Sungkeun Baang

Hybrid positioning with lighting LEDs and Zigbee multihop wireless network

A simple, accurate, secure, long-lasting, and portable hybrid positioning system is proposed and designed in this paper. It consists of a lighting LED that generates visible light data corresponding to position information of a target and a Zigbee wireless network communication module with low power, security, and service area expansion characteristics. Under an indoor environment where there is 23.62m distance between an observer and the target, the presented hybrid positioning system is tested and is verified with the functions of Zigbee three hop wireless networking and visible light communication (VLC) scheme. The test results are analyzed and discussed.

Realization of Non-carrier Visible Light Communication System based upon LED IT

In this paper, as a study of the simple visible light communication(VLC) with LED light, the visible light communication system that are made up with the white LED array for visible light transmission, various photodiodes for visible light reception, and a non-carrier NRZ-OOK modulation scheme is designed and implemented to have a 115.2 kbps data speed at 2.5 m distance between transmitter and receiver. For the performance analysis of the developed VLC system, the maximum distance between VLC transmitter and receiver on the conditions of various transmission speeds, the number of LED array, or the various kind of LED and photodiode is obtained, and various performances are analyzed by experiments.

Signal Modeling with Random Scatterers for Confocal Microwave Imaging

Microwave breast tumor detection uses the electrical property contrast between normal tissues and malignancies to detect the latter in an early development stage. However, previous works on the microwave imaging uses 2-D or more complicated models of the breast and electromagnetic wave propagation. We present a computationally efficient and physically instructive electromagnetic wave channel modeling for confocal microwave imaging system for the breast tumor detection. The proposed model covers all of the factors that have been examined in the previous 2-D model, such as the radial spreading, path loss, partial reflection and transmission of the backscattered electromagnetic wave from the tumor cell. The characteristics of the reconstructed images of the tumor using the proposed 1-D model are compared with them of the previous 2-D FDTD method. Previous 2-D model of the cancerous breast utilizes the MRI-derived discretized cell model to simulate the realistic perturbation, but there has been no consideration on the system noise that can be detrimental to the reconstruction of the tumor. The effect of the system noise level to the reconstruction algorithm will be addressed as well