• 한국비블리아학회지
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• 제20권1호
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• pp.165-179
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• 2009

초등학교 학교도서관은 기본적으로 교육 및 정보를 전달하는 장소이기 때문에 교사와 학생의 이용 편의성을 높이고 교사의 업무를 효과적으로 지원 할 수 있도록 구성되어야 한다. 일반적으로 공간 구성은 세부 공간 간의 기능을 잘 연결할 수 있도록 공간과 가구의 경제적 배치(LAYOUT)가 주된 목적이다. 따라서 공간과 가구를 잘 배치하여 이용자가 편리하고 교육효과를 높이기 위해서는 초등학교 학교도서관의 기능공간의 배치유형을 조사 분석하는데 본 연구의 목적이 있다. 이와 같은 측면에서 학교도서관의 전문화, 다원화, 개성화 하여야하는 목적과 교육환경 및 사회변화에 능동적으로 대처하고자 초등학교 도서관의 사용자인 학생 측면에서 현황을 파악하고 공간의 점유 특성을 분석하였으며 초등학교 도서관 계획시 보다 효율적인 공간계획이 이루어지도록 하였다.

• 전자공학회논문지B
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• 제31B권6호
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• pp.63-70
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• 1994

In this paper, we propose a fault simulation method based on primary output in combinational circuit. In the deterministic test pattern generation, each test pattern is genterated incrementally. The test pattern is applied to the primary inputs of circuit under test to simulate faults. We detect the faults with respect to each primary output. The fault detection with resptect to each primary output is reflected by the corresponding bit in the detection words, and efficient fault detection for the reconvergent fan-out stem is achieved with dynamic fault propagation. As an experimental result of the fault simulation with our method for the several bench mark circuits, we illustrated the good performance showing that the number of gates to be activated is much reduced as compared with other method which is not based on primary output.

• Journal of Welding and Joining
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• 제17권2호
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• pp.97-103
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• 1999

The dynamic resistance monitoring in primary circuit is one of the important issues. Because in-process and real time quality assurance of resistance spot weld is needed to increase the product reliability. In this study, new dynamic resistance detecting method is proposed as a practical manner of weld quality assurance using instantaneous current and voltage measured at the primary circuit. and also, various patterns of primary dynamic resistance curve are characterized with the macro photograph and the weldability lobe curve. It is found that the primary dynamic resistance patterns are basically similar to those of the secondary, but there is evident advantage such as no extra devices are needed to obtain the quality information and eventually real time feedback control will be possible.

• Journal of Communications and Networks
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• 제10권3호
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• pp.331-337
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• 2008

In this paper, we investigate survivability in wavelength division multiplexing (WDM) mesh networks and propose a new algorithm called improved shared-path protection (ISPP) to completely tolerate the double-link failures. Compared with previous algorithms for protecting double-link failures, i.e., shared-path protection (SPP) and shared-link protection (SLP), the advantage of ISPP is to allow primary paths and backup paths to share the mixed wavelength-links based on the proposed new rules in which some primary wavelength-links can be changed to mixed wavelength-links, which can be shared by primary paths and backup paths. In addition, some mixed wavelength-links also can be shared by different backup paths for saving resources. Simulation results show that ISPP algorithm performs better in resource utilization ratio and blocking probability than conventional SPP and SLP algorithms.

• Journal of information and communication convergence engineering
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• 제12권2호
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• pp.97-103
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• 2014

In spectrum sensing, there is a tradeoff between the probability of missed detection and the probability of a false alarm according to the value of the sensing threshold. Therefore, it is important to determine the sensing threshold suitable to the environment of cognitive radio networks. In this study, we consider a cognitive radio-based ad hoc network where secondary users directly communicate by using the same frequency band as the primary system and control their transmit power on the basis of the distance between them. First, we investigate a condition in which the primary and the secondary users can share the same frequency band without harmful interference from each other, and then, propose an algorithm that controls the sensing threshold dynamically on the basis of the transmit power of the secondary user. The analysis and simulation results show that the proposed sensing threshold control algorithm has low probabilities of both missed detection and a false alarm and thus, enables optimized spectrum sharing between the primary and the secondary systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권1호
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• pp.287-304
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• 2012

Spectrum sensing is an important functionality for cognitive users to look for spectrum holes before taking transmission in dynamic spectrum access model. Unlike previous works that assume perfect knowledge of the SNR of the signal received from the primary user, in this paper we consider a realistic case where the SNR of the primary user's signal is unknown to both fusion center and cognitive radio terminals. A Kalman filter based adaptive Takagi and Sugeno's fuzzy system is designed to make the global spectrum sensing decision based on the observed energies from cognitive users. With the capacity of adapting system parameters, the fusion center can make a global sensing decision reliably without any requirement of channel state information, prior knowledge and prior probabilities of the primary user's signal. Numerical results prove that the sensing performance of the proposed scheme outperforms the performance of the equal gain combination based scheme, and matches the performance of the optimal soft combination scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권12호
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• pp.4600-4616
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• 2021

In cognitive radio networks where unlicensed secondary users opportunistically access to licensed spectrum unused by licensed primary users, spectrum sensing is one of the key issues in order to effectively use the frequency resource. For enhancing the sensing performance in energy detection-based spectrum sensing, spatial diversity based on multiple antennas is utilized. However, the sensing performance can be degraded when antennas are spatially correlated, resulting in inducing the harmful interference to primary users. To overcome this problem, in this paper, an advanced energy detector is proposed. In the proposed sensing method, a weight matrix based on the eigenvalues of the spatial channels without any prior information on the primary signals is defined and utilized. In numerical simulations, it is shown that the proposed detector outperforms the conventional detector with regard to false-alarm and detection probabilities when antenna are spatially correlated.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권10호
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• pp.2455-2472
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• 2012

Although underlay spectrum sharing has been shown as a promising technique to promote the spectrum utilization in cognitive radio networks (CRNs), it may suffer bad secondary performance due to the strict power constraints imposed at secondary systems and the interference from primary systems. In this paper, we propose a two-phase based cooperative transmission protocol with the interference cancellation (IC) and best-relay selection to improve the secondary performance in underlay models under stringent power constraints while ensuring the primary quality-of-service (QoS). In the proposed protocol, IC is employed at both the secondary relays and the secondary destination, where the IC-based best-relay selection and cooperative relaying schemes are well developed to reduce the interference from primary systems. The closed-form expression of secondary outage probability is derived for the proposed protocol over Rayleigh fading channels. Simulation results show that, with a guaranteed primary outage probability, the proposed protocol can achieve not only lower secondary outage probability but also higher secondary diversity order than the traditional underlay case.

• ETRI Journal
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• 제30권1호
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• pp.21-32
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• 2008

Cognitive radio (CR) has been proposed as an effective technology for flexible use of the radio spectrum. The interference between primary users and CR users, however, becomes a critical problem when they are using adjacent frequency channels with different transmission power levels. In this paper, a robust CR orthogonal frequency division multiplexing (OFDM) architecture, which can effectively suppress interference to nearby primary users and overcome adjacent channel interference (ACI) to the CR user, is proposed. This new approach is characterized by adaptive data repetition for subcarriers under heavy ACI, and adaptive time spreading for subcarriers near the borders of the CR user's spectrum. The data repetition scheme provides extra power gain against the ACI coming from primary users. Time spreading guarantees an acceptable interference level to nearby primary users. By computer simulation, we demonstrate that, under a CR environment, the proposed CR OFDM architecture outperforms conventional OFDM systems in terms of throughput and BER performance.

• 정보관리학회지
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• 제28권4호
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• pp.201-220
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• 2011

이 연구에서는 우리나라 토목공학분야 연구자들이 참조하는 정보원의 유형을 인용분석을 통해 조사하였다. 분석 결과는 다음과 같다. 1) 주요 인용정보원은 학술지(55.7%)와 단행본(15.6%)과 회의자료(10.2%) 순이었다. 2) 출판 후 10년 이내(26.1%)의 문헌을 가장 많이 인용하였다. 3) 핵심학술지는 국내학술지였으며, 상위권 핵심학술지 선호도에서도 국내와 국외문헌의 의존도가 유사하였다. 4) 최신자료의 경우 국내문헌을, 출판 이후 경과시간이 오래된 자료의 경우 국외문헌을 선호하였다. 5) 국내외 모든 핵심학술지들이 영향력 지수와 즉시성 지수의 값이 동시에 높게 나타나지 않았다.