• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.12
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• pp.577-582
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• 2002

The objective of this paper is to produce a weighted graph map for path-planning of an autonomous mobile robot(AMR) based on the measurements from a single ultrasonic sensor, which are acquired when the autonomous mobile robot explores unknown indoor circumstance. The AMR navigates in th unknown space by following the wall and gathers the range data using the ultrasonic sensor, from which the occupancy grid map is constructed by associating the range data with occupancy certainties. Then, the occupancy grid map is converted to a weighted graph map suing morphological image processing and thinning algorithms. the path- planning for autonomous navigation of a mobile robot can be carried out based on the occupancy grid map. These procedures are implemented and tested using an AMR, and primary results are presented in this paper.

• Industrial Engineering and Management Systems
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• v.7 no.2
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• pp.84-92
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• 2008

Scheduling is one of the most important issues in the planning and operation of production systems. This paper investigates a general job shop scheduling problem with reentrant work flows and sequence dependent setup times. The disjunctive graph representation is used to capture the interactions between machines in job shop. Based on this representation, four two-phase heuristic procedures are proposed to obtain near optimal solutions for this problem. The obtained solutions in the first phase are substantially improved by reversing the direction of some critical disjunctive arcs of the graph in the second phase. A comparative study is conducted to examine the performance of these proposed algorithms.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.126.3-126
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• 2001

A new method to govern the navigation of a mobile robot is proposed based on the following two procedures: one is to achieve vision information by using a 2 D-O-F camera as a communicating medium between a man and a mobile robot and the other is to analyze and to behave according to the recognized hand gesture commands. In the previous researches, mobile robots are passively to move through landmarks, beacons, etc. To incorporate various changes of situation, a new control system manages the dynamical navigation of a mobile robot. Moreover, without any generally used expensive equipments or complex algorithms for hand gesture recognition, a reliable hand gesture recognition system is efficiently implemented to convey the human commands to the mobile robot with a few constraints.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.10a
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• pp.207-210
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• 1996

Learning methodologies such as neural networks or genetic algorithms usually require long training times. Case based reasoning, however, attains peak performance swiftly and is often appropriate for learning even with small data sets. Previous work has shown that an extended case reasoning methodology can yield superior performance in the task of predicting financial data series. This paper examines the impact of reasoning procedures on stock price prediction. The following characteristics are evaluated: size of input vector, multiplicity of neighboring states, and a scaling factor for growth. The concepts are illustrated in the context of predicting the price of an individual price.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.106-108
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• 2002

Recent advances in radiation transport algorithms, computer hardware performance, and parallel computing make the clinical use of Monte Carlo based dose calculations possible. Monte Carlo treatment planning requires accurate beam information as input to generate accurate dose distributions. The procedures to obtain this accurate beam information are called "commissioning", which includes accelerator head modeling. In this study, we would like to investigate how much accurately Monte Carlo based dose calculations can predict the measured beam data in various conditions. The Siemens 6MV photon beam and the BEAM Monte Carlo code were used. The comparisons including the percentage depth doses and off-axis profiles of open fields and wedges, output factors will be presented.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.155-162
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• 1997

Genetic algorithms(GA) are based on the principles of natural genetics and natural selection. The algorithm searches an optimum design point using information based on the fitness function evaluated for the population of many design points. An application of GA on optimal design of a truss structure is studied. The terminology and the operating procedures common in GA are formalized by establishing similarities between GA and genetics from biology. In using GA, (1) coding of the design variables, (2) formulation of the fitness function, (3) setting of the termination condition, and (4) establishment of the probabilities are essential. These four points are discussed in the paper.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.153-160
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• 2003

The objective of optimal placement of dampers for a structure is to maximize the effective-ness of the vibration control with the same number of dampers. While many optimal placement methods of linear viscous dampers have been proposed and used, there are only a few methods for MR dampers. Here some optimal location indices for M dampers are proposed, which are similar to those for linear viscous dampers and show how large the structural responses on each floor are. Every time an additional MR damper is implemented, the optimal location index on each floor is measured, and then the next damper is installed on the floor with the maximum location index. In these sequential procedures, the peak interstory drift, the peak interstory velocity and the absolute acceleration of each floor are selected as the optimal location indeices. Four different earthquakes with various scales are loaded to the 20-story nonlinear benchmark building model (Otori et al. 2000, 2002). Passive On/on algorithms are used in order to represent the control algorithm of M dampers.

• Communications for Statistical Applications and Methods
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• v.11 no.3
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• pp.643-655
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• 2004

L$_1$-estimator in the linear regression model is widely recognized to have superior robustness in the presence of vertical outliers. While the L$_1$-estimation procedures and algorithms have been developed quite well, less progress has been made with the hypothesis test in the multiple L$_1$-regression. This article suggests computer-intensive resampling approaches, jackknife and bootstrap methods, to estimating the variance of L$_1$-estimator and the scale parameter that are required to compute the test statistics. Monte Carlo simulation studies are performed to measure the power of tests in small samples. The simulation results indicate that bootstrap estimation method is the most powerful one when it is employed to the likelihood ratio test.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.467-472
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• 2003

The objective of optimal placement of dampers for a structure is to maximize the effectiveness of the vibration control with the same number of dampers. While many optimal placement methods of linear viscous dampers have been proposed and used, there are only a few methods for MR dampers. Here some optimal location indices for MR dampers are proposed, which are similar to those for linear viscous dampers and show how large the structural responses on each floor we. Every time an additional MR damper is implemented, the optimal location index on each floor is measured, and then the next damper is installed on the floor with the maximum location index. In these sequential procedures, the peak interstory drift, the peak interstory velocity and the absolute acceleration of each floor are selected as the optimal location indeices. Four different earthquakes with various scales are loaded to the 20-story nonlinear benchmark building model (Otori et at. 2000, 2002). Passive On/Off algorithms are used in order to represent the control algorithm of MR dampers.

• Korean Management Science Review
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• v.4
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• pp.76-83
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• 1987

The machine-part group formation(MPGF) problem arises frequently in FMS planning. By viewing the problem as one of finding good assignments, a powerful solution algorithm is presented. The new algorithm solves the threshold dilemma found in previous solution procedures employing similarity coefficients. It also compared favorably with other existing MPGF algorithms by finding minimum exceptional elements for the tested problems. Furthermore the new algorithm can solve dynamic and more realistic MPGF problems by considering production volumes or costs. Such diverse machine-part relationship values were not considered in previous MPGF studies, which included only 0,1 incidence values. An example problem is solved where production volumes are the elements of MPGF incidence matrix.