• Korean Chemical Engineering Research
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• v.53 no.6
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• pp.792-797
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• 2015

Graphene has a wide spectrum on its application field due to various and excellent physical properties. However, it is very difficult to apply that graphene exists as lump or fold condition in general organic solvents. Besides, graphene was difficult to maintain as uniform condition due to chemical inert and distributions with various size and shapes. Therefore, this study was focused to study dispersion and modifying methods of aggregated graphene. The dispersion methods contain as follow: i) physical milling using glass bead, ii) co-treatment of glass bead and ultrasonic waves, iii) dispersion in organic solvents, iv) modifying with dry-ice. Milling using glass bead with size 2.5 mm was effective to be size decrease of 36.4% in comparison with control group. Mixed treatment of glass bead (size 2.5 mm) and ultrasonic waves (225W, 10 min) showed relative size decrease of 76%, suggesting that the size decrease depends on the size of glass bead, intensity of ultrasonic waves and treatment time. Solvents of Ethyl acetate (EA) and Isoprophyl alcohol (IPA) were used in order to improve dispersion by modifying surface of graphene. IPA of them showed a favorable dispersion with more -CO functional groups in the FT-IR analysis. On the other hand, the oxygen content of graphene surface modified by dry-ice was highly increased from 0.8 to 4.9%. From the results, it was decided that the favorable dispersion state for a long time was obtained under the condition of -CO functional group increase in IPA solvent.

• Child Health Nursing Research
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• v.6 no.2
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• pp.158-166
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• 2000

The purpose of this study was to confirm the efficient umbilical cord care of healthy newborns in nursery. In order to determine the efficient care, the time of umbilical cord separation and the skin condition of periumbilical area were evaluated. The data were collected in sample of 529 normal, healthy newborns of C hospital in Seoul, from September 1st, 1999 to January 16th, 2000. The babies were randomly selected and allocated into four groups-alcohol swab/tub bath, alcohol swab/partial bath, natural dry/tub bath, natural dry/partial bath- by the methods of care. The mothers of babies were also surveyed by questionnaire about general characteristics. The data were analyzed by SAS program. The results of this study were as follows : 1. The average gestation period of newborns was 39+3 weeks. The average birth weight was 3.27Kg. In gender of babies, boys were 51.7% and girls were 48.3%. The 65% of newborns were born normal vaginal delivery, 35% were C-section. The feeding methods were 55.3% of the babies fed by mixed type, 22.9% by breast, and 21.8% by bottle. There was no significance among four groups by general characteristics. 2. The average time of umbilical cord separation was 8.27 days(SD=2.3). The time was no difference significantly among four groups(F=1.68, P=0.17). 3. The prevalence of the umbilical care complication did not show differences among four groups( 2=3.93, P=0.27). In conclusion, Nurses have preferred the traditional alcohol swab/partial bath method in care of newborns. But there was no difference among the ways to take care of umbilicus according to this study. The way to naturally is more efficient due to reduce the time and expense in umbilical care for normal babies of nursery. This also matched the change in approach to healthy population from intervention to nonintervention way. This could be suggested in education for normal and healthy babies care at home and nursery as a useful way. Endly, the further study about bacterial colony nda infection rate at umbilicus by ways of care is needed.

• Journal of the Korean Geosynthetics Society
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• v.19 no.2
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• pp.13-21
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• 2020

In Korea, small reservoirs have been constructed for the supply of agricultural water, but most of them have been over 50 years from the year of construction. Aging agricultural reservoirs are being investigated for serious defects such as leaks and movements in slope, which are very vulnerable to safety. Accordingly, grouting methods are used to reinforce aging agricultural reservoirs in Korea. However, cement used as a grouting injection material consumes natural resources and generates a large amount of greenhouse gases during production. In addition, there is a problem that sufficient reinforcement is not made due to various factors such as the injection amount, the compounding ratio, the injection pressure, and etc. Therefore, due to these problems, the development of new materials and methods that can replace the grouting method and cement is required. In order to solve these problems, this study conducted an laboratory test on the surface stabilizer used to secure the stability of road and rail slopes. In addition, the program was analyzed and the reinforcing effect was examined when the surface stabilizer was used as reinforcement material for aging agricultural reservoir. As a result of the laboratory test, when the surface stabilizer is mixed, the increase of cohesion is possible up to 9% and there is no change in the friction angle. The results of the program analysis showed that the 1.0m reinforcement of slopes increased the factor of safety by 1.4 times, making it possible to reinforce the aging agricultural reservoir using surface stabilizers. And as a reinforcement method, it was analyzed that it is most appropriate to reinforce the slope and the bottom of slope simultaneously.

• Fisheries and Aquatic Sciences
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• v.24 no.1
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• pp.19-31
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• 2021

Seaweeds are a potential source of minerals, essential amino acids, fatty acids, proteins, and various bioactive compounds such as antioxidants. The higher water content of seaweeds reduces the shelf life and this requires the appropriate drying method. The drying conditions play a major role in the conservation of nutrient composition in dried seaweeds. In recent years, the seaweed industry has used many different drying methods with advantages and limitations. Hybrid hot-water Goodle dryer (HHGD) which is a special dryer mixed with hot-water and a Korean traditional heating system (Goodlejang) might be a solution to avoid these limitations. The present study evaluated the effect of drying conditions in HHGD on nutrient composition and bioactivities of brown seaweeds. Moreover, freeze-dryer (FD) and HHGD were employed in this study to compare the dried outputs obtained from four brown seaweed species. The present study aims to evaluate the effect of the hybrid hot-water Goodle drying method (HHGDM) on the nutritional composition and antioxidant activity of dried seaweeds. AOAC standard methods were used to analyze the proximate composition of dried samples and their 70% ethanol extract. The intracellular and extracellular antioxidant activities were evaluated using Vero cells and electron spin resonance (ESR) spectrometer respectively. High performance liquid chromatography, apoptotic body formation, and in-vivo experiments were used for further confirmation of the quality of dried output. The proximate composition results obtained from drying in HHGD and FD did not exhibit any significant difference. Moreover, the seaweed extracts from the dried seaweeds by HHGD and FD dryings were also not different and both significantly down-regulated in-vivo and in-vitro oxidative stress. Furthermore, the high performance liquid chromatography results revealed that the two dryers did not make the major peaks different in the chromatograms. Freeze-drying method (FDM) provides elevated quality for dried output, but there are limitations such as high cost and low capacity. The results from a novel HHGD did not provide any significant difference with the results in FD and expressed a potential to avoid the limitations in FD. Overall, these findings solidified the applicability of HHGD over FD.

• Safety and Health at Work
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• v.13 no.2
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• pp.163-169
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• 2022

Background: It is estimated that about 13 million artisanal and small-scale miners carry out their activities under harsh, precarious, unfriendly, and risky conditions. Yet, our understanding of the extent to which these workers use personal protective equipment (PPE) and navigate through the various risks and hazards they face is still limited. This article has two main objectives. First, it explores the extent of usage of PPE among artisanal and small-scale miners for the prevention of hazards and risks. Second, it examines the coping strategies used by these miners as a response to experiences of occupational injuries and risks Methods: A cross-sectional survey of small-scale miners was conducted in six communities across three districts in Ghana, West Africa. The mixed methods approach was adopted. A total of 148 small-scale miners participated in the study. Six focus group discussions (FGDs) were held across the six communities. The data were analysed using descriptive statistics. Chi-square tests were used to analyse the relationship between some socio-demographic characteristics (sex, age, and educational background) and the usage of PPE. Open-ended questions and responses from FGDs were analysed based on the content and verbatim quotations from miners. Results: Findings suggest that 78% of the miners interviewed do not use the appropriate PPE citing reasons such as cost, and their personal discomfort associated with use of PPE. There was no significant relationship between socio-demographic characteristics (i.e., sex, age, education and major mining activity) and the usage of PPE. The study further revealed four main coping strategies used by miners to handle the risks. These are rest, taking unprescribed medication and hard drugs, registration with health insurance scheme and savings and investments. Conclusion: This study shows that very few artisanal miners use PPE despite the significant hazards and risks to which they are exposed. The study recommends to the government to put in place measures to ensure that miners adhere to health and safety regulations before undertaking mining activities. This means that health and safety plans and use of PPE should be linked to the license acquisition process for miners.

• Journal of Urban Science
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• v.11 no.1
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• pp.49-57
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• 2022

Semi-industrial zone is the area where manufacturing, residential, commercial zones are mixed. Despite of their potentials in that proximity to city and convenient transportation infrastructure, a lot of semi-industrial zones in Korea have converted to other uses due to many issues such as change of industry, increasing land price, real estate speculations. Recently, local government is trying to solve their existing issues and develop them through a restoration of publicness. Now publicness is thought of as a key factor of regeneration in semi-industrial areas. In this regard, this study aims to examine the way of restoring publicness revealed in Brooklyn Navy Yard mainly focus on their urban contexts and architectural ways. Brooklyn Navy Yard, an exemplary case, is an industrial complex that has grown economically, socially and culturally through emphasizing publicness and it is evaluated as an advanced example of public industrial complex. Through the analysis of Navy Yard, this study was trying to emphasize the importance of publicness in the regeneration of semi-industrial areas and to provide implications for the Seoul Government's solutions, which are still in the conceptual stage. To analyze the publicness of the study subjects, framework and elements were derived by examining related theories and prior researches. Depending on this frame, the results of the publicness of the Navy Yard were as follows. First of all, the 'Publicness as an officiality' was identified at the characteristic of the site and Navy Yard development corporation. Second, the 'Publicness as a public interest' of the Navy Yard Development Corporation was identified in various ways of its operation methods. Finally, the 'Publicness as an accessibility' was identified in the opening of urban and architectural spaces in Navy Yard. These publicness were analyzed with seven Navy Yard's success factors. Thus, it can be interpreted that the publicness of the semi-industrial areas can contribute significantly to their success. The publicness restoring methods of Navy Yard could be used as a basic data in semi-industrial areas in the future in Korea. However they are limited to be applied directly, so extensive and in-depth research in terms of their applicability should be conducted.

• IMMUNE NETWORK
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• v.8 no.1
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• pp.21-28
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• 2008

Background: A co-inhibitory molecule, B7-H4, is believed to negatively regulate T cell immunity by suppressing T cell proliferation and inhibiting cytokine production. However, the mechanism behind B7-H4-mediated tolerance remains unclear. Methods: Balb/c $(H-2^d)$ mice were fed with dendritic cell line, DC2.4 $(H-2^d)$ every day for 10 days. Meantime, mice were hydrodynamically injected with recombinant plasmid expressing B7-H4 fusion protein (B7-H4.hFc) or hFc via tail vein. One day after last feeding, mice were immunized with allogeneic B6 spleen cells. 14 days following immunization, mice were challenged with B6 spleen cells to ear back and the ear swelling was determined the next day. Subsequently, a mixed lymphocyte reaction (MLR) was also performed and cytokines profiles from the reaction were examined by sandwich ELISA. Frequency of immunosuppressive cell population was assayed with flow cytometry and mRNA for FoxP3 was determined by RT-PCR. Results: Tolerant mice given plasmid expressing B7-H4.hFc showed a significant reduction in ear swelling compared to control mice. In addition, T cells from mice given B7-H4.hFc plasmid revealed a significant hyporesponsiveness of T cells against allogeneic spleen cells and showed a significant decrease in Th1 and Th2 cytokines such as IFN-${\gamma}$, IL-5, and TNF-${\alpha}$. Interestingly, flow cytometric analysis showed that the frequency of CD4+CD25+FoxP3+ Tregs in spleen was increased in tolerant mice given recombinant B7-H4.hFc plasmid compared to control group. Conclusion: Our results demonstrate that B7-H4 synergistically potentiates oral tolerance induced by allogeneic cells by increasing the frequency of FoxP3+ CD4+CD25+ Treg and reducing Th1 and Th2 cytokine production.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.45-53
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• 2000

Enamel microabrasion is a means by which superficial enamel discoloration is removed using hydrochloric acid and fine pumice. As enamel microabrasion alone may not be sufficient in cases of deeper discoloration, composite resin restoration is recommended in areas where there is remaining discoloration. The purpose of this study was to investigate the effects of different methods and number of applications of enamel microabrasion on the shear bond strength of composite resin to enamel. Untreated control was designated as group 1. 5-second applications of a mixture of 18% HCl and fine pumice were performed 5 and 10 times on groups 2 and 3, respectively. A commercially available mixture of 10% HCl and abrasives(PREMA) was applied using a 10 : 1 gear reduction handpiece 5 and 10 times on groups 4 and 5, respectively, with each application lasting 20 seconds. After etching with 37% phosphoric acid, composite resin was bonded. Thermocycling was performed and shear bond strength was measured. The following results were obtained : 1. Group 2 showed the highest bond strength$(24.36{\pm}3.34)$, while group 3 showed the lowest$(19.35{\pm}3.43)$, Shear bond strength decreased in the following order: 2>4>5>1>3. 2. Group 2 showed bond strength significantly higher compared to groups 1 and 3(p<0.05). 3. There were no significant differences between groups 2 and 3, which had been microabraded using HCl and pumice, and groups 4 and 5, to which PREMA had been applied, when bond strengths were compared(p>0.05). 4. When modes of fracture were examined, adhesive failure was observed in groups 3 and 4, while cohesive failure was observed in groups 1, 2, 3 and 4. Only mixed failures were found group 5. 5. When viewed using a SEM, groups 2 and 3, which had been microabraded using HCl and pumice, showed surface appearances similar to that of enamel etched with phosphoric acid. Groups 4 and 5, treated with PREMA, exhibited a smooth surface similar to that of group 1. All oops showed similar, typical surface characteristics following phosphoric acid etching.

• Journal of Christian Education in Korea
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• v.77
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• pp.47-62
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• 2024

Purpose of the study : The purpose of this study was to analyze research on Christian infant parents in terms of research period, research content, and research method, and seek directions for research projects related to Christian infant parents. Research content and methods : For this study, domestic master's and doctoral dissertation published from 1995 to 2023 by the national assembly library and the research information sharing service (RISS) were collected under the categories 'Christianity', 'infant', 'infancy', and 'parent'. A total of 40 studies were extracted by searching with these keywords and excluding redundant studies. In addition, the frequency and percentage were calculated by classifying and analyzing the results into three criteria: research period, research content, and research method. Conclusions and Recommendations : Research on Christian infant parents increased significantly between 2016 and 2020, with 10 studies (25%) conducted during this period, indicating a more active engagement in this area compared to other times. Master's theses accounted for 39 studies (97.5%), while doctoral dissertation comprised 1 study (2.5%), suggesting a predominance of research at the master's level. Regarding the content of the research on Christian infant parents, practice studies accounted for 34 studies (85%), while basic research accounted for 6 studies (15%). Field-related studies such as the development of parental education programs and materials for infants continued to be carried out steadily, but there was a lack of theoretical, philosophical, perceptual, and factual investigation research on Christian infant parents. Methodologically, literature reviews were prevalent, with 27 studies (67.5%), followed by quantitative studies with 10 studies (25%), and qualitative studies with 3 studies (7.5%). Various types of research, including quantitative, qualitative, and literature reviews, were conducted between 2016 and 2020. Based on the research findings, in-depth qualitative studies conducted through observation and interviews, as well as mixed-method studies complementing single studies, should be conducted for a long-term perspective on research involving Christian infant and child parents.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.3
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• pp.231-238
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• 2022

Purpose. This study aimed to investigate the effect of different veneering methods on the tensile bond strength between polyetherketoneketone (PEKK) and denture base resins. Materials and methods. A total of 80 PEKK T-shaped specimens were fabricated and the primer (Visio.link) was applied after airborne-particle abrasion with 110 ㎛ alumina oxide powder. According to the veneering method, the specimens were divided into four groups (n = 20) to be veneered with the gingival colored packable photopolymerized composite resin (SR Adoro); flowable photopolymerized composite resin, (Crea.lign); heat-polymerized resin (Vertex); and self-polymerized resin (ProBase Cold). Each group was divided into two subgroups (n = 10) according to the artificial thermal aging. After the tensile bond strength measurement via universal testing machine, the fracture sections of all specimens were observed. Two-way ANOVA and Tukey's HSD post hoc test were used for the statistical analysis (α = .05). Results. The results of the two-way ANOVA showed statistically significant differences in the tensile bond strength according to the veneering method and artificial thermal aging of denture base resins (P<.001). The highest tensile bond strength showed in the packable photopolymerized resin group before and after the artificial thermal aging. The lowest tensile bond strength showed in the heat-polymerized resin group. The mixed and adhesive fracture showed in all groups. Conclusion. The veneering method and artificial thermal aging can influence in the tensile bond strength between the resin and PEKK. The artificial thermal aging can reduce the tensile bond strength.