Hyunjun Jung

Durability Prediction for Concrete Structures Exposed to Chloride Attack Using a Bayesian Approach

Dept. of Civil & Environmental and Architectural Engineering, Korea University, Seoul 136-713, KoreaABSTRACT This paper provides a new approach for predicting the corrosion resistivity of reinforced concrete structuresexposed to chloride attack. In this method, the prediction can be updated successively by a Bayesian theory when additional dataare available. The stochastic properties of model parameters are explicitly taken into account into the model. To simplify the pro-cedure of the model, the probability of the durability limit is determined from the samples obtained from the Latin hypercube sam-pling technique. The new method may be very useful in designing important concrete structures and help to predict the remainingservice life of existing concrete structures which have been monitored.Keywords : corrosion, bayesian theory, durability prediction, remaining service life, monitoring.

A Network Coverage Information-Based Sensor Registry System for IoT Environments

The Internet of Things (IoT) is expected to provide better services through the interaction of physical objects via the Internet. However, its limitations cause an interoperability problem when the sensed data are exchanged between the sensor nodes in wireless sensor networks (WSNs), which constitute the core infrastructure of the IoT. To address this problem, a Sensor Registry System (SRS) is used. By using a SRS, the information of the heterogeneous sensed data remains pure. If users move along a road, their mobile devices predict their next positions and obtain the sensed data for that position from the SRS. If the WSNs in the location in which the users move are unstable, the sensed data will be lost. Consider a situation where the user passes through dangerous areas. If the user’s mobile device cannot receive information, they cannot be warned about the dangerous situation. To avoid this, two novel SRSs that use network coverage information have been proposed: one uses OpenSignal and the other uses the probabilistic distribution of the users accessing SRS. The empirical study showed that the proposed method can seamlessly provide services related to sensing data under any abnormal circumstance.

Development of a Successive LCC Model for Marine RC Structures Exposed to Chloride Attack on the Basis of Bayesian Approach

Dept. of Civil & Environmental and Architectural Engineering, Korea University, Seoul 136-713, KoreaABSTRACT A new life-cycle cost (LCC) evaluation scheme for marine reinforced concrete structures is proposed. In thismethod, unlike the conventional life-cycle cost evaluation performed during the design process, the life-cycle cost is updated suc-cessively whenever new information of the chloride penetration is available. This updating is performed based on the Bayesianapproach. For important structures, information required for this new method can be obtained without any difficulties because itis a common element of various types of monitoring systems. Using the new method, the life-cycle maintenance cost of structurescan be estimated with a good precision.Keywords : LCC, chloride penetration, bayesian approach, monitoring

Development of Sensor Registry System-Based Predictive Information Service Using a Grid

A sensor registry system (SRS) registers sensor metadata and provides them for a seamless semantic process. Recently, network coverage information-based SRS (NC-SRS) was developed to provide sensor information filtering by combining path prediction and network coverage checks. However, the NC-SRS has problems caused by issues such as termination of OpenSignal service and pre-building road segments. Therefore, this paper proposes a sensor registry system-based predictive information service (SRS-PIS) using a grid. SRS-PIS predicts a path based on the grid, checks the network coverage, and filters the sensor. This paper presents a grid-based real-time path prediction algorithm and an algorithm for grouping network service-disabled areas. To obtain network coverage information, we constructed and implemented a grid-based coverage map through experiment to measure the signal strength. As an evaluation, we compared features among SRS-based systems and SRS-PIS, and compared advantages and disadvantages between segment-based and grid-based methods.

A Reconfiguration Method for Preserving Network Bandwidth and Nodes Energy of Wireless Sensor Networks

In Wireless Sensor Networks (WSNs) and even in the Internet of Things (IoT) ecosystem, the reconfiguration of sensor variables is an important problem when the role of a system (or application) program’s sensor nodes needs to be adjusted in a particular situation. For example, the outdoor temperature in a volcanic zone, which is usually updated in a system every 10 s, should be updated every 1 s during an emergency situation. To solve this problem, this paper proposes a novel approach based on changing only a set of sensor variables in a part of a program, rather than modifying the entire program, in order to reduce both network congestion and the sensor nodes’ battery consumption. To validate our approach, we demonstrate an implementation of a proof-of-concept prototype system and also present results of comparative studies showing the performance and effectiveness of our proposed method.

Ontology Alignment by Using Discrete Cuckoo Search

ABSTRACT Ontology alignment is the way to share and reuse of ontology knowledge. Because of the ambiguity of concept, most ontology alignment systems combine a set of various measures and complete enumeration to provide the satisfactory result. However, calculating process becomes more complex and required time increases exponentially since the number of concept increases, more errors can appear at the same time. Lately the focus is on meta-matching using the heuristic algorithm. Existing meta-matching system tune extra parameter and it causes complex calculating, as a consequence, the results in the various data of specific domain are not good performed. In this paper, we propose a high performance algorithm by using DCS that can solve ontology alignment through simple process. It provides an efficient search strategy according to distribution of Levy Flight. In order to evaluate the approach, benchmark data from the OAEI 2012 is employed. Through the comparison of the quality of the alignments which uses DCS with state of the art ontology matching systems.Keywords:Ontology, Ontology Alignment, Cuckoo Search