• Applied Science and Convergence Technology
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• v.26 no.5
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• pp.133-138
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• 2017

We investigated the interface defect engineering and reaction mechanism of reduced transition layer and nitride layer in the active plasma process on 4H-SiC by the plasma reaction with the rapid processing time at the room temperature. Through the combination of experiment and theoretical studies, we clearly observed that advanced active plasma process on 4H-SiC of oxidation and nitridation have improved electrical properties by the stable bond structure and decrease of the interfacial defects. In the plasma oxidation system, we showed that plasma oxide on SiC has enhanced electrical characteristics than the thermally oxidation and suppressed generation of the interface trap density. The decrease of the defect states in transition layer and stress induced leakage current (SILC) clearly showed that plasma process enhances quality of $SiO_2$ by the reduction of transition layer due to the controlled interstitial C atoms. And in another processes, the Plasma Nitridation (PN) system, we investigated the modification in bond structure in the nitride SiC surface by the rapid PN process. We observed that converted N reacted through spontaneous incorporation the SiC sub-surface, resulting in N atoms converted to C-site by the low bond energy. In particular, electrical properties exhibited that the generated trap states was suppressed with the nitrided layer. The results of active plasma oxidation and nitridation system suggest plasma processes on SiC of rapid and low temperature process, compare with the traditional gas annealing process with high temperature and long process time.

• Journal of KSNVE
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• v.5 no.2
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• pp.225-234
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• 1995

In this study, first, transformation process of damping ratios, whose are evaluated in active control analysis, into damping matrix resulting from installed viscous dampers is illustrated. Then, a method is followed to maximize the effect of response reduction, which leads to optimum locations and size of viscous dampers using sensitivity analysis. Highly coupled nonlinearity between damping ratios and dampers makes it hard to find the optimal size of dampers. Therefore, the nonlinearity is transformed to linear problem with small increments of damping ratios and the size of dampers can be found. However, there are many cases for the size of dampers satisfying the small increment of damping ratios, so it is necessary to select minimum size using optimization technique. To determine optimum locations of dampers, dampers are assumed to be installed between the different stories and their locations are selected corresponding corresponding to the degree of damping size. Numerical examples for the frame structure and the shear wall structure show that optimum locations and size of dampers are different form each other depending on the characteristics of modal responses of the structures. The proposed method in this study can be applied to get optimum locations of active controller in the active control.

• Journal of Sensor Science and Technology
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• v.30 no.6
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• pp.364-368
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• 2021

We developed a highly efficient organic photovoltaic (OPV) cell with a poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)]:[6,6]-phenyl-C71-butyric acid methyl ester active layer for harvesting lower-intensity indoor light energy to power various self-powered sensor systems that require power in the microwatt range. In order to achieve higher power conversion efficiency (PCE), we first optimized the thickness of the active layer of the OPV cell through optical simulations. Next, we fabricated an OPV cell with optimized active layer thickness. The device exhibited a PCE of 12.23%, open circuit voltage of 0.66 V, short-circuit current density of 97.7 ㎂/cm², and fill factor of 60.53%. Furthermore, the device showed a maximum power density of 45 ㎼/cm², which is suitable for powering a low-power (microwatt range) sensor system.

• Journal of the Korean Society of Food Culture
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• v.21 no.3
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• pp.344-350
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• 2006

The study aims to examine whether regular leisure activity of the elderly with active and passive types has a beneficial effect to enhance their health condition. The elderly subjects of 164 (82 of elderly who do active leisure and 82 of elderly who do passive leisure) aged over 60 years in Suwon area were employed. Survey questionnaires were administered to investigate general characteristics, life style, and health status along with anthropometric measurement. From the findings, the elderly who do active leisure were highly educated and better in living status. The elderly who do passive leisure showed higher drinking and smoking rates as well as higher obesity and overweight rates in comparison to the other counterpart. Furthermore, the elderly who do passive leisure were poor in health status. 'Painful knee and eye', 'lower back pain', and 'fatigue' were the most prevalent among subjective symptoms of the elderly. In conclusion, the elderly with active leisure activity seemed to have better life style and maintain good health status. Therefore, it is critically important to establish the health program combined with various leisure activity for the seniors to promote and energize the later years of life.

• Journal of Adhesion and Interface
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• v.25 no.1
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• pp.143-151
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• 2024

Organic photovoltaics (OPVs) have shown great potential as a new generation of energy harvesters because they possess many unique properties, including mechanical flexibility, lightweight, semi-transparency, and low-fabrication costs. Recent advancements in molecular structure and device engineering have led to achieving power conversion efficiency (PCE) exceeding 19%. However, these highly efficient active layer materials have been hampered in their commercialization by complex synthesis steps that result in high manufacturing costs. To address this issue, research is actively underway on low-cost active layer materials with simple structures. This paper introduces such cost-effective active layer materials and strategies for their synthesis.

• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.393-398
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• 2014

A highly efficient dual-mode linear CMOS stacked-FET power amplifier (PA) is implemented for 3G UMTS and 4G LTE handset applications. High efficiency is achieved at a backed-off output power ($P_{out}$) below 12 dBm by employing an active-bypass amplifier, which consumes very low quiescent current and has high load-impedance. The output paths between high- and low-power modes of the PA are effectively isolated by using a bypass switch, thus no RF performance degradation occurs at high-power mode operation. The fabricated 900 MHz CMOS PA using a silicon-on-insulator (SOI) CMOS process operates with an idle current of 5.5 mA and shows power-added efficiency (PAE) of 20.5%/43.5% at $P_{out}$ = 12.4 / 28.2 dBm while maintaining an adjacent channel leakage ratio (ACLR) better than -39 dBc, using the 3GPP uplink W-CDMA signal. The PA also exhibits PAE of 35.1% and $ACLR_{E-UTRA}$ of -33 dBc at $P_{out}$ = 26.5 dBm, using the 20 MHz bandwidth 16-QAM LTE signal.

• Osong Public Health and Research Perspectives
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• v.9 no.6
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• pp.289-298
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• 2018

Objectives: To describe the distribution of social factors, lifestyle habits and anthropometric measurements according to hypertension and Type-2 diabetes. Methods: A cross-sectional study was conducted in Gaza City, Palestine that included 379 patients (20-60 years) who had hypertension and/or diabetes. Three groups of patients were involved; 106 hypertensive (HT), 109 diabetic (T2DM) and 164 hypertensive diabetics (HT + T2DM). Results: The HT + T2DM group were older and had a higher body mass index compared to HT and T2DM groups. There were 62.3% patients who were female, 49.2% were highly educated HT patients, and 49.3% patients had a low level of education and were HT + T2DM. There were 55.8% patients who lived in large families. Patients who were passive smokers or never smoked before were mostly HT + T2DM, while active smokers and past smokers had T2DM. There were 48.2% patients who were highly physically active who had HT, 40.9% whom were moderately active had T2DM, and 53.8% of patients who had a low level of activity were HT + T2DM. Multivariate linear regression showed that having a diseased mother, living in a large family, being a past or passive smoker, or never having smoked, having a low or moderate level of activity, and having HT or HT + T2DM, were significantly associated with an increased body mass index. Conclusion: Parental health/disease conditions and environmental factors (social network and lifestyle habits) played the greatest role in the development of obesity and disease.

• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2442-2451
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• 2018

Novel highly active visible-light photocatalysts in the form of zinc bismuth oxide ($ZnBi_2O_4$) and graphite hybrid composites were prepared by coupling via a co-precipitation method followed by calcination at $450^{\circ}C$. The asprepared $ZnBi_2O_4$-graphite hybrid composites were tested for the degradation of rhodamine B (RhB) solutions under visible-light irradiation. The existence of strong electronic coupling between the two components within the $ZnBi_2O_4$-graphite heterostructure suppressed the photogenerated recombination of electrons and holes to a remarkable extent. The prepared composite exhibited excellent photocatalytic activity, leading to more than 93% of RhB degradation at an initial concentration of $50mg{\cdot}L^{-1}$ with 1.0 g catalyst per liter in 150 min. The excellent visible-light photocatalytic mineralization of $ZnBi_2O_4-1.0graphite$ in comparison with pristine $ZnBi_2O_4$ could be attributed to synergetic effects, charge transfer between $ZnBi_2O_4$ and graphite, and the separation efficiency of the photogenerated electrons and holes. The photo-induced $h^+$ and the superoxide anion were the major active species responsible for the photodegradation process. The results demonstrate the feasibility of $ZnBi_2O_4-1.0graphite$ as a potential heterogeneous photocatalyst for environmental remediation.

• Journal of Microbiology and Biotechnology
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• v.29 no.8
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• pp.1310-1315
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• 2019

Hyaluronidases enhance therapeutic drug transport by breaking down the hyaluronan barrier to lymphatic and capillary vessels, facilitating their tissue absorption. Commercially available hyaluronidases are bovine in origin; however, they pose risks such as bovine spongiform encephalopathy. The present study aimed to develop a novel, highly active hyaluronidase and assess its function. Therefore, in order to find the most efficient active hyaluronidase, we produced several shortened hyaluronidases with partial removal of the N- or C-terminal regions. Moreover, we created an enzyme that connected six histidines onto the end of the hyaluronidase C-terminus. This simplified subsequent purification using $Ni^{2+}$ affinity chromatography, making it feasible to industrialize this highly active recombinant hyaluronidase which exhibited catalytic activity equal to that of the commercial enzyme. Therefore, this simple and effective isolation method could increase the availability of recombinant hyaluronidase for research and clinical purposes.

• Journal of Families and Better Life
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• v.8 no.1
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• pp.69-82
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• 1990

The purposes of this are to figure out the amounts of leisure time of full-time homemakers and to find out leisure time factors contributed to raise the quality of life. The major findings are the followings: 1) Full-time homemakers spend 353 minutes(5.9 hours) on the average per day on the leisure. Time for active leisure(creative activities, sports activities, spectator events, going to the party, and so on) is 70 minutes, while that for passive leisure(watching TV. listening to the radio, reading newspapers. magazines. Books, chating, relaxing, card playing) is 283 minutes(4.7 hours). The passive leisure is the main type of spending leisure time. 2) The total leisure time of wives is significantly related to SES factors. The higher the wives age and education, the family income, and the age of the latest child, the more the wives total leisure time. But the more the family numbers, and the child numbers, the lower the leisure time. Active leisure time is highly rela ed to family income, while passive leisure time is considerably family composition. 3) The wives are mostly satisfied with their lives. The wives perceptions of the quality of life is related to wives's education, house type, and family income. 4) The wives total leisure time is not related to the quality of life. There is a positive correlation between active leisure time and the quality of life, while a negative relationship is between passive leisure time and the perception of the quality of life. 5) In analysis of causal model, it appears that family income and active leisure time of wives directly affect the perceived quality of life. The more the family income and active leisure time, the higher the quality of life. it is implicated for wives to take and active attitude and to reduce, if possible, passive leisure time and to increase active leisure time.