Ching-Mu Chen

Development of a universal contactless charger for handheld devices

The purpose of this paper is to design and implement a universal contactless charger for handheld device by means of electromagnetic coupling induction related applications. Through coil coupling induction, contactless power transmission system is able to supply power to the secondary side with high safety and low repair rate features. However, this paper discusses PCB (Printed Circuit Board) and a spiral-type induction coil used as a coupling induction device for the contactless charging system. With the design proposed in this paper, the size of regular counting induction devices can be greatly reduced. By changing the geometric shape and location of coupling coil, the relationship and changing conditions of respective parameters and coupling coefficients can be obtained and analyzed to serve as references for future designs. Therefore, in conjunction with theoretic and actual design guidelines, sequential studies will be conducted. Finally, contactless mobile phone charger with rated 4.2V, 800 mA is completed to validate its function.

An efficient data aggregation scheme for grid-based wireless sensor networks

Wireless sensor networks (WSNs) have cost-effective, easy deployment, and ad-hoc function. Sensor nodes have the characteristics of low-power, small sensors with limited computation capabilities, and low-cost. In this paper, a dual-tree-based data aggregation (DTDA) scheme for grid-based WSNs is proposed. The proposed DTDA is based on dual-tree structure. The goal is to establish dual trees (a dual-tree) that have an approximate number of nodes for data aggregation. DTDA provides two paths between roots and sinks. It minimizes energy consumption and evenly distributes load to prolong network lifetime. Simulation results show that the proposed DTDA outperforms CODE and DARQ.

An Efficient Forward and Backward Fault-Tolerant Mobile Agent System

Mobile agent is a special program and it can switch and execute the task of user commands among the networks and hosts. During the task executing, the mobile agent can convey the data, state and program code to another host in order to autonomously execute and continue the task in another host. While the mobile agent is executing the task at any of the software and hardware fault incurred or network problems, there will be two conditions as following lists: 1. Users continuously wait the reply from the agent, but users will never have the reply because of the some faults incurred to the agent in the networks or hosts. 2. Users assign a new agent as the former agent has been lost to restart the former task, but the former agent only congested the delay problem of the network or host. This causes that these two agents have the same task to be executed. Therefore, the fault detecting and recovering of the mobile agent are important issues to be discussed. However, this paper propose a front behind failure detection and recovery method that the task agent has to report the task process at the present stage to the former and latter agent and agents will exchange their messages for the present stage. This is more accurate than the method in for the task at present because it can reduce the loading of the task fault report from the network congested.

Gender activities in mobile internet

With the rapid growth of demands of mobile phones, and the advent of third generation technology, accessing Internet via mobile phones is going to become the most promising trend. However, the success of mobile Internet (m-Internet) implementation depends on whether or not individuals are willing to adopt this new technology. Thus, it is necessary for practitioners and academics to explore the factors influencing the acceptance of m-Internet by individuals. By analyzing the data, results indicate that that performance expectancy, effort expectancy, social influence, perceived value and palm-sized computer self-efficacy were significant determinants of behavioural intention to use m-Internet. We also found that gender activities moderate the effects of performance expectancy, effort expectancy and palm-sized computer self-efficacy on m-Internet usage intention. These findings offer several important implications for m-Internet acceptance, in terms of both research and practice.

Performance of a data gather scheme with novel chain construction for wireless sensor networks

The energy efficiency and balancing energy dissipation are important issues for the data gather schemes in WSNs. In this paper, we propose Grid-PEGASIS to improve the performance of chain-based scheme on these two issues. The proposed Grid-PEGASIS divides the sensing area into several small Grid areas to reduce the hop variance of a sensing area chain. With the smallest hop variance, Grid-PEGASIS balances the energy consumption for nodes. Approximated analysis and simulation results show that the Grid-PEGASIS can largely prolong the network lifetimes of the first 1%, 5% and 25% nodes running out of energy.

Application of Universal Contactless Charger for Cellular Phone

This paper discusses the designation and implementation of a universal contactless charger for a Cellular phone. By using the electromagnetic coupling induction with the related applications, the charger can be done. Through the coil coupling induction, contactless power transmission system can supply the power to the secondary side with higher safet rate and lower repair probability. However, the application discuused in this paper is the PCB (Printed Circuit Board) and a spiral-type induction coil used as a coupling induction device for the contactless charging system. With the design scheme in this paper, the size of regular counting induction devices can be greatly reduced. By changing the geometric shape and location of coupling coil, the relationship and changing conditions of respective parameters and coupling coefficients can be obtained and analyzed to serve as references for future designs. Therefore, in conjunction with theoretic and actual design guidelines, sequential studies will be conducted. Finally, contactless Cellular phone charger with rated 4.2V, 800 mA is completed to validate its function.

Battery Management for a Contactless Charger

This paper designs a contactless charger using the two-way battery charging that is the constant voltage (CV) and the constant current (CC). The charger system in this paper includes a microprocessor to manage the charge and discharge of the charger and predict the battery volume and low-battery warning. This system prevents the battery from over-charge and over-discharge. damage. The primary side of the transformer has maximum output is about 290W and the secondary side of the transformer is able to induct 124W at 1 cm coupling distance through air gap radiation. The maximum current is over 5.5A and the efficient transmission rate is over 41%.

Fault tolerance of connectivity performance in CDMA-based wireless sensor networks

In this paper, we investigate the fault tolerance of connectivity probability for CDMA-based wireless sensor networks with variations of nodes deployment. The variations of deployment are modeled by 2D Gaussian distribution with zero-mean for the triangle, grid and hexagon topologies. Thus, the k-connectivity performance is studied through the outage probability of CDMA signal links. We evaluate the connectivity performance with SIR0,3-con, the minimum requirement of SIR, SIR0 for the 3-connectivity, when the nodes suffer a failure rate Pf. Simulation results show that the hexagonal and grid topologies suffer a degradation of -2.4 and -0.5 dB, respectively, when the failure rate Pf equals 0.1. However, the triangular topology shows robust fault tolerance with the failure rate Pf below 0.5 and moderate variations of deployment.