• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.3
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• pp.433-439
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• 2021

In this paper, we propose a method to implement an IoT-based sensor network for each workplace of a shipyard. Here, at the most common welding workplace in shipyards, the shipbuilding blocks are used as a communication medium to transmit information such as the worker's location, welding progress, and working hour to a server using LoRa and powerline communication. To achieve the data communication, inductive couplers and hybrid modems have been manufactured and installed on wire feeders and pin jigs to establish a sensor network. As a result of field test, the proposed system shows a success rate of data transmission and a rate of successful recognition of worker's location of about 98% or more. In addition, the process management system platform can record and display the work process data generated at the field in real time. The proposed system can be a starting point for enhancing the competitiveness of Korean shipbuilding industry through the establishment of a smart shipyard.

• Journal of Internet Computing and Services
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• v.20 no.1
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• pp.11-16
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• 2019

Wireless sensor network is important for precision farming to monitor the growth environment of crops in open field, but radio signals are susceptible to different types of interference such as weather and physical objects. This paper designs and implements an environmental monitoring and weather forecast acquisition systems for smart field irrigation based on LoRa(Long Range) and then applies it to a test bed. And we evaluate the network reliability in terms of packet transmission success rate by comparing its condition on two criteria; the existence of obstacle or rain. The results show that much rain falls can affect on packet loss in LoRa field networks with obstacles.

• 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.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.676-678
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• 2021

This paper shows the design of edge device for marine and industry IoT sevice. Edge device gather IoT sensing data and then send these data into external network. For transmitting the gathered data, commercial LoRa and LTE Cat.M1 are applied into the edge device.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.2
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• pp.239-250
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• 2022

LoRa is a physical layer technology designed to secure highly reliable long-range communication with introducing loco parentis tree network and chirp spreading spectrum. Since since a leaf can send message to more than one parents simultaneously with a single transmission in a region, packet delivery ratio increases logarithmically as the number of gateways increases. The delivery ratio, however, dramatically collapses even under loco parentis tree topology due to the limitations of ALOHA-like primitive MAC, . The proposed method is intended to exploit SDMA approach to reuse frequency in an area. With the view, TxPower of each sender for each message in a concurrent transmission is elaborately controlled to survive the collision at different gateway. Thus, the gain from the capture effect improves the capacity of resource-hungry Low Power and Wide Area Networks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.194-198
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• 2021

LoRa is a physical layer technology that is designed to provide a reliable long-range communication with introducing CSS and with introducing a loco parentis tree network. Since a leaf can utilize multiple parents at the same time with a single transmission, PDR increases logarithmically as the number of gateways increases. Because of the ALOHA-like MAC of LoRa, however, the PDR degrades even under the loco parentis tree topology similarly to the single-gateway environment. Our proposed method is aimed to achieve SDMA approach to reuse the same frequency in different areas. For that purpose, it elaborately controls each TxPower of the senders for each message in concurrent transmission to survive the collision at each different gateway. The gain from this so-called capture effect increases the capacity of resource-hungry LPWAN. Compared to a typical collision-free controlled-access scheme, our method outperforms by 10-35% from the perspective of the total count of the consumed time slots. Also, due to the power control mechanism in our method, the energy consumption reduced by 20-40%.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.613-619
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• 2020

Hybrid media access control (MAC) is used in internet of things (IoT) network, because of communication feature concern with data capacity and communication interval between gateway and sensor nodes and the cost efficiency. Hybrid MAC consists of TDMA and CSMA generally. The distance between gateway and sensor node is openly changed in marine IoT network. Therefore, it is needed to control the period of timeslot of hybrid MAC used in marine IoT network. In this paper, the design rule of TDMA timeslot with the variable period depending on communication distance was proposed. It was confirmed from the analysis that 72 times communication between gateway and sensor nodes is possible in LoRa network by using the proposed TDMA variable timeslot scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.2
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• pp.173-178
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• 2019

Recently, the types and amount of data generated, collected, and measured in IoT such as smart home, security, and factory are increasing. The technologies for IoT service include sensor devices to measure desired data, embedded software to control the devices such as signal processing, wireless network protocol to transmit and receive the measured data, and big data and AI-based analysis. In this paper, we focused on developing a gateway for interfacing heterogeneous sensor network protocols that are used in various IoT devices and propose a heterogeneous network interface IoT gateway. We utilized a OpenWrt-based wireless routers and used 6LoWAN stack for IP-based communication via BLE and IEEE 802.15.4 adapters. We developed a software to convert Z-Wave and LoRa packets into IP packet using our Python-based middleware. We expect the IoT gateway to be used as an effective device for collecting IoT big data.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.1
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• pp.47-52
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• 2017

This study is BIT(: Bus Information Terminal) features that take advantage of KEPCO eIoT(: energy Internet of Thing) platform, and it's Network configuration is composed of display terminal device, gateway, platform, and the service server. The key features are parts for processing protocol data between the gateway and the device using LoRa(: Long Range) technology, Intelligent applications and SIP(: Session Initiation Protocol) data handling connected to the Taxi reservation system. And the resource tree provided BIT for the service, which commonly used in the application server and the device.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.11
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• pp.1107-1112
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• 2016

This study is the Smart Office features that take advantage of KEPCO eIoT(: energy Internet of Thing) platform, and it's Network configuration is composed of sensing device, gateway, platform, and the service server. The key features are parts for processing protocol data between the gateway and the device using LoRa(: Long Range) technology, Intelligent applications and public safety data connected to the PS-LTE(: Public Safety-Long-Term Evolution) system. And the resource tree provided Smart Office for the service, which commonly used in the application server and the device.