• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.4
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• pp.253-257
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• 2016

The effects of re-peening on the compressive residual stress and fatigue life of Al7075-T6 were investigated. The compressive residual stress induced on the surface of components by shot peening is known to increase the fatigue life. However, the fatigue load relaxes the compressive residual stress of components. Re-peening is a technique to again induce the relaxed compressive residual stress and increase the total fatigue life of components. In this study, the re-peening process was applied to fatigue-loaded specimens. The compressive residual stress and fatigue life were examined for re-peened specimens with fatigue ratios of 30%, 50%, and 70%. The results showed that the compressive residual stress of the specimens was relaxed under the fatigue load. The re-peening process significantly increases the compressive residual stress and total fatigue life.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.828-829
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• 2010

Rhenium-Iridium(Re-Ir) thin films were deposited onto the tungsten carbide(WC) molding core by sputtering system. The Re-Ir thin films on tungsten carbide molding core were analyzed by scanning electron microscope(SEM) and surface roughness. The Re-Ir coating technique has been intensive efforts in the field of coating process because the coating technique and process have been their feature, like hardness, high elasticity, adrasion resistance and mechanical stability and also have been applied widely the industrial and biomedical areas. In this report, tungsten carbide(WC) molding core was manufactures using high performance precision machining and the efforts of Re-Ir coating on the surface roughness.

• Journal of Environmental Impact Assessment
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• v.30 no.5
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• pp.328-338
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• 2021

EIA consultation is a final decision-making process that enables a variety of stakeholders to participate in and to share important information about the expected environmental impacts caused by development projects. However, this process is often undermined through re-consultation processes by significant changes in the proposed plans. EIA re-consultation is a necessary process when an approved plan needs to be changed for a variety of importantreasons including the changes of land use, delay of construction, and surrounding environments. EIA re-consultation is also important to resolve conflicts among stakeholders and to respond flexibly to unexpected changes in surrounding environment. This study aims to analyze the operation status and the problems of current institutional systems of EIA re-consultation, and to draw implications by reviewing institutional systems of other countries such as U.S. EU, Scotland, and Japan. On the basis of the previous analysis, we propose recommendations to improve the existing EIA re-consultation process. We expect this study helps understand operation status and problems of EIA re-consultation, and provides meaningful implications to improve the existing institutional systems and practice of re-consultation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.403-404
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• 2009

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.126-127
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• 2006

In this study, nano grain W is fabricated by Severe Plastic Deformation-Powder Metallurgy (SPD-PM) process. W powder and W-Re powder mixtures are processed by SPD-PM process, a Mechanical Milling (MM) process. As results, a nano grain structure, whose grain size is approximately 20nm, is obtained in W powder after MM for 360ks. A nano grain W compact, whose grain size 630nm, has excellent deformability above 1273K. A nano grain W-10Re compact is composed of equiaxed grain, a grain growth is restrained and has low dislocation density after the large deformation; therefore it is considered that W-Re compact shows superplasticity.

• International Journal of Aerospace System Engineering
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• v.5 no.2
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• pp.8-15
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• 2018

For small earth observation satellites, alignment between the optical components is important for precise observation. However, satellite cameras are structurally subject to misalignment in the launch environment where vibration excitations and impacts apply, and in space environments where zero gravity, vacuum, radiant heat and degassing occur. All of these variables can cause misalignment among the optical components. The misalignment among optical components results in degradation of image quality, and a re-alignment process is needed to compensate for the misalignment. This process of re-alignment between optical components is referred to as a refocusing process. In this paper, we proposed a 3 - axis focusing mechanism to perform the refocusing process. This mechanism is attached to the back of the secondary mirror and consists of three piezoelectric inertia-friction actuators to compensate the x-axis, y-axis tilt, and de-space through three-axis motion. The fabricated focus mechanism demonstrated excellent servo performance by experimenting with PD servo control.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.574-575
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• 2021

Re-manufacturing is the process of recovering the function and performance of the original product through a re-assembly process such as a new product assembly process after reprocessing by recovering used products or parts that are in the disposal stage at the end of their lifespan. One of the manufacturing methods. The remanufacturing industry is important not only in terms of environmental protection, but also in terms of economics. The success or failure of the industry as a whole depends on trust in products and price competitiveness. Image processing systems are used to reduce labor costs and improve product reliability in the product manufacturing process. In this study, foreign substances and defects that are difficult to identify with the human eye are detected by using the pre-processing step of determining whether to recycle the drum and image processing immediately before shipment after regenerating the drum to regenerate the waste drum.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.11
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• pp.951-959
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• 2016

The aim of this paper is to investigate the improvement of surface characteristics of Stellite21 deposited layer by powder feeding type of direct energy deposition (DED) process using a plasma electron beam. Re-melting experiments of the deposited specimen is performed using a three-dimensional finishing system with a plasma electron beam. The acceleration voltage and the travel speed of the electron beam are chosen as process parameters. The effects of the process parameters on the surface roughness and the hardness of the re-melted region are examined. The formation of the re-melted region is observed using an optical microscope. Results of these experiments revealed that the re-melting process using a plasma electron beam can greatly improve the surface qualities of the Stellite21 deposited layer by the DED process.

• Korean Journal of Materials Research
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• v.23 no.10
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• pp.543-549
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• 2013

The purpose of this paper was to investigate the effect of a high-energy milling (HEM) process on the particle morphology and the correlation between a thermal treatment and tetragonal/monoclinic nanostructured zirconia powders obtained by a precipitation process. To eliminate chloride residue ions from hydrous zirconia, a modified washing method was used. It was found that the used washing method was effective in removing the chloride from the precipitated gel. In order to investigate the effect of a pre-milling process on the particle morphology of the precipitate, dried $Zr(OH)_4$ was milled using a HEM machine with distilled water. The particle size of the $Zr(OH)_4$ powder exposed to HEM reduced to 100~150 nm, whereas that of fresh $Zr(OH)_4$ powder without a pre-milling process had a large and irregular size of 100 nm~1.5 ${\mu}m$. Additionally, modified heat treatment process was proposed to achieve nano-sized zirconia having a pure monoclinic phase. It was evident that two-step calcining process was effective in perfectly eliminating the tetragonal phase, having a small average particle of ~100 nm with good uniformity compared to the sample calcined by a single-step process, showing a large average particle size of ~300 nm with an irregular particle shape and a broad particle size distribution. The modified method is considered to be a promising process for nano-sized zirconia having a fully monoclinic phase.

• Journal of the Korea Institute of Building Construction
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• v.18 no.1
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• pp.67-79
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• 2018

This paper provides theoretical deformation of lean concept and its application for usage of building information modeling (BIM) process. Recently, much research is focused on application of lean concept for more efficient usage of BIM. The lean theory and its basic function and feature is based on manufacturing industry. The manufacturing process can be improved by process re-engineering steps of lean concept which consist of the steps of value, value stream, flow, pull, perfection. However manufacturing process and construction process has different characteristics. Due to the differences, five steps of the traditional lean's process re-engineering can't be directly applied to the BIM based engineering process. In order to solve this problem, we conduct analysis on the characteristics of the manufacturing process and BIM based engineering. We propose modified and expanded concept of lean for process re-engineering and the modified theory was applied to the mechanical, electrical and plumbing (MEP) coordination process. Through the proposed 8 steps of methodology, 2D based process was changed to integrated and using BIM based MEP coordination process. In addition, the results showed the potentiality of cost reduction and process improvement. The results of this study can be a foundation for the theoretical combination of lean and a variety part of construction engineering process.