• Korean Journal of Environment and Ecology
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• v.25 no.3
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• pp.389-403
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• 2011

Studies on effects of human action on the destruction of ecosystems and changes in biodiversity are being processed actively from the view point of landscape ecology. This study investigated present distribution status of the naturalization plant by disturbance of natural ecosystem which could be seen on 35 rural villages in Korea. The study made a landuse map on the study area then quantified the landscape ecologic characteristic using landscape index based on this landuse map. Correlation between landscape index on the study area and distribution characteristic of naturalization plant was analyzed. The landscape index was calculated by FRAGSTATS, a spatial analysis program, and naturalization index and urbanization index were used in the distribution characteristic of naturalization plant. As a result, naturalization index and patch density, naturalization index and edge density, naturalization index and area-weighted mean shape index were shown as having positive correlation, and naturalization and core area percentage of landscape, naturalization index and mean core area were displayed as having negative correlation.

• The Korean Journal of Applied Statistics
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• v.17 no.3
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• pp.489-498
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• 2004

In this paper, a new form of linear models referred to as generalized weighted linear models is proposed. The proposed models assume that the relationship between the response variable and explanatory variables can be modelled by a distribution function of the response mean and a weighted linear combination of distribution functions of covariates. This form addresses a structural problem of the link function in the generalized linear models in which the parameter space may not be consistent with the space derived from linear predictors. The maximum likelihood estimation with Lagrange's undetermined multipliers is used to estimate the parameters and resampling method is applied to compute confidence intervals and to test hypotheses.

• Journal of Korea Water Resources Association
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• v.49 no.6
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• pp.495-507
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• 2016

This study aims at hydrologically demonstrating the universality of power law distribution by analyzing runoff aggregation structures of river basins. Power law distribution is fitted to cumulative drainage area of basins of interest by maximum likelihood, which results in the power law exponents. And then those exponents are assessed in terms of the shape of catchment plan-form. As a main result all of the basins in this study have similar distributions of catchment area. The exponents from this study tend to be higher than the ones from previous researches reflecting self-similar property of the catchment plan-forms of interest. Further study is required about the universality of power law distribution by means of the more realistic flow routing scheme within the framework of DEM.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.981-981
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• 2012

최근 지구환경 변화에 따른 기후변화의 영향으로 자연재해의 형태는 점차 대형화, 다양화되고 있으며 극치사상의 발생 빈도가 계속해서 증가하고 있는 추세이다. 특히 도시하천의 경우 인구와 재산이 밀집해 있어 기후변화에 따른 홍수위험 및 취약성이 클 것으로 사료된다. 본 연구에서는 기후 변화에 따른 홍수위험 및 취약성 분석을 위하여 위험도 기반 불확실성을 다루는 수단으로 UQR-MCS (Upper Quartile Range-Monte Carlo Simulation)을 적용하였으며, 다양한 형태의 확률 분포로부터 특정변량(variable)의 확률분포 Quartile을 모의하였다. 또한 기후변화에 따른 도시하천의 홍수위험 및 취약성 평가를 위하여 도시하천에 적합한 홍수위험 및 취약성평가 지수(FVI: flood vulnerability index)를 산정하였으며, 홍수취약성지수는 기후변화(Climate change)와 도시화(Urbanization), 제방월류위험(Overtopping risk) 및 홍수범람 면적(Flood area) 등의 지표를 사용하였다. 각각의 지표는 엔트로피(Entropy) 기법을 적용하여 가중치를 부여하였으며, 표준화과정을 통한 일반화된 지표 값을 산정하였다. 우이천 유역의 기후변화에 따른 홍수위험 및 취약성 지표값은 KMA RCM A1B 시나리오자료를 바탕으로 추정한 미래 확률강수량과 각 인자별 재현기간에 따른 수문변량의 변화를 통하여 산정하였다. 본 연구의 결과는 향후 도시하천의 기후변화에 따른 홍수위험도분석 및 취약성 평가, 극치 수문사상에 대한 신뢰성 있는 분석과 더불어 예상치 못할 이상홍수에 대비한 하천방재 연구에 도움이 되리라 사료된다.

• The Korean Journal of Financial Management
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• v.21 no.2
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• pp.211-233
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• 2004

This purpose of paper is to propose a European option pricing formula when the rate of return follows the leptokurtic distribution instead of normal. This distribution explains well the volatility smile and furthermore the option prices calculated under the leptokurtic distribution are shown to be closer to the market prices than those of Black-Scholes model. We make an estimation of the implied volatility and kurtosis to verify the fitness of the pricing formula that we propose here.

• The Korean Journal of Applied Statistics
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• v.4 no.2
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• pp.157-170
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• 1991

This article is concerned with the goodness - of - fit test for exponentiality when both the scale and location parameters are unknown. A test procedure based on the $L_1$-norm of discrepancy between the cumulative distribution function and the empirical distribution function is proposed, and the critical values of the test statistic are obtained by Monte Carlo simulations. Also the null distributions of the proposed test statistic are presented for small sample sizes. The power of tests under certain alternative distributions is investigated to compare the proposed test statistic with the well-known EDF test statistics. Our Monte Carlo power studies reveal that the proposed test statistic has good power properties, for moderate-to-large sample sizes, in comparison to other statistics although it is a conservative test.

• The Korean Journal of Applied Statistics
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• v.8 no.1
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• pp.151-157
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• 1995

The method for detecting the best treatment is considered by means of hypothesis testing in the exponential case. The likelihood ratio test for a given hypothesis is derived to control the error probability, and the minimum powers in the interested regions are calculated to design the sampling plan.

• The Journal of Engineering Geology
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• v.20 no.4
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• pp.391-399
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• 2010

We performed a hydraulic analysis based on the wetness index of talus slopes in Jungsun, Gangwon province. We estimated the relation between the degree of development of the temporary water system, and talus topography and distribution. We also assessed the distribution of talus based on a map of the wetness index. We divided areas of tallus into stable and unstable types, and estimated the size, distribution and shape-preferred orientation of clasts. We performed numerical simulations of rockfall events to assess the optimum location of rockfall barriers upon talus slopes.

• Journal of the Korean Geotechnical Society
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• v.24 no.1
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• pp.119-130
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• 2008

Uncertainties in physical and engineering parameters for the design of shallow foundations arise from various aspects such as inherent variability and measurement error. This paper aims at investigating and reducing uncertainty from deterministic method by using the reliability-based design of shallow foundations accounting for the variation of various design parameters. A probability distribution type and statistics of random variables such as unit weight, cohesion, infernal friction angle and Young's modulus in geotechnical engineering are suggested to calculate the ultimate bearing capacities and immediate settlements of foundations. Reliability index and probability of failure are estimated based on the distribution types of random variables. Widths of foundation are calculated at target reliability index and probability of failure. It is found that application and analysis of the best-fit distribution type for each random variables are more effective than adoption of the normal distribution type in optimizing the reliability-based design of shallow foundations.

• Journal for History of Mathematics
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• v.9 no.2
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• pp.15-21
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• 1996

적률법(method of moment)이란 변수 X의 멱승에대한 기대치를 이용하여 분포의 성질을 알아보는 방법이다. 여기서 적률법이 이용되어진 역사적 배경을 소개하고, 3차 적률들의 선형적 성질을 비교하였다. 먼저, Kagan이 입증한 표본평균에 관한 3차 표본적률의 선형적 성질과 Bayesian 경우에 3차 사후적률(posterior moment)과 사후평균(posterior)의 선형성을 소개하였다. 그리고, 자연지수족(natural exponential family)아래서도 표본평균에 관한 3차 표본적률의 선형성을 알아보기 위해 단순함수(simple function)의 형태로 유도하였으며, 정규분포인 경우에 적용시켜 보았다.