• 대한임베디드공학회논문지
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• 제6권3호
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• pp.190-200
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• 2011

Android platform provides a content provider and a cursor mechanism to access the internal SQLite engine. Content providers not only store and retrieve data but also make it accessible to applications. Applications can only share data through content provider, since there's no common storage area that Android packages can access. Cursor is an interface that provides random read-write access to the result set returned by a database query. However, this cursor possesses two major limitations. First, a cursor does not support a join clause among cursors, since the cursor can only access a single table in the content provider. Second, the cursor is not capable of creating user-customized field in the predefined content providers. In this paper, we propose the unified cursor architecture that merges several cursors into a single virtual cursor. Cursor translation look-aside buffer (TLB), column windowing mechanism and virtual data management are the three major techniques we have adopted to implement our structure. And we also propose a delayed synchronization method between an application and a proposed unified cursor. An application can create a user-customized field and sort multiple tables using a unified cursor on Android platform.

• Journal of Advanced Marine Engineering and Technology
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• 제40권10호
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• pp.906-915
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• 2016

In this study, a network monitoring system, including a secure 460-Network and a 460-Gateway, is designed and developed according with the requirements of the IEC (International Electro-Technical Commission) 61162-460 network standard for the safety and security of networks on board ships. At present, internal or external unauthorized access to or malicious attack on a ship's on board systems are possible threats to the safe operation of a ship's network. To secure the ship's network, a 460-Network was designed and implemented by using a 460-Switch, 460-Nodes, and a 460-Gateway that contains firewalls and a DMZ (Demilitarized Zone) with various application servers. In addition, a 460-firewall was used to block all traffic from unauthorized networks. 460-NMS (Network Monitoring System) is a network-monitoring software application that was developed by using an simple network management protocol (SNMP) SharpNet library with the .Net 4.5 framework and a backhand SQLite database management system, which is used to manage network information. 460-NMS receives network information from a 460-Switch by utilizing SNMP, SNMP Trap, and Syslog. 460-NMS monitors the 460-Network load, traffic flow, current network status, network failure, and unknown devices connected to the network. It notifies the network administrator via alarms, notifications, or warnings in case any network problem occurs. Once developed, 460-NMS was tested both in a laboratory environment and for a real ship network that had been installed by the manufacturer and was confirmed to comply with the IEC 61162-460 requirements. Network safety and security issues onboard ships could be solved by designing a secure 460-Network along with a 460-Gateway and by constantly monitoring the 460-Network according to the requirements of the IEC 61162-460 network standard.