Papers by Author: Hyun Su Kim

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Authors: Yoon Suk Chang, Hyun Su Kim, Tae Eun Jin
Authors: Sung Gyu Jung, In Gyu Park, Chang Soon Lee, Hyun Su Kim, Tae Eun Jin
Abstract: Reactor pressure vessel (RPV) is the most critical component in nuclear power plant. RPV is subjected to radiation embrittlement, which is characterized as neutron fluence-dependent reduction in fracture toughness of the material. Therefore, risk for potential failure of RPV increases as operating time and fluence level increase. To prevent the potential failure, it is requested for RPV to operate in accordance with pressure-temperature (P-T) limit curve during operation. However, it has been reported that P-T limit curve which is typically developed in accordance with the procedure in ASME code is too conservative. Therefore, in order to investigate the conservatism of current P-T limit curve and develop more realistic one, probabilistic approach based on the risk was utilized in this paper. The resulting P-T limit curve is very higher than that from deterministic approach, and can be used as alternative operation limit of the RPV, because probabilistic P-T limit curve seems to have enough safety margin for potential failure of RPV.
Authors: Hyun Mi Pyo, Jie Yun Park, Sue Nie Park, Hyun Su Kim, Kee Sun Shin, Har Young Poo
Abstract: The development of a human papillomavirus vaccine has received a lot of recent attentiondue to the connection between HPV infections and cervical cancer. One promising vaccine to prevent HPV infections is an HPV virus-like particle, and various studies have already shown that HPV VLP immunization elicits a humoral immune response. However, cell mediated immunity is important for the prevention of HPV infections and cancer therapy. Therefore, to check the elicitation of a CTL response by yeast-derived virus- like particles consisting of the HPV16 capsid protein L1, HPV16 L1 VLPs were produced and purified, then C57BL/6 mice immunized with the HPV16 L1 VLPs by subcutaneous injection. Thereafter, the splenocytes from the immunized mice were isolated and a chromium release assay performed using recombinant B16/HPV16 L1cells constantly expressing the HPV16 L1 protein. As a result, the data demonstrated that the T cells from the HPV16 L1 VLP immunized mice exhibited a significantly higher cytotoxic T lymphocyte activity against the recombinant B16/HPV16 L1 cells than the T cells from the PBS immunized control mice.
Authors: J.K. Park, Hyun Su Kim, D.Y. Kim
Authors: Hyun Su Kim, Tae Eun Jin, Hong Deok Kim, Han Sub Chung, Yoon Suk Chang, Young Jin Kim
Abstract: Steam generator in a nuclear power plant is huge heat exchanger that transfers heat from reactor to make steam to drive turbine-generator. Failure of the steam generator tubes can result in the release of fission products to the secondary side. Therefore, accurate integrity assessment of the cracked steam generator tubes is of great importance for maintaining the safety of the nuclear power plant. This paper provides limit loads for circumferential through-wall cracks in steam generator tubes under combined internal pressure and bending loads. Such limit loads are developed on the basis of three dimensional finite element analyses assuming elastic-perfectly plastic material behavior. As for the crack location, both the top of the tubesheet and U-bend regions are considered. The analysis results can be directly applied to the practical integrity assessment of cracked steam generator tubes, because the comparison between experimental data and FE results shows a very good agreement.
Authors: Hyun Su Kim, Jong Sung Kim, Tae Eun Jin, Hong Deok Kim, Han Sub Chung
Authors: Ouk Sub Lee, Hyun Su Kim, Jong Sung Kim, Tae Eun Jin, Hong Deok Kim, Han Sub Chung
Abstract: Operating experience of steam generators has shown that cracks of various morphologies frequently occur in the steam generator tubes. These cracked tubes can stay in service if it is proved that the tubes have sufficient safety margin to preclude the risk of burst and leak. Therefore, integrity assessment using exact limit load solutions is very important for safe operation of the steam generators. This paper provides global and local limit load solutions for surface cracks in the steam generator tubes. Such solutions are developed based on three-dimensional (3-D) finite element analyses assuming elastic-perfectly plastic material behavior. For the crack location, both axial and circumferential surface cracks, and for each case, both external and internal cracks are considered. The resulting global and local limit load solutions are given in polynomial forms, and thus can be simply used in practical integrity assessment of the steam generator tubes, because the comparison between experimental data and FE solutions shows good agreement.
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