• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.6
• /
• pp.979-983
• /
• 2008

Planar antennas are very efficient for the use of the out-door data transmission applications due to their low-profile characteristics. But the size of the antenna in UHF band blocks the practical usage. In this paper, a miniaturized planar antenna is investigated for the application of AMR system in UHF band. The designed antenna is fabricated in the form of the microstrip patch on the FR-4 substrate. The miniaturization is achieved by slot-loading on the patch. First, effects of simple slots on the size reduction are analyzed, followed by the design using more complex slots resulting in the reduction ratio of 37.9% in 425.6 MHz and bandwidth of 3.8 MHz. The effort of epoxy coating for the protection is also investigated.

• Experimental and Molecular Medicine
• /
• v.51 no.2
• /
• pp.9.1-9.10
• /
• 2019

Mesangial cell proliferation has been identified as a major factor contributing to glomerulosclerosis, which is a typical symptom of diabetic nephropathy (DN). Lysophosphatidic acid (LPA) levels are increased in the glomerulus of the kidney in diabetic mice. LPA is a critical regulator that induces mesangial cell proliferation; however, its effect and molecular mechanisms remain unknown. The proportion of ${\alpha}-SMA^+/PCNA^+$ cells was increased in the kidney cortex of db/db mice compared with control mice. Treatment with LPA concomitantly increased the proliferation of mouse mesangial cells (SV40 MES13) and the expression of cyclin D1 and CDK4. On the other hand, the expression of $p27^{Kip1}$ was decreased. The expression of $Kr{\ddot{u}}ppel$-like factor 5 (KLF5) was upregulated in the kidney cortex of db/db mice and LPA-treated SV40 MES13 cells. RNAi-mediated silencing of KLF5 reversed these effects and inhibited the proliferation of LPA-treated cells. Mitogen-activated protein kinases (MAPKs) were activated, and the expression of early growth response 1 (Egr1) was subsequently increased in LPA-treated SV40 MES13 cells and the kidney cortex of db/db mice. Moreover, LPA significantly increased the activity of the Ras-related C3 botulinum toxin substrate (Rac1) GTPase in SV40 MES13 cells, and the dominant-negative form of Rac1 partially inhibited the phosphorylation of p38 and upregulation of Egr1 and KLF5 induced by LPA. LPA-induced hyperproliferation was attenuated by the inhibition of Rac1 activity. Based on these results, the Rac1/MAPK/KLF5 signaling pathway was one of the mechanisms by which LPA induced mesangial cell proliferation in DN models.

• Korean Journal of Metals and Materials
• /
• v.48 no.11
• /
• pp.1035-1040
• /
• 2010

The research efforts on GaN-based light-emitting diodes (LEDs) keep increasing due to their significant impact on the illumination industry. Surface mount technology (SMT) is widely used to mount the LED packages for practical application. In surface mount soldering both the device body and leads are intentionally heated by a reflow process. We studied on the effects of multiple reflows on microstructural variation and joint strength of the solder joints between the LED package and the substrate. In this study, Pb-free Sn-3.0Ag-0.5Cu solder and a finished pad with organic solderability preservatives (OSP) were employed. A $Cu_6Sn_5$ intermetallic compound (IMC) layer was formed during the multiple reflows, and the thickness of the IMC layerincreased with an increasing number of reflows. The shear force decreased after three reflows. From the observation of the fracture surface after a shear test, partially brittle fractures were observed after five reflows.

• Asian-Australasian Journal of Animal Sciences
• /
• v.32 no.12
• /
• pp.1864-1872
• /
• 2019

Objective: This study was conducted to evaluate the effects of Ecklonia stolonifera (E. stolonifera) extract addition on in vitro ruminal fermentation characteristics, methanogenesis and microbial populations. Methods: One cannulated Holstein cow ($450{\pm}30kg$) consuming timothy hay and a commercial concentrate (60:40, w/w) twice daily (09:00 and 17:00) at 2% of body weight with free access to water and mineral block were used as rumen fluid donors. In vitro fermentation experiment, with timothy hay as substrate, was conducted for up to 72 h, with E. stolonifera extract added to achieve final concentration 1%, 3%, and 5% on timothy hay basis. Results: Administration of E. stolonifera extract to a ruminant fluid-artificial saliva mixture in vitro increased the total gas production. Unexpectedly, E. stolonifera extracts appeared to increase both methane emissions and hydrogen production, which is contrasts with previous observations with brown algae extracts used under in vitro fermentation conditions. Interestingly, real-time polymerase chain reaction indicated that as compared with the untreated control the ciliate-associated methanogen and Fibrobacter succinogenes populations decreased, whereas the Ruminococcus flavefaciens population increased as a result of E. stolonifera extract supplementation. Conclusion: E. stolonifera showed no detrimental effect on rumen fermentation characteristics and microbial population. Through these results E. stolonifera has potential as a viable feed supplement to ruminants.

• The Journal of Internal Korean Medicine
• /
• v.42 no.5
• /
• pp.738-745
• /
• 2021

Objective: This study investigated the efficacy of using Nokyonggunbi-tang and other Korean medical treatments for a patient with consumptive disease and chronic fatigue. Methods: A 59-year-old female patient with fatigue, headache, dizziness, and neck pain due to consumptive disease and chronic fatigue was treated with herbal medicine (Nokyonggunbi-tang), together with acupuncture, pharmacopuncture, cupping, and chuna manual therapy, for 22 days. The treatment effects on the pain were evaluated using the scores for the Fatigue Severity Scale (FSS), European Quality of Life Five Dimensions (EQ-5d) Scale, Neck Disability Index (NDI), and Numerical Rating Scale (NRS). Results: Following treatment, the patient showed a decrease in the FSS, NDI, and NRS scores and an improvement in the EQ-5d score. Conclusions: Nokyonggunbi-tang and Korean medical treatment significantly improved fatigue symptoms in a patient with no substrate disease.

• Journal of Applied Biological Chemistry
• /
• v.64 no.3
• /
• pp.309-316
• /
• 2021

Kaempferol 3-O-galactoside (Trifolin), a member of the flavonol group, has been reported to have anticancer effects against promyelocytic leukemia, histocytic lymphoma, skin melanoma and lung cancer. Trifolin has been extracted and used from several plants, but the extraction process is complicated and the final yield is low. Biotransformation is an alternative tool to produce high value-added chemicals from inexpensive compounds. To synthesis trifolin from naringenin, three genes (PeFLS and OsUGE-PhUGT) were introduced into Escherichia coli, respectively. In order to synthesis trifolin from naringenin, a co-culture fermentation system was established by optimizing the cell concentration, biotransformation temperature and medium, isopropyl-β-D-thiogalactoside (IPTG) concentration, substrate supply concentration, and recombinant protein induction time. The established optimal conditions for trifolin production were a 3:1 ratio of BL-UGTE to BL-FLS, induction of recombinant protein at 25 ℃ for 4 h after addition of 2.0 mM IPTG, biotransformation at 30 ℃, and supply of 300 μM naringenin. Through the optimized co-culture fermentation system, trifolin was biosynthesized up to 67.3 mg/L.

• Food Engineering Progress
• /
• v.15 no.3
• /
• pp.214-220
• /
• 2011

$\beta$-Glucosidase enzyme reaction under high hydrostatic pressure was investigated in terms of physical chemistry. A model substrate (p-nitrophenyl-${\beta}$-D-glucopyranoside(pNPG)) was used, and the pressure effects on the enzymatic hydrolysis (pNPG${\rightarrow}$pNP) at 25 MPa, 50 MPa, 75 MPa, and 100 MPa were analyzed. Two parts of the reaction such as kinetic and equilibrium stages were considered for mathematical modelling, and their physicochemical parameters such as forward and inverse reaction constants, equilibrium constant, volume change by pressure, etc. were mathematically modeled. The product concentration increased with pressure, and the two stages of reaction were observed. Prediction models were derived to numerically compute the product concentrations according to reaction time over kinetic to equilibrium stages under high pressure condition. Conclusively, the $\beta$-Glucosidase enzyme reaction could be activated by pressurization within 100 MPa, and the developed models were very successful in their prediction.

• Korean Journal of Materials Research
• /
• v.29 no.7
• /
• pp.456-462
• /
• 2019

ZnO thin-films are grown on a p-Si(111) substrate by RF sputtering. The effects of growth temperature and $O_2$ mixture ratio on the ZnO films are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and room-temperature photoluminescence (PL) measurements. All the grown ZnO thin films show a strong preferred orientation along the c-axis, with an intense ultraviolet emission centered at 377 nm. However, when $O_2$ is mixed with the sputtering gas, the half width at half maximum (FWHM) of the XRD peak increases and the deep-level defect-related emission PL band becomes pronounced. In addition, an n-ZnO/p-Si heterojunction diode is fabricated by photolithographic processes and characterized using its current-voltage (I-V) characteristic curve and photoresponsivity. The fabricated n-ZnO/p-Si heterojunction diode exhibits typical rectifying I-V characteristics, with turn-on voltage of about 1.1 V and ideality factor of 1.7. The ratio of current density at ${\pm}3V$ of the reverse and forward bias voltage is about $5.8{\times}10^3$, which demonstrates the switching performance of the fabricated diode. The photoresponse of the diode under illumination of chopped with 40 Hz white light source shows fast response time and recovery time of 0.5 msec and 0.4 msec, respectively.

• Current Photovoltaic Research
• /
• v.6 no.4
• /
• pp.102-108
• /
• 2018

A glass-texturing technique was developed for photovoltaic (PV) module cover glass; periodic honeycomb textures were formed by using a conventional lithography technique and diluted hydrogen fluoride etching solutions. The etching conditions were optimized for three different types of textured structures. In contrast to a flat glass substrate, the textured glasses were structured with etched average surface angles of $31-57^{\circ}$, and large aspect ratios of 0.17-0.47; by using a finite difference time-domain simulation, we show that these textured surfaces increase the amount of scattered light and reduce reflectance on the glass surface. In addition, the optical transmittance of the textured glass was markedly improved by up to 95% for wavelengths ranging from 400 to 1100 nm. Furthermore, applying the textured structures to the cover glass of the PV module with heterojunction with intrinsic thin-layer crystalline silicon solar cells resulted in improvements in the short-circuit current density and module efficiency from 39 to $40.2mA/cm^2$ and from 21.65% to 22.41%, respectively. Considering these results, the proposed method has the potential to further strengthen the industrial and technical competitiveness of crystalline silicon solar cells.

• Journal of Ecology and Environment
• /
• v.42 no.4
• /
• pp.198-204
• /
• 2018

Background: The effective use of habitats is essential for the successful adaptation of a species to the local environment. Although habitats exhibit a hierarchical structure, including macro-, meso-, and microhabitats, the relationships among habitats of differing hierarchy have not been well studied. In this study, we studied the quantitative measures of microhabitat use of Gekko japonicus from three field populations in Japan: one at Tsushima Island, one at Nishi Park, Fukuoka, and one at Ohori Park, Fukuoka. We investigated whether land cover type, a higher hierarchical habitat component, was associated with quantitative microhabitat use, a lower hierarchical component, in these populations. Results: The substrate temperature where we located geckos (SubT) and the distance from the ground to the gecko (Height) were significantly different among the three populations. In particular, SubT on Tsushima Island was lower than it was in the other two populations. Irradiance at gecko location and Height were significantly different among the land cover types. In particular, Height in evergreen needleleaf forest was significantly lower than that in deciduous broadleaf forest. Furthermore, significant interactions between population and land cover type were observed for the SubT and Height variables. Conclusions: The quantitative measures of microhabitat use of G. japonicus varied with population and land cover type, which exhibited significant interaction effects on microhabitat use variables. These results suggest that higher hierarchical habitat components can affect the quantitative measures of lower hierarchical microhabitat use in nocturnal geckos.