• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.11 no.6
• /
• pp.75-81
• /
• 2012

Dissimilar material friction welding such as STD11 and SCM440, we are considering of such things as strength and tenacity of welding interface, which consist of friction welding rotation frequency, friction heating pressure, upset forging-pressure, friction heating time, and upset forging-pressure time. From the study, obtaining the interrelationship between welding condition and quality(toughness, tenacity), we can set the best range of welding condition. while performing acoustic emission examination for the nondestructive evaluation, we can deduce the interrelationship among total acoustic emission counts, friction welding variable, and quality during friction welding, which can solve the manufacturing difficulty and enhance the economic value.

• Computers and Concrete
• /
• v.17 no.6
• /
• pp.831-848
• /
• 2016

This study aims to characterize the multiple cracking behavior of HTPP-ECC (High tenacity polypropylene fiber reinforced engineered cementitious composites) by Digital Image Correlation (DIC) Method. Digital images have been captured from a dogbone shaped HTPP-ECC specimen exhibiting 3.1% tensile ductility under loading. Images analyzed by VIC-2D software and ${\varepsilon}_{xx}$ strain maps have been obtained. Crack widths were computed from the ${\varepsilon}_{xx}$ strain maps and crack width distributions were determined throughout the specimen. The strain values from real LVDTs were also compared with virtual LVDTs digitally attached on digital images. Results confirmed that it is possible to accurately monitor the initiation and propagation of any single crack or multiple cracks by DIC at the whole interval of testing. Although the analysis require some post-processing operations, DIC based crack analysis methodology can be used as a promising and versatile tool for quality control of HTPP-ECC and other strain hardening composites.

• International Journal of Advanced Culture Technology
• /
• v.11 no.4
• /
• pp.286-294
• /
• 2023

We studied learners' perceptions and learning styles of project research activities in the chemical field conducted by 54 science high school students. In a survey of students' perceptions of task research, positive responses were found in "internal motivation," "cooperation," "task solving," and "tenacity and immersion," and statistically significant differences were found in "self-directedness," "cooperation," and "tenacity and immersion" by year. The 'lower' group responded most positively in the 'cooperation' category, and the 'higher' group responded most positively in the 'task solving' category. As a result of investigating the learning styles of the students who conducted the task research, it was found in the order of assimilator, converger, accommodator, and diverger. The assimilators showed the characteristic of systematically and scientifically approaching the problem. Convergers were found to have excellent problem-solving and decision-making ability, are practical, and have experimental-based thinking characteristics. In this study, the characteristics of science high school students showed well in the results of the learning style performed.

• 한국도로학회:학술대회논문집
• /
• 2002.10a
• /
• pp.61-66
• /
• 2002

• Korean Journal of Human Ecology
• /
• v.22 no.1
• /
• pp.131-140
• /
• 2013

Eco-friendly and health-functional clothing is now becoming the target of the worldwide hot trends. The purpose of this study is to develop an eco-friendly textiles to decrease environmental pollution and to be harmless for human health by investigating how the natural chorangak liquid treatment affects the changes of mechanical properties and the hand of silk fabrics according to different treatment conditions. Treatment was varied with various temperatures ($85^{\circ}C$, $90^{\circ}C$, $95^{\circ}C$) for 90 seconds after degumming. The results were as follows: 1) The natural chorangak liquid is the most effective at the ratio of glacial acid 200ml with eggshell 20g minimizing the time limit and sludge reduction. Its treatment of silk fabrics is optimized at $90^{\circ}C$ for 90 seconds with 25% conc. after degumming when considering tenacity and elongation. 2) After the treatment, tenacity and elongation of specimen are increased compared with those of degummed silk fabrics. 3) After analyzing the effect of the treatment on the characteristic values of basic mechanical properties of silk fabrics, mechanical properties (tensile, bending, shearing, compression, surface) are overall improved. The properties of thickness and weight are increased as well. 4) Based on the clear analysis on effects of the treatment on the mechanical properties and the hand of silk fabrics, the level of THV was enhanced from good to excellent. Therefore, chorangak liquid can be utilized satisfactorily as a new finishing agent for developing eco-friendly textiles.

• Korean Journal of Food Science and Technology
• /
• v.31 no.4
• /
• pp.977-983
• /
• 1999

This study was conducted to investigate the effects of emulsifiers on the quality of steamed bread. initial pasting temperature of the flour was decreased from $63.8^{\circ}C$ to $59.40{\sim}62.95^{\circ}C$ by adding 1% of emulsifiers such as monoglyceride, lecithin, sugar ester and diacetyl tartaric acid esters of mono- and diglycerides (DATEM). But other rheological properties of the doughs were varied with different emulsifiers. Flour with 1% sugar ester showed the lowest value of final viscosity and set back, therefore sugar ester might be effective for retard the retrogradation of bread. By alveogram test, flour with 1% DATEM showed the highest value of P (tenacity) but the lowest value of L (extensibility), that means DATEM might be effective for strengthening tenacity of dough but it lowered extensibility. After 72 hours of storage test, the steamed bread based on the flour with 1% monoglyceride showed the best crumb softness and the highest score of sensory test.

• Science of Emotion and Sensibility
• /
• v.17 no.3
• /
• pp.75-82
• /
• 2014

This study investigated the physical properties of aramid/nylon ATY and aramid ATY for protective garments according to the aramid and nylon characteristics fed on the core and effect components of air jet texturing equipment. Tenacity decrease of aramid ATY was much more higher than that of nylon ATY because of slick of aramid filament surface. Tenacity of aramid/nylon ATY was most affected by the tenacity of nylon on the effect component of ATY. Breaking strain of nylon ATY was two times higher than that of nylon before air jet texturing, then, in case of aramid ATY and aramid/nylon ATY, were 5.9-6.7 times higher than those before air jet texturing. Initial modulus decrease of aramid ATY showed 86.5% of initial modulus of aramid before air jet texturing, then aramid/nylon hibrid ATY showed arithmetic average value of initial modulus of aramid and nylon ATY. Wet and dry thermal shrinkages of aramid/nylon hybrid ATY were dominated by those of nylon filament on the effect component of ATY.

• Textile Coloration and Finishing
• /
• v.25 no.3
• /
• pp.223-231
• /
• 2013

This research has a main focus on providing fundamental data for on-the-spot industrial fields by comparing and contrasting physical properties of fluffy spun-like material. The fluffy spun-like yarn is developed as fluffy yarn similar to natural spun-like yarn by treating polyester(FDY and + type shaped DTY) with ATY machine. In this experiment, using ATY machine for raw material texturing, we produced two fluffy yarns: (i) + type shaped(50d/36f, DTY) as core yarn and 100d/192f FDY as effect yarn[ATY(D)], (ii) FDY(75/36) as core yarn and 100d/192f FDY [ATY(F)] as effect yarn. After producing thous yarns, we twisted them with 500T/M, 700T/M, 1000T/M, respectively. produced yarns through this process were used as the samples for this experiment. Even though the shrinkage of fluffy yarn ATY(F) and ATY(D) becomes high as treated temperature rises and treated time lengthens, it is more affected by treated temperature then by treated time. In this experiment, produced fluffy yarn[ATY(D)] shows a little high values for temperature, but almost same values for higher temperatures. When we compare ATY(F) with ATY(D) fluffy yarn shows more natural fluffy yarn surface structure like natural cotton. The shrinkage of 700T/M twisted ATY(D) fluffy yarn show about 11% under treated temperature $180^{\circ}C$ and treated time 30min, and about 7% under $120^{\circ}C$ and 30min, respectively. But the shrinkage of 1000T/M fluffy yarn shoes about 9% and 6% under same conditions. Regarding treated time, tenacity and initial modulus of ATY(D) fluffy yarn rise high until 30min, but do not show much increase above 30min. Regarding treated temperature, tenacity and initial modulus of it rise high aboyer $140^{\circ}C$.

• Journal of Sericultural and Entomological Science
• /
• v.47 no.1
• /
• pp.41-47
• /
• 2005

Kayagum is a traditional musical instrument in Korea. Kayagum strings are usually made of raw silk. It needs good vibration and durability. This study was carried out to increase durability of the strings by chemical treatment and manufacture of silk/polyester and silk/wild silk compound yarn. In this study, we used MKW-810(water solube acrylic adhesive)and polyvinyl alcohol as a adhesive. Before the twisting, the raw silk wet on the string manufacture process. The adhesive reagent were added in this process. And compound yarn were prepated by domestic silk, polyester and wild silk(antheraea pernyi) for make of Kayagum strings, respectively. The result are as follows. 1. Tenacity and elongation of the strings are almost same between none and chemical treatment. However number of extension cycling to breaks of the strings was largely increased by chemical treatment. Number of extension cycling to breaks of the strings is very important and useful item to check durability of the strings. The stiffness of the strings were almost same between none and adhesive treatment 2. Tenacity of the silk/polyester strings is largely decreased by increasing of polyester portion, but elongation of the silk/polyester strings increased. However tenacity of the silk/polyester(mono filament) strings are higher than that of silk strings. 3. Tenacity of the domestic silk/wild silk strings is largely decreased by increasing of wild silk portion, but elongation of the domestic silk/wild silk strings is almost same among silk and domestic silk/wild silk strings.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.5
• /
• pp.532-542
• /
• 2020

This study was undertaken to identify effects of the peer group reading program (PGRP) on the tenacity, self-resilience, and adaptation to university life of new entrants to the university. This was a non-equivalence control group quasi-experimental research study design. The subjects examined were entrants at the S University. The experimental group was provided the PGRP, and the control group was provided a general program for 13 weeks. The PGRP consisted of three or four students per group. Each group read one book for one week. Subsequently, all students gathered and presented their reading reports and discussed their comments, once a week. Data were analyzed using Chi-square test and t-test to compare the differences between both groups. A total of 73 subjects were included in the study: 34 in the experimental group and 39 in the control group. There were no significant differences in the general characteristics between the groups. Furthermore, no significant differences were observed between both groups before the intervention; however, the experimental group showed improved tenacity (p<0.01) and self-resilience (p=0.020) after the intervention, which were significantly different between both groups. Our results indicate the requirement to develop and apply various reading programs for improving the personality, self-resilience, and college life adaptability of university entrants.