In this paper, a mobile quiz system using SMS has been developed, which can be conveniently used on the spot of education. The system immediately not only provides each individual student with the results of his/her quizzes but also a instructor with the statistics of the results by SMS. Field tests of the quiz system have shown that it can be effectively used as a good teaching tool for teachers getting immediate feedback from participants in the lecture and adjusting teaching level as well as for inducing more interest in learning from participants and raising their concentration on the class.

A home network gateway has been developed, which supports both wire and wireless communication functions. ZigBee and PLC modules are taken as communication hardware and a conversion protocol is implemented to be able to smoothly exchange the information between the two hardware modules. The developed gateway shows good performance and can supports various home network service configurations.

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DVR is widely used in the security monitoring system because it has excellent performance compared with VCR. In this paper, the new DVR interfaces and repeaters enhancing the performance of the existing DVR have been designed and implemented, which enables a large-scaled security monitoring system to be built economically. A repeater in this paper connects 8 monitoring terminals to 2 channels of DVR and a DVR interface manages 16 repeaters to be able to accommodate 128 monitoring terminals. Eventually, the implemented system has a quadruple scalability compared to the existing systems and can reduce the installation cost substantially by using cost-effective UTP cables instead of coaxial cables. And the system could be effectively used in various environments and conditions because various functions such as video transmission, audio communication, emergency call, and RFID card are integrated into the system.