Cheol-Su Son

Positioning System using Dynamic Location-convergence Adjustment Factor for Wireless LAN Infrastructures

Location positioning of an object is essential technology for Location-Based Services (LBS). Most location positioning systems use specially designed equipment. Because distribution of this specialized equipment is costly, many studies have been conducted on location positioning using only wireless equipment under a wireless LAN infrastructure. A cooperative location positioning system (CLPS) that uses the RSSI (Received Signal Strength Indicator) between mobile equipment, including mobile equipment and access points, requires great concentration in their applications to increase accuracy. This study investigates the relationship between nodes by analyzing a WiPS (Wireless LAN based indoor Positioning System), a similar type of CLPS, and proposes a improved cooperative positioning system to increase performance.

The Development of On-line Self-Test Module using Tracing Method

The higher thinking skills, such as creativity and problem-solving about a given problem, are difficult to assess and diagnose. For an accurate diagnosis of these higher thinking abilities, we need to fully observe learner`s problem-solving process or learner`s individual reports. However, in an online learning or virtual class environments, evaluation of learner`s problem-solving process becomes more difficult to diagnose. The best way to solve this problem is through reporting by tracking learner`s actions when he tries to solve a problem. In this study, we developed a module which can evaluate and diagnose student`s problem-solving ability by tracking actions in MS-Office suite, which is used by students to solve a given problem. This module performs based on the learner`s job history through user tracking. To evaluate the effectiveness of this diagnostic module, we conducted satisfaction survey from students who were preparing the actual MOS exams. As a result, eighty-one (81) of the participants were positive on the effectiveness of the learning system with the use of this module.

Scalable Cooperative Positioning System in Wireless Sensor Networks

Locations of positioned nodes as well as gathered data from nodes are very important because generally multiple nodes are deployed randomly and data are gathered in wireless sensor network. Since the nodes composing wireless sensor network are low cost and low performance devices, it is very difficult to add specially designed devices for positioning into the nodes. Therefore in wireless sensor network, technology positioning nodes precisely using low cost is very important and valuable. This research proposes Cooperative Positioning System, which raises accuracy of location positioning and also can find positions on multiple sensors within limited times. And this research verifies this technology is excellent in terms of performance, accuracy, and scalability through simulation.