• 한국BIM학회 논문집
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• 제8권3호
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• pp.12-19
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• 2018

The research aims to find implications of machine learning and urban big data as a way to construct the flexible transportation network system of smart city by responding the urban context changes. This research deals with a problem that existing a bus headway model is difficult to respond urban situations in real-time. Therefore, utilizing the urban big data and machine learning prototyping tool in weathers, traffics, and bus statues, this research presents a flexible headway model to predict bus delay and analyze the result. The prototyping model is composed by real-time data of buses. The data is gathered through public data portals and real time Application Program Interface (API) by the government. These data are fundamental resources to organize interval pattern models of bus operations as traffic environment factors (road speeds, station conditions, weathers, and bus information of operating in real-time). The prototyping model is implemented by the machine learning tool (RapidMiner Studio) and conducted several tests for bus delays prediction according to specific circumstances. As a result, possibilities of transportation system are discussed for promoting the urban efficiency and the citizens' convenience by responding to urban conditions.

• 한국BIM학회 논문집
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• 제11권2호
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• pp.24-32
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• 2021

Recently, starting with smart construction research, interest in technology that automates construction site management using artificial intelligence technology is increasing. In order to automate construction site management, it is necessary to recognize objects such as construction equipment or workers, and automatically analyze the relationship between them. For example, if the relationship between workers and construction equipment at a construction site can be known, various use cases of site management such as work productivity, equipment operation status monitoring, and safety management can be implemented. This study derives a real-time object detection platform architecture that is required when performing construction site management using deep learning technology, which has recently been increasingly used. To this end, deep learning models that support real-time object detection are investigated and analyzed. Based on this, a deep learning model development process required for real-time construction site object detection is defined. Based on the defined process, a prototype that learns and detects construction site objects is developed, and then platform development considerations and architecture are derived from the results.

• Korean Journal of Radiology
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• 제22권10호
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• pp.1697-1707
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• 2021

The recent introduction of various high-dimensional modeling methods, such as radiomics and deep learning, has created a much greater diversity in modeling approaches for survival prediction (or, more generally, time-to-event prediction). The newness of the recent modeling approaches and unfamiliarity with the model outputs may confuse some researchers and practitioners about the evaluation of the performance of such models. Methodological literacy to critically appraise the performance evaluation of the models and, ideally, the ability to conduct such an evaluation would be needed for those who want to develop models or apply them in practice. This article intends to provide intuitive, conceptual, and practical explanations of the statistical methods for evaluating the performance of survival prediction models with minimal usage of mathematical descriptions. It covers from conventional to deep learning methods, and emphasis has been placed on recent modeling approaches. This review article includes straightforward explanations of C indices (Harrell's C index, etc.), time-dependent receiver operating characteristic curve analysis, calibration plot, other methods for evaluating the calibration performance, and Brier score.

• 대한안전경영과학회지
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• 제25권2호
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• pp.159-165
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• 2023

The entire industry is increasing the use of big data analysis using artificial intelligence technology due to the Fourth Industrial Revolution. The value of big data is increasing, and the same is true of the production technology. However, small and medium -sized manufacturers with small size are difficult to use for work due to lack of data management ability, and it is difficult to enter smart factories. Therefore, to help small and medium -sized manufacturing companies use big data, we will predict the gross production time through machine learning. In previous studies, machine learning was conducted as a time and quantity factor for production, and the excellence of the ExtraTree Algorithm was confirmed by predicting gross product time. In this study, the worker's proficiency factors were added to the time and quantity factors necessary for production, and the prediction rate of LightGBM Algorithm knowing was the highest. The results of the study will help to enhance the company's competitiveness and enhance the competitiveness of the company by identifying the possibility of data utilization of the MES system and supporting systematic production schedule management.

• 한국인공지능학회지
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• 제11권4호
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• pp.21-27
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• 2023

This paper discusses a deep learning-based road surface analysis system that collects data by installing vibration sensors on the 4-axis wheel bearings of a vehicle, analyzes the data, and appropriately classifies the characteristics of the current driving road surface for use in the vehicle's control system. The data used for road surface analysis is real-time large-capacity data, with 48K samples per second, and the A2B protocol, which is used for large-capacity real-time data communication in modern vehicles, was used to collect the data. CAN and CAN-FD commonly used in vehicle communication, are unable to perform real-time road surface analysis due to bandwidth limitations. By using A2B communication, data was collected at a maximum bandwidth for real-time analysis, requiring a minimum of 24K samples/sec for evaluation. Based on the data collected for real-time analysis, performance was assessed using deep learning models such as LSTM, GRU, and RNN. The results showed similar road surface classification performance across all models. It was also observed that the quality of data used during the training process had an impact on the performance of each model.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1995년도 춘계공동학술대회논문집; 전남대학교; 28-29 Apr. 1995
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• pp.869-879
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• 1995

The new field of learning control develops controllers that learn to improve their performance at executing a given task, based on experience performing this task. The simplest forms of learning control are based on the same concept as integral control, but operating in the domain of the repetitions of the task. In the previous paper, I had studied the use of such controllers in a decentralized system, such as a robot with the controller for each link acting independently. The basic result of the paper is to show that stability of the learning controllers for all subsystems when the coupling between subsystems is turned off, assures stability of the decentralized learning in the coupled system, provided that the sample time in the digital learning controller is sufficiently short. In this paper, we present two examples. The first illustrates the effect of coupling between subsystems in the system dynamics, and the second studies the application of decentralized learning control to robot problems. The latter example illustrates the application of decentralized learning control to nonlinear systems, and also studies the effect of the coupling between subsystems introduced in the input matrix by the discretization of the system equations. The conclusion is that for sufficiently small learning gain, and sufficiently small sample time, the simple learning control law based on integral control applied to each robot axis will produce zero tracking error in spite o the dynamic coupling in the robot equations. Of course, the results of this paper have much more general application than just to the robotics tracking problem. Convergence in decentralized systems is seen to depend only on the input and output matrices, provided the sample time is suffiently small.

• 한국전산구조공학회논문집
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• 제36권1호
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• pp.39-48
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• 2023

철도교량의 설계는 장기간에 걸쳐 수행되고 대규모의 부지를 대상으로 하기 때문에 다양한 환경적인 요인과 불확실성을 동반하게 된다. 이러한 연유로 초기 설계단계에서 충분히 검토하였더라도 설계변경이 종종 발생하고 있다. 특히 철도교량과 같은 대규모 시설물의 설계변경은 많은 시간과 인력을 소모하며, 매번 모든 절차를 반복하는 것은 매우 비효율적이다. 본 연구에서는 딥러닝 알고리즘 중 전이학습을 통해 설계변경 전의 학습 결과를 활용하여 설계변경 후의 학습의 효율성을 향상시킬 수 있는 기법을 제안하였다. 분석을 위해 기개발한 철도교량 딥러닝 기반 예측 시스템을 활용하여 시나리오들을 작성하고 데이터베이스를 구축하였다. 제안된 기법은 설계변경 전 기존 도메인에서 학습에 사용한 8,000개의 학습데이터 대비 새로운 도메인에서 1,000개의 데이터만을 학습하여 유사한 정확도를 나타내었고 보다 빠른 수렴속도를 가지는 것을 확인하였다.

• 품질경영학회지
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• 제48권3호
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• pp.511-520
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• 2020

Purpose: The purpose of this study was to devise an accurate machine learning model for predicting silica concentrations following the addition of impurities, through time series analysis of mining data. Methods: The mining data were preprocessed and subjected to time series analysis using the machine learning model. Through correlation analysis, valid variables were selected and meaningless variables were excluded. To reflect changes over time, dependent variables at baseline were treated as independent variables at later time points. The relationship between independent variables and the dependent variable after n point was subjected to Pearson correlation analysis. Results: The correlation (R2) was strongest after 3 hours, which was adopted as a dependent variable. According to root mean square error (RMSE) data, the proposed method was superior to the other machine learning methods. The XGboost algorithm showed the best predictive performance. Conclusion: This study is important given the current lack of machine learning studies pertaining to the domestic mining industry. In addition, using time series analysis in mining data will show further improvement. Before establishing a predictive model for the proposed method, predictions should be made using data with time series characteristics. After doing this work, it should also improve prediction accuracy in other domains.

• 한국산학기술학회논문지
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• 제20권7호
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• pp.249-254
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• 2019

인공지능(AI), 사물인터넷(IoT), 빅데이터 등 4차 산업혁명에 따른 지능 정보기술의 발전과 함께 교육 분야도 이러닝(e-Learning)을 중심으로 빠르게 재편되며 '에듀테크' 개념이 확산되고 있다. 현재 선행업체들이 온라인 교육 서비스를 실시하고 있으나 실시간으로 이루어지는 양방향 커뮤니케이션이 어렵다. 또한, 오프라인 수업의 경우 학생의 수가 많고, 시간이 한정되어 있을 뿐 만 아니라 질문할 기회를 갖지 못하는 경우가 많다. 본 논문은 이러한 문제들을 해결하기 위해 오프라인이 가지는 즉문즉답의 효율성과 온라인에서의 개방성이라는 장점을 접목하여 온라인과 오프라인상에서의 질문을 자유롭게 할 수 있는 실시간 양방향 학습 질문 및 답변 운영 시스템을 개발한다. 개발된 시스템은 실시간 개인별 맞춤형 교육 시스템으로서 답변자가 질문자의 상황을 실시간으로 확인하고 질문자의 요청에 맞는 맞춤형 답변을 제공함으로써 한 번의 연결로 질문을 해결할 수 있다. 또한 시스템의 이용 시간을 초단위로 측정하여 관리함으로써 질문자와 답변자가 효율적으로 시스템을 활용하게 할 수 있다.

• 디지털융복합연구
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• 제18권1호
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• pp.369-377
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• 2020

본 연구의 목적은 한국과 중국의 이러닝 품질과 학습자의 이용동기가 이러닝 만족도에 미치는 영향력을 밝히는데 있다. 또한 두 국가 간 학습자들의 만족도에 영향을 미치는 요인을 비교 분석해 봄으로서 효과적인 이러닝 활용 방안을 제시하고자 하였다. 본 연구는 경상북도에 소재한 Y대학과 K대학의 한국인 대학생과 중국 허난성에 소재한 A대학의 중국인 대학생을 대상으로 설문조사를 실시하였다. 그 결과 한국인 대학생은 학습시간, 학습공간, 학습과정, 유용성 그리고 이러닝 정보 품질, 서비스 품질이 이러닝 만족도에 영향을 미치는 것으로 나타났다. 중국인 대학생은 학습시간, 학습과정 그리고 이러닝 시스템 품질, 정보 품질, 서비스 품질이 이러닝 만족도에 영향을 미치는 것으로 나타났다. 그 중 서비스 품질은 두 국가 모두 이러닝 만족도에 영향을 미치는 중요한 요인으로 나타났지만, 요인별 평균 점수는 매우 낮게 나타났다. 향후 서비스 품질을 개선할 방안에 대해서 논의하였다.