• Journal of the Korean Geotechnical Society
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• v.26 no.10
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• pp.39-47
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• 2010

In order to investigate the effect of variation characteristics of compression index on the spatial distribution of consolidation settlement, this study presents the estimation methods of the distribution of consolidation settlement and compares the estimated settlements. When the variation of compression index is considerable, the ordinary cokriging is more reliable in estimating the compression index than ordinary kriging because smoothing effect of ordinary cokriging is smaller than that of ordinary kriging. The spatial distribution of consolidation settlement estimated by considering both the variation of compression index and void ratio (CASE-1) is different from that estimated by using the mean value of all soil properties (CASE-2). The settlement of CASE-1 shows the larger variation at short distances rather than that of CASE-2. Whereas the spatial settlement distribution of CASE-1 is affected by the spatial distributions of compression index as well as the thickness of consolidation layer, that of CASE-2 is significantly influenced by the distribution of consolidation layer thickness.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.5
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• pp.577-584
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• 2009

Fusion of decisions in wireless sensor networks having flexibility on energy efficiency is studied in this paper. Two representative distributions, the generalized Gaussian and $\alpha$-stable probability density functions, are used to model non-Gaussian noise channels. By incorporating noise channels into the parallel fusion model, the optimal fusion rules are represented and suboptimal fusion rules are derived by using a large signal-to-noise ratio(SNR) approximation. For both distributions, the obtained suboptimal fusion rules are same and have equivalent form to the Chair-Varshney fusion rule(CVR). Thus, the CVR does not depend on the behavior of noise distributions that belong to the generalized Gaussian and $\alpha$-stable probability density functions. The simulation results show the suboptimality of the CVR at large SNRs.

• Journal of Energy Engineering
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• v.4 no.3
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• pp.394-401
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• 1995

본 연구는 중심부에 액체, 외주부에 산화제가 흐르는 기액 동축분류의 유동장에 대한 것이다. 기액 동축 분사기는 연료의 분사량이 적은 소형 연소시스템을 고려하여, 실험은 연공비(W1/Wa)가 0.6 이하를 대상으로, 물과 공기를 사용하여 분사조건에 따른 분무특성과 기액 2상 분무류의 기본구조를 조사하여 액적의 확산, 기액혼합특성에 대하여 검토하여 다음과 같은 결론을 얻었다. 반경방향 기상속도분포 및 액적유속분포는 분구직경 및 분사조건에 관계없이 정규분포에 가까운 형태를 취하고 있으며, 각각 식 (2) 및 (3)으로 나타낼 수 있다. 기상속도는 반치폭은 축방향에 따라 일정한 구배 (≒4.6)로서 증가하며, 기상만의 단상분류의 구배(≒6)에 비해서 완만하다. 액적유속 반치폭은 축방향에 따라 더욱 완만한 구배(≒3.1)로서 증가한다. 무차원 액적유속분포는 축방향에 따라 일정한 구배(n≒1.5)로서 감소한다. 액적의 확산은 상대적으로 기액유량비가 클수록 효과적으라고는 말할 수 없고, 최대 확산을 이루는 최적의 기액유량비가 존재한다.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.2
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• pp.100-116
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• 2019

Urban green spaces, as a means to mitigate social problems and environmental risks, are getting more attention in evaluating urban environment. The inequity of green space distribution is becoming a major issue in urban planning and management. This study investigated the characteristics of green space in 3 districts (Jung-gu, Dongdaemun-gu, Seongdong-gu), that are composed of 46 administrative divisions in central Seoul, to analyze the environmental equity of urban green spaces. The correlations between the amount of green space, including the coverage of street trees, and the socioeconomic status of each administrative division were analyzed. To deduce the effects of plant coverage on the urban temperature regime, the relationship between the normalized difference of vegetation index (NDVI) and land surface temperature (LST) was analyzed. The research revealed that the mean NDVI of an administrative division was negatively correlated with the percentage of basic living recipients and disabled people. The LST of a division with low NDVI was higher due to the lack of green coverage. Such environmental inequities were closely related to residential building type, which was strongly affected by the economic status of residents. The LST of an apartment area was $2.0^{\circ}C$ lower than that of single-family houses and multi-housing areas. This is expected as the average NDVI of the apartment area was more than twice as high as the other environments considered in this study. The inequity can be exacerbated without urban planning which is deliberately designed to reduce it.

• Journal of Korea Multimedia Society
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• v.14 no.10
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• pp.1221-1228
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• 2011

The speech recognition system works well in general indoor environment. However, the recognition performance is dramatically decreased when the system is used in the real environment because of the several noises. In this paper we proposed CSFN-CMVN to improve the recognition performance of the existing CSFN(Cepstral distance based SFN). The CSFN-CMVN method is a combined method of cepstral normalization with CSFN that normalizes silence features using cepstral euclidean distance to classify speech/silence for better performance. From the test results using Aurora 2.0 DB, we could find out that our proposed CSFN-CMVN improves about 7% of more average word accuracy in all the test sets comparing with the typical silence features normalization SFN-I. We can also get improved accuracy of 6% and 5% respectively in compared tests with the conventional SFN-II and CSFN, showing the effectiveness of our proposed method.

• The Korean Journal of Applied Statistics
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• v.34 no.4
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• pp.611-622
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• 2021

With a wide recognition that financial time series typically exhibits asymmetry patterns in volatility so called leverage effects, various asymmetric GARCH(1, 1) processes have been introduced to investigate asymmetric volatilities. A lot of researches have also been directed to non-stationary volatilities to deal with frequent high ups and downs in financial time series. This article is concerned with both asymmetric and non-stationary GARCH-type models. As a subsequent paper of Choi et al. (2020), we review various asymmetric and non-stationary GARCH(1, 1) processes, and in turn propose how to compare competing models using a parametric bootstrap methodology. As an illustration, Dow Jones Industrial Average (DJIA) is analyzed.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.446-448
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• 2011

본 논문에서는 조명 보정과 지역적인 밝기 정보를 이용한 유해 영상에서의 피부색 검출 방법을 제안한다. 첫번째, 조명의 영향을 줄이기 위하여 입력 영상을 히스토그램 평활화하여 명암 값의 분포가 한쪽으로 치우치거나 균일하지 못한 영상의 명암 값 분포를 균일화 시켜 영상을 향상될 수 있도록 한다. 그 다음, 평활화 시킨 영상을 25 개의 블록으로 분할한 후, 각 블록에서의 밝기 값에 대한 통해 평균과 왜도를 구한다. 구해진 값들을 영상의 임계값으로 설정하여 이진화 시킨다. 그리고, 평활화시킨 영상의 RGB 값을 Lab 컬러 공간으로 변환한다. 변환된 컬러 공간내의 조명 성분 값인 L(Luminance)값을 추출하여 이를 역변환 한다. 역변환한 L 값은 비정규 조명을 갖는 유해 영상의 조명에 민감한 영향을 제거하기 위하여 평활화 영상에 합한다. 마지막으로, 밝기 임계값을 통해서 얻어진 이진영상내의 객체 영역과 RGB 피부색 임계값을 통한 조명 보정된 평활화 영상내의 피부색 영역의 공통된 영역을 결과값으로 추출한다.

• The Korean Journal of Applied Statistics
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• v.7 no.1
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• pp.35-46
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• 1994

We propose the nonparametric rank-like test for the location parameter in the bivariate changepoint model. Empirical powers between the parametric test and nonparametric test are compared. These results show that rank-like test is better than parametric method except bivariate normal null distribution. The point estimators for the changepoint are also compared by the empirical mean squared errors.

• The Korean Journal of Applied Statistics
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• v.3 no.1
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• pp.11-25
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• 1990

The objective of this paper is to propose a nonparametric distribution-free test for ordered alternatives in k crossed factor designs by using the concepts of combined factor and within-blocks ranks. We investigate the asymptotic normality of the proposed test statistic and the Pitman efficiencies. We also compared the small empirical powers of the tests considered in this paper by Monte Carlo study. Thus we can conclude that the proposed test is efficient and robust for the underlying distribution.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10b
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• pp.325-327
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• 2001

본 논문은 온라인 문자 인식을 연속 밀도 HMM의 구조의 최적화 문제를 다룬다. 최적이란 최소한의 모델 파라미터를 사용하여 최소한의 오류를 허용하는 것이라고 정의할 수 있다. 본 연구에서는 HMM 구조의 최적화를 위해 Bayesian 모델 선택 방법론을 사용한다. 먼저 잘 알려진 BIC(Bayesian Information Criterion)을 적용해보고, 그것을 HMM의 복잡한 구조에 적합하도록 본 논문에서 제안한 HBIC(HMM-Oriented BIC)와 비교해본다. BIC는 모델의 사전 확률 분포를 추정하지 않고 다변량 정규분포라고 가정하는데 비해 HBIC는 모델의 각 파라미터로부터 사전 확률을 추정한 후 그것들을 사용함으로써 더 좋은 결과를 얻도록 한다. 실험 결과 BIC와 HBIC 둘 다 기존 방법보다 모델의 파라미터 수를 현저히 감소시킴을 확인했고, HBIC가 BIC에 비해 더 적은 수의 파라미터를 사용해도 비슷한 인식률을 얻을 수 있었다.