• Journal of the Architectural Institute of Korea Structure & Construction
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• 제35권12호
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• pp.149-156
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• 2019

Recently, skyscraper building and apartment fires, which were rapidly spread out from a low floor to a rooftop, have become a frequent occurrence in mass media. This fire problems have a fatal disadvantage that the exterior wall finish of the building emits toxic gas in case of fire by using dry bit method or organic insulating material. Therefore, in order to remedy these problems, many exterior wall finishing construction methods have been proposed, but the current trend is to use existing construction methods due to problems such as economy, weight, and durability. On the other hand, in countries such as Germany and Japan, ceramic sidings are used as exterior finishing material for buildings, which is environmentally friendly, excellent natural beauty, long life, easy maintenance and high-quality exterior materials. However, those ceramic sidings have still the problems such as manufacturing cost and weight problem because of boosting the sintering temperature up to 1,350℃ or more. Also, conventional CRC, MgO, FRP sidings which are composed of pulp, glass fiber and organic materials, have been reports of deformation due to ultraviolet rays, discoloration, corrosion and scattering, surface rupture, lifting and peeling. Therefore, in this study as an alternative to solve this problem, halosite nano kaolin produced in Sancheong in Korea and frit flux were used to satisfy the required properties as ceramic siding using low temperature sintering (below 1,000℃) and lightweight materials such as pearlite. This study aims to design the optimal formulation and process of materials and to study the characteristics of nano-coated ceramic siding material development and to present relevant basic data. The findings show that ceramic siding for nanocoated building materials is excellent as a natural ceramic siding building material. The fire resistance of natural minerals and nano particle refining technology satisfy the bending strength of 80kgf / cm2, the volume ratio of 2.0 and the absorption rate of less than 10.0%.

• Korean Journal of Metals and Materials
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• 제47권12호
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• pp.797-810
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• 2009

A study was made of the effects of a Sn addition on the microstructure and microfracture mechanism of squeeze cast AZ51-xSn magnesium alloys. Microstructural observation, in situ fracture testing, and fractographic observations were conducted on these alloys to clarify the microfracture process. The microstructural analyses indicated that $Mg_2Sn$ particles as well as $Mg_{17}Al_{12}$ particles precipitated mainly along the solidification cell boundaries; the volume fraction of these hard particles increased as the amount of added Sn increased, with increased the strength. From in situ fracture observations of the AZ51-7Sn alloy, coarse precipitates located on the cell boundaries worked as easy crack propagation sites and caused abrupt intercellular fracturing. On the other hand, the overall fracture properties of the AZ51-3Sn alloy improved because crack propagation proceeded into the Mg matrix rather than into the cell boundaries as twins developed actively, as confirmed by an R-curve analysis. These findings suggest that the addition of 3~5 wt.% Sn is effective in improving both the tensile and fracture properties on the basis of well-developed twins, the blocking of crack propagation, and crack blunting.

• Journal of Family Relations
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• 제23권3호
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• pp.131-152
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• 2018

Objectives: The purpose of this study was to compare the first echo boomer to second in the needs for family strengths and family functions, after controlling the sociodemographic characteristics. Method: For this study, a survey was conducted with 406 never-married young adults, which has 182 first echo boomers and 224 seconds echo boomers as using the same self-report questionnaire. Results: First, the two echo boomer groups exhibited similar patterns in their perception of the three family strengths, positive family values, pursuit of coexistence, and spiritual value, in that order. On the other hand, in regard to family functions, groups' perceived emotion entertainment leisure function as core functions of the family, but the second echo boomers, unlike the first echo boomers, expressed a higher need for economic functions rather than functions for children generation. Second, the analysis of this study indicated that, even in cases where first and second echo boomers had the same social-demographic characteristics, the latter in contrast with the former tended not to regard spiritual values such love for shared ethical values, compassion, and religious beliefs as a family strength, and did not require functions for children generation of the family. Conclusions: From these findings, the differences in the needs for family strengths and functions expressed by the two generations belonging to two different birth cohorts were influenced by various changes in Korean society occurring between the two generations, such as the social divergence in the functions of care and nurture, the increase in one-person and childless households, and the weakening of kinship-centered or communitarian forms of familism.

• Korean Journal of Metals and Materials
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• 제56권12호
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• pp.845-853
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• 2018

To understand the effect of microstructural factors (i.e., the size of ${\alpha}$ phase, equiaxed vs bimodal structure) on high cycle fatigue (HCF) and fatigue crack propagation (FCP) behaviors of mill-annealed Ti-6Al-4V (Ti64) alloy, three specimens of EQ (equiaxed)-8 (8 indicates the size of ${\alpha}$ grain), BM (bimodal)-8, and BM-16 were studied. The uniaxial HCF and FCP tests were conducted at an R ratio of 0.1 under sinusoidal fatigue loading. The microstructural influence (i.e., EQ vs BM) was not significant on the tensile properties of mill-annealed Ti64 alloy, and showed an increase in tensile strength and elongation with decreasing gauge thickness from 50 mm to 1.3 mm. The microstructure, on the other hand, affected the resistance to HCF substantially. It was found that the EQ structure in mill-annealed Ti64 has better resistance to HCF than the BM structure, as a result of different crack initiation mechanism. Unlike HCF behavior, the effect of microstructural features on the FCP behavior of mill-annealed Ti64 was not significant. Among the three specimens, BM-16 specimen showed the highest near-threshold ΔK value, probably because it had the greatest slip reversibility with large ${\alpha}$ grains. The effect of microstructural factors on the HCF and FCP behaviors of mill-annealed Ti64 alloy are discussed based on fractographic and micrographic observations.

• The Journal of the Korea Contents Association
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• 제21권3호
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• pp.364-374
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• 2021

In a fiercely competitive market, brands have become an important foundation for people to choose their products, and brands are also symbols of people's status and strength. Therefore, the importance of brand image design is growing. And color is an expression of emotion and can improve the communication and marketing environment of brand image as an important element of brand image. In this study, Interbrand selected Korea-China TOP 50 brand as a survey target in 2019 and downloaded brand CI from each brand's homepage to data images through Adobe Photoshop program and HSB system, and analyzed the color of the brand. There is no big difference in analyzing the color characteristics of Korean and Chinese brands, and the I.R.I color image scale analysis shows that the overall design of Korean brands is vibrant, elegant and warm to consumers. On the other hand, the overall design of the Chinese brand offers consumers a solemn, modern and sophisticated emotional adjective. Based on the results, this study can provide practical implications for companies to select colors and forms when launching their own brands and developing products.

• Journal of Korea Foundry Society
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• 제41권1호
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• pp.3-10
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• 2021

In the compound casting between the aluminum alloy and the cast iron, the iron component may be dissolved from the cast iron during the process and mixed into the aluminum melt, thereby forming various iron-containing intermetallic compounds and significantly deteriorating the tensile properties of the aluminum alloy. On the other hand, unlike Fe, which is added as an impurity, Cu is added to improve the mechanical properties of the aluminum alloy. In this study, the change in microstructure and tensile properties of aluminum alloys due to the addition of Fe and Cu was investigated. A large amount of iron-containing compounds such as coarse Al₅FeSi phases were formed when the iron content was 1% or more, and the tensile properties were significantly reduced. In the case of the aluminum alloy to which Cu was added, an Al₂Cu phase was additionally formed and the tensile strength was clearly improved.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• 제27권3호
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• pp.141-147
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• 2021

The foreign trends of noncompliance occurring frequently in food contact materials during the period of 2011-2019 was investigated by analyzing the food safety risk information DB in the National Food Safety Information Service (NFSI). A total of 2,042 cases of noncompliance of food utensils, containers, and packages were classified into 5 violation categories; administrative procedures, manufacturing and processing standards, residues and migration standards, labeling and advertising, and quality standards. This was again subcategorized according to non-compliance causative factors. The non-compliances in residues and migration standards comprised the largest proportion (76.4%) of the violative categories. The number of noncompliance information collected in 2011 was 88 cases and increased to 373 cases in 2019. A 72.8% of the non-compliance case was identified to be products of 4 countries (China 64.2%, Germany 4.0%, Japan 3.2%, and Taiwan 3.1%), those produce large quantities of containers and packaging products. During the period of 2011-2019, the number of illegal use of hazardous materials and illegal recycling of waste synthetic resins has decreased to less than one a year since 2014. On the other hand, after 2016, inconsistency of heat-resisting temperature labeling (Taiwan), non-compliance in paper container's strength standards, violation of printing standards, and the risk of consumer injury while using the products were newly reported due to the strengthening of consumer safety protection regulations. Migration of hazardous substances in synthetic polymer products such as heavy metals, melamine and formaldehyde in melamine tableware, primary aromatic amines which are colorant components in kitchenware such as ladles and spatulas, and phthalate plasticizers have been continuously reported with high frequency.

• Journal of the Korean Dietetic Association
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• 제28권2호
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• pp.114-126
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• 2022

The relationship between mortality and the Korean Healthy Eating Index ("KHEI") is well established. This study was to investigate the associations between health habits, mental health, and nutritional status and KHEI in older Koreans (aged≥65 years). A total of 4,247 subjects (1,842 men and 2,405 women) that participated in the 2016~2018 Korean National Health and Nutrition Examination Survey were included in the analysis. The lowest scoring KHEI item was milk and milk products. KHEI tertile groups were classified by total KHEI score. Tertile group percentages were related to general characteristics such as gender, residential area, educational level, income level, number of family members, and age. Logistic regression analysis adjusted for general characteristics, showed that ex-smokers (OR: male 1.53 female 2.29), smokers (OR: male 2.90), low hand grip strength (OR: male 1.42 female 1.90), poor self-rated health status (OR: female 1.83), stressful mental status (OR: female 1.51), poor health-related quality of life (OR: female 1.64), poor nutritional status (OR: male 2.88~37.20 female 1.98~16.12), and food insecurity (OR: male 6.87 female 2.03) were significantly related to a lower KHEI. This study suggests that gender-specific associations exist between mental health status and KHEI.

• Journal of the Korean Society for Heat Treatment
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• 제35권4호
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• pp.185-192
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• 2022

Variations in the microstructure and mechanical properties of API X70 steel processed by piping, electrical resistance welding (ERW), and post seam annealing (PSA) are investigated in this study. In the welding zone, some elongated pearlites are formed and grains coarsening occurs due to extra heat caused by the ERW and PSA processes. After the piping, the base metal shows continuous yielding behavior and a decrease in yield and impact strengths because mobile dislocation and back stress are introduced during the piping process. On the other hand, the ERW and PSA processes additionally decreased the impact strength of welding zone at room and low temperatures because some elongated pearlites easily act as crack initiation site and coarse ferrite grains facilitate crack propagation. As a result, the fracture surface of the welding zone specimen tested at low temperature revealed mostly cleavage fracture unlike the base metal specimen.

• The Journal of Engineering Geology
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• 제32권3호
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• pp.389-399
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• 2022

Observations on the influence of the fluid infiltration on the breakdown pressure during laboratory hydraulic fracturing tests, along with an analysis of the applicability of the breakdown pressure prediction for cylindrical samples using Quasi-static and Linear Elastic Fracture Mechanics approaches were carried out. These approaches consider fluid infiltration through the so-called radius of fluid infiltration or crack radius, a parameter that is not a material property. Two sets of tests under pressurization rate controlled and injection rate controlled tests were used to evaluate the applicability of these methods. The difficulty of the estimation of the radius of fluid infiltration was solved by back calculating this parameter from an initial set of tests, and later, the obtained relationships were used to predict breakdown pressures for a second set of tests. The results showed better predictions for the injection rate than for the pressurization rate tests, with average errors of 3.4% and 18.6%, respectively. The larger error was attributed to differences in the testing conditions for the pressurization rate tests, which had different applied vertical pressures. On the other hand, for the tests carried out under constant injection rate, the Linear Elastic Fracture Mechanics solution reported lower errors compared to the Quasi-static solution, with values of 3% and 3.8%, respectively. Moreover, a sensitivity analysis illustrated the influence of the radius of fluid penetration or crack radius and the tensile strength on the breakdown pressure, suggesting a need for a careful estimation of these values. Then, the calculation of breakdown pressure considering fluid infiltration in cylindrical samples under triaxial conditions is possible, although larger data sets are desirable to validate and derive better relations.