• Journal of Korea Multimedia Society
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• v.24 no.8
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• pp.1101-1113
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• 2021

The rapid growth of sense-and-respond applications and the emerging cloud computing model present a new challenge: providing publish/subscribe middleware as a scalable and elastic cloud service. The publish/subscribe interaction model is a promising solution for scalable data dissemination over wide-area networks. In addition, there have been some work on the publish/subscribe messaging paradigm that guarantees reliability and availability in the face of node and link failures. These publish/subscribe systems are commonly used in information-centric networks and edge-fog-cloud infrastructures for IoT. The IoT has an edge-fog cloud infrastructure to efficiently process massive amounts of sensing data collected from the surrounding environment. In this paper. we propose a quorum-based hierarchical fault-tolerant publish/subscribe systems (QHFPS) to enable reliable delivery of messages in the presence of link and node failures. The QHFPS efficiently distributes IoT messages to the publish/subscribe brokers in fog overlay layers on the basis of proposing extended stepped grid (xS-grid) quorum for providing tolerance when faced with node failures and network partitions. We evaluate the performance of QHFPS in three aspects: number of transmitted Pub/Sub messages, average subscription delay, and subscritpion delivery rate with an analytical model.

• Journal of Korea Multimedia Society
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• v.17 no.12
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• pp.1461-1472
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• 2014

Recently, smart devices has been spreaded and the definition of RFID/USN(Radio Frequency Identification/Ubiquitous Sensor Network) technology has also extended. So, originally, human is an agent of communications but now, 'the things' are also an agent of communication. That is, Internet of Things(IoT). IoT is very big IT infra technology that is based on wire-wireless network technologies such as Bluetooth and Wi-Fi. However, in reality, IoT service that can provide various meaning and integrate smoothly is not appear yet. To solve these problems of IoT, we implemented Publish/Subscribe system, which operate in Zigbee based wireless sensor network by using MQTT-SN protocol. Moreover, this system can operate with combining MQTT system that is already existed in external Internet network so, extensibility and flexibility aspect is excellent. We show that possibility of IoT services that is combined between different heterogeneous network through the MQTT-SN.

• Journal of Korea Multimedia Society
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• v.9 no.6
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• pp.720-727
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• 2006

In this paper, we propose a method which allows the SuperSQL query processor to share as much code as possible among various, generators, each of which is responsible for the output of a certain medium. SuperSQL is an enhanced query-processing system that converts database records into a variety of formats such as XML, HTML, PDF and etc. However, the existing SuperSQL media generator would require creation of a different processor for each medium, causing duplicated development cost. This research makes three main contributions: First, it analyzes the structures of various media, examining any possibility of integration based on their common structure. Second, it also facilitates the addition of a new output media generator by separating constructors and decorators from each medium. Last, it provides an integrated user interface to each media by method of the Media Abstraction Table Concept. We also show the performance and feasibility of our system using experimental results.

• Journal of Korea Multimedia Society
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• v.25 no.8
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• pp.1075-1084
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• 2022

Internet of Things(IoT) has become a key available technology for efficiently implementing device to device(D2D) services in various domains such as smart home, healthcare, smart city, agriculture, energy, logistics, and transportation. A lightweight publish/subscribe(Pub/Sub) messaging protocol not only establishes data dissemination pattern but also supports connectivity between IoT devices and their applications. Also, a Pub/Sub broker is deployed to facilitate data exchange among IoT devices. A scalable edge-based publish/subscribe (Pub/Sub) broker overlay networks support latency-sensitive IoT applications. In this paper, we design a hypercube grid quorum(HGQ) for distributed Pub/Sub systems based IoT applications. In designing HGQ, the network of hypercube structures suitable for the publish/subscribe model is built in the edge layer, and the proposed HGQ is designed by embedding a mesh overlay network in the hypercube. As their applications, we propose an HGQ-based mechansim for dissemination of the data of sensors or the message/event of IoT devices in IoT environments. The performance of HGQ is evaluated by analytical models. As the results, the latency and load balancing of applications based on the distributed Pub/Sub system using HGQ are improved.

• Journal of Korea Multimedia Society
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• v.22 no.8
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• pp.913-922
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• 2019

The Internet of Things (IoT) envisions smart objects collecting and sharing data at a massive scale via the Internet. One challenging issue is how to disseminate data to relevant data consuming objects efficiently. In such a massive IoT network, Mission critical data dissemination imposes constraints on the message transfer delay between objects. Due to the low power and communication range of IoT objects, data is relayed over multi-hops before arriving at the destination. In this paper, we propose a quorum-based adaptive dissemination algorithm (QADA) for the critical data in the monitoring-based applications of massive IoTs. To design QADA, we first design a new stepped-triangular grid structures (sT-grid) that support data dissemination, then construct a triangular grid overlay in the fog layer on the lower IoT layer and propose the data dissemination algorithm of the publish/subscribe model that adaptively uses triangle grid (T-grid) and sT-grid quorums depending on the mission critical in the overlay constructed to disseminate the critical data, and evaluate its performance as an analytical model.

• Journal of Korea Multimedia Society
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• v.18 no.8
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• pp.980-987
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• 2015

Most of cultural area which people enjoy and consume is kitsch culture, though the culture is barely acknowledged. In this multimedia era, people create, publish and enjoy contents of 'webtoon(web+cartoon)', which is relatively faster and more convenient to enjoy comparing to published cartoon. Contrarily to its physical growth, the webtoon shows difficulty in advancing with other genres, is full of irritative factors and contents, and has tough time to become more sophisticated one. This study derived characteristics of kitsch in webtoon, suggested the way of webtoon as an art by analyzing conditions and usage motivation of webtoon. The conditions of kitsch are uniformity of mass consumption, popular vein, catharsis, vicarious satisfaction, immediate feedback-requiring image flood, and reproduction of techniques. The usage motivations of webtoon are studied as pursuit of information, entertainment, relaxation, socialization, convenience, and effectiveness. Usage motivation factors in webtoon and kitsch culture are almost identical. Contrary to its past of being underestimated and vulgarly considered, kitsch is acknowledged as an 'kitsch art'. By studying the process of becoming an art, the study has its purpose to suggest the experimental and developing way to make webtoon be acknowledged as 'webtoon art'.

• Journal of Korea Multimedia Society
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• v.19 no.3
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• pp.650-658
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• 2016

This study proposes web-based authoring system for the lecturers who published textbooks by inserting external open resource. When lecturer publishes textbooks, the system makes it easier to utilize external resources by providing an open resource pool that the lecturer can search not only his own resources but external resources. In addition, we designed an open resource pool based on Original Contents Tracing Model to check whether the scrapped resource is changed or not in the future. Open Resource Pool allows inserting text, images and videos by searching multimedia, and stores metadata for the follow-up management. We made the system to determine the change of the resource using the metadata stored in the tracking system. Through this research, we confirmed that it is possible to publish textbooks by utilizing a variety of open resources on the web and revise the book by tracing the scrapped resources.

• Journal of the Korea Society of Computer and Information
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• v.14 no.7
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• pp.123-132
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• 2009

The perforrnance and portability of mobile applications can be greatly increased by adopting proxy modiles which exists between the conventional system and the device. When mobile devices collaborate with the conventional computers, there are problems to address: a battery life problem, limited input and output methods, and intermittent wireless connection. Those issues are magnified in the multimedia collaboration environment since it works in a real-time condition and the size of the message in the system is big in many cases. Additionally, because multimedia collaboration system softwares are too heavy and complex for mobile devices, it is veη hard to integrate them with conventional systems. In this paper, we describe our design and its implementation of a novel approach to map events (i.e. messages) using a proxy for mobile applications. We adopt a proxy to provide a content adaptation (i.e. transcoding) where the message contents are customized. Also, we design a mobile version publish/subscribe system to provide communication service for mobile device in loosely coupled and flexible manner. We present our empirical results which show that our design can be efficiently implemented and integrated with a conventional multimedia collaboration system.

• Journal of Korea Multimedia Society
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• v.20 no.8
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• pp.1369-1378
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• 2017

Pub/Sub (Publish/Subscribe) paradigm is a simple and easy to use model for interconnecting applications in a distributed environment. In general, subscribers register their interests in a topic or a pattern of events and then asynchronously receive events matching their interest, regardless of the events' publisher. In order to build a low latency lightweight pub/sub system for Internet of Things (IoT) services, we propose a GQSFPS (Group Quorum System-based Fog Pub/Sub) system that is a core component in the event-driven service oriented architecture framework for IoT services. The GQSFPS organizes multiple installed pub/sub brokers in the fog servers into a group quorum based P2P (peer-to-peer) topology for the efficient searching and the low latency accessing of events. Therefore, the events of IoT are cached on the basis of group quorum, and the delay-sensitive IoT applications of edge devices can effectively access the cached events from group quorum fog servers in low latency. The performance of the proposed GQSFPS is evaluated through an analytical model, and is compared to the GQPS (grid quorum-based pud/sub system).

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.01a
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• pp.129-130
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• 2018

본 논문에서는 IoT 환경에서 응용프로토콜로 사용되는 MQTT 프로토콜을 활용한 위치 정보 푸시 알림 서비스 앱 개발 방법과 개발된 앱을 소개한다. MQTT 프로토콜은 Publish/Subscribe 전송 방식을 통해 정보를 제공하는 제공자와 정보를 필요로 하는 클라이언트 사이에 메시지를 전달한다. 본 논문에서는 이런 메시지 전송 방식을 활용한 MQTT 기반 위치 정보 전송이 가능한 앱 개발 방법을 제시한다. 제안하는 방법은 기존 앱에 비해 이동 시 자동으로 위치 정보 알림 서비스를 추가로 구현하였다.