• International Journal of Control, Automation, and Systems
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• 제3권2호
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• pp.236-243
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• 2005

This paper presents a new stochastic approach for solving combinatorial optimization problems by using a new selection method, i.e. SA-selection, in genetic algorithm (GA). This approach combines GA with simulated annealing (SA) to improve the performance of GA. GA and SA have complementary strengths and weaknesses. While GA explores the search space by means of population of search points, it suffers from poor convergence properties. SA, by contrast, has good convergence properties, but it cannot explore the search space by means of population. However, SA does employ a completely local selection strategy where the current candidate and the new modification are evaluated and compared. To verify the effectiveness of the proposed method, the optimization of a fuzzy controller for balancing an inverted pendulum on a cart is considered.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.737-741
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• 1994

We show an application of a genetic algorithm to, control systems including neural networks. Genetic algorithms are getting more popular nowadays because of their simplicity and robustness. Genetic algorithms are global search techniques for optimization and many other problems. A feed-forward neural network which is widely used in control applications usually learns by error back propagation algorithm(EBP). But, when there exist certain constraints, EBP can not be applied. We apply a modified genetic algorithm to such a case. We show simulation examples of two cart-pole nonlinear systems: single pole and double pole.

• Journal of the Korean Data and Information Science Society
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• 제20권1호
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• pp.65-75
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• 2009

대부분의 대학에서는 개설된 강좌에 대한 학생들의 강의만족도를 통하여 교수들의 업적평가에 적용하기 위해 강의평가를 실시하고 있다. 그러나 강의평가점수는 강좌규모, 강의형태, 개설학년 등과 같은 많은 변수들에 의해 영향을 받으며, 그 결과로 강의평가결과는 심각한 편의를 갖는다. 따라서 본 연구에서는 강의평가결과의 사후조정을 위한 균등화방법과 그 효율성을 비교하고, 가장 좋은 효율성을 갖는 균등화방법을 제안하고자 한다.

• 대한안전경영과학회지
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• 제8권1호
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• pp.53-64
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• 2006

Many researches and analyses have been focused on industrial accidents in order to predict and reduce them. As a similar endeavor, this paper is to develop an expert system for prevention of industrial accidents. Although various previous studies have been performed to prevent industrial accidents, these studies only provide managerial and educational policies using frequency analysis and comparative analysis based on data from past industrial accidents. As an initial step for the purpose of this study, this paper provides a comparative analysis of 4 kinds of algorithms including CHAID, CART, C4.5, and QUEST. Decision tree algorithm is utilized to predict results using objective and quantified data as a typical technique of data mining. Enterprise Miner of SAS and Answer Tree of SPSS will be used to evaluate the validity of the results of the four algorithms. The sample for this work was chosen from 10,536 data related to manufacturing industries during three years$(2002\sim2004)$ in korea. The initial sample includes a range of different businesses including the construction and manufacturing industries, which are typically vulnerable to industrial accidents.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2006년도 추계공동학술대회
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• pp.293-297
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• 2006

Recently most universities are suffering from students leaving their majors. In order to make a countermeasure for reducing major separation rate, many universities are trying to find a proper solution. As a similar endeavor, this paper uses decision tree algorithm which is one of the data mining techniques which conduct grouping or prediction into several sub-groups from interested groups. This technique can analyze a feature of type on students leaving their majors. The dataset consists of 5,115 features through data selection from total data of 13,346 collected from a university in Kangwon-Do during seven years(2000.3.1 $\sim$ 2006.6.30). The main objective of this study is to evaluate performance of algorithms including CHAID, CART and C4.5 for classification of students leaving their majors with ROC Chart, Lift Chart and Gains Chart. Also, this study provides values about accuracy, sensitivity, specificity using classification table. According to the analysis result, CART showed the best performance for classification of students leaving their majors.

• 대한안전경영과학회지
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• 제7권4호
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• pp.61-71
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• 2005

Many researches have been focused on the analysis of industry disasters in order to reduce them. As a similar endeavor, this paper provides a propensity analysis of injured people from various industries using classification and regression tree(CART), a data mining algorithm. The sample for this work was chosen from 25,157data related to various industries during one year ( $2003.2\sim2004.1$ ) at Kangwon-Do in Korea. For the purpose of this paper, eight independent variables (injured date, injured time, injured month, type of Injured person, continuous service period, sex, company size, age)are taken from injured person group. According to the analysis result, it is found that five out of the eight factors that are predicted as significant have salient effects. Factors of season, time/hour, day of the week, or month which disasters happened do not show any significant effect. This paper provides common features of injured people. The provided analysis result will be helpful as a starting point for root cause analysis and reduction of industry disasters and also for development of a guideline of safety management.

• 전기전자학회논문지
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• 제20권1호
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• pp.16-25
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• 2016

의학적 진단을 내리기 위해 시행되는 검사의 소요시간(turnaround time, TAT)은 환자대기시간과 직결되며 중요한 의료서비스 평가항목 중 하나이다. 본 연구에서는 주요 영상의학검사를 대상으로 TAT를 측정하고, 그 결과가 의료기관이 설정한 기준치를 달성하는지 여부를 분석하였다. 분류회귀나무 알고리즘을 이용한 예측 결과, "진료과", "상병", "검사종류", "실시월"이 적기처리 달성에 가장 큰 영향을 주는 요인으로 확인되었다. 본 연구는 의료서비스의 적기처리를 예측하는 모형을 통하여 의료서비스 지연을 사전에 조치할 수 있는 수단을 제공하였다는 데에 큰 의미가 있다.

• 한국농공학회논문집
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• 제57권4호
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• pp.1-9
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• 2015

The development of drought index that provides detailed-spatial-resolution drought information is essential for improving drought planning and preparedness. The objective of this study was to develop the concept of using satellite-based hybrid drought index called the Vegetation Drought Response Index in South Korea (VegDRI-SKorea) that could improve spatial resolution for monitoring local and regional drought. The VegDRI-SKorea was developed using the Classification And Regression Trees (CART) algorithm based on remote sensing data such as Normalized Difference Vegetation Index (NDVI) from MODIS satellite images, climate drought indices such as Self Calibrating Palmer Drought Severity Index (SC-PDSI) and Standardized Precipitation Index (SPI), and the biophysical data such as land cover, eco region, and soil available water capacity. A case study has been done for the 2012 drought to evaluate the VegDRI-SKorea model for South Korea. The VegDRI-SKorea represented the drought areas from the end of May and to the severe drought at the end of June. Results show that the integration of satellite imageries and various associated data allows us to get improved both spatially and temporally drought information using a data mining technique and get better understanding of drought condition. In addition, VegDRI-SKorea is expected to contribute to monitor the current drought condition for evaluating local and regional drought risk assessment and assisting drought-related decision making.

• 한국통신학회논문지
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• 제30권7C호
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• pp.675-686
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• 2005

본 논문에서는 효율적인 얼굴 영역 검출 기법을 제안하고 얼굴 객체 검출을 통해 인물 기반의 비디오 시스템을 제공한다. 비디오 분할을 위해 비디오 시퀀스로부터 장면 전환점을 검출하고 분할된 장면들로부터 대표 프레임을 선정한다. 대표 프레임은 인접 프레임 간 변화량이 가장 적은 프레임으로 선정하였으며 추출된 대표 프레임에 대해서 얼굴 영역 검출 알고리즘을 적용하여 등장인물을 포함하는 프레임들을 정보로 제공한다. 얼굴영역 검출을 위해 피부색의 통계적 특성을 이용한 Bayes 분류기를 이용한다. 피부색 검출 결과 영상으로부터 수직 및 수평 투영 기법을 이용하여 영상 분할을 수행하고 후보군들을 생성한다. 생성된 후보군 중 오검출 영역을 최소화하기 위해서 이진 분류 나무(CART)를 이용하여 분류기를 생성한다. 특징 값으로는 SGLD(spatial gray level dependence) 매트릭스로부터 Inertial, Inverse Difference, Correlation 등의 질감 정보를 이용하여 최적의 이진 분류 나무를 생성한다. 실험 결과 제안된 얼굴 영역 검출 알고리즘은 복잡하고 다양한 배경에서도 우수한 성능을 보였으며, 얼굴 객체를 포함하는 프레임들을 비디오 정보로 제공한다. 제안하는 시스템은 향후 화자 인식 기법을 이용하여 등장인물 기반의 비디오 분석 및 에 활용될 수 있을 것이다.

• Transactions on Control, Automation and Systems Engineering
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• 제4권1호
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• pp.84-91
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• 2002

A new composite control method for a carriage balancing single inverted pendulum system is proposed and applied to swing up the pendulum and to stabilize it under the state constraint. The target inverted pendulum system has an extremely limited length of the cart(below 16cm). The proposed swing-up controller comprises a sliding mode control algorithm and an optimal control algorithm based on two regions: the region near the inverted unstable equilibrium position and the rest of the state space including the downward stable equilibrium position. The sliding mode controller uses a switching control action to converge along the specified path(hyperplane) derived from energy equation from a state around the path to desired state(standing position). An optimal control method is also used to guarantee the stability at unstable equilibrium position. Compared with the reported controllers, it is simpler and easier to implement. Experimental results are given to show the effectiveness of this controller.