The ammonia leaching tests were carried out to recover valuable metals from alloy obtained from smelting reduction process of mobile phone printed circuit boards. Leaching factors such as kinds of salt, ammonia concentration, and the interaction of metals, which are components of PCB, were investigated to improve the leaching efficiency. In the leaching tests using metal powders such as Zn, Sn, Ni, and Pb to investigate the interaction of metals, zinc was easily dissolved in ammonia solution, whereas Sn and Ni were not detected or the Pb concentration decreased rapidly. The metal concentrations increased with an increase in NH 3 concentration from 1 to 5 kmol m 23 . The content of Cu could increase to 98% under the leaching conditions: 2 kmol m 23 NH 4 Cl and 5 kmol m 23 NH 3 solution with 0.1 kmol m 23 CuCl 2 at 200 rpm and 308C with 1% pulp density.
SUMMARYWith the proliferation of smart grids and the construction of various electric IT systems and networks, a next-generation substation automation system (SAS) based on IEC 61850 has been agreed upon as a core element of smart grids. However, research on security vulnerability analysis and quantification for automated substations is still in the preliminary phase. In particular, it is not suitable to apply existing security vulnerability quantification approaches to IEC 61850-based SAS because of its heterogeneous characteristics. In this paper, we propose an IEC 61850-based SAS network modeling and evaluation approach for security vulnerability quantification. The proposed approach uses network-level and device groupings to categorize the characteristic of the SAS. In addition, novel attack scenarios are proposed through a zoning scheme to evaluate the network model. Finally, an MTTC (Mean Time-to-Compromise) scheme is used to verify the proposed network model using a sample attack scenario.
SUMMARYPower line communication (PLC) is an evolving technology which uses existing power lines for data transmission. Like any other communication network, PLC networks need to be managed to ensure effi cient use of resources and secure operations. Currently, major PLC chip vendors are trying to provide network management solutions based on the Simple Network Management Protocol (SNMP) by developing their own management systems, but they cannot manage heterogeneous PLC networks comprised of PLC devices from various PLC chip vendors. In this paper, we provide our experience of developing and testing an integrated management system for a heterogeneous PLC network based on SNMP. We present our approach for integrated management by defi ning the common PLC management information base (MIB) and an integrated PLC proxy agent for providing interoperability to legacy PLC devices which do not support the common PLC MIB. We also present the development of an integrated PLC network management system and its test in heterogeneous PLC networks deployed in South Korea. The contribution of our work is to provide a guideline for developing and testing integrated NMSs for any heterogeneous networks including PLC networks.
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