• Journal of Digital Convergence
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• v.20 no.3
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• pp.507-516
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• 2022

The purpose of this study was to examine the factors influencing on the smartphone usage time according to the happiness perceived by adolescents. This study underwent the approval procedure for using the raw data of the 13th (2017) Adolescents' Health Behavior Online Survey through the homepage of Korea Centers for Disease Control and Prevention and selected 54,603 persons of 12-18 age groups as subjects of the study. The analysis was performed after generating a complex sample plan file by assigning weights using the IBM SPSS 23.0 program. There were significant differences in general characteristics and physical & psychological characteristics according to the use of the smartphone in the happy group and the unhappy group (p<.05). And there was a statistically significant difference in factors affecting smartphone usage time between the group of adolescents who perceived as happy and the group who perceived themselves as unhappy. It is necessary to improve the quality of life by increasing the level of happiness through the correct use of smartphones among adolescents.

• Resources Recycling
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• v.15 no.1 s.69
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• pp.37-45
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• 2006

For treating a huge amount of plastic waste with the environment problem, pyrolysis of plastic waste into alternative fuel oil is one or important issue in recycling methods. This study was introduced over the trend or generation of plastic waste, in Korea pyrolysis technology in domestic and foreign countries, basic technology in pyrolysis process and new technology of pyrolysis developed in KIER (Korea Institute of Energy research). The characteristics of process developed in KIER are the continuous loading treatment or mixed plastic waste with an automatic control system, the minimization of wax production by circulation pyrolysis system in non-catalytic reactor, the reuse of gas produced and the oil recovery from sludge generated in pyrolysis plant, which have greatly the advantage economically and environmetally. The experiment result data in 300 ton/yr pilot plant showed about $81\;wt\%$ liquid yield for 3 days continuous reaction time, and also the boiling point distribution of light oil (LO) and heavy oil (HO) produced in distillation tower was a little higher than that of commercial gasoline and diesel, respectively.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.10a
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• pp.34-46
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• 2005

For treating a huge amount of plastic waste with the environment problem, pyrolysis of plastic waste into alternative fuel oil is one of important issue in recycling methods. This study was introduced over the trend of generation of plastic waste, pyrolysis technology in domestic and foreign countries, basic technology in pyrolysis process and new technology of pyrolysis developed in KIER (Korea Institute of Energy Research). The characteristics of process developed in KIER are the continuous loading treatment of mixed plastic waste with an automatic control system, the minimization of wax production by circulation pyrolysis system in non-catalytic reactor, the reuse of gas produced and the oil recovery from sludge generated in pyrolysis plant, which have greatly the advantage economically and environmetally. The experiment result data in 300 ton/yr pilot plant showed about 81 wt% liquid yield for 3 days continuous reaction time, and also the boiling point distribution of light oil (LO) and heavy oil (HO) produced in distillation tower was a little higher than that of commercial gasoline and diesel, respectively.

• Journal of Animal Science and Technology
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• v.44 no.5
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• pp.541-548
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• 2002

This study, consisting of two experiments, was conducted to determine the effects of feeding heat treated protein and mineral complex (HPM) on milk production and composition, and ruminal fermentation of Holstein dairy cows. In in vitro experiment, HPM levels were 0, 0.2, 1 and 2%, and Timothy hay, which was substrate, was milled as 1 mm size, and the effects of HPM on pH, ammonia and VFA were analyzed after incubation times of 0, 6, 12, 24 and 48 h, respectively. The pH and ammonia production were not significantly different between treatments during the incubation. In addition, generally, total VFA and individual VFA were not affected by HPM on 0, 6 and 24 h. While, total VFA and individual VFA were increased in 0.2% and 1% of HPM supplemented treatments, but decreased in 2% of HPM treatment compared with control on 12 h. On 48 h, total VFA and individual VFA were increased in HPM treatments compared to control (P<0.05). However, A/P ratio was not affected by HPM supplementation. Gas production was higher in HPM treatment compared to control on 24 h (P<0.05) and 48 h (P<0.05). In lactating experiment, fourteen lactating Holstein cows were used for 4 months in a cross over experimental design. There were two treatments; no added HPM as a control and 0.2% of HPM added as a test treatment. Daily milk yield (P<0.001), 4% FCM (P<0.001), milk protein (P<0.05) and SNF (solid not fat; P<0.05) were increased in HPM treatment compared to control. While, milk fat, MUN (milk urea nitrogen) and SCC (somatic cell count) were not significantly different between treatments.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.32-39
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• 2000

The purpose of this study was to assess the cariogenic potential of five infant formulas in vitro. as compared with 10% sucrose solution and whole bovine milk. Buffering capacities were determined by the amount of 0.1 N lactic acid consumed to titrate the 50ml specimen solutions to pH 4.0. The pH of the specimen solution inoculated by Streptococcus mutans was measured by pH meter and the surface microhardness of primary tooth enamel immersed in the specimen solution was measured by the microhardness tester, before and after 48 hours incubation. Also, the solubility of calcium from synthetic hydroxyapatite was evaluated by atomic absorption spectrophotometer The buffering capacity of infant formulas was higher than that of sucrose solution and lower than that of milk, and there were significant differences among infant formulas(P<0.01). The average pH of infant formulas after 48 hours incubation was lower than that of sucrose solution and milk, and there was significant difference between infant formulas and milk(P<0.05). There were no signifiant differences among oops in the microhardness change of primary tooth enamel and in the amount of dissolved calcium ion from synthetic hydroxyapatite after incubation with Streptococcus mutans. In conclusion, infant formulas seemed to fulfill the basic requirments to cause dental caries in primary teeth, and there were significant differences of cariogenic potential among infant formulas. Cooperative efforts of dentistry and manufacturers to reduce the cariogenic potential of infant formulas would be necessary to prevent the early childhood caries in children.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.128-134
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• 2001

Male Sprague-Dawley rats received either a cholesterol diet(Control group) or cholesterol diets supplemented with the water-soluble extract of stem bark from Morus alba(M group) or Cudrania tricuspidata(C group) at the level of 1% for 2 weeks. Concentrations of total cholesterol and phospholipid in serum of C group and triglyceride in serum of M group were lower than those of control group. Concentration of cholesterol in liver of M and C groups has a tendency to be lower than that of control group. Antioxidative activities of water-soluble extracts from stem bark of Morus alba and Cudrania tricuspidata on the peroxidation of lipid in tissues of rats were also studied in vivo by measuring the formation of thiobarbituric acid reactive substances (TBARS). Concentration of TBARS in kidney of M and C groups was significantly lower than control group. However, concentration of TBARS in liver and brain of C and M groups was significantly higher than in control group. The result that concentration of nonheme ion was significantly increased in liver of the mulberry supplemented groups comparision to control group, suggested that enhanced concentration of nonheme ion was associated with enhanced peroxidation of lipid in this group. Concentration of TBARS in microsomes of liver and brain in control group induced with $Fe^{2+}$/ascorbate increased by reaction time at $37^{\circ}C$, whereas this observation in liver did not occurred in C and M groups. This study suggested that water-extract from stem bark of Morus alba and Cudrania tricuspidata exert hypotriglycerolemic effect as well as antioxidative effect in kidney and liver microsomes in rats fed a cholesterol diet.

• Clinical and Experimental Pediatrics
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• v.48 no.8
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• pp.881-885
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• 2005

Purpose : Airway dehydration and subsequent hyperosmolarity of periciliary fluid are considered critical events in exercise-induced bronchoconstriction. The aim of this study was to establish if a hyperosmolar challenge could induce activation of eosinophils. Methods : Human eosinophilic leukaemic cell lines, EoL-1 cells were incubated with hyperosmolar solutions for 15 minutes. Activation of EoL-1 cells was monitored by degranulation and superoxide anion production. In addition, we examined surface expression of CD69 and ICAM-1. Results : Hyperosmolar stimuli didn't induce superoxide anion production and degranulation. In addition, EoL-1 cells cultured with hyperosmolar medium at 930 mOsm/kg $H_2O$ resulted in no significant increment in fluorescent intensity of CD69 and ICAM-1 expression compared with results for cells incubated with isomolar medium. Conclusion : We found that hyperosmolar stimuli don't cause activation of EoL-1 cells, but further studies are required to determine the role of eosinophil in the mechanism of exercise-induced asthma.

• Journal of the East Asian Society of Dietary Life
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• v.25 no.4
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• pp.660-666
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• 2015

Natural food colorant are widely used to satisfy consumer preferences. Anthocyanins are red, blue and purple natural pigments. Purple-fleshed sweet potato (PSP) contains large quantities of anthocyanins. The aims of this work were i) to investigate the influence of sugars on the purple color of PSP jam and ii) to optimize the ratio of ingredients for sensory characteristics of PSP jam. Korean PSP variety "Sinjami" was used for the preparation of jam. The jams were prepared with various sugar contents (0, 20, 30, 40 and 50% total weight) consisting of steamed purple-fleshed sweet potato, water, lemon juice and apple juice. With increasing sugar contents, lightness (L) and redness (a) of PSP jams decreased while yellowness (b) increased, indicating that anthocyanins were degraded and/or brown pigments were formed due to high sugar content under heat treatment. Hardness, springiness, chewiness and cohesiveness showed significant differences among PSP jams with various sugar contents. In sensory evaluation, addition of sugar significantly increased scores for color and texture as compared to control samples. The color, texture and preference results indicate an optimal sugar content of 40% total ingredient weight for PSP jam.

• Restorative Dentistry and Endodontics
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• v.35 no.2
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• pp.96-105
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• 2010

The purpose of this study is to observe and compare the remineralization tendencies of artificial enamel caries lesion by remineralization solutions of different degree of saturations at pH 5.5, using a polarizing microscope and computer programs (Photoshop, Image pro plus, Scion Image, Excel). For this study, 48 sound permanent teeth with no signs of demineralization, cracks, or dental restorations were used. The specimens were immersed in lactic acid demineralization solution for 2 days in order to produce artificial dental caries that consist of surface and subsurface lesions. Each of 9 or 10 specimens was immersed in pH 5.5 lactic acid buffering remineralization solution of four different degrees of saturation (0.507, 0.394, 0.301, and 0.251) for 12 days. After the demineralization and remineralization, images were taken by a polarizing microscope (${\times}100$). The results were obtained by observing images of the specimens, and using computer programs, the density of caries lesions were est mated. While the group with the lowest degree of saturation (0.251) showed total remineralization feature from the surface to the subsurface of the lesion, the group with the highest degree of saturation (0.507) showed demineralization mainly on the surface of the lesion at the constant organic acid concentration 0.01 M and pH 5.5.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.12
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• pp.1675-1679
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• 2011

To improve the quality and palatability of Kochujang, the physicochemical properties, antioxidant capacity, and sensory evaluation of Kochujang were assessed when red ginseng and wild herbal extract were added during fermentation. This study investigated the antioxidant capacities of general Kochujang (GK) and Kochujang prepared with red ginseng and fermented wild herbal extract (RGK) by employing various in vitro antioxidant assays such as DPPH and FRAP assays. Inhibition of lioxygenase (LOX) activity was also investigated. RGK exhibited significant antioxidant effects compared to control in DPPH, FRAP, and LOX assays. The LOX inhibitory activity of RGK ($68.68{\pm}3.37%$) at 100 ${\mu}g$/mL was markedly higher than those of GK ($31.21{\pm}2.64%$) and NDGA (positive control, $30.54{\pm}1.36%$). All concentrations of RGK showed significantly higher FRAP activities than that of GK. The addition of red ginseng and fermented wild herbal extract exhibited better sensory characteristics in terms of color, flavor, taste and overall preference. We concluded that RGK improves not only functional properties but also sensory properties as well.