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TabNet 기반의 반도체 재공재고 수준의 조기예측과 해석
방성진,고해지,이상민 한국정보과학회 2022 정보과학회논문지 Vol.49 No.6
In this study, we propose using TabNet, a deep learning model effective for tabular dataset, to predict the average and maximum levels of WIP (work-in-process) in semiconductor plant. The WIP estimation is an essential problem for decision-making to expand factory infrastructure facilities, because the under- or over-estimation of WIP causes production inefficiency and unnecessary costs, resulting in production loss. To resolve this problem, we here present a framework, which accurately predicts the average and maximum level of WIP and analyzes the main causes of changes in the level of WIP. We conducted experimental studies to show the outperformance of TabNet with competitive machine-learning methods. Experimental results show that the proposed approach obtained R2 0.86 and 0.95 for the average level of WIP and the maximum level of WIP, respectively. Furthermore, a model-agnostic interpretation method, Shapley additive explanations, was used to identify the significant variables for predictions. 본 연구는 정형 데이터에 효과적인 딥러닝 모델인 TabNet을 활용하여 반도체 공장 내 재공재고(Work-in-process)의 평균 및 최대 수준을 조기 예측한다. 생산공정 중에 있는 재공재고의 추정 문제는 공장 인프라 설비의 확장 계획과 직결되어, 과소/과대 예측할 경우 생산활동을 제약하거나 불필요한 비용을 가중시킨다. 이러한 문제해결을 위해 본 연구에서는 재공재고의 평균과 최대 수준을 정확히 예측함과 동시에 재공재고 수준의 변화의 주요원인 분석용 해석 프레임워크를 제공한다. 특히, 정확도 높은 조기예측을 위해 TabNet 활용을 제안하였으며 다수의 기계학습 모델과 비교실험을 진행하여 재공재고 평균 수준에 대해서는 R2 0.86, 재공재고 최대 수준에 대해서는 R2 0.95의 높은 정확도를 획득하였다. 또한 모델 불특정 해석기법인 SHAP을 활용하여 해석 프레임워크를 함께 제안하였다.
Dexamethasone과 1,25(OH)_2D_3가 배양한 사람 골수기질세포의 증식과 분화에 미치는 영향
김혜수,이일우,이종민,한창환,성진형,박민영,강길선,이해방 대한내분비학회 2002 Endocrinology and metabolism Vol.17 No.2
Background: It is crucial, in the case of regenerating bone by tissue-engineering technique, that osteoblast progenitors are proliferated and induced to differentiate to osteoblasts sequentially at the proper time. Osteoblasts can be obtained from bone itself or from osteoblast progenitors in bone marrow, even though the amount of human marrow stromal cells in marrow aspirate is usually scanty. These cells, however, have been known demonstrate the potential to easily proliferate and differentiate in osteoblasts, chondroblasts or adipocytes according to different microenvironmental factors. We evaluated the effect of dexamethasone and 1,25(OH)_2D_3 on the proliferation, differentiation, and mineralization of human marrow stromal cells in vitro. Methods: We used twelve bone marrow aspirates obtained from different healthy bone marrow donors. Culture plates were randomly divided into the following four experimental groups; group 1 was cultured with control medium only, group 2 with control medium containing 1,25(OH)_2D_3, group 3 with control medium containing dexamethasone, and group 4 with control medium containing both 1,25(OH)_2D_3 and dexamethasone. 3H-thymidine uptake, protein content of cell lysates, alkaline phosphatase activities and alkaline phosphatase histochemistries were measured. Alizarin Red-S staining and quantification of dissolved dye were also performed. Results: Combined stimulation of marrow stromal cells with both 1,25(OH)_2D_3 and dexamethasone was found to be effective to maintain stable long-term culture of the cells and to increased differentiation and mineralization of the cells. Synthesis and mineralization of matrix were highest when the cells were stimulated with 1,25(OH)_2D_3 alone during the early culture phase. However, 1,25(OH)_2D_3 shortened the lifespan of the cells. Interestingly, mineralization was higher in female donor cells than in male donor cells when stimulated with dexamethasone alone or with both dexamethasone and 1,25(OH)_2D_3. Neither 1,25(OH)_2D_3 nor dexamethasone affected cell proliferation. Conclusion: Our results suggest that the synergistic effect of dexamethasone and 1,25(OH)_2D_3 is important in maintaining long-term culture and differentiation of human marrow stromal cells. It is preferable to administer 1,25(OH)_2D_3 after the attachment of cultured osteoblasts to biomaterials has been established, since it could shorten cell survival despite the great increase of mineralization at the early culture phase