• Journal of Advanced Navigation Technology
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• v.22 no.2
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• pp.76-83
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• 2018

In order to prevent overusing the fishing gear and to reduce discarded fishing gear, there is a need for a technique that can efficiently transmit the information including the type and location of the fishing gear and the user's real name to the fishing boat and the control center using IoT-based communication. In order to do this, it is necessary to be able to confirm the position information of a plurality of buoys that can be identified by the base stations on the land. In this paper, in order to service the maritime IoT communication system, we calculate the link budget between the land base station and the targets on the sea to derive the service coverage. To design a marine IoT radio network for building a fishing gear monitoring system, we calculate link budget for wireless service optimization at sea for NB-IoT using 1.8 GHz frequency band and LoRa service using 900 MHz frequency band. In addition, the link budget between the land base station and buoy, the link budget between the land base station and fishing boat are calculated and the results are analyzed.

• Journal of the Society of Disaster Information
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• v.13 no.4
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• pp.422-441
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• 2017

Notifying emergency evacuation methods, accurate disaster location and evacuation route guidance can be very active alternatives to quickly minimize evacuation and casualties in disaster situation in the development of subway disaster prevention detection system that detects the disaster signs at the subway station early on the basis of Internet of things and leads passengers to evacuate. It's not easy to ensure perfect functioning of fire fighting facilities and equipments due to underground space structure with narrow exits. Therefore, we developed disaster provision EL Display integrated board that can induce the most efficient evacuation and the field experiment was conducted to examine the practical application in this study. Especially the applicability was verified by field application test because there is no case in which EL panels are used to evacuate disasters.

• The Journal of Korean Institute of Information Technology
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• v.16 no.12
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• pp.57-68
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• 2018

A system to prevent disasters by collecting and analyzing environmental information such as road surface sedimentation, sinkholes, collapse risk of bridges, temperature and humidity around tram station is continuously monitored by monitoring the condition of road surface when constructing tram which is one of the urban railways. In this paper, we propose a wireless network security management system for tram roads based on LPWA that can recognize risk factors of road surface, bridge and tram station of tram in advance and prevent risk. The proposed system consists of a sensor node that detects the state of the tram road surface, a gateway that collects sensor information, and a safety management system that monitors the safety and environmental conditions of the tram road surface, and applies the low power long distance communication technology. As a result of comparing the proposed system with the LTE system in the field test, it was confirmed that there is no significant difference between the sensor information value and the critical alarm level in the monitoring system.

• Journal of Practical Engineering Education
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• v.13 no.2
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• pp.321-326
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• 2021

Wireless communication is a core technology constituting the Internet of Things (IoT), but there is no suitable educational equipment to learn various wireless communication technologies used in the Internet of Things through practice. This paper deals with the development of advanced education and training equipment that can perform various IoT wireless communication practices. It uses an Arduino mega board as a device to control various sensors. As wireless network technologies to send and receive the sensing date wirelessly, it makes use of RFID/NFC and Bluetooth among WPAN technologies, WiFi among WLAN technologies and LoRa and 2.4GHz wireless transceiver among WWAN technologies. In addition, GPS, infrared communication, I2C communication, and SPI communication are organized so that various IoT wireless communication technologies can be learned through practice. In addition, since the educational equipment developed in this paper is equipped with two devices, it is designed to perform transmission and reception experiments for wireless network technology within the equipment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.1
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• pp.100-106
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• 2020

In this paper smart shoes for dementia care using embedded boards and Low Power Wide Area technology and their application software are implemented. The communication board composed of Cortex-M3 board and LoRa module is embedded into groove made in outsole of smart shoes. Including the mold, the shoe outsole was manufactured by hand. By using application software and embedded board, caregiver can track the position of dementia patient using GPS and LoRa network. The location tracking and data transmission operations of smart shoes have been successfully verified in the outdoor environment. The smart shoes of this paper are applicable to a safety device to prevent the disappearance of demented patients through results of experiments and if bigdata is collected and analyzed by deep-learning, it may be helpful to analyze the predictive path of dementia patients or the pattern of dementia.

• Journal of the Korea Convergence Society
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• v.7 no.6
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• pp.13-21
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• 2016

In this paper we are trying to explain the effect of temperature on polymer membrane exchange water electrolysis (PEMWE) and polymer membrane exchange fuel cell (PEMFC) simultaneously. A comprehensive studying approach is proposed and applied to a 50Watt PEM fuel cell system in the laboratory. The monitoring process is carried out through wireless LoRa node and gateway network concept. In this experiment, temperature sensor measure the temperature level of electrolyzer, fuel cell stack and $H_2$ storage tank and transmitted the measured value of data to the management control unit (MCU) through the individual node and gateway of each PEMWE and PEMFC. In MCU we can monitor the temperature and its effect on the performance of the fuel cell system and control it to keep the lower heating value to increase the efficiency of the fuel cell system. And we also proposed a mathematical model and operation algorithm for PEMWE and PEMFC. In this model, PEMWE gives higher efficiency at lower heating level where as PEMFC gives higher efficiency at higher heating value. In order to increase the performance of the fuel cell system, we are going to monitor, communicate and control the temperature and pressure of PEMWE and PEMFC by installing these systems in a building of university which is located in the southern part of Korea.

• Journal of information and communication convergence engineering
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• v.16 no.2
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• pp.93-98
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• 2018

The Internet of Things (IoT) is a form of the emerging 4th industry in the 5G era. IoT is expected to develop naturally in our daily life in the 5G era in which high-speed communication will be completed. Along with the rise of IoT, concerns about security and malicious attacks are also increasing. This paper examines DoS attacks, which are one of the representative security threats of IoT and proposes a local detection and blocking system that are suitable for response to such attacks. First, systems of the LoRaWAN type, which are most actively researched in the IoT system field and DoS attacks that can occur in such systems were examined. Then, the inverse order tree algorithm using regional characteristics was designed as a cluster analysis form. Finally, a system capable of defending denial-of-service attacks in the 5G IoT system using local detection and blocking with the Euclidean distance was designed.

• ETRI Journal
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• v.45 no.4
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• pp.570-580
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• 2023

Sensor nodes are the most significant part of a wireless sensor network that offers a powerful combination of sensing, processing, and communication. One major challenge while designing a sensor node is power consumption, as sensor nodes are generally battery-operated. In this study, we proposed the design of a low-power, long range-based wireless sensor node with flexibility, a compact size, and energy efficiency. Furthermore, we improved power performance by adopting an efficient hardware design and proper component selection. The Nano Power Timer Integrated Circuit is used for power management, as it consumes nanoamps of current, resulting in improved battery life. The proposed design achieves an off-time current of 38.17309 nA, which is tiny compared with the design discussed in the existing literature. Battery life is estimated for spreading factors (SFs), ranging from SF7 to SF12. The achieved battery life is 2.54 years for SF12 and 3.94 years for SF7. We present the analysis of current consumption and battery life. Sensor data, received signal strength indicator, and signal-to-noise ratio are visualized using the ThingSpeak network.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.79-85
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• 2017

It is critical that passengers should be given timely and correct escape or evacuation guidance from captain and crews when there are hazardous situations in a ship. Otherwise the consequences could be disastrous as "SEWOL Ferry" the South Korean passenger ship which sank in southern coastal area on 16th April 2014. Due to the captain's delayed evacuation decision and lack of sufficient number of crews to guide passengers' evacuation, the accident recorded many casualties, most of whom were high school students (302 passengers sank down with the ship while 172 rescued). Building a passenger ship with well-designed physical escape routes is one thing and guiding passengers to those escape routes in real disaster situation is another. Passengers get panic and move to a wrong direction, bottleneck makes situation worse, and even crews get panic also - passive static escape route signage and small number of trained crews might not be enough to take care of them. SESS (Smart Escape Support System) is being developed sponsored by South Korea Ministry of Ocean and Fisheries starting from 2016 with 4 years of roadmap. SESS comprises multiple active dynamic signage devices which communicate with real-time escape routing server software via LoRa (Long Range) proprietary wireless network.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1373-1378
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• 2018

In order to solve the problems such as reduction of agriculture population, aging and declining of grain self sufficiency rate, agriculture ICT convergence technology utilizing IoT technology is actively being developed. Agricultural ICT technology only concentrates on facility houses, and there is no automated control system in the field of cultivation. In this paper, we propose an irrigation control system that automatically controls the solenoid valves and water pumps in a large area with Lora wireless communication. The proposed system does not require a separate power source by using a small solar panel, and it is very convenient to install and operate supporting wireless auto setup by plug-and-play method. Therefore, it is expected that it will contribute to the reduction of labor force, quality of agricultural products, and productivity improvement.