• Nuclear Engineering and Technology
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• 제34권6호
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• pp.586-595
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• 2002

The Seismic probabilistic risk assessment (SPRA) or seismic margin assessment (SMA) have been used for the seismic safety evaluation of nuclear power plant structures and equipments. For the SPRA or SMA, the reference response spectrum should be defined. The site-specific median spectrum has been generally used for the seismic fragility analysis of structures and equipments in a Korean nuclear power plant Since the site-specific spectrum has been developed based on the peak ground motion parameter, the site-specific response spectrum does not represent the same probability of exceedance over the entire frequency range of interest. The uniform hazard spectrum is more appropriate to be used in seismic probabilistic risk assessment than the site- specific spectrum. A method for modifying the seismic fragility parameters that are calculated based on the site-specific median spectrum is described. This simple method was developed to incorporate the effects of the uniform hazard spectrum. The seismic fragility parameters of typical NPP components are modified using the uniform hazard spectrum. The modification factor is used to modify the original fragility parameters. An example uniform hazard spectrum is developed using the available seismic hazard data for the Korean nuclear power plant (NPP) site. This uniform hazard spectrum is used for the modification of fragility parameters.

• 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.

• 산업경영시스템학회지
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• 제35권2호
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• pp.181-188
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• 2012

The fee system on spectrum usage is a usage fee that is charged for using spectrum provided by a wireless tower, and is used for management and promotion of the waves. The current fee system for spectrum usage in South Korea has faced many problems, such as complex calculation for fees, unjustified charges, unfairness in cost sharing among providers, and general inefficiency of operation. This study focuses on comparison of fee systems for spectrum usage of South Korea and other foreign countries, extraction of the root causes and problems by case analyses, and recommendation for better solutions to make a reasonable fee system for spectrum usage. The result of this study can be used as a solution to render spectrum usage more effective.

• ETRI Journal
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• 제41권2호
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• pp.224-234
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• 2019

This paper proposes a new spectrum forecasting (SF) model to estimate the spectrum demands for future mobile broadband (MBB) services. The model requires five main input metrics, that is, the current available spectrum, site number growth, mobile data traffic growth, average network utilization, and spectrum efficiency growth. Using the proposed SF model, the future MBB spectrum demand for Malaysia in 2020 is forecasted based on the input market data of four major mobile telecommunication operators represented by A-D, which account for approximately 95% of the local mobile market share. Statistical data to generate the five input metrics were obtained from prominent agencies, such as the Malaysian Communications and Multimedia Commission, OpenSignal, Analysys Mason, GSMA, and Huawei. Our forecasting results indicate that by 2020, Malaysia would require approximately 307 MHz of additional spectrum to fulfill the enormous increase in mobile broadband data demands.

• 전자통신동향분석
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• 제34권6호
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• pp.17-27
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• 2019

This paper introduces the 5G spectrum auction in Germany that occurred last summer and ended overheatedly after an extraordinarily long period. We describe the context of the latest German spectrum auction and trace the participants' bidding behavior. This case details the trend of the 5G spectrum auction and the factors that affect the spectrum auction as follows: First, it is determined that investment obligations that force network installations can be a financial burden to mobile network operators (MNOs) and require a careful approach. Second, excess demands can cause auction overheating and the spectrum supply volume needs to be determined by a proper demand forecast and investment incentive. Third, 'Set-Aside' for local usage aids in developing the vertical industry; however it limits the spectrum supply for mobiles and leads to higher bidding prices. Fourth, a modified adoption of a typical spectrum auction can alleviate MNO's financial burdens to secure the broadband spectrum. Finally, competition to secure the necessary bandwidth in the situation of limited spectrum supply may delay the process of the spectrum auction, causing it overheated.

• Journal of Information Technology Applications and Management
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• 제21권4_spc호
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• pp.431-447
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• 2014

Demand of spectrum resource is tremendously increasing and this trend will continue as more IT services such as cloud computing, smart devices, Internet of Things are provided through wireless network. Recent development of spectrum sharing technology has drawn attention to spectrum policy makers as a promising way to overcome the expected spectrum shortage problem. However, technology-based solution to spectrum shortage problem may not be sustainable since the solution affect only one aspect of spectrum sharing ecosystem. To understand the whole picture of spectrum shortage problem, policies to vitalize spectrum sharing ecosystem were proposed based on the analysis of System Dynamics causal map in the previous study. This study compares and analyzes the effect of those proposed vitalization policies by using System Dynamics simulation. Among seven alternative policies, combined application of demand acceleration policy and technology development policy was found to be more effective for better utilization of spectrum. The effect of demand acceleration policy was offset when other policies are applied together except supply acceleration policy which shows better spectrum sharing.

• Journal of Radiation Protection and Research
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• 제32권1호
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• pp.9-13
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• 2007

원통형 용기에 담긴 액체 혼합선원의 HPGe 검출기 교정용 스펙트럼으로부터 스펙트럼 분석 교육을 위한 모사 스펙트럼을 개발하였다. 모사 스펙트럼은 측정된 스펙트럼으로부터 피크를 분리한 후, 채널별 계수들의 변동이 제거된 스펙트럼을 결합한 것이다. 모사 스펙트럼의 통계적 변동은 Box-Muller 함수로 만들었다. 이 스펙트럼은 18개의 피크를 포함하고 있다. 각 피크의 중심 위치 및 면적 등은 정확하게 정의되었다. 개발된 스펙트럼은 교정용 스펙트럼, 시료 스펙트럼, 백그라운드 스펙트럼 그리고 기하학적 및 동시합성 보정을 위한 스펙트럼이다.

• 한국멀티미디어학회논문지
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• 제18권12호
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• pp.1439-1444
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• 2015

Measuring spectral reflectance can be regarded as obtaining inherent color parameters, and spectral reflectance has been used in image processing. Model-based spectrum recovering, one of the method for obtaining spectral reflectance, uses ordinary camera with multiple illuminations. Conventional model-based methods allow to recover spectral reflectance efficiently by using only a few parameters, however it requires some parameters such as power spectrum of illuminations and spectrum sensitivity of camera. In this paper, we propose an enhanced model-based spectrum recovering method without pre-measured parameters: power spectrum of illuminations and spectrum sensitivity of camera. Instead of measuring each parameters, spectral reflectance can be efficiently recovered by estimating and using the spectrum characteristic matrix which contains spectrum parameters: basis function, power spectrum of illumination, and spectrum sensitivity of camera. The spectrum characteristic matrix can be easily estimated using captured images from scenes with color checker under multiple illuminations. Additionally, we suggest fast recovering method preserving positive constraint of spectrum by nonnegative basis function of spectral reflectance. Results of our method showed accurately reconstructed spectral reflectance and fast constrained estimation with unmeasured camera and illumination. As our method could be conducted conveniently, measuring spectral reflectance is expected to be widely used.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권11호
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• pp.3751-3774
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• 2014

With the rapid development of wireless communication, the confliction between the scarce frequency resources and the low spectral efficiency caused by the stationary spectrum sharing strategies seriously restricts the evolution of the future mobile communication. For this purpose, cognitive radio (CR) emerges as one of the most promising inventions which can overcome the spectrum shortage. As the key technology and main objective of CR, spectrum sharing can make full use of the limited spectrum, alleviate the scarcity of frequency resources and improve the system utilities, playing thereby an important role in improving the system performance of cognitive radio networks (CRNs). In this survey, the spectrum sharing in CRNs is discussed in terms of the sharing process, mainstream sharing technologies and spectrum sharing models. In particular, comparisons of different spectrum sharing strategies are concluded, as well as that of different spectrum sensing schemes in sharing procedure. Moreover, some application examples of the spectrum sharing in CRNs, such as smart grid, public safety, cellular network and medical body area networks are also introduced. In addition, our previous related works are presented and the open research issues in the field of spectrum sharing are stated as well.

• Journal of information and communication convergence engineering
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• 제14권1호
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• pp.1-8
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• 2016

Spectrum sensing in cognitive radio networks allows secondary users to sense the unused spectrum without causing interference to primary users. Cognitive radio requires more accurate sensing results from unused portions of the spectrum. Accurate spectrum sensing techniques can reduce the probability of false alarms and misdetection. In this paper, a two-stage spectrum sensing scheme is proposed for cooperative spectrum sensing in cognitive radio networks. In the first stage, spectrum sensing is executed for each secondary user using energy detection based on double adaptive thresholds to determine the spectrum condition. If the energy value lies between two thresholds, a fuzzy logic scheme is applied to determine the channel conditions more accurately. In the second stage, a fusion center combines the results of each secondary user and uses a fuzzy logic scheme for combining all decisions. The simulation results show that the proposed scheme provides increased sensing accuracy by about 20% in some cases.