Dongwoo Kwon

Mobile network configuration for large-scale multimedia delivery on a single WLAN

We report performance measurements and analyses of a variety of wireless networks to arrive at an appropriate network structure configuration for smooth multimedia streaming service with a variety of smart devices in a single wireless network environment. Unlike the usual infrastructure network, configurations such as the IEEE 802.11 ad hoc network and the Wi-Fi direct network use direct connections between devices without going through a wireless AP. Therefore, these configurations prevent concentrating traffic at the wireless AP. We generated three types of wireless network performance measurements and arrived at a suitable network for multimedia streaming service using a variety of smart devices. The wireless network was configured in a structure for efficient multimedia streaming service in a single wireless LAN environment, and subsequently, the network performance was measured.

Development of a gateway system for social network services

In this paper, we propose a method to reduce mobile social network services (SNSs) traffic using a mobile integrated SNS gateway (MISG) to improve network communication performance between the mobile client and SNS servers. The gateway connects the client and SNS servers using the contents adapter and the web service adapter and helps to improve communication performance using its cache engine. An integrated SNS application, the users client, communicates with the gateway server using integrated SNS protocol. In addition, the gateway can alert the client to new SNS contents because of the broker server implemented by the message queuing telemetry transport protocol. We design and develop the modules of the gateway server and the integrated SNS application. We then measure the performance of MISG in terms of content response time and describe the result of the experiment.

Design of an effective framework for mash-up service development

With the advance of wireless communication technology, new computing technologies such as cloud computing, mobile computing, IoT, and etc. have been emerged. Based on emerging technologies, a variety of services have been provided for users. The mash-up service means a way to generate a new service by mixing more than two of existing services. Since service developers exploit existing services to make a new service, the efficiency of the development has improved and the period of development decreased as well as the new service fulfill the various requirements. So far, simple mash-up services have been developed, but it is difficult for developers to generate complex mash-up service. In this paper, we proposed framework design for efficient mash-up service development. The proposed framework is designed to satisfy complex and various service requirements. We designed a service scenario called as Campus Safety Management Mash-up Service (CSMMS) to evaluate the feasibility of the proposed framework.

Development of gate security system based on mash-up framework

Variety of types of security systems have been utilized in a lot of places such as government office, company, and etc. Among them, gate security system is a representative security system. In the existing gate security systems, ID card or biometrics is frequently exploited for identification and authorization. ID card based gate security system is widely adopted, but it is vulnerable to replication and modification of the ID card. Biometrics based gate security system has no weakness of replication and modification, but it requires high complexity and shows the high false identification ratio rather than ID card based system. In this paper, we proposed gate security system based on mash-up framework. In our scheme, both ID card and biometrics are utilized to prevent the use of forged ID card and to increase the ratio of identification. We implemented the proposed scheme for performance evaluation, and our proposed scheme shows better performance than the existing gate security systems.

A synchronized playback method with dynamic buffering time awareness for media streaming

We propose a synchronized playback method for the real-time synchronization of the playback position of streaming media to multiple clients from a streaming server. The playback-related information that is used in this synchronized playback method comprises the current time and the playback position, and the server transmits the playback position and the current time to the client. The client can determine the playback position of the server based on the playback position and the current time and can synchronize playback using this information. In this paper, we describe the configuration of the experimental environment for synchronized media playback and present the synchronization algorithms used in this method for both the server and the client. Then, we present a method for measuring the synchronization accuracy and the results of such measurements. The average synchronization accuracy is 26 msec. According to the Haas effect, the experimentally measured sync accuracy is sufficiently high that the corresponding sound error is not detectable by the human ear.

DDoS attack volume forecasting using a statistical approach

In this paper, we propose a proactive security method that estimates distributed denial of service (DDoS) attack volume in order to overcome the limitation of the response time of reactive security systems based on intrusion detection. To that end, we define and discuss network intrusion forecasting and intrusion factors in comparison to intrusion detection. Intrusion factors for a DDoS attack are also analyzed and collected from the Honeynet system. Based on the data from the Honeynet system, we conduct correlation and regression analysis, both statistical approaches, to predict the potential DDoS attack volume for the network security of our university. By combining network intrusion detection with intrusion forecasting, network operators can take active countermeasures based on the forecasting results and strengthen the network security.

Chemical laboratory safety management service using IoT sensors and open APIs

In this paper, we propose a safety management service using Internet of Things (IoT) for accidents prevention and management. The reason for applying IoT technology in the service is that it is can be used to semi-automate the service through the IoT sensors, and it is useful to the experimenter with chemicals. We describe the requirements and architecture of our proposed service.

A robust group synchronization approach to network congestion based on control events for media streaming

We developed a robust approach that can be synchronized with accuracy to a media streaming group in a network congestion situation. This approach consists of a server-side and client-side algorithm. The server-side algorithm is used to transmit the playback information using a synchronization control packet to clients. The synchronization control packet is transmitted in an event-driven manner. The clientside algorithm synchronizes the playback position by using the information received from the server. The detailed algorithm is used to accurately synchronize the playback position on the client. Finally, we measured the synchronization accuracy according to the network congestion. The performance results of this experiment can improve the completion time and the synchronization accuracy in network congestion.

Design of a media stream relay engine on the Android OS

The hierarchical network structure is proposed as a solution to the problem of decreased network performance for large-scale multimedia delivery in a single wireless LAN environment. However, the network structure on the Android OS is used for media streaming service; the role of the source device is important because a group owner delay causes a performance problem in which streaming data transmission to all Wi-Fi direct network groups creates a bottleneck. For a solution to these problems, we propose the media stream relay engine architecture and describe sequence diagrams for the development of a relay engine on the Android OS.

A media distribution tree construction method using a maximum spanning tree for mobile smart devices

In this paper, we propose a Media Distribution Tree (MDT) construction method to provide efficient multimedia streaming service between mobile smart devices in mobile ad hoc networks. An MDT for efficient media streaming is constructed based on a maximum spanning tree, which considers device hardware performance, energy and wireless network state to determine media stream relay nodes. The MDT represents the media streaming paths among mobile smart devices and connects a group owner device and group member devices. Finally, we measure network bandwidth and round-trip time on the media streaming network, which follows the constructed MDT using the proposed method, and analyze the experiment results.