• Steel and Composite Structures
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• v.42 no.5
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• pp.657-669
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• 2022

Structural materials can experience large plastic deformation under extreme cyclic loading that is caused by events like earthquakes. To evaluate the seismic safety of a structure, accurate numerical material models should be used. For a steel structure, the cyclic strain hardening behavior of structural steel should be correctly modeled. In this study, a combined hardening model, consisting of one isotropic hardening model and three nonlinear kinematic hardening models, was used. To determine the values of the combined hardening model parameters efficiently and accurately, the improved opposition-based particle swarm optimization (iOPSO) model was adopted. Low-cycle fatigue tests were conducted for three steel grades commonly used in Korea and their modeling parameters were determined using iOPSO, which was first developed in Korea. To avoid expensive and complex low cycle fatigue (LCF) tests for determining the combined hardening model parameter values for structural steel, empirical equations were proposed for each of the combined hardening model parameters based on the LCF test data of 21 steel grades collected from this study. In these equations, only the properties obtained from the monotonic tensile tests are required as input variables.

• Journal of the Korean Home Economics Association
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• v.17 no.3
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• pp.53-59
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• 1979

Vitamin contents of three grades of Korean laver high, medium and low were measured. They were cooked by different methods to examine changes in their vitamin content. Results of this experiment are as follows ; 1. Vitamin contained in loogr of laver amount to 13,200 I.U, for high grade, 16,100 for mediium grade, and 16,400 for low grade . The low -grade laver, which is interwoven with green laver, showed the highest vitamin content. 2. When laver was broiled sheet by sheet, its vitamin loss rate was 11% for high grade, 19% for medium grade, and 20% for low grade. Thus , the one with a higher vitamin content showed a higher vitamin loss rate. When two sheets of laver, which were put upon each other, were broiled, their vitamin loss rates were 2.3% for high grade, 1.73 % for medium grade, and 2.64% for low grade. Thus broiling laver at the unitof two to three sheets together is a way of decreasing the vitamin loss rate. 3. When laver was broiled with salt applied on its surface , its vitamin loss rate was 8.3% for high grade, 13% for medium grade, and 10.9% for low grade. When laver was broied at the unit of two sheets together after salt and sesame oil were added, its vitamin loss rate was 2.2% for high grade, 5.2% for medium grade, and 8.2% for low grade . The one with a higher vitamin content showed a higher vitamin loss rate. 4. When laver was mixed seasoned soysauce, its vitamin loss rate increased in process of time. In 48 hours after laver was mixed with seasoned soysauce , its vitamin loss rate read 24.2%, 27.1% and 35% respectively, for the three grades of laver. Thus the laver mixed with seasoned soysauce has to be used right after so cooked so as to obtained the highest possible vitamin content.

• Journal of Society of Preventive Korean Medicine
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• v.19 no.2
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• pp.123-133
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• 2015

The new formular for herbal medicine-safety classification in terms of evidence-based medicine was developed and applied to evaluate various herbal medicines in the previous study. This study is aimed to evaluate the frequently-used herbal medicines inducing toxic metabolites or reactive intermediates(RI), such as Ligusticum wallichii Franch, Angelica sinensis, Glycyrrhizae Radix, Rehmanniae Radix, based on 6 safety grades calculated from human equivalent dose(HED)-based MOS(margin of safety). HED-based MOS can be explained as the ratio of theoretical ALD(approximate lethal dose) of human as $LD_1$(lethal dose of 1%)/ clinical maximum dose as $ED_{99}$(Effective dose of 99%). The herbal medicine showing the ratio less than 1 belongs to Class 1, but the herbal medicine showing the ratio more than 500 belongs to Class 6 with the lowest toxicity. As a result, they were evaluated as class 2 for Angelica sinensis and Glycyrrhizae Radix, class 3 for Ligusticum wallichii Franch and Rehmanniae Radix. These resultant grades for 4 herbal medicines were lower than the grade expected under consideration that these herbal medicines are used very frequently in oriental clinics. These low grades would be due to their ingredients which is biotransformed to toxic metabolites.

• Journal of Korean Elementary Science Education
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• v.32 no.4
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• pp.495-502
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• 2013

The purpose of this study was to explore North Korean immigrant elementary students' cognitive and affective characteristics related to science education. A total of 68 North Korean immigrant students enrolled in 3 to 6 grades and 133 South Korean students in 4 and 6 grades in 3 South Korean elementary schools participated in the study. A short version of Group Assessment of Logical Thinking(GALT) was used to investigate the students' levels of logical thinking, and the Enjoyment of Science Lessons Scale(ESLS) of the Test of Science Related Attitudes(TOSRA) was administrated to examine their attitudes towards science lessons. The statistical analysis of data revealed that the level of logical thinking of the North Korean immigrant elementary students was very low and that this was also the case for the South Korean students. Especially, the mean score of logical thinking of the North Korean immigrant 6 graders was much lower when compared with that of the South Korean counterparts. For both the North Korean immigrant students and South Korean students, the enjoyment of science lessons decreased as they progressed through higher grades. This decreasing trend, however, turned out to be more serious in the South Korean elementary students. Based on these results, suggestions were presented to help successful science learning of North Korean immigrant elementary students.

• Fashion & Textile Research Journal
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• v.16 no.6
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• pp.935-944
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• 2014

This study was about to investigate the characteristics of elementary school students' feet growth, comparing and analyzed the measured values and the index values of 3D scan data. As the results from analyzing the measured values, the all measurement items excluding 'Toe 5 angle' showed some significant differences among the age classes, knowing that the elementary school students' feet were continually grown. Although, the items of length, thickness, width, height and circumference indicate some rapid growth of feet at 11 years old, but it appears slowing growth of 'Foot width' after the age of 11 years old. The angle item didn't show any sequential differences according to ages. As the results from analyzing the index values, the children in higher grades have longer 'Toe 5', thicker ankles, wider and thicker the superior part of feet than the children in lower grades. For the superior and the middle part of feet were lowly raised, their Arch height was low and thick. The inferior part of feet showed narrow width and higher height. Giving that the Medial ball width was wide and the Toe 1 angle is high for the children in higher grades, it is expected that the Metatarsophalangeal I might be more projected than that of children in lower grades. Likewise, knowing that the male students' feet shape was bigger than female students' feet from the result that the male students' index values were higher.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2008.05a
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• pp.1-46
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• 2008

The ability to control filler performance and fines retention is vital in the development of both filled and non filled grades, respectively. This is very important when achieving the desired sheet structure necessary to maximize machine performance and end user demands. A narrow balance exists in attaining the desired retention and formation particularly in systems with heavier ash loads and producing paper and paper board on higher speed high shear equipment. A new generation of both cationic and anionic micropolymer technologies has been developed. These water based chemistries are volatile organic compound (VOC) and alkyphenol ethoxylate (APE) free. When these novel micropolymers are applied with linear poly-acrylamide or in conjunction with inorganic microparticle technologies (such as silica or swellable minerals), substantial increases in drainage, fibre retention and ash retention are observed. These improvements have been observed not only in high filled wood and non wood containing grades such as fine paper and super calendared sheets (SCA), but also in low filled newsprint grades. Of particular note is the drainage improvement seen with the application of the cationic micropolymers in unbleached packaging grades with poly-acrylamide.

• The Journal of Engineering Geology
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• v.5 no.2
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• pp.167-179
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• 1995

The only three elements such as RQD, N -value and Es were used as a quantitative standard for the design of supporr pattern determidetion on subway line 8th in Seoul. Because the support pattern that was obtained by these elements could not he determined on the basis of the quantitative of geology and the orientations and properties of discontinuity planes, there have been some problems in determining the economic support pattern and tunnel stability. Therefore, in an attempt to determine the stable and economic support pattern with more quantitative elements, more flerrible rock mass classification with geologic conditions was performed by using RMR at 1745 sections and Q-system at 374 sections within Seongnam block on subway line 8th. Then, rusults by these two methods were compared with standard support pattern of the subway line 8th. Moreover, relationships between geology, geologic structures and topography to rock mass grades were studied. According to the rusult of this study, it is judged that the standard support pattern designed with PD-4 or PS - 4 should have been subdivided into 4~6 support patterns. Some sections where geologic structures such as faults and joints are developed tend to have rock mass grades. And they also have low rock mass grades near valley. On thr other hand, they show intermediate grades at piedmont area and the greatest ones at high mountains.

• Journal of Engineering Education Research
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• v.21 no.6
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• pp.63-73
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• 2018

This research aims to analyze core competencies of engineering students in Korea as well as to explore the application plans of extracurricular activities(hereafter, ECA) and programs in order to enhance their core competencies. Participation in ECA has long been recognized as having positive benefits and impacts upon students. To achieve the purpose of this study, first, we investigated whether there were differences between core competencies in undergraduates according to majors, gender and grades. 'Core competencies', first introduced in management theory as 'core competency' can be defined as personal attributes or underlining characteristics, capable of delivering a role or job. 'Core competencies' has received particular attention in recent years and there has been much related research (domestic and foreign) combined with diverse factors. However, few studies have addressed the question on engineering student's core competencies as well as the ways of their enhancement. This study was conducted with a total of 286 students, and core competencies have been measured online, through K-CESA. Our findings show that firstly, there were significant differences in undergraduate students' core competencies by majors. Engineering students scored significantly lower in core competencies overall. Second, there was no significant difference in students' core competencies by gender and grade. Third, there was a significant correlation among components of core competencies. Finally, there was a significant correlation between core competencies and grades(GPA, grades in major subject & liberal arts subject), rather levels in the correlation were low. Furthermore, the study suggested that the appropriate application of extracurricular activities would enhance core competencies of students.

• Journal of The Korean Association of Information Education
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• v.26 no.1
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• pp.1-10
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• 2022

With the development of artificial intelligence, society is moving toward another world that has never existed before. As a result, interest in artificial intelligence education is also increasing, and research on artificial intelligence education is being conducted more actively in Korea. However, many studies have been conducted focusing on the upper grades of elementary school, and curriculum and programs for the lower grades are still insufficient. Therefore, in this study, a total of 6 sessions of artificial intelligence programs were developed to understand image recognition for the lower grades of elementary school. The validity was secured by conducting expert validity for 8 experts, and the effectiveness was verified through the pre-post-response sample t-test by applying it to the experimental group. As a result, both artificial intelligence understanding and artificial intelligence attitude showed statistically significant results, and both the interest and difficulty of educational programs were found to be suitable for lower grade students. Based on the contents of this study, it is necessary to review its application and effectiveness in various environments through follow-up studies in the future.

• 한국정보교육학회:학술대회논문집
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• 2021.08a
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• pp.269-274
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• 2021

With the development of artificial intelligence, society is moving to a different world. As a result, amid growing interest in artificial intelligence education, research on how to teach artificial intelligence is also being conducted more actively in Korea. However, a lot of research is being conducted around the upper grades of elementary school, and curriculum and programs for the lower grades are insufficient. Therefore, this study developed an artificial intelligence program for lower grades. Among them, it was developed focusing on artificial intelligence image recognition. It compares image recognition methods of people, animals, and computers, identifies the characteristics of fallen leaves, and helps them understand the image recognition process of artificial intelligence by classifying them according to the characteristics of fallen leaves. I hope this program will help elementary school students understand the image recognition principle of artificial intelligence in the future.