Enhanced thermal properties of the solid electrolyte interphase formed on graphite in an electrolyte with fluoroethylene carbonate

The influence of fluoroethylene carbonate (FEC) on the electrochemical and thermal properties of graphite anodes is examined. The dQ/dV graph of graphite/Li cells shows that the electrochemical reduction peak of an electrolyte shifts to higher potential in the presence of FEC. The DSC results for graphite anodes cycled in FEC-containing electrolytes clearly exhibit that an exothermic peak at around 120 °C mostly disappears. It is demonstrated by X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) that SEI formed by the electrochemical reduction of FEC consists of a relatively high proportion of LiF and gives low interfacial resistance for graphite/Li/Li cells.     

MEA design for low water crossover in air-breathing DMFC

The water crossover behavior in air-breathing direct methanol fuel cell (DMFC) was studied with varying structural variables of membrane electrode assembly (MEA), such as existence of microporous layer (MPL) in cathode diffusion layer, hydrophobicity of cathode backing layer, and membrane thickness. Water crossover from anode to cathode was lowered by the introduction of MPL to cathode backing layer, the reduction of hydrophobicity of cathode backing layer, and the reduction of membrane thickness. To account for the observed water crossover behavior, water back flow caused by the hydraulic pressure difference between the cathode and anode was considered. It was also found that the methanol crossover was lowered with the reduction of water crossover. The MEA designed for low water crossover revealed improved stability under continuous operation.     

Dangerous Wi-Fi access point: attacks to benign smartphone applications

Personalization by means of third party application is one of the greatest advantages of smartphones. For example, when a user looks for a path to destination, he can download and install a navigation application with ease from official online market such as Google Play and Appstore. Such applications require an access to the Internet, and most users prefer Wi-Fi networks which are free to use, to mobile networks which cost a fee. For this reason, when they have no access to free Wi-Fi networks, most smartphone users choose to try to use unknown Wi-Fi access points (AP). However, this can be highly dangerous, because such unknown APs are sometimes installed by an adversary with malicious intentions such as stealing information or session hijacking. Today, smartphones contains all kinds of personal information of the users including e-mail address, passwords, schedules, business document, personal photographs, etc., making them an easy target for malicious users. If an adversary takes smartphone, he will get all of information of the users. For this reason, smartphone security has become very important today. In wireless environments, malicious users can easily eavesdrop on and intervene in communication between an end-user and the internet service providers, meaning more vulnerability to man-in-the-middle attacks. In this paper, we try to reveal the risk of using unknown APs by presenting demonstration results. The testbed is composed of two smartphones, two APs, and one server. The compromised AP forwards messages of victim smartphone to the fake server by using domain name system spoofing. Thus, the application that is running on the victim smartphone transfers HTTP request to the fake server. As a result, this application displays the abnormal pop-up advertisement, which contains malicious codes and links. Our demonstration shows that merely connecting to compromise APs can make a malicious behavior even the applications are benign.     

Implementation of a cost-effective home lighting control system on embedded Linux with OpenWrt

In recent years, the significance of greenhouses has been increased greatly because the world has been facing serious problems with energy as its growing demand. At the same time, home automation systems have been steadily gaining popularity; growing toward smart home based on Cloud technology. This paper introduces a cost-effective home energy saving system based on a small embedded system with remote controlling feature. For this purpose, the system is composed of a wireless router based on embedded Linux for the platform to develop a low-cost energy control server and a smart phone for remote light control app. The prototype system was implemented by porting OpenWrt onto the wireless router which is connected with an interface board with LEDs attached. The remote access and GUI function were implemented by TCP/IP programming using Apple iPhone. The operation of the remote control system was verified by socket communication between the smart phone and the wireless router, and by USB communication between the wireless router and the interface board. The implementation result shows that an OpenWrt-based wireless router can give benefits of saving energy and safety through lighting control.     

Enhancement of two-factor authenticated key exchange protocols in public wireless LANs

In 2008, Juang and Wu proposed two authenticated key exchange protocols by improving Park and Park’s two-factor authenticated key exchange protocol in public wireless LANs. They pointed out that Park’s protocol was vulnerable to the dictionary attack on the identity protection. The improved protocols requires fewer exchanged messages and provided more secure protection for the client’s identity. In this paper, we propose two protocols require less exchanged messages than Juang’s protocols. In addition to this advantage, we point out that the identity protection of Juang’s protocol is computationally inefficient for the server and efficient identity protection is proposed in the second proposed protocol.