• Journal of the Korean Data and Information Science Society
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• 제22권1호
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• pp.115-123
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• 2011

In this paper, we develop the noninformative priors for stress-strength reliability from the Pareto distributions. We develop the matching priors and the reference priors. It turns out that the second order matching prior does not match the alternative coverage probabilities, and is not a highest posterior density matching or a cumelative distribution function matching priors. Also we reveal that the one-at-a-time reference prior and Jeffreys' prior are the second order matching prior. We show that the proposed reference prior matches the target coverage probabilities in a frequentist sense through simulation study, and an example is given.

• 응용통계연구
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• 제11권2호
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• pp.363-376
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• 1998

선형 평활스플라인 추정은 경계 편의의 영향력을 제거 하기위해 수정된 것이다. 제시된 추정량은 적합된 값들과 관련있는 평활 모수 선택 기준의 계산을 개선시킨 O(n) 얄고리즘을 사용하여 효과적으로 계산할 수 있게 하였다. 추정량의 점근적 성질들이 균일 계획의 경우에 대하여 연구되었다. 이 경우에 경계수정 선형 평활스플라인들의 평균 제곱 오차의 성질들은 표준 이차 커널 평활들에 대한 평균제곱오차들과 점근적 특성으로 비교하였다.

• 한국보육지원학회지
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• 제13권4호
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• pp.53-73
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• 2017

Objective: This study intended to examine whether working mothers' job satisfaction has a moderating effect on the relationship between their parenting stress and second childbearing intention. Methods: The subjects were 202 working mothers in Seoul and Gyeonggi province, all of who had a single child under 36 months old. Working mothers' parenting stress, job satisfaction and second childbearing intention were assessed with questionnaires completed by the mothers. The data were analyzed using descriptive statistics, t-test, one-way ANOVA, Duncan test, Pearson's correlation, and moderator regression analysis. Results: First, a significant difference was revealed in the mothers' second childbearing intention depending on the type of their child's main caregiver. The second childbearing intention of the mothers who relied on babysitters to care for their children was lower than that of the mothers whose mothers, mother-in-laws or child care teachers cared for their children. Secondly, working mothers' parenting stress and job satisfaction significantly affected their second childbearing intention. Thirdly, the mothers' job satisfaction moderated the relationship between their parenting stress and second childbearing intention. Conclusion/Implications: It is necessary to provide working mothers with social support for enhancing their job satisfaction and alleviating their job stress, in order to increase their second childbearing intention.

• 응용통계연구
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• 제31권5호
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• pp.539-554
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• 2018

최근 등장하는 다양한 사물인터넷 기기 혹은 상황인식 기반의 인공지능에서는 사용자와 기기의 상호작용이 중요시 된다. 특히 인간을 대상으로 상황에 맞는 대응을 하기 위해서는 인간의 표정을 실시간으로 인식하여 빠르고 정확한 판단을 내리는 것이 필요하다. 따라서, 보다 빠르고 정확하게 표정을 인식하는 시스템을 구축하기 위해 얼굴 이미지 분석에 대한 많은 연구들이 선행되어 왔다. 본 연구에서는 웹사이트 Kaggle에서 제공한 48*48 8-bit grayscale 이미지 데이터셋을 사용하여 얼굴인식과 표정분류로 구분된 두 단계를 거치는 얼굴표정 자동 인식 시스템을 구축하였고, 이를 기존의 연구와 비교하여 자료 및 방법론의 특징을 고찰하였다. 분석 결과, Face landmark 정보에 주성분분석을 적용하여 단 30개의 주성분만으로도 빠르고 효율적인 예측모형을 얻을 수 있음이 밝혀졌다. LDA, Random forest, SVM, Bagging 중 SVM방법을 적용했을 때 가장 높은 정확도를 보이며, LDA방법을 적용하는 경우는 SVM 다음으로 높은 정확도를 보이며, 매우 빠르게 적합하고 예측하는 것이 가능하다.

• Journal of Communications and Networks
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• 제14권1호
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• pp.1-9
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• 2012

We consider a receiving node, located at the origin, and a Poisson point process (PPP) that models the locations of the desired transmitter as well as the interferers. Interference is known to be non-Gaussian in this scenario. The capacity bounds for additive non-Gaussian channels depend not only on the power of interference (i.e., up to second order statistics) but also on its entropy power which is influenced by higher order statistics as well. Therefore, a complete statistical characterization of interference is required to obtain the capacity bounds. While the statistics of sum of signal and interference is known in closed form, the statistics of interference highly depends on the location of the desired transmitter. In this paper, we show that there is a tradeoff between entropy power of interference on the one hand and signal and interference power on the other hand which have conflicting effects on the channel capacity. We obtain closed form results for the cumulants of the interference, when the desired transmitter node is an arbitrary neighbor of the receiver. We show that to find the cumulants, joint statistics of distances in the PPP will be required which we obtain in closed form. Using the cumulants, we approximate the interference entropy power and obtain bounds on the capacity of the channel between an arbitrary transmitter and the receiver. Our results provide insight and shed light on the capacity of links in a Poisson network. In particular, we show that, in a Poisson network, the closest hop is not necessarily the highest capacity link.

• 정보기술응용연구
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• 제1권
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• pp.173-211
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• 1999

The task of classification permeates all walks of life, from business and economics to science and public policy. In this context, nonlinear techniques from artificial intelligence have often proven to be more effective than the methods of classical statistics. The objective of knowledge discovery and data mining is to support decision making through the effective use of information. The automated approach to knowledge discovery is especially useful when dealing with large data sets or complex relationships. For many applications, automated software may find subtle patterns which escape the notice of manual analysis, or whose complexity exceeds the cognitive capabilities of humans. This paper explores the utility of a collaborative learning approach involving integrated models in the preprocessing and postprocessing stages. For instance, a genetic algorithm effects feature-weight optimization in a preprocessing module. Moreover, an inductive tree, artificial neural network (ANN), and k-nearest neighbor (kNN) techniques serve as postprocessing modules. More specifically, the postprocessors act as second0order classifiers which determine the best first-order classifier on a case-by-case basis. In addition to the second-order models, a voting scheme is investigated as a simple, but efficient, postprocessing model. The first-order models consist of statistical and machine learning models such as logistic regression (logit), multivariate discriminant analysis (MDA), ANN, and kNN. The genetic algorithm, inductive decision tree, and voting scheme act as kernel modules for collaborative learning. These ideas are explored against the background of a practical application relating to financial fraud management which exemplifies a binary classification problem.

• Journal of the Korean Data and Information Science Society
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• 제22권2호
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• pp.227-234
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• 2011

이 논문에서는 척도화 향상도에 근거한 처방 선택 방법들을 제안하였다. 이 연구는 Park과 Kim(2010)에 의해 사용된 향상도가 특정 범위에 국한되지 않아 얼마나 커야 (혹은 작아야) 큰 (혹은 작은) 값인지 알기 힘든 문제점을 극복하기 위해 제안되었다. 제안된 첫 번째 척도화 향상도는 향상도를 바로 척도화 시켜 0과 1사이의 값을 취하도록 하였으며, 두 번째 척도화 향상도는 향상도-1을 척도화 시켜 -1과 1사의의 값을 취하도록 하였다. 구체적으로 첫 번째 척도화는 향상도를 척도화만 시킨 형태이고, 두 번째 척도화는 향상도를 중심화와 동시에 척도화 시킨 형태이다. 이 척도화 향상도에 근거한 처방 선택 방법들을 응급실 급성 충수염 환자에 적용하여 향상도에 근거한 처방 선택 결과와 비교하였다.

• 응용통계연구
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• 제23권1호
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• pp.189-196
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• 2010

미국의 1970년 징병추출(draft lottery)은 유한 순서열 (1, 2, ..., k)의 물리적 임의화를 쉬운 일로 생각하였다가 사회적 물의가 빚어진 대표적인 사례이다. 본 소고는 숫자 1, 숫자 2, ... 등의 순서로 쌓인 k장의 카드 뭉치를 물리적으로 임의화하는 데 있어 반복 시행(repeated trial)의 역할을 밝힌다. 부수적으로 독립시행 수 n, 성공의 확률이 $\theta$인 이항분포 B(n, $\theta$)에서 성공 수가 짝수일 확률은 n이 커짐에 따라 0.5에 수렴하게 됨을 보인다.

• 한국자동차공학회논문집
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• 제7권5호
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• pp.268-277
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• 1999

Impulsive acoustic and vibration signals within gear are often induced by impacting of fault tooths in gear. Thus the detection of these impulses can be useful for fault diagnosis. Recently there is an increasing trend towards the use of higher order statistics for fault detection within mechanical systems based on the observation that impulsive signals then to increase the kurtosis values. We show that the fourth order Wigner Moment Spectrum, called the Wigner Trispectrum, has found superior detection performance to second order Wigner distribution for typical impulsive signals in a condition monitoring application. These methods are also applied to data sets measured within an industrial gear box.

• Journal of the Korean Statistical Society
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• 제20권2호
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• pp.118-138
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• 1991

Given a random sample of size N(unknown) with density f(x $\theta$), suppose that only n observations which lie outside a region R are recorded. On the basis of n observations, the Bayes estimators of $\theta$ and N are considered and their asymptotic expansions are developed to compare their second order asymptotic properties with those of the maximum likelihood estimators and the Bayes modal estimators. Corrections to bias and median bias of these estimators are made. An example is given to illustrate the results obtained.