• Journal of The Korean Association For Science Education
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• v.21 no.4
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• pp.738-744
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• 2001

This study investigated the influences of an instructional method related to problem solving. The new instruction consists of a four-stage problem-solving strategy emphasizing 'planning' and 'checking' stages, and a think-aloud paired problem solving in order to check students' performances in solving problems. Two high school classes (n=91) were randomly assigned to the treatment and the control groups. Prior to the instructions. students' perception of involvement and self-efficacy were examined, and their scores were used as covariates in the analysis. Students' problem-solving ability, perception of involvement. and self-efficacy were examined after the instructions. The test scores of the treatment group were significantly higher than those of the control group in the problem-solving ability and the perception of involvement. However, there was no significant difference between the scores of the two groups in the self-efficacy.

• Journal of The Korean Association For Science Education
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• v.16 no.4
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• pp.429-440
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• 1996

This study examined the effects of the ARCS model for science education and found a way of improving ARCS while finding any weaknesses. More specific research questions were as follows: 1) Does the ARCS model enhance the learners' achivement in highschool Earth Science significantly?; 2) Does the ARCS model enhance the learners' motivation in highschool Earth Science significantly?; 3) What are the weaknesses of the prescriptions of the ARCS model for designing a lesson, if any?; 4) How can the weaknesses of the prescriptions of the ARCS modeI be overcome? In order to fulfill the purpose of this study, the two major research methodologies were implemented: pretest-posttest control group design and formarive research. This study was conducted in two distinct phases: 1) designing a set of instructions for 4 weeks with the principles of the ARCS model (to find the weaknesses of the ARCS model) and 2) teaching the instructions and checking the effectiveness of the ARCS model by pretest and posttest with control and experimental groups(to find weaknesses of the underlying theory of the ARCS). After the experiment, each group took an achievement test and an attitude test on the given instruction and gathered data were analyzed with t-tests. Also, from each four classes 7$\sim$8 students were randomly sampled and individually interviewed about the instructional effectiveness and their preference on the instructions. The results of this study are summarized as follows: Significant differences between the control group and experimental group are seen in three components; Attention, relevance, and satisfaction. No significant differences are seen in the attitude of confidence. The weakness of the prescriptions of the ARCS model, are insufficient of strategy for 'confidence'. For overcoming the weaknesses of the prescriptions of the ARCS model, developmental type research is needed.

• The Journal of the Acoustical Society of Korea
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• v.32 no.3
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• pp.269-278
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• 2013

The speech recording of the National Archives of Korea contains very important traces which represent modern times of Korea. But the way to be recorded by analogue is easily contaminated as time goes by. So it has to be digitalized for management and services. Consequently, restoration method of distorted speech is needed. We propose the four classes for each distortion kind and apply restoration algorithms for the cases of speech level, stationary noise and abrupt noise. As a result, speech volume adjusts to -26 dBov for only on the speech region and SNR improves above 10dB. Especially, conventional way to remove the noise is almost impossible because we need to listen to all of them but it can be more effective by adaptation of auto restoration algorithm.

• Structural Engineering and Mechanics
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• v.42 no.4
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• pp.507-530
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• 2012

Age-related problems especially corrosion and fatigue are normally suffered by weatherworn ships and aging offshore structures. The effect of corrosion is one of the important factors in the Common Structural Rule (CSR) guideline of the ship design based on a 20 or 25 years design life. The aim of this research is the clarification of the corrosion effect on ultimate strength of stiffened panels on various types of double hull oil tankers. In the case of ships, corrosion is a phenomenon caused by the ambient environment and it has different characteristics depending on the parts involved. Extensive research considering these characteristic have already done by previous researchers. Based on this data, the ultimate strength behavior of stiffened panels for four double hull oil tankers such as VLCC, Suezmax, Aframax, and Panamax classes are compared and analyzed. By considering hogging and sagging bending moments, the stiffened panels of the deck, inner bottom and outer bottom located far away from neutral axis of ship are assessed. The results of this paper will be useful in evaluating the ultimate strength of an oil tanker subjected to corrosion. These results will be an informative example to check the effect of ultimate strength of a stiffened panel according to corrosion addition from CSR for a given type of ship.

• Korean Journal of Food Science and Technology
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• v.38 no.2
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• pp.262-267
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• 2006

Inhibitory effects of fungal metabolites isolated from foodstuffs on growth of human cancer cell lines were evaluated. Isolated strains were divided into four classes based on color (aerial, reverse), shape, and growth speed. Fungal metabolites extracted with ethyl acetate were investigated for their growth inhibition on six kinds of human cancer cells by MTT assay. Ethyl acetate extract showed high growth inhibition against all cancer cells tested, with D4 exhibiting the strongest growth inhibition effects against Kato III, AGS, Hepa1c1c7, and MDA-MB-231 cancer cells. These results suggest ethyl acetate extract from fungal metabolites as effective natural cancer therapeutic material.

• Korean Journal of Food Science and Technology
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• v.14 no.4
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• pp.382-387
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• 1982

Lipids and fatty acid composition of free and bound lipids isolated from four barley varieties were studied. The average content of purified free and bound lipids were 1.57% and 0.48%, respectively. The average contents of neutral lipids, glycolipids and phospholipids in the free and bound lipids contain 81.1% and 16.4%, 11.4%, and 6.8%, 6.7% and 75.5%, respectively. Among the neutral lipids in both free and bound lipids, triglycerides were the predominant with free fatty acids, monoglycerides, diglycerides, free sterol esters being present as minor components. Linoleic, oleic, palmitic and linolenic acid were the principal fatty acids in both free and bound lipids. And fatty acid composition of lipid classes in free and bound lipids were determined.

• Journal of the Korea society of information convergence
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• v.8 no.1
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• pp.39-47
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• 2015

This study was conducted to identify the experience that applied Flip Learning to preparatory childhood teachers. The target of study is 76 students who were in the first semester of the first year of three-year early childhood education major and took teaching profession subjects for 2 credits. The semester was run for 13 week-course from the beginning of March to the middle of June. Flip Learning was applied to all the classes. Data was collected through qualitative analysis of participants' journals and was concluded with the category of three strengths and four weaknesses. The strengths were firstly active class participation, secondly repetition learning, and thirdly self directed learning. The weaknesses were firstly a burden on class time, secondly improvement on Flip Learning methods, and thirdly a need of ability for self-directed learning and fourthly the experience of environmental unstability for prior learning. It suggests application examples of more effective teaching and learning methods for college professors and students through the case that applied Flip Learning to preparatory early childhood teachers.

• Journal of Korean Elementary Science Education
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• v.39 no.1
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• pp.117-132
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• 2020

The purpose of this study is to investigate elementary school teachers' awareness of Artificial Intelligence (AI) and find out how to apply it in elementary science education. The survey was conducted online and involved 95 teachers working in the metropolitan area. The results of this study are as follows. First, teachers need to learn about the general characteristics of AI and how to apply it to education. Second, science classes had the highest preference for AI among elementary school subjects. Third, the preference for AI application by elementary science field was 68.4% for earth and space, 54.7% for exercise and energy, 32.6% for matter, 27.4% for life. Fourth, AI-based Science Education (AISE) teaching- learning strategies were developed based on AI characteristics and the changing perspective of elementary science education, AISE's teaching-learning strategies are five: 'automation', 'individualization', 'diversification', 'cooperation' and 'creativity' and teachers can use them in teaching design, class practice and evaluation stages. Finally, the creative problem-solving Doing Thinking Making Sharing (DTMS) model was devised to implement the creativity strategy in AISE. This model consists of four-steps teaching courses: Doing, Thinking, Making and Sharing based on the empirical learning theory. In the future, follow-up research is needed to verify the effectiveness of this model by applying it to elementary science education.

• Human Ecology Research
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• v.58 no.4
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• pp.483-496
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• 2020

This study examined the effects of eating alone, meal type, and dietary lifestyles on healthy eating capability of one-person households. We analyzed the mediation effects of weekly frequencies of each meal type taken by one-person households between eating habits such as eating alone and dietary lifestyles of one-person households and healthy eating capability. We also analyzed data from the 2019 Food Consumption Behavior Survey using a sample of 688 one-person households. Factor analysis, latent profile analysis, structural equation model analysis was conducted; direct and indirect effects of independent variables were tested using bootstrap method. The major results were as follows. Frequency of eating alone was about 10 times a week on average; one-person households had home-made meals about 12 times a week, for restaurant meals, 4 times, for delivered/take-out food, 0.39 times, and for other types, 0.44 times. Weekly frequencies of eating alone and meal types taken by one-person households were significantly different among the different socio-demographic groups. Dietary lifestyle was classified into four classes: traditional, health ignorant, food lifestyle ignorant, and balanced. Eating alone and dietary lifestyle had a significant effect on weekly frequency of each meal type. Frequencies of eating alone, balanced dietary lifestyle, and taking home-made meals had a positive direct effect on healthy eating capability, and frequency of taking delivered or take-out food and food consumption ignorant lifestyle had a negative direct effect. Eating alone, balanced and traditional dietary lifestyles had a positive indirect effect through the meal type; however, watching Mug-bang had a negative indirect effect.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.10
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• pp.56-61
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• 2008

Because the harmonic disturbance characteristic which makes voltage drop and the deterioration of instantaneous power quality in electrical power system overheats the NGR and the customer capacitor and malfunctions the OCGR and AMR, it is necessary for electric power company to take active measures to reduce this disturbance. International Electrotechnical Commission(IEC) 61000-3-2 specifies limits for harmonic current emissions generated by low voltage(LV) electrical equipment whose input current $\leq$ 16(A) per phase. Analysis shows that limits for Class A equipment in IEC are calculated using the reference impedance of LV system and maximum permissible voltage and limits for other Classes are also calculated based on limits for Class A. Therefore we have calculated four(4) internal limits for LV electrical equipment using the korea reference impedance and maximum permissible voltage in this paper.