• Nuclear Engineering and Technology
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• v.27 no.3
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• pp.336-343
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• 1995

The Self Tuning Regulator(STR) method which is an approach of adaptive control theory, is ap-plied to design the fully automatic power controller of the nonlinear reactor model. The adaptive control represent a proper approach to design the suboptimal controller for nonlinear, time-varying stochastic systems. The control system is based on a third­order linear model with unknown, time-varying parameters. The updating of the parameter estimates is achieved by the recursive extended least square method with a variable forgetting factor. Based on the estimated parameters, the output (average coolant temperature) is predicted one-step ahead. And then, a weighted one-step ahead controller is designed so that the difference between the output and the desired output is minimized and the variation of the control rod position is small. Also, an integral action is added in order to remove the steady­state error. A nonlinear M plant model was used to simulate the proposed controller of reactor power which covers a wide operating range. From the simulation result, the performances of this controller for ramp input (increase or decrease) are proved to be successful. However, for step input this controller leaves something to be desired.

• Journal of the Korean Institute of Intelligent Systems
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• v.6 no.2
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• pp.3-12
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• 1996

Sliding mode controller(SMC) is a simple but powerful nonlinear controller, because it guarantees the stability and the robustness. However, it leads to the high frequency chattering of the control input. Although the phenomenon can be avoided by introducing a thin boundary layer to the sliding surface, the method results in a steady state: error proportional to the boundary layer thickness. In this paper, we proposed a new sliding mode controller with self-tuning the thickness of a boundary layer. It uses a fuzzy rule base for tuning the thickness of a boundary layer. That is, the thickness is increased to some degree to reject a discontinuous control input at the initial state and then it is decreased as the states approaches to the steady states for improving the tracking performance. In order to assure the control performance, we perf'ormed the computer simulation using an inverted pendulum system as a controlled plant.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.5
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• pp.464-470
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• 2010

The integrity of the industrial equipment in use under high temperature and high pressure must be assessed by regularly measuring the degraded mechanical properties during service time. In order to nondestructively monitor the degraded mechanical properties of industrial equipment, a measuring method of the reversible permeability(RP) using surface type probe is presented. The method for measuring the RP is based on that RP is the differential value of hysteresis loop. The RP is exactly the foundation hatmonics induced in a detecting coil measured by lock-in amplifier tuned to a frequency of the alternating perturbing magnetic field. The peak of RP is measured around the coercive force. Steel material used in this work was 12Cr ferritic heat resisting steel. The eleven kinds of samples aged during different times under same temperature ($700^{\circ}C$) were prepared. Peak interval of reversible permeability(PIRP), Vickers hardness, and tensile strength measured for the aged samples decreased abruptly for short aging time (below 500 h), but the change became small at a long aging time. Vickers hardness and tensile strength linearly decreased as RIRP decreased, so the degraded mechanical properties of 12Cr ferritic heat resisting steel could be nondestructively evaluated by measuring RIRP.

• Korea journal of population studies
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• v.28 no.2
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• pp.97-129
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• 2005

Korean society recently witnesses a rapid lllcrease of suicide across all ages. In particular, suicide in old ages jumps up ill a very unexpected way. Furthermore, the order of suicide in the cause of death across all ages is becoming higher and higher in Korea. This study provides details of suicide that occurs in Korean society with the comparison to that of Japan at the descriptive level. It is not well known why suicide in Korean surges recently. Several previous research show the possibility that surging suicide is closely related to the worsened economic conditions especially since the economic crisis in 1997. They adopt economic growth, unemployment rate, income distribution, household finance index as economic indicators in their research. This study also adopts those indicators and conducts a correlation analysis in two periods, 1990-1997 and 1998-2004. It is found that there is no correlation between economic indicators and suicide in the period of 1990-1997. On the other hand, there is a very strong correlation between income distribution and suicide in the period of 1998-2004. Other economic indicators except income distribution does not have any significant correlation with suicide. This finding suggests that currently increasing suicide in Korea may be a result of economic polarization, which has been worsened since the economic crisis in 1997.

• Industry Promotion Research
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• v.5 no.4
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• pp.55-61
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• 2020

In conducting school violence counseling to solve school violence, this study studied the use of school violence counseling to solve school violence by forming a correct peer relationship. Through this study, we can see that peer relations are an important factor in preventing school violence in school violence counseling. The findings are as follows. First, school violence counseling should first protect and heal victims. The primary goal of school violence counseling should begin with consideration for the victims and be placed on the continuation of the victim's right peer relationship. That's how important peer relationships are. Second, not only victims of school violence counseling, but also perpetrators should be included in the list of counsels. In other words, there may be many cases where counseling is usually focused only on the victim. Therefore, the peer relationship can continue even after school violence, so customized counseling is needed not only for victims but also for perpetrators. Third, for school violence counseling, the recovery of peer relations and insight into life are important. Therefore, the focus should be on self-reflection and the restoration of relations between the parties, not on a disciplined or disciplined, controlled perspective. Fourth, we should recognize the importance of peer relations in school violence and activate the 'old counseling program'. Therefore, school violence counselors should optimize their programs by reflecting on-site needs so that they can act as emotional facilitators, problem solvers, and empathic cultural promoters in their roles. In conclusion, school violence counseling should basically be involved in peer relationships. School violence counseling should develop and implement programs focusing on the formation of proper peer relations in order to eradicate school violence.

• Cartoon and Animation Studies
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• s.34
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• pp.167-195
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• 2014

A handwritten poster named "How are you, really?" appeared on December 10, 2013. And other handwritten posters sympathizing with it followed in places and are on everyone's lips hotly through internet and SNS. Such a social phenomenon is delivered to readers as a form of article in different meanings according to the viewpoint of each press. It is also delivered to readers as a material for delivering a meaning of a specific case in four panel comics strips and satirical cartoon of newspaper. This is because that comic strips of the press are now having a power to enlighten readers on the key point of a case easily and intuitively together with catharsis from the position of meditating the world. Notwithstanding differences depending on the viewpoints of the press or cartoonist, four panel comics strips and satirical cartoon on the newspaper are fulfilling their social role having their own voice. Of the genres of comic strips, social role of the comics of the press can be divided largely into two things. First, they actively intervene in social phenomena. In other words, comics of the press make their position and insistence on social phenomena clearly by exaggeration and emphasis. Second, they persuade or enlighten readers by concrete directions, which means that comics of the press make reader with similar viewpoint emphasize by delivering a clear message. This study aims to assert that comic strips are the most important medium with social role and responsibility. As part of studies on the social role of comics, this study wish that comic strips can be able to deviate from vicious circle of being socially condemned for reason of negative portion.

• Journal of Korean Home Economics Education Association
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• v.21 no.2
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• pp.127-138
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• 2009

The purpose of this study was to find out the usage of animation and its relation to the social values and clothing behaviour of adolescents. A survey was conducted in four different high schools in the metropolitan area (Seoul) and 187copies were analyzed by SPSS 12.0 package. The results were as follows; First, According to Usage survey, a number of adolescents watched animations mainly through the internet and 39% of them used the internet $2{\sim}3$ times a week. The most watched genre of animation was action/science-fiction but some differences were observed between male students and female students. Male students enjoyed action/science-fiction, comedy and drama/romance, whereas female students enjoyed drama/romance, action/science-fiction and comedy in the decreasing order. Second, It was found that the favorite genre of animation by adolescents had influence on their community mind and materialism. The most significant genre affectingcommunity life was drama/romance and the one affecting materialism of adolescents was action/science-fiction. Third, Materialism had a significant influence on clothing conformity and the next was community mind. Only materialism proved to be a significant variable affecting fashion followers. In conclusion, the results of this study showed that the adolescents' community life and materialism were significantly influenced by their favorite genre of the animation, and their social values were related to their clothing behaviors.

• Korean Journal of Applied Biomechanics
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• v.19 no.2
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• pp.205-215
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• 2009

The purpose of this study is to investigate alterations of pregnant gait by means of 3 different treads of stairs. 9 subjects(body masses; $59.41{\pm}7.49$, $64.03{\pm}6.65$, $67.26{\pm}7.58$, heights; $160.50{\pm}6.35$ ages; $31.22{\pm}2.99$; parity; $1.67{\pm}0.71$) participated in three experiments that were divided by physiological symptoms(the early(0-15 weeks), middle(16-27 weeks) and last(18-39 weeks), and walked at self-selected pace on 4 staircases 3 trials. As extending the pregnancy period, cadence was shorter but cycle time was longer more and more and the difference of maximum and minmum moments between right and left knee joint moment was smaller. With the treads of stair decent lengthening, speed and stride lengths were increased. As extending the treads of stair decent, joint moments of both feet were particular traits, hip joint was asymmetric but joint moments of knee and ankle were symmetric. These findings may account for relation between the treads of stair and moments and suggest that women may adapt their gait to maximize stability and to control gait motion for themselves in pregnant women.

• Journal of Convergence for Information Technology
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• v.11 no.9
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• pp.145-156
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• 2021

This study is aimed to improve the youth theft prevention program with rationality and practicality, based on the needs of practitioners who conduct these programs in fields. The survey questionnaire was prepared based on previous researches, and the survey was conducted on 72 probation officers and education instructors nationwide running a youth theft prevention program. As a result, practitioners reported the lack of self-control and high impulsivity as the main characteristics of the theft delinquent adolescents. And they recognized peer alignment and family problems as the causes of theft. As for the contents of the program, they reported that recidivism prevention skills such as understanding psychological problems, peer relationships, raising a sense of law compliance, anger, impulse control, dealing with negative emotions, and finding alternative behaviors, as well as moral development, are necessary. These results indicate that multi-dimensional interventions such as individuals, families, and peers are needed to prevent recidivism of juvenile theft. Implications of these results, future research directions, and limitations and significance of the study were discussed.

• Journal of the Korean Chemical Society
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• v.60 no.3
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• pp.203-214
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• 2016

The purpose of this study was to investigate brain activation pattern and functional connectivity during convergence thinking based creative problem solving and chemistry problem solving to identify characteristic convergence thinking that is backbone of creative problem solving using functional magnetic resonance imaging(fMRI). A fMRI paradaigm inducing convergence thinking and chemistry problem solving was developed and adjusted on 17 highschool students, and brain activation image during task was analyzed. According to the results, superior frontal gyrus, middle frontal gyrus, inferior frontal gyrus, medial frontal gyrus, cingulate gyrus, precuneus and caudate nucleus body in left hemisphere and cuneus and caudate nucleus body in right hemisphere were significantly activated during convergence thinking. The other hand, middle frontal gyrus, medial frontal gyrus and caudate nucleus in left hemisphere and middle frontal gyrus, lingual gyrus, caudate nucleus, thalamus and culmen of cerebellum in right hemisphere were significantly activated during chemistry problem solving. As results of analysis functional connectivity, all of areas activated during convergence thinking were functionaly connected, whereas scanty connectivity of chemistry problem solving between right middle frontal gyrus, bilateral nucleus caudate tail and culmen. The results show that logical thinking, working memory, planning, imaging, languge based thinking and learning motivation were induced during convergence thinking and these functions and regions were synchronized intimately. Whereas, logical thinking and inducing learning motivation functioning during chemistry problem solving were not synchronized. These results provide concrete information about convergence thinking.