• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.4
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• pp.878-885
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• 2008

The FPDs(Flat Panel Displays) such as LCD(Liquid Crystal Display) and PDP(Plasma Display Panel) and OLED(Organic Light Emitting Diode), recently, have been substituted for CRT(Cathode Ray Tube) displays because they have a convex surface, small volume, light weight and lower electric power consumption. The productivity of FPDs is greatly dependent on the area of thin glass panel with 0.6 - 0.8mm thickness because FPDs are manufactured by cutting a large-scaled thin glass panel with patterns to the required product dimensions. So FPD's industries are trying to increase the area of thin glass panel. For example, the thin glass panel size of the 8th generation is 2,200mm in width, 2,600mm in length and 0.7mm in thickness. The air flows both in the thin glass panel and in the porous PE-plate surface were modeled and analyzed, from which a working condition was estimated. The thin glass panel on the porous PE-plate surface with self-lubricating characteristics was investigated and compared with that on the square duct floating bar surface with many holes of 1mm diameter when the thin glass panel contacts the floating bar surface due to malfunction of electric power supply.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.8
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• pp.3794-3803
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• 2013

The purpose of this study was to find out the relationships between emotional labour and depressive symptoms among nurses in university hospitals. Subjects were 514 nurses working at three university hospitals in Daejeon City, and the survey was a structured self- administered questionnaire based from April 1 until May 31 2012. As a results, the level of depressive symptoms by the subjects emotional labour level was significantly higher in the group with higher total average points of the emotional labour than the lower group, As for the correlation between the level of depressive symptoms and emotional labour factors, the depressive symptoms points showed significant positive correlation with the total points of the emotional labour. As a result of hierarchical multiple regression, age, leisure time, coffee consumption, subjective health status, physical burden of work, sense of satisfaction at work, fit to the job and emotional labour were selected as significant variables and related variables effecting the level of depressive symptoms. These variables' descriptive power was 39.4%, especially, it can be seen that 11.0% descriptive power increased by putting the emotional labor variables. The results above imply that there is significant relation between emotional labor and depressive symptoms and various variables such as socio-demographic characteristics, health-related behavior factors and job-related factors. Also, it can be seen that the emotional labour and depressive symptoms showed significant positive correlation. Therefore, the development and implementation of a program to control emotional labor appropriately should be required for lowering the level of depressive symptoms.

• The Journal of the Korea Contents Association
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• v.15 no.3
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• pp.352-361
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• 2015

Tea is one of the three most consumed drinks in the world along with coffee and cocoa, and it represents culture and tradition. There are more than 1,000 tea-related smartphone applications registered in the Apple App Store and Google Play. This study examined, for the consumers of the 20's, if there are differences in consumer preferences for tea-related applications based on gender, age, tea consumption amount and tea drinking duration. Based on surveys of 169 tea consumers, this study found that there were significant differences in consumer preferences for tea-related applications based on age and tea drinking amount. The applications of 'tea places,' 'entertainment,' and 'tea timer' were preferred by the consumers of 20's and 'etiquette,' 'tea ceremony,' 'teaware,'and 'tea information recording' were favored by the consumers of 30's and older. The consumers with higher drinking amount showed higher preferences for tea etiquette related applications. There were no significant differences for tea-related applications based on gender and tea drinking duration. The result of the study is expected to contribute to the development of tea related applications with higher appeals to consumers as well as traditional Korean drinks.

• Nutrition Research and Practice
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• v.12 no.4
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• pp.324-335
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• 2018

BACKGROUND/OBJECTIVES: We examined dietary fat intake and the major food sources by young children in Korea. SUBJECTS/METHODS: A total of 1,041 children aged 1-5 years were identified from the 2013-2015 Korea National Health and Nutrition Examination Survey. Data on total fat and fatty acid intake were obtained by a single 24-h dietary recall. Food sources were identified based on the amounts of total fat and fatty acids consumption according to each food. Fat and fatty acid intakes and their food sources were presented by age group (1-2-y, n = 401; 3-5-y, n = 640). Fat and fatty acid intakes were also evaluated according to socioeconomic characteristics. RESULTS: The mean intake of fat was $27.1{\pm}0.8g$ in the 1-2-y group and $35.5{\pm}0.7g$ in the 3-5-y group, and about 23% of the total energy was obtained from fat in both age groups. The mean intake of saturated fatty acids (SFA) was $10.5{\pm}0.3g$ in the 1-2-y group and $12.7{\pm}0.3g$ in the 3-5-y group, with the 1-2-y group obtaining more energy from SFA than the 3-5-y group (9.2% vs. 8.3%). The mean intake of polyunsaturated fatty acids (PUFA) was $6.3{\pm}0.1g$ in the total subjects, with $0.8{\pm}0.03g$ of n-3 fatty acids and $5.5{\pm}0.1g$ of n-6 fatty acids being consumed. Milk, pork, and eggs were major food sources of total fat, SFA, and monounsaturated fatty acids, and soybean oil was the main contributor to PUFA in both age groups. In the 1-2-y group, children in rural areas had significantly higher intake of PUFA and n-3 fatty acids than did those in urban areas. CONCLUSIONS: Our findings provide current information on dietary fat intake among young Korean children and could be used to establish dietary strategies for improvement of health status.

• The Journal of Industrial Distribution & Business
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• v.11 no.7
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• pp.29-40
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• 2020

Purpose: In modern society, many urban problems are occurring, such as aging, hollowing out old city centers and polarization within cities. In this study, we intend to apply big data and machine learning methodologies to predict depression symptoms in the elderly population early on, thus contributing to solving the problem of elderly depression. Research design, data and methodology: Machine learning techniques used random forest and analyzed the correlation between CES-D10 and other variables, which are widely used worldwide, to estimate important variables. Dependent variables were set up as two variables that distinguish normal/depression from moderate/severe depression, and a total of 106 independent variables were included, including subjective health conditions, cognitive abilities, and daily life quality surveys, as well as the objective characteristics of the elderly as well as the subjective health, health, employment, household background, income, consumption, assets, subjective expectations, and quality of life surveys. Results: Studies have shown that satisfaction with residential areas and quality of life and cognitive ability scores have important effects in classifying elderly depression, satisfaction with living quality and economic conditions, and number of outpatient care in living areas and clinics have been important variables. In addition, the results of a random forest performance evaluation, the accuracy of classification model that classify whether elderly depression or not was 86.3%, the sensitivity 79.5%, and the specificity 93.3%. And the accuracy of classification model the degree of elderly depression was 86.1%, sensitivity 93.9% and specificity 74.7%. Conclusions: In this study, the important variables of the estimated predictive model were identified using the random forest technique and the study was conducted with a focus on the predictive performance itself. Although there are limitations in research, such as the lack of clear criteria for the classification of depression levels and the failure to reflect variables other than KLoSA data, it is expected that if additional variables are secured in the future and high-performance predictive models are estimated and utilized through various machine learning techniques, it will be able to consider ways to improve the quality of life of senior citizens through early detection of depression and thus help them make public policy decisions.

• Food Science and Preservation
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• v.23 no.3
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• pp.291-300
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• 2016

Kiwifruit (Actinidia chinensis, Hayward) was stored at $25^{\circ}C$ for 0~30 days and investigated to find out the optimum storage time to obtain the best physical and functional properties for consumers' preference. Kiwifruits was stored at different time period (0, 5, 10, 15, 20, and 30 days) for investigating their physiochemical quality, nutritional components, and functional characteristics. Kiwifruits stored for 20~30 days showed the best physiochemical quality such as higher total acidity and proper firmness. They were also more enriched with dietary fibers, free sugar, and organic acid, although no significant changes were observed in crude protein, crude fat, and moisture content. For functional properties, kiwifruits stored for 20 days showed significantly higher contents of total phenolics, flavonoids, and actinidin. In addition, it showed stronger antioxidant activity, whitening effect, and proteolytic activity when compared with other samples. SDS-PAGE analysis showed the presence of actinidin enzyme in kiwifruits. These results indicated that the kiwifruits stored for 15~20 days possessed excellent quality and high concentrations of nutritional and functional compounds, which could be best for both fresh consumption and product processing.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.2
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• pp.47-53
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• 2015

The effects of electroless nickel immersion gold (ENIG) and organic solderability preservative (OSP) surface finishes on the in-situ intermetallics reaction and the electromigration (EM) reliability of Sn-3.0Ag-0.5Cu (SAC305) solder bump were systematically investigated. After as-bonded, $(Cu,Ni)_6Sn_5$ intermetallic compound (IMC) was formed at the interface of the ENIG surface finish at solder top side, while at the OSP surface finish at solder bottom side,$ Cu_6Sn_5$ and $Cu_3Sn$ IMCs were formed. Mean time to failure on SAC305 solder bump at $130^{\circ}C$ with a current density of $5.0{\times}10^3A/cm^2$ was 78.7 hrs. EM open failure was observed at bottom OSP surface finish by fast consumption of Cu atoms when electrons flow from bottom Cu substrate to solder. In-situ scanning electron microscope analysis showed that IMC growth rate of ENIG surface finish was much lower than that of the OSP surface finish. Therefore, EM reliability of ENIG surface finish was higher than that of OSP surface finish due to its superior barrier stability to IMC reaction.

• Korean Journal of Ichthyology
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• v.30 no.1
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• pp.27-35
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• 2018

The activity period and feeding ecology of the Iksookimia yongdokensis were investigated to obtain baseline data for its ecological characteristics in the Chuksan Stream and Gokgang Stream, Gyeongsangbuk-do, Korea from 2015 to 2016. I. yongdokensis were active on cobble, pebble and sand bottom from March to November when the water temperature exceeded $10^{\circ}C$, but tended to overwinter in cobble and pebble during the winter months (December~February) when the water temperature was lower than $10^{\circ}C$. During the day from 9 am to 15 pm, individuals of I. yongdokensis were highly active with a high rate of food consumption. I. yongdokensis activley fed on the surface of stone, pebble and sand as a filter feeder. Their main food sources analyzed with an index of relative importance (IRI) include Chironomidae (54.7%), Branchiopoda (10.1%), Rotatoria (8.7%), Arcellidae (8.6%), Chlorophyceae (6.5%) and Bacillariophyceae (5.1%). Juveniles of I. yongdokensis (total length 20~39 mm) fed on small-sized preys such as Rotatoria, Branchiopoda and Arcellidae, but they exhibited a transition in their prey-size markedly dominated by large-sized preys such as Chironomidae and Ephemeroptera as they grow.

• Clean Technology
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• v.23 no.1
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• pp.73-79
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• 2017

Recently usage of biomass is increased in pulverized coal power plants for reduction of $CO_2$ emission. Many problems arise when thermal share of the biomass is increased, and milling of the biomasses is one of the most important problems due to their low grindability when existing coal pulverizer is used. Grindability of coal can be measured through the HGI (Hardgrove grindability index) equipment as a standard, but method of measuring biomass grindability has not been established yet. In this study, grinding experiment of coal and biomass was performed using a lab-scale ball mill. One type of coal (Adaro coal) and six biomasses (wood pellet (WP), empty fruit bunch (EFB), palm kernel shell (PKS), walnut shell (WS), torrefied wood chip (TBC) and torrefied wood pellet (TWP)) were used in the experiment. Particle size distributions of the fuels were measured after being milled in various pulverization times. Pulverization characteristics were evaluated by portion of particles under the diameter of $75{\mu}m$. As a result, about 70% of the TBC and TWP were observed to be pulverized to sizes of under $75{\mu}m$, which implies that they can be used as alternative biomass fuels without modification of the existing mill. Other biomass was observed to have low grindability compared with torrefied biomass. Power consumption of the mill for various fuels was measured as well, and the results show that lower power was consumed for torrefied biomasses. This result can be used for characterization of biomass as an alternative fuel for pulverized coal power plants.

• Journal of Environmental Health Sciences
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• v.46 no.2
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• pp.150-158
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• 2020

Objective: This study is designed to measure the concentration of DBPs (disinfection by-products) in pool water and in air and to estimate the carcinogenic potential through the evaluation of inhalation exposure. Methods: The subjects were six indoor swimming pools with many users in Gwangju. Samples of pool water and indoor air were taken every one month from August 2018 to August 2019 and analyzed for eight swimming pool standards. Three-liter air samples were collected and the VOCs were analyzed using GC/MS directly connected to thermal desorption. Results: pH was 6.8-7.5 and the concentration of free residual chlorine in pool water was 0.40-0.96 ?/ℓ. Physicochemical test items such as KMnO₄ consumption and heavy metal items such as Aluminum met existing pool hygiene standards. No VOC materials were detected except for the DBPs. The concentration of THMs in the pool water was 11.05-41.77 ㎍/L and the THMs mainly consist of Chloroform (63-97%) and BDCM (3-31%). The concentration of indoor air THMs is 13.24-32.48 ㎍/㎥ and consists of Chloroform. The results of carcinogenic assessment of chloroform in the indoor swimming pool via inhalation exposure were 2.0 to 6.4 times higher than the 'acceptable risk level' suggested by the US EPA. Conclusions: The concentration of THMs in the pool water is 11.05-41.77 ㎍/L, most of which is chloroform. In addition, the concentration of indoor air THMs is 13.24-32.48 ㎍/㎥. The result of carcinogenic assessment of chloroform was 2.0 to 6.4 times higher than the 'acceptable risk level' suggested by the US EPA.