• Smart Structures and Systems
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• 제29권3호
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• pp.513-522
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• 2022

Due to the importance of accurate analysis of bearing capacity in civil engineering projects, this paper studies the efficiency of two novel metaheuristic-based models for this objective. To this end, black hole algorithm (BHA) and multi-verse optimizer (MVO) are synthesized with an artificial neural network (ANN) to build the proposed hybrid models. Based on the settlement of a two-layered soil (and a shallow footing) system, the stability values (SV) of 0 and 1 (indicating the stability and failure, respectively) are set as the targets. Each model predicted the SV for 901 stages. The results indicated that the BHA and MVO can increase the accuracy (i.e., the area under the receiving operating characteristic curve) of the ANN from 94.0% to 96.3 and 97.2% in analyzing the SV pattern. Moreover, the prediction accuracy rose from 93.1% to 94.4 and 95.0%. Also, a comparison between the ANN's error decreased by the BHA and MVO (7.92% vs. 18.08% in the training phase and 6.28% vs. 13.62% in the testing phase) showed that the MVO is a more efficient optimizer. Hence, the suggested MVO-ANN can be used as a reliable approach for the practical estimation of bearing capacity.

• 한국지반공학회논문집
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• 제28권10호
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• pp.89-96
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• 2012

본 연구에서는 사면위험도의 합리적인 평가 가중치를 도출하기 위하여 국내의 대표적인 평가방법에 대해 동일한 영향성을 주는 것으로 간주되는 항목들을 그룹화하여 그 영향성을 분석하고 이를 국립방재연구소(NIDP) 평가법과 비교, 사면붕괴 주요인자 선별의 적정성과 배점비율을 검토하였다. 또한, 붕괴가 발생된 28개소 사면을 대상으로 ANN(Artificial Neural Network) 기법을 적용하여 사면붕괴 유발인자 가중치에 대한 합리적 배점이 이루어졌는지에 대해 고찰하였다. ANN기법에 의해 평가비중을 재조정하여 분석한 결과, 국립방재연구소 평가법의 평가비중 오차가 큰 예상피해도, 인장균열, 계곡부 항목의 가중치를 조정하여야 보다 정확한 평가가 가능할 것으로 분석되었다.

• 한국습지학회지
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• 제25권3호
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• pp.167-175
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• 2023

강우 데이터는 습지관리, 수문모의, 수자원 관리와 같은 다양한 분야에서 활용되는 필수 입력자료 중 하나이다. 강우 데이터를 활용하여 효율적인 수자원관리를 위해서는 기본적으로 데이터의 결측률을 최소화 시킴으로써 최대한 많은 데이터를 확보하는 것이 필수적이다. 또한 미계측 지역에 대한 강우 데이터를 확보한다면 보다 효율적인 수문모의가 가능하다. 그러나 결측 강우 데이터는 주로 통계학적 기법에 의해 추정되어 왔다. 본 연구의 목적은 데이터 간의 상관관계를 기반으로 새로운 데이터를 예측할 수 있는 머신러닝 알고리즘을 활용하여 결측 강우 데이터를 복원할 수 있는 새로운 방법을 제안하고자 한다. 또한, 기존의 통계적 방법들과 비교하여 머신러닝 기법의 결측 강우 데이터 복원을 위한 활용가치를 평가하고자 한다. 평가를 위해 대표적인 머신러닝 알고리즘인 Artificial Neural Network (ANN)과 Random Forest (RF)을 적용하였다. 강우의 발생 유무를 분류하는 성능은 RF 알고리즘이 ANN 알고리즘보다 강우 발생유무의 분류 정확도가 높은 것으로 나타났다. 분류 모형의 평가 지표인 F1-score나 Accuracy값이 RF는 0.80, 0.77인 반면에, ANN은 0.76, 0.71로 계산되었다. 또한 강우량을 추정하는 성능 역시 RF가 ANN 알고리즘보다 보다 높은 정확도를 보였다. RF과 ANN 알고리즘의 RMSE은 2.8mm/day과 2.9mm/day이고, R²값은 0.73, 0.68으로 계산되었다.

• Smart Structures and Systems
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• 제25권5호
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• pp.605-617
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• 2020

The existence of damages in structures causes changes in the physical properties by reducing the modal parameters. In this paper, we develop a two-stages approach based on normalized Modal Strain Energy Damage Indicator (nMSEDI) for quick applications to predict the location of damage. A two-dimensional IsoGeometric Analysis (2D-IGA), Machine Learning Algorithm (MLA) and optimization techniques are combined to create a new tool. In the first stage, we introduce a modified damage identification technique based on frequencies using nMSEDI to locate the potential of damaged elements. In the second stage, after eliminating the healthy elements, the damage index values from nMSEDI are considered as input in the damage quantification algorithm. The hybrid of Teaching-Learning-Based Optimization (TLBO) with Artificial Neural Network (ANN) and Particle Swarm Optimization (PSO) are used along with nMSEDI. The objective of TLBO is to estimate the parameters of PSO-ANN to find a good training based on actual damage and estimated damage. The IGA model is updated using experimental results based on stiffness and mass matrix using the difference between calculated and measured frequencies as objective function. The feasibility and efficiency of nMSEDI-PSO-ANN after finding the best parameters by TLBO are demonstrated through the comparison with nMSEDI-IGA for different scenarios. The result of the analyses indicates that the proposed approach can be used to determine correctly the severity of damage in beam structures.

• 한국산업정보학회논문지
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• 제5권3호
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• pp.117-124
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• 2000

시스톨릭 어레이는 간단한 연산능력을 가진 처리요소들이 정규적이고 국부적인 통신 선들로 연결된 병렬처리 시스템이다. 시스톨릭 어레이는 인공신경망에서 고밀하게 연결된 뉴런으로 인하여 발생하는 뉴런간의 복잡한 통신 문제를 해결하는 가장 좋은 방법 중의 하나로 알려져 있다. 본 논문에서는 주어진 뉴런수에 적합한 역전파 인공신경망을 자동으로 생성하는 시스톨릭 어레이 시뮬레이터를 설계하고 구현한다. 시뮬레이터의 애니메이션 기법을 이용하여, 설계된 시스틀릭 어레이 상에서의 역전파 알고리즘의 실행 상황을 사용자들이 단계별로 쉽게 관찰할 수 있다. 또한, 시뮬레이터는 역전파 알고리즘의 전 방향, 역 방향 연산을 각각 따로 실행시키거나, 병렬로 실행하게 할 수 있다. 병렬 실행은 입력 자료를 연속적으로 입력받아 시스톨릭 어레이의 모든 처리요소들에서 역전파 알고리즘의 양방향 전파를 동시에 실행시킴으로써 가능하다.

• 품질경영학회지
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• 제48권2호
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• pp.297-307
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• 2020

Purpose: The purpose of this study is to analyze the factors that affect ammunition performance by applying data mining techniques to the Ammunition Stockpile Reliability Program (ASRP) data of the 155mm propelling charge. Methods: The ASRP data from 1999 to 2017 have been utilized. Logistic regression and decision tree analysis were used to investigate the factors that affect performance of ammunition. The performance evaluation of each model was conducted through comparison with an artificial neural networks(ANN) model. Results: The results of this study are as follows; logistic regression and the decision tree analysis showed that major defect rate of visual inspection is the most significant factor. Also, muzzle velocity by base charge and muzzle velocity by increment charge are also among the significant factors affecting the performance of 155mm propelling charge. To validate the logistic regression and decision tree models, their classification accuracies have been compared with the results of an ANN model. The results indicate that the logistic regression and decision tree models show sufficient performance which conforms the validity of the models. Conclusion: The main contribution of this paper is that, to our best knowledge, it is the first attempt at identifying the significant factors of ASPR data by using data mining techniques. The approaches suggested in the paper could also be extended to other types ammunition data.

• 정보기술응용연구
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• 제1권
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• pp.173-211
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• 1999

The task of classification permeates all walks of life, from business and economics to science and public policy. In this context, nonlinear techniques from artificial intelligence have often proven to be more effective than the methods of classical statistics. The objective of knowledge discovery and data mining is to support decision making through the effective use of information. The automated approach to knowledge discovery is especially useful when dealing with large data sets or complex relationships. For many applications, automated software may find subtle patterns which escape the notice of manual analysis, or whose complexity exceeds the cognitive capabilities of humans. This paper explores the utility of a collaborative learning approach involving integrated models in the preprocessing and postprocessing stages. For instance, a genetic algorithm effects feature-weight optimization in a preprocessing module. Moreover, an inductive tree, artificial neural network (ANN), and k-nearest neighbor (kNN) techniques serve as postprocessing modules. More specifically, the postprocessors act as second0order classifiers which determine the best first-order classifier on a case-by-case basis. In addition to the second-order models, a voting scheme is investigated as a simple, but efficient, postprocessing model. The first-order models consist of statistical and machine learning models such as logistic regression (logit), multivariate discriminant analysis (MDA), ANN, and kNN. The genetic algorithm, inductive decision tree, and voting scheme act as kernel modules for collaborative learning. These ideas are explored against the background of a practical application relating to financial fraud management which exemplifies a binary classification problem.

• 한국멀티미디어학회논문지
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• 제20권2호
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• pp.134-143
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• 2017

Machine fault diagnosis recovers all the studies that aim to detect automatically faults or damages on machines. Generally, it is very difficult to diagnose a machine fault by conventional methods based on mathematical models because of the complexity of the real world systems and the obvious existence of nonlinear factors. This study develops an automatic machine fault diagnosis system that uses pattern recognition techniques such as principal component analysis (PCA) and artificial neural networks (ANN). The sounds emitted by the operating machine, a drill in this case, are obtained and analyzed for the different operating conditions. The specific machine conditions considered in this research are the undamaged drill and the defected drill with wear. Principal component analysis is first used to reduce the dimensionality of the original sound data. The first principal components are then used as the inputs of a neural network based classifier to separate normal and defected drill sound data. The results show that the proposed PCA-ANN method can be used for the sounds based automated diagnosis system.

• Journal of Electrical Engineering and Technology
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• 제4권1호
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• pp.28-34
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• 2009

In a Gas Insulated Substation (GIS), Very Fast Transients (VFTs) are generated mainly due to switching operations. These transients may cause internal faults, i.e., layer-to-layer faults in a capacitively graded bushing as it is one of the most important terminal equipment for GIS. The healthiness of the bushing is generally verified by measuring its leakage current. However, the change in current magnitude/pattern is only marginal for different types of fault conditions. Leakage current monitoring (LCM) systems generate large amounts of data and computer aided interpretation of defects may be of great assistance when analyzing this data. In view of the above, ANN techniques have been used in this study for identification of these minor faults. A single layer perceptron network, a two layer feed-forward back propagation network and cascade correlation (CC) network models are used to identify interlayer faults in the bushing. The effectiveness of the CC network over perceptron and back propagation networks in identification of a fault has been analysed as part of the paper.

• 아태비즈니스연구
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• 제12권4호
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• pp.13-40
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• 2021

Purpose - The purpose of this study is to predict corporate corruption in emerging markets such as Brazil, Russia, India, and China (BRIC) using different machine learning techniques. Since corruption is a significant problem that can affect corporate performance, particularly in emerging markets, it is important to correctly identify whether a company engages in corrupt practices. Design/methodology/approach - In order to address the research question, we employ predictive analytic techniques (machine learning methods). Using the World Bank Enterprise Survey Data, this study evaluates various predictive models generated by seven supervised learning algorithms: k-Nearest Neighbour (k-NN), Naïve Bayes (NB), Decision Tree (DT), Decision Rules (DR), Logistic Regression (LR), Support Vector Machines (SVM), and Artificial Neural Network (ANN). Findings - We find that DT, DR, SVM and ANN create highly accurate models (over 90% of accuracy). Among various factors, firm age is the most significant, while several other determinants such as source of working capital, top manager experience, and the number of permanent full-time employees also contribute to company corruption. Research implications or Originality - This research successfully demonstrates how machine learning can be applied to predict corporate corruption and also identifies the major causes of corporate corruption.