• Imaging Science in Dentistry
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• v.47 no.1
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• pp.1-9
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• 2017

Purpose: This retrospective study aimed to evaluate the nasopharyngeal and oropharyngeal dimensions of individuals with skeletal class II, division 1 and division 2 patterns during the pre-peak, peak, and post-peak growth periods for comparison with a skeletal class I control group. Materials and Methods: Totally 124 lateral cephalograms (47 for skeletal class I; 45 for skeletal class II, division 1; and 32 for skeletal class II, division 2) in pre-peak, peak, and post-peak growth periods were selected from the department archives. Thirteen landmarks, 4 angular and 4 linear measurements, and 4 proportional calculations were obtained. The ANOVA and Duncan test were applied to compare the differences among the study groups during the growth periods. Results: Statistically significant differences were found between the skeletal class II, division 2 group and other groups for the gonion-gnathion/sella-nasion angle. The sella-nasion-B-point angle was different among the groups, while the A-point-nasion-B-point angle was significantly different for all 3 groups. The nasopharyngeal airway space showed a statistically significant difference among the groups throughout the growth periods. The interaction among the growth periods and study groups was statistically significant regarding the upper oropharyngeal airway space measurement. The lower oropharyngeal airway space measurement showed a statistically significant difference among the groups, with the smallest dimension observed in the skeletal class II, division 2 group. Conclusion: The naso-oropharyngeal airway dimensions showed a statistically significant difference among the class II, division 1; class II, division 2; and class I groups during different growth periods.

• Journal of Electrical Engineering and Technology
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• v.4 no.2
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• pp.292-300
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• 2009

This paper considers a robust adaptive stabilization problem for a class of uncertain nonlinear systems which include an unknown virtual control coefficient, an unknown constant parameter, and a time-varying disturbance whose bound is unknown, We propose a new estimator for an un-known virtual control coefficient and present a robust adaptive backstepping design procedure which results in a smooth state feedback control law, a new two-dimensional parameter update law, and a $C^1$ Lyapunov function which is positive definite and proper.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.3
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• pp.98-109
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• 2000

A new PC-based Engine Control system (ECS) is developed using an object oriented programming method. This system provides more convenient environment for engine tests, easier user interface and extended functions. A Windows-based ECS software is developed with class, and the class structure is built on encapsulation and abstraction. The closed-loop engine control scheme can be easily constructed by using dynamic link library and multitasking. This means that a user can perform desired experiments without clear knowledge of the hardware structure of the ECS. Also this system allows a user to individually control the ignition and fuel injection for each cylinder in a simple manner such as through a keyboard/mouse or in a real-time operation from a closed-loop control program.

• International Journal of Control, Automation, and Systems
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• v.6 no.1
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• pp.35-43
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• 2008

The control of underactuated mechanical system is very complex for the loss of its control inputs. The model of underactuated mechanical systems in a potential field is built with Lagrangian method and its structural properties are analyzed in detail. A genetic algorithm (GA)based stable control approach is proposed for the class of under actuated mechanical systems. The Lyapunov stability theory and system properties are utilized to guarantee the system stability to its equilibrium. The real-valued GA is used to adjust the controller parameters to improve the system performance. This approach is applied to the underactuated double-pendulum-type overhead crane and the simulation results illustrate the complex system dynamics and the validity of the proposed control algorithm.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.4
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• pp.757-765
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• 2013

The purpose of this study is to examine the effects of peer tutoring on students' achievement and learning satisfaction in a liberal computer class at university level. Traditional teaching method was applied for the control group consisting 55 students for 8 weeks. The experimental group containing 44 students was instructed using both traditional teaching method and peer tutoring. According to the results of diagnosed test, the experimental group was divided into heterogeneous ability group of 3 or 4. The tutor training was provided a week in advance of the class and the students played a role of a tutor and tutee by taking turns. The results showed no significant differences between the two groups on academic achievement; however, in terms of students' learning satisfaction, it displayed a wider range of results. The learning satisfaction data from the experimental group showed a much higher level than that of the control group. It is predicted that the amount of class hours of a week, the quality of the lecture and the application of peer tutoring affect the students' academic achievement. It is suggested that subsequent research on peer tutoring will allow for more in-depth study in this field.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.6
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• pp.573-578
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• 2011

We propose a switching-based adaptive state feedback controller for a class of nonlinear systems that have uncertain nonlinearity. The base of the proposed conditions on the nonlinearity is the feedforward form, then it is extended via a nonlinear function containing all the states and the control input. As a result, more generalized systems containing feedforward and nonfeedforward terms are allowed as long as the ratio condition of the nonlinear function is satisfied. Moreover, the information on the growth rate of nonlinearity is not required a priori in our control scheme.

• Journal of the Korea Society of Computer and Information
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• v.27 no.8
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• pp.253-261
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• 2022

In this study, the educational effect were sought to be identified after developing and applying project learning for the artificial intelligence based liberal arts education for the non-computer majors. A paired-sample t-test was performed within each group to determine the extent of improvement in the learning flow and artificial intelligence efficacy in the experimental and control groups. After class, an independent sample t-test was performed to examine the statistical effects of pre-test and post-test on the learning flow and artificial intelligence efficacy in the experimental and control groups. The experimental group and control group demonstrated significant improvements in the learning flow and artificial intelligence efficacy before and after class, each respectively. There was no statistically significant difference in the learning flow between the experimental group for which the project learning method was applied and the control group for which only theory and practice were conducted in the artificial intelligence class. It was also confirmed that the experimental group for which the project learning method was applied improved the efficacy of artificial intelligence to a significant level compared to the control group which only proceeded with theory and practice.

• The Mathematical Education
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• v.44 no.3 s.110
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• pp.435-456
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• 2005

This research aims to analyse implementation effects of the Real mathematics Education(RME) in the high school probability and statistics For this aim, two research questions are estabilished as fellows. (1) Is there any improvement of mathematical achievement in the class by RME's lecture than in the class by the mathematics text's lecture ? (2) Is there any improvement of mathematisation level in the class by RME's lecture than in the class by the mathematics text's lecture ? Before answering the above research questions, RME.`s lecture notes and ordinary lecture notes are developed based on the learning principles of the RME and mathematics textbook respectively. Two classes are randomly chosen from a high school located at midium size city and assigned as the experimental group and the control group respectively. The 20 hours of the RME's lecture notes is administerd to the experimental group and the 20 hours of the odinary lecture notes is administerd to the control group. It is shown that the class by RME's lecture is more effective in both of the mathematical achievement and the mathematisation activity than the class by the ordinary lecture. Hence, it is urged from the result of this research that RME's context will be developed and the RME's lecture will be implemented in the other field of high school mathematics.

• The Journal of Internal Korean Medicine
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• v.21 no.3
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• pp.433-441
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• 2000

Objective : To analyze the effects of Yukmijihwang-tang, Taeksa-tang, Silbi-um on mesangial cell proliferation, fibronectin synthesis and MHC-class II expression. Methods : Laboratory studies were performed with the method of surface enzyme immunoassays or flow cytometry after addition of peripheral blood mononuclear cells(PBMC) supernatants treated with medications using the cultured human mesangial cells. Results : 1. Silbi-um produces more suppressive effect than control group and hydrocortisone group on the mesangial cell proliferation. In Yukmijihwang-tang, Taeksa-tang and Silbi-um, mesangial cell proliferation significantly decreased than in hydrocortisone group 2. In the 'without fetal bovine serum' study, Yukmijihwang-tang take more suppressive effect than Control group on the fibronectin synthesis. In the 'with fetal bovine serum' study, Yukmijihwang-tang, Taeksa-tang, Silbi-um all have suppressive effect, but it hasn' t any statistical significance. 3. Yukmijihwang-tang, Taeksa-tang, Silbi-um all have a suppressive effect on the MHC-class II expression. Conclusions : Herb medicine generally show a suppressive effect on the suppression of the mesangial cell proliferation, fibronectin synthesis and MHC-class II expression.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.744-750
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• 2001

In now a days, the concern to environment and energy saving problem is increased worldly. So many countries are developing the wind power system as clean energy system. In our country, Cheju local government has the plan of the Cheju Island wind farm and 600kW class 2 wind turbines, 660kW class 2 turbines, 225kW class 1 turbine and 750kW class 2 turbines has been operated at Hangwon. In this paper the field operation data of the wind turbines was analyzed and was compared with the characteristics & performance of each turbines. As the results, we would find the possibility of wind turbine in domestic and suggest the direction of developing technology.