• 한국지하수토양환경학회지:지하수토양환경
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• 제22권6호
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• pp.57-65
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• 2017

Six soil subsampling methods were evaluated with explosive compounds-contaminated soils to quantify the variance associated with each method. The methods include modified grab sampling, simplified ripple splitting, fractional shoveling, coning & quatering, degenerate fractional shoveling, and rolling & quatering. All the methods resulted in significantly lower CV (coefficient of variation) of 1~5%, compared to common grab sampling that gave 8~98% of CV, possibly due to the reduction of grouping and segregation errors described by Gy sampling theory. Among the methods, simplified ripple splitting tends to result in lower explosive compounds concentrations, while the rolling & quatering gave the opposite result. Fractional shoveling method showed the least variance and the highest reproducibility in the analysis.

• Communications for Statistical Applications and Methods
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• 제28권4호
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• pp.351-368
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• 2021

For a probabilistic model with positively skewed data, a lognormal distribution is one of the key distributions that play a critical role. Several lognormal models can be found in various areas, such as medical science, engineering, and finance. In this paper, we propose a new estimator for a lognormal mean and depict the performance of the proposed estimator in terms of the relative mean squared error (RMSE) compared with Shen's estimator (Shen et al., 2006), which is considered the best estimator among the existing methods. The proposed estimator includes a tuning parameter. By finding the optimal value of the tuning parameter, we can improve the average performance of the proposed estimator over the typical range of σ². The bias reduction of the proposed estimator tends to exceed the increased variance, and it results in a smaller RMSE than Shen's estimator. A numerical study reveals that the proposed estimator has performance comparable with Shen's estimator when σ² is small and exhibits a meaningful decrease in the RMSE under moderate and large σ² values.

• International journal of advanced smart convergence
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• 제7권4호
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• pp.40-49
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• 2018

We propose a more stable robust recognition algorithm which detects faces reliably even in cases where there are changes in lighting and angle of view, as well it satisfies efficiency in calculation and detection performance. We propose detects the face area alone after normalization through pre-processing and obtains a feature vector using (PCA). The feature vector is applied to LDA and using Euclidean distance of intra-class variance and inter class variance in the 2nd dimension, the final analysis and matching is performed. Experimental results show that the proposed method has a wider distribution when the input image is rotated $45^{\circ}$ left / right. We can improve the recognition rate by applying this feature value to a single algorithm and complex algorithm, and it is possible to recognize in real time because it does not require much calculation amount due to dimensional reduction.

• Nutrition Research and Practice
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• 제17권4호
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• pp.812-825
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• 2023

BACKGROUND/OBJECTIVES: This study investigated the importance and performance level of sodium reduction practices in school meal service by school nutrition teachers and dietitians, and compared them according to school level and placement of the school nutrition teacher. SUBJECTS/METHODS: An online survey was conducted with 608 nutrition teachers and dietitians in schools in the Republic of Korea from September 28 to November 12, 2021 (response rate: 57%). The questionnaire comprised 11 items related to sodium reduction practices (purchasing, food preparation and serving, and education). The importance and performance level of each item was rated on a 5-point scale. The mean differences were analyzed using t-tests or one-way analyses of variance and Duncan's post-hoc tests. An importance-performance analysis was performed on sodium reduction practices. RESULTS: Participating in sodium reduction education, sodium reduction education for cooks, and sodium reduction education for students were assessed to have high importance but low performance. Overall, the higher the school level, the lower was the importance level of sodium reduction practices. The performance in kindergartens and elementary schools was higher than that in middle and high schools. The importance in the purchasing category perceived by dietitians was lower as compared to nutrition teachers. In addition, the performance in the purchasing, food preparation and serving, and education categories perceived by dietitians was lower than those of nutrition teachers. CONCLUSION: Sodium reduction education for nutrition teachers and dietitians, cooks, and students should prioritize practicing sodium reduction in school meal service. Specific guidelines for managing sodium reduction at all stages-purchasing, food preparation, and serving-should also be developed. The results could be used as basic data to reduce the sodium content in school meals.

• 정보처리학회논문지C
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• 제15C권3호
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• pp.149-156
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• 2008

JPEG2000은 차세대 이미지 압축 포맷으로 JPEG에 비하여 우수한 압축률과 화질을 제공할 수 있다. JPEG2000 이미지를 커버 오브젝트로 사용하는 lazy-mode 스테가노그라피는 압축과정에서 발생하는 정보 손실에 의해 메시지가 손실되지 않도록 제안된 알고리즘으로 많은 양의 메시지 삽입이 가능하다. 그러나 이 방법은 메시지 삽입으로 인하여 코드블럭 노이즈 분산의 변화를 발생하게 되고, 이러한 특징을 기반으로 하는 Hilbert-Huang 변환 (HHT) 기반의 스테거낼리시스에 의하여 메시지 삽입여부가 탐지될 수 있다. 본 논문에서는 코드블럭 노이즈 분산의 변화를 예측하고, 이를 최소화하도록 메시지를 삽입하여 HHT 기반 스태거낼리시스에 의해 탐지되지 않는 새로운 JPEG2000 스테가노그라피 알고리즘을 제시한다. 코드블록 노이즈 분산의 변화를 예측하기 위하여 low precision code-block variance와 low precision code-block noise variance를 활용하였다. 또한 메시지 삽입 후의 높은 영상 화질을 유지하기 위하여 JPEG2000의 quality layer 정보를 활용하였다. 제안한 알고리즘의 성능을 보이기 위하여 2048장의 다양한 영상에 대하여 분석을 수행하였고, 이를 통하여 HHT 기반 스태거낼리시스 방법에 안전함을 증명하였다.

• 한국생활과학회지
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• 제17권5호
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• pp.963-973
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• 2008

Clothing pressure is closely connected with the degree of comfort of an athlete's tight-fitting garments. Therefore, the construction of sports garments is very important to the wearer's athletic performance. In this study, the fundamental relationship between the reduction rates of stretch fabrics and clothing pressure was explored with the aim of improving clothing comfort and obtaining a systematic pattern reduction for women's tight-fitting bodysuits. A women's bodysuit pattern was obtained by the draping method using a dressform. The basic pattern was divided into four parts and changed into reduced pattems according to the amount of fabric stretch determined by ASTM D2594. Clothing pressure was measured using an air-pack-type pressure sensor (model AMI 3037-2) at 20 locations (shoulder, 9 locations; bust, 5; and armhole, 6). Among the 15 garments tested, the mean pressure of the A1 bodysuit was 4.60 $gf/cm^2$, and that of the C5 bodysuit was 22.98 $gf/cm^2$. The mean pressures of the bodysuits with reduction rates of 10% and 20% were below 10 $gf/cm^2$, while those of suits with reduction rates of 30%,40%, and 50% (except C5) were below 20 $gf/cm^2$. The pressure at the shoulder was 9.50$\sim$32.24 $gf/cm^2$, which was higher than that at the bust (3.34$\sim$24.56 $gf/cm^2$) and the armhole (0.95$\sim$12.15 $gf/cm^2$). The mean pressures of the 15 bodysuits were divided into five groups using analysis of variance (ANOVA), and were found to be significantly different (p<0.001). Regression analysis afforded the following expression: mean pressure ($gf/cm^2$) = 1.607 + 0.369[reduction rate (%)].

• 한국통계학회:학술대회논문집
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• 한국통계학회 2000년도 추계학술발표회 논문집
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• pp.65-73
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• 2000

Kernel estimator is very popular in nonparametric density estimation. In this paper we propose an estimator which reduces the bias to the fourth power of the bandwidth, while the variance of the estimator increases only by at most moderate constant factor. The estimator is fully nonparametric in the sense of convex combination of three kernel estimators, and has good numerical properties.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1992년도 춘계공동학술대회 발표논문 및 초록집; 울산대학교, 울산; 01월 02일 May 1992
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• pp.371-380
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• 1992

본 논문에서는 어떤 공정이 일반적인 확률분포를 따른다는 가정하에, 시뮬레이션에 의한 CUSUM챠트의 ARL을 추정하는 방법에 관하여 기술하였다. 추정치에 대한 분산을 최소화하기 위하여 TOTAL HAZARD방법을 적용하였으며, 지수분포를 따르는 공정에 대하여 HAZARD 및 CYCLE추정치와 분산감소법을 적용하지 않았을 경우의 추정치와 비교분석하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
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• pp.648-651
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• 1986

Sometimes, there are conditions when rapid control of the hypertension needed such as malignant hypertension, and the preoperative pereparation of the hypertensive patient requiring emergency operation, etc. Using the adaptive control algorithm, the mean arterial pressure reduction is achived rapidly and safely in hypertensive rabbit. Among the adaptive control algorithms the pole assignment self tuning control algorithm is superial to the one step ahead minium variance control algorithm. The convergence time is less than 600 sec, and the standard deviation of experimental data are less than 4 mmHg.

• Journal of the Korean Statistical Society
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• 제11권1호
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• pp.59-68
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• 1982

We propose that, in order to control the inflation and general instability associated with the least squares estimates, we can use the ridge estimator $$ \hat{B}^* = (X'X+kI)^{-1}X'Y : k \leq 0$$ for the regression coefficients B in multivariate regression. Our hope is that by accepting some bias, we can achieve a larger reduction in variance. We show that such a k always exists and we derive the formula obtaining k in multivariate ridge regression.