• 한국생산제조학회지
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• 제9권6호
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• pp.49-56
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• 2000

Due to the rapid increase of long-distance transportation, particular attentions have been paid to truck tires, especially to their dynamic characteristics. In this research, experimental modal analysis on two kinds of light-duty truck tires, i.e., radial tire and bias tire, are performed by using GRFP(global rational fraction polynomial) method to investigate differences of the dynamic behavior of the two tires. The test results have shown that the modal frequencies of bias tire are much higher than the corresponding values of radial tire with a similar mode shape, which is in accordance with the fact that the radial rigidity of bias tire is higher than that of radial tire. And most of the modal decay rates of bias tire are larger than those of radial tire within the scope of this experiment. In the frequency domain range of test, the bias tire has extra modes, which do not occur in the radial tire. This difference is based on the fact that the circumferential rigidity of the bias tire is quire low whereas that of radial tire is so high that the frequencies of the corresponding modes are out of the frequency range of test.

• 한국재료학회지
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• 제16권12호
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• pp.743-746
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• 2006

ZTA tubes were prepared by centrifugal casting and sintered at $1600^{\circ}C$ for 2 hrs. The ZTA tubes were machined into specimens of $3{\times}4{\times}40$ mm. Molten Soda lime glass (SLG) was penetrated into the surface of ZTA at an optimized condition of $1500^{\circ}C$ for the holding time of 5 h and furnace cooled. The extra glass on the surface was removed using a resin bonded diamond wheel. The glass penetrated samples were tested for their flexural strength using four point bend test. Vickers Indentation cracks were made on the glass penetrated surface at different loads of 9.8 N, 49 N, 98 N and 196 N. The residual compression on the surface enhanced the flexural strength and crack arrest behaviour remarkably. This was attributed to the thermoelastic mismatch between the glass and ZTA matrix during cooling.

• Geomechanics and Engineering
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• 제21권4호
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• pp.337-348
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• 2020

Tropical organic soils having more than 65% of organic matters are named "peat". This soil type is extremely soft, unconsolidated, and possesses low shear strength and stiffness. Different conventional and industrial binders (e.g., lime or Portland cement) are used widely for stabilisation of organic soils. However, due to many factors affecting the behaviour of these soils (e.g., high moisture content, fewer mineral particles, and acidic media), the efficiency of the conventional binders is low and/or cost-intensive. This research investigates the impact of different constituents of cement-sodium silicate grout system on the compressibility behaviour of organic soil, including settlement and void ratio. A microstructure analysis is also carried out on treated organic soil using Scanning Electron Micrographs (SEM), Energy Dispersive X-ray spectrometer (EDX), and X-ray Diffraction (XRD). The results indicate that the settlement and void ratio of treated organic soils decrease gradually with the increase of cement and kaolinite contents, as well as sodium silicate until an optimum value of 2.5% of the wet soil weight. The microstructure analysis also demonstrates that with the increase of cement, kaolinite and sodium silicate, the void ratio and porosity of treated soil particles decrease, leading to an increase in the soil density by the hydration, pozzolanic, and polymerisation processes. This research contributes an extra useful knowledge to the stabilisation of organic soils and upgrading such problematic soils closer to the non-problematic soils for geotechnical applications such as deep mixing.

• Structural Engineering and Mechanics
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• 제46권4호
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• pp.487-504
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• 2013

In the present work a new friction device, with a set of single or double rotational friction flanges and a link element, is described and tested. The mechanism may be applied for the strengthening of existing r/c or steel buildings as well as in new constructed buildings. The device has selectable variable behavior in different levels of displacement and an interlock mechanism that is provided by the link element. The link element may be designed to lock at preselected level of displacement, offering in this way an extra safety reserve against strong earthquakes. A summary of the existing literature about other similar mechanisms is initially presented in this paper. The proposed mechanism is presented and described in details. Laboratory experiments are presented in detail and the resulted response that proves the efficiency of the mechanism at selectable levels of strength capacity is discussed. Drawings of the mechanism attached to a r/c frame with connection details are also included. Finally a dynamic analysis of two r/c frames, with and without the proposed mechanism attached, is performed and the resulted response is given. The main conclusion is that the proposed mechanism is a cheap and efficient devise for the improvement of the performance of new or existing framed buildings to seismic loads.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.1004-1012
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• 2021

High density polyethylene (HDPE) pipe has many advantages over metallic pipe, and has been used in non-safety related application for years in some nuclear power plants (NPPs). Recently, HDPE pipe was introduced into safety related applications. The main difference between safety-related and non-safety-related pipes in NPPs is the design method of extra loadings such as gravity, temperature, and earthquake. In this paper, the mechanical behavior of HDPE pipe under various loads in pipe gallery was studied by finite element analysis (FEA). Stress concentrations were found at the fusion regions on inner surface of mitered elbows of HDPE pipe system. The effects of various factors were analyzed, and the influence of various loads on the damage of HDPE pipe system were evaluated. The results of this paper provide a reference for the design of nuclear safety-related Class 3 HDPE pipe. In addition, as the HDPE pipes analyzed in this paper were suspended in pipe gallery, it can also serve as a supplementary reference for current ASME standard on Class 3 HDPE pipe, which only covers the application for buried pipe application.

• 한국보육지원학회지
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• 제16권6호
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• pp.19-34
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• 2020

Objective: This study investigated the effects of the firstborn's gender and temperament on the fertility intention and follow-up childbirth of parents. Methods: A total 120 firstborns and their mothers were selected from the sample of the Panel Study on Korean Children. Child temperament traits were measured by Early Childhood Behavior Questionnaire(ECBQ) and mothers stated their fertility intention in 2009 when their first child was under 2 years old. Follow-up childbirth of mothers was assessed from the data of PSKC in 2016. Results: The results indicated that there was a significant difference by gender in follow-up birth. Among aspects of temperament, fertility intention was affected by the firstborn's inhibitory control and follow-up birth was affected by the firstborn's gender and discomfort. For mothers with a boy, the firstborn's soothability affected mothers' follow-up childbirth. Conclusion/Implications: These results imply that gender and temperament of the first child are connected to mothers' fertility intention and follow-up childbirth. Extra studies are required to clarify how those factors affect mothers' parenting or psychological status. Meanwhile, the firstborn's gender and temperament should be considered when developing support programs for families with one child in order to increase follow-up birth rate.

• Steel and Composite Structures
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• 제42권2호
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• pp.161-172
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• 2022

In this paper, four specimens of CFST column joints with endplates and long bolts are tested in the scenario of progressive collapse. Flush endplate and extended endplate are both adopted in this study. The experimental results show that increasing the thickness of the endplate could improve the behavior of the joint, but delay the mobilization of catenary action. The thickness of the endplate should not be relatively thick in comparison to the diameter of the bolts, otherwise catenary action would not be mobilized or work effectively. Effective bending deformation of the endplate could help the formation and development of catenary action in the joints. The performance of flexural action in the joint would affect the formation of catenary action in the joint. Extra middle-row bolts set at the endplates and structural components set below the bottom beam flange should be used to enhance the robustness of joints. A special weld access hole between beam and endplate should be adopted to mitigate the chain damage potential of welds. It is suggested that the structural components of joints should be independent of each other to enhance the robustness of joints. Based on the component method, a formula calculating the stiffness coefficient of preloaded long bolts was proposed whose results matched well with the experimental results.

• Nuclear Engineering and Technology
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• 제54권11호
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• pp.4062-4071
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• 2022

Long-term aluminum (Al) corrosion tests were designed to investigate the condition that would generate severe Al corrosion and precipitation. Buffer agents of sodium tetraborate (NaTB), trisodium phosphate (TSP) and sodium hydroxide (NaOH) were adopted. The insulation materials, fiberglass and calcium silicate (Ca-sil), were examined to explore their effects on Al corrosion. The results show that significant precipitates were formed in both NaTB/TSP-buffered solutions at high pH. The precipitates formed in NaTB solution raise more concerns on chemical effects in GSI-191. A passivation layer formed on the surfaces of coupon in solution with the presence of insulations could effectively mitigate Al corrosion. The Fe-enriched intermetallic particles (IPs) embedded in coupon appeared to serve as seeds to readily induce precipitation via providing extra area for heterogeneous Al hydroxide precipitation. X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analyses indicate that the precipitates are mainly boehmite (γ-AlOOH) and no direct evidence confirms the presence of sodium aluminum silicate or calcium phosphate.

• IMMUNE NETWORK
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• 제21권3호
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• pp.20.1-20.18
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• 2021

The gut is an important organ with digestive and immune regulatory function which consistently harbors microbiome ecosystem. The gut microbiome cooperates with the host to regulate the development and function of the immune, metabolic, and nervous systems. It can influence disease processes in the gut as well as extra-intestinal organs, including the brain. The gut closely connects with the central nervous system through dynamic bidirectional communication along the gut-brain axis. The connection between gut environment and brain may affect host mood and behaviors. Disruptions in microbial communities have been implicated in several neurological disorders. A link between the gut microbiota and the brain has long been described, but recent studies have started to reveal the underlying mechanism of the impact of the gut microbiota and gut barrier integrity on the brain and behavior. Here, we summarized the gut barrier environment and the 4 main gut-brain axis pathways. We focused on the important function of gut barrier on neurological diseases such as stress responses and ischemic stroke. Finally, we described the impact of representative environmental sensors generated by gut bacteria on acute neurological disease via the gut-brain axis.

• 한국환경교육학회지:환경교육
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• 제24권2호
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• pp.54-69
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• 2011

The objectives of this study were to investigate the need for school uniform recycling and to review the school uniform recycling-related education. 231 female high school students were asked to answer regarding the wearing state of school uniform and their satisfaction level. 10 subjects in middle school technology/home economy were evaluated. As the result, the students wore 1~2 pieces of school uniform, which showed that it was hard to keep them clean by washing them often. The satisfaction level of school uniform was not high, The lowest item was the price. Therefore, to increase the satisfaction level of the school uniforms and also to increase the sanitary level of the school uniforms, it was advisable to purchase a recycled school uniform at cheaper prices to have an extra set. For a vitalization of the recycled school uniforms, the middle school technology/home economy subjects were reviewed. In the topic of "clothing acquisition plan and purchase", the themes of planned purchase, overconsumption of clothing and environmental pollution were discussed and included preferable behaviors for disposal. The topic of "clothing manufacturing and recycling" listed recycling the clothes that are not worn or exchanging them with neighbors as well as suggesting methods to illicit environment-friendly behaviors and carrying them out. However, some textbooks only briefly explained the methods of recycling and more detailed and practical methods need to be suggested in the curriculum. In addition, the contents regarding the environment in the clothing topic need to be supplemented more and more changes, such as related education plans or data development, are required. The objectives of this study were to investigate the need for school uniform recycling and to review the school uniform recycling-related education. 231 female high school students were asked to answer regarding the wearing state of school uniform and their satisfaction level. 10 subjects in middle school technology/home economy were evaluated. As the result, the students wore 1~2 pieces of school uniform, which showed that it was hard to keep them clean by washing them often. The satisfaction level of school uniform was not high, The lowest item was the price. Therefore, to increase the satisfaction level of the school uniforms and also to increase the sanitary level of the school uniforms, it was advisable to purchase a recycled school uniform at cheaper prices to have an extra set. For a vitalization of the recycled school uniforms, the middle school technology/home economy subjects were reviewed. In the topic of "clothing acquisition plan and purchase", the themes of planned purchase, overconsumption of clothing and environmental pollution were discussed and included preferable behaviors for disposal. The topic of "clothing manufacturing and recycling" listed recycling the clothes that are not worn or exchanging them with neighbors as well as suggesting methods to illicit environment-friendly behaviors and carrying them out. However, some textbooks only briefly explained the methods of recycling and more detailed and practical methods need to be suggested in the curriculum. In addition, the contents regarding the environment in the clothing topic need to be supplemented more and more changes, such as related education plans or data development, are required.