• Journal of the Society of Disaster Information
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• v.14 no.3
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• pp.315-324
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• 2018

Purpose: This paper propose a temporary indoor positioning scheme with devices of internet of things (IoT) for disastrous situations in places without the infrastructure of networks. Method: The proposed scheme is based on the weighted centroid localization scheme that can estimate the position of a target with simple computation. Results: It also is implemented with the IoT devices at the underground parking lot, where the network is not installed, of general office building. According to the experiment results, the positioning error was around 10m without a priori calibration process at $82.5m{\times}56.4m$ underground space. Conclusion: The proposed scheme can be deployed many places without the infrastructure of networks, such as parking lots, warehouses, factory, etc.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.1
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• pp.289-294
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• 2019

It easily collects information on purchased goods using IoT(Internet of Things). The collected data is updated directly to the smartphone for verification. The payment information is generated by QR-Code. As a way to implement a system, System was configured with two assumptions: IoT technology using Raspberry-Pi and mobile QR technology. First, RFID tags are attached to the goods instead of barcodes. Second, it has an IoT computer(Raspberry-Pi) built into its shopping cart. This system keeps traditional shopping method of face-to-face payment, but replace time-consuming tarditional barcode tagging method to QR-tagging system for time-efficiency. By debeloping the system of this paper, we maintain pleasures in offline store shopping and it provide convenience due to reduced waiting time for customers and providing prior information about the products.

• Journal of the Korea Society of Computer and Information
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• v.25 no.10
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• pp.125-133
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• 2020

In this paper, we design 4-layer TCP/IP that utilizes minimal memory and processor resources in Internet of Things(IoT) systems. The TCP/IP designed in this paper has the following characteristics. First, memory resource is minimized by using minimal memory allocation. Second, processor resource is minimized by using minimal memory copy. Third, the execution time of the TCP/IP can be completed in a deterministic time. Fourth, there is no memory leak problem. The standard in minimal resources for memory and processor derived in this paper can be used to check whether the network subsystems of the already implemented IoT systems are efficiently implemented. As the result of measuring the amount of memory allocation and copy of the network subsystem of Zephyr, an open source IoT kernel recently released by the Linux Foundation, we found that it was bigger than the standard in minimal resources derived in this paper. The network subsystem of Zephyr was improved according to the design proposed in this paper, confirming that the amount of memory allocation and copy were decreased by about 39% and 67%, respectively, and the execution time was also reduced by about 28%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.12
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• pp.2347-2356
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• 2017

Raspberry Pi has been widely used for a hardware platform to develop the Internet of Things (IoT) applications. The basic task of diverse IoT devices is to obtain their status or environmental information by using various sensors and to send them to a gateway or a remote server. For the purpose, one of application layer protocols for IoT, MQTT is widely used. IoT devices are often powered by batteries and they are required to operate for a long time without replacing or recharging their batteries. Thus, energy efficiency is one of the most critical problems for obtaining and sending sensor data. To develop energy-efficient IoT applications, the information about power consumption characteristics of the applications is necessary. However, there has been little study to analyze power consumption of IoT communication on IoT devices. This paper presents a study to measure and analyze the power consumption of sending/receiving data under various conditions via the MQTT protocol on Raspberry Pi.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.4
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• pp.1147-1161
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• 2023

The Internet of Things (IoT) requires a new processing model that will allow scalability in cloud computing while reducing time delay caused by data transmission within a network. Such a model can be achieved by using resources that are closer to the user, i.e., by relying on edge computing (EC). The amount of IoT data also grows with an increase in the number of IoT devices. However, building such a flexible model within a heterogeneous environment is difficult in terms of resources. Moreover, the increasing demand for IoT services necessitates shortening time delay and response time by achieving effective load balancing. IoT devices are expected to generate huge amounts of data within a short amount of time. They will be dynamically deployed, and IoT services will be provided to EC devices or cloud servers to minimize resource costs while meeting the latency and quality of service (QoS) constraints of IoT applications when IoT devices are at the endpoint. EC is an emerging solution to the data processing problem in IoT. In this study, we improve the load balancing process and distribute resources fairly to tasks, which, in turn, will improve QoS in cloud and reduce processing time, and consequently, response time.

• Journal of Advanced Navigation Technology
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• v.26 no.6
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• pp.481-486
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• 2022

The recent rapid growth of the IoT(Internet of Things) is leading to the spread of low-power wireless technology. A major challenge in designing IoT wireless networks is to achieve coexistence between different wireless technologies that share the 2.4 [GHz] ISM (Industrial Scientific Medical) frequency band. Therefore, there is a need for research on improving the reliability of wireless networks and coexisting operation between wireless networks. In particular, it is necessary to study an interference model and performance for mutual service coexistence in a BLE (Bluetooth Low Energy) wireless network environment, which is expected to be widely used as a connection medium between devices in various industrial fields. In this paper, the co-channel interference model with the IEEE 802.15.4 system is established focusing on the physical layer of the BLE system widely used in residential and industrial wireless applications, and the performance of the BLE wireless communication system is analyzed in the co-channel interference environment. As a result of the analysis, as the distance between the interference source and the BLE system increases in an environment where noise and co-channel interference exist, the amount of co-channel interference decreases and the error rate performance of the BLE system improves.

• Journal of Communications and Networks
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• v.17 no.6
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• pp.647-655
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• 2015

Low-power and lossy networks (LLNs) comprised of thousands of embedded networking devices can be used in a variety of applications, such as smart grid automated metering infrastructures (AMIs) and wireless sensor networks. Connecting these LLNs to the Internet has even greater potential, leading to the emerging concept of the Internet of Things (IoT). With the goal of integrating LLNs into IoT, the IETF has recently standardized RPL and 6LoWPAN to allow the use of IPv6 on LLNs. Although there already exist several studies on the the performance of RPL and embedded IPv6 stack in LLN, performance measurement and characterization of TCP over RPL in multihop LLNs is yet to be studied. In this article, we present a comprehensive experimental study on the performance of TCP over RPL in an embedded IPv6-based LLN running over a 30-node multihop IEEE 802.15.4 testbed network. Our results and findings are aimed at investigating how embedded TCP interoperates with common Linux TCP and underlying RPL (and vice versa), which furthers our understanding of the performance trade-offs when choosing TCP over RPL in IPv6-based LLNs.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.8
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• pp.58-65
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• 2014

A recent issued Internet of Things (IoT) is based on the service that everything around us is exchanging the information and reacting upon these information. These IoT services are mainly dealing with the information that was generated by the information nodes of IoT networks such as sensors, where the way how the information from information nodes should be dealt with is very important in terms of service reliability in IoT networks. This paper introduces a new scheme for service reliability and energy efficiency that is reducing the energy consumption of actuator node reacting upon the request messages from the information nodes in IoT networks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.503-506
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• 2015

In accordance with IoT(Internet of Things) commercialization, the need to design SoC-based hardware platform with wireless communication is increasing. This paper therefor proposes an SoC platform architecture with Smart Frame System inter-communicating between devices. Wireless communication functions and high-performance real-time image processing hardware structure was applied to existing digital photo frame. We developed a smart phone application to control the smart frame through Bluetooth communication. The SoC platform hardware consists of CIS controller, Memory controller, ISP(Image Signal Processing) module for image scaling, Bluetooth Interface for inter-communicating between devices, VGA/TFT-LCD controller for displaying video. The Smart Frame System to support the IoT services was implemented and verified using HBE-SoC-IPD test board equipped with Virtex4 XC4VLX80 FPGA. The operating frequency is 54MHz.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.5
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• pp.761-768
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• 2023

In the 4th Industrial Revolution, AI(Artificial Intelligence) and IoT(Internet of Things) technologies are being applied to across various fields, with particularly prominence in asset management, disaster management, and meteorological observation. In these fields, it is necessary to accurately determine the real-time and precise tracking of the object's location and status, and to collect various data even in situations that are difficult to detect with existing sensors. In order to address these demands, the use of GNSS(Global Navigation Satellite System) is essential, and this technology enables the efficient management of assets, disaster prevent and response, and accurate weather forecasting. In this paper, we provide the investigated results for the latest trends in the application of GNSS in the fields of asset management, disaster management, and weather observation, among various fields incorporating AI and IoT and analyze them.