• 한국통신학회논문지
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• 제34권1C호
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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.

• 대한가정학회지
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• 제41권1호
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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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• 제14권5호
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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.

• 대한수학회논문집
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• 제37권1호
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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.

• 한국통신학회논문지
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• 제30권11A호
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• pp.1073-1080
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• 2005

MBC(meteor burst communications)는 그 전송로의 많은 장점에도 불구하고 도통율이 수$\%$이하로 낮다는 큰 결점이 있다. 이를 위해 큰 경제적 부담 없이 전송 채널의 도통율을 향상시키는 방법으로서 기존의 DS(Direct Sequence) 간이 수신시스템에 정귀환회로를 적용하였다. 기존의 DS 간이 수신방식은 동기신호의 포착이나 유지에 소요되는 시스템을 생략할 수가 있어서 MBC가 가지는 경제성을 만족시킬 수 있으나, 잡음의 영향을 크게 받아 도통율이 떨어지는 단점이 있다. 이를 위해 DS 간이 수신시스템에 정귀환회로를 적용하여 SNR을 6dB이상 향상 시켰다. 이 방법으로 개선되는 효과는 수신신호가 약한 환경에서 보다 더 큰 것으로 나타나는데 시뮬레이션에 의하면 SNR이 약 6dB 개선되었을 때 평균 버스트 길이가 100ms인 것은 $70\%$로 개선되어 170ms로 되고, 50ms환경에서는 $130\%$개선되어 115ms가 되어 수신신호가 약한 환경에서 도통율이 크게 개선점을 확인할 수 있었다.

• 공연문화연구
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• 제22호
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• pp.63-92
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• 2011

이 글은 서울 진오기굿의 의례형식을 중심으로 의례적 특징을 살펴보고자 하였다. 이 글은 서울 진오기굿의 의례상 특징으로 저승길의 가시적 구현, 망자와의 직접적인 의사소통, 죽은 자와 산 자를 아우르는 포괄적인 축원 등 세가지를 지적하였다. 먼저 서울 진오기굿은 굿의 의례과정을 통해 죽은 자의 저승길을 가시적으로 구현한다. 이는 유교, 불교의 죽음의례 뿐만 아니라 타 지역 무속 죽음의례와 비교했을 때도 상대적으로 두드러지는 서울 진오기 굿의 특징 가운데 하나이다. 두 번째로 서울 진오기굿에서는 무당의 신내림을 매개로 죽은 자와의 의사소통이 직접적인 대화형식으로 이뤄진다. 죽은 망자와의 직접적인 의사소통은 죽음을 현실로 받아들이고, 개개 죽음의 개별성과 특수성을 확인하는 의미를 갖는다. 세 번째로 서울 진오기굿에서 이뤄지는 축원은 죽은 자의 저승천도에 머물지 않고 살아있는 가족들의 평안까지 포괄한다. 이는 죽음이 죽은 자와 산 자에 다 관련되며, 죽음과 삶은 구분되나 분리되지 않는다는 무속의 죽음이해를 보여준다. 이 글에서 밝힌 서울 진오기굿의 의례적 특징은 유교, 불교 죽음의례와의 상대적 비교를 염두에 둔 것으로, 그것은 유교, 불교 죽음의례와의 상호관계에서 어떻게 무속 죽음의례가 한국사회에서 하나의 죽음의례로서 존재가치와 기능을 인정받아왔는가를 이해하는 단서를 제공한다.

• Journal of Communications and Networks
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• 제5권4호
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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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• 한국경영정보학회 2007년도 International Conference
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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.

• 한국멀티미디어학회논문지
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• 제20권12호
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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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• 제5권2호
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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.