• Korean Journal of Health Education and Promotion
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• v.17 no.2
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• pp.17-33
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• 2000

The aim of this study is having the status, knowledge and attitude of the high school attendees toward smoking be analyzed, helping to make effective health education methods to diminish adolescent smoking habits. The field self-questionnaire investigation has been performed from Oct 10th through 23rd in 1999. The whole 427 cases were distributed to 1st and 2nd grade students of randomly selected men's high school in Seoul. And 414 cases (97%) were finally selected for analysis after exclusion of cases with insufficient information. The main contents of questionnaire are composed of several sectors; the general characteristics of the interviewees, the relationship with parents, the life style and the peer relationship in school. And smoking-related characteristics are taken into consideration, too. The major findings of the study are as follows: The smoking/non-smoking related factors are, in socio-demographical terms, the grade, average spending per month of the interviewees. And the degree of satisfactory relationship with parents is significant on smoking behavior. The higher, the degree of satisfaction on school life and relationship with designated teacher, the more chances of non-smoking habit. Poor academic grades and peer group dependability of interviewees cause higher smoking habit rate in other way. The self-interviewees grade and cohabitation with parents are also significant on both the attitude toward smoking habit and the knowledge on smoking statistically. The academic history and vocations of the parents and the academic grades of interviewees are also effective variables, but don't make any gap between groups knowledge on smoking. Smoking groups used to have positive attitude toward smoking habit. Both the attitude and knowledge on smoking by the consideration of Quit-smoking have statistically significance. The groups which have negative attitude and high knowledge on smoking quit-smoking into consideration. And the primary cause of quit-smoking is on health by smoking. Depression, stress, adult smoking in the house, peer group pressure, cigarettes advertisements on papers and magazines and smoking scenes on TV have positive correlation on forming smoking habit (p〈0.001) But the knowledge on diseases triggered by smoking has negative correlation on forming smoking habit. (p〈0.05, p〈0.001). Social factors as monthly spending, relationship and communication with parents, the degree of satisfaction in school life, academic grades and student-teacher relationship have crucial negative correlation on smoking habit. That is to say, the higher, the monthly spending is, the worse, the relationship with parents and teachers is, the lower, the academic grades of the student is, the percentage of the interviewees who have smoking habit seems to get higher.

• (The)Korea Educational Review
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• v.24 no.1
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• pp.199-225
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• 2018

Using the 3rd to the 6th wave data from the Korean Children and Youth Panel Survey(KCYPS), we examined the effects of academic characteristics and social relations on the trajectories of the life satisfaction among adolescents. OLS results showed that male students were more satisfied with their lives than female students in the 3rd grade of middle school. As academic characteristics, academic achievement and the level of class adjustment improved life satisfaction but the amount of learning time spent had a negative effect on life satisfaction. However, the effect of academic achievement lost its statistical significance after including variables of social relations. Relationships with parents, teachers, and friends had positive effects on life satisfaction. The longitudinal analysis using the fixed effect estimation also showed a similar result of the associations among the variables to that in the OLS analysis. The life satisfaction gap between male and female students narrowed over time from the 3rd grade of middle school to the 2nd grade of high school. The effects of relationships with parents and friends showed significant effects on both female and male students, but the relationship with their teachers was significant only for female students. Based on the results, we discussed the issues of Korean education related to the life satisfaction among adolescents.

• Journal of Korea Entertainment Industry Association
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• v.15 no.3
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• pp.171-182
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• 2021

This study analyzed the factors influencing the satisfaction of school students in Covid-19. The subjects of the study were surveyed in all 5th-6th grade of elementary school students, 1st-3rd grade of middle school, and 1st and 2nd grade of high school students in G metropolitan city. A total of 13,672 students participated in the survey, of which 13,613 were used for final data analysis. A hierarchical regression analysis of factors affecting students' life satisfaction showed that 22.2% of school life factors, 4.7% of home life factors, and 10.7% of daily stressors. The most influential factor in Covid-19 was home life satisfaction. Next was appearance stress for elementary school students and academic stress for middle and high school students. This can be seen as a result of Covid-19, which increased non-face-to-face classes and increased time for students to spend at home, which led to a greater impact on students' satisfaction in life. Nevertheless, middle and high school students can still see that academic stress has a significant impact on life satisfaction. Through this, it is necessary to support students to facilitate relationships, communication, studies, and leisure at home in the context of Corona 19. Especially, various educational policies must be accompanied so that the educational gap due to non-face-to-face classes does not deepen depending on the family environment.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2182-2186
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• 2003

This paper presents the differential type resonant accelerometer (DRXL) and its performance test results. The DRXL is the INS grade, surface micro-machined sensor. The proposed DRXL device produces a differential digital output upon an applied acceleration, and the principle is a gap-dependent electrical stiffness variation of the electrostatic resonator with torsion beam structures. Using this new operating concept, we designed, fabricated and tested the proposed device. The final device was fabricated by using the wafer level vacuum packaging process. To test the performance of the DRXL, a nonlinear self-oscillation loop is designed using describing function technique. The oscillation loop is implemented using discrete electronic elements. The performance test of the DRXL shows that the sensitivity of the accelerometer is 12 Hz/g and its long term bias stability is about $2mg(1{\sigma})$. The turn on repeatability, bandwidth, and dynamic range are 4.38 mg, 100 Hz, and ${\pm}\;70g$, respectively.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.6
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• pp.634-640
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• 2009

The plate manufacturing processes are composed of the reheating furnace, finishing mill, cooling process and hot leveling. The finishing rolling mill (FM) as a reversing mill has produced the plate steel through multiple pass rolling. The automatic gauge control (AGC) is employed to maintain the thickness tolerance. The high grade products are forming greater parts of the manufacturing and customers are requiring strict thickness margin. For this reason, the advanced AGC method is required instead of the conventional AGC based on the PI control. To overcome the slow response performance of the conventional AGC and the thickness measurement delay, a fuzzy AGC based on the thickness deviation and its trend is proposed in this paper. An embedded controller with the fuzzy AGC has been developed and implemented at the plate mill in POSCO. The fuzzy AGC has dynamically controlled the roll gap in real time with the programmable logic controller (PLC). On line tests have been performed for the general and TMCP products. As the results, the thickness deviation range (maximum - minimum of the inner plate) is averagely from 0.3 to 0.1 mm over the full length. The fuzzy AGC has improved thickness deviation and completely satisfied customer needs.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.1
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• pp.58-66
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• 2005

Inertial-grade vertical-type and lateral-type differential resonant accelerometers (DRXLs) are designed, fabricated using one process and tested for navigational applications. The accelerometers consist of an out-of-plane (for z-axis) accelerometer and in-plane (for x, y-axes) accelerometers. The sensing principle of the accelerometer is based on gap-sensitive electrostatic stiffness changing effect. It says that the natural frequency of the accelerometer can be changed according to an electrostatic force on the proof mass of the accelerometer. The out-of-plane resonant accelerometer shows bias stability of $2.5{\mu}g$, sensitivity of 70 Hz/g and bandwidth of 100 Hz at resonant frequency of 12 kHz. The in-plane resonant accelerometer shows bias stability of $5.2{\mu}g$, sensitivity of 128 Hz/g and bandwidth of 110 Hz at resonant frequency of 23.4 kHz. The measured performances of two accelerometers are suitable for an application of inertial navigation.

• Journal of Korean Society of Water and Wastewater
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• v.9 no.4
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• pp.73-86
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• 1995

The propriety of the numerical model application was examined on Paldang resevoir and its inflow tributaries located in the center of the Korean peninsula and the long term water quality forecast of the oxygen profile was carried out in this syduy. The input data of the model was the capacity of the reservoir, catchment area, percolation, diffusion rate, vertical mixing rate, dissolution rate from the bottom of the reservoir, outflow of the resevoir, water quality measurement and meteorology data of the drainage basin, and the output result was the annual estimation value of the dissolved oxygen concentration and the biochemical oxygen demand. The modeling method is based on the measured or calculated boundary condition dividing the water area into several blocks from the macorscopic aspect and considering the mass balance in these blocks. As the result of the water quality forecast, it was expected that the water quality in Northern Han River and Paldang reservoir would maintain the recent level, but that the water quality in the Southern Han River and its inflow tributary would worsen below the grade 4 of the life environmental standard from around 2000 owing to the decrease of DO concentration and the increase of BOD concentration.

• Laser Solutions
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• v.13 no.3
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• pp.19-26
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• 2010

In this study, fundamental experiment was conducted with various strength of UHSS (Ultra High Strength Steel) by $CO_2$ laser. And then, butt and lap joint laser welding with boron alloyed steel and Al-Si coated boron alloy steel have been done by changing laser beam feature, existence of gap and existence of coating layer to know welding characteristics of those materials. As a result, in case of fundamental experiment with various strength steel, hardening was found in the weld metal of all tested materials and softening was found at the heat affected zone of SGAFC 1180. In case of laser butt welding of UHSS, mechanical properties was improved by using small laser beam diameter and Al-Si coating layer caused fracture of weld metal. In case of laser lap welding of UHSS, Al-Si coating layer resulted in formation of intermetallic compound at the fusion boundary where fracture occurred. Al-Si coating layer caused lowering mechanical properties of weld metal.

• Journal of Mechanical Science and Technology
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• v.16 no.6
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• pp.785-798
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• 2002

A reliable analytic model that predicts the surface profile of the exit cross section of workpiece in round-oval (or oval-round) pass sequence is established. The presented model does not require any plasticity theory but needs the only geometric information on workpiece and roll groove. Formulation is based on the linear interpolation of the radius of curvature of an incoming workpiece and that of roll groove in the roll axis direction when the maximum spread of workpiece is known beforehand. The validity of the analytic model is examined by hot rod rolling experiment with the roll gap, specimen size, design parameter of oval groove and steel grade changed. Results revealed that the cross sectional shapes predicted by the model were in good agreement with those obtained experimentally. We found that the analytic model not only has simplicity and accuracy for practical usage but also saves a large amount of computational time in comparison with finite element method.

• School Mathematics
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• v.17 no.4
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• pp.531-553
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• 2015

This study discussed a sketch map and planar figure, classical contents in math curriculum of Korea. Two problems were posed. One was the degree of difficulty and ambiguous intentions of some contents in 5th grade math textbook of 2009 revised curriculum. The other was the status of sketch maps and planar figures in more general view. We looked into elementary mathematics textbooks of former Korean national curriculums and other countries to discuss the problems. The reason why the present Korean textbook has such contents was considered, based on the result of searching former Korean and foreign textbooks. The suggestions in view of expression and building of 3D shapes were also talked.