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30 results on '"Kang, Youn-Hee"'

7. An Infrared Local-Heat-Assisted Cold Stamping Process for Martensitic Steel and Application to an Auto Part

Author

Hyoun-Young Lee, Kim Kisoo, Chang Ho Moon, Eun-Ho Lee, Kang Youn-Hee, Ki Young Kim, Jong-Youn Park, and Soo-Hyun Park

Subjects
lcsh:TN1-997, 0209 industrial biotechnology, Materials science, local heat treatment, formability, infrared heating, Automotive industry, 02 engineering and technology, door impact beam, springback, 020901 industrial engineering & automation, Formability, General Materials Science, Infrared heater, Ductility, lcsh:Mining engineering. Metallurgy, martensitic steel, business.industry, Metallurgy, Metals and Alloys, Forming processes, Stamping, 021001 nanoscience & nanotechnology, Microstructure, Martensite, 0210 nano-technology, business
Abstract

The automotive industry has tried to employ ultra-high-strength steel (UHSS), which has a higher strength with a thinner thickness. However, because of its low formability, there is a limit to the use of UHSS in industrial applications. Even though the hot-press-forming method can resolve the formability problem, elevated-temperature conditions lead to side effects—heat transfer and productivity issues. This work presents the concept of an infrared local-heat-assisted cold stamping process. Before the forming process, local areas, where the formability problem occurs, are locally heated by the gathering of infrared rays and cooled to room temperature before delivery. Since the heat treatment is completed by the material supplier, the stamping companies can conduct cold stamping without new investments or the productivity issue. In this work, a heat-assisted cold V-bending test was conducted with a martensitic (MS) 1.5 GPa steel, the CR1470M steel provided by POSCO. The heating effects on the microstructure, hardness, and local ductility were also observed. Finally, a commercial door impact beam was successfully manufactured with the present method. In this application, only a targeted small area was heated. The results show that the present method can improve the formability and springback problems of MS steel in the stamping process.

Published
2020

14. A review of research and strategies for burnout among Chinese nurses

Author

Wu Dong, Kang Youn Hee, and Wang Lei

Subjects
China, Personnel Administration, Hospital, Nursing staff, business.industry, health care facilities, manpower, and services, education, Stressor, MEDLINE, Burnout, Nursing Staff, Hospital, Nurse's Role, Nursing, Risk Factors, health services administration, Health Facility Environment, Medicine, Humans, business, Burnout, Professional, psychological phenomena and processes, General Nursing
Abstract

Although the concept of burnout has been a significant nursing issue worldwide over the past 30 years, in China the relevant research about nursing burnout only started in the 1990s. In this time, nursing burnout has become increasingly prevalent. This article examines the research carried out both in China and internationally, in order to investigate the causes of stress that lead to burnout among nurses. With the key stressors identified, the article sets out a proposal for a programme to alleviate the stress of hospital nurses and help them to engage with their jobs

Published
2010

30. One-Dimensional Semiconductor Nanostructure Based Thin-Film Partial Composite Formed by Transfer Implantation for High-Performance Flexible and Printable Electronics at Low Temperature

Author

Moon, Kyeong-Ju, Lee, Tae-Il, Choi, Ji-Hyuk, Jeon, Joohee, Kang, Youn Hee, Kar, Jyoti Prakash, Kang, Jung Han, Yun, Ilgu, and Myoung, Jae-Min

Abstract

Having high bending stability and effective gate coupling, the one-dimensional semiconductor nanostructures (ODSNs)-based thin-film partial composite was demonstrated, and its feasibility was confirmed through fabricating the Si NW thin-film partial composite on the poly(4-vinylphenol) (PVP) layer, obtaining uniform and high-performance flexible field-effect transistors (FETs). With the thin-film partial composite optimized by controlling the key steps consisting of the two-dimensional random dispersion on the hydrophilic substrate of ODSNs and the pressure-induced transfer implantation of them into the uncured thin dielectric polymer layer, the multinanowire (NW) FET devices were simply fabricated. As the NW density increases, the on-current of NW FETs increases linearly, implying that uniform NW distribution can be obtained with random directions over the entire region of the substrate despite the simplicity of the drop-casting method. The implantation of NWs by mechanical transfer printing onto the PVP layer enhanced the gate coupling and bending stability. As a result, the enhancements of the field-effect mobility and subthreshold swing and the stable device operation up to a 2.5 mm radius bending situation were achieved without an additional top passivation.

Published
2011
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