• Journal of Communications and Networks
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• 제12권2호
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• pp.158-167
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• 2010

The energy efficiency of wireless infrastructure and terminals has been drawing renewed attention of late, due to their significant environmental cost. Emerging green communication paradigms such as cognitive radios, are also imposing the additional requirement of flexibility. This dual requirement of energy efficiency and flexibility poses new design challenges for implementing radio functional blocks. This paper focuses on the area vs. power trade-offs for the type of channel filters that are required in the digital frontend of a flexible, energy-efficient radio. In traditional CMOS circuits, increased area was traded for reduced dynamic power consumption. With leakage power emerging as the dominant mode of power consumption in nanoscale CMOS, these trade-offs must be revisited due to the strong correlation between area and leakage power. The current work discusses how the increased timing slacks obtained by increasing the parallelism can be exploited for overall power reduction even in nanoscale circuits. In this context the paper introduces the notion of 'area efficiency' and a metric for evaluating it. The proposed metric has also been used to compare the area efficiencies of different classes of time-shared filters.

• 인지과학
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• 제11권3_4호
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• pp.73-81
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• 2000

이 연구는 지식유형에 따른 표상 차이를 확인하기 위해서 범주지식과 각본지식의 위계성과 전형성에 대한 점화효과를 측정하였다. 실험 1에서는 상위개념을 점화단어로 제시하고 하위개념을 목표단어로 제시한 다움 목표단어의 어휘판단시간을 측정하였다. 그 결과, 범주지식은 전형단어가 비전형단어보다 반응시간이 빨랐지만, 각본지식은 두 조건간의 차이가 없었다. 실험 2에서는 하위개념을 점화단어로 제시하고 상위개념을 목표단어로 제시한 다음 목표단어의 어위판단시간을 측정하였다. 범주지식이 각본지식보다 반응시간이 빨랐으며, 두 지식 모두 전형성 효과는 관찰되지 않았다. 이러한 결과는 범주지식은 전형성에 따른 위계구조를 구성하지만 각본지식은 범주지식에 비해서 위계성과 전형성이 약회된 구조로 표상될 가능성을 시사하는 것이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권7호
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• pp.3414-3434
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• 2016

Classical key generation is complicated to update and key distribution generally requires fixed infrastructures. In order to eliminate these restrictions researchers have focused much attention on physical-layer (PHY-layer) based key generation methods. In this paper, we present a PHY-layer fingerprints based fuzzy key generation scheme, which works to prevent primary user emulation (PUE) attacks and spectrum sensing data falsification (SSDF) attacks, with multi-node collaborative defense strategies. We also propose two algorithms, the EA algorithm and the TA algorithm, to defend against eavesdropping attacks and tampering attacks in mobile cognitive radio networks (CRNs). We give security analyses of these algorithms in both the spatial and temporal domains, and prove the upper bound of the entropy loss in theory. We present a simulation result based on a MIMO-OFDM communication system which shows that the channel response characteristics received by legitimates tend to be consistent and phase characteristics are much more robust for key generation in mobile CRNs. In addition, NIST statistical tests show that the generated key in our proposed approach is secure and reliable.

• 패션비즈니스
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• 제14권5호
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• pp.49-65
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• 2010

The purpose of this paper is to derive the categories of negative e-WOM (electronic word of mouth) via consumer review. Disclosing the details of negative e-WOM based consumer reviews has never been done before. For this reason, a content analysis was adopted to provide knowledge and understanding of the phenomenon. This paper analyzes the content of 630 consumer reviews posted on the open market internet site, www.auction.co.kr. The analysis was conducted from October 20th, 2008 to March 10th, 2009. The results indicated that the negative e-WOM based consumer reviews can be divided into two categories: the cognitive evaluation and the expression of consumer's emotion. The category of cognitive evaluation is consisted of negative e-WOM of product, negative e-WOM of service, and warning about the risk of purchasing products. The category of expressing consumers' emotion are composed of venting customers' dissatisfaction and passive response of dissatisfaction. Investigating the details of negative e-WOM has a number of implications. Most importantly, the results revealed multidimensional structure of negative e-WOM. This understanding of negative e-WOM communication allows marketers to improve products and services that better meet customers' current and future needs.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권4호
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• pp.1192-1207
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• 2014

Dynamic spectrum sharing is a key technology to improve spectrum utilization in wireless networks. The elastic spectrum management provides a new opportunity for licensed primary users and unlicensed secondary users to efficiently utilize the scarce wireless resource. In this paper, we present a game-theoretic framework for dynamic spectrum allocation where the primary users rent the unutilized spectrum to the secondary users for a monetary profit. In reality, due to the ON-OFF behavior of the primary user, the quantity of spectrum that can be opportunistically shared by the secondary users is limited. We model this situation with the renewal theory and formulate the spectrum pricing scheme with the Bertrand game, taking into account the scarcity of the spectrum. By the Nash-equilibrium pricing scheme, each player in the game continually converges to a strategy that maximizes its own profit. We also investigate the impact of several properties, including channel quality and spectrum substitutability. Based on the equilibrium analysis, we finally propose a decentralized algorithm that leads the primary users to the Nash-equilibrium, called DST. The stability of the proposed algorithm in terms of convergence to the Nash equilibrium is also studied.

• 복식
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• 제65권5호
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• pp.74-87
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• 2015

It is common for popular products to sell out, and be out of stock. The purpose of this study is to examine the responses of consumers who have experiences of shopping online, and finding their desired products unavailable from being sold out. In order to carry out the study, in-depth interviews were conducted with ten recruits who were recruited from the Internet community, Soul Dresser, which is part of the Korean web portal, Daum. First, the cognitive reaction of the interviewees showed both positive and negative responses when they found out that their desired product was sold out. However, in the case of emotional reaction, all of them showed negative reactions. Observations showed that consumers researched and found similar products including price when they realized that their desired products were not going to be re-stocked. And in cases of similar products not being available, the consumers looked to buy other types of products such as bags, shoes, and other accessories.

• 지역사회간호학회지
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• 제29권2호
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• pp.206-219
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• 2018

Purpose: This study tries to identify and clarify the concept of fear of dementia. Methods: The hybrid model method was used to perform a conceptual analysis of fear for dementia. Results from both the theoretical review of 35 studies and the field study with 8 community-dwelling older adults were included in the final stage. Results: Fear for dementia had 4 dimensions with 14 attributes including cognitive factors (direct experience of precursor symptoms of dementia, indirect experience of dementia, preliminary knowledge of dementia, impossibility of cognitive control, and confidence in dementia), emotional factors (negative feelings and pessimistic thoughts), social factors (social isolation, economic instability, embarrassment), and behavioral factors (existing health problems, making efforts to maintain health, impossibility of body control, peripheral autonomic nervous system response) along with 34 indicators. Conclusion: This study is meaningful because it reveals the attributes of Korean elderly adults' fear for dementia. In addition, the results may serve as a basis for the early assessment and management of fear for dementia.

• 대한임상독성학회지
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• 제2권1호
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• pp.31-36
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• 2004

Three workers, field operators in lubricating oil processing of petroleum refinery industry were found unconscious by other worker. One of them who were exposed to an high concentration of H2S was presented with Glasgow Coma Score of 5, severe hypoxemia on arterial blood gas analysis, normal chest radiography, and normal blood pressure. On hospital day 7, his mental state became clear, and neurologic examination showed quadriparesis, profound spasticity, increased tendon reflexes, abnormal Babinski response, and bradykinesia. He was also found to have decreased memory, attention deficits and blunted affect which suggest general cognitive dysfunction, which improved soon. MRI scan showed abnormal signals in both basal ganglia and motor cortex, compatible with clinical findings of motor dysfunction. Neuropsychologic testing showed deficits of cognitive functions. SPECT showed markedly decreased cortical perfusion in frontotemporoparietal area with deep white matter. Another case was recovered completely, but the other expired the next day.

• 한국지능시스템학회논문지
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• 제13권2호
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• pp.148-153
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• 2003

서비스 거부 공격은 침입을 위한 침입시도 형태로 나타나며 대표적인 공격으로 Syn Flooding 공격이 있다. Syn Flooding 공격은 신뢰성 및 연결 지향적 전송서비스인 TCP의 종단간에 3-way handshake의 취약점을 이용한 공격이다. 본 논문에서는 네트워크 기반의 지능적 침입 방지 모델을 제안한다. 제안하는 모델은 Syn Flooding 공격을 탐지하기 위하여 패킷 정보를 수집하고 분석한다. 이 모델은 퍼지인식도(Fuzzy Cognitive Maps)를 적용한 결정모듈의 분석 결과를 활용하여 서비스 거부 공격의 위험도를 측정하고 공격에 대응하도록 대응모듈을 학습시킨다. 제안하는 모델은 Syn Flooding 공격의 위험을 격감 또는 방지하는 네트워크 기반의 지능적 침입 방지 모델이다.

• Biomolecules & Therapeutics
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• 제21권1호
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• pp.21-28
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• 2013

Microglia play a role in maintaining and resolving brain tissue homeostasis. In pathological conditions, microglia release pro-inflammatory cytokines and cytotoxic factors, which aggravate the progression of neurodegenerative diseases. Autophagy pathway might be involved in the production of pro-inflammatory cytokines and cytotoxic factors in microglia, though details of the mechanism remain largely unknown. In the present study, we examined the role of the autophagy pathway in activated BV2 microglia cells. In BV2 cells, rapamycin treatment activated the formation of anti-LC3-labeled autophagosomes, whereas the ATG5 depletion using siRNA-ATG5 prevented the formation of LC3-labeled autophagosomes, indicating that BV2 cells exhibit an active classical autophagy system. When treated with LPS, BV2 cells expressed an increase of anti-LC3-labeled dots. The levels of LC3-labeled dots were not suppressed, instead tended to be enhanced, by the inhibition of the autophagy pathway with siRNA-ATG5 or wortmannin, suggesting that LPS-induced LC3-labeled dots in nature were distinct from the typical autophagosomes. The levels of LPS-induced expression of iNOS and IL6 were suppressed by treatment with rapamycin, and conversely, their expressions were enhanced by siRNA-ATG5 treatment. Moreover, the activation of the autophagy pathway using rapamycin inhibited cell death of LPS-stimulated microglia. These results suggest that although microglia possess a typical autophagy pathway, the glial cells express a non-typical autophagy pathway in response to LPS, and the activation of the autophagy pathway suppresses the expression of iNOS and IL6, and the cell death of LPS-stimulated microglia.