Okkyung Choi

Personalized Mobile Information Retrieval System

Building a global Network Relations with the internet has made huge changes in personal information system and even comments left on a webpage of SNS(Social Network Services) are appreciated as important elements that would provide valuable information for someone. Social Network is a relation between individuals or groups, represented in a graph model, which converts the concept of psychological and social relations into a logical structure by using node and link. But, most of the current personalized systems on the basis of Social Network are built and constructed mainly in the PC environment, and the systems are neither designed nor implemented in mobile environment. Hence, the objective of this study is to propose methods of providing Personalized Mobile Information Retrieval System using NFC (Near Field Communication) Smartphone, which will be then used for Smartphone users. Besides, this study aims to verify its efficiency through a comparative analysis of existing studies.

Two-factor authentication system based on extended OTP mechanism

The recent increase in smartphone supply drives more users to utilize mobile financial services and it magnifies the importance of mobile security solutions. But it is not easy to defend cyber-attacks against financial services because the attacks get more diverse every year. The recent solution, OTP (one time password), is the most commonly used financial security measure to defend session attacks, but the downside is that it is hard to implement differentiated OTP creation mechanism to it. This research intends to solve the problem by suggesting Two-Factor authentication mechanism that utilizes graphical OTP. It is an extension of OTP mechanism which implements the graphical one time password to mobile financial security to reinforce mobiles way of authenticating with only ID and Password or digital certificate from banks; and it will defend against more diverse mobile hackings.

Extended OTP Mechanism Based on Graphical Password Method

OTP (One Time Password), a financial security authentication mechanism mainly used nowadays, is possible to cope with session attacks but has an weakness that it is difficult to apply differentiated mechanisms. This study intends to propose an extended OTP mechanism utilizing Graphical password method in order to solve such problem of the existing method. The proposed method is a Graphical password mechanism in story method based on user’s memory and can cope with various financial hackings and attack techniques. The existing authentication mechanisms have also a weakness in reliability to be used in mobile devices. In order to complement such weakness, GOTP (Graphical One Time Password) method was introduced so that users may use it in the Smartphone environment more easily and safely. Lastly, the effectiveness and validity were confirmed through an user study.

LZCode based compression method for effectively using the memory of embedded devices

SUMMARY Recently, with the rapid growth of embedded devices such as smart phones, tablet PC, and so on, the research on the effective use of flash memory widely used in embedded devices has been increasing. The growth is expected to continue more rapidly and the need for research will increase more. Therefore, there is a coming need for the effective use of main memory with flash memory in embedded devices. Essentially, all program codes have to be loaded into main memory before they can be executed. Then, the time for loading them into main memory is to be the sum of time for reading compression data from flash memory and for decompressing the data by a compressor residing in the main memory. Thus, the smaller the size of the compressor can make the utilization of main memory more effective. In this paper, we present our research on a lossless compression algorithm for reducing the size of the compressor while still maintaining compression rate and speed similar to LZCode suitable for embedded devices. Copyright

An interactive pervasive whiteboard based on MVC architecture for ubiquitous collaboration

Collaboration is about interactions among multiple users by sharing resources. With the advent of new generation of mobile access devices such as smartphone and tablet PC, we address this for ubiquitous collaboration—the capability of multiple users to link together with disparate access devices in anytime and in anywhere. The implementation and experiments of mobile applications for ubiquitous collaboration were challenge since cell phone (also referred to feature phone) prior to smartphone had high network latency and low computing performance. However, even though mobile device technologies and wireless networking are becoming more advanced with time, the research on the impact of ubiquitous collaboration is still immature. This paper extends our prior work with interactive multimedia services—whiteboard application on 3G and Wi-Fi Android platform based mobile devices, based on MVC (Model View Controller) architecture for ubiquitous collaboration. Then, we present interaction and usability study with multiple users using (wire, wireless) small-sized devices (smartphones), mid-sized devices (tablet PCs), and large-sized device (desktops) to show how disparate access devices and networking have an effect on software design of shared applications in ubiquitous collaboration system.

Design and Implementation of Data Access Control Mechanism based on OLAP

OLAP(On-Line Analytical Processing) is a tool to satisfy the requirements of managing overflowing data analysis. OLAP can provide an interactive analytical processing environment to every end-user. Security policy is necessary to secure sensitive data of organization according to users direct access database. But earlier studies only handled the subject in its functional aspects such as MDX(Multidimensional Expressions) and XMLA(XML for Analysis). This research work is purported for solving such problems by designing and implementing an efficient data access control mechanism for the information security on OLAP. Experimental evaluation result is proposed and its efficiency and accuracy are verified through it.

User Authentication Method using Vibration Cue on Smartphone

Mobile phone devices and memory card can be robbed and lost due to the carelessness that might be caused to leak personal information, and also company`s confidential information can be disclosed. Therefore, the importance of user authentication to protect personal information is increasing exponentially. However, there are the limitations that criminals could easily obtain and abuse information about individuals, because the input method of personal identification number or the input method of password might not be safe for Shoulder Surfing Attack(SSA). Although various biometric identification methods were suggested to obstruct the SSA, it is the fact that they also have some faults due to the inconvenience to use in mobile environments. In this study, more complemented service for the user authentication was proposed by applying Keystroke method in the mobile environments to make up for the faults of existing biometric identification method. Lastly, the effectiveness and validity of this study were confirmed through experimental evaluations.