Yunsik Kwak

Real Time Traceability and Monitoring System for Agricultural Products Based on Wireless Sensor Network

A system to monitor and trace the yields and distribution of agricultural products is an important precision agricultural application. The system can be used to predict the next years yields or provide the distribution channel of agricultural products from farmers to customers. Existing traceability and monitoring systems, usually, are implemented by using both wireless sensor network (WSN) and radio frequency identification (RFID) techniques. In this paper, we propose a system architecture that only requires WSN techniques and implement it. The implementing system consists of sensor nodes, communication hubs, a communication protocol, and an event detection engine. We define events to trace and monitor agricultural products, and our event detection engine detects those events by using the current location and the status of each sensor node. We describe the overall architecture of the proposed system and implementation details.

Skyline query processing in sensor network based on data centric storage.

Data centric storages for sensor networks have been proposed to efficiently process multi-dimensional range queries as well as exact matches. Usually, a sensor network does not process only one type of the query, but processes various types of queries such as range queries, exact matches and skyline queries. Therefore, a sensor network based on a data centric storage for range queries and exact matches should process skyline queries efficiently. However, existing algorithms for skyline queries have not considered the features of data centric storages. Some of the data centric storages store similar data in sensor nodes that are placed on geographically similar locations. Consequently, all data are ordered in a sensor network. In this paper, we propose a new skyline query processing algorithm that exploits the above features of data centric storages.

Design of Cold Chain Application Framework (CCAF) Based on IOT and Cloud

In this paper, we propose a smart cold chain application framework (SCCAF) based on Cloud and IOT (Internet of Things) techniques. The purpose of SCCAF is to provide PaaS (Platform as a Service) and IaaS (Infra as a Service) to users who want to develop and apply cold chain management systems with low cost and in short time. Also, SCCAF enables users to use any type of IOT devices such as RFID tags, WSN sensor nodes, BLE (Bluetooth Low Energy) sensor nodes and so on. We define common components by generalizing function of existing cold chain management systems, and design SCCAF based on Hadoop and Spark to store the large amount of data stream on salable storage and process stream data to detect events and assess risks in cold chain.

Software RAID for Data Intensive Applications in Cloud Computing

In this paper, we propose a software RAID to support data intensive applications in cloud computing. The proposed software RAID is based on DDR-SSD to enhance the performance of existing RAID systems. Also, we take the characteristics of DDR-SSD into account to design our software RAID. RAID level 5 which is generally used in data intensive applications has small write problems. In RAID level 5, to process a small write request, we need to read its parity block stored in disk, read old block, perform XOR operation, and write updated block and parity block. In this paper, we propose a differential-logging method which carefully considers the DDR-SSD to solve the small write problem in RAID level 5. We show that our proposed method out performs the existing software RAID through simulations.

Software RAID 5 for OLTP Applications with Frequent Small Writes

In this paper, we propose a DDR-SSD conscious software RAID system for OLTP applications. The proposed software RAID employs a logging based method to improve the performance of software RAID 5. Small writes that are frequently occurred in OLTP applications are the main factor to degrade the performance of RAID systems. Several methods for a hard disk based software RAID system are proposed to solve the small write problems. It is straightforward to apply the existing methods to a DDR-SSD based software RAID system. However, DDR-SSDs have unique characteristics which are different from hard disks. If the unique characteristics are taken into account carefully when designing the software RAID system, its overall performance will be improved. In this paper, we propose a differential-logging method considering the DDR-SSD to solve the small write problem. We show that our proposed method outperforms the existing software RAID through simulations.

Configurations of Dual RAID System

The RAID system is used to get the high performance and reliability of disk system. The many RAID system concerned the disk failure, and have the recover policy. But the probability of the RAID system failure is not lower than that of the disk failure. To implement the robust RAID system, the redundancy of RAID controller is also needed. In this paper, we provide three configurations of Dual RAID system. And we consider the characteristics of each Dual RAID system.

Performance Analysis of RAID Implementations

There are many RAID configurations and two types of RAID implementations. To decide which configuration or implementation is suitable to an application, the performance information of RAID system are required. In this paper, we evaluate the performance of RAID system. For evaluating the performance, we use many parameters composed of two RAID configurations, two implementations, and two types of storage devices. Two configurations, which we use, are level 0 and 5. Two implementations are hardware and software RAID. As a result, if we want to construct the RAID level 0, it is good decision to use the software RAID. And the overhead of the software RAID level 5 is higher than that of hardware RAID.

Positioning using Acceleration and Moving Direction

The position of user or object is important context to provide the user with the user-oriented services. To position the user or object, we propose the autonomous positioning technique in this paper. In the autonomous positioning technique, the acceleration and the moving direction are used to position the user or the moving object. The moving length is calculated from the acceleration. And the calculated moving length and the direction is used to calculate new position of user or object. To show that the autonomous positioning technique is effective and useful, we implement the positioning device which uses the autonomous positioning technique. From the prototype implemented, we know that the proposed positioning is useful.