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Seulki Hwang,Daesup Hwang,Hani Baek,Chansun Shin 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7
A spring beam in a miniature electrical switch enables the two electrical contacts to either close or separate and suppliesboth current and necessary contact pressure between the contacts. Arc erosion and material transfer between the contactsoccur, and those aspects depend on various parameters including the kinematics of the contacts. Therefore, the mechanicalproperties of the spring beam will affect the arc erosion and material transfer, but this topic has not been well studied. In thisstudy, the material transfer phenomena between two AgCu contacts attached to a spring beam made of three different copperbasedstrip alloys were investigated after 30,000 switching operations under 12 V and 9 A in a direct-current resistive loadcircuit. For spring beams made of beryllium copper (BeCu) and titanium copper (TiCu) alloy, the material transfer occurredfrom the cathode to the anode. However, an opposite material transfer occurred for a spring beam made of Corson-type(CuNiSi) alloy. The make- and break-arc voltage waveforms were analyzed, and the results showed that the changes in arcingbehaviors depend on the spring beam material. The properties of the spring beam materials responsible for the changedarcing behaviors are discussed and their relationship with the observed contact arc erosion and material transfer is analyzed.
Sun, Gwang Min,Lee, Jaegi,Uhm, Young Rang,Baek, Hani Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.11
Boron has been considered to play a nutritionally important role in humans and animals, but its biochemical functions are not clearly understood. Though there are signs that boron affects the mineral and hormone metabolisms, there is no comprehensive epidemiological evidence establishing a relationship between a boron intake and osteoporosis due to the excretion of calcium in the bones. In this study, we investigated the influence of boron intake on the calcium excretion of old female mice in the menopause. The concentrations of calcium in backbone, thigh bone, blood, kidney, liver, and spleen were investigated by using instrumental neutron activation analysis.