The purpose of this paper is to analyze the seismic response effect caused by the mass eccentricity of individual equipment when conducting base isolation for the improvement of the seismic performance of a nuclear power plant. Recent research has interpreted and confirmed through analysis and testing that base isolation for safety-related equipment in nuclear power plants is an efficient alternative to designing for excessive seismic loads. Depending on the equipment, unavoidable mass eccentricity can occur, which necessitates verification of the response impact caused by eccentricity. In this paper, we analyze the seismic response impact of equipment with mass eccentricity using small base isolators. To do so, sensitivity analysis of the seismic response due to mass eccentricity is conducted for a base-isolated concentrated mass model. Furthermore, three efficient mass eccentricity models suitable for testing are designed and manufactured. Simulation analyses using the finite element method (FEM) models are performed, followed by three-axis shake table tests to validate the seismic response impact of mass eccentricity. In conclusion, it is confirmed that applying small base isolators to equipment with mass eccentricity can affect seismic response impact to some extent when compared for a beyond-design-basis earthquake (BDBE).

레졸형 페놀수지에 탄소계 나노필러인 그래핀 옥사이드(GO)와 다중벽 탄소나노튜브(MWCNT)를 0.1 wt% 이하로 첨가하여 페놀수지 폼을 제조하였으며 셀 크기, 셀 구조, 기계적 성질, 열적 성질, 음향학적 성질에 미치는 영향을 고찰하였다. 제조된 모든 페놀수지 폼들은 육각형의 닫힌 셀 구조를 형성하였으며, GO와 MWCNT를 포함하는 페놀수지 폼들은 굴곡 하중에서 순수 페놀수지 폼(control)보다 취성 파괴에 대한 높은 저항성을 나타내었다. MWCNT를 포함하는 페놀수지 폼들은 필러를 첨가하지 않은 순수 페놀수지 폼보다 작은 셀을 형성하였으며 굴곡하중 하에서 향상된 취성을 가졌다. 0.1 wt%의 GO나 MWCNT를 포함하는 페놀수지 폼은 순수 페놀수지 폼보다 2배 이상의 높은 열전도도를 나타내었으며, 저주파음과 고주파음의 차단에 효과적이었다. 필러를 첨가한 페놀수지 폼 중에서 MWCNT를 포함하는 페놀수지 폼이 500~4000 Hz 영역에서 가장 높은 흡음계수를 보였다.

The tumor microenvironment contains distinctive biomarkers, including acidic pH, elevated levels of reactive oxygen species (ROS), and hypoxia, necessitating the development of efficient biosensors for simplified cancer detection. This study presents an O₂-responsive hydrogel biosensor composed of [1,1′-biphenyl]-2,2′,4,4′,5,5′-hexaol (HDP) and polyvinyl alcohol (PVA) that exploits polyphenol-mediated interactions under N₂ and O₂ microenvironments. The oxidative susceptibility of the polyphenolic HDP moiety influences its distinct mechanical, physical, and electrochemical properties, allowing the differentiation between cancerous and normal cells. The in vitro assessments with cancer cell lines (HeLa and B16F10) and normal cell lines (CHO-K1) enabled distinctive electrical and mechanophysical outputs, as evidenced by enhanced mechanical compressive modulus and high conductivity, regulated by normoxic cellular states. In addition, the inherent ROS-scavenging capability of the HDP–PVA hydrogel sensor supports its potential application in hypoxia-related diseases, including cancer.

This paper aims to examine the validity of applying individual seismic isolation technologies to small facilities or equipment, such as safety-related cabinets within domestic operating nuclear power plants, to enhance their seismic performance. Generally, applying seismic isolation technology to older nuclear power plant buildings poses significant technical and cost burdens. Therefore, a recent approach has been to first check the seismic performance of major equipment with high safety importance through probabilistic seismic analysis and select those with insufficient performance to improve their seismic capabilities. In this paper, among the equipment requiring seismic performance improvement, we focus on applying device isolation to Load Center (LC) cabinets and analyze the effectiveness of seismic performance enhancement against beyond design basis earthquakes (BDBE). To achieve this, we first conduct modal analysis through finite element modeling of the target equipment and then model it as a concentrated mass type with similar dynamic characteristics. We calculate the maximum response under BDBE by applying fixed conditions and two types of isolation conditions. Furthermore, we validate the analytical results through a 3D shaking table test on a physical model equipped with small seismic isolation bearings developed in previous studies. As a result, it is confirmed that applying seismic isolation technology individually to safety-critical equipment, such as Load Center cabinets, can also be a viable alternative for improving seismic performance.