• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.6
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• pp.113-119
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• 2017

The Rich Communication Service(RCS) is a next generation mobile messaging service. Since it has been developed and managed by a wireless service provider, 3rd party application developers cannot utilize the RCS features in their apps. A few studies have been proposed to solve this problem, even though they were not viable level of deployment. This paper presents a Web-based Rich Communication Service Software Framework(WebRSF) to help the 3rd party application developers adopt RCS features easily. WebRSF converts complicated RCS protocols to simple web-based protocols for providing the RCS 1-to-1 chat service to the 3rd parties. Communication protocols between WebRSF and its clients are defined in this paper. Also, a network configuration diagram and a message flow diagram are defined. Finally, performance evaluation between the WebRSF client and the RCS client are performed to simulate the load on clients' devices. It shows that the WebRSF client has 17% less loads than the RCS client while initiating sessions, and has 25% more loads after initiating sessions.

• Journal of Communications and Networks
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• v.15 no.5
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• pp.504-513
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• 2013

Communication in delay tolerant networks (DTNs) relies on message transport by mobile nodes, and a correct understanding of the node mobility characteristics is therefore crucial to the design of an efficient DTN routing protocol. However, previous work has mainly focused on uncovering all behaviors of node movement, which is not conducive to accurately detecting the specific movement characteristics of a different node. In this paper, we seek to address this problem based on a consideration of social relationships. We first consider social ties from both static and dynamic perspectives. For a static perspective, in addition to certain accidental events, social relations are considered for a long time granularity and tend to be stable over time. For a dynamic perspective, social relations are analyzed in a relatively short time granularity and are likely to change over time. Based on these perspectives, we adopted different efficient approaches to dividing node pairs into two classes, i.e., familiar and unfamiliar pairs. A threshold approach is used for static social ties whereas a density-based aggregation method is used for dynamic social relationships. Extensive experimental results show that both familiar and unfamiliar node pairs have the same inter-contact time distribution, which closely follows a power-law decay up to a certain point, beyond which it begins to exponentially decay. The results also demonstrate that the inter-contact time distribution of familiar pairs decays faster than that of unfamiliar pairs, whether from a static or dynamic perspective. In addition, we also analyze the reason for the difference between the inter-contact time distributions of both unfamiliar and familiar pairs.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.2
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• pp.86-94
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• 2010

This paper proposed an authentication interworking protocol (AIP) based on IEEE 802.21 MIH in the heterogeneous networks. The proposed AIP using the RSA signature reduces handover delay time and communication message overhead when the mobile node moves between the heterogeneous networks. It defines new AIP TLV in MIH frame format and uses the MIH Information Server (MIHIS) for proxy signature issue instead of the authentication server for the heterogeneous networks. For low handover delay, the proposed AIP performs pre-authentication processes with MIH protocol before layer 2 handover. Also, this paper analyzed the performance of the handover and compared with the non-secure MIH protocol.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.953-958
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• 2015

Raspberry Pi is a credit card-sized computer with support for a large number of input and output peripherals. This makes it the perfect platform for interaction with many different devices and for usage in a wide range of applications. When combined with Wi-Fi, it can communicate remotely, therefore increasing its suitability for the construction of wireless sensor nodes. In addition, data processing and decision-making can be based on artificial intelligence, what is performed in developed testbed on the example of monitoring and determining the confidence of fire. In this paper, we demonstrated the usage of Raspberry Pi as a sensor web node for fire-safety monitoring in a building. When the UV-flame sensors detect a flame as thin as that of a candle, the Raspberry Pi sends a push-message to notify the assigned smartphone of the on-site situation through the GCM server. A mobile app was developed to provide a real-time video streaming service in order to determine a false alarm. If an emergency occurs, one can immediately call for help.

• Journal of Korean Academy of Nursing
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• v.50 no.2
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• pp.242-254
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• 2020

Purpose: The purpose of this study was to examine the effects of smart-phone app-based walking exercise programs for taxi drivers on self-efficacy and outcome expectations for exercise, health-related quality of life, walking as an exercise, and physiological indexes. Methods: A nonequivalent control group with a pre-post-test design was used. The subjects were recruited in G metropolitan city. Subjects were assigned to the experimental (n=31) or control groups (n=30). The smart phone app-based walking exercise program consisted of educations via the app, twelve short message services, and one individual telephone counseling session, which was spread over 12 weeks. Results: Self-efficacy, outcome expectations, and health-related quality of life had significantly higher pre-post test differences in scores in the experimental group. Additionally, blood pressure, body mass index, and waist circumference had significantly decreased prepost-test difference levels in the experimental group. Walking as an exercise (which consisted of days walked, number of steps walked, and amount of time walked) had significantly increased in the experimental group after 7~12 weeks in the period following the intervention program rather than 1~6 weeks after the program. Conclusion: The smart phone app-based walking exercise program based on the self-efficacy theory demonstrates a significant effect on improving self-efficacy, outcome expectations physical activities, and health-related quality of life for taxi drivers. Therefore, it is recommended to actively use the program as a tool to promote self-efficacy, physical activities, and health behaviors in taxi drivers.

• Journal of Advanced Navigation Technology
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• v.11 no.2
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• pp.154-162
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• 2007

This paper verifies the performance of the wireless-signal map-matching (WSMM) method that is recently proposed to mitigate the effects of non-line-of-sight (NLOS) error in positioning under wireless terrestrial network environments. The WSMM method is the new positioning technology that estimates and compensate the NLOS errors by processing the bulks of anonymous measurements at unknown locations that are collected randomly and automatically. The WSMM method would be advantageous for various configurations of future ubiquitous sensor networks since it is based on the existing network configuration for communication and it requires no additional hardware in base stations and mobile handsets. It is shown that the application of the WSMM concept to the real CDMA pilot strength measurment message (PSMM) actually mitigates the NLOS error effects and improves overall positioning accuracy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5B
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• pp.413-420
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• 2006

HMIPv6 is designed to reduce the signaling load to external network and improve handover speed of MN by including Mobility Anchor Point(MAP) in local handover. However in this case of macro handover, it's just used pervious MIPv6 handover algorithm. So, it occurs packet loss and transmission delay problem. In this paper, we propose the mechanism applying the HMIPv6 for Fast Handover to choose suitable to the condition buffering handover. The condition for the selection is result distance measurement between MN and CN, between MN and NAR. Furthermore, using F-SNOOP protocol, it is possible to improve wireless network performance. Wireless network has high Bit Error Rate(BER) characteristic because of path loss, fading, noise and interference. TCP regards such errors as congestion and starts congestion control. This congestion control makes packet transmission rate low. However, F-SNOOP improves TCP performance based on SNOOP and Freeze TCP that use Zero Window Advertisement(ZWA) message when handoff occurs in wireless network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.11
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• pp.1011-1019
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• 2012

This paper presents a novel hybrid authentication scheme in the next-generation Tactical Mobile Communication Systems(TMCS) with wireless MSAP mesh networks. The existing centralized and distributed authentication methods for security between MSAPs may have their pros and cons. The centralized authentication method induces overhead from frequent MSAP association which leads to long authentication delay. On the other hand, the distributed authentication method requires initial sharing of the authentication information. Therefore, a more efficient authentication scheme is needed to protect the network from malicious MSAPs and also maximize efficiency of the network security. The proposed scheme provides a hybrid method of efficiently managing the authentication keys in the wireless MSAP mesh network to reduce the induced authentication message exchange overhead. Also, as the authentication method between MSAP and TMFT is different, a method of utilizing the ACR for handling the EAP packets is proposed. In overall, the proposed scheme provides efficient mutual authentication between MSAPs especially for tactical environments and is analyzed through performance evaluation to prove its superiority.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1B
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• pp.21-28
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• 2011

The femtocell is a miniaturized Base Station (BS) with low-cost and low-power using general broadband access network as backhaul. It is expected not only to improve indoor coverage but also to reduce a service charge. However, in IEEE 802,16e femtocells, when the Mobile Station (MS) scans neighbor BSs for handover, it takes a long time due to too many number of femto BSs. Also the size of the neighbor advertisement message that will be periodically sent by a serving BS is increased as the number of target femto BSs for scanning increases. In this paper, we proposed an efficient femtocell scanning scheme, using a triangulation mechanism and a femto BS monitoring scheme to reduce the number of scanning operations and the size of the neighbor advertisement messages. The proposed scheme can avoid wasting air resources and reduce scanning overheads by minimal scanning operation. The simulation results showed that the proposed scheme could improve scanning performance and avoid wasting air resources, compared with the conventional scheme of the IEEE 802.16e system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.10
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• pp.859-876
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• 2012

Since the existing protocols separated mobility management part and routing protocol part in their design and used a flooding, they suffer from the high control overhead, thereby limiting performance. In this paper, we use a tree-based mobility management method and present a simple and efficient routing protocol that exploits the topology information which is built additionally through mobility management. Thus, the mobility management and the routing protocol closely cooperate to optimize control overhead. Furthermore, we use a progressive path discovery method to alleviate traffic congestion around IG and a unicast-based broadcast method to increase the reliability of message delivery and to judge link validity promptly. The proposed protocol reduces control overhead greatly and works in a stable manner even with the large number of nodes and high mobility. This was proven by comparing with the AODV protocol that employs the hybrid mobility management protocol.