• Earthquakes and Structures
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• 제17권3호
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• pp.271-282
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• 2019

Knowing the response of buildings to earthquakes is very important in order to ensure that a structure is able to withstand a given level of ground shaking. Thus, nonlinear dynamic earthquake engineering analyses are unavoidable and are preferable procedure in the seismic assessment of buildings. In order to estimate seismic performance on the basis of the hazard at the site where the structure is located, the selection of appropriate seismic input is known to be a critical step while performing this kind of analysis. In this paper, seismic analysis is performed for a four-story reinforced concrete ISPRA frame structure which is designed according to Eurocode 8 (EC8). A total of 90 different earthquake scenarios were selected, 30 for each of three target spectrums, EC8 spectrum, Uniform Hazard Spectrum (UHS), and Conditional Mean Spectrum (CMS). The aim of this analysis was to evaluate the average maximum Inter-story Drift Ratio (IDR) for each target spectrum. Time history analysis for every earthquake record was obtained and, as a result, IDR as the main measure of damage were presented in order to compare with defined performance levels of reinforced concrete bare frames.

• Journal of information and communication convergence engineering
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• 제9권2호
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• pp.166-171
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• 2011

This paper investigates the design issues of spectrum sensing in the cognitive radio (CR) networks of opportunistic unlicensed spectrum access. The cognitive radios can perform a communication using the incumbent user spectrum band without the interference caused by the cognitive radio users. In this case, the cognitive radios must know the real-time radio environments of the incumbent user spectrum band using the spectrum sensing, beacon signal, and geo-location database access. Then in this paper, we are going to provide spectrum sensing issues which include the sensing techniques, the regulatory requirements, the analysis of DTV detection threshold, and main considerations associated with the spectrum sensing design in cognitive radio systems. Also, this paper introduces design trade-offs in order to optimize the sensing parameters such as sensing time and sensing complexity.

• 한국전자파학회논문지
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• 제30권6호
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• pp.452-466
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• 2019

최근 전파 자원의 수요 급증에 따라 전파자원의 적기 확보의 중요성이 증대되고 있다. 본 논문에서는 이러한 전파자원 확보를 위한 수단으로서 전파법 제6조에서 규정하고 있는 주파수 효율개선 시책의 시행 우선순위를 평가하는 방안을 제시한다. 전파법에서 규정하는 주파수 효율개선 시행을 위한 고려사항으로부터 평가지표를 도출하고, 지표측정 결과를 수요 시급성과 확보 용이성의 두 범주를 축으로 하는 우선순위 평가 매트릭스를 통해 4단계로 우선순위를 평가하는 방안과 제안된 평가 방안의 실제 적용에 필요한 착안사항 등이 제시되었다. 이러한 평가방식 적용을 통해 선제적인 주파수 확보, 공급뿐만 아니라, 이용자 보호, 전파기반 신사업 창출기회 확대 등을 기대할 수 있다.

• 한국통신학회논문지
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• 제37A권11호
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• pp.943-951
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• 2012

본 논문에서는 비정규 충격성 잡음 환경에서 협력 무선인지 네트워크를 위한 순서 기반 스펙트럼 센싱 기법을 제안한다. 구체적으로는 잡음을 이변수 등방형 대칭 알파 안정 (bivariate isotropic symmetric ${\alpha}$-stable) 분포를 따르는 것으로 모형화하고, 그에 알맞은 관측 샘플의 순서와 일반화된 우도비 검정 기반 협력 스펙트럼 센싱 기법을 제안한다. 모의실험을 통해 비정규 잡음 환경에서 제안한 기법이 기존의 기법에 비해 더 좋은 스펙트럼 센싱성능을 가짐을 보인다.

• 한국수학교육학회지시리즈A:수학교육
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• 제22권1호
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• pp.67-68
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• 1983

In this note we consider properties for the discreteness of the spectrum of second-order differential operators. If we give some conditions, then the spectrum of any self-adjoint extension of $A_{0}$ , $A_{0}$ u=$\alpha$[u], D( $A_{0}$ )= $C_{0}$ $^{\infty}$(0.1) is discrete.1) is discrete.

• Journal of Communications and Networks
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• 제16권2호
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• pp.209-216
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• 2014

Cognitive radio (CR) has been proposed to solve the spectrum utilization problem by dynamically exploiting the unused spectrum. In CR networks, a spectrum selection scheme is an important process to efficiently exploit the spectrum holes, and an efficient channel allocation scheme must be designed to minimize interference to the primary network as well as to achieve better spectrum utilization. In this paper, we propose a multichannel selection algorithm that uses spectrum hole prediction to limit the interference to the primary network and to exploit channel characteristics in order to enhance channel utilization. The proposed scheme considers both the interference length and the channel capacity to limit the interference to primary users and to enhance system performance. By using the proposed scheme, channel utilization is improved whereas the system limits the collision rate of the CR packets.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2006년도 춘계종합학술대회
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• pp.549-554
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• 2006

The objective of this paper is to propose a system by means of which the utilization of radio frequency spectrum may be improved from the state of extreme inefficiency at the present time in Kazakhstan to a state of efficiency and equilibrium in the future. The main solutions to efficiently use radio frequency spectrum in Kazakhstan will be described in this paper. There are 'Spectrum Utilization, Spectrum Sharing and Reuse the Spectrum' in which the radio frequency can be propagated in wide range using smalt amount of spectrum, or broadcast several channels via one spectrum sharing. In order to embed these systems in practice it will be better to make modifications consider Government policy and geographical and social requirements.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권8호
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• pp.2157-2169
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• 2023

In order to handle the problem that puncture patterns will change the position distribution of original information bits and frozen bits in polar codes, which affects performance of puncture polar codes further, a minimum row weight and polar spectrum based puncture polar codes construction algorithm (called PA-MRWP) is proposed in this paper. The algorithm calculates row weight of generator matrix and sorts the row weight in ascending order first. Next, the positions with the minimum row weight are selected as initial puncture positions. If the rows with the same row weight cannot all be punctured, polar spectrum based auxiliary puncture scheme is used. In sub-channels with the same row weight, rows corresponding to the polarized sub-channels with higher reliability are selected as puncture positions to construct puncture vector, and the reliability is calculated based on polar spectrum. It is actually a two-step selection strategy, the proposed minimum row weight puncture (MRWP) algorithm is used for primary selection and polar spectrum based auxiliary puncture is used for adjustment. Simulation results show that, compared with worst quality puncture (WQP) algorithm, the proposed PA-MRWP algorithm and Gaussian approximation-aided minimum row weight puncture (GA-MRWP) algorithm provide gains of about 0.46 dB and 0.29 dB at bit error rate (BER) of 10^-4, respectively when code length N=400, code rate R=1/2. In addition, the proposed puncture algorithms improve the BER performance significantly with respect to quasi-uniform puncture (QUP) algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권4호
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• pp.1489-1503
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• 2018

Spectrum reuse has attracted much concern of researchers and scientists, however, the dynamic spectrum access is challenging, since an individual secondary user usually just has limited sensing abilities. One key insight is that spectrum usage forecasting among secondary users, this inspiration enables users to obtain more informed spectrum opportunities. Therefore, spectrum usage forecasting is vital to cognitive radio networks (CRNs). With this insight, a spectrum usage forecasting model for the occurrence of primary users prediction is derived in this paper. The proposed model is based on auto regressive enhanced primary user emergence reasoning (AR-PUER), which combines linear prediction and primary user emergence reasoning. Historical samples are selected to train the spectrum usage forecasting model in order to capture the current distinction pattern of primary users. The proposed scheme does not require the knowledge of signal or of noise power. To verify the performance of proposed spectrum usage forecasting model, we apply it to the data during the past two months, and then compare it with some other sensing techniques. The simulation results demonstrate that the spectrum usage forecasting model is effective and generates the most accurate prediction of primary users occasion in several cases.

• 패션비즈니스
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• 제15권1호
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• pp.92-102
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• 2011

The purpose of this research is to study the types of name spectrum and their characteristics of domestic men's wear brands focusing on formal and casual wear and also examine the differences based on the type of brands' product and brand style. Total 184 of men's wear brands, which were consisted of 66 formal wear brands and 84 casual wear brands, were selected from '2009 Korea Fashion Yearbook'. For data analysis, quantitatively evaluated the frequency and qualitatively evaluated the image of brand product and the meaning of brand name. The result as follows; 1. The domestic fashion brands for men's wear appeared to have four types of name spectrum. The descriptive name was the most frequently showed, and followed by arbitrary, suggestive, and coined name. For formal wear brands, four types of name spectrum were appeared in the order of descriptive, suggestive, coined, and arbitrary name. In casual wear brands, three types of name spectrum were appeared in the order of descriptive, arbitrary, and suggestive name. 2. The characteristics of men's brand name according to their name spectrum was as follows.; In the descriptive brand names, person's name was used the most and some ascribed the characteristics, feature or geographic location of the product. The suggestive brand names contained images and symbols of the product and also implied the relevant benefit information in a particular product context. In the arbitrary brand name, they imply the various meanings according to the product and are made up of either coined or natural. For the coined name, some bear the ideology or symbolized the characteristics of product itself. 3. The descriptive name spectrum showed the most in domestic menswear brands, regardless of the brand type. Except this, there were differences in the type and the frequency of name spectrum depending on the brand type.