• Korean Journal of Cognitive Science
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• v.23 no.1
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• pp.47-71
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• 2012

This study examined how students revised their writing after reciprocal peer review and how their revision activities were influenced by the review. Undergraduates in physics class wrote a laboratory reports, exchanged comments with peers, and revised their reports afterward based on the comments they received from their peers. The comparison between the original and the revised drafts showed that students were mainly concerned with micro-meaning revisions, focusing on making changes on individual words, clauses, and sentences. Revisions that dealt with macro-meaning of the texts were not as frequent. Giving and receiving comments influenced later revision activities. Receiving comments on micro-meaning of the texts led to a significant increase in both micro- and macro-meaning revisions. Receiving comments on macro-meaning of the texts, however, did not prompt relevant revision activities. Even when students engaged in macro revision, it was negatively related to writing performance gains in one subgroup, suggesting that even after peers point out macro-problems in their writing, students are not competent to solve the problems yet. The results of the study suggest that more efforts are needed to help them to understand and manipulate the macro-meaning structure of the texts.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.3
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• pp.159-165
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• 2021

This study introduces a topology optimization method for the simultaneous design of macro-scale structural configuration and unit structure variation to ensure effective heat conduction. Shape changes in the unit structure depending on its location within the macro-scale structure result in micro- as well as macro-scale design and enable better performance than using isotropic unit structures. They result in functionally graded composite structures combining both configurations. The representative volume element (RVE) method is applied to obtain various thermal conductivity properties of the multi-material based unit structure according to its shape change. Based on the RVE analysis results, the material properties of the unit structure having a certain shape can be derived using machine learning. Macro-scale topology optimization is performed using the traditional solid isotropic material with penalization method, while the unit structures composing the macro-structure can have various shapes to improve the heat conduction performance according to the simultaneous optimization process. Numerical examples of the thermal compliance minimization issue are provided to verify the effectiveness of the proposed method.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.161-167
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• 2014

This paper describes reinforcement method of reinforced earth wall near the abutment. The excessive displacement of a case affected by reduction of bearing capacity due to macro-environment condition like a coast. That is, the front displacement of reinforced earth wall has been happening continuously due to strength reduction of foundation ground. The micro pile is applied to reinforcement method, in order to secure a bearing capacity and global slope stability of reinforced earth wall. The results of numerical analysis confirmed that reinforcement method based on micro pile can secure a stability of structure, while the reconstruction of reinforced earth wall is impossible by construction and macro-environment condition.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.471-476
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• 2001

Milli-structure components ate classified as a component group whose size is between macro and micro scales, that is, about less than 20mm and larger than 1mm. The forming of these components has a typical phenomenon of bulk deformation with thin sheets because of the forming size. In this study, milli-structure rectangular cup drawing is analyzed and measured using the finite element method and experiment. Generally, milli-structure containers or cases like cellular phone vibrator consist of rectangular-shaped drawing to save installation space. A systematic approach is established for the design and the experiment of the forming processes for rectangular milli-structure cases. To verify the simulation results, the experimental investigations were also carried out on a real industrial product. The numerical analysis by FEM shows good agreement with the experimental results in view of the deformation shape of the product.

• Environmental Engineering Research
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• v.12 no.3
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• pp.109-117
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• 2007

The characteristics of carbonaceous particles collected from the combustion of Vacuum Residue (VR) in a test furnace have been investigated. The physical and chemical characterization includes particle size, scanning electron microscopy of the surface structure, measurement of porosity, surface area and density, EDX/XRD analyses and measurement of chemical composition. The studies show that the carbonaceous VR particles are very porous and spheroidal, and have many blow-holes on the surface. The particles become smaller and more sponge-like as the reaction proceeds. The present porosity of VR particles is similar to that of cenospheres from the combustion of heavy oil, and the majority of pores are distributed in macro-pores above $0.03\;{\mu}m$ in diameter. Measurements of pore distribution and surface area showed that the macro-pores contributed most to total pore volume, whereas the micro-pores contributed to total surface area.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.781-783
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• 1993

The GTO model is based on the Ebers-Moll equation extened to include the three-junction devices and a detailed description of the implementation of the model equation as well as defferent tests are discussed. Problems to be considered for the snubber design, such as voltage spike reduction, maximum GTO anode current, and switching power, were discussed using the calculation model. The macro model is very useful for simulation of GTO circuit and high power circuit switch in high frequency and complex structure.

• Journal of the Korean Ceramic Society
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• v.36 no.3
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• pp.260-265
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• 1999

보통 포틀랜드 시멘트와 플라이애쉬, 슬래그를 혼합한 혼합시멘트 경화체를 이용하여 이온 확산에 미치는 혼합재의 영향과 양이온 공존시 염소이온의 확산에 대하여 고찰하였다. 겉보기 이온확산계수가 보통 포틀랜드의 시멘트보다 플라이애쉬와 슬래그를 혼합한 시멘트 경화체가 약 10-3배로 매우 낮은 값을 나타내었다. 이것은 포졸란 반응에 의해 많은 CSH 수화물이 capillary pore에 형성되어 macro pore가 감소되고 micro pore가 증가되어 이온 확산에 대한 저항이 커졌기 때문이다. 또한, Mg2+이온 공존시에 염소이온의 확산은 증가되었다.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.195-197
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• 1993

In this paper, a planar vibratory gyroscope is designed and fabricated in macro model. Elementary experiment and test are done for micro model. This gyroscope has a double gimbal structure with an active dimension $80{\times}120{\times}1\;mm^3$. Outer gimbal vibration is generated by electromagnetic force using ferrite E-core wounded by coil. Inner gimbal vibration is detected by inductive sensor. It is demonstrated' that mechanical and electrical symmetries are important for improvement of vibratory gyroscope.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.235-238
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• 2001

Milli-structure components are classified as a component group whose size is between macro and micro scales, that is, about less than 20mm and larger than 1mm. The forming of these components has a typical phenomenon of bulk deformation with thin sheets because of the forming size. In this study, milli-structure rectangular cup drawing is analyzed and measured using the finite element method and experiment. Generally, milli-structure containers or cases like cellular phone vibrator consist of rectangular-shaped drawing to save installation space. A systematic approach is established for the design and the experiment of the forming processes for rectangular milli-structure cases. To verify the simulation results, the experimental investigations were also carried out on a real industrial product. The numerical analysis by FEM shows good agreement with the experimental results in view of the deformation shape of the product.

• Korean Journal of Materials Research
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• v.12 no.5
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• pp.398-406
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• 2002

VAR process is required to control its various operating parameters. Heat transfer simulation has been accomplished to understand development of solidification micro and macro-structures during VAR process in Ti alloys. Optimum VAR process parameters could be also estimated in this study. It was found that macro-structures were closely related to the shape and depth of liquid pool, and solidification parameters, such as temperature gradient, heat flux, solid fraction. The cooling rates were higher at bottom, top, and center part respectively. As cooling rates increased, the $\alpha$ phase decreased in length, width and fraction. In order to evaluate which parameter affects the result of heat transfer calculation most sensitively, the sensitivities of input parameters to the simulation result were examined. The pool depth and cooling rate showed more sensitive to the temperature of the molten metal, heat transfer coefficient, and liquidus respectively. Also, these thermal properties became more sensitive at higher temperatures.