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최적화 하이퍼 파라미터의 XGBoost 학습자 기반 배깅 모델을 활용한 태양광 출력 예측
최성현(Sung-hyeon Choi),허진(Jin Hur) 대한전기학회 2020 전기학회논문지 Vol.69 No.7
As the world is aware of the problem of greenhouse gas emissions, the trend of generating energy source has been changing from conventional fossil fuels to sustainable energy such as solar and wind. In order to reduce greenhouse gas emissions, the ratio of renewable energy sources should be increased. However, renewable energy sources highly depend on weather conditions and it has intermittent generation characteristics, thus embedding uncertainty and variability. As a result, it can cause variability and uncertainty in the power system, and that is why it is essential to have accurate forecasting technology of renewable energy to address this problem. We proposed a bagging model which is using an ensemble model as a base learner and what we set for the base learner is a XGBoost. Results showed that ensemble learner-based bagging models averagely have lower error compared to the bagging model using single model learner. Through the use of accurate forecasting technology, we will be able to reduce uncertainties in the power system and expect improved system reliability.
발효 콩의 NF-κB 활성 억제를 통한 cyclooxgenase-2 활성과 prostaglandin E₂ 생성 억제
Hye Hyeon Lee(이혜현),Cheol Park(박철),Min Jeong Kim(김민정),Min Jeong Seo(서민정),Sung-Hyun Choi(최성현),Yong Kee Jeong(정영기),Yung Hyun Choi(최영현) 한국생명과학회 2010 생명과학회지 Vol.20 No.3
본 연구에서는 콩 발효 산물 추출물의 항염증 효능에 관한 기초 자료를 제시하기 위하여 PMA에 의해 유도되는 COX-2의 발현 및 PGE₂의 생성 증가에 미치는 이들 추출물의 영향을 조사하였다. 본 연구에서 조사된 3가지 콩 발효 산물은 PMA에 의한 COX-2의 발현 증가를 매우 유의적으로 차단하였으며, 이는 PGE₂의 생성 억제와 연관성이 있었다. 아울러 PMA에 의한 NF-κB 활성 증가 또한 콩 발효 산물들에 의하여 유의적으로 억제되었다. 이러한 결과들은 콩 발효 산물에 의한 NF-κB 활성의 억제가 COX-2의 발현을 저하시켰으며, 이로 인한 PGE₂의 생성이 억제된 것으로 추정되어진다. 이러한 콩 발효 산물의 항염증 효과는 대두 추출물보다 아가콩 추출물에서 더욱 효과가 높게 나타났으며, 이는 향후 아가콩 추출물은 염증성 질환 예방/치료를 위한 적용 가능성이 매우 우수함을 제시하여 주는 결과이다. Cyclooxygenase (COX)-2 is generally known as an inducible enzyme, and it produces arachidonic acid to prostaglandin E2 (PGE₂), which has been demonstrated to play a critical role in inflammation. In the present study, we investigated the effects of the extracts of fermented beans including soybean (FS), black agabean (FBA) and yellow agabean (FYA), on the expression of COXs and production of PGE2 in U937 human promonocytic cells. Treatment of phorbol 12-myristate 13-acetate (PMA) significantly induced pro-inflammatory mediators such as COX-2 expression and PGE₂ production, whereas the levels of COX-1 remained unchanged. However, pre-treatment with FS, FBA and FYA significantly decreased PMA-induced COX-2 protein as well as mRNA, which is associated with inhibition of PGE₂ production. Moreover, FS, FBA and FYA markedly prevented the increase of nuclear translocation of nuclear factor kappa B (NF-κB) p65 by PMA. Our data indicate that the extracts of fermented beans exhibits anti-inflammatory properties by suppressing the transcription of pro-inflammatory cytokine genes through the NF-κB signaling pathway.
Effects of RetroMTA on osteoblastic differentiation in MC3T3-E1 cells
Hyo-Il Lee(이효일),Sung-Hyeon Choi(최성현),Ji-Hyun Jang(장지현),Hoon-Sang Chang(장훈상),Yun-Chan Hwang(황윤찬),In-Nam Hwang(황인남),Bin-Na Lee(이빈나),Won-Mann Oh(오원만) 대한치과재료학회 2018 대한치과재료학회지 Vol.45 No.2
Mineral trioxide aggregate (MTA) provides a very good sealing, acceptable biocompatibility, dentin bridge formation and osteo-inductive effect. However, MTA has a few drawbacks. RetroMTA including calcium-zirconia complex has been developed to overcome drawbacks of MTA, especially long setting time and difficult handling characteristics. Therefore, the aim of this study was to evaluate the effects of RetroMTA on biocompatibility, osteogenic differentiation and mineralization in MC3T3-E1 cells compared with conventional MTA. Cytotoxicity was assessed by WST-1 assay. The gene expression of osteogenic markers was detected by real-time PCR. ALP activity and mineralization behavior were evaluated using ALP and alizarin red staining. There was no statistically significant difference between ProRoot MTA and RetroMTA with material extracts at dilutions of 1/4, 1/10 and 1/50 in cell viability assay. Expression of osteogenic markers in both ProRoot MTA and RetroMTA groups was significantly higher than in control group. In the mineralization assay, RetroMTA showed significantly higher formation of mineralized nodules than in control. In conclusion, RetroMTA promotes osteogenic differentiation and potential mineralization. It appears to be a potential alternative to ProRoot MTA as a root-end filling material.
Effects of various root canal sealers on tooth discoloration and internal bleaching
Yi-San Kim(김이산),Sung-Hyeon Choi(최성현),Kyeong-Eun Youn(윤경은),Ji-Hyun Jang(장지현),Hoon-Sang Chang(장훈상),Yun-Chan Hwang(황윤찬),In-Nam Hwang(황인남),Won-Mann Oh(오원만),Bin-Na Lee(이빈나) 대한치과재료학회 2019 대한치과재료학회지 Vol.46 No.1
There are several causes of tooth discoloration following root canal treatment. In this study, we evaluated the effects of sealers on tooth discoloration and internal bleaching. Twenty-four teeth were divided into 4 groups: control group, AH plus, Endosequece BC, and MTA fillapex group. Root canal filling was performed using each sealer conventionally and non-vital bleaching was performed with sodium perborate. The L, a, and b values were measured using Vita easyshade. Tooth discoloration after root canal treatment occurs irrespective of the type of sealers and may cause discoloration with only gutta-percha cone. The effect of non-vital bleaching following the use of calcium silicate-based sealers such as Endosequece BC and MTA fillapex was higher than that of AH plus. Therefore, it needs careful use of sealers in endodontics and calcium silicate-based sealers have advantages of bleaching in case of discolored tooth.