• Journal of the Korea Concrete Institute
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• v.27 no.2
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• pp.169-176
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• 2015

Since the size effect law announced currently has been based on the normal weight concrete, for light weight concrete having different fracture characteristics, its application is questionable. Accordingly, in this study, a model equation to predict the effect of dried unit weight of the concrete on size effect of its compressive strength was developed and a database using existing research results was created. After determining the experimental constants of prediction models of Ba${\check{z}}$ant based on nonlinear fracture mechanics, Kim and Eo, and this study using the database, their results are mutually compared. Finally, it was found that the prediction model of this study considered dried unit weight of concrete predicted well the test results for light weight concrete than that of the models of Ba${\check{z}}$ant and Kim and Eo.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.7
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• pp.1711-1718
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• 2015

A Meta-analysis refers to a statistical literature synthesis method from the quantitative results of many known empirical studies. Recently, the convergence of knowledge-based society and, information telecommunication technologies has a rapid impact on politics, economics and various fields. A meta-analysis was conducted to identify the relationships among satisfaction, trust, and loyalty in e-commerce studies. A total of 57 research papers published in Korean academic journals during 2002 and 2013 were reviewed and the causal relationships among satisfaction, trust, and loyalty in e-commerce were established. The result of the meta-analysis might be summarized that the highest effect size (r =. 591) was in the path from the satisfaction to the trust. The second biggest effect size (r =. 554) was found in the path between the satisfaction to the loyalty. The third biggest effect size (r =. 552) was found in the path between the trust to the loyalty. By the way, the smallest effect size (r =. 484) was found in the path between the trust to the satisfaction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.2979-2984
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• 2015

This paper has presented a new foaming technology of selective hybrid-structured polymer film with expanded pores. The porous structure of closed pore was firstly fabricated by applying the 355nm UV-pulsed laser to 0.1mm thick film that was uniformly mixed with PP pellets, copper powder, and CBA (Chemical Blowing Agent). In order to expand pore size of closed-cell shape, LAMO(Laser Aided Micro pore Opening) processing was conducted to heat the copper powder, and then the bigger pore size of closed-cell more than existing pore size was successfully formed because of rapid conduction of heated metal powder. From the experimental results, various process parameters such as laser fluence, intensity, scan rate, spot size and density of powder and CBA were considerably considered to reveal the correlation among the pore characteristics. In the future, a function experiment will be carried out to use the hybrid film of industrial applications.

• Environmental Analysis Health and Toxicology
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• v.30
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• pp.3.1-3.6
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• 2015

Objectives This study aims to evaluate the size-dependent toxicity of spherical silver nanoparticles (Ag NPs) to an endemic benthic organism, Glyptotendipes tokunagai. Methods Ag nanoparticles of three nominal sizes (50, 100, and 150 nm) capped with polyvinyl pyrrolidone (PVP-Ag NPs) were used. Their physicochemical properties, acute toxicity (48 hours), and bioaccumulation were measured using third instar larvae of G. tokunagai. Results The aggregation and dissolution of PVP-Ag NPs increased with exposure time and concentration, respectively, particularly for 50 nm PVP-Ag NPs. However, the dissolved concentration of Ag ions was not significant compared with the median lethal concentration value for $AgNO_3$ (3.51 mg/L). The acute toxicity of PVP-Ag NPs was highest for the smallest particles (50 nm), whereas bioaccumulation was greatest for the largest particles (150 nm). However, larger PVP-Ag NPs were absorbed and excreted rapidly, resulting in shorter stays in G. tokunagai than the smaller ones. Conclusions The size of PVP-Ag NPs significantly affects their acute toxicity to G. tokunagai. In particular, smaller PVP-Ag NPs have a higher solubility and stay longer in the body of G. tokunagai, resulting in higher toxicity than larger PVP-Ag NPs.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.51.1-51.1
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• 2015

OLED commercialization has been led in mobile market by Samsung since 2007, but more suppliers in Korea, China and Japan are joining the market. However, there remain some challenges in expanding its application to large size TV and flexible displays, especially in competition with dominant LCD products. This talk will discuss future prospects of the OLED technology after brief review of the progress.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.8
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• pp.106-114
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• 2015

Nowadays, cameras embedded in smartphones can take high resolution photographs that can be used to analyze skin conditions without using specialized equipments. In shooting photographs with a smartphone, it is difficult to maintain a uniform shooting distance. Therefore, it is essential to adapt a skin analysis method to the shooting distance. In this paper, we focus on a pore detection algorithm that is adaptive to the camera distance. We develop a relationship model between the shooting distance and the appropriate size of the pore detection mask. In addition, we propose a method to estimate the normalized pore size (i. e. pore size at a standard shooting distance). We conducted experiments on skin images taken from different shooting distances. It was verified that the proposed method can achieve more accurate pore detection result, close to those from skin images taken at a standard shooting distance.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.22 no.3
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• pp.77-87
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• 2017

Picophytoplankton, an important primary producer especially at the oligotrophic region, is known to contribute a significant portion of the total phytoplankton biomass in the East Sea of Korea. During autumn in the southwestern East Sea, frequent upwellings and oligotrophic conditions occur and annual variation of primary productivity is known to be significant. Moreover sea surface temperature (SST) of the East Sea is steeply increasing compared to global average increase, so various changes in marine ecosystem related with increase of SST are reported. Taking such circumstances into consideration, we measured the contribution from picophytoplankton fraction to total phytoplankton composition by size fraction of phytoplankton biomass during the autumn seasons from 2011, 2013 and 2015 and examined the variation of the phytoplankton composition. As a result of size fraction analyses, we found that the variation of contribution from picophytoplankton(<$3{\mu}m$) to total community of phytoplankton was high and the average fractions of picophytoplankton were measured as 38% (2011), 59% (2013), 7% (2015), respectively. The difference between measured SST and annual mean SST (${\Delta}T$) was highest ($+1.6^{\circ}C$) in autumn of 2013 and lowest ($-0.9^{\circ}C$) in autumn of 2015. The close positive correlation between ${\Delta}SST$ and fraction of picophytoplankton was confirmed($R^2$ > 0.9). The increase in SST at the southern East Sea was confirmed as one of the main environmental factors in the increase in the increase of the contribution from picophytoplankton. Monitoring of changes in the community structure of primary producers and the influences of the environmental factors including SST in the East Sea is necessary to understand the interactions of ecosystem of the East Sea and the climate change in the near future.

• Resources Recycling
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• v.24 no.5
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• pp.3-14
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• 2015

This study investigated that status of domestic and international furnace desulfurization and desulfurization characteristics of limestone for fluidized bed use depending on the technology for CFBC one of the CCPs. Limestone-based desulfurizing agent is one of the superior elements which are optimal at around $850-950^{\circ}C$ on high temperature desulfurization. And effectiveness of desulfurization process can be determined by the desulfurization experiment method such as diffusion reaction of the diaphragm of the absorber surface, the size of the particles, the pores of the quantity, size and structure. And, desulfurization efficiency depending on geological and crystallographic properties and calcination process of limestone needs additional research in the future.

• Journal of Conservation Science
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• v.31 no.4
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• pp.331-339
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• 2015

This study were conducted the particle-size analysis on 57 blue pigments to understand the step distribution characteristics of blue pigments made out of Azurite by using Malvern's Mastersizer 2000. As the result, most of the conventional blue pigments in Korea, Japan, and Chinese showed good granularity step separation except for few, and the smaller the particle, the more the Span value increased and the wider the granularity distribution range. On the basis of Friedman and Sanders's Grain size, most of the pigments were sand size to silt size. 72.2% of B-100 was clay size and 2.5% of A-14 was gravel size. Even the same components can differ by the grain size directly affecting the important property such as color formation, oil absorption, specific gravity, usability, etc. so the information about the granularity distribution would be used for basic data to deal with natural pigments.

• Analytical Science and Technology
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• v.28 no.1
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• pp.33-39
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• 2015

CdS-QD particles are a nano-sized semiconducting crystal that emits light. Their optical properties show great potential in many areas of applications such as disease-diagnostic reagents, optical technologies, media industries and solar cells. The wavelength of emitting light depends on the particle size and thus the quality control of CdS-QD particle requires accurate determination of the size distribution. In this study, CdS-QD particles were synthesized by a simple ${\gamma}$-ray irradiation method. As a particle stabilizer polyvinyl pyrrolidone (PVP) were added. In order to determine the size and size distribution of the CdS-QD particles, sedimentation field-flow fractionation (SdFFF) was employed. Effects of carious parameters including the the flow rate, external field strength, and field programming conditions were investigated to optimize SdFFF for analysis of CdS-QD particles. The Transmission electron microscopy (TEM) analysis show the primary single particle size was ~4 nm, TEM images indicate that the primarty particles were aggregated to form secondary particles having the mean size of about 159 nm. As the concentration of the stabilizer increases, the particle size tends to decrease. Mean size determined by SdFFF, TEM, and dynamic light scattering (DLS) were 126, 159, and 152 nm, respectively. Results showed SdFFF may become a useful tool for determination of the size and its distribution of various types of inorganic particles.