• Journal of the Institute of Convergence Signal Processing
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• v.9 no.1
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• pp.10-17
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• 2008

The purpose of this thesis is to reduce of error for source location through acoustic emission(AE) signal, generated elastic wave from crack growth to leak for facility diagnosis. Especially, in order to overcome noise from original signal, this paper proposed enhancement of source location by using noise reduction based on wavelet transform. To evaluate actual performance in experiments, Pencil Lead Break is used crack signal source on the aluminum plate and drain valve of air compressor is used as substitute pressure vessel to generate leak signal. In signal processing, wavelet shrinkage and soft threshold are used to discriminate signal source and then source location techniques have been effectively used with group velocity using material property and time difference between sensor using cross correlation. Source location for crack and leak test have some difference, but the result show that improved 30% with a average length within 10.46mm in crack test and improved 2% compare with average filter in leak test when we applied wavelet transform.

• Journal of the Korean Society for Computer Game
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• v.31 no.4
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• pp.1-8
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• 2018

The present study investigated the validity of a serious game named 'Draw Ttoring' developed for accessment of children's attention and tried to provide the basic information about it. To this goal, we tested it to 284 elementary school students in measuring various behavior data(reaction time, total playing time, correct rate, discrepancy between type of TMT). Futhermore, the behavior data was compared with academic achievement to see the external validity. In results, 'Draw Ttoring' showed various behavior data and correlation with academic achievement. In Type A of TMT, total time and reaction time had a correlation with academic achievement, while, in Type B of TMT, total time and correct rate did. Mental flexibility calculated by the discrepancy between Type A and Type B showed also the positive correlation with academic achievement. These results showed that the serious game named 'Draw Ttoring' can provide more various information about children attention and these can't be observed by traditional paper pencil test. Finally, serious game can provide an good alternative method to access children's cognition.

• The Journal of Korean Association of Computer Education
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• v.17 no.2
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• pp.39-51
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• 2014

In high-stakes tests for large groups, the efficiency with which students' responses are distributed to raters and how systematic scoring procedures are managed is important to the overall success of the testing program. In the scoring of constructed response items, it is important to understand whether the raters themselves are making consistent judgments on the responses, and whether these judgments are similar across all raters in order to establish measures of rater reliability. The purpose of this study was to design, develop and carry out a pilot test of an online scoring system for constructed response items administered in a paper-and-pencil test to large groups, and to verify the system's reliability. In this study, we show that this online system provided information on the scoring process of individual raters, including intra-rater and inter-rater consistency, compared to conventional scoring methods. We found this system to be especially effective for obtaining reliable and valid scores for constructed response items.

• Journal of The Korean Association For Science Education
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• v.17 no.1
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• pp.65-73
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• 1997

The purpose of this study is to develop a valid and reliable instrument, applicable to high school Earth Science class experiment. In advance of developing items, I was selected 14 inquiry process skills and specified evaluative objectives for each of them to develop scales and criteria for them. I developed 28 evaluation items for 5 experiment subjects among those of high school Earth Science class. The first field trial was performed a sample of 5 high school students, and the second one using a sample of 25 high school students. The results are as follows. (1) The content validity and reliability(Cronbach $\alpha$) of the developed items were 82.7% and .86, respectively, the developed instrument in this study is considered valid and reliable. (2) The average difficulty index was .69 and the discrimination index was .30. (3) Answer sheets based on the reported results were rated 5 teachers and Inter-rater Reliabilitiy and Inter-rater Consistency were analyzed, its indices were .80 and .76, respectively. (4) The developed items show a low coefficient of .45 with TESIS, a set of paper-and-pencil test items developed by Lee, Hang-Ro(1991). That the experiment assessment is solely subject to the rater's viewpoint has been one of the major problems raised concerning the matter. This research, however, shows that a set of more specified scales and criteria for the evaluation will make it more valid, reliable and efficient.

• Journal of the Korean Society of School Health
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• v.29 no.3
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• pp.123-131
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• 2016

Purpose: Human Papillomavirus(HPV) vaccination is the best prevention for cervical cancer. Therefore, this study was to examine the best predictors of HPV vaccination status in female nursing university students. Methods: Five hundred and forty junior and senior female nursing students from Seoul and provinces of Kyunggi, Chungcheong and Gyungsang completed paper and pencil questionnaires. Descriptive statistics, $x^2$ test, t-test, and multiple logistic regression with dummy variables were conducted using SAS 9.2. Results: Of the total students, 56.8% were vaccinated. As a result of the analysis of the bivariate relationships, family economic status, school type, perceived susceptibility, perceived benefit and perceived barriers (cost, time, distance from hospital and side effects) were significantly related to vaccination status. After controlling for the general characteristics and the HPV related knowledge score, higher family economic status (Adjusted Odds Ratio [AOR]: 3.78, 95% Confidence Interval [CI]: 1.21~11.76), private university (AOR: 1.69, 95% CI: 1.14~2.53), higher perceived benefit (AOR: 1.80, 95% CI: 1.47~2.20), lower perceived barrier (cost) (AOR: 0.86, 95% CI: 0.74~0.99), lower perceived barrier (time) (AOR: 0.71, 95% CI: 0.61~0.84), and lower perceived barrier (side effects) (AOR: 0.82, 95% CI: 0.72~0.94) were significantly related to HPV vaccination. Perceived benefit, perceived barrier (time) and perceived barrier (side effects) were the top 3 predictors of HPV vaccination status. Conclusion: This study suggests that vaccinated female nursing students were more likely to be from higher family economic status and private universities and have a higher perception of benefit and a lower perception of barriers (cost, time, and side effects). Thus, efforts to increase HPV vaccination rates of female nursing students should focus on improving their perception of benefit while lowering their perception of barriers, particularly cost, time and side effects.

• Journal of Korean Elementary Science Education
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• v.24 no.2
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• pp.130-137
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• 2005

Elementary preservice teachers' understanding about the insect molt and metamorphosis was examined. Data were collected through the paper-pencil test of 448 junior students at a National University of Education. The instrument used was developed by Son(2003) and modified for the test. The results are as follows: First, Only 3.1$\%$ of students had a scientific concept on the molt periods in the insect life cycle. Students had an alternative conception that molt occurs either only in the larval period (29.9$\%$) or only in the period from pupa to adult (22.3$\%$). The percentage of the students thinking that molt occurs in the period from larva to pupa was low. Second, 98$\%$ of students stated that molt has to do with the larval growth, but 39.1$\%$ of students had an alternative conception that molt occurs after the larval growth at each instar. 25.1$\%$ had a conception that molt is related with the larval growth, but did not show any further understanding. Third, most students understood the correct meaning of metamorphosis. 34..2$\%$ of students had an alternative conception that metamorphosis occurs only in the period changing from pupa to adult, and only a few thought that it occurs in the period from larva to pupa. 24.8$\%$ of students had a scientific concept on the periods in which metamorphosis occurs. Fourth, some students understood the hatching process as molt in the sense that the egg shell is taken off (21.0$\%$), and as metamorphosis in terms of the appearance change from egg to larva (25.0$\%$). Fifth, 35.5$\%$ of students selected bees as an insect of incomplete metamorphosis, and 35.3$\%$ responded 'I have no idea', showing that they had poor understanding about the insect life cycle.

• Archives of design research
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• v.12 no.4
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• pp.211-220
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• 1999

This study purposed more effective drawing process in practical lecture with students. Researched materials were constitution to a semester of presentation technique curriculum major in industrial design for freshman course. Students exert to entrance examination of university to get a good point in practical test. There did not have creative action in minds. But, design required concept of good idea sketch and creative technique. At study process should make correction a reform to sketch skill by repeat practicing with misunderstand drawing or imitative idea sketch. According to the practical test result & response revised lecture schedule. And then, I had survey to questionnaire paper for feedback by trial result. Besides, I was study to effect use the drawing materials for example, colored pencil, marker pastel. I think important to first use to way understanding materials and basic training. Design education be driven to new creative sketch skill. Design is the creative process to which brings ideas to reality.

• Journal of Elementary Mathematics Education in Korea
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• v.6 no.1
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• pp.23-40
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• 2002

Historically, the use of algorithms has been emphasized in the mathematics curriculum at the elementary school mathematics. The current reform movement in our country are seemed to emphasize the importance of algorithms in favor of problem-solving approaches, the conceptualization of mathematical processes and applications of mathematics in real world situations. Recently, children may come to school with a fairly well-developed attitude about mathematics and mathematical ideas. That is, they do not come to school and to learning mathematics with a clean slate. Because they have already formed some partial mathematical concepts in a wide variety of contexts. Many kindergarten children have attended pre-school programs where they played with blocks, made patterns, and started adding and subtracting. It seems that there are psychological change attitudes of the children in upper grades toward learning mathematics. In our elementary school mathematics, almost every student are still math anxious or have developed math anxiety because of paper-pencil test. In these views, this paper is devoted to introduce and apply to second grade students in ND-elementary school in Taegu City the new method for learning addition and subtraction so called ‘Mrs Weill's Hill’, which is believed as a suitable method for children with mathematical teaming disabilities and Math anxiety.

• Smart Structures and Systems
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• v.12 no.2
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• pp.97-119
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• 2013

This paper presents numerical and experimental results on the use of guided waves for structural health monitoring (SHM) of crack growth during a fatigue test in a thick steel plate used for civil engineering application. Numerical simulation, analytical modeling, and experimental tests are used to prove that piezoelectric wafer active sensor (PWAS) can perform active SHM using guided wave pitch-catch method and passive SHM using acoustic emission (AE). AE simulation was performed with the multi-physic FEM (MP-FEM) approach. The MP-FEM approach permits that the output variables to be expressed directly in electric terms while the two-ways electromechanical conversion is done internally in the MP-FEM formulation. The AE event was simulated as a pulse of defined duration and amplitude. The electrical signal measured at a PWAS receiver was simulated. Experimental tests were performed with PWAS transducers acting as passive receivers of AE signals. An AE source was simulated using 0.5-mm pencil lead breaks. The PWAS transducers were able to pick up AE signal with good strength. Subsequently, PWAS transducers and traditional AE transducer were applied to a 12.7-mm CT specimen subjected to accelerated fatigue testing. Active sensing in pitch catch mode on the CT specimen was applied between the PWAS transducers pairs. Damage indexes were calculated and correlated with actual crack growth. The paper finishes with conclusions and suggestions for further work.

• Tunnel and Underground Space
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• v.21 no.5
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• pp.349-358
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• 2011

This paper introduces a new P wave arrival time determination algorithm of acoustic emission (AE) suitable to identify P waves with low signal-to-noise ratio generated in rock masses around the high-level radioactive waste disposal repositories. The algorithms adopted for this paper were amplitude threshold picker, Akaike Information Criterion (AIC), two step AIC, and Hinkley criterion. The elastic waves were generated by Pencil Lead Break test on a granite sample, then mixed with white noise to make it difficult to distinguish P wave artificially. The results obtained from amplitude threshold picker, AIC, and Hinkley criterion produced relatively large error due to the low signal-to-noise ratio. On the other hand, two step AIC algorithm provided the correct results regardless of white noise so that the accuracy of source localization was more improved and could be satisfied with the error range.