• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.227-234
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• 2022

In this study, the rheological properties of cement paste composites applied with carbon-based nano-materials were experimental analyzed. Flow table and rheological properties, compressive strength were measured in the cement paste using graphene oxide asqueous solution and carbon nanotube aqueous solution. When carbon nano-materials was mixed in an aqueous solution, flow decreased and plastic viscosity and shear stress were increased. In particular, graphene oxide rapidly increased the plastic viscosity and shear stress. In the case of carbon nanotube aqueous solution, when less than 0.2 % was mixed, the increase rate was low compared to graphene oxide. This is because the specific surface area of graphene, which is in the form of a plate, is large. The compressive strength showed a small amount in strength increase when graphene mix, and CNT had a strength about 112 % of OPC. Carbon-based nanomaterials, is considered that CNT are suitable more to be used construction materials. However, extra studies on the surfactant to be used for mixing proportion and dispersion will be needed.

• Journal of Korean Home Economics Education Association
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• v.32 no.4
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• pp.67-79
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• 2020

The purpose of the study were to analyze the patterns of adolescent suicide attempts, and to explore the effects of personal psychology (subjective depression, subjective stress), health status (BMI, subjective health perception), and subjective academic performance on the types of youth suicide attempts. For this research, data of 'The 15th Korea Youth Risk Behavior Survey' were analyzed employing a hierarchical logistic regression analysis. The findings are as follows. First, out of 1,731 youth suicide attempts 156 (9%) were impulsive and 1,575 (91%) were planned. Girls(67.3%) attempted suicide more than boys (32.5%), and middle school students (62%) attempted suicide more than high school students (38%). Second, the variables that significantly affect suicide attempt types were subjective depression, subjective stress, and subjective health perception, after controlling for gender, grade level, school type, and SES. The rate of planned suicide attempts was higher among those who experienced depression than among those who did not. In the case of subjective stress, adolescents who felt stressed were likely to commit planned suicide attempts. Those who attempted impulsive suicide showed 1.32 times higher subjective health perception scores than those who attempted planned suicide, indicating adolescents who perceived they were not healthy were more likely to attempt planned suicide. BMI and subjective academic performance did not have a significant effect on the types of youth suicide attempts. These findings suggested the necessity of systematic intervention in Home Economics classes or extra-curricular programs, to prevent potential youth suicide attempts.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.378-385
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• 2021

The purpose of this study is to analyze the effects of a comparative process so that students majoring in urban planning and design can develop the ability to present non-physical alternatives along with the ability to present alternatives to a physical environment to solve urban problems. A total of 30 students majoring in urban planning and urban design were analyzed for their satisfaction with their majors, intention to find a job related to their majors, and academic achievement. This was done after conducting a comparative course of living-lab projects utilizing idle space in a region in connection with a major education course for about a year. For the analysis, the four-group design used by Solomon was used to find the differences between students who participated in the class and those who did not. The analysis showed that the students who participated in the comparative course of the living-lab project were highly satisfied with their major and their intention to find a job related to their major. The results of this study suggest that the process of cultivating the ability to work with local residents and merchants to present physical and non-physical alternatives to solve local problems by utilizing the means of living lab projects has a positive effect on the students' attachment to their majors and their self-esteem.

• Advances in nano research
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• v.13 no.6
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• pp.575-585
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• 2022

Due to its biofilm formation and colonization of the osteocyte-lacuno canalicular network (OLCN), Staphylococcus aureus (S.aureus) implant-associated bone infection (SIABI) is difficult to cure thoroughly, and may occur recurrently subsequently after a long period dormant. It is essential to explore an alternative therapeutic strategy that can eradicate the pathogens in the infected foci. To address this, the polymethylmethacrylate (PMMA) bone cement and Fe3O4 nanoparticles compound cylinder were developed as implants based on their size and mechanical properties for the alternative magnetic field (AMF) induced thermal ablation, The PMMA mixed with optimized 2% Fe₃O₄ nanoparticles showed an excellent antibacterial efficacy in vitro. It was evaluated by the CFU, CT scan and histopathological staining on a rabbit 1-stage transtibial screw model. The results showed that on week 7, the CFU of infected soft tissue and implants, and the white blood cells (WBCs) of the PMMA+2% Fe₃O₄+AMF group decreased significantly from their controls (p<0.05). PMMA+2% Fe₃O₄+AMF group did not observe bone resorption, periosteal reaction, and infectious reactive bone formation by CT images. Further histopathological H&E and Gram Staining confirmed there was no obvious inflammatory cell infiltration, neither pathogens residue nor noticeably burn damage around the infected screw channel in the PMMA+2% Fe₃O₄+AMF group. Further investigation of nanoparticle distributions in bone marrow medullary and vital organs of heart, liver, spleen, lung, and kidney. There were no significantly extra Fe₃O₄ nanoparticles were observed in the medullary cavity and all vital organs either. In the current study, PMMA+2% Fe₃O₄+AMF shows promising therapeutic potential for SIABI by providing excellent mechanical support, and promising efficacy of eradicating the residual pathogenic bacteria in bone infected lesions.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.2
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• pp.197-205
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• 2022

This study was conducted to investigate the fluoride release of fluoride-containing restorative materials in fluoride recharging according to the concentration of fluoride toothpaste used in Korea. Samples of glass ionomer cement, resin-modified glass ionomer cement, alkasite restorative material, and composite resin were prepared and fluoride release was measured on days 1, 3, 7, 14, 21, 28. Thereafter, fluoride-free, 500 ppm, and 1450 ppm fluoride toothpaste was applied to each restorative materials, and the fluoride release was measured on days 1, 3, 7. Glass ionomer cement showed the highest cumulative fluoride release until the 7th day of measurement, and from the 14th day onwards, the resin-modified glass ionomer cement showed the highest cumulative fluoride release, but there was no significant difference. When restorative material groups were recharged with 500 ppm of fluoride toothpaste, the fluoride release was significantly higher only for the alkasite restorative material compared to the fluoride-free toothpaste group (p < 0.017). When restorative material groups were recharged with 1450 ppm of fluoride toothpaste, the fluoride release was significantly higher in all restorative groups compared to the fluoride-free toothpaste group (p < 0.017).

• The Korea Journal of Herbology
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• v.36 no.6
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• pp.27-37
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• 2021

Objectives : In the current study, we performed the 13-week repeated oral dose toxicity test and a 4-week recovery test of standardized Cornus officinalis Sieb. et Zucc. and Psoralea corylifolia L. 30 % ethanol extract (SCP) in Sprague-Dawley (SD) rats owing to aims for verifying no observed adverse effect level (NOAEL). Methods : The animal study was performed according to OECD guidelines for the testing of chemicals section 4 health effects test No.408 repeated dose 90-day oral toxicity study in rodents (03 October 2008). In the repeated dose toxicity study, SCP was orally administered to female and male rats at dose levels of 1,000, 2,000, and 4,000 mg/kg/day for 13-week. The control group and high dose (4,000 mg/kg/day) group were then monitored for 4 extra weeks to determine recovery time after the study period. 1) Results : Compared with the control group, there were no treatment-related adverse effects in clinical signs, body weight, hematology, serum biochemistry (Aspartate aminotransferase, Alanine aminotransferase, Alkaline phosphatase, 𝛾-Glutamyl transpeptidase, Blood urea nitrogen, Creatinine, Glucose, Total cholesterol, Total protein, Creatine phosphokinase, Albumin, Total bilirubin, Triglyceride, Inorganic phosphorus, Albumin/Globulin ratio, Calcium ion, Sodium ion, Potassium ion, Chloride ion), necropsy findings and organ weight (Ovary, Adrenal gland, Pituitary, Thymus, Prostate, Testis, Epididymis, Spleen, Kidney, Heart, Lung, Brain, Liver) at any dose tested. Conclusions : Taken together, these results suggest that the NOAEL of SCP in both genders was considered as over 4,000 mg/kg. Results from this study provide scientific evidence for the safety of SCP.

• Korean Journal of Construction Engineering and Management
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• v.23 no.6
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• pp.89-100
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• 2022

The development of the Construction Production Rates System for appropriate construction cost calculation has recently come to the fore as a means of invigorating OSC based PC structure which currently needs institutional frameworks. PC structure based construction expenses consist of the factory-built assembly, transportation and on-site installation. Recently, in the field of transportation and site installation, research on product structure development is being conducted, such as presenting the standard product calculation system reflecting the results of field survey for each subsidiary materials (Lee et al., 2021). On the other hand, there is no ongoing research on estimating construction expenses of Factory-built assembly. This study suggests Construction Production Rates System which can be used for PC subsidiary materials based Factory-built assembly cost estimations. For the research, work types for the construction procedures have been categorized, and the standard input manpower suitable for the corresponding work characteristics has been derived from analyzing the associated Construction Standard Production Rates for each work type. Also, as the research referred PC subsidiary materials (such as columns, beams, walls, and slab, as well as on-site installation) and the standard number of workforce based on work types, one can calculate direct labor cost, using what the research shows. In addition, it suggests that the size of individual subsidiary materials be the extra cost factor, by using the characteristics that productivity changes depending on the size(m³) of subsidiary materials. It is expected that the research can contribute to objectively verifying factory-built assembly cost through of PC structure, which currently relies on estimates.

• Journal of Nutrition and Health
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• v.55 no.4
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• pp.419-429
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• 2022

Water accounts for the largest proportion of body weight and is an essential element for the physiological functioning of the human body. According to 2013-2017 Korea National Health and Nutrition Examination Survey (KNHANES) data, the average water intake of Koreans was 2,167.3 mL/day and 62% of them did not meet the Dietary Reference Intakes for Koreans (KDRIs) for water. However, the consumption of beverages is continuously increasing. KDRIs sets the adequate intake (AI) for water, but tolerable upper intake level (UL) and chronic disease risk reduction intake (CDRR) are not provided. Compared to 2015, the AI of total water from both food and fluids in the 2020 KDRIs slightly increased or decreased according to age. The AI for children 1-2 years old, boys 6-8 years and 9-11 years old, and girls 6-8 years old decreased by 100 mL/day, while that of boys 12-14 years old increased by 100 mL/day. The AI of total water was the sum of the water intake from food and fluids reported by the KNHANES, with an extra milk intake of 200 mL/day. Therefore, it is not appropriate to use the AI of total water intakes for the reference of beverage intakes. It is preferable to consume water or milk rather than beverages containing sugar and others including caffeine, sodium, etc. when drinking fluid water. We suggest the following improvements in the future KDRIs for water: improving the adequacy of the water content ratio of Korean conventional foods, supplementing the fluid water intake survey, reflecting the current water intake status by life cycle, setting KDRIs for water for the elderly considering the physiological changes, health status and dietary habits, and promotion of research on the relationship between water intake and health for Koreans.

• Korean Journal of Poultry Science
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• v.50 no.1
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• pp.23-30
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• 2023

This study was conducted to analyze the correlation between egg breakage rate and cumulative external forces on eggs during the egg transfer system in 12 commercial layers farms. The commercially available electronic egg device was used to detect the external forces on eggs during egg collection systems. In addition, egg breakage rate per farm was collected. It was found that the external force on eggs were greater in the order of washer and dryer connection part, conveyor connection part, transfer, sorter, collecting elevator, packer, egg transfer connection part, and egg tray. A positive relationship between the external forces on eggs during egg transit system and the incidence of cracked eggs per farm was noted. The external forces on eggs varied from 5G to 38G depending on the location and the egg breakage rate ranged from 3.2 to 14.5% per farm. Although efforts to produce eggs with high eggshell quality are considered important, extra care should be made to lower the external forces on eggs during the egg transfer system from laying house to egg packing center.

• Journal of Animal Science and Technology
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• v.64 no.3
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• pp.574-587
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• 2022

This study was performed to development the alternative farrowing pen (AFP) and to investigate performance and behavior of lactating sows and their litter. A total of 64 multiparous sows were randomly divided into two groups and were allocated to farrowing crates (FCs) and AFPs. The AFPs contained a crate and support bars that could be folded to provide the sows with extra space on day 5 postpartum. Behavior was recorded by charge-coupled device cameras and digital video recorders, and the data were scanned every 2 min to obtain an instantaneous behavioral sample. Farrowing systems did not affect feed intake, back-fat thickness, litter size and piglet weight at birth and weaning (p > 0.05). In addition, there were no differences in the number of crushed piglets between the two farrowing systems (p > 0.05). However, the weaning-to-estrus interval was shorter in the sows of the AFPs than in thous of the FCs (p < 0.05). The sows spent most of their time lying down during the lactating period, at about 80% lateral recumbency and 10%-15% ventral recumbency. The only significant differences were in the feeding and drinking behavior between sows in the two farrowing systems (p < 0.05). The FC sows displayed more feeding and drinking behavior than the AFP sows, especially in the late lactating period (p < 0.05). Piglets in the FCs tended to spend more time walking than piglets in the AFPs (p < 0.05), whereas there were no differences in suckling and lying behavior between piglets in the two farrowing systems (p > 0.05). It is concluded that the AFPs with temporary crating until day 4 postpartum did not negatively affect performance and crushed piglet compared with the FCs. It also may improve animal welfare by allowing sows to move and turn around during the lactating period. Further research is needed to find suitable housing designs to enhance productivity and animal welfare.