Test of Communication Distance Measurement of Fishing Gear Automatic System Based on Private LoRa
이성렬 Seong-real Lee , 김세훈 Se-hoon Kim
24(2) 61-66, 2020
이성렬 Seong-real Lee , 김세훈 Se-hoon Kim
DOI: JANT Vol.24(No.2) 61-66, 2020
Since the ocean accounts for 70.8 percent of the earth's surface, the success of IoT technology in the marine industry is to collect information from devices placed in a wider range. LPWA is a feature with a wide range of communication and is very suitable for deployment in the ocean. In this paper, the real-sea performance distance experiment was carried out based on Private LoRa, a key technology for executing the electronic phrase real-name system. A private LoRa module based on sx1276 was developed, and Gateway was developed to transfer data received by private LoRa to the server using SKT Cat. M1. After installing gateways at 599 meters above sea level and experimenting with data transmission and reception at 25 km, 40 km and 60 km, we were able to see that the communication success rate was obtained to be 96.1%. 97.1% and 96.2% respectively.
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Design and Implementation of IoT Terminal Equipment for Vessels using Thuraya Geo-stationary Orbit Satellite
장원창 Won-chang Jang , 이명의 Myung-eui Lee
24(2) 67-72, 2020
장원창 Won-chang Jang , 이명의 Myung-eui Lee
DOI: JANT Vol.24(No.2) 67-72, 2020
Satellite communication is not used by many people like mobile communication, but it is a necessary technology for public service and communication services, such as providing the Internet in military, disaster, remote education and medical services, island areas, and infrastructure vulnerable areas. However, on ships and aircraft, mobile communications requiring base stations are either unavailable or restricted in their use. In this paper, we used a Raspberry Pi board as the terminal device to communicate network through satellite modem and PPP protocol, and implemented two-way data link using the text message of the modem to connect to the Thuraya geo-stationary orbit network. In addition, I/O devices were connected to the controller of the terminal equipment to design and implement an IoT device system for ships that can remotely access the system under control and control I/Os and transmit measured data through various sensors.
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Flight Range and Time Analysis for Classification of eVTOL PAV
이봉술 Bong-sul Lee , 윤주열 Ju-yeol Yun , 황호연 Ho-yon Hwang
24(2) 73-84, 2020
이봉술 Bong-sul Lee , 윤주열 Ju-yeol Yun , 황호연 Ho-yon Hwang
DOI: JANT Vol.24(No.2) 73-84, 2020
To overcome ground congestions due to growing number of cars, a lot of companies have proposed personal aerial vehicle (PAV). Among PAV, electric vertical take-off and landing (eVTOL) aircrafts capable of vertical take-off and landing with electric power are drawing attention, and their configurations vary from multicopters to tilt ducted fans. This study tries to analyze the characteristics of each eVTOL design configurations. Parasite drag was calculated using component build up method for Vahana, Aurora, Volocopter representing each eVTOL PAV type of tilt-wing, compound, and multicopter. Wetted area and induced drag was calculated using OpenVSP and XFLR5 that are aircraft design and aerodynamic analysis software. The batteries used in the eVTOL PAV was assumed as Tesla 2170 batteries and flight ranges were calculated. Also, energy consumption and maximum flight time for the given mission profile including take-off and landing, cruising segments were compared for each eVTOL.
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Design of Low-complexity FFT Processor for Multi-mode Radar Signal Processing
박예림 Yerim Park , 정용철 Yongchul Jung , 정윤호 Yunho Jung
24(2) 85-91, 2020
박예림 Yerim Park , 정용철 Yongchul Jung , 정윤호 Yunho Jung
DOI: JANT Vol.24(No.2) 85-91, 2020
Recently, a multi-mode radar system was designed for efficient operation of unmanned aerial vehicles (UAVs) in various environments, which has the advantage of being able to integrate and utilize methods of the pulse Doppler (PD) radar and the frequency modulated continuous wave (FMCW) radar. For the range detection part of the multi-mode radar signal processor (RSP), the hardware structure using the FFT processor and the IFFT processor is required to be designed in a way that improves efficiency on the area side. In addition, given the radar application environment that requires a variety of distance resolutions, FFT processors need to support variable-length operations. In this paper, the FFT processor and IFFT processor in multi-mode RSP range estimation are designed and proposed as hardware for a single FFT processor that supports variable length operation of 16-1024 points. The proposed FFT processor designed in hardware description language (HDL) and can be implemented with 7,452 logic elements and 5,116 registers.
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Assisted SBAS Global Navigation Satellite System Operation Method for Reducing SBAS Time to First Fix
이주현 Ju Hyun Lee , 김일규 Il Kyu Kim , 서흥석 Hung Seok Seo
24(2) 92-100, 2020
이주현 Ju Hyun Lee , 김일규 Il Kyu Kim , 서흥석 Hung Seok Seo
DOI: JANT Vol.24(No.2) 92-100, 2020
Satellite-based argumentation systems (SBAS) is a system that enhances the accuracy, integrity, availability and continuity of GNSS navigation users by using geostationary orbit (GEO) satellites to send correction information and the failures of global navigation satellite system (GNSS) satellites in the form of messages. The correction information provided by SBAS is pseudorange error, satellite orbit error, clock error, and ionospheric delay error at 250 bps. Therefore, A lot of message processing are required for the SBAS navigation. There is a need to reduce SBAS time to first fix (TTFF) for using SBAS navigation in systems with short operating time. In this paper, A-SGNSS operation method was proposed for reducing SBAS TTFF. Also, A-SGNSS TTFF and availability were analyzed.
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A Characteristics of Control System for Induction Motor using a Speed Estimation Algorithm
황락훈 Lark-hoon Hwang , 나승권 Seung-kwon Na , 강진희 Jin-hee Kang
24(2) 101-107, 2020
황락훈 Lark-hoon Hwang , 나승권 Seung-kwon Na , 강진희 Jin-hee Kang
DOI: JANT Vol.24(No.2) 101-107, 2020
In order to smoothly control the speed of the induction motor, it is necessary to obtain the required rotor speed information. In order to obtain the speed information, it must be obtained using a sensor, but it can also be obtained using an appropriate algorithm without using a sensor. In order to obtain speed information, a system was designed using a model reference adaptive system (MARS). Indirect vector control, one of the speed control methods of induction motors, was calculated from the motor current and rotor parameter values. The method of obtaining the position information of the magnetic flux by combining the slip frequency with the rotor speed was used. It is possible to simply perform instantaneous current control in a wide speed range without actual magnetic flux information, and has the advantage that the structure of the controller is simple. Therefore, in this paper, the control system was constructed based on the indirect vector control method, and the speed control system of the induction motor was developed by estimating the required rotor speed information as an intelligent algorithm developed without using it as a sensor.
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Design of High Efficiency Switching Mode Class E Power Amplifier and Transmitter for 2.45 GHz ISM Band
고석현 Seok-hyeon Go , 구경헌 Kyung-heon Koo
24(2) 107-114, 2020
고석현 Seok-hyeon Go , 구경헌 Kyung-heon Koo
DOI: JANT Vol.24(No.2) 107-114, 2020
A power amplifier of 2.4 GHz ISM band is designed to implement a transmitter system. High efficiency amplifiers can be implemented as class E or class F amplifiers. This study has designed a 20 W high efficiency class E amplifier that has simple circuit structure in order to utilize for the ISM band application. The impedance matching circuit was designed by class E design theory and circuit simulation. The designed amplifier has the output power of 44.2 dBm and the power added efficiency of 69% at 2.45 GHz. In order to apply 30 dBm input power to the designed power amplifier, voltage controlled oscillator (VCO) and driving amplifier have been fabricated for the input feeding circuit. The measurement of the power amplifier shows 43.2 dBm output and 65% power added efficiency. This study can be applied to the design of power amplifiers for various wireless communication systems such as wireless power transfer, radio jamming device and high power transmitter.
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The Present Status and Future of Disaster Safety Communication Network
홍성화 Sung-hwa Hong , 이성렬 Seong-real Lee
24(2) 115-120, 2020
홍성화 Sung-hwa Hong , 이성렬 Seong-real Lee
DOI: JANT Vol.24(No.2) 115-120, 2020
PS-LTE, which is mentioned as a next-generation disaster network technology, is a communication technology that supports communication between terminals and group communication necessary for public safety communication based on LTE technology. Currently, Korea is establishing a PS-LTE network construction plan and installing a PS-LTE system. The world is currently making a lot of efforts to build a disaster network system using PS-LTE. However, due to the characteristics of the closed network that only the related persons can access, it can not be operated like the existing commercial network, so it is necessary to build a new network. And it is expected that many periods and costs will be required. In order to establish a disaster safety communication network efficiently, it is necessary to consider the linkage of PS-LTE network, which is newly constructed by complementing the problems such as security and access priority to existing LTE network rather than unconditional new construction.
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Improvement of Resource Utilization by Dynamic Spectrum Hole Grouping in Wideband Spectrum Cognitive Wireless Networks
이진이 Jin-yi Lee
24(2) 121-127, 2020
이진이 Jin-yi Lee
DOI: JANT Vol.24(No.2) 121-127, 2020
In this paper, we propose a dynamic spectrum hole grouping method that changes the grouping range of spectrum hole according to the resources amount required by secondary users in wideband spectrum cognitive wireless networks, and then the proposed method is applied to channel allocation for the secondary user service. The proposed method can improve waste of resources in the existing static spectrum hole grouping in virtue of grouping dynamically as much the predicted spectrum holes resources as secondary users require. Simulation results show that channel allocation method with the proposed dynamic grouping outperforms that with the static grouping method in resources utilization under acceptable secondary user service performance.
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One-dimensional Positioning using Iterative Linear Regression Based on Received Signal Strength and Mobility Information
이동준 Dong-jun Lee , 김다영 Da-yeong Kim , 이은혜 Eun-hye Lee
24(2) 128-133, 2020
이동준 Dong-jun Lee , 김다영 Da-yeong Kim , 이은혜 Eun-hye Lee
DOI: JANT Vol.24(No.2) 128-133, 2020
In this study, an 1-dimensional positioning method using iterative linear regression for path loss expression is proposed. In the proposed method, received signal strengths (RSS) measured in several locations and distances between the measuring locat ions obtained by dead reckoning are used to derive a linear regression for the path loss from the transmitting beacon. In the proposed method, for the distance between the transmitting beacon and a target measuring location, several tentative values are assumed. For each tentative value, a linear regression is obtained. Among the linear regression expressions, the one closest to the known reference RSS value is selected and used to derive the distance to the target location. Test results show that the proposed method is more accurate than path loss model.
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Telemetry System Encryption Technique using ARIA Encryption Algorithm
최석훈 Seok-hun Choi , 이남식 Nam-sik Lee , 김복기 Bok-ki Kim
24(2) 134-141, 2020
최석훈 Seok-hun Choi , 이남식 Nam-sik Lee , 김복기 Bok-ki Kim
DOI: JANT Vol.24(No.2) 134-141, 2020
Telemetry system is a communication system that measures and transmits various signals in the aircraft to the ground for collecting and monitoring flight data during the development of unmanned air vehicle and satellite launch vehicles. With the recent development of wireless communication technology, it is becoming important to apply encryption of telemetry system to prepare with security threats that may occur during flight data transmission. In this paper, we suggested and implemented the application method of ARIA-256, Korean standard encryption algorithm, to apply encryption to telemetry system. In consideration of the block error propagation and the telemetry frame characteristics, frame is encrypted using the CTR mode and can apply the Reed-solomon codes recommended by CCSDS. ARIA algorithm and cipher frame are implemented in FPGA, and simulation and hardware verification system confirmed continuous frames encryption.
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Miniaturized CPW-fed Folded Slot Antenna
우희성 Hee-sung Woo , 신동기 Dong-gi Shin , 이영순 Young-soon Lee
24(2) 142-147, 2020
우희성 Hee-sung Woo , 신동기 Dong-gi Shin , 이영순 Young-soon Lee
DOI: JANT Vol.24(No.2) 142-147, 2020
In the present study, we proposed newly a CPW-fed miniaturized folded-slot antenna with open ended slot for WCDMA (1.92 ~ 2.17 GHz) band. Open-ended slots and asymmetric ground plane are used for a miniaturization of the antenna, and the proposed antenna was designed and fabricated on a FR-4 substrate with dielectric constant 4.3, thickness of 1.6 ㎟, and size of 35× 70 ㎟. The measured impedance bandwidths (|S11 ≤ -10 dB) of fabricated antenna is about 400 MHz (1.86 ~ 2.26 GHz), which sufficiently satisfied interested band. Furthermore, the gain of antenna is 2 dBi and this antenna shows a similar radiation patterns of the dipole antenna. Therefore, it is expected to be used usefully in wireless and mobile communication device.
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Deep Learning-based Automatic Wrinkles Segmentation on Microscope Skin Images for Skin Diagnosis
최현영 Hyeon-yeong Choi , 고재필 Jae-pil Ko
24(2) 148-154, 2020
최현영 Hyeon-yeong Choi , 고재필 Jae-pil Ko
DOI: JANT Vol.24(No.2) 148-154, 2020
Wrinkles are one of the main features of skin aging. Conventional image processing-based wrinkle detection is difficult to effectively cope with various skin images. In particular, Wrinkle extraction performance is significantly decreased when the wrinkles are not strong and similar to the surrounding skin. In this paper, deep learning is applied to extract wrinkles from microscopic skin images. In general, the microscope image is equipped with a wide-angle lens, so the brightness at the boundary area of the image is dark. In this paper, to solve this problem, the brightness of the skin image is estimated and corrected. In addition, We apply the structure of semantic segmentation network suitable for wrinkle extraction. The proposed method obtained an accuracy of 99.6% in test experiments on skin images collected in our laboratory.
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Deep Learning-based Action Recognition using Skeleton Joints Mapping
타스님 Nusrat Tasnim , 백중환 Joong-hwan Baek
24(2) 155-162, 2020
타스님 Nusrat Tasnim , 백중환 Joong-hwan Baek
DOI: JANT Vol.24(No.2) 155-162, 2020
Recently, with the development of computer vision and deep learning technology, research on human action recognition has been actively conducted for video analysis, video surveillance, interactive multimedia, and human machine interaction applications. Diverse techniques have been introduced for human action understanding and classification by many researchers using RGB image, depth image, skeleton and inertial data. However, skeleton-based action discrimination is still a challenging research topic for human machine-interaction. In this paper, we propose an end-to-end skeleton joints mapping of action for generating spatio-temporal image so-called dynamic image. Then, an efficient deep convolution neural network is devised to perform the classification among the action classes. We use publicly accessible UTD-MHAD skeleton dataset for evaluating the performance of the proposed method. As a result of the experiment, the proposed system shows better performance than the existing methods with high accuracy of 97.45%.
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