• 한국습지학회지
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• 제20권2호
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• pp.105-115
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• 2018

수문기상자료의 빈도해석은 풍수해에 따른 대응 및 시설물의 설계기준에 있어 중요한 요소 중 하나이다. 일반적으로 수문기상자료에 대한 빈도해석의 경우 관측자료는 통계적으로 정상성을 가진다고 가정하고, 확률분포의 매개변수를 고려하는 매개변수적 방법을 적용하고 있다. 이러한, 매개변수적 빈도해석을 위해서는 신뢰성 있는 충분한 자료의 수집이 필요하지만, 강수량과 다르게 적설량의 경우 계절적 특성과 함께 최근에는 기후변화로 인한 적설량 관측일수 및 평균 최심신적설량이 감소하기 때문에 부족한 자료에 대한 문제점을 보완할 필요가 있다. 이에 본 연구에서는 매개변수 빈도해석 방법과 부족한 자료의 문제점을 보완할 수 있는 표본 재추출 기법인 Bootstrap방법과 SIR(Sampling Importance Resampling)알고리즘을 적용하여 적설량의 빈도해석을 실시하였다. 58개 기상관측소에 대해 재추출된 일 최대 최심신적설량 자료를 이용한 비매개변수적 빈도해석을 통해 확률적설량을 산정하고 이를 비교 분석하였다. 빈도별 확률적설량의 증감률을 검토한 결과 매개변수적 빈도해석과 비매개변수적 빈도해석에서 증감률을 나타내는 지점들이 대부분 일치하는 것으로 나타났다. 확률적설량은 관측 자료와 Bootstrap방법에서 -19.2%~3.9%, Bootstrap방법과 SIR알고리즘에서 -7.7%~137.8% 정도의 차이를 보였다. 표본 재추출 기법은 관측표본이 적은 적설량의 빈도해석 및 불확실성 범위의 제시가 가능함을 확인할 수 있었고, 이는 여름철 태풍과 같이 계절적 특성을 지닌 다른 자연재난의 해석에도 적용될 수 있을 것으로 판단된다.

• 한국임상수의학회지
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• 제27권1호
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• pp.66-70
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• 2010

Reference interval is critical for interpreting laboratory results, monitoring response to therapy and predicting the prognosis of the patients in clinical settings. The aim of the present study was to update established reference intervals for routine hematologic and serum chemistry values for a population of clinically healthy dogs (range, 1-8 years) seen in an animal hospital. Blood was obtained by venipuncture while animals were physically restrained, and samples were analyzed for 9 chemistries on MS9-5H (Melot Schloesing Lab, France) and 6 hematology on Vet Test 8008 (IDEXX, USA). Data from 105 dogs (52 males and 53 females) for hematology and 113 dogs (37 males and 76 females) for chemistry were used to determine reference intervals using the parametric, nonparametric and bootstrap methods. Prior to analysis, all parameters were tested for normal distribution using Anderson-Darling criterion. Of the 9 biochemical analytes, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, creatinine, total protein, and glucose concentrations did not fit normal distribution for both original and transformed data. All but eosinophil count satisfied normal distribution for either original or transformed data. Parametric method can be used for original cholesterol concentrations, RBC, WBC, and neutrophil counts. This technique can also be used for power-transformed values of blood urea nitrogen concentrations and for logarithm of lymphocyte and monocyte counts. Non-parametric or bootstrap method was the preferred choice for the remaining 7 biochemical parameters and eosinophil count as they did not follow normal distributions. All three statistical techniques performed in similar reference intervals. When establishing reference intervals for clinical laboratory data, it is essential to assess the distribution of the original data to increase the accuracy of the interval, and non-parametric or bootstrap methods are of alternative for the data that do not fit normal distribution.

• Structural Engineering and Mechanics
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• 제76권5호
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• pp.631-641
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• 2020

In the present work, an approach for the multiple time probabilistic characterization of the response of linear structural systems subjected to random non-Gaussian processes is presented. Its fundamental property is working directly on the multiple time probability density functions of the actions and of the response. This avoids of passing through the evaluation of the response statistical moments at multiple time or correlations, reducing the computational effort in a consistent measure. This approach is the extension to the multiple time case of a previously published dynamic Probability Transformation Method (PTM) working on a single evolution of the response statistics. The application to some simple examples has revealed the efficiency of the method, both in terms of computational effort and in terms of accuracy.

• 한국물환경학회지
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• 제20권1호
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• pp.63-71
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• 2004

The long-tenn trend analyses of water qualities were performed for 49 monitoring stations located in Nakdong River. Water quality parameters used in this study are the monthly data of BOD(Biological Oxygen Demand), TN(Total Nitrogen) and TP(Total Phosphorus) measured from 1990 to 1999. The long-tenn trends were analyzed by Seasonal Mann-Kendall Test and Locally WEighted Scatter plot Smoother(LOWESS). Nakdong river was divided into four subbasins, including upstream watershed, midstream watershed, western downstream watershed and eastern downstream watershed. The results of Seasonal Mann-Kendall Test indicated that there would be no trends of BOD in upstream watershed, western and eastern downstream watershed. Trends of BOD were downward in midstream watershed. For TN and TP, there were upward trends in all of watersheds. But LOWESS curves suggested that BOD, TN and TP concentrations generally increased between 1990 and 1996, then resumed decreasing.

• Korean Journal of Acupuncture
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• 제30권1호
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• pp.1-8
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• 2013

Objectives : The purpose of the present study was to examine statistical methods used in articles published on the Korean Journal of Acupuncture from 2007 through 2012. Methods : Statistical methods and statistical packages used in original articles applied with descriptive statistics or inferential statistics were organized. Results : Out of a total of 195 original articles, 18 articles used descriptive statistics only and 177 articles used inferential statistics. 142 articles used 12 types of statistical packages. SPSS was used most at 97 times(63.4%). The number of descriptive statistical methods used was a total of 417 and among them 193 were presented as tables(46.3%) and 224 were presented as graphs(53.7%). The number of inferential statistics applied was a total of 256 and analysis of variance was used most at 90 times(35.2%). The number of parametric statistical methods used was a total of 170(75.6%) and that of nonparametric statistical methods used was a total of 55(24.4%). Analysis of variance and two sample t-test were most employed in both clinical and non-clinical research. The number of multiple comparison methods applied was a total of 67 and the number of Scheffe methods among them was most at 26 times(37.7%). Conclusions : In the present study, statistical methods used in the journal over the last six years were examined. The result of this study is considered to be a basic material to be referred to when evaluating the quality of the medical journal.

• 응용통계연구
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• 제30권4호
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• pp.567-578
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• 2017

일반적으로 그룹화된 다변량자료는 다변량 분산분석(multivariate analysis of variance; MANOVA)을 사용하여 그룹 간 차이를 검정할 수 있다. 그러나 만약 다변량 분산분석의 기본적인 가정이 위배되면 이 방법은 적절하지 못하다. 이 경우 다양한 거리로부터 그룹화된 비유사성을 계산한 후 다차원척도법(multidimensional scaling; MDS), 거리분석(analysis of distance; AOD) 그리고 비모수적 기법인 순열검정(permutation test)을 적용하여 문제를 해결할 수 있다. 다차원척도법은 비유사성으로부터 개체들의 좌표를 계산해주며 거리분석은 이 좌표를 활용하여 그룹구조를 파악하는데 유용하다. 특히 비유사성의 측도로 유클리드 거리를 사용하면 거리분석은 다변량 분산분석과 수리적으로 매우 밀접한 연관관계를 맺는다. 따라서 본 연구에서는 그룹화된 비유사성에 다차원척도법과 거리분석을 적용하여 그룹 내와 그룹 간의 구조를 파악하고 순열검정을 위한 새로운 검정통계량을 제안하려 한다. 덧붙여 유클리드 거리를 활용한 비유사성을 통해 거리분석과 다변량 분산분석과의 수리적 연관성을 고찰하고자 한다.

• 한국안전학회지
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• 제32권5호
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• pp.115-121
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• 2017

This paper is to introduce the main modeling assumptions and data structures associated with right-censored data to describe the successful methodological ideas for analyzing such a field-failure-data when components operating in different environments. The Kaplan - Meier method is the most popular method used for survival analysis. Together with the log-rank test, it may provide us with an opportunity to estimate survival probabilities and to compare survival between groups. An important advantage of the Kaplan - Meier curve is that the method can take into account some types of censored data, particularly right-censoring. The above non-parametric method was used to verify the equality of parts life used in different environments. After that, we performed the life distribution analysis using the parametric method. We simulated data from three distributions: exponential, normal, and Weibull. This allowed us to compare the results of the estimates to the known true values and to quantify the reliability indices. Here we used the Akaike information criterion to find a suitable life time distribution. If the Akaike information criterion is the smallest, the best model of failure data is presented. In this paper, no-nparametrics and parametrics methods are analyzed using R program which is a popular statistical program.

• Structural Engineering and Mechanics
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• 제89권1호
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• pp.61-75
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• 2024

Strengthening of hollow structural sections using through-bolts is a cost-effective and straightforward approach. It's a versatile method that can be applied during both design and service phases, serving as a non-disruptive and budget-friendly retrofitting solution. Existing research on axially loaded hollow sections T-joints has demonstrated that this technique can amplify the joint strength by 50%, where single bolt could enhance the strength of the joint by 35%. However, there's a gap in understanding their use for K-joints. As the behavior of K-joints is more complex, and they are widely existent in structures, this study aims to bridge that gap by conducting comprehensive parametric study using finite element analysis. Numerical investigation was conducted to evaluate the effect of through bolts on K-joints focusing on using single through bolt to achieve most of the strengthening effect. A full-scale parametric model was developed to investigate the effect of various geometric parameters of the joint. This study concluded the existence of optimal bolt location to achieve the highest strength gain for the joint. Moreover, a rigorous statistical analysis was conducted on the data to propose design equations to predict optimal bolt location and the corresponding strength gain implementing the verified by finite element models.

• Computers and Concrete
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• 제32권4호
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• pp.425-438
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• 2023

In this article, the performance of steel fiber-reinforced concrete (SFRC) flat slabs was investigated numerically. The influence of flexural steel reinforcement, steel fiber content, concrete compressive strength, and slab thickness were discussed. The numerical model was developed using ATENA-Gid, user-friendly software for non-linear structural analysis for the evaluation and design of reinforced concrete elements. The numerical model was calibrated based on eight experimental tests selected from the literature to validate the actual behavior of steel fiber in the numerical analysis. Then, a parametric study of 144 specimens was generated and discussed the impact of various parameters on the punching shear strength, and statistical analysis was carried out. The results showed that slab thickness, steel fiber content, and concrete compressive strength positively affect the punching shear capacity. The fib Model Code 2010 for specimens without steel fibers and the model of Muttoni and Ruiz for SFRC specimens presented a good agreement with the results of this study.

• Communications for Statistical Applications and Methods
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• 제25권5호
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• pp.489-499
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• 2018

Jeonse is a unique property rental system in Korea in which a tenant pays a part of the price of a leased property as a fixed amount security deposit and gets back the entire deposit when the tenant moves out at the end of the tenancy. Jeonse deposit is very important in the Korean real estate market since it is directly related to the residential property sales price and it is a key indicator to predict future real estate market trend. Jeonse deposit data shows a skewed and heteroscedastic distribution and the commonly used mean regression model may be inappropriate for the analysis of Jeonse deposit data. In this paper, we apply a Bayesian quantile regression model to analyze Jeonse deposit data, which is non-parametric and does not require any distributional assumptions. Analysis results show that the quantile regression coefficients of most explanatory variables change dramatically for different quantiles. The regression coefficients of some variables have different signs for different quantiles, implying that even the same variable may affect the Jeonse deposit in the opposite direction depending on the amount of deposit.