• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.720-723
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• 2005

Ship motion is a complex controlled process with several hydrodynamic parameters that vary in wide ranges with respect to ship load condition, speed and surrounding conditions (such as wind, current, tide, etc.). Therefore, to effectively control ships in a designed track is always an important task for ship masters. This paper presents an effective adaptive autopilot ships that ensure the optimal accuracy, economy and stability characteristics. The PID control methodology is modified and parameters of a PID controller is designed to satisfy conditions for an optimal objective function that comprised by heading error, resistance and drift during changing course, and loss of surge velocity or fuel consumption. Designing of the controller for course changing process is based on the Model Reference Adaptive System (MRAS) control theory, while as designing of the automatic course keeping process is based on the Self Tuning Regulator (STR) control theory. Simulation (using MATLAB software) in various disturbance conditions shows that in comparison with conventional PID autopilots, the designed autopilot has several notable advantages: higher course turning speed, lower swing of ship bow even in strong waves and winds, high accuracy of course keeping, shorter time of rudder actions smaller times of changing rudder direction.

• Journal of the Ergonomics Society of Korea
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• v.28 no.2
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• pp.9-16
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• 2009

The aim of this study was to evaluate the effects of the driving performance and workload according to changing driving environment and types of steering wheel. Twelve drivers who participated in this study consisted of two groups; six Japanese as the left-lane drivers who was accustomed to driving on left-hand side of the road, and six Europeans, Americans, and Korean as the right-lane drivers who was accustomed to driving on right-hand side of the road. They were asked to operate a driving simulator while using two different types of steering wheel (for the left-hand side driving and the right-hand side driving). During the experiment, a range of data were measured including driving performance, mental workload, and eye movements which were recorded in order to identify the amount of time looking towards the in-vehicle route guidance. Results indicated that the use of the steering wheel by parallel moving led to increase high attentional demand and worse glance behavior to traffic signs for the left-lane drivers. In the case of the right-lane drivers, the effects by changing driving direction were more effective than the types of steering wheel due to their habit or traits.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.5
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• pp.525-529
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• 2009

Most of FLC received input data from error e and change-of-error e' with no relation with system complexity. Basic scheme follows typical PD and PI or PID Controller and that has been developed through fixed ME In this paper, We studied the relationship between MF and system response and system response through changing Fuzzy variable of consequence MF and propose the simple FLC using this relationship. The response of FLC is changed according to the width of Fuzzy variable of consequence MF. As changing the Fuzzy variable of consequence MF shows various nonlinear characteristic, we studied the relation between response and MF using analytical method. We designed the effective FLC using three-variable MF and nine rules and took simulation for verification. In this study, we propose the method to design system with FLC in stability point which is an impotent characteristic of designing system. The circle criterion which is adapted to analysis the nonlinear system is put to use for proposed method. Since SISO FLC has a time-invariant and odd characteristic we can use the critical point not disk which is generally used to determine the stability in the circle criterion, to determine the stability. Using this, we can get the maximum critical point plot of SISO FLC with changing the consequence fuzzy variables. The predetermined critical point plot of FLC can be used to decide the region of the system to be stable. This method is effectively used to design the SISO FLC.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.38
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• pp.207-215
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• 1996

Concurrent Engineering is a concept to aim at product development lead-time in order to satisfy customer's changing tastes in n timely manner. This approach is concurrently integrating all participants and aspects of product design, development and manufacture. In this paper the concepts, framework, and success factor-teamwork- of concurrent engineering is presented.

• Journal for History of Mathematics
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• v.15 no.2
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• pp.77-82
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• 2002

This paper is concerned with the mathematical concept displayed in Buddhism, which is reasonable enough to consider as a philosophy and encompasses the concept of infinity as scientific as that of mathematics. The purpose of this paper is to examine the changing process of the Buddhism concept of infinity on the basis of time sequence and to combine this with that of mathematics.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.72-75
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• 2004

In this paper, the task assignment strategy considering communication delay and the priority of distributed tasks is proposed for the real-time network system in order to maximize the utilization of the system. For the task assignment strategy, the relationship among priority of tasks in network nodes, the calculation time of each task, and the end-to-end response time including the network delay is formulated firstly. Then, the task assignment strategy using the genetic algorithm is proposed to optimize the utilization of the system considering the LCM(Least Common Multiple) period. The effectiveness of proposed strategy is proven by the simulation for estimating the performance such as the utilization and the response time of the system in case of changing the number of tasks and the number of network nodes.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.2
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• pp.36-42
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• 2008

As competition shifts from being a company oriented one to a supply chain oriented, an effective SCM(supply chain management) becomes a necessary strategy for any successful businesses. But, it is not easy to form a successful SCM, because the individual desire of participants conflict with others. These desires affect the performance of SCM and cause waste of cost and time. Analyzing a supply chain of discount retailers, this paper eliminates idle time and improves the process with rearranging the reorder closing time(reorder point). For win-win strategy, this work reveals the reorder closing time is an important factor. It is possible to reduce cost and time on the entire SCM process by just changing the ordering time.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.4
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• pp.154-161
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• 2014

In this research we investigate motion controller performance for mobile robots according to changes in the control loop sampling time. As a result, we suggest a proper range of the sample time, which can minimize final posture errors while improving tracking capability of the controller. For controller implementation into real mobile robots, we use a smooth and continuous motion controller, which can respect robot's path curvature limitation. We examine motion control performance in experimental tests while changing the control loop sampling time. Toward this goal, we compare and analyze experimental results using two different mobile robot platforms; one with real-time control and powerful hardware capability and the other with non-real-time control and limited hardware capability.

• The Journal of Korean Association of Computer Education
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• v.15 no.3
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• pp.71-80
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• 2012

The purpose of this study is to find out the changing trajectory of online game use as the development of early adolescences. It is also to explore whether the self-control has a current and a lag effect on the game use while development of students. We found these results: (a) There is a statically significant individual variability in initial levels and rates of change in online game use over time. The change of trajectory is declined. (b) Boys also have higher rate of the change in using game than girls over time. (c) Both initial state and changing rate of online game use affects negatively the academic achievement. (d) Current effect always supports, but lag effect does not support except the period from last elementary school grade to middle school grade as explanations for the developmental relation between self-control and online game use in young adolescents.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8B
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• pp.986-995
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• 2011

Recently, the market of fiber and apparel industry is rapidly changing from producer to consumer oriented. This trend emphasizes the necessity of SCM systems being able to do flexible correspondences to the market changing through synthetically reflecting consumers' various needs and a variety of patterns. However, because traditional SCMs manage their supply chains being based on bar code systems from the production to the distribution, they are suffering from the needs of real time information sharing and have their essential restrictions in the response to the environmental changes of the market and consumers' needs. This paper suggests a new RFID based u-SCM system optimized into the fiber and apparel industry. The proposed system has the benefits that through basing on RPID can collect information of the production and the distribution real time and make better use of it and connect to the legacy systems organically via Web services and rapidly respond to the market changing and consumers' needs. Through implementation, it is demonstrated that the proposed system can effectively facilitate them.