• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.225-227
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• 2004

Recrystallization textures of ferritic stainless steel sheets of STS 430 were varied by means of different cold rolling procedures. The conventional normal rolling led to the evolution of strong through-thickness texture gradients in the final recrystallization texture, while the cross-rolling led to a decrease in texture gradients. Micro-texture observation by EBSD revealed that the formation of band-like orientation colonies formed close to the center layer was responsible for ridging. Modification of the recrystallization texture and microstructure by cross-rolling destroyed band-like orientation colonies and consequently reduced the ridging height.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.1
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• pp.34-38
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• 2008

The surface texture of a product is generally produced by etching or sandblasting. However, these techniques have problems related to repeatability and environmental pollution. Since current milling machines can produce small parts at the micrometer or nanometer level, the resolution of milling exceeds the manufactured dimensions of the surface texture produced by etching or sand-blasting. A method for generating surface texture by milling is proposed and demonstrated. The proposed method was demonstrated by actual milling using a three- or five-axis control machine, and the machined surface texture was measured with an interferometer to allow comparison with the designed shape. The measurement results demonstrate that the proposed method can generate a wide-area surface texture with good machining repeatability.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.519-520
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• 2013

• Journal of ILASS-Korea
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• v.17 no.1
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• pp.14-19
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• 2012

The present study conducts experimental investigation on spreading and deposition characteristics of a $4.3{\mu}l$ de-ionized (DI) water droplet impacting upon aluminum (Al 6061) flat and textured surfaces. The micro-textured surface consisted the micro-hole arrays (hole diameter: $125{\mu}m$, hole depth: $125{\mu}m$) fabricated by the conventional micro-computer numerical control (${\mu}$-CNC) milling machine process. We examined the surface effect of texture area fraction ${\varphi}_s$ ranging from 0 to 0.57 and impact velocity of droplet ranging from 0.40 m/s to 1.45 m/s on spreading and deposition characteristics from captured images. We used a high-speed camera to capture sequential images for investigate spreading characteristics and the image sensor to capture image of final equilibrium deposition droplet for analyze spreading diameter and contact angle. We found that the deposition droplet on textured surfaces have different wetting states. When the impact velocity is low, the non-wetting state partially exists, whereas over 0.64 m/s of impact velocity, totally wetting state is more prominent due to the increase kinetic energy of impinging droplet.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.5
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• pp.389-394
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• 2014

In this paper, we report a new manufacturing method for friction reduction using micro-AAJ (abrasive air-jet) machining. AAJ machining employs compressed air to accelerate a jet of high-speed particles to mechanically machine features, including micro-channels and micro-holes, into glass, metal, or polymer substrates for use in microfluidics, MEMS (micro electromechanical systems). And we introduce the micro-AAJ machining system, which consists of a micro-AAJ nozzle and a five-axis positioning system. Various micro-AAJ nozzles can be used, depending on the required surface structure, and three-dimensional machining is possible. We machined samples under six different conditions and describe machining results obtained while using it. We also measured the coefficient of friction of micro-textured surfaces. We report the coefficient of friction of micro-textured surfaces patterned using micro-AAJ machining for engine piston ring.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.4
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• pp.201-205
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• 2020

The structural texture is defined as a form which a texel is regularly repeated in the texture. Structural texture analysis/recognition has various industrial applications, such as automatic inspection of textiles, automatic testing of metal surfaces, and automatic analysis of micro images. In this paper, we propose a Convolution Neural Network (CNN) based system for structural texture analysis. The proposed method learns texles, which are components of textures to be classified. Then, this trained CNN recognizes a structural texture using a partial image obtained from input texture. The experiment shows the superiority of the proposed system.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.17-24
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• 2004

Surrface texturing of tribological application is another attractive technology of friction reducing. Also, reduction of friction is therefore considered to be a necessary requirement for improved efficiency of machine. In this paper attempts to investigate the effect of density for micro-scale dimple pattern using photolithography on bearing steel flat mated with pin-on-disk. We demonstrated the lubrication mechanism for a Stribeck curve, which has a relationship between the friction coefficient and a dimensionless parameter for lubrication condition. It is found that friction coefficient is depended on the density of surface pattern. It was thus verified that micro-scale dimple could affect the friction reduction considerably under mixed and hydrodynamic lubrication conditions from based on friction map. Lubrication condition regime has an influence on the friction coefficient induced the density of micro dimple.

• Transactions of Materials Processing
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• v.3 no.2
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• pp.229-242
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• 1994

An approximate procedure based on a combination micro-macroscopic theories of plasticity for predicting the crystallographic texture during the plane strain forming of fcc metals has been developed. This procedure is divided into two steps. Firstly, we extract the history of the deformation gradient at all deformed elements with a elasto-plastic finite element method using isotropic plasticity model. Secondly, we use this deformation gradient history to predict the crystallographic deformation texture based on the Bishop-Hill theory. Renouard and Wintenberger' method is chosen for selecting the active slip systems. The predicted results have been compared with reported experimental results. The calculated results are in good agreement with their results.

• The Korean Journal of Food And Nutrition
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• v.14 no.6
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• pp.596-604
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• 2001

Twelve varieties of Korean rice and ten varieties of Japanese rice were selected. After being milled. they were analyzed about various physicochemical properties such as moisture, protein and amylose, a -amylase activity, gelatinization properties. And after being cooked with proper amount of water texture and other physical properties were measured by Texturometer, Tensipresser and Rheolograph-micro. Finally the sensory evaluation test was carried out. The results were as follows. 1. In case of protein contents, amylose contents and $\alpha$-amylase activity, Korean rice had a slightly higher value than Japanese As a consequence. Korean rice showed a little stronger hardness and a little weaker stickiness compared with Japanese rice. 2. Amylose contents showed very high correlation with other physicochemical properties and peak viscosity and gelatinization temperature of RVA, the ratio of stickiness to hardness( -Hl/Hl ) of Texturometer and the tan $\delta$(the ratio of dynamic loss to dynamic viscoelasticity) of Rheolograph-micro showed high correlation with other analyzed properties. 3. The ( -/+)work balance of low compression test(25% ) of Tensipresser analysis(texture analysis on the surface of cooked rice) and tan f of Rheolograph-micro showed very high correlation with sensory evaluation results. By using this parameters as major independent variables, some trials to derive high confidence multiple regression equations were accomplished. By the equations it would be possible to make an approximate pre-estimate of eating quality for unknown japonica rice.

• 한국전자현미경학회:학술대회논문집
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• 2000.05a
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• pp.80-80
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• 2000