• 한국도로학회논문집
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• 제18권2호
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• pp.43-49
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• 2016

PURPOSES : The field application and performance of continuously reinforced concrete pavement (CRCP), constructed by using the mechanical tube-feeding method, are evaluated in this study. METHODS: The location of the rebar was evaluated by using the MIRA system. The early-age CRCP performance was evaluated via visual survey, in which the crack spacing and crack width were examined. RESULTS: The location of longitudinal reinforcing bars was evaluated via MIRA testing and the results showed that the longitudinal rebars all lie within a given tolerance limit (${\pm}2.5cm$) of the target elevation. In addition, owing to the low temperature when the concrete was pured, the crack spacing in the Dae-Gu direction is slightly wider than that of the Gwang-Ju direction. Almost all of the crack spacings lay within the range of 1.0 m~3.0 m. A crack width of <0.3 mm was measured at the pavement surface. However, as revealed by the field survey, the crack spacing was not correlated with the crack width. CONCLUSIONS : In CRCP constructed by using the mechanical tube-feeding method, almost all of the longitudinal reinforcing bars lay within the tolerance limit (2.5 cm) of the target elevation. The concrete-placing temperature affects the crack spacing, owing to variations in the zero-stress temperature. Crack survey results show that there is no correlation between the crack spacing and crack width in CRCP.

• 소성∙가공
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• 제25권3호
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• pp.176-181
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• 2016

The exhaust tail pipe is the only visible part of the exhaust system on a vehicle. The conventional way to make the tail pipe is welding after stamping. There are various problems that occur during the stamping of stainless steel sheets such as scratching and local fracture. Problems during welding can also occur due to poor weldability. Tube hydroforming can be a solution, which eliminates these problems. The current study deals with the development of tube hydroforming for a vehicle tail pipe using finite element analysis for a free-feeding method. The current study focuses on the development of a proper load path for the tail pipe hydroforming and how bending influences the subsequent processing steps. The FE analysis results were compared with experimental results. This study shows the importance of bending and the necessity of considering bending when performing a tube hydroforming analysis.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.642-647
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• 2007

Determination of loading conditions for tube hydroforming(THF) process that implies an amount of the increment in axial feeding and internal pressure for each step is one of the most important constituents at the process design level. On account of the fact that those design factors mentioned above are imposed simultaneously during the process, suitable loading conditions are required to obtain robust products without any failure such as buckling, necking, bursting and so on. In which, especially, bursting is well known as the most frequently occurred failure in general THF process. In this study, therefore, determination of the loading condition based on the adaptive method was carried out to obtain safe loading paths. In addition, forming limit curves are applied to evaluate the derived loading conditions by using the simulation results. Consequently, it is found that described method in this study for THF process design is useful and has a feasibility.

• Child Health Nursing Research
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• 제18권1호
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• pp.9-18
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• 2012

Purpose: This study was conducted to analyze factors affecting readmission of children with home ventilator care. Methods: To collect patient data, a retrospective chart review was done of medical records of children admitted between June 1, 2007 and May 31, 2010 at one children's hospital located in Seoul. During that period 30 children were discharged with a home ventilator. Results: Twenty-one of these children had a total of 63 readmissions during the study period, averaging 2.1 readmissions per child with a mean duration of hospitalization of 7.4 days. Children with nasogastric tubes were more frequently readmitted (t=7.232, p=.012) and duration of hospitalization was significantly longer (t=4.761, p=.038). Children who had cardio-pulmonary comorbidity were more frequently readmitted and had longer hospitalization than children without comorbidity (t=5.444, p=.027). When home ventilator assisted children were admitted via emergency room, they were hospitalized longer (t=14.686, p=<.001). Cardio-pulmonary morbidity and readmission via ER explained 38.1% of variation for readmission. Feeding method explained 15.0% of variation in length of hospitalization. Conclusion: The results suggest that health care providers must give individualized education on home ventilator care to parents with children who are at risk for readmission due to cardio-pulmonary comorbidities, nasogastric tube, or readmission via ER.