• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.1
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• pp.20-33
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• 2015

Spectrum sensing is a key component of cognitive radio. The prediction of the primary user status in a low signal-to-noise ratio is an important factor in spectrum sensing. However, because of noise uncertainty, secondary users have difficulty distinguishing between the primary signal and an unauthorized signal when an unauthorized user exists in a cognitive radio network. To resolve the sensitivity to the noise uncertainty problem, we propose an entropy-based spectrum sensing scheme to detect the primary signal accurately in the presence of an unauthorized signal. The proposed spectrum sensing uses the conditional entropy between the primary signal and the unauthorized signal. The ability to detect the primary signal is thus robust against noise uncertainty, which leads to superior sensing performance in a low signal-to-noise ratio. Simulation results show that the proposed spectrum sensing scheme outperforms the conventional entropy-based spectrum sensing schemes in terms of the primary user detection probability.

• Communications for Statistical Applications and Methods
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• v.16 no.5
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• pp.821-840
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• 2009

This article addresses the problem of estimating a family of general population parameter ${\theta}_{({\alpha},{\beta})}$ using auxiliary information in the presence of measurement errors. The general results are then applied to estimate the coefficient of variation $C_Y$ of the study variable Y using the knowledge of the error variance ${\sigma}^2{_U}$ associated with the study variable Y, Based on large sample approximation, the optimal conditions are obtained and the situations are identified under which the proposed class of estimators would be better than conventional estimator. Application of the main result to bivariate normal population is illustrated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.5
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• pp.349-359
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• 1986

This paper is the basic research to identify automatically signals that are less than the bandwidth of 200Hz in shortwave band between 3 to 7 MHz and rarely appear. In order to do so, first, we describe the Detection and Estimation method of testing for the presence of absence about OOK signals of odB degree in 100KHz bandwidth. In the course of Detection and Estimation, it has decided the presence of OOK modulation Signal in additive noise to about 77% using LOD and E-C and about 90% using pattern model method of correlation function.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.5
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• pp.982-984
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• 2017

In time domain, a radar signal is divided into two segments: one is for a transmitted pulse and the other is for receiving possible returns from radar targets. Also the received signal is relatively weak and consists of background noise except for the reflected signals from radar targets. In this Letter, we present an energy detection based spectrum sensing for a radar signal in the presence of noise power uncertainty exploiting this characteristics.

• Proceedings of the Korean Society for Language and Information Conference
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• 2007.11a
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• pp.275-284
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• 2007

Among the languages that allow long-distance reflexives, some languages have blocking effects, whereas others don't. The goal of this paper is to provide computational algorithms that can handle presence and absence of blocking effects of long-distance reflexives. We will examine the blocking effects in Chinese and Korea and develop computational algorithms for handling blocking effects in those two languages. The algorithms will be developed by incorporating Chierchia's Binding Theory into Steedman's Combinatory Categorial Grammar (CCG). Through the analyses and implementations, this paper illustrates how blocking effects can be implemented computationally.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3A
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• pp.257-265
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• 2004

General closed-form expression is derived and analyzed for the exact bit error rate (BER) performance of the arbitrary rectangular Gray coded QAM signal in conjunction with maximal-ratio combining (MRC) diversity on frequency non-selective slow m-distributed Nakagami fading channel in the presence of co-channel interference. Numerical results demonstrate error performance improvement with the use of MRC diversity reception. The new expressions presented here are suitable for evaluating various cases of practical interest on wireless communication channels.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.575-578
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• 2005

인터넷 사용자의 급격한 증가로 인하여 인터넷 서비스 보급이 대중화됨에 따라 인터넷을 이용한 다양한 부가 서비스들이 창출되고 있다. 이러한 흐름에 발맞추어 VoIP(Voce over IP) 표준기술들이 최근 몇 년간 주요 이슈가 되고 있다. VoIP 서비스가 시장성 있는 기술로서 각광을 받게 되면서, VoIP 서비스를 위한 시스널링 프로토콜인 SIP(Session Initiation Protocol)가 기존의 H.323을 대체하는 기술로서 주목 받고 있다. 또한 SIP를 이용한 다양한 부가 서비스들도 함께 관심이 집중되고 있으며, 그중에서도 SIP를 이용한 프레즌스 서비스에 많은 관심을 보이고 있다. 본고에서는 현재 IETF를 중심으로 진행되고 있는 SIP 기반 프레즌스 부가 서비스에 대한 표준 기술 및 주요 이슈에 대해 소개하고자 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.537-539
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• 2014

Recently, the Univeral Plug and Play (UPnP) Form has relased UPnP Cloud, which is an extension to the basic UPnP architecture that enables device to device connectivity across the Internet. UPnP Cloud uses the Extensible Messaging and Presence Protocol (XMPP) to connect devices located in different domains. In this paper, the details of the UPnP Cloud are presented. We demonstrate how UPnP Cloud enables contents to be shared remotely, and how it can be used in connection with DLNA.

• Communications for Statistical Applications and Methods
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• v.28 no.5
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• pp.493-510
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• 2021

The present article endeavours to develop partial optional randomized - response technique (PORT) to deal with sensitive issues in presence of non-response in successive sampling. Calibration techniques have been embedded with PORT to estimate sensitive population mean at current move in two move successive sampling in presence of non-response. Optimum calibration weights are computed at each move with the aid of constraints based on auxiliary information. Detailed properties of the proposed estimators have been discussed. Possible cases in which non-response may creep at two moves has been explored. The proposed technique has been compared with the modified existing technique. Simulation results indicate that the proposed technique is more efficient than existing, modified one. Suitable recommendations are forwarded.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.10
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• pp.1390-1393
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• 2020

Recently, a hologram-like system and a virtual human to provide a realistic experience has been serviced in various places such as musical performance and museum exhibition. Also, the realistically responded virtual human in the hologram-like system need to be expressed in a way that matches the users' interaction. In this paper, to improve the feeling of being in the same space with a virtual human in the hologram-like system, user's gesture based interactive contents were presented, and the effectiveness of interaction was evaluated. Our approach was found that the gesture based interaction was provided a higher sense of co-presence for immersion with the virtual human.