• Journal of Communications and Networks
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• v.18 no.3
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• pp.375-386
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• 2016

Most existing studies on broadcast services in orthogonal frequency division multiplexing (OFDM) systems have focused on how to allocate the transmission power to the subcarriers. However, because a broadcasting system must guarantee quality of service to all users, the performance of the broadcast service dominantly depends on the channel state of the user who has the lowest received signal-to-noise ratio among users. To reduce the effect of the worst user on the system performance, we propose a joint delivery scheme of unicast and broadcast transmissions in OFDM systems with broadcast and unicast best-effort users. In the proposed joint delivery scheme, the BS delivers the broadcast information using both the broadcast and unicast subcarriers at the same time in order to improve the performance of the broadcast service. The object of the proposed scheme is to minimize the outage probability of the broadcast service while maximizing the sum-rate of best-effort users. For the proposed joint delivery scheme, we develop an adaptive power and subcarrier allocation algorithm under the constraint of total transmission power. This paper shows that the optimal power allocation over each subcarrier in the proposed scheme has a multi-level water filling form. Because the power allocation and the subcarrier assignment problems should be jointly solved, we develop an iterative algorithm to find the optimal solution. Numerical results show that the proposed joint delivery scheme with adaptive power and subcarrier allocation outperforms the conventional scheme in terms of the outage probability of the broadcast service and the sum-rate of best-effort users.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1639-1644
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• 2016

In this paper, we consider the performance improvement that can be obtained with interference alignment (IA) technique applied to 802.11ac based multi-BSS WiFi service. To this end, we developed a system simulator consisting of a link-level PHY simulator, based on 802.11ac specification, and multi-BSS proportional-fair scheduler. Specifically, assuming perfect channel side information and synchronization of signals from multiple APs, we used a SLNR based interference alignment algorithm proposed in [13] and compared its performance with that of multiuser beamforming based time-sharing system. The performance was evaluated in terms of average throughput per BSS and 5% worst user throughput. The results show that 70 to 100% throughput gain can be obtained in this ideal scenario.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.333-338
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• 2006

최근 사용자에 대한 많은 정보를 얻는 것이 가능해지면서, 데이터마이닝 기법이나 Contents 추천 기법을 이용한 맞춤형 서비스가 가능하게 되었다. 특히, 대부분의 사람들에게 TV 프로그램 시청은 여가생활시간에서 가장 높은 비중을 차지 하고 있다. 따라서, 보다 지능적인 TV 프로그램 서비스를 제공하는 기술에 대하여 관심이 고조되고 있다. 본 논문에서는 TV-Anytime을 이용하여 개인화된 Electronic Program Guide (EPG)를 생성하고, 개인화된 EPG 정보를 활용하여 시청자에게 맞춤형 TV 프로그램 서비스를 제공하는 시스템에 대한 연구 결과를 제시한다. 또한 시청자의 시청패턴과 TV 프로그램 선호도를 바탕으로 시청자가 원하는 프로그램을 추천하는 TV Program Recommender Agent와 방송 및 TV 프로그램에 대한 대화를 담당하는 TV Program Helper Agent, 시스템 조정 및 메시지 전달을 담당하는 Coordinator Agent로 이루어진 멀티에이전트 기반 시스템 구조를 제시한다.

• Journal of Korean society of Dental Hygiene
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• v.13 no.2
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• pp.211-220
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• 2013

Objectives : This study intended to figure out illegal treatment by unlicensed person in dental area and factors, which were considered as user's position on the basis of the local community investigation of health conditions in chungbuk provinces in 2008. Methods : This study used chi-square test and complex sample design of multi-variate logistic regression analysis to question 12,443 peoples who have experience on illegal dental treatment. Results : Multi-variate logistic regression analysis results showed that factors having related to illegal dental treatment are sex, age, education standards, subjective awareness of oral health condition, drinking experience of lifetime, unmet need of dental treatment, chewing difficulty, use of dentures, experience of scaling and the use of interdental care instrument. Conclusions : As a result of this study, in order to root out illegal dental treatment, we need to expand the breadth of health insurance coverage so that it can reduce the burden of dental expenses. Moreover, we need to set out health service of public oral health to inform the importances of maintaining good oral health and the problems of illegal dental treatment by unlicensed person.

• Asia pacific journal of information systems
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• v.15 no.2
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• pp.195-218
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• 2005

The emergence of ubiquitous computing environment will change the service architecture of business information systems such as Decision Support System(DSS), which will be a new application. Recent mobile DSSs allow the decision makers to be benefited from web and mobile technology. However, they seldom refer to context data, which are useful for proactive decision support. Meanwhile, ubiquitous applications so far provide restricted personalization service using context and preference of the user, that is, they do not fully make use of decision making capabilities. Hence, this paper aims to describe how the decision making capability and context-aware computing are jointly used to establish ubiquitous applications. To do so, an amended DSS paradigm: CKDDM(Context-Knowledge-Dialogue-Data-Model) is proposed in this paper. What will be considered for the future decision support systems when we regard ubiquitous computing technology as an inevitable impact that enforces the change of the way of making decisions are described. Under the CKDDM paradigm, a framework of ubiquitous decision support systems(ubiDSS) is addressed with the description of the subsystems within. To show the feasibility of ubiDSS, a prototype system, CAMA-myOpt(Context-Aware Multi Agent System-My Optimization) has been implemented as an illustrative example system.

• Journal of Advanced Navigation Technology
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• v.7 no.1
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• pp.59-71
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• 2003

The channel scheduler is suggested the radio resource management method in order to provide service with guaranteeing fairness and throughput to the users who use limited wireless channel. Proportional fairness scheduling algorithm is the channel scheduler used in the AMC(Adaptive Modulation and Coding)/TDM system, and this algorithm increases the throughput considering the user's time fairness. In this paper is suggested the channel scheduler combining CDM scheme available in AMC/TDM/CDM system. Unlike the system which only uses TDM which provide the only one user at the same slot, this scheduler can service a lot of users since this uses the CDM scheme with multi-cord channel. At every moment, allocation of transmission power to multi-channel users is problematic because of CDM scheme. In this paper, we propose a water-filling scheduling algorithm to solve the problem. Water-filling fairness(WF2) scheduling algorithm watches the average channel environment. So, this modified method guarantees fairness for each user in terms of power and service time.

• The Journal of the Acoustical Society of Korea
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• v.40 no.5
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• pp.523-529
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• 2021

In this paper, we designed and developed an Emotional Speech Synthesis Markup Language (SSML) processor. Multi-speaker emotional speech synthesis technology that can express multiple voice colors and emotional expressions have been developed, and we designed Emotional SSML by extending SSML for multiple voice colors and emotional expressions. The Emotional SSML processor has a graphic user interface and consists of following four components. First, a multi-speaker emotional text editor that can easily mark specific voice colors and emotions on desired positions. Second, an Emotional SSML document generator that creates an Emotional SSML document automatically from the result of the multi-speaker emotional text editor. Third, an Emotional SSML parser that parses the Emotional SSML document. Last, a sequencer to control a multi-speaker and emotional Text-to-Speech (TTS) engine based on the result of the Emotional SSML parser. Based on SSML which is a programming language and platform independent open standard, the Emotional SSML processor can easily integrate with various speech synthesis engines and facilitates the development of multi-speaker emotional text-to-speech applications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.9
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• pp.2056-2063
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• 2015

Recently, as the service scale of cloud service is expanded, an anxiety due to concerns on new vulnerabilities and security related incidents and accidents are also increasing. This paper proposes a certification scheme for multiple session management of security sessions which are generated after the user authentication. The proposed session multiplexing scheme enables the independent management of security sessions in the level of virtualization (hypervisor) within the service provider. As a result of performance analysis, providing a strong safety due to session multiplexing and mutual authentication, and the superiority of performance was proven by comparing it with the existing mutual authentication encryption algorithms.

• Journal of KIISE
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• v.42 no.9
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• pp.1175-1184
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• 2015

Recently, there has been an explosive increase in the volume of multimedia data that is available as a result of the development of multimedia technologies. More and more data is becoming available on a variety of web sites, and it has become increasingly cost prohibitive to have a single data server store and process multimedia files locally. Therefore, many service providers have been likely to outsource data to cloud storage to reduce costs. Such behavior raises one serious concern: how can data users be authenticated in a secure and efficient way? The most widely used password-based authentication methods suffer from numerous disadvantages in terms of security. Multi-factor authentication protocols based on a variety of communication channels, such as SMS, biometric, or hardware tokens, may improve security but inevitably reduce usability. To this end, we present a data block-based authentication scheme that is secure and guarantees usability in such a manner where users do nothing more than enter a password. In addition, the proposed scheme can be effectively used to revoke user rights. To the best of our knowledge, our scheme is the first data block-based authentication scheme for outsourced data that is proven to be secure without degradation in usability. An experiment was conducted using the Amazon EC2 cloud service, and the results show that the proposed scheme guarantees a nearly constant time for user authentication.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.2
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• pp.242-253
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• 1994

For the implementation of a Service Node, which is proposed in the companion paper to provide multiparty conference type sevices in the ISDN, we define some technical aspects such as connection control, service control procedure and control messages in this paper. Additional connection control procedures for the multiparty connections are annexed to the CCITT Rec. Q.931 and Q.764 for the ISDN subscriber and common channel interoffice signaling. A new set of service control procedures is also established according to the necessary service control functions. The messages for these procedures are formatted using user-to-user signaling parts of Q.931 and Q.763 messages not to affect on the existing signaling system. Some technical requirements of subscriber terminal for the multiparty services are also deduced.