• Review of KIISC
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• v.25 no.2
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• pp.35-42
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• 2015

현재 우리 사회는 산업혁명(오프라인), 정보화혁명(온라인)을 거쳐 모든 것이 인터넷과 연결되는 사물인터넷(IoT) 기반의 초연결혁명으로 진화하고 있다. 이에 사물인터넷 디바이스 사업자가 제품을 보다 쉽게 인터넷과 연결할 수 있는 사물인터넷 서비스 표준플랫폼에 대한 수요가 높아지고 있다. 본 문서는 스마트마이크로그리드 및 웰니스 응용서비스와의 연동자동화, 지능화를 위한 IoT 브로커(Broker) 시스템의 기능 요구 사항 및 시스템 요구사항을 분석하고 정의한다.

• Journal of Internet of Things and Convergence
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• v.10 no.2
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• pp.131-135
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• 2024

In the MQTT protocol, if the retained flag of a message published by a publisher is set, the message is stored in the broker as a retained message. When a new subscriber performs a subscribe, the broker immediately sends the retained message. This allows the new subscriber to perform updates on the current state via the retained message without waiting for new messages from the publisher. However, sending retained messages can become a traffic overhead if new messages are frequently published by the publisher. This situation could be considered an overhead when new subscribers frequently subscribe. Therefore, in this paper, we propose a retained message delivery scheme by considering the characteristics of the published messages. We model the delivery and waiting actions to new subscribers from the perspective of the broker using reinforcement learning, and determine the optimal policy through Q learning algorithm. Through performance analysis, we confirm that the proposed method shows improved performance compared to existing methods.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.1-8
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• 2019

Internet of Things (IoT) is proliferating to provide more intelligent services by interconnecting various Internet devices, and TCP based MQTT is being used as a standard communication protocol of the IoT. Although it is recommended to use TLS/SSL security protocol for TCP with MQTT-based IoT devices, encryption and decryption performance degenerates when applied to low-specification / low-capacity IoT devices. In this paper, we propose an end-to-end message security protocol using elliptic curve cryptosystem, a lightweight encryption algorithm, which improves performance on both sides of the client and server, based on the simulation of TLS/SSL and the proposed protocol.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.870-873
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• 2016

최근 IoT 보급이 가속화되면서, 글로벌기업들의 IoT 시장의 주도권 선점을 위한 혁신적 기술력 확보 경쟁이 치열해지고 있다. 사물 인터넷 기술을 지원하는 플랫폼 표준화 작업 외에도, 글로벌 대기업 중심으로 다수의 플랫폼 기술이 난립하고 있으며, 스마트 디바이스 통신에는 MQTT, CoAP, XMPP, HTTP 등 다양한 프로토콜이 사용되고 있다. 이렇게 다양한 플랫폼과 프로토콜을 사용하는 환경에서 디바이스간의 상호 연동 서비스가 중요한 문제로 대두되고 있다. 본 논문에서는 MQTT, CoAP 등 서로 다른 프로토콜을 사용하는 디바이스 간의 상호 통신을 용이하게 하고 향후 플랫폼 설계에 적용될 브로커 서버의 설계를 제안하고 구현한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.312-313
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• 2017

Internet of Things(IoT) is an intelligent technology and service in which all objects communicate with each other through various networks. Recently Internet of Things(IoT) is one of the fields that is attracting attention as the development of ICT industry. MQTT is a protocol which is safe using TLS or adopting light packet structure for effciency of memory and power using. In this paper, when TLS is used the process of encryption / decryption in the broker occurs. We propose an efficient MQTT protocol through centralized key management by adding authentication server.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.116-118
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• 2018

This paper introduces oneM2M global IoT standard middleware platform based smart city service data model support and FIWARENGSI interworking for Orion Broker. Also, service data models implementation using flexContainer resource types and FIWARENGSI interworking using the Interworking Framework (TS-0033) from oneM2M Release 3 are also illustrated. In this system, data model element level access (e.g. for subscription/notification feature) is enabled, which is enhancement compared to contentInstance resource type before, and service agnostic FIWARE NGSI interworking is provided over the Interworking Framework for smart city platform data interworking.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.744-747
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• 2017

The Internet of things (IoT) needs to be an event-driven approach for efficient real time response and processing. An IoT gateway is sometimes employed to provide the connection and translation between devices and the cloud. Storing data in the local database, and then forwarding it on the cloud is a task to be relegated to a gateway device In this paper, we propose the design of the IoT gateway with Fog computing for storing data from sensors into a local database. In the procedure of designing storing tasks, we propose to use the interfacing software known as Ardulink MQTT bridge. MQTT is a protocol for sensors to publish data to the clients. When it comes to needing historical data, MQTT connector can push MQTT data into SQL database. We write an MQTT client and based on the message topic insert the values into a SQL Database The design of IoT gateway with Fog computing adds value because it provides processing of the data across multiple devices before it sends to the cloud.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.785-788
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• 2016

최근 IoT 프로토콜 가운데 가장 활발히 논의되는 프로토콜로 CoAP(Constrained Application Protocol)이 있다. CoAP은 4가지 보안모드로 운영된다. 그 중 3가지 모드인 PresharedKey, RawPublicKey, Certificate 모드의 경우 DTLS(Datagram Transport Layer Security)가 적용된 방식이다. 반면 NoSec 모드는 DTLS가 적용되지 않은 기본방식이다. 본 논문에서는 DTLS의 복잡한 Handshake 방식으로 인한 전력소모 및 Performance의 저하를 고려한 새로운 방식을 제안한다. NoSec 환경의 CoAP 프로토콜에 S-Broker(Secure-Broker)를 적용한 security 및 performance 향상 방안이다. 제안한 방식으로 경량화 통신을 구현하여 무결성과 보안 강도를 높였다. 추가적으로 Proxy의 forwarding 기능과 caching 기능을 구현하여 성능의 향상을 도모한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.1
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• pp.231-237
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• 2020

In this paper, we implemented a home IoT system based on MQTT protocol. In this system, data are collected from sensors in real time and transmitted to the server system. Based on collected data, home devices could be controlled automatically or manually. By using the MQTT protocol, we were able to see the data values of sensors collected in real time according to the topic setting. We implemented a system that automatically sets up home devices based on topic data, and it worked. The system is expected to be useful in applications that require monitoring and tracking of data in real time.

• Smart Media Journal
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• v.13 no.4
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• pp.76-85
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• 2024

In this paper, we propose a system that improves the data integrity of IoT(Internet of Things) devices in the virtual environment by combining Hyperledger Indy and MQTT(Message Queuing Telemetry Transport). The system complements the limitations of the centralized system by realizing a DPKI(Decentralized Public Key Infrastructure) structure that utilizes a distributed network in publish-subscribe(pub/sub) pattern communication. Digital signature technology was applied to ensure the data integrity of IoT devices and communication scenarios between the four core components of the client, IoT device, broker, and blockchain, as well as a topic structure using a decentralized identifier to ensure safety in the virtual environment. We present a systematic method for transparent data exchange. To prove the performance of the proposed system, this paper conducted experiments on four scenarios and evaluated communication performance in a virtual environment. The experimental results confirmed that the proposed system provides a reliable IoT data communication structure in a virtual environment.