Jungsook Kim

Maintaining consistency under isolation relaxation of web services transactions

For efficiently managing Web Services (WS) transactions which are executed across multiple loosely-coupled autonomous organizations, isolation is commonly relaxed. A Web services operation of a transaction releases locks on its resources once its jobs are completed without waiting for the completions of other operations. However, those early unlocked resources can be seen by other transactions, which can spoil data integrity and causes incorrect outcomes. Existing WS transaction standards do not consider this problem. In this paper, we propose a mechanism to ensure the consistent executions of isolation-relaxing WS transactions. The mechanism effectively detects inconsistent states of transactions with a notion of a completion dependency and recovers them to consistent states. We also propose a new Web services Transaction Dependency management Protocol (WTDP). WTDP helps organizations manage the WS transactions easily without data inconsistency. WTDP is designed to be compliant with a representative WS transaction standard, the Web Services Transactions specifications, for easy integration into existing WS transaction systems. We prototyped a WTDP-based WS transaction management system to validate our protocol.

A framework for ensuring consistency of Web Services Transactions

For efficiently managing Web Services (WS) transactions which are executed across multiple loosely-coupled autonomous organizations, isolation is commonly relaxed. A Web service operation of a transaction releases locks on its resources once its jobs are completed without waiting for the completions of other operations. However, those early unlocked resources can be seen by other transactions, which can spoil data integrity and cause incorrect outcomes. Existing WS transaction standards do not consider this problem. In this paper, we propose a mechanism to ensure the consistent executions of isolation-relaxing WS transactions. The mechanism effectively detects inconsistent states of transactions with a notion of an end-state dependency and recovers them to consistent states. We also propose a new Web services Transaction Dependency management Protocol (WTDP). WTDP helps organizations manage the WS transactions easily without data inconsistency. WTDP is designed to be compliant with a representative WS transaction standard, the Web Services Transactions specifications, for easy integration into existing WS transaction systems. We prototyped a WTDP-based WS transaction management system to validate our protocol.

RRMAC: A sensor network MAC for real time and reliable packet transmission

We designed RRMAC, a time division multiple access (TDMA) scheme guaranteeing hard real-time and reliable communication in a multi-hop convergecast network. We performed experiments to compare the performance of RRMAC and IEEE 802.15.4 and showed the advantages of RRMAC is WSN applications which require highly reliable real-time data transmission.

Vehicle speed measurement using wireless sensor nodes

Wireless sensor nodes capable of vehicle speed measurement can replace traditional speed measurement systems such as dual loop detectors. We designed a wireless sensor node for vehicle velocity measurement using two magnetic sensors. We present the sensor node architecture, velocity measurement methods, algorithms, and propose an implementation method for the SAD algorithm for which a hardware accelerator can be designed. We performed experiments to test how the velocity measurement accuracy depends on the sensor separation and algorithm used.

Intersection collision avoidance using Wireless sensor network

In this study, we propose intersection collision avoidance system in preventing traffic crashes at typical urban intersections. The proposed intersection crash prevention system would display the crash warning messages to the drivers when crash-prone conditions are detected through the sensor system installed along intersection approaches. It would further change the traffic signal setting in real-time, if necessary. To support the service, the intersection collision avoidance system introduces reliable MAC and accurate speed measurement mechanism.

Vehicular image based geographic information system for telematics environments - integrating map world into real world

In this paper, we design and implement an real image based geographic information system proposing a mechanism to deal with two worlds map and real in the same way in telematics environments. By using the designed geographic information system and by adapting the mechanism, we can make telematics services such as car navigation service and yellow page or white page service using geographic data more realistic.

Sensor Network for Traffic Safety

In this paper, we present a wireless sensor infrastructure for traffic safety. Real time information and possible dangerous situations are detected by wireless sensors installed in the roadway. The information is used to provide warning messages to drivers. We designed and implemented a flexible TDMA-CMSA/CA hybrid medium access control (MAC) protocol for wireless sensors guaranteeing deterministic packet transmission delay.

Safe driving system based on wireless sensor technology

The demand for the safety is increased in the telematics area. The main reason for the car accident is drivers delay in recognition about danger. About 45% car crash comes from delayed recognition. In order to solve the safety problem, we propose the wireless sensor system which can reduce the danger by warning invisible and unexpected risk in advance. In the consideration of environment which our system is deployed, our wireless sensor system for safety is composed of wireless sensor node sensing car existence with magnetic sensors, wireless sink node relaying the sensed data to the main server, and base station which is main server gathering all sensed data from sensor node and generating alarm messages. It is expected that our system successfully reduce car accident with wireless sensor network technology.

Algorithm and system for traffic safety on the intersection

The demand for the safety is increased in the telematics area. The main reason for the car accident is drivers delay in recognition and error in operation and judgment about danger. About 45 % car crash comes from delayed recognition and 28 % comes from error in operation and judgment. In order to solve the safety problem, we propose the wireless sensor system which can reduce the danger by warning invisible and unexpected risk in advance. In the consideration of environment which our system is deployed, our wireless sensor system for safety is composed of wireless sensor node sensing car existence with magnetic sensors, wireless relay node relaying the sensed data to the main server, and base station which is main server gathering all sensed data from sensor node and generating alarm messages. It is expected that our system successfully reduce car accident with wireless sensor network technology.

The next generation telematics service platform in ubiquitous environments

It is becoming desirable for users to easily and instantaneously use software anywhere and anytime. However, current telematics service platform, i.e. downloading, installing and configuring software, is not feasible for it. In this paper, we propose a new software streaming system called TeleASP. The TeleASP creates virtual applications from legacy application without modification. The virtual application can be deployed and executed on any devices on demand. Also, the TeleASP allows software to be streamed. The transmission of the software can be completely transparent to the user. Our streaming method can scientifically reduce the application load time since prefetching a service block, overlapping of transmission and execution of the virtual software, adopting a local cache into a terminal.