• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권12호
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• pp.3061-3080
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• 2012

To improve the sensing performance, cooperation among secondary users can be utilized to collect space diversity. In this paper, we focus on the optimization of cooperative spectrum sensing in which multiple cognitive users efficiently cooperate to achieve superior detection accuracy with minimum sensing error probability in multiple cross-over cognitive radio networks. The analysis focuses on two fusion strategies: soft information fusion and hard information fusion. Under soft information fusion, the optimal threshold of the energy detector is derived in both noncooperative single-user and cooperative multiuser sensing scenarios. Under hard information fusion, the optimal randomized rule and the optimal decision threshold are derived according to the rule of minimum sensing error (MSE). MSE rule shows better performance on improving the final false alarm and detection probability simultaneously. By simulations, our proposed strategy optimizes the sensing performance for each cognitive user which is randomly distributed in the multiple cross-over cognitive radio networks.

• 한국초등수학교육학회지
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• 제16권3호
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• pp.321-336
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• 2012

인식 주체는 자신의 경험을 바탕으로 주어진 대상에 구조를 부여하여 대상을 구조로 인식하려고 한다. 주어진 문제 맥락 속에서 주체가 대상에 부여할 수 있는 구조는 횡적, 종적으로 다양하다. 구조의 횡적 다양성의 측면에서, 한 대상 속에서 다양한 구조를 발견하는 데 초점을 맞춘 문제해결 활동은 다양한 전략 사용에 중점을 둔 문제해결 교육의 보완이 될 수 있다 또, 도형 패턴 과제에서 일반식의 발견은 문제해결의 종착점이 아닌 새로운 구조 탐구의 시발점으로 여겨져야 한다. 구조의 종적 다양성의 측면에서, 교사는 학생이 보는 구조와 교사가 보는 구조가 다를 가능성에 유의하면서, 구조의 종적 다양성에 기초하여 아동이 진보의 경험을 할 수 있도록 지도하는 방안을 모색할 필요가 있다.

• 한국임상보건과학회지
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• 제8권2호
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• pp.1426-1435
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• 2020

Objective: This study aims to develop CFT, a screening test for dementia that can be conducted on patients with mild cognitive impairment or early dementia. Methods: This study was conducted on therapists working at occupational therapy hospital in Gyeongsangnam-do. The data collection period is two months from July to September 2020, and the research participants were briefed on the purpose, significance, and anonymity of the research in consideration of ethical issues. A total of 33 copies of the data were finally analyzed, excluding those containing insufficient answers and errors, by distributing 40 copies of the data. SPSS Data Access pack 8.0 was used for data analysis, Cronbach's α value was evaluated for internal consistency reliability of each item, and Pearson Correlation coeffient between the lower scales of the assessment tool was measured. Results: The Cronbach's α value of the CFT was shown as .892 and the reliability of the assessment paper was shown to be quite high. The Cronbach's α value for each item in the cognitive assessment tool was the highest at .899 in the subtraction item, with exercise control (mook Chi Pa) at 888, visual memory, plus .887. The correlation of each item of cognitive assessment tools was found to be most correlated with the number of sustained concentrates and word2 to .934; in the stop word-numeric item and visual memory to be .85; and in the addition to the auditory memory item .739. Conclusion: Therefore, this study developed cognitive evaluation tools that can distinguish the diversity and cognitive level of screening tests and clarify standards, which are different from the existing dementia screening tools in Korea. Furthermore, the cognitive assessment tools of this study can be verified by applying them to patients with mild cognitive impairment and early dementia, and the criteria for generalization can be established.

• 한국통신학회논문지
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• 제38A권3호
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• pp.249-257
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• 2013

최근 고속 데이터 서비스의 보급으로 데이터 사용량이 급증함에 따라 이를 수용하기 위한 주파수 자원의 효율적 사용 방법에 대한 연구가 주목받고 있다. 따라서 주파수 효율성을 향상시키기 위해 주파수 사용에 대한 우선권을 가진 사용자와 후순위에 있는 사용자가 해당 주파수 대역을 공유하는 기술인 인지 무선 기술(Cognitive Radio, CR)이 제안되었다. 본 논문에서는 CR 시스템에서 직교하는 채널 벡터를 이용하여 선순위 시스템에게 미치는 간섭을 줄이면서 후순위 시스템의 성능 향상을 동시에 고려한 사용자 선택 기법을 제안한다. 모의실험 결과 제안 기법을 적용했을 때 전체 시스템의 합 용량이 기존 기법보다 약 1.62bps/Hz의 이득을 가지는 것을 확인하였다.

• Journal of Communications and Networks
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• 제18권3호
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• pp.288-298
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• 2016

Proactive relay selection in cognitive radio networks has recently received considerable attention. However, its outage probability analysis is limited to partially-identical fading distributions, uncorrelation among received signal-to-noise ratios (SNRs), and no direct channel. This paper completes this literature deficiency by generalizing the existing analysis for non-identical fading distributions, correlation among received SNRs, and with direct channel. Numerous results demonstrate that relay selection with a direct channel achieves a higher diversity order and superior performance than that without a direct channel at virtually no cost of power and bandwidth. Further, proactive relay selection suffers an error floor at either a large maximum transmit power or large maximum interference power; however, the error floor level can be significantly remedied with an increase in the number of relays.

• ETRI Journal
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• 제34권2호
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• pp.272-275
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• 2012

This letter studies the problem of exploiting multichannel diversity in a spectrum sharing system, where the secondary user (SU) sequentially explores channel state information on the licensed channels with time consumption. To maximize the expected achievable throughput for the SU, we formulate this problem as an optimal stopping problem, whose objective is to choose the right channel to stop exploration based on the observed signal-to-noise ratio sequence. Moreover, we propose a myopic but optimal rule, called one-stage look-ahead rule, to solve the stopping problem.

• Journal of Communications and Networks
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• 제13권5호
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• pp.456-462
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• 2011

This paper investigates the outage behavior of peak interference power limited cognitive radio (CR) networks with multiple transmit antennas. In CR-multi-input single-output (MISO) channel, the total transmit power is distributed over the transmitantennas. First, we use the orthogonal space-time codes (STC) to achieve the transmit diversity at CR-receiver (rx) and investigate the effect of the power distribution on the interference power received at the primary-receiver (P-rx). Then, we investigate the transmit antenna selection (TAS) scheme in which the CR system selects the best transmit antenna and allocates all the power to the selected best antenna. Two transmit antenna selection strategies are proposed depending on if feedback channel is available or not. We derive the closed form expressions of outage probability and outage capacity of all schemes with arbitrary number of transmit-antennas. We show that the proposed schemes significantly improve the outage capacity over the single antenna systems in Rayleigh fading environment. We also show that TAS based scheme outperforms the STC based scheme when peak interference power constraint is imposed on the P-rx only if a feedback channel from CR-rx to CR-transmitter is available.

• 한국콘텐츠학회논문지
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• 제14권8호
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• pp.505-516
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• 2014

본 연구는 국제영재교육에서 창의사고필터링모형(Creative Thinking Filtering Model : CTFM)교육프로그램 적용이 창의성의 인지적 영역(유창성, 융통성, 독창성)과 정의적 영역(독자성, 호기심, 다양성, 민감성, 유모감각, 개별성)에 어떠한 영향을 미치는 지를 규명하는데 있다. 자료처리를 위한 통계방법으로 공분산분석 (Analysis of Covariance : ANCOVA)를 실시하였으며, 그 결과는 다음과 같다. 첫째, CTFM을 적용한 집단이 통제집단보다 인지적 영역과 정의적 영역이 높은 것으로 나타났다. 구체적으로 인지적 영역에서는 유창성, 융통성, 독창성 3요인 모두에서, 정의적 영역에서는 민감성을 제외한 독자성, 호기심, 개별성, 다양성, 민감성, 유모감각의 5요인에서 CTFM을 적용한 학생들이 높은 것으로 나타났다. 둘째, CTFM을 적용하기 전과 적용한 후에 인지적 영역의 창의성을 분석한 결과, 인지적 영역의 3요인인 유창성, 융통성, 독창성 모두 향상되었으며, 특히 유창성이 가장 많이 향상된 것으로 나타났다. 셋째, CTFM을 적용하기 전과 적용한 후에 정의적 영역의 창의성을 분석한 결과, 정의적 영역의 6요인 중 독자성, 다양성, 유모감각, 개별성의 4요인이 향상되었으며, 특히 독자성이 가장 많이 향상된 것으로 나타났다.

• Human Ecology Research
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• 제52권2호
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• pp.111-125
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• 2014

The purpose of this study was to examine how an undergraduate family diversity course supported students to enhance undergraduate students' understanding of diversity issues and cultural competence that are necessary to work with diverse families and children as future family science professionals. We collected qualitative research data from 108 students who were enrolled in five sections of an undergraduate-level diversity course, Working with Diverse Families and Children , using nine open-ended questions. In the current study, we specifically focused on four questions in relevant to what undergraduate students learned and what they desired to learn more about diversity issues in families grounded in Hollinger's developmental model of ethical reflection. Using inductive and deductive iterative processes and triangulation, we conducted thematic analysis. Overall, our findings showed that undergraduate students understood the core concepts of diversity and cultural competence. However, they understood these issues at different stages of Hollinger's model of ethical reflection after taking the course. Most undergraduate students accomplished their cognitive and empathetic understanding of diversity and were primarily in Stages 1 and 2. We suggest interactive and reflective teaching strategies that may be effective for undergraduate students to challenge their own biases, practice ethical decision, and prepare for social actions as family science professionals.

• 한국인터넷방송통신학회논문지
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• 제10권5호
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• pp.39-44
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• 2010

본 논문에서는 최근에 많은 주목을 받고있는 상황인지 시스템을 협동릴레이 시스템에 적용하였을 때 상황인지 협동 릴레이 시스템의 성능을 유도하였다. 협동 릴레이 시스템은 기회전송 릴레이를 채택하였을 때와 채택하지 않았을 때의 성능을 비교하였다. 특히 목적지에서 시스템 구현의 간편성 때문에 많이 채택하고 있는 선택 결합방식을 고려하였는데, 이 경우 필수적으로 발생되는 채널 상태 정보(CSI)를 주고받으면서 발생되는 지연의 영향을 고려하였다. 분석결과 기회전송 릴레이를 채택할 경우 기회전송 릴레이를 채택하지 않은 경우보다 주어진 조건에서 최대 0.6 dB 열화 되었으며, 시스템의 성능은 상황인지 릴레이의 주파수 획득 확률보다는 채널 상태정보의 지연에 더욱 민감한 영향을 받음을 알 수 있었다.