• 자동차안전학회지
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• 제13권4호
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• pp.129-143
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• 2021

This paper proposes actuator fault detection and adaptive fault-tolerant control algorithms using performance index and human-like learning for longitudinal autonomous vehicles. Conventional longitudinal controller for autonomous driving consists of supervisory, upper level and lower level controllers. In this paper, feedback control law and PID control algorithm have been used for upper level and lower level controllers, respectively. For actuator fault-tolerant control, adaptive rule has been designed using the gradient descent method with estimated coefficients. In order to adjust the control parameter used for determination of adaptation gain, human-like learning algorithm has been designed based on perceptron learning method using control errors and control parameter. It is designed that the learning algorithm determines current control parameter by saving it in memory and updating based on the cost function-based gradient descent method. Based on the updated control parameter, the longitudinal acceleration has been computed adaptively using feedback law for actuator fault-tolerant control. The finite window-based performance index has been designed for detection and evaluation of actuator performance degradation using control error.

• 디지털산업정보학회논문지
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• 제19권3호
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• pp.233-244
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• 2023

Although artificial intelligence and machine learning technologies have been used in various fields, problems with personal information protection have arisen based on centralized data collection and processing. Federated learning has been proposed to solve this problem. Federated learning is a process in which clients who own data in a distributed data environment learn a model using their own data and collectively create an artificial intelligence model by centrally collecting learning results. Unlike the centralized method, Federated learning has the advantage of not having to send the client's data to the central server. In this paper, we quantitatively present the performance improvement when federated learning is applied using the building change detection learning data. As a result, it has been confirmed that the performance when federated learning was applied was about 29% higher on average than the performance when it was not applied. As a future work, we plan to propose a method that can effectively reduce the number of federated learning rounds to improve the convergence time of federated learning.

• 문화기술의 융합
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• 제10권4호
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• pp.595-600
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• 2024

학습 성과를 예측하거나 학습 경로를 최적화하는 연구 분야에서 기계학습과 같은 인공지능 기술의 사용이 점차 증가하면서 교육 분야의 인공지능 활용은 점차 많은 진전을 보이고 있다. 이러한 연구는 점차 심층학습과 강화학습과 같은 좀 더 고도화된 인공지능 방법으로 진화하고 있다. 본 연구는 학습자의 과거 학습 성과-이력 데이터를 기반으로 미래의 학습 성과를 예측하는 방법을 개선하는 것이다. 따라서 예측 성능을 높이기 위해 Markov Chain 방법을 응용한 조건부 확률을 제안한다. 이 방법은 기계학습에 의한 분류 예측에 추가하여 학습자가 학습 이력 데이터를 분류 예측에 추가함으로써 분류기의 예측 성능을 향상 시키기 위해 사용된다. 제안 방법의 효과를 확인하기 위해서 실증 데이터인 '교구 기반의 유아 교육 학습 성과 데이터'를 활용하여 기존의 분류 알고리즘과 제안 방법에 의한 분류 성능 지표를 비교하는 실험을 수행하였다. 실험 결과, 분류 알고리즘만 단독 사용한 사례보다 제안 방법에 의한 사례에서 더 높은 성능 지표를 산출한다는 것을 확인할 수 있었다.

• 통합자연과학논문집
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• 제4권2호
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• pp.158-165
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• 2011

Statistics by structural equation modeling techniques were used to assess a model of chemistry learning strategy based on performance goal orientation. In the optimal Model III of this research, Performance-approach goal was positively related to the use of learning strategy(p<.05) and achievement need(p<.05). Performance-avoidance goal was negatively related to learning strategy(p<.05) and was positively related to self-handicapping tendency(p<.15). Performance-approach goal affected learning strategy indirectly through achievement need(p<.05). Use of achievement need was positively related to learning strategy(p<.05) and self-handicapping tendency(p<.35). Self-handicapping tendency affected learning strategy negatively(p<.05). Implications of these findings for learning strategy in chemistry education are discussed.

• 반도체디스플레이기술학회지
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• 제20권1호
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• pp.64-69
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• 2021

In this paper, a method for improving the defect classification performance in low contrast, ununiformity and featureless steel plate surfaces has been studied based on deep convolution neural network and transfer-learning neural network. The steel plate surface images have low contrast, ununiformity, and featureless, so that the contrast between defect and defect-free regions are not discriminated. These characteristics make it difficult to extract the feature of the surface defect image. A classifier based on a deep convolution neural network is constructed to extract features automatically for effective classification of images with these characteristics. As results of the experiment, AlexNet-based transfer-learning classifier showed excellent classification performance of 99.43% with less than 160 seconds of training time. The proposed classification system showed excellent classification performance for low contrast, ununiformity, and featureless surface images.

• 수산해양교육연구
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• 제27권1호
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• pp.108-114
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• 2015

The purpose of this study is to find the relationships among communication competency, social network centrality(trust centrality and knowledge sharing centrality), discussion performance, and online boarding activity in the team based learning situation. For investigating this topic, 44 students are participated in the classes of educational technology. In order to find out the relationships among communication competency, social network centrality, discussion performance, and online boarding activity, compared t-test and path analysis are used. Followings are the results of the research: (a) Communication competency is improved significantly after team based learning. (b) Trust centrality effects significantly on the knowledge sharing centrality. (c) Knowledge sharing effects significantly on discussion performance. (d) Trust centrality effects on the online boarding activity in the team based learning.

• 한국군사과학기술학회지
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• 제24권5호
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• pp.558-568
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• 2021

The existing underwater vehicle controller design is applied by linearizing the nonlinear dynamics model to a specific motion section. Since the linear controller has unstable control performance in a transient state, various studies have been conducted to overcome this problem. Recently, there have been studies to improve the control performance in the transient state by using reinforcement learning. Reinforcement learning can be largely divided into value-based reinforcement learning and policy-based reinforcement learning. In this paper, we propose the roll controller of underwater vehicle based on Deep Deterministic Policy Gradient(DDPG) that learns the control policy and can show stable control performance in various situations and environments. The performance of the proposed DDPG based roll controller was verified through simulation and compared with the existing PID and DQN with Normalized Advantage Functions based roll controllers.

• International Journal of Internet, Broadcasting and Communication
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• 제15권3호
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• pp.231-238
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• 2023

As the demand for distance education increases, interest in the management of learners' rights is increasing. Blockchain technology is a technology that guarantees the integrity of the learner's learning history, and enables learner-led learning control, data security, and sharing of learning resources. In this paper, we proposed a blockchain technology-based learning management system based on Hyperledger Fabric that can be verified through permission between nodes among blockchain platforms. Learning resources can be shared differentially according to the learning progress. Also the percentage of individual learners that can be managed. As a result of the study, the superiority of the platform in terms of convenience compared to the existing platform was demonstrated. As a result of the performance evaluation for the research in this paper, it was confirmed that the convenience was improved by more than 5%, and the performance was 4-5% superior to the existing platform in terms of learner satisfaction.

• 한국임상약학회지
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• 제23권3호
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• pp.278-283
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• 2013

Background: Problem-based learning (PBL) has introduced as an important part of pharmacy education in Korea as it is effective method to help students gain and apply knowledge with development of problem-solving, critical-thinking, and decision-making skills. In order to provide the effective PBL, a number of trained facilitators and suitable PBL rooms are required. However, these become a barrier in Korea as most pharmacy schools have one or two faculty members who majored in clinical pharmacy. Objective: This study was performed to implement and evaluate a modified PBL in gastrointestinal (GI) pharmacotherapy class facilitated by one instructor. Methods: A general information of traditional PBL for 6 hours through 3 days is introduced before initiating GI pharmacotherapy class. After 3 hour-GI pharmacotherapy classes for 6 weeks, modified PBL was implemented with one instructor to facilitate PBL for four small groups with 19 pharmacy students simultaneously. Modified PBL was incorporated with weekly mini-case discussion and presentation. Results: Students completed 15-question survey to evaluate modified PBL course, student performance, group performance, and facilitator performance. Eighty-four percent of students answered modified PBL was helpful to understand what they have learned. Mean score in group performance was higher than that of individual performance during modified PBL course. Overall, students reported modified PBL was useful in knowledge building. Conclusion: Modified PBL model without individual group facilitators in one classroom helped students to achieve self-directed, independent learning skills in an interactive and engaging environment.

• 전기전자학회논문지
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• 제23권1호
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• pp.120-126
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• 2019

최근 에너지 인터넷에서 지능형 원격검침 인프라를 이용하여 확보된 대량의 전력사용데이터를 기반으로 효과적인 전력수요 예측을 위해 다양한 기계학습기법에 관한 연구가 활발히 진행되고 있다. 본 연구에서는 전력량 데이터와 같은 시계열 데이터에 대해 효율적으로 패턴인식을 수행하는 인공지능 네트워크인 Gated Recurrent Unit(GRU)을 기반으로 딥 러닝 모델을 제안하고, 실제 가정의 전력사용량 데이터를 토대로 예측 성능을 분석한다. 제안한 학습 모델의 예측 성능과 기존의 Long Short Term Memory (LSTM) 인공지능 네트워크 기반의 전력량 예측 성능을 비교하며, 성능평가 지표로써 Mean Squared Error (MSE), Mean Absolute Error (MAE), Forecast Skill Score, Normalized Root Mean Squared Error (RMSE), Normalized Mean Bias Error (NMBE)를 이용한다. 실험 결과에서 GRU기반의 제안한 시계열 데이터 예측 모델의 전력량 수요 예측 성능이 개선되는 것을 확인한다.