• The Journal of Information Systems
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• v.23 no.1
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• pp.73-91
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• 2014

Microblog is emerging as a new communication service because of its usefulness and real-time accessability. Recently, microblog services, such as twitter and me2day in Korea, are getting a great attention. Continuous use intention is critical to sustain the service. However, most recent studies are based on Technology Acceptance Model(TAM) and Expectation Confirmation Model(ECM). These models are only focused on individual factors and overlook social influence factors. Social influence has been indicated as a critical factor of technology adoption and diffusion in social context(Davis, 1989; Fulk et al., 1987). In this study, we explore factors related to social influence which effect on continuous use intention for 'me2day' that is one of the most famous microblog in Korea. The purpose of this study is to understand continuous use intention and examine the relationship among social influence factors, social presence, and continuous use intention. To understand the phenomenon of continuous use intention in microblog service, this study employed social influence theory and expanded it by adding personal network exposure and group norm as additional social influence factors. The results show that social identity, group norms, and social presence positively influences continuous use intention. Contrary to our expectation, personal network exposure does not influence on continuous use intention. Academically, this research can contribute to microblog research field through elucidating the relationship among social influence factors, social presence, and continuous use intention. Although there is not enough research which is considered social influence factors as major explanation for continuous use intention, this study can give novel point of view to understand continuous use intention of microblog. Practically, service providers could consider ways to encourage users to continually use microblog service by reinforcing social influence factors and social presence.

• Journal of the Korea Society of Computer and Information
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• v.15 no.12
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• pp.67-73
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• 2010

In SIP(Session Initiation Protocol) environment, the presence event notification operation makes presence service user to recognize presence information status changes of the other party. In conventional method, the user should send each SIP SUBSCRIBE message containing the address of the other party to the presence server. Furthermore each presence subscription requires refresh messages, and the amount of notification messages from the other party becomes large. These facts increases network traffic and the load of presence server. In this paper, to solve these problems a new presence list service has been suggested. It uses a presence list consists of URI of the other party and make it possible to subscribe by using one SUBSCRIBE message. So this method decreases the amount of SUBSCRIBE messages and refresh messages, and it also decreases the amount processing event notification messages from the subscribed the other party. And to increase the efficiency, a presence filtering method which enables to include some parts of selected presence information into the notification message body has been also suggested. The implemented system can reduce SIP message related network traffic and message processing time of the presence server. The performance of this proposed system has been evaluated by experiments, and the results showed decreasing of server processing time.

• Journal of Korea Multimedia Society
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• v.20 no.9
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• pp.1509-1518
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• 2017

Although several methods have been used to assess the pain levels, few practical methods for classifying presence or absence of the pain using pattern classifiers have been suggested. The aim of this study is to design an pattern classifier that classifies the presence or absence of the pain using electrocardiogram (ECG). We measured the ECG signal from 10 subjects with the painless state and the pain state(Induced by mechanical stimulation). The 10 features of heart rate variability (HRV) were extracted from ECG - MeanRRI, SDNN, rMSSD, NN50, pNN50 in the time domain; VLF, LF, HF, Total Power, LF/HF in the frequency domain; and we used the features as input vector of the pattern classifier's artificial neural network (ANN) / support vector machine (SVM) for classifying the presence or absence of the pain. The study results showed that the classifiers using ANN / SVM could classify the presence or absence of the pain with accuracies of 81.58% / 81.84%. The proposed classifiers can be applied to the objective assessment of pain level.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2397-2399
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• 2004

This paper deals with the messages scheduling of a CAN (Controller Area Network), based on the distributed control scheme to integrate actuators and sensors in a humanoid robot. In order to supply the distributed processing for a humanoid robot, each control unit should have the efficient control method, fast calculation and valid data exchange. The preliminary study has concluded that the performance of CAN is better and easier to implement than other network such as FIP (Factory Instrumentation Protocol), VAN (Vehicle Area Network), etc. Since humanoid robot has to treat the significant control signals from many actuators and sensors, the communication time limitation could be critical according to the transmission speed and data length of CAN specification. In this paper, the CAN message scheduling in humanoid robot was suggested under the presence of Jitter in the message group, the existence of high load of messages over the network and the presence of transmission errors. In addition, the response time under the worst case is compared with the simulation by using the simulation algorithm. As a result, the suggested messages scheduling can guarantee our CAN limitation, and utilized to generate the walking patterns for the humanoid.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.8
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• pp.3789-3808
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• 2017

This paper studies a multi-antenna wireless relay network in the presence of a jammer. In this network, the source node transmits signals to the destination node through a multi-antenna relay node which adopts the amplify-and-forward scheme, and the jammer attempts to inject additive signals on all antennas of the relay node. With the linear beamforming scheme at the relay node, this network can be modeled as an equivalent Gaussian arbitrarily varying channel (GAVC). Based on this observation, we deduce the mathematical closed-forms of the capacities for two special cases and the suboptimal achievable rate for the general case, respectively. To reduce complexity, we further propose an optimal structure of the beamforming matrix. In addition, we present a second order cone programming (SOCP)-based algorithm to efficiently compute the optimal beamforming matrix so as to maximize the transmission rate between the source and the destination when the perfect channel state information (CSI) is available. Our numerical simulations show significant improvements of our propose scheme over other baseline ones.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11B
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• pp.998-1004
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• 2008

Nowadays, in network business and communication, structures and systems are independently constructed with existing IT services and 3G services without considering common functions between them. In order to solve these problems, the study on the structure and interface of the SDP can efficiently provide the methodology of existing or new services to users and easily develop to service providers. In this paper, we will suggest an adequate structure of the SDP, and then present the implementation of a presence service enabler that is one of basic components in the SDP.

• The Journal of Korea Robotics Society
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• v.3 no.1
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• pp.68-72
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• 2008

Combining robot and network gives us many advantages like lightweight hardware specification of robot, a various robot service, simple upgrade of robot, easy management and so on. Among these advantages, Presence service and openAPI are most important. Presence is simple but powerful service. It makes user to know the status information of robot and enables user to control robot from a remote place. OpenAPI which is also a feature of WEB2.0 enables $3^{rd}$ parties to make a various mashup service easily and rapidly. Finally presence and openAPI can help URC service to be ubiquitous and successful.

• The Journal of Society for e-Business Studies
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• v.18 no.1
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• pp.191-211
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• 2013

The deployment of social network service(SNS) makes the social network game(SNG) as the new value added service of SNS be popular. But, a few study had identified the reason of this popularity and the elements of SNG. Based on the social presence theory and media richness theory, we had tried to identify three community artifacts (i.e. persistent labeling, self presentation and deep profiling) and two media characteristics(i.e. vividness and interactivity) as the SNG elements in this research. Then we had empirically validated the effect of these elements on the SNGexperience (i.e. social presence, perceived enjoyment) and behavioral intentions (i.e. Continuous usage intention, willingness to pay and loyalty) of the users. We conducted a survey to the actual SNG users. 243 data were collected and analyzed by PLS algorism. The results indicated that the community artifacts mediated by the social presence and media characteristics could significantly affect on the experiences and behavioral intentions. These findings could contribute to identify what element could be the reason of social network game popularity and could also contribute to design more attractive social network game in practice.

• Bulletin of the Korean Chemical Society
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• v.25 no.4
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• pp.539-544
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• 2004

The ability of protoberberine alkaloids, berberine and berberrubine, to act as topoisomerase II poisons is linked to the anti-cancer activity. Minor alterations in structure have a significant effect on their relative activity. Berberine, which has methoxy group at the 19-position, is significantly less potent than berberrubine. Several observations support non-specific binding to HP14 by the berberine: (i) nonspecific upfield changes in $^1H$ chemical shift for protons of the berberine; (ii) the broadening of imino protons of HP14 upon binding of the berberine; (iii) very small increases in duplex melting temperature in the presence of the berberine. Our results reveal that substitution of a hydroxyl group to a methoxy group on the 19-position, thereby converting the berberrubine to the berberine is associated with a non-specific DNA binding affinity and a reduced topoisomerase II poisoning. The presence of a bulky 19-methoxy substituent decreases intercalating properties of berberine and makes it inactive as topoisomerase II poison.

• Journal of Communications and Networks
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• v.17 no.4
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• pp.440-448
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• 2015

In this paper, we study the problem of selfish behavior of secondary users (SUs) based on cognitive radio (CR) with the presence of primary users (PUs). SUs are assumed to contend on a channel using the carrier sense multiple access with collision avoidance (CSMA/CA) and PUs do not consider transmission of SUs, where CSMA/CA protocols rely on the random deference of packets. SUs are vulnerable to selfish attacks by which selfish users could pick short random deference to obtain a larger share of the available bandwidth at the expense of other SUs. In this paper, game theory is used to study the systematic cheating of SUs in the presence of PUs in multichannel CR networks. We study two cases: A single cheater and multiple cheaters acting without any restraint. We identify the Pareto-optimal point of operation of a network with multiple cheaters and also derive the Nash equilibrium of the network. We use cooperative game theory to drive the Pareto optimality of selfish SUs without interfering with the activity of PUs. We show the influence of the activity of PUs in the equilibrium of the whole network.