• Journal of Communications and Networks
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• 제9권3호
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• pp.274-281
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• 2007

In this paper, we present a hybrid multi-antenna technique that can minimize the outage probability by combining the diversity and beamforming techniques. The hybrid technique clusters the transmission antennas into multiple groups and exploit diversity among different groups and beamforming within each group. We analyze the performance of the resulting hybrid technique for an arbitrary correlation among the transmission antennas. Through the performance analysis, we derive a closed-form expression of the outage probability for the hybrid technique. This enables to optimize the antenna grouping for the given spatial correlation. We show through numerical results that the hybrid technique can balance the trade-offs between diversity and beamforming according to the spatial correlation and that the optimally designed hybrid technique yields a much lower outage probability than the diversity or beamforming technique does in partially correlated fading channels.

• 한국수자원학회논문집
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• 제43권8호
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• pp.757-767
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• 2010

본 연구는 확률강우량에 대한 공간분포 추정시 신뢰도를 향상시키는데 있어서 외부변수 사용의 유효성을 평가하기 위하여 확률강우량과 단일 보조변수로서 지형특성인자들과의 상관관계를 고려한 KED 기법을 적용하였으며, 그 결과 강우공간분포 및 유역평균강우량의 추정에 있어서 확정론적 공간보간기법 및 크리징 기법과 대체로 비슷한 결과를 나타내는 것으로 분석되었으며, KED 및 크리징 기법에 대한 교차검증 결과 보조변수로서 표고를 사용한 KED 기법이 가장 좋은 결과를 나타내고는 있으나 다른 기법들과 비교했을 때 큰 차이를 보이지 않는 것으로 분석되었다.

• 한국지반신소재학회논문집
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• 제21권3호
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• pp.1-10
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• 2022

본 논문에서는 지반 구조물의 재료 물성치에 대한 추계장 세트를 이용하여 재료 물성치의 공간적 임의성 및 확률 특성을 역추정한다. 이러한 추정된 재료 물성치의 확률분포 및 확률특성을 이용하여 구조 형상에 대한 위상 최적화를 수행하고, 기존의 결정론적 위상 최적화 결과와 비교한다. 재료 물성치에 대한 한 세트의 추계장들을 생성하고, 각 추계장에서 재료 물성치의 공간적 임의성을 모사한다. 각 추계장에서 재료 물성치의 부분값들을 이용하여 실제 재료 물성치의 확률분포와 확률 특성을 추정한다. 추정된 실제 재료 물성치의 확률특성을 추계장 세트의 확률 특성과 비교한다. 또한, 임의성을 가진 재료탄성계수를 가지는 지반구조물의 최적화 응답변화도와 임의성이 없는 재료탄성계수를 가지는 지반구조의 응답변화도를 비교한다. 따라서, 실제 재료 물성치의 공간적 임의성을 고려한 정량화된 확률론적 위상 최적화 결과를 얻을 수 있다.

• 한국환경과학회지
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• 제20권12호
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• pp.1541-1551
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• 2011

This study applied the Bayesian method for the quantification of the parameter uncertainty of spatial linear mixed model in the estimation of the spatial distribution of probability rainfall. In the application of Bayesian method, the prior sensitivity analysis was implemented by using the priors normally selected in the existing studies which applied the Bayesian method for the puppose of assessing the influence which the selection of the priors of model parameters had on posteriors. As a result, the posteriors of parameters were differently estimated which priors were selected, and then in the case of the prior combination, F-S-E, the sizes of uncertainty intervals were minimum and the modes, means and medians of the posteriors were similar to the estimates using the existing classical methods. From the comparitive analysis between Bayesian and plug-in spatial predictions, we could find that the uncertainty of plug-in prediction could be slightly underestimated than that of Bayesian prediction.

• 국토계획
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• 제54권2호
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• pp.5-16
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• 2019

The purpose of this study is to analyze the spatial characteristics of business-type-changed parcel in the Hongik-University commercial area, from the view point of commercial gentrification. A commercial gentrification occurs through a business-type-change in a spatial basic unit (microscopic spatial unit such as parcel) of an area which has not been considered in relavent policies and research. So, this study analyzed the spatial characteristics of business-type-changed parcels using the Cox's proportional hazard regression model. The main results of this study are as follows. First, as new developments in the adjacent area occur, the business-type-change probability increases. Second, by the commercial area division, the business-type-change probability is different. Finally, the accessibility is better, the probability is higher. These results could suggest that a consideration of the spatial characteristics form microscopic viewpoint is necessary to understand the commercial gentrification. And these could be used as basic data for a gentrification diagnostic and management system, which can predict gentrification from the view point of business-type-change on the basis of a parcel.

• 한국농공학회논문집
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• 제60권3호
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• pp.63-70
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• 2018

In this study, a simple probabilistic approach using equivalent coefficient of consolidation ($c_e$) was proposed to consider the spatial variability of coefficient of vertical consolidation ($c_v$), and the effect of the probability distribution of coefficient of consolidation on degree of consolidation in heterogeneous soil was investigated. The statistical characteristics of consolidation coefficient were estimated from 1,226 field data, and four probability distributions (Normal, Log-normal, Gamma, and Weibull) were applied to consider the effect of probability distribution. The random fields of coefficient of consolidation were generated based on Karhunen-Loeve expansion. Then, the equivalent coefficient of consolidation was calculated from the random field and used as the input value of consolidation analysis. As a result, the probabilistic analysis can be performed effectively by separating random field and numerical analysis, and probabilistic analysis was performed using a Latin hypercube Monte Carlo simulation. The results showed that the statistical properties of $c_e$ were changed by the probability distribution and spatial variability of $c_v$, and the probability distribution of $c_v$ has considerable effects on the probabilistic results. There was a large difference of failure probability depend on the probability distribution when the autocorrelation distance was small (i.e., highly heterogeneous soil). Therefore, the selection of a suitable probability distribution of $c_v$ is very important for reliable probabilistic analysis of consolidation.

• 한국컴퓨터정보학회논문지
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• 제14권10호
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• pp.207-215
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• 2009

최근 도시화 율이 증가됨에 따라 발생되는 도시의 범죄 예방을 위하여 컴퓨터정보기술과 GIS 기술을 이용한 범죄 공간의 분석에 대한 연구가 활발하게 이루어지고 있다. 본 논문에서는 정적인 환경에서 도시공간정보에 포함된 지역특성을 이용하여 단위 셀별 우범 위험도를 계량화하여 래스터 형태의 확률 지도를 구성하였다. 지형적 특성에 의한 상대적 위험도, 시설물에 의한 상대적 위험도, 수목이나 하천에 의한 위험도 등을 기본으로 하여 위험도 확률 지도를 구축한다. 이를 통합한 위험도 확률 지도를 구할 때는 각각의 단위 위험도에 기후나 계절적 요인에 의해 가중치를 적용한 후 평균하게 된다. 또한 일회성 분석이 아닌 범죄 발생 상대적 위험지수의 패턴을 판독키로 하여 전체 위험도의 확률 지도를 생성하여 이후 발생하는 범죄의 유형을 계량화하는 확률지도에 추가적으로 적용하어 정적인 정보가 아닌 시간의 흐름에 따라 범죄 위험도 확률지도가 달라질 수 있는 모델과 시뮬레이션 하는 방법론을 제안하였다.

• Geomechanics and Engineering
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• 제36권6호
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• pp.631-640
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• 2024

In the traditional slope stability analysis, ignoring the spatial variability of slope soil will lead to inaccurate analysis. In this paper, the K-L series expansion method is adopted to simulate random field of soil strength parameters. Based on Random Limit Equilibrium Method (RLEM), the influence of variation coefficient and fluctuation range on reliability of soil slope supported by micro-pile is investigated. The results show that the fluctuation ranges and the variation coefficients significantly influence the failure probability of soil slope supported by micro-pile. With the increase of fluctuation range of soil strength parameters, the mean safety factor of the slope increases slightly. The failure probability of the soil slope increases with the increase of fluctuation range when the mean safety factor of the slope is greater than 1. The failure probability of the slope increases by nearly 8.5% when the fluctuation range is increased from δ_v=2 m to δ_v =8 m. With the increase of the variation coefficient of soil strength parameters, the mean safety factor of the slope decreases slightly, and the probability of failure of soil slope increases accordingly. The failure probability of the slope increases by nearly 31% when the variation coefficient increases from COV_c=0.2, COV_φ=0.05 to COV_c=0.5, COV_φ=0.2.

• 말소리와 음성과학
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• 제2권3호
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• pp.141-148
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• 2010

In this paper, voice activity detection (VAD) for dual-channel noisy speech recognition is proposed in which spatial cues are employed. In the proposed method, a probability model for speech presence/absence is constructed using spatial cues obtained from dual-channel input signal, and a speech activity interval is detected through this probability model. In particular, spatial cues are composed of interaural time differences and interaural level differences of dual-channel speech signals, and the probability model for speech presence/absence is based on a Gaussian kernel density. In order to evaluate the performance of the proposed VAD method, speech recognition is performed for speech segments that only include speech intervals detected by the proposed VAD method. The performance of the proposed method is compared with those of several methods such as an SNR-based method, a direction of arrival (DOA) based method, and a phase vector based method. It is shown from the speech recognition experiments that the proposed method outperforms conventional methods by providing relative word error rates reductions of 11.68%, 41.92%, and 10.15% compared with SNR-based, DOA-based, and phase vector based method, respectively.

• 한국수자원학회논문집
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• 제43권11호
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• pp.933-944
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• 2010

본 논문에서는 확률강우량에 대한 공간분포 추정에 있어서 공간변동성에 따른 불확실성을 평가하기 위하여 지구통계 학적 추계모의기법인 CEM과 SGS 기법을 비교하였다. CEM과 SGS를 이용한 추계모의에 있어서 공간상관구조의 재생성, 확률강우량에 대한 불확실성 평가측도로서 실현치에 대한 통계치(표준편차, 변동계수, 사분위수 범위 및 범위)의 공간분포, 유역평균강우량의 불확실성 분포의 경우 두 기법이 대체로 비슷한 결과를 보이는 것으로 분석되었다. 그러나 모의 효율성 측면에서는 CEM이 SGS에 비해 우수한 결과를 나타내는 것으로 분석되었다.