• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.3
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• pp.44-51
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• 2016

This paper presents the characteristics of the energy absorption in an expansion tube type impact absorber that is applied to a high weight drop tester and the use of a response surface methodology to predict the impact energy absorption. In order to identify the characteristics of the energy absorption, a set of finite element analysis was conducted with Abaqus Explicit. Moreover, the ISCD-II sampling method and a first order polynomial were used to build a response surface. As a result, we demonstrated that the impact energy could be controlled by four main design variables, namely an expansion pipe's thickness, inner radius, pressing die's expansion angle and expansion ratio. Additionally, we observed the relationship between the four main design variables and the impact energy absorbing time, displacement, and maximum impact force.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.3
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• pp.76-82
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• 2017

Recently, the material industry in the world has started appreciating the value of new materials that can overcome the limitation of steel material. In particular, new materials are expected to play a very important role in the future industry, demonstrating superior performance compared to steel in lightweight materials and ability to maintain in high temperature environments. Carbon materials have recently increased in value due to excellent physical properties such as high strength and ultra lightweight compared to steel. However, they have not overcome the limitation of productivity and price. The carbon materials are classified into various composites depending on the purpose of use and the performance required. Typical composites include carbon-glass, carbon-carbon, and carbon-plastic composites. Among them, carbon-carbon composite technology is a necessary technology in aviation and space, and can be manufactured with high investment cost and technology. In this paper, in order to find the optimal conditions to achieve productivity improvement and cost reduction of carbon material densification process, the correlation between each process parameters and results of densification is first analyzed. The main process parameters of the densification process are selected by analyzing the correlation results. And then a certain linear relationship between major process variables and density of carbon materials is derived by performing a regression analysis based on the historical production result data. Using the derived casualty, the optimal management range of major process variables is suggested. Effective process operation through optimal management of variables will have a great effect on productivity improvement and manufacturing cost reduction by shortening the lead time.

• Journal of Korean Home Economics Education Association
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• v.5 no.1
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• pp.31-43
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• 1993

The purpose of this study was to investigate middle school students’perception about Home Economics Education in order to provide the basic materials to improve Home Economics curriculum. For this purpose reviewing literatures and empirical research were conducted. the subjects were 661(fourteen-year-ole(8th graders) enrolled in middle school in Seoul and Gyeongsang-nam-do. Statistical methods adopted for data analysis were frequencies, mean standard deviation, ONEWAY ANOVA, Chi-square. Major findings were as follows: 1. The middle school students’perception about Home Economics Education differed with sex of subjects. That is, girl students’perception was higher than boy students’perception. 2. The middle school students’perception about Home Economics subject varied across parents’education level. 3. There was no significant difference in the middle school students’perception about Home Economics Education according to existence of mother’s Job. 4. There was a significant difference in the middle school students’perception about Home Economics Education according to region. That is the perception about the contents of eating life role was high in rural and the daily life as a consumer and resources application was high in Seoul. 5.The middle school students’perception about Home Economics Education varied across subject distinction. That is the perception of boy students who chose Industrial Arts$.$Home Economics subject was high.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.234-241
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• 2010

Industrial combustible waste is very valuable source for refuse derived solid fuel since its heating value is usually over 3,000kcal/kg. Especially, synthetic high molecular compound which is high of productivity and heating value is used as raw material in many cases. Film type plastic has been widely used for producing RPF because their shaping is easy and they has high heating value. On the other hand, the possibility of various type of waste as a source for RPF in this study. It has been found that resin compound drived and tire derived solid fuel showed more than 6,000kcal/kg of heating value. But the heating value decreased by adding paper and wood waste.

• 대한공업교육학회지
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• v.39 no.1
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• pp.47-65
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• 2014

The purpose of this study is to investigate the university academic achievements on the high school graduates of specialized vocational high school and general high school selected by the university admissions officer system. The implications of this study will contribute to improve development of university admission through the analysis of university admission achievements and correlation between university admission factors and university academic achievements. Participants of this study were university students selected by admission officer system in 2011 and have enrolled in the university for 6 semesters at A university. The results of this study are as follows: First, when it comes to the grades of university admission factors, graduates from specialized vocational high school outperformed those from general high school. Second, when it comes to the correlation between university academic achievements and university admission factors, graduates from specialized vocational high school slightly outperformed those from general high school. Third, when it comes to the correlation between university academic achievements and university academic achievements, graduates from specialized vocational high school showed poorer performance than those from general high school in overall courses and liberal arts courses. However, in major courses, graduates from specialized vocational high school outperformed those from general high school. Finally, when it comes to the development of university academic achievements, both of them showed a tendency of being improved as they advanced through school. Based on the findings of this study, several implications can be made as follows: First, it is necessary to improve the application ratio and application method of university admission factors. Second, it is required to provide preparatory courses of university to help graduates from specialized high school get adapted to university course of study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1534-1539
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• 2010

This study carried out dental checkup targeting 251 students in the 1st grade of S middle school and 220 students in the 1st grade of S high school in Seoul Metropolis. The results are as follows. As for the experience of dental hypersensitivity to oral symptoms in middle-and-high school students, 23.2% of high school students had experience of painful tooth when drinking or eating cold and hot beverage or food, compared to 14.3% of middle school students, and showed significant difference($\chi^2=6.08$, p<.05). As for the experience of painful teeth, 9.1% of high school students had experience of being sore, aching, and painful in the teeth, compared to 4.4% of middle school students, and showed significant difference($\chi^2=4.23$, p<.05). As a result of the oral health behavior in middle-and-high school students, 48.6% of middle school students were indicated to be higher than 26.4% of high school students in the experience of having ever gone to dentist for the past 1 year, and showed statistically significant difference($\chi^2=24.56$, p<.001). As for the period of toothbrushing during one day, 68.5% of middle school students brushed teeth after having breakfast($\chi^2=6.39$, p<.05) more than 57.3% of high school students. After having lunch, 16.8% of high school students brushed teeth more than 7.2% of middle school students, and showed statistically significant difference($\chi^2=10.58$, p<.01). As a result of judging dental checkup in middle-and-high school students, 44.1% of high school students had dental caries($\chi^2=25.36$, p<.001) more than 22.3% of middle school students. 9.6% of middle school students had tooth loss more than 4.1% of high school students, and showed statistically significant difference($\chi^2=5.39$, p<.05).

• Journal of Environmental Health Sciences
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• v.32 no.5 s.92
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• pp.506-514
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• 2006

The objectives of this study were to evaluate personal exposure estimated using a time activity pattern and microenvironmental model. The study was carried out for 44 children attending a primary school nearby the lines (school A) and 125 children attending a school away from 154 kV power lines (school B). For children attending school A, the estimated personal level was a little weak correlated with the measured level($Pearson\;r\;=0.34{\sim}0.35$). For children attending school B, the correlation was very low ($Pearson\;r\;=\;0.09{\sim}0.16$) using the TW A Model II, otherwise, TWA Model II-I which considered the average residential MF level according to the distance from the power line and home explained $39{\sim}53%$ of the correlation in MF personal exposures. The estimated personal exposure level was very well represented by the measured exposure level using TWA Model II-2 which consisted on spot and 24 h stationary measurements at subject's home ($Pearson\;r\;=\;0.65{\sim}0.85$). In conclusion, personal magnetic field expsoure estimated using a TWA Model II-2 should be provided for a reasonable estimate of measured exposure in schoolchildren living near the power line.

• Journal of Microbiology and Biotechnology
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• v.22 no.9
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• pp.1202-1207
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• 2012

A gene, ClCDA, encoding chitin deacetylase from Colletotrichum lindemuthianum, was optimized according to the codon usage bias of Pichia pastoris and synthesized in vitro by overlap extension PCR. It was secretorily expressed in P. pastoris GS115 using the constitutive expression vector pHMB905A. The expression level reached the highest with 110 mg/l culture supernatant after 72 h of methanol induction, which comprised 77.27 U/mg chitin deacetylase activity. SDS-PAGE, mass spectrometry, and deglycosylation assays demonstrated that partial recombinant protein was glycosylated with an apparent molecular mass of 33 kDa. The amino acid sequences of recombinant proteins were confirmed by mass spectrometry.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.170-185
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• 2016

The purpose of this study was to investigate the relationship among instructor's non-verbal communication, emotional reaction, and self-efficacy. By using convenience sampling method of non-provability sampling, 258 student athletes from S and D cities were selected for a questionnaire survey. The 184 returned surveys were analyzed with structural equation modeling through SPSS 22.0 and AMOS 22.0 statics program. The study results are summarized as follows. First, instructor's non-verbal communication has a positive influence on emotional reaction of high school student athletes. Second, high school student athletes experiencing emotional reactions by instructor have a positive influence on self-efficacy. Third, instructor's non-verbal communication does not influence self-efficacy of high school student athletes directly. Fourth, emotional reactions of high school student athletes experienced by instructor's non-verbal communication have a mediating effect on self-efficacy. Fifth, neither gender nor exercise period has a moderating effect on the relationship between non-verbal communication, emotional reactions, and self-efficacy.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.47 no.2
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• pp.30-39
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• 2024

This study introduces a novel approach for identifying potential failure risks in missile manufacturing by leveraging Quality Inspection Management (QIM) data to address the challenges presented by a dataset comprising 666 variables and data imbalances. The utilization of the SMOTE for data augmentation and Lasso Regression for dimensionality reduction, followed by the application of a Random Forest model, results in a 99.40% accuracy rate in classifying missiles with a high likelihood of failure. Such measures enable the preemptive identification of missiles at a heightened risk of failure, thereby mitigating the risk of field failures and enhancing missile life. The integration of Lasso Regression and Random Forest is employed to pinpoint critical variables and test items that significantly impact failure, with a particular emphasis on variables related to performance and connection resistance. Moreover, the research highlights the potential for broadening the scope of data-driven decision-making within quality control systems, including the refinement of maintenance strategies and the adjustment of control limits for essential test items.