• Journal of the Chungcheong Mathematical Society
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• v.33 no.1
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• pp.9-18
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• 2020

In this paper, we investigate the stability of a quadratic-cubic-quartic functional equation $$f(x+ky)+f(x-ky)-k^2f(x+y)-k^2f(x-y)-2(1-k^2)f(x)-{\frac{k^2(k^2-1)}{6}}(f(2y)+2f(-y)-6f(y))=0$$ by applying the direct method in the sense of Gǎvruta.

• Polymer(Korea)
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• v.38 no.1
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• pp.38-42
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• 2014

The poly[(9,9-bis((6'-(N,N,N-trimethylammonium)hexyl)-2,7-fluorene)-alt-(9,9-bis(2-(2-(2-methoxyethoxy)ethoxy)ethyl)-9-fluorene)) dibromide (WPF-6-oxy-F)] and graphene oxide (GO) was blended and irradiated with gamma ray under ambient condition. This WPF-6-oxy-F-GO composite was investigated as a hole-transporting layer (HTL) in organic solar cells (OSCs). Compared with the pristine GO, the sheet resistance ($R_{sheet}$) of irradiated WPF-6-oxy-F-GO was decreased about 2 orders of magnitude. The reason for the decrease of $R_{sheet}$ is the effect of efficient ${\pi}-{\pi}$ packing resulted from the formation of C-N bond between WPF6-oxy-F and GO. As a result, the efficiency of OSCs was dramatically enhanced ~ 6.10% by introducing irradiated WPF-6-oxy-F-GO as a HTL. WPF-6-oxy-F-GO is a sufficient candidate for HTL to facilitate the low-cost and high efficiency OSCs.

• The korean journal of orthodontics
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• v.27 no.4 s.63
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• pp.539-548
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• 1997

The purpose of this study was to evaluate the effectiveness of gargling solution with 0.05% NaF and 10% Xylitol in orthodontic patients with fixed appliance. The sample consisted of 20 patients who were classified into an experimental group and a control group, 10 patients each. Experimental group was used experimental gargling solution and the control group was used with placebo solution. The change of S. mutans was analysed by culture on MSB and BHI agar plate pre and post 3, 6, 9 weeks. The results were as follows. 1 There were significant reduction in the number of S. mutans C.F.U. between pre and post 3 weeks(p<0.01), 9 weeks(p<0.05) in experimental group 2. There were significant reduction in the ratio of S. mutans C.F.U. to total C.F.U. between pre and post 3, 6, 9 weeks(p<0.01) in experimental group. 3. S. mutans, which were reduced until 3 weeks, did not show significant change after 3, 6, 9 weeks. 4. S. mutans were strongly suppressed until 3 weeks after gargling solution with 0.05% NaF and 10% Xylitol.

• International Journal of Oral Biology
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• v.35 no.2
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• pp.51-60
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• 2010

Few studies have evaluated the apoptosis-inducing efficacy of NaF on cancer cells in vitro but there has been no previous investigation of the apoptotic effects of NaF on human oral squamous cell carcinoma cells. In this study, we have investigated the mechanisms underlying the apoptotic response to NaF treatment in the YD9 human squamous cell carcinoma cell line. The viability of YD9 cells and their growth inhibition were assessed by MTT and clonogenic assays, respectively. Hoechst staining, DNA electrophoresis and TUNEL staining were conducted to detect apoptosis. YD9 cells were treated with NaF, and western blotting, immunocytochemistry, confocal microscopy, FACScan flow cytometry, and MMP and proteasome activity assays were performed sequentially. The NaF treatment resulted in a time- and dose-dependent decrease in YD9 cell viability, a dose-dependent inhibition of cell growth, and the induction of apoptotic cell death. The apoptotic response of these cells was manifested by nuclear condensation, DNA fragmentation, the reduction of MMP and proteasome activity, a decreased DNA content, the release of cytochrome c into the cytosol, the translocation of AIF and DFF40 (CAD) into the nucleus, a significant shift of the Bax/Bcl-2 ratio, and the activation of caspase-9, caspase-3, PARP, Lamin A/C and DFF45 (ICAD). Furthermore, NaF treatment resulted in the downregulation of G1 cell cyclerelated proteins, and upregulation of p53 and the Cdk inhibitor $p27^{KIP1}$. Taken collectively, our present findings demonstrate that NaF strongly inhibits YD9 cell proliferation by modulating the expression of G1 cell cycle-related proteins and inducing apoptosis via mitochondrial and caspase pathways.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.3
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• pp.266-272
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• 2016

In this study, we analysed the technology convergence of Internet of Things(IoT) by International Patent Classification(IPC) code analysis. 163 patent applications in Korea are the subjects of this study. We confirmed that the most representative IPC code combinations between Main and Sub categories are G06Q 50/24-G06Q 50/22(6 cases), H04L 29/02-H04L 12/28(4 cases), G06F 15/16-G06F 3/048(3 cases), G06F 15/16-G06F 9/44(3 cases), and G06Q 50/22-G06Q 50/24(3 cases). The field of Health Care business have been prepared 9 patent applications by technology convergence between 'Health Care(G06Q 50/22)' and 'Patient Record Management(G06Q 50/24)'. Finally we also concluded that the core IPC code are G06F 15/16, G06Q 50/22, G06Q 50/24, and H04L 12/28 by the technology convergence interconnections analysis of IoT patent applications.

• Journal of Environmental Health Sciences
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• v.42 no.2
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• pp.112-117
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• 2016

Objectives: In this study, we investigated the biodegradation rates of 8 perfluorooctanesulfonate (PFOS) alternatives synthesized at the at Changwon National University in comparison to those of PFOS potassium salt and PFOS sodium salt. Methods: A biodegradability test was performed for 28 days with microorganisms cultured in the good laboratory practice laboratory at the Korea Environment Corporation following the OECD Guidelines for the testing of chemicals, Test No. 301 C Results: While $C_5H_8F_3SO_3K$, $C_8F_{17}SO_3K$ and $C_8F_{17}SO_3Na$ were not degraded after 28 days, the 3 alternatives were biodegraded at the rates of 31.4% for $C_8H_8F_9SO_3K$, 25.6% for $C_{10}H_8F_{13}SO_3K$, 23.6% for $C_{25}F_{17}H_{32}S_3O_{13}Na_3$, 20.9% for $C_{15}F_9H_{21}S_2O_8Na_2$, 15.5% for $C_{23}F_{18}H_{28}S_2O_8Na_2$, 8.5% for $C_{17}F_9H_{25}S_2O_8Na_2$ and 4.8% for $C_6H_8F_5SO_3K$. When the concentration was the same(500 mg/L), $C_{23}F_{18}H_{28}S_2O_8Na_2$ had the lowest tension with 20.94 mN/m, which was followed by $C_{15}F_9H_{21}S_2O_8Na_2$ (23.36 mN/m), $C_{17}F_9H_{25}S_2O_8Na_2$ (27.31 mN/m), $C_{25}F_{17}H_{32}S_3O_{13}Na_3$ (28.17 mN/m), $C_{10}H_8F_{13}SO_3K$ (29.77 mN/m) and $C_8H_8F_9SO_3K$ (33.89 mN/m). Having higher surface tension of 57.64 mN/m and 67.57 mN/m, respectively, than those of the two types of PFOS salts, $C_6H_8F_5SO_3K$ and $C_5H_8F_3SO_3K$ were found valueless as substitute for PFOS. Conclusion: The biodegradation test suggest that 6 compounds could be used as substitutes for PFOS. $C_{23}F_{18}H_{28}S_2O_8Na_2$ and $C_{15}F_9H_{21}S_2O_8Na_2$ were found to be the best substitutes based on biodegradation rate and surface tension, followed by $C_{25}F_{17}H_{32}S_3O_{13}Na_3$, $C_8H_8F_9SO_3K$ and $C_{10}H_8F_{13}SO_3K$. $C_{17}F_9H_{25}S_2O_8Na_2$ was found to have relatively low value as an alternative but it still had a potential to substitute the conventional PFOS.

• Journal of Sensor Science and Technology
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• v.3 no.2
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• pp.65-73
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• 1994

TO:F($SnO_{2}:F$) thin films were prepared by RF magnetron sputtering system. The dependence of their structural, electrical, and optical properties on deposition conditions such as substrate temperature, working pressure and power was studied. The optimum conditions of TO:F thin film are $SnF_{2}$ content of 15wt.% in target, RF power of 150W, substrate temperature of $150^{\circ}C$ and working pressure of 2mmTr. The resistivity and transmittance at 550nm in visible spectrum of the TO:F film deposited at optimum condition are $9{\times}10^{-4}{\Omega}{\cdot}cm$ and above 85%, respectively. For the films deposited from the target without $SnF_{2}$ and with 15wt.% $SnF_{2}$, the optical bandgaps calculated from the transmittance curves are 3.84 and 3.9eV, respectively. X-ray diffraction patterns showed that TO and TO:F films had tetragonal rutile structure with (101), (200) direction.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.1
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• pp.7-13
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• 2004

As a novel anti-wrinkle agent, 3,9-diferuloyl-6-oxopterocarpen (Tensolin-F$^{(R)}$) has been synthesized and its anti-aging effects have been investigated. In the present study, to investigate the relationship between aging and Tensolin-F$^{(R)}$, we examined its effect on scavenging activities of radicals and reactive oxygen species (ROS), in vitro inhibition activity of matrix-metalloproteinase (MMP) and expression of UVA-induced MMPs in human dermal fibroblasts (HDF). Tensolin-F$^{(R)}$ was found to show activities of scavenging radicals and ROS with the $IC_{50}$/ values of 0.2 mM and 0.95 mM against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and superoxide radicals, respectively, in the xanthine/xanthine oxidase system. Fluorometric assays for the proteolytic activities of MMP-l (collagenase) were performed using fluorescent collagen substrates. Tensolin-F$^{(R)}$ inhibited the activities of MMP-l in a dose-dependent manner and the $IC_{50}$/ values calculated from semi-log plots were 0.025 mM. Also, UVA induced MMP-1 expression was reduced 85％ by treatment with Tensolin-F$^{(R)}$ at 0.8 uM, which was reduced dose-dependent manner. The results of clinical study showed that 4.8 mM Tensolin-F$^{(R)}$ treated group reduced wrinkle significantly compared with placebo treated group (P 〈 0.05). Taken together, these result suggest that Tensolin-F$^{(R)}$ act as an anti-wrinkle agent by taking effects to antioxidation and reducing UVA-induced MMP-l production.-l production.

• Journal of Ginseng Research
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• v.21 no.3
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• pp.141-146
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• 1997

The role of cAMP in the differentiation process of F9 cells induced by ginsenosides was examined by performing transient transfixion assay with CRE-luciferase reporter plasmid, GR thansactivation assay with GRE-luciferase activity with or without treatment of CAMP and forskolin, an activator of adenylate cyclase, and protein klnase A assay in the presence of ginsenosides. Ginsenosides had no effect on CRE-transactivation activity, whereas retinoic acid induced the activity. When cAMP or forskolin was treated with ginsenosides, GRE-luciferase activity was further augumented by them. In addition, ginsenosides induced protein kinase A activity in the presence of cAMP. These results suggest that ginsenosides activate cAMP-dependent protein kinase A which, in turn, increase GR activity in F9 cells.

• Journal of Ginseng Research
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• v.21 no.3
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• pp.147-152
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• 1997

Ginsenosides $Rh_1$ and $Rh_2$ Induced the differentiation of F9 teratocarcinoma stem cells. These agents are structurally similar to the steroid hormones, therefore, we speculated that the steroid receptor (s) or novel nuclear receptor (s) could be involved in the differentiation process induces by them. Based on this speculation, we tried to alone new nuclear receptors with reverse transcription-polymerase chain reaction (RT-PCR) method by isolating RNA from F9 teratocarcinoma cells induced by ginsenosides. By using RT-PCR with degenerated primers from highly conserved DNA binding domain of nuclear receptors, we identified several nuclear receptors. In northern blot analysis we found that these clones are transcriptionally regulated by ginsenoside Rhl or Rh2 treatment. Further characterizations of these clones are needed to identify the mechanism of gene expression, which has an important role in the differentiation of F9 cells induced by ginsenosides.