• Composites Research
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• v.29 no.6
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• pp.353-357
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• 2016

An appropriate way to fabricate a hybrid composite containing evenly dispersed carbon nano tubes(CNTs) is to stacking B-stage resin films that contain evenly dispersed CNTs and various reinforcing fiber layers alternatively. In the present study, B-stage resin films are manufactured via shear mixing and three-roll milling. CNT dispersion in resin via these two processes are evaluated by SEM on their fracture surfaces. For more efficient process, the dispersivities are evaluated according to the number of calendering passes. Samples are made for different number of passes during calendering, and their dispersions are evaluated via SEM fractographs as well as by measuring their electrical conductivities. Additionally, the optimal process conditions are obtained by measuring the electrical conductivity and evaluating their dispersivity of the samples prepared by gap mode and force mode.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.3
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• pp.663-670
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• 2015

In most public transportation related master plans, decisions for investment priorities are initially made by facilities with lower installation rates or lower satisfaction (performance) levels. In general, the decisions are made without conducting importance factor analysis. In this study, a combined method of importance-performance analysis (IPA) model for bus users related in travel time is proposed by using Structural Equation Model (SEM). The results of the IPA for Metropolitan users show that the categories need improvement are number of bus stops, number of intersections, headways, waiting times for boarding and traffic signal operations in order. On the other hand, Non-Metropolitan uses show that the categories need improvement are traffic signal operations, waiting times for boarding, headways, bus exclusive lanes and number of intersections that is in reverse order to Metropolitan users.

• Journal of the Korean GEO-environmental Society
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• v.13 no.4
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• pp.53-59
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• 2012

In this study, strength and durability of a geo-polymer grout material(HIT) was investigated through unconfined compression strength tests(UCS)), scanning electron microscope(SEM), elution tests, and surface observations. UCS tests showed high initial strength and rapid continuous strength increments when compared to labile wasser glass(LW) and space grouting rocket system (SGR) grout materials, which showed strength reduction after 28 days. The higher strength was also reflected in SEM results which showed calcium silicate hydroxide(C-S-H) gels of the dense hydrate range, indicating higher strength and durability. Additionally, elution tests and grout surface observations showed HIT was in good condition and the decrease in weight was minor when under water for six months. LW and SGR showed the grout surface to be constricted and lower durability due to higher weight increase. These results and observations show HIT to be better suited for coastal structural applications than LW and SGR in long terms of strength and durability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1803-1811
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• 2011

We have analyzed the electrical defect detection mechanism using low energy microcolumn on the TFT substrate for TFT-LCD. In this study, we have acquired the SEM images of the various pixel defects for 7-inch TFT substrate by scanning of low energy electron beam in the high vacuum chamber. Futhermore, we have interpreted the defect detection mechanism through the correlations between the SEM images and electrical behaviors of the defective pixels. As a result, we obtained consistent results as the follows. We can confirm that the SEM images using low energy electron beam are significantly affected by the space charge effect.

• Journal of Soil and Groundwater Environment
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• v.27 no.spc
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• pp.1-18
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• 2022

A conceptual site model is used to support decision-making of response strategy development, determination, and implementation within a risk-based contaminated site management system. It aims to provide base information of the relevant site characteristics and surface/subsurface conditions in order to understand the contaminants of concern and the associated risk they pose to the receptors. This study delineated the technical details of conceptual site model development, and discussed the possibility of applying it in domestic subsurface contamination management. Conceptual site models can be developed in various formats such as tables, diagrams, flowcharts, and figures. Contaminated sites are managed for a long period of time following the steps of investigation, remediation design, remediation, verification, and post-remedation management. The conceptual site model can be enhanced in each stage of the contaminated site management based on the continuously updated information on the site's subsurface environment. In the process of enhancement for conceptual site model, precision is gradually improved, and it can evolve from a conceptual and qualitative form to a more quantitatvive and three-dimensional model. In soil pollution management, it is desirable to incorporate the conceptual site model into the soil scrutiny system to better assess the current status of the contaminated site and support follow-up investigation and management.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.E
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• pp.29-38
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• 2000

For the detailed characterization of atmospheric aerosol, the analysis of single particle is highly valuable. In this study, to investigate the characteristics of single Asian dust storm particles, scanning electron microscope(SEM) coupled with and energy dispersive X-ray microanalyzer(EDX) and micro-PIXE were applied. Sampling was performed at Kyoto University located in Kyoto, Japan, in spring of 1999. Mass concentration during Asian dust storm events was higher roughly 3∼5 times than measured in the season of the highest concentration. Single particles were generally sharp-edged and irregular in shape and contained mostly crustal elements. Significant amount of S in coarse fraction was detected in individual particles. A large particles in coarse fraction existed as the mixture of soil components and S. A good agreement between the result of SEM-EDX analysis and that iof micro-PIXE analysis was obtained in this study.

• Journal of Digital Convergence
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• v.10 no.10
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• pp.75-83
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• 2012

The aim of this study is to test the behavioral acceptance of adopting smart-media for special education teachers on the points of personal innovativeness and social influence with structural equation modeling(SEM). The corelation of factors such as personal innovativeness, social influence, performance expectancy and behavioral intention are significant. The results of SEM analysis show that the direct impact of social influence on performance expectancy and behavioral intention is significant. The indirect impact of social influence toward behavioral intention through performance expectancy is also significant. However, the personal innovativeness is not statistically significant factor affecting performance expectancy and behavioral intention.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.5
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• pp.405-410
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• 2020

In this study, the following results were obtained by analysis of electric properties with FT-IR, DSC, XRD, and SEM, in the range of temperature 30~160℃ and frequency 0.1~200 kHz, when filling agent (0~100 phr) and silicone oil (0~12 phr) were added to raw silicone rubber. In the case of 100 phr mixed samples, the relative dielectric constant εr gradually decreased from 4.3 to 3.96 as frequency increased, and the dielectric loss tan δ decreased to 0.01 at 300 Hz, then increased to 0.022 at 30 kHz, then decreased to 200 kHz. The FT-IR analysis identified the same binding structure according to the chemical composition of added silica (SiO₂). Through DSC analysis, we could determine the change of heat quantity and the glass transition temperature of each specimen. In the XRD analysis, it was found that the images SiO₂, TiO₂, and Fe₂O₃ appeared for specimens with 0%, 50% and 100% filling agent. Finally, the SEM analysis confirmed that particles of 0.5 to 1.5 ㎛ size with silica (SiO₂) mixing were dispersed evenly.

• Analytical Science and Technology
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• v.13 no.3
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• pp.332-337
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• 2000

The study on the nitrogen adsorption, surface properties and water adsorption capacity of the carbonaceous desiccants derived from phenolic resin was carried out. In the nitrogen adsorption study on the carbonaceous desiccants, Type II isotherm for each sample was obtained. Furthermore, the adsorbed volume decrease with water washing of the desiccant. The $S_{BET}$ of the carbonaceous desiccants was $648.7m^2/g$ before washing and $189.3m^2/g$ after washing, respectively. The morphology of needlelike formation before washing and spherical particle after washing with water were observed from SEM micrographs. Finally, from the water adsorption effects, the percentage of the water loading capacity was 25-63%, and the capacity was good at relatively low humidity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.4
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• pp.545-549
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• 2006

W-EDM is generally used to manufacture punches and die plates from among press mold parts. Before W-EDM was used, however, punches and die plates manufactured via mechanical processing were used to manufacture products, with the die life of the mold expiring after 2,000,000~2,300,000 products have been manufactured. When the mold manufactured through W-EDM was used, however, its service life expired only after 700,000~800,000 products have been manufactured. Since this was attributed to the deformed layer formed after using W-EDM, the surfaces before and after W-EDM was used were scanned using SEM to verify the occurrence of such layer. This study sought to come up with a method of eliminating such phenomenon.