• Earthquakes and Structures
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• 제13권4호
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• pp.397-407
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• 2017

With the growing demand for metallic dampers in engineering practice, it is urgent to establish a reasonable approach to evaluating the mechanical performance of metallic dampers under seismic excitations. This paper introduces an effective method for parameter identification of the modified Bouc-Wen model and its application to evaluating the fatigue performance of metallic dampers (MDs). The modified Bouc-Wen model which eliminates the redundant parameter is used to describe the hysteresis behavior of MDs. Relations between the parameters of the modified Bouc-Wen model and the mechanical performance parameters of MDs are studied first. A modified Genetic Algorithm using real-integer hybrid coding with relative fitness as well as adaptive crossover and mutation rates (called RFAGA) is then proposed to identify the parameters of the modified Bouc-Wen model. A reliable approach to evaluating the fatigue performance of the MDs with respect to the Chinese Code for Seismic Design of Buildings (GB 50011-2010) is finally proposed based on the research results. Experimental data are employed to demonstrate the process and verify the effectiveness of the proposed approach. It is shown that the RFAGA is able to converge quickly in the identification process, and the simulation curves based on the identification results fit well with the experimental hysteresis curves. Furthermore, the proposed approach is shown to be a useful tool for evaluating the fatigue performance of MDs with respect to the Chinese Code for Seismic Design of Buildings (GB 50011-2010).

• Journal of the Korean Statistical Society
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• 제14권2호
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• pp.76-86
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• 1985

Shewhart X-chart, which is most widely used in practice, is shown to be inappropriate for the cases where the process distribution is one-sided asymmetrical, and thus some nonparametric Shewhart type charts are developed instead. These schemes may be applied usefully when there is not enough information in determining the process distribution. The average run lengths are obtained to compare the efficiency of control charts for various shifts of the location parameter and for some typical one-sided asymmetrical distributions.

• Communications for Statistical Applications and Methods
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• 제6권1호
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• pp.25-32
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• 1999

A single outlier can influence on the least squares estimators and can invalidate analysis based on these estimators. The Cook's statistic has been introduced to measure influence of individual data point on parameter estimation and the quantile of the F distribution is recommended as a reference value. but in practice subjective judgement is applied in the choice of appropriate quantile. A simple reference value is introduced in this paper which is developed by approximating conditional quantities of Cook's measure. The performance of the proposed criterion is evaluated through analysis of real data set.

• 한국통계학회:학술대회논문집
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• 한국통계학회 2003년도 춘계 학술발표회 논문집
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• pp.109-114
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• 2003

The concept of dispersion is intrinsic to the theory and practice of statistics. A formulation of the concept of dispersion can be obtained by comparing the probability of intervals centered about a location parameter, which is peakedness ordering introduced first by Birnbaum (1948). We consider statistical inference concerning peakedness ordering between two arbitrary distributions. We propose nonparametric maximum likelihood estimator of two distributions under peakedness ordering and a likelihood ratio test for equality of dispersion in the sense of peakedness ordering.

• Journal of the Korean Statistical Society
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• 제33권3호
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• pp.303-312
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• 2004

The concept of dispersion is intrinsic to the theory and practice of statistics. A formulation of the concept of dispersion can be obtained by comparing the probability of intervals centered about a location parameter. This is the peakedness ordering introduced first by Birnbaum (1948). We consider statistical inference concerning peakedness ordering between two arbitrary distributions. We propose non parametric maximum likelihood estimators of two distributions under peakedness ordering and a likelihood ratio test for equality of dispersion in the sense of peakedness ordering.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• 제18권2호
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• pp.97-108
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• 2007

Multiple areas of development are affected in pervasive developmental disorders(PDD), and assessments of various aspects of behavior and development are essential for diagnosis. The object of this review is to provide the practical guidelines for the assessment of core features of PDD, including abnormalities in communication, social interaction, and repetitive and stereotyped behavior. It covers the issues of differential diagnosis within and outside the PDD category, standardized diagnostic tools, assessment of intellectual and language functions, and the early diagnosis of PDD in infancy. This guideline also stresses the process of medical and neurological evaluation for proper diagnosis of PDD.

• 지역사회간호학회지
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• 제18권4호
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• pp.583-592
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• 2007

Purpose: This study was performed to understand health perception, health practice, and depression of the elderly and to identify their depression level according to health perception and health practice. Method: The subjects were 463 elders who have lived in the Jeju Island and data were collected from June to August in 2005. Data were analyzed by SPSS 10.0. Result: The mean score of depression was 12.94 out of 30, and had a statistically significant correlation with educational level (F=2.943 p=.033), occupation (F=4.611. p=.010), and the number of chronic diseases (F=5.303. p=.001). When the cutoff of 18 points was applied based on Jung et al. (1997), the depression ratio was 12.4%, and when the cutoff parameter by Yesavage et al (1993) was applied, themoderate depression ratio was 74.8% and the severe depression ratio was 3.4%. In health recognition, consideration of usual health state had a significant correlation with depression (F=3.553 p=.007) but consideration of health state compared to the previous year wasn't. In health practice, sleeping was in a significant correlation with depression (F=3.574 p=.011), but smoking, alcohol drinking, exercise, and rest were not. Conclusion: Based on above results, we need further study on another sample group and the development, application, and verification of health management, education, and counseling programs for the elderly. Also, additional research should be made on significant factors of elderly depression.

• 물과 미래
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• 제27권4호
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• pp.85-94
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• 1994

본 연구에서는 국내에서 도시하천유역의 설계홍수량 산정을 위해 사용되고 있는 Clark 유역추적방법에서의 매개변수들의 민감도 분석을 실시하여, 각 매개변수가 도시소유역의 계획홍수량에 미치는 영향을 살펴보고자 하였다. 먼저 적용강우의 시간분포형태에 따른 영향을 살펴보기 위해 Huff 분포, Yen & Chow 분포 그리고 일본에서 사용되는 중앙집중형 강우분포를 단기간강우로 선정하였으며, 국내에서 가장 널리 사용되고 있는 강우분포인 Mononobe 24시간-강우분포를 선정하였다. 또한 유효강우량의 산정을 위해 사용되는 SCS 방법의 CN 값과 시간-면적 곡선의 작성을 위한 소유역 구분 방법의 영향도 검토하였다. 저류상수 K는 Clark 방법의 매개변수 중 계획홍수량에 가장 큰 영향을 주는 인자이므로, 본 연구에서는 K값이 계획홍수량에 미치는 영향을 분석하였고, 실측자료가 없는 유역에서는 K값 산정을 위해 사용될 수 있는 다중 회귀방정식을 제시하였다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 추계종합학술대회
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• pp.491-498
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• 2001

본 논문에서는 개방형 통신상에서 전송중인 데이터를 암호화시켜 정보의 노출을 방지하고 송신자가 인정한 수신자만이 이러한 정보를 받을 수 있도록 한 암호화 알고리즘을 제시한다. 암호화의 방법에는 크게 관용키 암호화 방법과 공개키 암호화 방법으로 나누는데 본 논문에서는 혼합형 암호화 방식의 개념을 이용했다. 이 알고리즘은 통신시간과 저장공간을 절약하기 위해 전송할 데이터를 압축한 다음 암호화시키게 되며, 암호화 key를 생성하기 위한 파라미터로서 키를 생성하게 하는 것이 특징이다. 파라미터는 키 값이 생성됨과 동시에 전송되고 매 26회마다 파라미터를 변경시켜 키를 재생성 시킨다. 암호화키의 구성요소인 random number 는 table 형태로 저장되는데 키가 40회마다 table을 재편성 key의 보안을 강화하였다. 이렇게 생성된 키와 원래 데이터는 연산과정을 거쳐 암호화가 이루어진다. 복호화는 전송된 파라미터를 조사해 복호화 키를 구한 다음 암호화 동작의 역순으로 수행한다. 본 논문에서 제시한 알고리즘을 구현 및 평가결과는 100KB 메시지 0.0152/sec 정도로 빠른 수행이 되었다.

• 응용통계연구
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• 제29권4호
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• pp.741-752
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• 2016

금융자산의 수익률 분포를 잘 설명할 수 있는 것으로 알려진 normal inverse Gaussian(NIG)분포는 모수의 조건에 의해 세 배의 초과첨도가 왜도 제곱의 5배보다 커야 하는데, 만약 관측된 초과첨도와 왜도의 관계가 이를 만족하지 못하거나 두 값이 매우 비슷하다면 모수를 안정적으로 추정하기 어렵게 된다. 이 논문에서 우리는 NIG분포의 모수추정에서 발생하는 이러한 문제점을 살펴보고 모의실험을 통해 이를 보정하는 방법을 찾아보았다. KOSPI, S&P500, FTSE와 HANG SENG의 실제 주가지수 자료에 적용하여 보정의 효과를 비교하고 VaR를 이용한 사후검증으로 보정된 추정방법의 성능을 평가해 보았다. 보정 방법을 이용하였을 때, 모수추정의 문제가 있던 구간을 포함한 모든 구간에서 안정적인 모수추정이 가능하였고 VaR를 통한 사후 검증에서도 분포의 성능이 떨어지지 않음을 확인하였다.