• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.209-213
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• 1998

In the paper, we present the design procedure and analysis the fundamental characteristics for Linear DC Motor(LDM) using permeance method and finite element method (FEM). Designed LDM is made of two permanent magnets, three iron core and armature windings. For the design of the LDM, first of all it is necessary to calculate the air gap flux density and thrust force, after that to determine core size, the numbers of winding turns, winding width, etc. To demonstrate the method of caculation yields the right results, we used Maxwell program package for computing magnetic fields. Finally we find that the proposed design procedure in this paper is effective to design of LDM.

• Nuclear Engineering and Technology
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• v.29 no.2
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• pp.138-147
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• 1997

Korean-made alloys 600 and 690 tubes were evaluated by flare tests according to ASTM standards, and acting stresses during the test ore analyzed. All the tubes, including alloys 600 and 690 tubes with various heat treatment conditions, satisfied the requirement with 30 or 35750.D expansion. Axial stresses in alloy 690 tubes were higher than those in alloy 600 ones and the gap increased gradually with flaring percentage(F.P, %). Assuming the tubes as the rigid-perfectly plastic body, a stress equation was obtained using modified Tresca's yield criterion. Also microstructural change of the flared tubes was discussed with the acting stresses.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.4
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• pp.261-270
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• 2004

The purpose of this experiment was to examine the histological changes and the pattern of expression of type I, II collagen in the elongated area by distraction osteogenesis in the rabbit mandible. Sixteen rabbits weighing 2.5kg-3kg were used for this experiment. Experimental group was distracted at the rate of 0.7mm, twice/day for 7days, and control group was only osteotomized. After 5 days latency, osteotomic site is distracted for 7days. Consolidation period is 28days. The animal was sacrificed at the 3rd, 7th, 14th, 28th day after the operation. The distracted bone was examined by histological analysis and RT-PCR analysis. The results were summarized as follows: 1. Experimental group was observed that the gaps between the distracted bone edges were occupied by new bone. 2. Expression of Type I collagen were detected throughout the experiment in both groups and Expression of Type I collagen were markedly increased during distraction and consolidation period in experimental group than control group. 3. Expression of Type II collagen were detected throughout the experiment in both groups and expression of Type II collagen were maintained at high level during distraction and consolidation period in experimental group than control group. From these results, in contrast to type II collagen, type I collagen seemed to be more expressed by mechanical stimuli during distraction and consolidation period. The predominent mechanism of new bone formation in the distraction gap was intramembranous bone formation, but some of the regenerated bone was formed by endochondral ossification.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1519-1526
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• 2023

For the first time Aluminium-BariumeZinc oxide nanocomposite (ZABONC) was synthesized by solution combustion method where calcination was carried out at low temperatures (600℃) to study the electromagnetic (EM) (X/γ) radiation shielding properties. Further for characterization purpose standard techniques like PXRD, SEM, UV-VISIBLE, FTIR were used to find phase purity, functional groups, surface morphology, and to do structural analysis and energy band gap determination. The PXRD pattern shows (hkl) planes corresponding to spinel cubic phase of ZnAl₂O4, cubic Ba(NO₃)₂, α and γ phase of Al₂O₃ which clearly confirms the formation of complex nano composite. From SEM histogram mean size of nano particles was calculated and is in the order of 17 nm. Wood and Tauc's relation direct energy band gap calculation gives energy gap of 2.9 eV. In addition, EM (X/γ) shielding properties were measured and compared with the theoretical ones using standard procedures (NaI (Tl) detector and multi channel analyzer MCA). For energy above 356 keV the measured shielding parameters agree well with the theory, while below this value slight deviation is observed, due to the influence of atomic/crystallite size of the ZABONC. Hence synthesized ZABONC can be used as a shielding material in EM (X/γ) radiation shielding.

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.2
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• pp.204-216
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• 1999

Failure physics and statistical lifetime analysis constitute the two extreme ends of the reliability engineering spectrum, and studies that relate failure mechanisms to failure distributions have been near non-existent. This paper is an attempt to stimulate interest to fill the gap between the two extremes and proposes an approach of combining them through i) developing a failure mechanism model, ii) generating failure times by Monte Carlo simulation with the model, iii) deriving the failure time distribution and evaluating the product reliability, and iv) improving the product reliability by the sensitivity analysis. An application of the proposed approach to the BGA(Ball Grid Array) surface mount package is also provided.

• Korea Journal of Hospital Management
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• v.26 no.3
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• pp.43-55
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• 2021

Purposes: The purpose of this study is to confirm the effect of mother's nationality on screening rates for infants and children health screening. We intend to find out if there is a difference in health level between infants of multicultural families and infants of domestic families, and contribute to policies to enhance future national health levels by providing information on them. Methodology: Data for those who received the first infant and children health screening between 2012 and 2018 were obtained from the National Health Insurance Service(NHIS) DB. Frequency analysis, chi-square test and logistic regression analysis were performed with the SAS 9.4 program, and the case where all the 1st to 3rd checkups were completed was defined as type I, and the case of all the 1st to 7th checkups completed, type II. Findings: Complete screening rates for type I and type II were 45.8% and 20.0%, respectively. Especially, complete screening rate of infants whose mothers nationality is foreign is only 3-4th of that of domestic mothers, and it also differed according to nationality. Practical Implications: The difference in the screening rate according to the mother's nationality is likely to lead to a health gap between multicultural families and domestic families. It is necessary to promote and encourage proper monitoring and health management through continuous health screening for infants and children.

• Journal of Family Relations
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• v.22 no.3
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• pp.47-72
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• 2017

Objectives: Do husbands with working wives share domestic labor more equally than husbands with unemployed housewives? Is the husband's contribution sufficient enough to satisfy his wife? These questions have long inspired many researchers to find ways to more accurately estimate husband's domestic contributions and narrow the emotional gap following the different threshold of satisfaction within couples, but not without some limits. This study attempted to figure out an answer to the above-mentioned subject by using time diaries of Korean married couples with a preschooler as their first-born child and relying on the typology of husbands' sharing of housework and childcare, which allowed me to overcome some limitations of prior research. Method: I analyzed a total of 1,716 diaries of 858 married couples from 2014 Korea Time Use Survey with descriptive statistics, t-test, cluster analysis, and multinomial logit. Results: Analytic results showed that husbands in dual-earner households did share domestic labor more equally than husbands in single-earner households, but there were different types of husband's contribution depending on time they spent in housework and childcare. While more than half of husbands with employed wives shared more or less than ten percent of domestic labor, the rest were divided into one group of husbands who shared both housework and childcare more heavily and evenly, and another group who were mainly involved in childcare duties. It is interesting that husbands who made the least contributions to domestic labor were not the ones with the lowest level of satisfaction with their sharing of household labor, whereas their wives were deeply dissatisfied, leading to a huge emotional gap within couples. Conclusion: Identifying factors associated with the three different types allowed me to find a point of intervention to narrow the emotional gap that is likely to harm the marital relationship if left unattended to.

• Journal of Information Science Theory and Practice
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• v.9 no.2
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• pp.18-32
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• 2021

Social media has become a popular source of information around the world. Previous studies explored different trends of social media news consumption. However, no studies have focused on Bangladesh to date, where social media penetration is very high in recent years. To fill this gap, this research aimed to understand its popularity trends during the period. For that reason, this work analyzes 97.67 million page likes and 3.48 billion interaction data collected from nine Bangladeshi news media's Facebook pages between December 2016 to November 2020. The analysis shows that the growth rates of page likes and interaction rates declined during this period. It suggests that the media's Facebook pages are gradually losing their popularity among Facebook users, which may have two more interpretations: Facebook's aggregate appeal as a news source is decreasing to users, or Bangladeshi media's appeal is eroding to Facebook users. These findings challenge the previous results, i.e., Facebook's demand as a news source is increasing with time. We offer four explanations of the decreased popularity of Facebook's news: information overload, exposure to incidental news, users' selective exposure and different aims of using Facebook, and conflict between media agendas and users' interests. Some theoretical and practical significance of the results has been discussed as well.

• Journal of Korea Water Resources Association
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• v.37 no.2
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• pp.87-96
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• 2004

The simulation results using i- V relationship of non-Darcy flow through tide embankment by Li et al.(1998) agree well to the observed data. The use of i- V relationship is applicable to the engineering practice and the correct input of porosity is necessary. The non-Darcy flow based on the pipe flow and Taylor's definition for mean hydraulics radius in rockfill material is applicable to the block and caisson materials. The correct calculation of flow through tide embankment enables the accurate calculation of velocity at final closing gap and the prediction of inner water level after tide embankment construction as well.

• Transactions of Materials Processing
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• v.22 no.1
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• pp.48-53
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• 2013

As the adoption of injection molding technology increases, injected-molded optical products require higher dimensional accuracy and optical stability than ever before. In the present study, four kinds of molding methods, i.e., conventional injection molding (CIM), injection/compression molding (ICM), rapid heat and cooling the mold(RHCM) and rapid injection/compression molding (RICM) were selected in order to investigate the optical anisotropy of a 7 inch Light Guide Plate(LGP) by examining the gap-wise distribution of birefringence and the extinction angle. The results indicate that the compression process can decrease flow-induced birefringence over the whole region and that rapid heating can decrease the birefringence level better than conventional molding. In addition, for the combination of compression and rapid heating a reversal flow was detected from the distribution of the extinction angle near the gate.