• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.651-657
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• 2020

Fluidization processes in which solid particles vividly move like gas or liquid have been widely used in various industrial sectors, such as thermochemical energy conversion and polymerization processes for general purpose polymer resins. One of the general purpose polymer resins, LLDPE(Linear low-density polyethylene) resins have been produced in bubbling fluidized bed processes in the world. In a bubbling fluidization polymerization reactors, LLDPE particles with relatively larger particle size and low density are fluidized by hydrogen gas for polymerization reaction. Though LLDPE polymerization reactors are one of bubbling fluidization processes, slugs that have negative impact for reaction exist or occur in these processes. Therefore, the fluidization state of LLDPE particles was investigated in a simulation model similar to a pilot-scale polymerization reactor (0.38 m l.D., 4.4 m High). In particular, the effect of gas velocity (0.45-1.2 m/s), solid density (900-199 kg/㎥), solid sphericity (0.5-1.0), and average particle size (120-1230 ㎛), on bed height and fluidization state were measured by using a CPFD(Computational particle-fluid dynamics) method. With CPFD analysis, the occurrence of a flat slug was visualized. Also, the change in particle properties, such as particle density, sphericity, and size, could reduce the occurrence of slug and bed expansion.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.400-411
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• 2017

This study aimed to maximize the effectiveness of motionbeat rhythm exercise on obese women and its applicability in all fields of sports. In addition, this study aimed to propose a plan to promote continuous exercise for people to incorporate as a means to improve healthy lifestyle. The results showed several effects of EEG on health promoting behaviors. Electroencephalogram (Alpha Power) of the left prefrontal cortex showed to have a significant effect on health promotion activities, with respect to stress management, in the motion beat rhythm exercise group. Considering all research findings, we found that the 8-week motion beat exercise can be used as an appropriate and effective social sport program for overweight women as it brings forth positive changes in the prefrontal cortex that maximizes the pleasantness of and interest in health promotion activities relating to stress management. Moreover, we suggest that it can be a method to create an environment for overweight people to continuously participate in exercises by providing results from fun and relaxingactivities, rather than just creating simple physical effects.

• Korean Journal of Microbiology
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• v.52 no.4
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• pp.421-427
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• 2016

Acne is known as the most common skin disease. It commonly occurs during adolescents, but it is also present in children and adults because of air pollution, drug abuse and so on. In addition to the hormonal, genetic and environmental factors, Propionibacterium acnes (P. acnes) have also critical roles in outbreak of acne by inducing inflammatory mediators. Increase of sebum production provides an ideal environment for P. acnes that induce inflammation on the skin by activation of monocytic cells and stimulation of inflammatory cytokines. In this study, natural extracts were investigated for anti-inflammatory effects against inflammatory acne by P. acnes infection in terms of reducing cytokine production. Eucalyptus globulus extracts effectively suppressed mRNA synthesis of inflammatory mediators such as $TNF-{\alpha}$, $IL-1{\beta}$, IL-2, and NLRP3 in P. acnes-activated macrophages. Moreover, Eucalyptus globulus extracts inhibit activation of transcription factors, $NF-{\kappa}B$ and NFAT, which are known as key regulators of inflammatory cytokine production. This study suggests the potential of using Eucalyptus globulus extracts as alternative agents for the treatment of acne.

• Food Science and Preservation
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• v.17 no.1
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• pp.123-130
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• 2010

We compared physiological activities in reflux extracts from Liriope platyphylla leaves and roots. The water extract of roots had the highest solid extraction yield of 53.96%. The greatest level of total polyphenols was 186.88 mg/g in methanol extracts from leaves, whereas water extract from leaves showed the highest concentration of flavonoid compounds, at 159.29 mg/g. The leaf extract had 97.42% of the electron-donating ability (EDA) of the positive control, at 0.5 mg/mL. The superoxide dismutase (SOD)-like activity of water extract of leaves was 9.75% of the positive control value, at 1.0 mg/mL. The nitrite scavenging ability of methanolic extract from leaves was highest, at 40.56% of the positive control level at pH 1.2 and a concentration of 1.0 mg/mL, whereas root extracts were ineffective in this regard. Inhibition of xanthine oxidase by leaf extracts was more than 99% of the positive control value at 1.0 mg/mL, whereas water and methanolic root extracts had activities of 93.75% and 68.47%, respectively. When tyrosinase inhibition was examined, the water extract of leaves had 22.80% of positive control activity but methanolic extracts were inactive. These results indicate that leaves of L. platyphylla will be more useful for development of functional products than the roots, which are used to make medicinal preparations.

• Food Science and Preservation
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• v.16 no.3
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• pp.412-418
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• 2009

We measured the levels of soluble protein, sugar, free amino acids, minerals, total polyphenols, and flavonoid compounds in Syneilesis palmata as part of a study on nutritional and functional materials for development of valuable foods. The content of soluble protein in the aerial and root portions were 210.36 mg% and 870.42 mg%, respectively. The amount of reducing sugar was 848.12 mg% (aerial parts) and 1,420.91 mg% (roots), and that of free sugar was 14.85 mg% in aerial parts and 355.00 mg% in roots. The free amino acid level in aerial parts was 1,613.10 mg% and that in roots was 3,282.96 mg%. The mineral content of aerial parts was 3,531.53 mg% and that of roots was 1,878.34 mg%. The K, Ca, and Mg levels were greater than those of other minerals, with K comprising more than 75% of the total mineral content. The levels of polyphenol and flavonoid compounds in aerial parts were 1,920.00 mg% and 843.95 mg%, respectively, and those in roots were 487.56 mg% and 91.07 mg%, respectively.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.11 no.1
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• pp.51-59
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• 2000

This study aims to reveal whether attachment relationship with parents can differ from children being accepted and rejected in peer relations, and whether children's rejection sensitivity can differ from children having secure and insecure attachment relationship with parents. Subjects were 218 students in fifth and sixth grade of primary school. Inventory of Parent and Peer Attachment(IPPA), Children's Rejection Sensitivity Questionnaire(CRSQ), and peer relation sociometrics were used as measurements. The results showed that children in secure attachment with parents had lower scores on the subscales of CRSQ, such as anxiety, anger, belief, and psychological reaction, than children in insure attachment relationship with parents. And IPPA scores were higher in children being accepted in peer relation than children being rejected. These results can be considered that early attachment relationship with parents may influence children's rejection sensitivity and peer relation.

• Journal of the Korean Magnetics Society
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• v.3 no.3
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• pp.201-207
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• 1993

Starting ingot of $Pr_{15}Fe_{77}B_{8}$ were prepared by vacuum induction melting under argon atmosphere. The ingot were induction melted in a quartz crucible and then ejected as a molten alloy throuth a 0.6 mrn orifice onto a rotating cop¬per wheel. An anisotropic magnet was prepared from ribbon by hot deformation techniques. A fully dense precursor magnet first made by pressing ribbons at $680^{\circ}C$ under a pressure of $21.8\;kg/mm^{2}$. A substantially oriented magnets were obtained by die-upset under various conditions. As the compression ratio increases, the $B_{r}$ value increases pronouncedly though $_{i}H_{c}$ decreases. Also, XRD analyses show increased diffraction peak from (006). From these results, it can be known that the magnetic easy axis was formed along the compression axis. As the die-upset speed increases, $_{i}H_{c}$ increases though $B_{r}$ decreases. The $B_{r}$ increases up to $750^{\circ}C$ of die-upset temperature and above this temperature decreases. The value of $4{\pi}M_{s}$ of the $Pr_{15}Fe_{77}B_{8}$ alloy prepared is found to be 11.8 KG. When the alloy was compressed by 0.8 under the die-upset speed of 0.05 m/sec at $750^{\circ}C$, $B_{r}$ was 11.0 KG indicating that the alloy has excellent magnetic anistropy. However, this alloy has some limitation because of low $_{i}H_{c}$.

• Journal of the Korean Magnetics Society
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• v.11 no.4
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• pp.141-145
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• 2001

The Mn$\_$80/Ir$\_$18.1/Pt$\_$1.9/ exchange bias layers (EBLs), which have a small amounts of Pt, exhibit a high value of H$\_$ex/. The Si/Ni-Fe/Mn$\_$80/Ir$\_$18.1/Pt$\_$1.9/ EBL shows the largest H$\_$ex/ of 187 Oe, which is equivalent to a exchange energy (J$\_$ex/) of 0.146 erg/cm$^2$. Mn$\_$80/Ir$\_$18.1/Pt$\_$1.9/ EBLS are estimated to have blocking temperature of about 250 $\^{C}$, which is higher than those of Mn-Ir EBLs and Mn-Ir-Pt EBLs with higher Pt contents. This result implies that a little addition of Pt element promotes thermal stability in the Mn-Ir-Pt EBLs. The chemical stability of Mn-Ir-Pt EBLs was characterized by potentiodynamic test, which was performed in 0.001 M NaCl solution. The current density of Mn-Ir-Pt films was gradually reduced with increasing Pt content. The present results indicate that the Mn-Ir-Pt with a small amount of Pt is suitable for an antiferromagnetic material for a reliable spin valve giant magnetoresistance device.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.4
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• pp.79-85
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• 2007

This study was focused on the feasibility of ultrasonic bonding of Au stud flip chip bumps on the flexible printed circuit board (FPCB) with three different surface finishes: organic solderability preservative (OSP), electroplated Au and electroless Ni/immersion Au (ENIG). The Au stud flip chip bumps were successfully bonded to the bonding pads of the FPCBs, irrespective of surface finish. The bonding time strongly affected the joint integrity. The shear force increased with increasing bonding time, but the 'bridge' problem between bumps occurred at a bonding time over 2 s. The optimum condition was the ultrasonic bonding on the OSP-finished FPCB for 0.5 s.

• Clean Technology
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• v.26 no.1
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• pp.65-71
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• 2020

Various solar hybrid energy conversion processes, which have both the advantages of renewable energy sources and fossil energy sources, have been developed in the world because stable and predictable energy supplies, such as electricity and natural gas, are necessary for modern societies. In particular, a solar hybrid energy conversion process based on a dual fluidized bed process concept has been expected as the promising solution for sustainable energy supply via thermochemical conversions, such as pyrolysis, combustion, gasification, and so on, because solar thermal energy could be captured and stored in fluidized bed materials. Therefore, the attrition and heat transfer characteristics of silicon carbide and alumina particles used for fluidized bed materials for the solar hybrid energy conversion process were studied in an ASTM D5757 reactor and a bubbling fluidized bed reactor with 0.14m diameter and 2m height. These characteristics of novel fluidized bed materials were compared with those of sand particles which have widely been used as a fluidized bed material in various commercial fluidized bed reactors. The attrition resistances of silicon carbide and alumina particles were higher than those of sand particles while the average values of heat transfer coefficient in the bubbling fluidized bed reactor were in the range of 125 ~ 152 W m^-2K^-1.