• 제어로봇시스템학회:학술대회논문집
• /
• 1993.10a
• /
• pp.14-19
• /
• 1993

In this paper, we proposed an indirect learning and direct adaptive control schemes using neural networks, i.e., composite adaptive neural control, for a class of continuous nonlinear systems. With the indirect learning method, the neural network learns the nonlinear basis of the system inverse dynamics by a modified backpropagation learning rule. The basis spans the local vector space of inverse dynamics with the direct adaptation method when the indirect learning result is within a prescribed error tolerance, as such this method is closely related to the adaptive control methods. Also hash addressing technique, similar to the CMAC functional architecture, is introduced for partitioning network hidden nodes according to the system states, so global neuro control properties can be organized by the local ones. For uniform stability, the sliding mode control is introduced when the neural network has not sufficiently learned the system dynamics. With proper assumptions on the controlled system, global stability and tracking error convergence proof can be given. The performance of the proposed control scheme is demonstrated with the simulation results of a nonlinear system.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.2
• /
• pp.176-184
• /
• 2001

The VDC(Vehicle Dynamics Control) is a control system whose target is to improve vehicle stability under critical motion. The system has a good potential of becoming a standard active safety unit in passenger vehicles since it can be implemented on top of the ABS/TCS system with little extra cost. This, however, is possible only when the signals that the VDC system demands can be obtained with sufficient accuracy. In this research, estimators for the road friction coefficient and body sideslip angle have been designed. The two variables have great influence upon performance of the VDC system but not directly measurable. For the estimator design, the Newton method and the nonlinear observer theory have been exploited. The performance of the estimator have been verified via simulations on critical driving conditions.

• Journal of Families and Better Life
• /
• v.14 no.4
• /
• pp.71-84
• /
• 1996

The purposes of this study were to classify the family types based on the intra system dynamics and to examine sociodemographic backgrounds and the life satisfaction of these families. The data were collected by means of questionnaire distributed to a stratified sample of 544 housewives in Seoul who lived with housbands and children. The questionnaire included FACES II and III Communication Scale managerial behavior scale and life satisfaction Scale. Frequency percentile mean correlation factor analysis cluster analysis one-way ANOVA with scheffe test and chi-square test were used to analyze the data. This study had resulted in four major findings. The first was that highly positive relationships were found among four intra system dynamics elements. The first was that highly positive relationships were found among four intra system dynamics elements. The second finding was that families were clustered by four types named personal-oriented enervated dynamic and managerial-orien ed family. The third finding was that the four types of family were influenced by education level and job of husbands and family income. The last one was that the differences in life satisfaction were found among four types of family. The housewives of dynamic family type showed the highest level of satisfaction whereas the lowest level of life satisfaction was found among housewives of enervated family type. The recommendations for future esearch and better ways to educate and counsel families were suggested.

• Korean System Dynamics Review
• /
• v.14 no.3
• /
• pp.105-134
• /
• 2013

Electrical construction business has public and professional characters. It may require appropriate interventions of the government because these business activities stand for not only profit-seeking competition, but also supplies of one of the key functions in our society. In other words, public benefit and private benefit are still in existence. The government therefore considers such an aspect of public importance of the business sector and needs to plan to adjust technical and engineering manpower of this market. This study focuses on the imbalance for labor supply and demand of technical engineer in electrical construction business. A system dynamics analysis is applied to understand and simulate the imbalance as a soft approach. It has the merit of causal loop diagram to alleviate the limitation of data lack problem. We find that excess demand is expected from 2010 to 2011, and excess supply is predicted from 2012 to 2021 about the manpower of technical engineer. It shows considerable disagreement between the supply and demand of human resource. So we suggest that it is strong necessity to construct statistics infrastructure for a manpower supply and demand plan.

• Korean System Dynamics Review
• /
• v.15 no.2
• /
• pp.5-25
• /
• 2014

The purpose of this study is to analyze the effects of nuclear power plant workers and organizational characteristics on accidents, and seek the combination of policies for reducing accidents. For this purpose, it grasped, by using System Dynamics and Causal Loop Diagram, how various factors that cause accidents in nuclear plants are interrelated, and performed simulations after building simulation models. As a result of the analysis, first, the fundamental cause of safety accidents in nuclear power plants turned out to be the time constraint on the workload. Second, it turned out that as the workload of workers increases, physical and mental stresses increase, thereby increasing accidents due to errors and violations. Third, it turned out that as the levels of educational training and compliance with regulations and procedures are enhanced, accidents are reduced. Lastly, it turned out that as the combination of policies (reliance level + working environment + educational training + compliance with regulations and procedures) is increased, accidents are reduced. Especially, it turned out that if the combination of policies is increased by 30%, more than 10 cases of accidents are reduced.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08a
• /
• pp.283-285
• /
• 2007

This paper will discuss the latest results from an advanced array test system, using newly developed sensor technology. A comparison of detection results between old and new generation products will be shown along with a discussion of the advantages of the new, higher signal to noise ratio detector.

• Journal of the Korea Institute of Building Construction
• /
• v.11 no.3
• /
• pp.221-228
• /
• 2011

This study is on the development of a System Dynamics Model for business feasibility analysis of an apartment house development project. In this study, we analyzed other apartment development projects and research projects, and identified the cash flow items, which consist of revenue and expenditure items. In addition, we made efforts to find the influence relationship among these using the system thinking method and developed a system dynamics model. In order to test the model, a case study was conducted in which it was applied to an apartment development project. Vensim, a System Dynamics Modeling and simulation software package was used to analyze and test the model. The model suggested in this study can help a developer to make decisions on project financing at the initial stage of an apartment house development project.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.2B
• /
• pp.228-239
• /
• 2004

Information Security industry in Korea is growing rapidly but is confronted with many challenges in business environment. One of the worst hardships is the mismatch in the demand and supply of manpower. Thus the government is developing a manpower policy to relieve the situation. To suggest policy implications, this study analyzes the demand and supply of Information Security manpower in the systematic and behavioral point of views. Using System Dynamics approach, we formulate a model to analyze the demand and supply of Information Security manpower. Finally we simulate the model and interpret the results.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.5C
• /
• pp.642-653
• /
• 2004

Information Security industry in Korea is growing rapidly but is confronted with many challenges in business environment. One of the worst hardships is the mismatch in the demand and supply of manpower. Thus the government is developing a manpower policy to relieve the situation. To suggest policy implications, this study analyzes the demand and supply of Information Security manpower in the systematic and behavioral point of views. Using System Dynamics approach we formulate a model to analyze the demand and supply of Information Security manpower. Finally we simulate the model and interpret the results.

• Korean System Dynamics Review
• /
• v.3 no.1
• /
• pp.79-104
• /
• 2002

A system dynamics project is going on for forecasting automobile market in Korea. The project is made up of three stages, and the first stage has been wrapped up. As the first attempt, most efforts have been focused on the sound foundation rather than the exact forecast. The model consists of three sectors; the supply sector, the demand sector, and the population sector. The supply sector is a simple stock and flow diagrams representing the supply capacities of all automobile types. The major effort is made on the demand sector and the population sector. The demands are divided into three categories; replacement demands, new demands, and additional demands. The model applies “one car per person" concept, and assumes there will be no additional demands for a while. The replacement demands are calculated based on a simple stock and flow diagram. The new demands are calculated via Bass models; each bass model represents a diffusion for each age group. The population is divided into 101 age groups (age 0 to age 100). The model has been calibrated with past 10 year data (1990 - 1999), and tested for the next two years (2000-2001). The results ware acceptable, although a fine tuning is required. Now the second stage is going on, and most of efforts are made how to incorporate the economic and cultural factors.