• IEIE Transactions on Smart Processing and Computing
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• 제5권1호
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• pp.17-21
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• 2016

This paper investigates the importance of the computational overhead when machine learning methods, such as SVM, LASSO, AdaBoosting and AdaBagging, are used for automatic security classification.

• 한국건설관리학회논문집
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• 제24권6호
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• pp.3-11
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• 2023

건설산업의 높은 재해율을 줄이고자, VR 기반 건설안전교육의 도입이 장려되고 있다. 그러나 학습자의 특성을 고려하지 않은 교육방식으로 인해, 학습자의 개인특성에 맞는 효과적인 교육을 수행하지 못하는 한계가 있다. 본 연구에서는, VR 기반 건설안전교육에서 학습성과에 영향을 미치는 개인특성을 분석하는 것으로 목표로 하였고, 이를 위해 머신러닝과 SHAP 기법을 활용하였다. SHAP 분석 결과, 연령이 학습성과에 가장 많은 영향을 미치는 것으로 나타났고, 경력이 가장 작은 영향을 미치는 것으로 나타났다. 또한, 연령은 학습성과와 음(-)의 상관관계를 보이고 있어, VR 기반 건설안전교육의 도입은 낮은 연령에게 더 효과적일 수 있는 것으로 나타났다. 반면, 학력, 자격, 경력은 양(+)의 상관관계를 보였다. 학력이 낮은 학습자에게 더욱 이해하기 쉬운 컨텐츠를 제공함으로써, 학습성과를 향상시킬 필요가 있다. 또한, 자격과 경력이 낮은 학습자의 특성은 학습성과에 영향을 거의 미치지 않으므로, 그 이외의 학습자 특성에 집중함으로써, 학습자 맞춤형 교육 컨텐츠를 제공할 수 있을 것으로 기대된다. 본 연구를 통해, 여러 개인특성이 학습성과에 서로 다른 영향을 미칠 수 있음을 확인했고, 이러한 결과를 활용함으로써, 건설근로자의 개인특성을 고려한 효과적인 안전교육의 기회를 제공할 수 있을 것으로 기대된다.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2297-2310
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• 2022

A condensation heat transfer model is essential to accurately predict the performance of the passive containment cooling system (PCCS) during an accident in an advanced light water reactor. However, most of existing models tend to predict condensation heat transfer very well for a specific range of thermal-hydraulic conditions. In this study, a new correlation for condensation heat transfer coefficient (HTC) is presented using machine learning technique. To secure sufficient training data, a large number of pseudo data were produced by using ten existing condensation models. Then, a neural network model was developed, consisting of a fully connected layer and a convolutional neural network (CNN) algorithm, DenseNet. Based on the hold-out cross-validation, the neural network was trained and validated against the pseudo data. Thereafter, it was evaluated using the experimental data, which were not used for training. The machine learning model predicted better results than the existing models. It was also confirmed through a parametric study that the machine learning model presents continuous and physical HTCs for various thermal-hydraulic conditions. By reflecting the effects of individual variables obtained from the parametric analysis, a new correlation was proposed. It yielded better results for almost all experimental conditions than the ten existing models.

• International Journal of Advanced Culture Technology
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• 제5권2호
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• pp.82-89
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• 2017

The range of problems that can be handled by the activation of big data and the development of hardware has been rapidly expanded and machine learning such as deep learning has become a very versatile technology. In this paper, mnist data set is used as experimental data, and the Cross Entropy function is used as a loss model for evaluating the efficiency of machine learning, and the value of the loss function in the steepest descent method is We applied the GradientDescentOptimize algorithm to minimize and updated weight and bias via backpropagation. In this way we analyze optimal reliability value corresponding to the number of exercises and optimal reliability value without overfitting. And comparing the overfitting time according to the number of data changes based on the number of training times, when the training frequency was 1110 times, we obtained the result of 92%, which is the optimal reliability value without overfitting.

• 정보처리학회 논문지
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• 제13권2호
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• pp.76-90
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• 2024

인공지능 기술은 스마트 시티, 자율 주행, 의료 분야 등 다양한 분야에서 활용 가능성을 높이 평가받고 있으나, 정보주체의 개인정보 및 민감정보의 노출 문제로 모델 활용이 제한되고 있다. 이에 따라 데이터를 중앙 서버에 모아서 학습하지 않고, 보유 데이터셋을 바탕으로 일차적으로 학습을 진행한 후 글로벌 모델을 최종적으로 학습하는 분산 기계 학습의 개념이 등장하였다. 그러나, 분산 기계 학습은 여전히 협력하여 학습을 진행하는 과정에서 데이터 프라이버시 위협이 발생한다. 본 연구는 분산 기계 학습 연구 분야에서 프라이버시를 보호하기 위한 연구를 서버의 존재 유무, 학습 데이터셋의 분포 환경, 참여자의 성능 차이 등 현재까지 제안된 분류 기준들을 바탕으로 유기적으로 분석하여 최신 연구 동향을 파악한다. 특히, 대표적인 분산 기계 학습 기법인 수평적 연합학습, 수직적 연합학습, 스웜 학습에 집중하여 활용된 프라이버시 보호 기법을 살펴본 후 향후 진행되어야 할 연구 방향을 모색한다.

• 한국콘텐츠학회논문지
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• 제19권1호
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• pp.1-15
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• 2019

직업훈련 교육 현장에서 느끼는 가장 큰 어려움 중 하나는 중도탈락 문제이다. 훈련과정마다 많은 수의 학생들이 중도탈락을 하게 되어 국가 예산 낭비 및 청년 취업률 개선에 장애 요인이 되고 있다. 본 연구에서는 중도탈락의 원인을 주로 분석한 기존 연구들과 달리, 각종 수강생 정보를 활용하여 사전에 중도탈락을 예측할 수 있는 기계학습 기반 모형을 제안하고자 한다. 특히 본 연구의 제안모형은 수강생 관련 정형 데이터 뿐 아니라 비정형 데이터인 강사의 상담일지 정보까지 동시에 고려하여 모형의 예측정확도를 제고하고자 하였다. 이 때 비정형 데이터에 대한 분석은 최근 주목받고 있는 텍스트 분석 기술인 Word2vec과 합성곱 신경망을 이용해 수행하였다. 국내 한 직업훈련기관의 실제 데이터에 제안모형을 적용해 본 결과, 정형데이터만을 사용하여 중도탈락을 예측할 때보다 비정형 데이터를 함께 고려했을 때 예측의 정확도가 최대 20%까지 향상됨을 확인할 수 있었다. 아울러, Support Vector Machine을 기반으로 정형 데이터와 비정형 데이터를 결합해 분석했을 때, 검증용 데이터셋 기준으로 90% 후반대의 높은 예측 정확도를 나타냄을 확인하였다.

• 한국분무공학회지
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• 제27권2호
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• pp.57-65
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• 2022

The purpose of this study is to use machine learning to build a model capable of predicting the flash boiling spray characteristics. In this study, the flash boiling spray was visualized using Shadowgraph visualization technology, and then the spray image was processed with MATLAB to obtain quantitative data of spray characteristics. The experimental conditions were used as input, and the spray characteristics were used as output to train the machine learning model. For the machine learning model, the XGB (extreme gradient boosting) algorithm was used. Finally, the performance of machine learning model was evaluated using R² and RMSE (root mean square error). In order to have enough data to train the machine learning model, this study used 12 injectors with different design parameters, and set various fuel temperatures and ambient pressures, resulting in about 12,000 data. By comparing the performance of the model with different amounts of training data, it was found that the number of training data must reach at least 7,000 before the model can show optimal performance. The model showed different prediction performances for different spray characteristics. Compared with the upstream spray angle and the downstream spray angle, the model had the best prediction performance for the spray tip penetration. In addition, the prediction performance of the model showed a relatively poor trend in the initial stage of injection and the final stage of injection. The model performance is expired to be further enhanced by optimizing the hyper-parameters input into the model.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권3호
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• pp.21-34
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• 2016

In the present study, we applied various machine learning techniques comparatively for prediction of subsurface structures based on multiple secondary information (i.e., well-logging data). The machine learning techniques employed in this study are Naive Bayes classification (NB), artificial neural network (ANN), support vector machine (SVM) and logistic regression classification (LR). As an alternative model, conventional hidden Markov model (HMM) and modified hidden Markov model (mHMM) are used where additional information of transition probability between primary properties is incorporated in the predictions. In the comparisons, 16 boreholes consisted with four different materials are synthesized, which show directional non-stationarity in upward and downward directions. Futhermore, two types of the secondary information that is statistically related to each material are generated. From the comparative analysis with various case studies, the accuracies of the techniques become degenerated with inclusion of additive errors and small amount of the training data. For HMM predictions, the conventional HMM shows the similar accuracies with the models that does not relies on transition probability. However, the mHMM consistently shows the highest prediction accuracy among the test cases, which can be attributed to the consideration of geological nature in the training of the model.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.136-136
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• 2022

This study investigates the possibility of coupling empirical mode decomposition (EMD) for runoff prediction from machine learning (ML) models. Here, support vector regression (SVR) and convolutional neural network (CNN) were considered for ML algorithms. Precipitation (P), minimum temperature (Tmin), maximum temperature (Tmax) and their intrinsic mode functions (IMF) values were used for input variables at a monthly scale from Jan. 1973 to Dec. 2020 in the Grand river basin, Canada. The support vector machine-recursive feature elimination (SVM-RFE) technique was applied for finding the best combination of predictors among input variables. The results show that the proposed method outperformed the individual performance of SVR and CNN during the training and testing periods in the study area. According to the correlation coefficient (R), the EMD-SVR model outperformed the EMD-CNN model in both training and testing even though the CNN indicated a better performance than the SVR before using IMF values. The EMD-SVR model showed higher improvement in R value (38.7%) than that from the EMD-CNN model (7.1%). It should be noted that the coupled models of EMD-SVR and EMD-CNN represented much higher accuracy in runoff prediction with respect to the considered evaluation indicators, including root mean square error (RMSE) and R values.

• Journal of Information Processing Systems
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• 제18권5호
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• pp.701-710
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• 2022

With the development of artificial intelligence technology, various methods have been developed for recognizing objects in images using machine learning. Image segmentation is the most effective among these methods for recognizing objects within an image. Conventionally, image datasets of various classes are trained simultaneously. In situations where several classes require segmentation, all datasets have to be trained thoroughly. Such repeated training results in low training efficiency because most of the classes have already been trained. In addition, the number of classes that appear in the datasets affects training. Some classes appear in datasets in remarkably smaller numbers than others, and hence, the training errors will not be properly reflected when all the classes are trained simultaneously. Therefore, a new method that separates some classes from the dataset is proposed to improve efficiency during training. In addition, the accuracies of the conventional and proposed methods are compared.