• Journal of the Korea Convergence Society
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• v.9 no.6
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• pp.61-68
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• 2018

This paper propose the remote monitoring system using LoRa networks about storm overflow chamber, which is a device designed to discharge rainwater directly to a sewage treatment plant when it reaches a certain amount of rainfall during precipitation. In this system, when the information produced by the sensor is transmitted to the LoRa network server and updated, the application server can automatically receive data through the implemented communication interface. The application server carries out management functions of storm overflow chamber devices and subscription information, collects measured flow rate and opening-closing information, and provides statistical information using the collected data. The android app performs a firebase-based notification function to prompt the user of malfunctioning of the storm overflow chamber device.

• Journal of Digital Contents Society
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• v.19 no.9
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• pp.1779-1785
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• 2018

In this paper, we propose an error correction method to improve the accuracy of human activity recognition using sensor event data obtained by smart devices such as wearable and smartphone. In the context awareness through the smart device, errors inevitably occur in sensing the necessary context information due to the characteristics of the device, which degrades the prediction performance. In order to solve this problem, we apply Kalman filter's error correction algorithm to compensate the signal values obtained from 3-axis acceleration sensor of smart device. As a result, it was possible to effectively eliminate the error generated in the process of the data which is detected and reported by the 3-axis acceleration sensor constituting the time series data through the Kalman filter. It is expected that this research will improve the performance of the real-time context-aware system to be developed in the future.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.1
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• pp.47-55
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• 2016

As one of recent issues in the information and communication industry, internet of things has attracted attention to provide intelligent infrastructure services which connect and share data and information between real and virtual world. According to the development of these internet of things technologies, types of machines, telecommunication devices, and terminals are increasing tremendously. In this situation, connectivity and interoperability between internet of things components are important issues to build a hyper connected society. To visualize this society, it is important to set up and develop information and communication technology (ICT) standards among stakeholders. However, under limited budget and human resources, it is essential to rank standardization work items for setting standards with respect to efficiency. The purpose of this study is to provide a method for setting standardization strategies within group decision making. As a multi-criteria group decision making tool, analytic hierarchy process (AHP) is adopted and applied to determine the priorities of setting work items. The proposed method first defines decision making problem with objective, criteria, and alternatives which produces a hierarchy consisting of upper and lower criteria. Then, pairwise comparisons of academy and public sector experts are performed with respect to their relative meaning and importance. Individual surveys of expert groups are collected and summarized to determine relative criteria importance measures. Furthermore, to deliver reliable importance criteria measures, differences between academy and public sector expert groups are compared and tested using Mann-Whitney non-parametric test. The results are illustrated for useful guidelines to practical group decision making in standardization strategy establishments.

• Journal of Advanced Navigation Technology
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• v.19 no.1
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• pp.66-73
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• 2015

In this paper, an architecture of a perpetual smart video device and its energy control model for the internet of things (IoT) are proposed. The smart video device consists of a processor, an image sensor, a video codec, and a network controller. In the proposed energy control model, energy consumed by image sensing, video encoding, and transmission and energy harvested by solar panels are defined as an input and an output of a battery, an energy buffer. Frame rate, quantization parameter, and operating frequency of processor are defined as the energy control parameters, and these parameters control the input and the output energy of the energy buffer, finally control the energy left in the battery. The proposed energy control model is validated by the energy consumption measurement of the smart phone based platform for various combinations of energy control parameters, and can be used for the design of perpetual smart video device.

• Journal of Internet of Things and Convergence
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• v.5 no.1
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• pp.35-39
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• 2019

With the rapid development of the information society, the use of digital devices has increased dramatically and the importance of technology for analyzing them has increased. Digital evidence is stored in many places such as Prefetch, Recent, Registry, and Event Log even if the user has deleted it. Therefore, there is a disadvantage that the forensic analyst can not grasp the files used by the user at the beginning. Therefore, in this paper, we propose a method that the RemoveList folder exists so that the user can grasp the information of the deleted file first, and the information about the deleted file is automatically saved by using AES in RemoveList. Through this, it can be expected that the analyst can alleviate the difficulty of initially grasping the user's PC.

• Journal of Practical Engineering Education
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• v.12 no.1
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• pp.23-29
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• 2020

Data generated by the development of ICT, the diversification of ICT devices and services and the expansion of social media are categorized as big data characterized by the amount, variety and speed of the data. The spread of the use of big data is expected to have the effects of identifying the status quo by analyzing data in all industries, predicting the future, and creating opportunities to apply it. However, while it is imperative for these things to be done, the nation still lacks professional training institutions or curricula. In this case study, we will investigate and compare the state of education for the training of big data personnel in Korea, find out what level and level of education is being trained to nurture balanced professionals, and prepare an opportunity to think about how it can help students create value at a time when the need for education is growing in the wake of awareness of big data.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.2
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• pp.92-98
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• 2017

Data clustering determines a group of patterns using similarity measure in a dataset and is one of the most important and difficult technique in data mining. Clustering can be formally considered as a particular kind of NP-hard grouping problem. K-means algorithm which is popular and efficient, is sensitive for initialization and has the possibility to be stuck in local optimum because of hill climbing clustering method. This method is also not computationally feasible in practice, especially for large datasets and large number of clusters. Therefore, we need a robust and efficient clustering algorithm to find the global optimum (not local optimum) especially when much data is collected from many IoT (Internet of Things) devices in these days. The objective of this paper is to propose new Hybrid Simulated Annealing (HSA) which is combined simulated annealing with K-means for non-hierarchical clustering of big data. Simulated annealing (SA) is useful for diversified search in large search space and K-means is useful for converged search in predetermined search space. Our proposed method can balance the intensification and diversification to find the global optimal solution in big data clustering. The performance of HSA is validated using Iris, Wine, Glass, and Vowel UCI machine learning repository datasets comparing to previous studies by experiment and analysis. Our proposed KSAK (K-means+SA+K-means) and SAK (SA+K-means) are better than KSA(K-means+SA), SA, and K-means in our simulations. Our method has significantly improved accuracy and efficiency to find the global optimal data clustering solution for complex, real time, and costly data mining process.

• Journal of Digital Contents Society
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• v.19 no.5
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• pp.963-969
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• 2018

Wi-Fi and Bluetooth technologies are perhaps the most prominent examples of wireless communication technologies used in the Internet of Things (IoT) environment. Compared to widely used Wi-Fi, Bluetooth technology has some flaws including 1:1 connection (one-way) between Master and Slave, slow transmission, and limited connection range; Bluetooth is mainly used for connecting audio devices. Since the release of Bluetooth Low Energy (BLE), some of the flaws of Bluetooth technology have been improved but it still failed to become a competitive alternative of Wi-Fi. This paper presents a method of data transmission through broadcasting in BLE and demonstrates its performance, one-to-many data transfer result. The Connection-Free Data Transmission proposed in this paper will hopefully be utilized in special circumstances requiring 1:N data transmission or disaster security network.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.4
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• pp.739-746
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• 2020

The fourth industrial revolution introduced at world economic forum in 2016 has had huge effects on tourism industries as well as the change of core technologies in ICT such as big data, IoT, etc, This paper proposes the methods to propel tourism of Yoesu city through big data analysis and questionnaires. Sensitive words and positive-negative trend are extracted by Social Metrics and the keywords for Yeosu tour trends are extracted and analyzed by Naver datalab, and the results are visualized by R language. And frequency, difference, factor, covariance and regression analysis in SPSS are executed for the questionnaires for 493 visitors who traveled in Yeosu city. Sentiment analysis for Yeosu tour and maritime cable car shows that positive effect is much more than negative one. The analyses for questionnaires in SPSS show that Yeosu area is statistically significant to tour satisfaction index and tour revitalization for Yeosu, and favorite sightseeing places and searching electronic devices for age groups are different. The sightseeing places such as a maritime park with soft contents that give joyfulness and healing to tourists are highly attracted in both the big data and questionnaires analysis.

• Journal of Internet of Things and Convergence
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• v.1 no.1
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• pp.39-44
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• 2015

Organization is increasing the authorizing process to use public certificate and bio information. Certificate, has evolved to be able to parallel distributes the bio authentication and portable bio-authentication device. Authentication using an individual's PC and smart devices continue to generalize, while convenience for authentication is increased by comparison Study on cooperation with the security at the network level's a weak situation. If ask authentication method through the cooperation of the public certificate and bio information work with current network access control, there is a possibility to develop a more powerful security policy. by cooperation weaknesses against vulnerable personal authentication techniques on security token in a reliable and secure personal authentication techniques, such as bio-recognition, Bio Information for identification and to prevent exposing a methodology suggest to validate whether or not to carry out in this paper. In addition, organize the scenario that can work with the 802.1x network authentication method, and presented a proposal aimed at realization.