• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.3
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• pp.407-416
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• 2021

An active phased array antennas can not only electrically steer the beam by controlling the weighting of the excitation signal, but can also form a pattern null in the direction of the interference source. The weight of the excitation signal to steer the main beam can be easily calculated based on the position of the radiating element. In addition, the weight of the excited signal for pattern null formation can also be calculated by setting the required radiation pattern and using WLSM(Weighted Least Squares Method). However, in a general wireless communication network environment, the location of the interference source is unknown. Therefore, an adaptive pattern null synthesis is needed. In this paper, it was confirmed that pattern null synthesis according to the required radiation characteristic was possible. And based on this, adaptive pattern null synthesis into the direction of an interference source was studied using a binary search algorithm based on observation area. As a result of conducting a simulation based on the presented technique, it was confirmed that adaptive pattern null forming into the direction of an interference is possible in efficient way.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.5
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• pp.628-636
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• 2021

This paper contains the implementation and performance evaluation results of a system that collects environmental data at the time when the wild animal intrusion occurred at farms and then predicts future wild animal intrusions through a machine learning-based Vector Autoregression(VAR) model. To collect the data for intrusion prediction, an IoT-based hardware prototype was developed, which was installed on a small farm located near the school and simulated over a long period to generate intrusion events. The intrusion prediction service based on the implemented VAR model provides the date and time when intrusion is likely to occur over the next 30 days. In addition, the proposed system includes the function of providing real-time notifications to the farmers mobile device when wild animals intrusion occurs in the farm, and performance evaluation was conducted to confirm that the average response time was 7.89 seconds.

• Journal of the Korea Society of Computer and Information
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• v.26 no.2
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• pp.125-132
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• 2021

In this paper, We propose a study on the construction of an environment for collaboration in mixed reality and a method for working with wearable IoT devices. Mixed reality is a mixed form of virtual reality and augmented reality. We can view objects in the real and virtual world at the same time. And unlike VR, MR HMD does not occur the motion sickness. It is using a wireless and attracting attention as a technology to be applied in industrial fields. Myo wearable device is a device that enables arm rotation tracking and hand gesture recognition by using a triaxial sensor, an EMG sensor, and an acceleration sensor. Although various studies related to MR are being progressed, discussions on developing an environment in which multiple people can participate in mixed reality and manipulating virtual objects with their own hands are insufficient. In this paper, We propose a method of constructing an environment where collaboration is possible and an interaction method for smooth interaction in order to apply mixed reality in real industrial fields. As a result, two people could participate in the mixed reality environment at the same time to share a unified object for the object, and created an environment where each person could interact with the Myo wearable interface equipment.

• Smart Media Journal
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• v.9 no.4
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• pp.60-65
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• 2020

The monopulse tracking algorithm can estimate the location of a partner station based on an RF (Radio Frequency) signal. The location of the partner station is estimated based on the monopulse ratio curve (MR-C), which is calculated based on the sum and difference signal patterns of an antenna. Therefore, the range in which the estimated location can be calculated with high accuracy increases in proportion to the linear region of MR-C. In this paper, we proposed a method to extend the linear region of the MR-C curve using the beamforming technique for the tracking antenna system using the active phased array antenna. Simulation results based on the same antenna system, it was confirmed that the linear region of MR-C was enlarged by about twice as much as the general case where the proposed method was not applied.

• Journal of the Korea Society of Computer and Information
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• v.26 no.1
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• pp.103-110
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• 2021

In this paper, we compare two access control mechanisms for D2D(Device-to-Device) systems in 5G wireless networks and propose an effective access control for 5G D2D networks. Currently, there is no specified access control for 5G D2D networks but there can be two access control approaches for 5G D2D networks. One is the UE-to-Network Relay based access control and the other is the Remote UE(User Equipment) based access control. The former is a UE-to-Network Relay carries out the access control check for 5G D2D networks but the latter is a Remote UE performs the access control check for 5G D2D networks. Through simulation and evaluation, we finally propose the Remote UE based access control for D2D systems in 5G wireless networks. The proposed approach minimizes signalling overhead between the UE-to-Network Relay and the Remote UE and more efficiently performs the access control check, when the access control functionalities are different from the UE-to-Network Relay in 5G D2D networks.

• Journal of the Korea Convergence Society
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• v.13 no.3
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• pp.227-237
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• 2022

With the growing interest in convergence, there have been various attempts to measure convergence, but the definition of convergence is ambiguous and consensus on appropriate indicators has not been reached, so measurement of convergence is still at a rudimentary stage. In this study, using the KSIC-IPC linkage table developed by the Korean Intellectual Property Office to analyze the correlation and impact of patents, industry, economy, and population, we propose a new evaluation model that can evaluate industry convergence from patent data. In addition, it was verified whether the industry convergence derived from this properly reflects the corporate convergence characteristics. As a result of classifying the convergence of 39,740 patents owned by global major automobile companies, and evaluating the degree of convergence of each company, it was confirmed that the industry convergence derived using the KSIC-IPC linkage table better reflects the corporate convergence characteristics than the technology convergence classified by IPC co-classification. Therefore, the industry convergence data of automotive sector derived from the new industry convergence evaluation model using the KSIC-IPC linkage table is expected to be widely used for future convergence research.

• Journal of the Korea Society of Computer and Information
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• v.27 no.7
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• pp.83-92
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• 2022

In this paper, we designed an algorithm that can control the state of PM by learning the chain failure pattern of PHM based air conditioning facility. It is an inevitable spread of PM due to the downtime caused by the failure of the air conditioning facility. The algorithm developed by us is to establish a PM management system through PHM, and it is an algorithm that maintains a constant stabilization state through learning the stop/operation pattern of the air conditioner and manages PM based on this. As a result of the simulating at a subway station for the performance qualification of the algorithm, it was verified that the concentration of PM reduces by 30% on average. In the case of stations with many passengers using the subway, the concentration of PM exceeded the Ministry of Environment Standards(100 ㎍/m³), but it was verified that the concentration of PM was improved at all stations where the simulation was conducted. In the future research is to expand the system to comprehensively manage not only PM but also pollutants such as CO₂, CO, and NO₂ in subway stations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.5
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• pp.793-801
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• 2022

Most Bluetooth devices are commonly used in various ways these days, but they can be often lost due to small-size devices. However, most Bluetooth protocol do not provide authentication functions to legitimate owners, and thus someone who obtains the lost Bluetooth device can easily connect to their smart devices to use it. In this paper, we propose NBAS can authenticates legitimate owners using NFT on lossy Bluetooth devices.NBAS generates a digital wallet on the blockchain using the decentralized network Ethereum blockchain and facilitating the MAC address of the Bluetooth device in the digital wallet. The owner of the wallet uses a private key to certify the Bluetooth device using NFT. The initial pairing time of NBAS was 10.25 sec, but the reconnection time was 0.007 sec similar to the conventional method, and the pairing rejection time for unapproved users was 1.58 sec on average. Therefore, the proposed NBAS effectively shows the device authentication over the conventional Bluetooth.

• Journal of Industrial Convergence
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• v.20 no.10
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• pp.17-24
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• 2022

Lora, a non-band network technology of the long-distance wireless standard LPWAN standard, uses ABP and OTTA methods and AES-128-based encryption algorithm (shared key) for internal terminal authentication and integrity verification. Lora's recent firmware tampering vulnerability and shared-key encryption algorithm structure make it difficult to defend against MITM attacks. In this study, the consensus algorithm(PBFT) is applied to the Lora network to enhance safety. It performs authentication and PBFT block chain creation by searching for node groups using the GPS module. As a result of the performance analysis, we established a new Lora trust network and proved that the latency of the consensus algorithm was improved. This study is a 4th industry convergence study and is intended to help improve the security technology of Lora devices in the future.

• Journal of Internet of Things and Convergence
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• v.8 no.3
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• pp.47-54
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• 2022

The purpose of this study was to examine the mediating effect of family organization patterns of family resilience on the relationship between parenting stress and parenting efficacy. A total of 263 participants who have children with disabilities participated in this study by responding to the following questionnaires: Parenting Stress Index(PSI), Family Resilience Scale, Parenting Efficacy Scale. The collected data were analyzed using SPSS 25.0 and Amos 22.0. The main findings were as follows. There was a significant partial mediating effect of family organization patterns of family resilience on the relationship between parenting stress and parenting efficacy. The results of this study can provide useful information for family who have children with disabilities. suggestions for future study were discussed.