• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.294-297
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• 2004

Mean squared error (MSE) is an effective criterion to combine the mean and the standard deviation responses in dual response surface optimization. The bias and variance components of MSE need to be weighted properly in the given problem situation. This paper proposes a systematic method to determine the relative weights of bias and variance in accordance with a decision maker's prior and posterior preference structure.

• Genomics & Informatics
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• 제15권1호
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• pp.38-47
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• 2017

Research into new methods for identifying highly expressed genes in anonymous genome sequences has been going on for more than 15 years. We presented here an alternative approach based on modified score of relative codon usage bias to identify highly expressed genes in crenarchaeal genomes. The proposed algorithm relies exclusively on sequence features for identifying the highly expressed genes. In this study, a comparative analysis of predicted highly expressed genes in five crenarchaeal genomes was performed using the score of Modified Relative Codon Bias Strength (MRCBS) as a numerical estimator of gene expression level. We found a systematic strong correlation between Codon Adaptation Index and MRCBS. Additionally, MRCBS correlated well with other expression measures. Our study indicates that MRCBS can consistently capture the highly expressed genes.

• 한국측량학회지
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• 제37권2호
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• pp.55-62
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• 2019

The stereo geometry establishment based on the precise sensor modeling is prerequisite for accurate stereo data processing. Ground control points are generally required for the accurate sensor modeling though it is not possible over the area where the accessibility is limited or reference data is not available. For the areas, the relative orientation should be carried out to improve the geometric consistency between the stereo data though it does not improve the absolute positional accuracy. The relative orientation requires conjugate points that are well distributed over the entire image region. Therefore the automatic conjugate point extraction is required because the manual operation is labor-intensive. In this study, we applied the method consisting of the key point extraction, the search space minimization based on the epipolar line, and the rigorous outlier detection based on the RPCs (Rational Polynomial Coefficients) bias compensation modeling. We tested different parameters of window sizes for Kompsat-2 across track stereo data and analyzed the RPCs precision after the bias compensation for the cases whether the epipolar line information is used or not. The experimental results showed that matching outliers were inevitable for the different matching parameterization but they were successfully detected and removed with the rigorous method for sub-pixel level of stereo RPCs precision.

• Human Ecology Research
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• 제57권2호
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• pp.171-183
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• 2019

Convergence between technology and financial services is ubiquitous and widespread. Virtual banks represent an important aspect of financial markets that can generate value added for consumers and enhance the quality of financial services. This study explores the effect of innovation characteristics (relative advantage, compatibility, and perceived risk), consumer characteristics (status quo bias), and social mechanisms (network externality: complementarity, numbers of peers) on consumers' adoption intention and resistance to virtual banks. This study adopted an innovation resistance model with two dependent variables: adoption intention and resistance to virtual banks. An online self-administered survey was conducted and 532 or non-users of virtual banks aged 20 to 69 years old were analyzed. Frequency analysis, descriptive analysis, and hierarchical multiple regression indicated that status quo bias, relative advantage, perceived risk, complementarity, and number of peers insignificantly influence the adoption intention regarding virtual banks. Furthermore, status quo bias, relative advantage, perceived risk, and number of peers insignificantly influence the resistance to virtual banks. Female respondents have a lower adoption intention and higher resistance to virtual banks than male respondents. The findings suggest that the innovation resistance model can be useful in understanding consumers'adoption and resistance behavior as well as reveal that innovation characteristics, consumer characteristics, and social mechanism are important antecedent variables of the innovation adoption decision.

• Journal of the Korean Statistical Society
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• 제24권2호
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• pp.507-518
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• 1995

The ordinary least squares based estiamte $S^2$ of the disturbance variance is considered in the linear regression model when the disturbances follow the first-order moving-average process. It is shown that $S^2$ is weakly consistent estimate for the disturbance varaince without any restriction on the regressor matrix X. Also, simple exact bounds on the relative bias of $S^2$ are given in finite sample sizes.

• Communications for Statistical Applications and Methods
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• 제17권4호
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• pp.515-525
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• 2010

본 논문에서는 패널회귀모형에서 회귀계수의 일반최소제곱추정량과 가중최소제곱추정량의 설계기반 성질을 살펴보았다. 복합표본이 주어진 경우에 두 추정량의 설계편향을 구하여 가중최소제곱추정량의 설계편향의 크기가 더 작음을 보였다. 또한 한국복지패널 데이터를 대상으로 모의실험을 실시하여 다음의 결과를 얻었다. 첫째, 일반최소제곱추정치의 상대편향이 가중최소제곱추정치의 상대편향보다 약 2배 정도 크게 나타났고 일반최소제곱추정치의 편향비가 더 크게 나타났다. 그리고 표본수가 증가하면 일반최소제곱 추정치의 상대편향은 완만하게 줄어든 반면 가중최소제곱추정치의 상대편향은 급속도로 줄어들었다. 둘째, 표본수가 증가하면 일반초소제곱추정치와 가중최소제곱추정치의 분산과 평균제곱오차는 모두 줄어들였다. 그러나 평균제곱오차에서 차지하는 편향제곱의 비율은 표본수가 증가할 때 일반최소제곱추정치에서는 증가하는 반면 가중최소제곱추정치에서는 감소하는 경향이 나타났다. 마지막으로 거의 모든 경우에 일반최소제곱추정치의 분산이 가중최소제곱추정치의 분산보다 작게 나타났다. 그리고 많은 경우에 일반최소제곱추정치의 평균제곱오차가 가중최소제곱추정치의 평균제곱오차보다 작게 나타났다. 그러나 표본수가 증가할수록 일반최소제곱추정치의 평균제곱오차가 가중최소제곱추정치의 평균제곱오차보다 커지는 경우가 늘어났다.

• Journal of Electrical Engineering and Technology
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• 제7권4호
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• pp.626-635
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• 2012

Most of single frequency GPS receivers utilize low-quality crystal oscillators. If a lowquality crystal oscillator is utilized as the time reference of a GPS receiver, the receiver's clock bias grows very fast due to its inherent low precision and poor stability. To prevent the clock bias becoming too large, large clock jumps are intentionally injected to the clock bias and the time offset for clock steering purpose. The abrupt changes in the clock bias and the time offset, if not properly considered, induce serious accuracy degradation in relative differential positioning. To prevent the accuracy degradation, this paper proposes an efficient and systematic method to eliminate the undesirable clock jump effects. Experiment results based on real measurements verify the effectiveness of the propose method.

• 한국산업보건학회지
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• 제32권1호
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• pp.21-30
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• 2022

Objectives: The purpose of this study is to suggest an optimal method by comparing the analysis methods of work environment measurement datasets including left-censored data where one or more measurements are below the limit of detection (LOD). Methods: A computer program was used to generate left-censored datasets for various combinations of censoring rate (1% to 90%) and sample size (30 to 300). For the analysis of the censored data, the simple substitution method (LOD/2), β-substitution method, maximum likelihood estimation (MLE) method, Bayesian method, and regression on order statistics (ROS)were all compared. Each method was used to estimate four parameters of the log-normal distribution: (1) geometric mean (GM), (2) geometric standard deviation (GSD), (3) 95th percentile (X95), and (4) arithmetic mean (AM) for the censored dataset. The performance of each method was evaluated using relative bias and relative root mean squared error (rMSE). Results: In the case of the largest sample size (n=300), when the censoring rate was less than 40%, the relative bias and rMSE were small for all five methods. When the censoring rate was large (70%, 90%), the simple substitution method was inappropriate because the relative bias was the largest, regardless of the sample size. When the sample size was small and the censoring rate was large, the Bayesian method, the β-substitution method, and the MLE method showed the smallest relative bias. Conclusions: The accuracy and precision of all methods tended to increase as the sample size was larger and the censoring rate was smaller. The simple substitution method was inappropriate when the censoring rate was high, and the β-substitution method, MLE method, and Bayesian method can be widely applied.

• 한국음향학회지
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• 제23권5호
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• pp.383-389
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• 2004

본 논문에서는 훈련 및 인식 환경이 다른 상황에서 eigenvoice 기반 고속화자적응의 성능향상을 위하여 바이어스 보상을 적용한 eigenvoice 적응방식과 차원별 eigenvoice 모델 평균 가중합 방식을 제안하였다. PBW 452 DB를 사용한 어휘독립 단어인식 실험 결과에서 적은 양의 적응데이터를 사용했을 때 제안된 방식이 기존의 eigenvoice 방식에 비하여 많은 성능향상을 얻을 수 있었다. 적응단어 수를 1개에서 50개로 변경시키면서 바이어스 보상을 적용한 eigenvoice 적응방식을 사용한 경우 기존 eigenvoice 방식보다 단어 오인식률이 약 22∼30% 감소하였다. 또한 차원별 eigenvoice 모델 평균을 이용한 eigenvoice 적응방식에서는 1개의 단어를 적응데이터로 사용했을 경우에 기존 eigenvoice 방식보다 단어 오인식률이 최고 41%까지 감소하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.37-37
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• 2008

Hydrogenated nanocrystalline Si (nc-Si:H) thin films were prepared by plasma enhanced chemical vapor deposition (PECVD). The films were deposited with a radio frequency power of 100 W, while substrates were exposed to direct current (DC) biases in the range from 0 to -400 V. The effects of the DC bias on the formation of nanoscale Si crystallites in the films and on their optical characteristics were investigated. The size of the Si crystallites in the films ranges from ~ 1.9 to ~ 4.1 nm. The relative fraction of the crystallites in the films reached up ~ 56.5 % when the DC bias of -400 V was applied. Based on the variation in the structural, chemical, and optical features of the films with DC bias voltages, a model for the formation of nanostructures of the nc-Si:H films prepared by PECVD was suggested. This model can be utilized to understand the evolution in the size and relative fraction of the nanocrystallites as well as the amorphous matrix in the nc-Si:H films.