blanks(TWB) are using various materials (different thickness, strength and different materials) can be welded together prior to the forming process. Therefore, TWB applications have become little by little important in automobile industries, because it has more light weight and process reduction. A burnish area is very important for TWB using laser welding. In this paper, evaluated failure criterion, effect of clearance and distance of between pad and punch by computer simulation. We used element separation method for fracture. And applied a plastic strain to failure criterion. According to the analysis results, we obtain failure criterion, when plastic strain is 2.0. The burnish area and clearance were inverse proportional.

• Current Optics and Photonics
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• v.7 no.6
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• pp.692-700
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• 2023

We present a method for improving the accuracy of the modal wavefront reconstruction in the radial shearing interferometers (RSIs). Our approach involves expanding the reduced radial terms of Zernike polynomials to high-order, which enables more precise reconstruction of the wavefront aberrations with high-spatial frequency. We expanded the reduced polynomials up to infinite order with symbolic variables of the radius, shearing amount, and transformation matrix elements. For the simulation of the modal wavefront reconstruction, we generated a target wavefront subsequently, magnified and measured wavefronts were generated. To validate the effectiveness of the high-order Zernike polynomials, we applied both low- and high-order polynomials to the wavefront reconstruction process. Consequently, the peak-to-valley (PV) and RMS errors notably decreased with values of 0.011λ and 0.001λ, respectively, as the order of the radial Zernike polynomial increased.

• Design & Manufacturing
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• v.8 no.1
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• pp.35-39
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• 2014

Window roller housings are durable because high-quality source materials such as stainless steel is used in making them. After a series of precise structure analysis, their design is optimized. They are subject to repetitive driving tests of more 100,000 times, durability tests, impact resistance tests, corrosion tests and others. For a long time, gaps often occur in press molded products owing to serious squareness deformation and flatness deformation of them. Severe burrs in press molded products require frequent grinding, which leads to short life cycle and rough or unreliable movement of assembled roller housing, which, in turn, causes product defects. This study focuses on developing measures to resolve existing defects and to improve lifespan of dies by designing and making a window roller shearing die.

• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1845-1852
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• 2001

This paper deals with the experiment to obtain quantitative information about conditions of the interface between a water drop and surrounding oil. Velocity distributions in very close region of the interface are measured by introducing a new illumination technique and a telecentric lens. It enables precise measurements of velocity distributions in the close region to the interface. Although the measured velocity distributions exhibit strong influence from the solid wall of an experimental tube, the coincidence of inner and outside velocities on the interface is clearly confirmed for the clean interface. The shearing stresses on the interface, which are proportional to the velocity gradient normal to the interface, clearly show conditions of contaminated interface, which can be divided into two parts. From front stagnation point to somewhere near a separation point, the distribution of shearing stresses is well coincide with that of the Hadamard's analytical solution, while the distribution on the latter part of the interface sows quite different feature, which is supposed to be strongly influenced by contamination of the surface.

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.5
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• pp.80-93
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• 2000

This study measured the shearing resistance of the roots of the Pinus Koraiensis by the tensile strength gained through their individual tensile test for the Root Reinforcement Model. On the basis of the shearing resistance value calculated through such a process the factor of safety(Fs) was comparatively presented by using the simplified Janbu Method in PCSTABL5M, the slop-analyzing software which had been developed in Purdue University of the U.S.A according to the shape of a slope and the type of soil. The results to have measured a stress and the factor of safety(Fs) by experiment are as follows. 1) The mean root diameter of the Pinus Koraiensis used for this experiment was 2.483mm and the mean tensile stress was calculated as 422.846(kgf/$\textrm{cm}^2$). In the strain ratio of material and the elastic modulus was measured 7.8%, 9,291.92(kgf/$\textrm{cm}^2$). 2) The shearing strength including the resistance of soil and root is expressed as Rt=C+Cr+$\sigma$.tan . ΔCr(kg/$\textrm{cm}^2$) of the shearing resistance calculated by estimating the areal ratio of roots at 10 is 0.253(kgf/$\textrm{cm}^2$). 3) As the result of making an analysis of the natural slope stability by the soil parameter, the factor of safety(Fs) was calculated at 1.795 in CL, and the stability analysis of the root reinforcement slope, Fs was calculated at 1.952. However, since a precise analysis of the controlled factors of the slope analyses are demanded for more accurate dynamic analyses, the future demands a study on this.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.1 no.1
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• pp.54-62
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• 1998

This study measured the shearing resistance of the roots of the Sasamorpha purpurascens, Miscanthus sinensis, Lespedeza cyrtobotrya by the tensile strength gained through their individual tensile test for the Root Reinforcement Model. The results to have measured this stress by experiment are as follows. 1) The mean root diameter of the Lespedeza cyrtobotrya used for this experiment was 2.19mm and the mean tensile stress was calculated as $929.489kgf/cm^2$. As for the Sasamorpha purpurascens, its mean root diameter was 1.727mm, and the mean tensile stress was $292.069kgf/cm^2$. And as for the Miscanthus sinensis, its mean root diameter was 0.814mm, and the mean tensile stress was $696.947kgf/cm^2$. And so, it was grasped that Lespedeza cyrtobotrya was highest in tensile stress. 2) ${\Delta}Cr(kg/cm^2)$ of the shearing resistance calculated by estimating the areal ratio of roots at $10^{-3}$ is $1.069kg/cm^2$ in Lespedeza cyrtobotrya, $0.336kg/cm^2$ in Sasamorpha purpurascens, and $0.801kg/cm^2$ in Miscanthus sinensis. That is, Lespedeza cyrtobotrya has the highest shearing resistance. However, since a precise analysis of the controlled factors of the slope analyses are demanded for more accurate dynamic analyses, the future demands a study on this.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1824-1827
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• 2003

The sheet metal shearing process is normally used in the precision elements such as semi-conductor components. In precision elements, burrs usually reduce the quality of machined parts and cause interference, jamming and misalignment during assembly procedures and because of their sharpness, they can be safety hazard to personnel. Furthermore, not only burrs are hard to predict and avoid, but also deburring, the process of removing burrs, is time-consuming and costly. In order to get the burr-free parts, therefore, we developed the precise burr measuring system using the laser. The laser burr measuring system consists of the laser probe, the photo detector, the achromatic doublet lens, and the rotary ＆ the X-Y table. In previous reports, we used simple vertical measuring method. But, as we used relatively bigger laser spot diameter and had the limited reflection angle, it was difficult to obtain the precise measuring results. So called, the spot size effect makes the profile of burr measured distorted and the burr height measured smaller. By introducing the novel laser measuring method which employing the achromatic lens system and the tilting mechanism, we could make the spot size smaller and get the appropriate beam direction angle. Through the experiments, the accuracy of the developed system is proved. The burr height measured during the punching process can be used for automatic deburring and in-situ aligning.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.633-638
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• 2012

The doctor blade is a core part of a laser printer and directly influences the printing quality. The main specifications for doctor blades ate for them to be precise and durable. It is necessary to study an automatic production system for doctor blades in order to obtain high-efficient manufacturing processes. In this paper, the technology and the design of the automatic production line has for manufacturing doctor blades has been researched. The automated manufacturing process consists of five steps, which are the supplying of raw material, shearing, bending, bracket supplying, and the laser-spot welding process. The proposed automatic manufacturing system allowed for faster and more reliable production of doctor blades.