• 전기학회논문지P
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• 제67권4호
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• pp.183-190
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• 2018

Predicting accurate electricity prices is an important task in the electricity trading market. To address the electricity price forecasting problem, various approaches have been proposed so far and it is known that linear regression-based approaches are the best. However, the use of such linear regression-based methods is limited due to low accuracy and performance. In traditional linear regression methods, it is not practical to find a nonlinear regression model that explains the training data well. If the training data is complex (i.e., small-sized individual data and large-sized features), it is difficult to find the polynomial function with n terms as the model that fits to the training data. On the other hand, as a linear regression model approximating a nonlinear regression model is used, the accuracy of the model drops considerably because it does not accurately reflect the characteristics of the training data. To cope with this problem, we propose a new electricity price forecasting method that divides the entire dataset to multiple split datasets and find the best linear regression models, each of which is the optimal model in each dataset. Meanwhile, to improve the performance of the proposed method, we modify the proposed localized linear regression method in the map and reduce way that is a framework for parallel processing data stored in a Hadoop distributed file system. Our experimental results show that the proposed model outperforms the existing linear regression model. Specifically, the accuracy of the proposed method is improved by 45% and the performance is faster 5 times than the existing linear regression-based model.

• 생물환경조절학회지
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• 제4권2호
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• pp.125-130
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• 1995

동계 시설내 온도 및 광도가 고추의 생장에 미치는 영향을 알기 위하여 생장상내에서 인공적으로 온도 3수준(10, 20 및 3$0^{\circ}C$)과 광도 3수준(5, 15 및 25klux)을 7주간 조합 처리한 결과 나타난 생장반응은 다음과 같다. 1. 생장상내에서 고추 시묘의 초장, 엽면적 및 건물중의 생장은 3$0^{\circ}C$$\times$25klux 처리구에서 가장 양호했고, 각 온도에서도 광도의 증가에 따른 생장의 증가반응이 뚜렷하였다. 2. 처리후 7주째의 생장량을 multiple regression polynomial로 수식화한 결과 초장, 엽수, 엽면적, 경건물 및 지하부 건물중은 수식고정이 적합하였다. 3. 지상부 건물중에 대한 다중 회귀식을 광도와 온도로 편미분한 이론치를 이용하여 단위온도 증가에 대한 단위광도의 향상도와 단위광도 증가에 대한 단위온도 증가의 반응표면을 도식화한 결과 저온화에서의 광도증가는 지상부 건물중 증가반응의 향상도를 크게 높였으나, 광도 10k1ux이하나 온도가 2$0^{\circ}C$이상에서는 온도의 역할이 더 크게 나타났다. 단위광도 증가에 대한 온도반응의 증가에서도 동일한 경향으로 나타나 온도와 광도의 강한 상보성을 나타내었다.

• 한국도로학회논문집
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• 제20권1호
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• pp.87-95
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• 2018

PURPOSES : A geo-grid pavement, e.g., a stress-absorbing membrane interlayer (SAMI), can be applied to an asphalt-overlay method on the existing surface-pavement layer for pavement maintenance related to reflection cracking. Reflection cracking can occur when a crack in the existing surface layer influences the overlay pavement. It can reduce the pavement life cycle and adversely affect traffic safety. Moreover, a failed overlay can reduce the economic value. In this regard, the objective of this study is to evaluate the bonding properties between the rigid pavement and a SAMI by using the direct shear test and the pull-off test. The predicted fractural energy functions with the shear stress were determined from a numerical analysis of the moving average method and the polynomial regression method. METHODS : In this research, the shear and pull-off tests were performed to evaluate the properties of mixtures constructed using no interlayer, a tack-coat, and SAMI with fabric and without fabric. The lower mixture parts (describing the existing pavement) were mixed using the 25-40-8 joint cement-concrete standard. The overlay layer was constructed especially using polymer-modified stone mastic asphalt (SMA) pavement. It was composed of an SMA aggregate gradation and applied as the modified agent. The sixth polynomial regression equation and the general moving average method were utilized to estimate the interlayer shear strength. These numerical analysis methods were also used to determine the predictive models for estimating the fracture energy. RESULTS : From the direct shear test and the pull-off test results, the mixture bonded using the tack-coat (applied as the interlayer between the overlay layer and the jointed cement concrete) had the strongest shear resistance and bonding strength. In contrast, the SAMI pavement without fiber has a strong need for fractural energy at failure. CONCLUSIONS : The effects of site-reflection cracking can be determined using the same tests on cored specimens. Further, an empirical-mechanical finite-element method (FEM) must be done to understand the appropriate SAMI application. In this regard, the FEM application analy pavement-design analysis using thesis and bonding property tests using cored specimens from public roads will be conducted in further research.

• 대한토목학회논문집
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• 제29권2B호
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• pp.193-205
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• 2009

태풍은 열대태평양 지역에서 발생하여 북상하면서 우리나라에 영향을 끼치게 되며, 태풍이 우리나라를 지나면서 강풍과 호우를 통하여 자연재해를 유발시키게 된다. 따라서 본 연구에서는 태풍으로 인해 발생하는 호우 사상을 여러 통계적 기법을 통해 정량적으로 평가하였다. 첫 번째로 빈도해석을 통해 확률강우량과 태풍 확률강우량을 산정하여 비교하였다. 두 번째로 미공병단에서 개발한 EST 기법을 통해 태풍의 극치강우량을 평가하여 EST 확률강우량을 산정하였다. 마지막으로 비매개변수적 모의발생기법과 지역가중다항식을 결합하여 태풍에 의한 NL 확률강우량을 추정하였다. 분석결과에서 대상지점 중에서 강릉과 목포는 태풍의 영향을 다른 지점에 비해 많이 받으며, 서울과 인천은 태풍에 의한 호우의 영향이 미비한 것으로 나타났다. 또한, EST 확률강우량과 NL 확률강우량은 관측 자료를 이용하여 장기간의 모의를 통하여 quantile을 산정하므로 주요 수공구조물과 태풍의 영향이 큰 지역에서는 이를 검토할 필요성이 있으며, 태풍특성인자의 모의를 통하여 강우량을 평가하므로 지구온난화 등에 따른 기후변화의 영향에 대한 연구에 활용 할 수 있다.

• Fibers and Polymers
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• 제5권2호
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• pp.139-144
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• 2004

The orthotropic theory is applied for the nonwoven fabrics that have a preferred orientation direction, the case if the structure is not isotropic. The polynomial regression analysis is employed to allow the attainment of more statistically meaningful information. A functional form based on the transformation rule is developed for the orthotropic approach. The predictions thus obtained are seen to be in excellent agreements with experimental data and the resulting compliances exhibit meaningful relationships for the processing conditions. The compatibility of the compliances from tensile and shear analyses has been explored prior to a practical application of the four compliances defining the in-plane strain-stress field.

• 대한전기학회논문지
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• 제39권6호
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• pp.607-615
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• 1990

In this paper, I propose the experimental models to classify the consonants in the Vowel-Consonant-Vowel (VCV) speech chain into four phonemic groups such as nasals, liquids, plosives and the others. To classify the fuzzy patterns like speech, it is necessary to analyze the distribution of acoustic feature of many training data. The classification rules are maximum 4 th order polynomial functions obtained by regression analysis, contributing collectively the result. The final result shows about 87% success rates with the data spoken by one man.

• Communications for Statistical Applications and Methods
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• 제16권6호
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• pp.1047-1054
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• 2009

Local smoothing jump detection procedure is a popular method for detecting jump locations and the performance of the jump detector heavily depends on the choice of the bandwidth. However, little work has been done on this issue. In this paper, we propose the bootstrap bandwidth selection method which can be used for any kernel-based or local polynomial-based jump detector. The proposed bandwidth selection method is fully data-adaptive and its performance is evaluated through a simulation study and a real data example.

• Journal of the Korean Statistical Society
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• 제7권2호
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• pp.109-119
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• 1978

When a response surface by a seconde order polynomial regression model, the stationary point is obtained by solving simultaneous linear equations. But the point is a function of random variables. We can find a confidence region for this point as Box and Hunter provided. However, the confidence region is often too large to be useful for the experiments, and it is necessary to augment additional design points in order to obtain a satisfactory confidence region for the stationary point. In this note, the author suggests a method how to augment design points "eficiently", and shows the change of the confidence region of the estimated stationary point in a response surface.e surface.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.993-996
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• 2005

High speed machining(HSM) technique is widely used in the appliance, automobile part and mold industries, which has many advantages such as good quality, low cost and rapid machining time. but it also has problems like tool break, smooth tool path, and so on. In particular, small size end mill is easy to break, so it must be changed before interrupting operation. Generally, the tool life of small size end mill is effected by the milling conditions whose evaluated parameters are spindle, feedrate, and width of cut. The experiments are carried out by full factorial design of experiments using and orthogonal array. This paper shows optimal combination and mathematical model for tool life, and the analysis of variance(ANOVA) is employed to analyze the main effects and the interactions of these milling parameters and the second-order polynomial regression model with three independent variables is estimated to predict tool life by multiple regression analysis.

• Asian-Australasian Journal of Animal Sciences
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• 제17권7호
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• pp.914-918
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• 2004

The random regression model methodology was applied into the estimation of genetic parameters for body weights in Chinese Simmental cattle to replace the traditional multiple trait models. The variance components were estimated using Gibbs sampling procedure on Bayesion theory. The data were extracted for Chinese Simmental cattle born during 1980 to 2000 from 6 national breeding farms, where records from 3 months to 36 months were only used in this study. A 3 orders Legendre polynomial was defined as the submodel to describe the general law of that body weight changing with months of age in population. The heritabilities of body weights from 3 months to 36 months varied between 0.31 and 0.48, where the heritabilities from 3 months to 12 months slightly decreased with months of age but ones from 13 months to 36 months increased with months of age. Specially, the heritabilities at eighteenth and twenty-fourth month of age were 0.33 and 0.36, respectively, which were slightly greater than 0.30 and 0.31 from multiple trait models. In addition, the genetic and phenotypic correlations between body weights at different month ages were also obtained using regression model.