• Journal of Applied Reliability
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• v.14 no.4
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• pp.230-235
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• 2014

The failure modes of pneumatic directional control valves include leakage, wear of the spool seal, and sticking of the spool. Among them, the main failure mode of the valve is leakage. The leakage is caused by the wear of the spool seal. However, due to the characteristics of the seal material, the leakage rate is fluctuated a lot rather than constantly increased over time. If life analysis is performed using the first time data of leakage failure, predicted life cycles can be different from the real life cycles. This paper predicts life cycles of the pilot pneumatic directional control valve based on the three point moving average which considers the average of the fluctuating leakage rate.

• Journal of Elementary Mathematics Education in Korea
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• v.15 no.1
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• pp.121-139
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• 2011

This study conducted experimental problem posing activities using real-life materials. This study investigated the changes on students' mathematical thoughts and attitudes through the activities. This study is conducted via participation of students in a 5th grade class of N elementary school located in Daegu city. As a qualitative case study, this study focused on processes of problem posing rather than results. The problems applying new situations appear, and the used mathematical terms, units, and figures became more practical. The numbers of problems made are increased gradually, and more complex conditions are added as activities are performed. Most of the students revealed interests about problem making activities.

• Journal of Applied Reliability
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• v.15 no.3
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• pp.139-144
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• 2015

Track drive unit adopted in the small sized excavator generally have been used in the construction equipment under the 10 tons as the driving device with forwarding and reversing of excavator. It is required to study the accelerated life test applied by over torque and speed to test the durability life test reflected the many driving modes of small sized excavator and also need to equip the comprehensive performance and life test equipments to do the various performance tests. This study had analyzed the failure modes of the components, and calculated the equivalent loads investigated the used loads in the real field conditions and elicits the acceleration factor adopted in the inverse power model. Also, this study have considered the changes of the acceleration factor and the durability test time in the case of the rotary group and the bearing through analyzing the main failure modes. It was calculated the no failure test time about 2 samples and confidence level 90% and elicited the accelerated life time 720 hours.

• Journal of Korean Home Economics Education Association
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• v.15 no.1
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• pp.57-68
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• 2003

The purpose of this study was to research high school students’ practical awareness about the contents(classify them into four units. choice and dressing of clothes. textile and management of clothes. design and sewing of clothes. knitting and embroidery) clothing and textiles education in their real life. This is the investigation of which 576 high school students located in Choongchungnam$.$bukdo. Junrabukdo, Daeseon. In this statistical analysis. SPSS 10.0 for Windows Program was utilized to calculate percentage. mean and standard deviation. Also. these materials were verified by t-test. One-way Anova . Pearson’s correlation coefficient. The main results of obtained this study are as follows High school students’ practical awareness about the contents of clothing and textiles education in their real life appears to be low(only 9 items were over median point of 3.0). There was a significant difference in Practical awareness of contents of clothing and textiles education according to demographic variables. and correlation of variables differed significantly. These results should be provide fundamental information for improving students’ practical practice in their real life Since this study has touched only limited research on the topic of clothing and textiles education. it is essential that further research covering a wider array of themes be done in the future.

• Korean Journal of Human Ecology
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• v.6 no.2
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• pp.83-95
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• 2003

The purpose of this study was to research adolescents' practical awareness about the contents(classify them into four units, choice and dressing of clothes, textile and management of clothes, design and sewing of clothes, knitting and embroidery) clothing and textiles education in their real life. This is the investigation of which 730(middle school students 246, high school students 248, university students 236) girl students located in Junrabukdo and Choongchungnam. In this statistical analysis. SPSS 10.0 for Windows Program was utilized to calculate percentage, mean and standard deviation. Also, these materials wert verified by t-test, One-way Anova. The main results of obtained this study are as follows. Adolescents' practical awareness about the contents of clothing and textiles education in their real life appears to be low(only 8 items were over median point of 3.0) There was a significant difference in practical awareness of contents of clothing and textiles education according to early$.$middle$.$latter adolescents and demographic variables differed significantly. These results should be provide fundamental information for improving students' critical practice in their real life. Since this study has touched only limited research on the topic of clothing and textiles education, it is essential that further research covering a wider array of themes be done in the future.

• Communications of Mathematical Education
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• v.32 no.3
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• pp.341-362
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• 2018

The purpose of this study is to develop a STEAM education model on the basis of mathematics curriculum using real life context, and to analyze the effect of the class based on developed model to make applicable pedagogical discussion. For this purpose, STEAM class materials that can be used in terms of recognition, connection, extension, and application of mathematical concepts, principles and laws are considered, taking into consideration the ways in which real life contexts and mathematical learning could be harmonized. As a results of using these materials, it was empirically confirmed that students' cognitive thinking and affective aspects abilities were improved. The STEAM instruction centered on the mathematics curriculum and the mathematics class based on the data developed in this study have a unique identity compared to the conventional general mathematics teaching methods using the textbooks. And it is pursuing the future class model which could present desirable creativity and personality education. The result of this study would provide preliminary data and meaningful implications to the researchers for next curriculum and concomitant instructional materials as well as the mathematics teachers.

• Journal of The Korean Association For Science Education
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• v.25 no.7
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• pp.754-764
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• 2005

The purpose of this study was to develop experimental modules that would enhance science the process skills of secondary school students. The modules were composed of real-life materials on the subjects of light, movement, force, water, and heat. Each module consisted of four to six activities, and provided student worksheets and teacher guides. Physics teachers were invited to a workshop specially held to identify whether these modules would befit the improvement of student science process skills. A majority of the teachers believed the modules to be valuable instructional materials which might enhance student science process skills in the Korean secondary school science classes.

• Agricultural and Biosystems Engineering
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• v.1 no.1
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• pp.16-21
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• 2000

Measurement of spray deposit is necessary for evaluation of a chemical application technology. However it is not easy and time consuming. A simple method for measuring the deposition amount of spray using a tracer and a spectrophotometer was developed. Various materials were tested to determine an adequate tracer. Food dye was selected as a tracer, because it was cheep and easily treatable. Using NIRS(Near Infrared Reflection Spectrophotometer), a regression curves between maximum absorbance of a solution and concentration of the tracer were obtained. Yellow food dye solution showed a peak of spectrum at 452 nm, and absorbance of peak showed a tendency to increase as concentration increased. Green or pink food dye were tested and judged to be good tracers. However, tracer concentration should not exceed certain limits in order to measure maximum absorption. Using spraying liquid with known tracer concentration and known amount of washing liquid, spray deposit amount on real targets on leaves could be estimated at less than 13% error level.

• Advances in environmental research
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• v.3 no.4
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• pp.367-377
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• 2014

In this study, we investigated a life cycle assessment (LCA) of six roof-waterproofing systems [asphalt (C1), synthetic polymer-based sheet (C2), improved asphalt (C3), liquid applied membrane (C4), Metal sheet with asphalt sheet (N1), and liquid applied membrane with asphalt sheet (N2)]for reinforced concrete building using an architectural model. To acquire accurate and realistic LCA results, minimum units of material compositions for life cycle inventory and real data for compositions of waterproofing materials were used. Considering only materials and energy demands for waterproofing systems per square meter, higher greenhouse gas (GHG) emissions could be generated in the order of C1 > N2 > C4 > N1 > C2 > C3 during construction phase. However, the order was changed to C1 > C4 > C3 > N2 > N1 > C2, when the actual architecture model was applied to the roof based on each specifications. When an entire life cycle including construction, maintenance, and deconstruction were considered, the amount of GHG emission was in the order of C4 > C1 > C3 > N2 > C2 > N1. Consequently, N1 was the most environmental-friendly waterproofing system producing the lowest GHG emission. GHG emissions from maintenance phase accounted for 71.4%~78.3% among whole life cycle.

• Food Science and Biotechnology
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• v.18 no.5
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• pp.1118-1123
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• 2009

Event-specific real-time polymerase chain reaction (PCR) detection method for genetically modified (GM) maize MIR604 was developed based on integration junction sequences between the host plant genome and the integrated transgene. In this study, 2 primer pairs and probes were designed for specific amplification of 100 and 111 bp DNA fragments from the zSSIIb gene (the maize endogenous reference gene) and MIR604. The quantitative method was validated using 3 certified reference materials (CRMs) with levels of 0.1, 1, and 10% MIR604. The method was also assayed with 14 different plants and other GM maize. No amplification signal was observed in real-time PCR assays with any of the species tested other than MIR604 maize. As a result, the bias from the true value and the relative deviation for MIR604 was within the range from 0 to 9%. Precision, expressed as relative standard deviation (RSD), varied from 2.7 to 10% for MIR604. Limits of detections (LODs) of qualitative and quantitative methods were all 0.1%. These results indicated that the event-specific quantitative PCR detection system for MIR604 is accurate and useful.