• Journal of KSNVE
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• v.5 no.4
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• pp.503-514
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• 1995

In the case of performing experimental modal analysis(EMA) and finite- element analysis(EFA) for a whole structure of automotive body that is composed of many complex parts, a trouble may arise from the calculation time, the capacity of memory in computers and the experimental conditions, etc. In this paper, for the vibrational analysis of automotive body model, the efficient modal synthesis method by means of dividing the whole structure into two parts and performing EMA and FEA for each part is studied. In addition, the method based on Lagrange interpolation is proposed for approximating rotational degrees-of-freedom information and linking FEA with EMA. In result, by measuring translational degrees-of-freedom information of only few points and adopting only few modes, the linking method based on Lagrange interpolation turned out to be efficient and accurate in the low frequency range.

• Journal of Industrial Technology
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• v.35
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• pp.35-39
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• 2015

One of the purposes of the study was to investigate and compare the physical properties(depth of light cure, degree of conversion, water absorption) of 4 kinds of composit resins prepared in this lab; Bis-GMA based, Bis-EMA based, Bis-GMA/UDMA based, and Bis-EMA/UDMA based composit. Another aim was to compare the physical properties of the composit resins with those of the commercialized products(Charmfil flow(Denkist), Quadrant flow(CAVEX)) in market. All of the composit resins and the commercialized products showed almost same values of the physical properties. It was found that all of the composit resins prepared in this lab satisfied the physical properties specified in ISO 4049.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.894-900
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• 1998

An interphase between carbon fiber and epoxy matrix was introduced to increase impact strength of carbon fiber reinforced composites (CFRC) without sacrificing the interlaminar shear strength. Flexible polymers, I. e., MVEMA (poly(methyl vinyl ether-co-maleic anhydride)) and EMA(poly(ethylene-co-maleic anhydride)), which have reactive functional groups were considered as interphase materials. Weight hain of MVEMA and EMA onto the surface of carbon fibers was evaluated by changing the parameters of electrodeposition process. Electrodeposition mechanism of polymers which have anhydride functional group was identified by IR spectroscopy, that is, the generation of $RCOO^-$ functional group by the attack of hydroxide anion in the basic solution was observed. The weight gain was increased by increasing concentration of polymers, current density, and electrodeposition time. However the excess generation of oxygen gas decreased the weight gain by removing the deposited polymers. Washing in the running water easily removed the deposited polymers which are on the fiber surface without bonding, as a results, only 0.5 wt% of deposited polymers are remained.

• Journal of the Korea Convergence Society
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• v.12 no.5
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• pp.313-326
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• 2021

This study was to introduce ecological momentary assessment and show how to apply it to real-world research. As preliminary study for sustainable development, the result explained growth model using senior's longitudinal data and suitability of multi-level model in EMA data with regression analysis. The total variance of dependent variable was determined through a base model with only intercept and approximately 47% of total variance was caused by individual differences and 53% by time point differences. Second model was used to verified that each individual has a different effect on the senior vitality and effect on time was not significant. This is because it is the result of a preliminary stage where treatment is not involved and there is no significant change in process of collecting EMA data without external intervention. Third model that add gender as an independent variable showed significant change in both time and gender. Finally compared the PRD for each model and found models that without gender variables fit the data more effectively. This suggests that studies dealing with longitudinal data such as EMA data should adopt multi-level model that can measure individual characteristics, taking into account respondents' time and context.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2003.05a
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• pp.422-427
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• 2003

고분자 물질의 대부분은 유기용매를 사용하여 제조되는 경우가 일반적이었다. 이들 중에는 용제형 아크릴계 고분자는 점착강도, 내습성, 내수성 그리고 내열성 등이 우수하여 페인트, 접ㆍ점착제, 섬유 등의 산업전반에 이용되고 있으나 용제사용에 따른 화재의 위험성과 환경적인 문제점 때문에 규제의 대상이 되고 있다.(중략)

• Korean Journal of Acupuncture
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• v.29 no.4
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• pp.554-562
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• 2012

Objectives : The purpose of this research is to verify the effects of the Electromagnetic acupuncture(EMA) on BL15 by Pupil size variability(PSV) which is directly related to the activation of the Autonomic Nervous System. Methods : Thirty male subjects participated in this study and were divided into three groups(non-stimulated, manual acupuncture and EMA group). The size of pupil was measured in the cube place of $60{\times}60{\times}60$ cm in order to avoid the effect of the surrounding circumstances. All subjects were measured the size of left pupil about 200sec in the constant illumination. Results : We observed the decrease in PSV of manual acupuncture group compared to non-stimulation group, but it was not significant statistically(p>0.05). The decrease in PSV of EMA group was observed in comparison to two groups, and we confirmed the result of significant difference statistically(p<0.05). Conclusions : We concluded that EMA treatment method is enough to activate in the parasympathetic nerve system by inducing the biotransformation.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.10
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• pp.1387-1393
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• 2014

This study aimed to estimate genetic correlation between carcass grading and retail productivity traits and to estimate the correlated response on retail productivity traits through selection for carcass grading traits in order to assess the efficacy of indirect selection. Genetic parameters were estimated with the data from 4240 Hanwoo steers using mixed models, and phenotypes included carcass weight (CWT), back fat thickness (BFT), eye muscle area (EMA), marbling (MAR), and estimated lean yield percentage (ELP) as the carcass grading traits, and weight and portion of retail cuts (RCW and RCP), trimmed fats (TFW and TFP) and trimmed bones (TBW and TBP) as the lean productivity traits. The CWT had positive genetic correlations with RCW (0.95) and TFW (0.73), but its genetic correlation with RCP was negligible (0.02). The BFT was negatively correlated with RCP (-0.63), but positively correlated with TFW and TFP (0.77 and 0.70). Genetic correlations of MAR with TFW and TFP were low. Among the carcass grading traits, only EMA was positively correlated with both RCW (0.60) and RCP (0.72). The EMA had a relatively strong negative genetic correlation with TFW (-0.64). The genetic correlation coefficients of ELP with RCP, TFW, and TFP were 0.76, -0.90, and -0.82, respectively. These correlation coefficients suggested that the ELP and EMA might be favorable traits in regulating lean productivity of carcass.

• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.627-632
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• 2016

Ethyl methacrylate (EMA) monomer coupling onto the polyvinylidene fluoride (PVDF) film surface was attempted to enhance the interfacial adhesive force between PVDF-polyvinyl chloride (PVC) bilayer films via dielectric barrier corona discharge. The interfacial forces were quite enhanced when PVDF films were treated by corona discharge in an EMA 1% atmosphere. The contact angle of PVDF films decreased due to corona treatment. X-ray photoelectron spectroscopy (XPS) analysis showed that the carbon and oxygen content of the PVDF film surface increased with corona discharge while the fluoride content decreased. The curve fitting of XPS $C_{1s}$ peaks revealed that the non-polar C-C bonded carbon and oxygen-bonded carbon increased gradually with corona treatment, while the fluorine-bonded carbon decreased.

• Polymer(Korea)
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• v.36 no.5
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• pp.564-572
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• 2012

A terpolymer of vinylbenzyl chloride-co-ethyl methacrylate-co-styrene (VBC-EMA-St) was prepared for membrane capacitive deionization (MCDI) by radical polymerization and amination reaction of various amination times. Nonfluoro aminated VBC-EMA-St anion-exchange membranes were characterized by Fourier transform infrared (FTIR) spectrometry. Molecular weight, polydispersity and thermal stability were obtained by gel permeation chromatography (GPC) and thermogravimetric analysis (TGA). The basic properties such as water uptake, ion exchange capacity, electrical resistance and CDI charge-discharge current were measured. The optimal values of ion exchange capacity, water uptake, electrical resistance and molecular weight of synthesized anion-exchange membrane were 1.69 meq/g, 23.7%, 1.61 ${\Omega}{\cdot}cm$ and $3.4{\times}10^4$ g/mol, respectively. As compared with conventional membrane, the pattern of cyclic charge-discharge current of synthesized anion-exchange membrane indicated efficient electrosorption and desorption.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.2
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• pp.111-118
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• 2022

An electro-mechanical actuator (EMA) is an actuator that combines an electric motor with a mechanical power transmission elements, and it is suitable for urban air mobility (UAM) in terms of design freedom and maintenance. In this paper, the author presents the research results of the EMA that controls the rotor blade pitch angle of UAM. The actuator is based on an inverted roller screw and controls the blade pitch angle through a two-bar linkage. The dynamic equations for the actuator alone and the blade pitching motion with actuator were derived. For the latter, the equivalent moment of inertia is variable depending on the link angle due to the two-bar linkage. The variations of the equivalent moments of inertia are analyzed and compared in terms of the nut motion and the blade pitch motion. For an example model, the variation of the equivalent moment of inertia of the former is smaller than the latter, so it is judged that the dynamic equations derived from the point of view of the nut motion is suitable for the controller design.