• Journal of the Microelectronics and Packaging Society
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• v.26 no.3
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• pp.43-49
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• 2019

In this study, a new approach using graphene oxide (GO) powder-composited Sn-3.0Ag-0.5Cu(in wt.%) solder paste for improving the bending reliability of solder joints between a flexible substrate and small outline package (SOP) was suggested. The GO addition slightly affected the melting temperature, however, the change in the melting temperature was not significant. Meanwhile, we observed the addition of GO could suppress IMC growth and IMC thickness of solder joint during the reflow process. Moreover, the cyclic bending test was also performed for evaluation of reliability in solder joint and we could improve the cyclic bending reliability of solder joint by adding GO powders. For 0.2 wt.% of GO added to the solder joint, the bending lifetime was increased to 20% greater than that without GO. Pull strength and ductility of the solder joint with GO were also higher than those of the joint without GO and it was assumed that this effect by adding GO could contribute to improve cyclic bending reliability of solder joint.

• Journal of Korea Port Economic Association
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• v.30 no.1
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• pp.159-173
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• 2014

This study is key competence port logistics companies analyze the priorities of evaluation factors. key competence index of NCS(National competency standard) was designed on the basis of the research model. The priorities of evaluation factors were analyzed using AHP method. The results of the analysis of 1 layer's key competence priorities are as follows: Interpersonal skills(0.217), communication skills(0.153), ability to develop problem(0.148), ability to understand the organization(0.103), and resource management skills(0.090), self-development ability and professional ethics(0.070), information skills(0.065), technical skills(0.049), numeracy skills(0.035).

• Journal of the Korea Society of Computer and Information
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• v.26 no.11
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• pp.1-9
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• 2021

3D-NAND flash memory provides high capacity per unit area by stacking 2D-NAND cells having a planar structure. However, due to the nature of the lamination process, there is a problem that the frequency of error occurrence may vary depending on each layer or physical cell location. This phenomenon becomes more pronounced as the number of write/erase(P/E) operations of the flash memory increases. Most flash-based storage devices such as SSDs use ECC for error correction. Since this method provides a fixed strength of data protection for all flash memory pages, it has limitations in 3D NAND flash memory, where the error rate varies depending on the physical location. Therefore, in this paper, pages and layers with different error rates are classified into clusters through the K-means machine learning algorithm, and differentiated data protection strength is applied to each cluster. We classify pages and layers based on the number of errors measured after endurance test, where the error rate varies significantly for each page and layer, and add parity data to stripes for areas vulnerable to errors to provides differentiate data protection strength. We show the possibility that this differentiated data protection policy can contribute to the improvement of reliability and lifespan of 3D NAND flash memory compared to the protection techniques using RAID-like or ECC alone.

• Korean Journal of Construction Engineering and Management
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• v.20 no.1
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• pp.41-51
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• 2019

With the aging of the population and the slowdown of the job market, elderly workers make up a large portion of the construction workforce. Also, due to the nature of the construction industry, where outdoor work is frequent, the weather has a more sensitive impact on elderly workers than on younger ones. The study aims to analyze the degree of weather risks exposed to elderly workers in the construction industry using the measure of work loss days. To that end, construction accidents that affected 28,514 elderly workers in seven cities from 2012 to 2016 (a total of 12,789 days) were analyzed to calculate work loss days per different weather factors. The results show that the elderly workers were seriously affected when the temperature was between $-12^{\circ}C$ and $-10^{\circ}C$, humidity between 55% and 60%, precipitation between 128mm and 181mm, and wind speed between 5.5m/s and 6.5m/s, with the highest work loss days. The combined effects between the weather factors were also analyzed to identify the conditiosn that leaded to high work loss days of elderly workers. This study contributes to effective safety management and pleasant working environment between weather factors and shedding light on the relationship between weather factors and work loss days of elderly workers.

• 재활복지
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• v.22 no.1
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• pp.87-114
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• 2018

The purpose of this study is to identify through empirical analysis about factors affecting the period of job maintenance of workers with cerebral palsy. Based on this, workers with cerebral palsy are looking for ways to maintain their job continuously. For this purpose, this study identifies the general characteristics and verify the affect of demographic factors, disability-related factors, employment-related factors, and social environment factors on the job maintenance period of workers with cerebral palsy. For the analysis, frequency analysis, descriptivel analysis, T-test and One-way Anova was conducted for 233 persons with cerebral palsy. The results of the study, of 17 variables of the four factors affecting the job maintenance period, 15 variables obtained statistically significant results. First, the demographic variables were age, household income, marital status, and education level. Second, the disability-related variables were disability grade, disability cause, and communication ability. Third, the employment-related variables were wage, employment type, disability-related organizations and companies, job type, job training, and qualification. Fourth, the social environment variables were assistive technology devices, and labor support personnel services.

• 재활복지
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• v.21 no.1
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• pp.97-119
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• 2017

The objective of this study is to understand the influence of discrimination experience on life satisfaction of the employed hearing-impaired, and also to verify the mediating effects of self-esteem on relations between discrimination experience and life satisfaction. To achieve this objective, the data of the 8th Panel Survey of Employment for the Disabled was used, and then the extracted data of 234 employed hearing-impaired persons was used for analysis. The results of this study are like below. First, discrimination experience showed negative(-) relations with self-esteem and life satisfaction while self-esteem showed positive(+) relations with life satisfaction. Second, when the perception of discrimination experience was low, the life satisfaction was high. Third, the mediating effects of self-esteem were verified on relations between discrimination experience and life satisfaction. Marital status, health, social-economical position has effected on life satisfaction. Based on such results of the study, suggestions were made to increase life satisfaction of the hearing-impaired.

• Korean Journal of Family Social Work
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• no.57
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• pp.125-157
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• 2017

The purpose of this study was to analyse effects of public support for single-parent family for adolescent single-parent who experienced social exclusion and social network. This study utilized a part of National Youth Policy Institute's 'Research on the Actual Condition of the Adolescent Pregnancy, Birth and Rearing Children'. Participants of the study were 262 adolescent single-parents at the age of 24 and below. In order to understand the effect, this study verified the moderating effect of public support for single-parent family in the context of social exclusion and social network on parental attitude and behavior(parenting efficacy, parenting stress, negative parenting behavior). Results of this study are as follows; First, Nearly half of adolescent single-parent has economic hardship in original family and most they lived with preschool children on unemployed state that the average monthly income of them was about 600,000 won. It means that their financial independence difficult. Second, family support was only significant factor for parenting efficacy and positive relationship with family and acquaintances was major influence factor for causing positive parental behavior of adolescent single-parent. As a result, social network was verified more important factor than social exclusion on parental attitude and behavior. Lastly, public support for single-parent family was confirmed as social mitigation mechanism that has the moderating effect of social exclusion and social network on parental attitude and behavior.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.5
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• pp.64-78
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• 2019

This paper explores key factors affecting taxi travel using global positioning system(GPS) data in Seoul, Korea, considering spatial dependence. We first analyzed the travel characteristics of taxis such as average travel time, average travel distance, and spatial distribution of taxi trips according to the time of the day and the day of the week. As a result, it is found that the most taxi trips were generated during the morning peak time (8 a.m. to 9 a.m.) and after the midnight (until 1 a.m.) on weekdays. The average travel distance and travel time for taxi trips were 5.9 km and 13 minutes, respectively. This implies that taxis are mainly used for short-distance travel and as an alternative to public transit after midnight in a large city. In addition, we identified that taxi trips were spatially correlated at the traffic analysis zone(TAZ) level through the Moran's I test. Thus, spatial regression models (spatial-lagged and spatial-error models) for taxi trips were developed, accounting for socio-demographics (such as the number of households, the number of elderly people, female ratio to the total population, and the number of vehicles), transportation services (such as the number of subway stations and bus stops), and land-use characteristics (such as population density, employment density, and residential areas) as explanatory variables. The model results indicate that these variables are significantly associated with taxi trips.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.81-86
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• 2019

Metal oxide/graphene composites have been known as promising functional materials for advanced applications such as high sensitivity gas sensor, and high capacitive secondary battery. In this study, tin dioxide ($SnO_2$) nanostructures were grown on chemically synthesized graphene nanosheets using a two-zone horizontal furnace system. The large area graphene nanosheets were synthesized on Cu foil by thermal chemical vapor deposition system with the methane and hydrogen gas. Chemically synthesized graphene nanosheets were transferred on cleaned $SiO_2$(300 nm)/Si substrate using the PMMA. The $SnO_2$ nanostuctures were grown on graphene nanosheets at $424^{\circ}C$ under 3.1 Torr for 3 hours. Raman spectroscopy was used to estimate the quality of as-synthesized graphene nanosheets and to confirm the phase of as-grown $SnO_2$ nanostructures. The surface morphology of as-grown $SnO_2$ nanostructures on graphene nanosheets was characterized by field-emission scanning electron microscopy (FE-SEM). As the results, the synthesized graphene nanosheets are bi-layers graphene nanosheets, and as-grown tin oxide nanostructures exhibit tin dioxide phase. The morphology of $SnO_2$ nanostructures on graphene nanosheets exhibits complex nanostructures, whereas the surface morphology of $SnO_2$ nanostructures on $SiO_2$(300 nm)/Si substrate exhibits simply nano-dots. The complex nanostructures of $SnO_2$ on graphene nanosheets are attributed to functional groups on graphene surface.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.199-211
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• 2021

This study suggests an alternative for solving quality-of-life problems of an aging workforce by seeking ways to utilize an aging workforce in corporations and society. This research empirically analyzed data from the 6th panel data of aging. Study results are as follows. First, it was confirmed that job satisfaction of aging manpower plays a mediating role in the relationship between quality of life and the job characteristics of an aging workforce. Second, it was found that the wage level of regular workers had a significant effect on job satisfaction and quality of life, and the job satisfaction of regular workers was mediated between wage level and quality of life. On the other hand, the wage level of non-regular workers did not have any effect on job satisfaction and quality of life. The results of this study suggest the necessity for companies to recognize the use of an aging workforce to improve social value. Furthermore, our results provide implications for domestic firms and government policymakers on how to use a domestic aging workforce and how to utilize regular and non-regular workers.