• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.1
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• pp.30-39
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• 2000

In order to linearize the nonlinear systems, two different methods(i.e. state coordinate change and feedback) are usually used. In this paper, we consider the multi-input discrete-time nonlinear systems and obtain the necessary and sufficient conditions for both the linearization problem by state-coordinate change and the feedback linearization problem. The way of finding state coordinate change and state feedback which linearize the given system is also given in the proof.

• Korean Journal of Community Nutrition
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• v.13 no.5
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• pp.653-662
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• 2008

This study has been performed to analyze nutrition knowledge, dietary self-efficacy and eating habits of the elementary- and middle- school students (n = 342) according to student's stage of regular breakfast or exercise. Middle school students had higher nutrition knowledge than primary school students. Total dietary self-efficacy and dietary habit scores were not different by school year and gender. Nutrition knowledge, dietary self-efficacy and dietary habit scores were positively correlated each other. By the stage of regular breakfast, the pre-contemplation stage comprised 13.6%, contemplation 2.1%, preparation 15.7%, action 11.5% and maintenance stage 59.1%. By the stage of regular exercise, the pre-contemplation stage comprised 20.9%, contemplation 7.3%, preparation 45.6%, action 9.8% and maintenance stage 16.4%. According to the stage of change, movement from the pre-contemplation and contemplation to upper stage increased the dietary self-efficacy score. Dietary habit score increased significantly across the five stages of changes. The results of this study indicate differences in stages of changes in breakfast intake and regular exercise and indicate the need for taking these phases of change into account in nutrition education.

• Journal of the Korean School Mathematics Society
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• v.3 no.2
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• pp.111-122
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• 2000

This study is focused on vocational high school students who feel hardly interested in mathematics and are considered to have very limited basic scholastic ability. It analyzes the data obtained by applying the material, extracted from the Internet and literature to school classes from March to July, for the purposes of improving the degree of scholastic achievement on the basis of the fact that interest induced learning materials were developed and applied to the students to bring about their motivation resulting in a positive change in understanding and attitudes to mathematics. According to the result of the analysis, the level of students' scholastic ability of both the comparative class and the experimental class were too low to become interested in mathematics. However, the experimental class students seemed to feel familiar to the learning materials rather than reluctant, and it appeared that their interest and behavior of learning began to change gradually in an extent. In addition to that, as an aspect of scholastic achievement there was not considerable difference between the two classes, but as time went, some valuable changes were found. Unfortunately, the size of group of the research was small and the period of the experimental classes was not extensively long, and therefore the same result might not occur in other groups. However, it is believed that in class-time, educating students by putting in learning materials bringing about relevant motivation to the class, will lead them to become interested in mathematics, and change their attitudes and understanding of mathematics. After all, scholastic achievement will be effective.

• School Mathematics
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• v.18 no.1
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• pp.43-59
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• 2016

The purpose of this qualitative case study is to investigate differences among two gifted middle school students emerging through the process of algebra word problem solving from the covariational perspective. We collected the data from four middle school students participating in the mentorship program for gifted students of mathematics and found out differences between Junghee and Donghee in solving problems involving varying rates of change. This study focuses on their actions to solve and to generalize the problems situations involving constant and varying rates of change. The results indicate that their covariational reasoning played a significant role in their algebra word problem solving.

• Steel and Composite Structures
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• v.32 no.4
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• pp.467-478
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• 2019

Running safety and ride comfort of high speed railway largely depend on the track geometry that is dependent on the bridge deformation. This study presents a theoretical study on mapping the bridge vertical deformations to the change of track geometry. Analytical formulae are derived through the theoretical analysis to quantify the track geometry change, and validated against the finite element analysis and experimental data. Based on the theoretical formulae, parametric studies are conducted to evaluate the effects of key parameters on the track geometry of a high speed railway. The results show that the derived formulae provide reasonable prediction of the track geometry change under various bridge vertical deformations. The rail deflection increases with the magnitude of bridge pier settlement and vertical girder fault. Increasing the stiffness of the fasteners or mortar layer tends to cause a steep rail deformation curve, which is undesired for the running safety and ride comfort of high-speed railway.

• The Journal of Sustainable Design and Educational Environment Research
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• v.10 no.2
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• pp.46-60
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• 2011

Nowadays, the change of the social structure such as the elderly society and the broken traditional family conception is progressing rapidly. The social change produced a lot of problems, and the welfare from among these is the urgent problem. The welfare for the aged is very important problem in an aging society. The changes of industrial and economic structures also caused the increase of double-income families. The numbers of schoolchildren decreased rapidly because of the low birth and elderly society. So, many idle spaces of existing school facilities have emerged, and these left spaces is being blamed for the fiscal waste. If these idle spaces were used for the welfare-facilities, it will be of assistant to solve the problem about welfare and use the school facilities effectively. And then, the big profit from these enterprises can be used for the better welfare for education.

• Journal of the Korean Society of School Health
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• v.4 no.2
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• pp.159-175
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• 1991

This study was carried out with 2,195 boy and girl middle school students in Inchon to examine environmental elements which may change vision and cause shortsightedness, and also to find out common knowledge of eye health. Its results are as follows. 1) As school year goes up, the normal eye sighted diminish but the visually handicapped regardless of left and right eyes increase. 2) Among weak sighted students below 0.9, boys are 42.2% and girls are 55.3%, the latter are larger by 13.1 %. Vision weakens rapidly especially for third year girl students. 3) Environmental, individual, everyday life elements which cause shortsightedness are studied, (1) environmental elements; illumination in watching TV and studying (2) individual elements; distance from TV and books, posture in studying (3) everyday life elements; hour of watching TV, hour of using game tools average, hour of studying 4) Knowledge of eye health is generally poor without regard to sex and wearing glasses. So adolescent students are in advance educated proper eye care to prevent shortsighted elements.

• International Journal of Advanced Culture Technology
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• v.10 no.3
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• pp.63-70
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• 2022

This study is to investigate that population change as a result of the decline in population has a correlation with a decrease in crime, with the change in the demographic composition by comparing with two models: model with growth in population and one with the decline in population. We collected demographic data for all cities in Korea from the 2010 Census to 2020 offered by the Korean Statistical Information Service, with crime data comprising serious reported crime events from the Korean Nation Police Agency through requesting data related to the total number of crimes at the same as the period of demographic data. This study can identify the impacts of demographic changes as a result of population change on crime change through a comparative analysis between areas with population growth and ones with population decline. We can confirm that there are differences in determinants of crime between areas with population increase and one with population decrease from the analysis of the impact of demographic change as a result of population change on crime change.

• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.22-35
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• 2016

Global climate change could have an impact on hydrological process of a watershed and result in problems with future water supply by influencing the recharge process into the aquifer. This study aims to assess the change of groundwater recharge rate by climate change and to predict the sustainability of groundwater resource in Pyoseon watershed, Jeju Island. For the prediction, the groundwater recharge rate of the study area was estimated based on two future climate scenarios (RCP 4.5, RCP 8.5) by using the Soil Water Balance (SWB) computer code. The calculated groundwater recharge rate was used for groundwater flow simulation and the change of groundwater level according to the climate change was predicted using a numerical simulation program (FEFLOW 6.1). The average recharge rate from 2020 to 2100 was predicted to decrease by 10~12% compared to the current situation (1990~2015) while the evapotranspiration and the direct runoff rate would increase at both climate scenarios. The decrease in groundwater recharge rate due to the climate change results in the decline of groundwater level. In some monitoring wells, the predicted mean groundwater level at the year of the lowest water level was estimated to be lower by 60~70 m than the current situation. The model also predicted that temporal fluctuation of groundwater recharge, runoff and evapotranspiration would become more severe as a result of climate change, making the sustainable management of water resource more challenging in the future. Our study results demonstrate that the future availability of water resources highly depends on climate change. Thus, intensive studies on climate changes and water resources should be performed based on the sufficient data, advanced climate change scenarios, and improved modeling methodology.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.6
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• pp.643-647
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• 2007

Purpose: The purpose of study was to investigate the correlationship between lip canting change and occlusal canting change after bimaxillary orthognathic surgery, and the ratio of lip canting change and occlusal canting change after the surgery. Patients and methods: The subjects for this study was obtained from a group of 25 patients who took bimaxillary orthognathic surgery for occlusal canting correction at the Department of the Oral and Maxillofacial Surgery, Samsung Medical Center in Seoul, Korea between January 2000 and December 2005 and a patient's chart had to contain a resting frontal facial photograph in natural head position and a corresponding PA cephalogram in occlusion on the same day before the surgery and post-op 6 months later. The lip canting change was assessed with the angle each labial commissure and the bipupilary reference line. And, the occlusal caning change in the frontal plane was assessed with the angle between the each maxillary first molar occulasal surface and the bi-frontozygomatic suture reference line. Results: In angular measurement, average occlusal canting change was $3.09^{\circ}$ and standard deviation was $1.05^{\circ}$, average lip canting change was $1.56^{\circ}$ and standard deviation was $1.05^{\circ}$. In linear measurement, average occlusal canting change was 2.41mm and standard deviation was 2.75mm, average lip canting change was 1.18mm and standard deviation was 0.43mm. Lip canting correction ration to occlusal canting correction was 51.5(${\pm}8.4$)% in angular measurement and 48.8(${\pm}9.1$)% in linear measurement. Under Pearson's correlation analysis, Pearson's correlation coefficient was 0.869 in angular measurement and 0.887 in linear measurement(p-value < 0.01). High correlationship was shown between occlusal canting change and lip canting change. Conclusion: First, Bimaxillary orthognathic surgery can correct lip canting as well as occlusal canting. Second, The average amount of lip canting correction is $51.5{\pm}8.4%,\;48.8{\pm}9.1%$ of occlusal canting correction in the study.