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RISS 인기검색어
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- 저자 : Jiu Oh (검색결과 4 건)
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Forecasting with a combined model of ETS and ARIMA
Jiu Oh,Byeongchan Seong 한국통계학회 2024 Communications for statistical applications and me Vol.31 No.1
This paper considers a combined model of exponential smoothing (ETS) and autoregressive integrated moving average (ARIMA) models that are commonly used to forecast time series data. The combined model is constructed through an innovational state space model based on the level variable instead of the dierenced variable, and the identifiability of the model is investigated. We consider the maximum likelihood estimation for the model parameters and suggest the model selection steps. The forecasting performance of the model is evaluated by two real time series data. We consider the three competing models; ETS, ARIMA and the trigonometric Box-Cox autoregressive and moving average trend seasonal (TBATS) models, and compare and evaluate their root mean squared errors and mean absolute percentage errors for accuracy. The results show that the combined model outperforms the competing models.
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Development of Bibim Naengmyeon Sauce added with Watermelon Powder replacing sugar
Jiu Jin,Seiyoung Ahn,Jieun Oh,Chul Jin Kim,Mi Sook Cho 한국식품영양과학회 2021 한국식품영양과학회 학술대회발표집 Vol.2021 No.10
This study was conducted to investigate the possibility of watermelon as a natural sweetener on sauce. Watermelon powder was produced by drying whole watermelon including seed and rind containing rich Lycopene, Citrulline. The advantage of using watermelon powder is nutritional value instead of sugar, economical value as well. Bibimnaengmyeon sauces were prepared with 25-100% watermelon powder instead of sugar and analyzed with the control for quality characteristics and acceptance test. Moisture contents, pH, color, viscosity, salinity increased(p<0.001) while sugar contents decreased(p<0.001) as watermelon powder content increased. The WP50 sample that 50% of watermelon powder replacing sugar in the acceptance test showed a high result(p<0.01). The overall result indicates that the replacing 50% of sugar to Bibimnaemyeon sauce is optimal. This study is expected to contribute positive effect on surplus watermelom rendering to resources as natural sweetener. This work was supported by ‘Development of fresh HMR and its generic technology using local agricultural produce (Project No. PJ015281042021)’ from Rural Development Administration, Republic of Korea
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오지우,성병찬,Oh, Jiu,Seong, Byeongchan 한국통계학회 2022 응용통계연구 Vol.35 No.5
본 논문에서는 R에서 시계열 자료 예측을 위한 자동화 함수에 대하여 고찰하고 그 예측 성능을 비교합니다. 대표적인 시계열 예측 방법인 지수 평활 모형과 ARIMA (autoregressive integrated moving average) 모형을 대상으로 하였으며, 이들의 모형화 및 예측 자동화를 가능하게 하는 R의 4가지 자동화 함수인 forecast::ets(), forecast::auto.arima(), smooth::es()와 smooth::auto.ssarima()를 대상으로 하였습니다. 이들의 예측 성능을 비교하기 위하여 3,003가지의 시계열로 구성되어 있는 M3-Competition자료와 3가지의 정확성 척도를 사용하였습니다. 4가지 자동화 함수는 모형화의 다양성 및 편리성, 예측 정확도 및 실행 시간 등에서 각자 장단점이 있음을 확인하였습니다. In this paper, we investigate automatic functions for time series forecasting in R system and compare their performances. For the exponential smoothing models and ARIMA (autoregressive integrated moving average) models, we focus on the representative time series forecasting functions in R: forecast::ets(), forecast::auto.arima(), smooth::es() and smooth::auto.ssarima(). In order to compare their forecast performances, we use M3-Competiti on data consisting of 3,003 time series and adopt 3 accuracy measures. It is confirmed that each of the four automatic forecasting functions has strengths and weaknesses in the flexibility and convenience for time series modeling, forecasting accuracy, and execution time.
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Huang, Xing-Jiu,Li, Yue,Im, Hyung-Soon,Yarimaga, Oktay,Kim, Ju-Hyun,Jang, Doon-Yoon,Cho, Sung-Oh,Cai, Wei-Ping,Choi, Yang-Kyu IOP Pub 2006 Nanotechnology Vol.17 No.12
<P>Large-scale morphology-controlled SWCNT/polymeric microsphere arrays can be obtained by a wet chemical self-assembly technique. The loading of SWCNTs, the length of SWCNTs, and the size and nature of polymeric microspheres can easily be controlled. Similar results can also be reached using this method for MWCNTs. In both types of CNTs, they form an interesting interactive ‘net’ structure on spheres and sphere joints. The SWCNT/PS-modified Au electrode was used for detection of uric acid by cyclic voltammetry and single-potential time-based techniques. The preliminary results show that the modified electrode presents good sensitivity and stability to uric acid. </P>
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