• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.1-8
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• 2009

Cooperative diversity is a novel technique to improve diversity gains, capacity gains, and energy saving. This technique involves multiple terminals sharing resources in order to build a virtual antenna array in a distributed fashion. In this paper, we propose a multi-user cooperative diversity protocol called Relay-assisted Multiple Access Channel(R-MAC) that allows multiple source terminals to transmit their signals simultaneously and the relay terminal forwards the aggregated signal received from the source terminals to the destination terminal. The proposed protocol converts the distributed antenna channels into an effective MIMO channel by exploiting a relay, increasing both diversity gain and system throughput. We investigate the performance of the proposed protocol in terms of outage probability and diversity-multiplexing tradeoff where we assume block fading channel environment. Our simulation results show that the proposed protocol outperforms direct transmission in the high spectral efficiency regime where the conventional cooperative diversity protocols cannot outperform direct transmission.

• Journal of the Korean Home Economics Association
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• v.41 no.1
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• pp.111-124
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• 2003

This study tries to analyse the relationship between sexual attitudes and behaviors on the one hand and parent-child relationships on the other among college students in Korea. 1,237 students from different areas were surveyed. Sexual attitudes are subdivided into four aspects, namely, permissiveness, instrumentality, emotional exchange, and responsibility, and sexual behaviors into indirect and direct ones. Results are as follow. First, sexual attitudes and behaviors among the subjects are found being different, depending on such variables as sex, religion and dating experiences. Secondly, while being related with both indirect and direct sexual behaviors, the variable of co-residence with parents is significantly related with the aspect of permissiveness, but not with the other three aspects. Thirdly, the parent-child communication is significantly related with sexual attitudes. One who has an open pattern of communication with parents tends to have more desirable sexual attitudes and is better able to control sexual behaviors.

• Journal of Communications and Networks
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• v.14 no.5
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• pp.540-545
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• 2012

In this paper, the lagged cross-correlation of two probability density functions constructed by kernel density estimation is proposed, and by maximizing the proposed function, adaptive filtering algorithms for supervised and unsupervised training are also introduced. From the results of simulation for blind equalization applications in multipath channels with impulsive and slowly varying direct current (DC) bias noise, it is observed that Gaussian kernel of the proposed algorithm cuts out the large errors due to impulsive noise, and the output affected by the DC bias noise can be effectively controlled by the lag ${\tau}$ intrinsically embedded in the proposed function.

• Communications of the Korean Mathematical Society
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• v.37 no.1
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• pp.45-56
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• 2022

In this paper, we introduce and study the class of rings in which every ideal consisting entirely of zero divisors is a d-ideal, considered as a generalization of strongly duo rings. Some results including the characterization of AA-rings are given in the first section. Further, we examine the stability of these rings in localization and study the possible transfer to direct product and trivial ring extension. In addition, we define the class of d_E-ideals which allows us to characterize von Neumann regular rings.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11A
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• pp.1073-1080
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• 2005

In spite of many advantages of Meteor Burst Communications(MBC) on its transmission channel, the fact that its duty rate is less than 10 percents is a considerable deficiency of MBC. To overcome with this deficiency without paying large cost, we use a direct sequence(DS) simple reception system. This method doesn't need to add the components for acquisition or tracking the signal so that it keeps the cost efficiency of the MBC. But it has a disadvantage that its duty rate shows a large decline by noise. For this problem, we adopt the proposed system applying a positive feedback circuit. The improvement by this method is more significant when the received signal is weak. Simulation results show as tl is l00ms, then the burst length would be increased by $35\%$ when the initial value of the received signal power increases by 3 dB, t2 is 135ms. If the power increases by 6dB the burst length would be 170ms thus increased by $70\%$, which shows a great enhancement. Suppose now that tl is 50ms and the power is increased by 3dB, then t2 would be increased by $70\%$ to 85ms, and increasing the power by 6dB it would be increased by $130\%$ to 115ms.

• (The) Research of the performance art and culture
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• no.22
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• pp.63-92
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• 2011

This paper intends to clarify the characteristics of Seoul Ginoguigut in ritual form. This paper points out three characteristics; materialization of the journey to the world of the dead, direct communications with the dead, inclusive blessings for the dead and the living. Firstly, the journey to the world of the dead is materialized through various ritual processes of Seoul Ginoguigut. This characteristic is prominent in the context of comparisons with the death rituals of Confucianism and Buddhism, and of shamanism in other regions of Korea. Secondly, in Seoul Ginoguigut the communications of the dead and the living are made through direct dialogues between them through shaman's possession. The communications by direct dialogues between the dead and the living make it easy to accept death as a real fact, and have an effect of recognizing the individuality and uniqueness of each death. Thirdly, the blessings of Seoul Ginoguigut are so inclusive that they cover the dead's safe journey toward the world of the dead as well as the happiness of the living. This characteristic is related to the understanding of death of Korean shamanism that does not separate death and living. These three characteristics are perceived in the context of comparisons with the death rituals of Confucianism and Buddhism, and of Seoul Ginoguigut. And they give a clue to understand how the death rituals of Korean shamanism have persisted in Korean society.

• Journal of Communications and Networks
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• v.5 no.4
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• pp.374-385
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• 2003

The growing interest towards ultra-wideband (UWB) communications stems from its unique features such as baseband operation, ample multipath diversity, and the potential of enhanced user capacity. But since UWB has to overlay existing narrowband systems, multiple access has to be achieved in the presence of narrowband interference (NBI). However, existing baseband spreading codes for UWB multiple access are not flexible in handling NBI. In this paper, we introduce two novel spreading codes that not only enable baseband UWB multiple access, but also facilitate flexible NBI cancellation. We construct our codes using a single carrier or multiple carriers (SC or MC), which can be implemented with standard discrete-cosine transform (DCT) circuits. With our SC/MC codes, NBI can be avoided by simply nulling undesired digital carriers. Being digital, these SC/MC codes give rise to multiband UWB systems, without invoking analog carriers. In addition, our SC/MC codes enable full multipath diversity, and maximum coding gains. Equally attractive is their capability to reduce the number of interfering users, with simple matched filter operations. Comprehensive simulations are also carried out to corroborate our analysis.

• 한국경영정보학회:학술대회논문집
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• 2007.06a
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• pp.488-493
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• 2007

The main goal of this study is to propose a model of simplicity and interactivity effect on usability in the blog services. As web-based applications become increasingly complicated, the need for simplicity in user interface design has grown for better usability. Also, interactivity has been known to influence on usability. Previous studies argued that usability is a key factor for system success. Usability is concerned with attributes of an application that makes it understandable, learnable, easy to use, and attractive. For the complicated technology, perceived control, related to direct manipulation of an object, is important. In this regard, we posit that simplicity, interactivity, and perceived control makes important antecedents to usability. Finally, we tested that the effect of usability on user s loyalty with the blog services along with trust and satisfaction. Future studies will empirically examine the proposed model, emphasizing the importance of simplicity and interactivity for the user interface design.

• Journal of Korea Multimedia Society
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• v.20 no.12
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• pp.1849-1855
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• 2017

The main purpose of cooperative communications is improvement of communication quality and efficient use of transmission power. In this paper, a cooperative retransmission method is proposed, where neighbor nodes that receive messages correctly between transmit and receive nodes will participate in retransmission of the erroneous packet of the direct link. When the proposed retransmission method is used, the performance of the PER can be greatly improved. In case that the limited information is included in the NACK message, the transmit power of the retransmission packet can be reduced using the proper power control method.

• Journal of Communications and Networks
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• v.5 no.2
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• pp.124-134
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• 2003

In this paper, we investigate the error probability performance of noncoherently detected orthogonal modulation combined with Alamouti space-time block coding. We find that there are two types of pair-wise error probabilities that characterize the performance. We employ methods that allow a direct evaluation of exact, closed-form expressions for these error probabilities. Theoretical as well as numerical results show that noncoherent orthogonal modulation combined with space-time block coding (STBC) achieves full spatial diversity. We derive an expression for approximate average bit error probability for-ary orthogonal signaling that allows one to show the tradeoff between increased rate and performance degradation.