• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.9
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• pp.3250-3265
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• 2014

Integrated WiMAX and WiFi networks is of great potential for the future due to the wider coverage of WiMAX and the high data transport capacity of WiFi. However, seamless and secure handover (HO) is one of the most challenging issues in this field. In this paper, we present a novel vertical HO authentication scheme with privacy preserving for WiMAX-WiFi heterogeneous networks. Our scheme uses ticket-based and pseudonym-based cryptographic methods to secure HO process and to achieve high efficiency. The formal verification by the AVISPA tool shows that the proposed scheme is secure against various malicious attacks and the simulation result indicates that it outperforms the existing schemes in terms of communication and computation cost.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.134-141
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• 2023

As robotic technology expands into various fields, robots need to execute some complicated tasks in diverse environments. However, the previous robotic software solutions were limited to independent systems. We can not adapt to diverse functionalities and environments. This makes it hard to provide rapid and effective services and leads to costs and losses in the development process. To overcome these problems, we propose a robot software framework with behavior trees based on ROS2. This framework simplifies complex robot behaviors through behavior trees and makes it easy to modify, extend, and reuse robot behaviors. Furthermore, ROS2 standardizes connections between software modules, enhances the robot's flexibility, and enables independent development and testing of software. Our framework aims to provide a foundation for high-quality robot service provision by supporting the modularity, reusability, independent development, and testing required by intelligent robots that need to provide services in various environments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.1043-1063
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• 2019

With delegating proxy to process data before outsourcing, data owners in restricted access could enjoy flexible and powerful cloud storage service for productivity, but still confront with data integrity breach. Identity-based data auditing as a critical technology, could address this security concern efficiently and eliminate complicated owners' public key certificates management issue. Recently, Yu et al. proposed an Identity-Based Public Auditing for Dynamic Outsourced Data with Proxy Processing (https://doi.org/10.3837/tiis.2017.10.019). It aims to offer identity-based, privacy-preserving and batch auditing for multiple owners' data on different clouds, while allowing proxy processing. In this article, we first demonstrate this scheme is insecure in the sense that malicious cloud could pass integrity auditing without original data. Additionally, clouds and owners are able to recover proxy's private key and thus impersonate it to forge tags for any data. Secondly, we propose an improved scheme with provable security in the random oracle model, to achieve desirable secure identity based privacy-preserving batch public auditing with proxy processing. Thirdly, based on theoretical analysis and performance simulation, our scheme shows better efficiency over existing identity-based auditing scheme with proxy processing on single owner and single cloud effort, which will benefit secure big data storage if extrapolating in real application.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.10
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• pp.3989-4006
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• 2020

The intelligent agriculture monitoring is based on the perception and analysis of environmental data, which enables the monitoring of the production environment and the control of environmental regulation equipment. As the scale of the application continues to expand, a large amount of data will be generated from the perception layer and uploaded to the cloud service, which will bring challenges of insufficient bandwidth and processing capacity. A fog-based offline and real-time hybrid data analysis architecture was proposed in this paper, which combines offline and real-time analysis to enable real-time data processing on resource-constrained IoT devices. Furthermore, we propose a data process-ing algorithm based on the incremental principal component analysis, which can achieve data dimensionality reduction and update of principal components. We also introduce the concept of Squared Prediction Error (SPE) value and realize the abnormal detection of data through the combination of SPE value and data fusion algorithm. To ensure the accuracy and effectiveness of the algorithm, we design a regular-SPE hybrid model update strategy, which enables the principal component to be updated on demand when data anomalies are found. In addition, this strategy can significantly reduce resource consumption growth due to the data analysis architectures. Practical datasets-based simulations have confirmed that the proposed algorithm can perform data fusion and exception processing in real-time on resource-constrained devices; Our model update strategy can reduce the overall system resource consumption while ensuring the accuracy of the algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1388-1393
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• 2007

The Microprocessor Based Laboratory Systems(MBL) with the remote access functional could put basic science experimental facilities together by providing a modem platform that the students can utilize simultaneously to learn basic physics, chemistry and biology, Our educator target platform combines a highly integrated 8-bit embedded Atmega128 processor and real time embedded OS (operating system), allowing plenty of headroom for follow-on basic science projects for students. The proposed MBL-NUTOS (Microprocessor Based Laboratory-NUT/OS) employed in the lab are available with internet base simulation capabilities, on public servers and students personal PCs, enabling the students to study at home and increasing the opportunity of accessing for the science laboratory facility.

• International journal of advanced smart convergence
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• v.9 no.4
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• pp.149-155
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• 2020

In the software industry of Korean Small and Medium-sized Enterprise(SME)s, the development process is often not mature. This may lead to failures in quality control and output management. As a result, the quality of the software can be degraded. To solve the problem, the software visualization technique, which is from the National IT Industry Promotion Agency Software Engineering Center can be applied. We have experienced with mentoring not only the visualization of software development process, but also various visualization process of SMEs. However, the existing software visualization method was difficult to install environment and its time cost was high. This paper proposes a software visualization environment through a cloud service along with a case of building a software visualization environment. We expect that this method will make it easier to build a visualization environment and improve the quality of SME software.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.11
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• pp.4268-4290
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• 2015

Future mobile communications face enormous challenges as traditional voice services are replaced with increasing mobile multimedia and data services. To address the vast data traffic volume and the requirement of user Quality of Experience (QoE) in the next generation mobile networks, it is imperative to develop efficient content distribution technique, aiming at significantly reducing redundant data transmissions and improving content delivery performance. On the other hand, in recent years cloud computing as a promising new content-centric paradigm is exploited to fulfil the multimedia requirements by provisioning data and computing resources on demand. In this paper, we propose a cooperative caching framework which implements State based Content Distribution (SCD) algorithm for future mobile networks. In our proposed framework, cloud service providers deploy a plurality of cloudlets in the network forming a Distributed Cloud Service Network (DCSN), and pre-allocate content services in local cloudlets to avoid redundant content transmissions. We use content popularity and content state which is determined by content requests, editorial updates and new arrivals to formulate a content distribution optimization model. Data contents are deployed in local cloudlets according to the optimal solution to achieve the lowest average content delivery latency. We use simulation experiments to validate the effectiveness of our proposed framework. Numerical results show that the proposed framework can significantly improve content cache hit rate, reduce content delivery latency and outbound traffic volume in comparison with known existing caching strategies.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.12
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• pp.5785-5804
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• 2019

The information of localization is a fundamental requirement in wireless sensor network (WSN). The method of distance vector-hop (DV-Hop), a range-free localization algorithm, can locate the ordinary nodes by utilizing the connectivity and multi-hop transmission. However, the error of the estimated distance between the beacon nodes and ordinary nodes is too large. In order to enhance the positioning precision of DV-Hop, fast triangle flip bat algorithm, which is based on curve strategy and rank transformation (FTBA-TCR) is proposed. The rank is introduced to directly select individuals in the population of each generation, which arranges all individuals according to their merits and a threshold is set to get the better solution. To test the algorithm performance, the CEC2013 test suite is used to check out the algorithm's performance. Meanwhile, there are four other algorithms are compared with the proposed algorithm. The results show that our algorithm is greater than other algorithms. And this algorithm is used to enhance the performance of DV-Hop algorithm. The results show that the proposed algorithm receives the lower average localization error and the best performance by comparing with the other algorithms.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.17-23
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• 2019

IaaS is well known as a very cost effective computing service which enables required infrastructures to be rented on demand without ownership of real hardwares. It is very suitable for price sensitive services due to pay-per-use style. Operators of such services would want to adjust utilization policy quickly by estimating costs for cloud infrastructures as soon as possible. However, swift response is not possible due to that cloud service providers provide a dozen or so hours delayed billing information. Our work proposes a realtime IaaS cost estimation model based on usages monitored by virtual machine instance. We operate PC laboratory service on a public cloud during full semester to validate our suggested model. From that experiment, an averaged disparity between estimation and actual cost is less than 5.2%.

• Journal of Internet Computing and Services
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• v.17 no.3
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• pp.33-43
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• 2016

In this study, 3D-image based course material has been suggested as a potential pedagogical tool for laboratory courses for aviational maintenance in vocational high schools. With a special focus on assembly/disassembly of the combustion chamber, 3D contents described here are created by Soildworks 2014 based on the textbook widely used in aviational high schools. By analyzing several textbooks currently adopted at various schools, we have clearly shown that the current text-based teaching method is far from being effective regarding providing adequate learning environment for high school students who study aviational maintenance. From the analysis of the conventional textbooks, it is seen that it is urgent that we should come up with more effective and efficient way of teaching methods for these topics at vocational high schools. Using Solidworks, we have developed very vivid 3D image-based course material for topics related to a combustion chamber in the airplane. Newly developed 3D material is seen to clearly show step by step procedures of assembly and disassembly of the combustion chamber which has crucial importance in the aviational laboratory courses. Especially the transparent feature in Solidworks could make it possible to observe the parts covered by outer casing, which can not be seen even in any laboratory class with real objects. 3D animated views could provided unprecedented learning environment for students to acquire core knowledge with ease for the maintenance of a combustion chamber. In order to provide easy access for students to this 3D-based course material, the exclusive viewer is also developed using MS office powerpoint 2007. An example of a learning plan using 3d course material is suggested as well.