• Korean Journal of Materials Research
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• v.7 no.10
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• pp.898-907
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• 1997

Fe-22Cr-5AI-X(X=Zr, Y)합금을 1143K, 고온 황화(P$s_{2}$=1.11x$10^{-7}$atm, P$O_{s}$ =3.11x$10^{-20atm}$) 및 황화/산화 (P$s_{2}$=8.31x$10^{-8}$atm, P$O_{s}$ =3.31x$10^{-18atm}$) 환경의 복합가스 분위기에서 1-30시간동안 노출하여 합금표면에 형성된 부식층을 관찰하여 SEM/EDS로 분석하였다. Fe-22Cr-5AI합금은 고온 부식환경에서 부식 생성물의 성장은 포물선법칙을 따르고 주요 성분은 결함이 많고 다공질인 철과 크롬의 황화물[(Fe, Cr)Sx]이므로 고온 내식성이 감소하였다. Zr을 1wt%첨가한 Fe-22Cr-5AI합금의 고온 부식거동은 Y을 1wt%첨가한 합금과 비슷한 거동을 나타내었다. 황화환경에서는 Cr의 선택 황화에 의한 크롬 황화물(CrS)이 생성되고 노출시간의 경과에 따라 (Fe, Cr)Sx나 (Cr, Fe)Sx 등의 황화물의 성장으로 고온 내식성이 감소하였다. 그러나 황화/산화환경에서는 초기에는 알루미늄산화물(A $I_{2}$ $O_{3}$)및 지르코늄산화물(Zr $O_{2}$)등이 생성되어 보호적이었으나 15시간이후 부터 (Fe, Cr)Sx나 (Cr, Fe)Sx 의 황화물의 성장으로 고온 내식성이 감소하였다.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.5
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• pp.1019-1024
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• 2009

Diabetic neuropathy is characterized by the decrease of cell viability in neuron, which is induced by the hyperglycemia. HT22 cell is the neuron cell line originated from hippocampus. Ginsenosides have been reported to retain anti-diabetic effect. However, the preventive effect of ginsenosides in the condition of diabetic neuropathy was not elucidated. Thus, this study was conducted to examine the protective effect of ginsenoside total saponin (GTS), panoxadiol (PD), and panoxatriol (PT) in the high glucose-induced cell death of HT22 cells, an in vitro cellular model for diabetic neuropathy. In present study, high glucose increased lactate dehydrogenase(LDH) activity, the lipid peroxide(LPO) formation and induced the decrease of cell viability. These effects were completely prevented by the treatment of GTS, but partially prevented by the treatment of PD and PT. High glucose also increased the expression of Bax and cleaved form of caspase-3 but decreased that of Bcl-2. These effects of high glucose on Bax, Bcl-2 and cleaved form of caspase-3 were completely prevented by the treatment of GTS, but partially prevented by the treatment of PD and PT in HT22 cells. In conclusion, ginsenosides prevented high glucose-induced cell death of hippocampal neuron through the inhibition of oxidative stress and apoptosis in HT 22 cells.

• Journal of Microbiology and Biotechnology
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• v.25 no.4
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• pp.479-491
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• 2015

Lactobacillus species have been shown to enhance intestinal epithelial barrier function, modulate host immune responses, and suppress the growth of pathogenic bacteria, yeasts, molds, and viruses. Thus, lactobacilli have been used as probiotics for treating various diseases, including intestinal disorders, and as biological preservatives in the food and agricultural industries. However, the molecular mechanisms used by lactobacilli to suppress pathogenic bacterial infections have been poorly characterized. We previously isolated Lactobacillus plantarum JSA22 from buckwheat sokseongjang, a traditional Korean fermented soybean food, which possessed high enzymatic, fibrinolytic, and broad-spectrum antimicrobial activity against foodborne pathogens. In this study, we investigated the effects of L. plantarum JSA22 on the growth of S. Typhimurium and S. Typhimurium-induced cytotoxicity by stimulating the host immune response in intestinal epithelial cells. The results showed that coincubation of S. Typhimurium and L. plantarum JSA22 with intestinal epithelial cells suppressed S. Typhimurium infection, S. Typhimurium-induced NF-κB activation, and IL-8 production, and lowered the phosphorylation of both Akt and p38. These data indicated that L. plantarum JSA22 has probiotic properties, and can inhibit S. Typhimurium infection of intestinal epithelial cells. Our findings can be used to develop therapeutic and prophylactic agents against pathogenic bacteria.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.20-25
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• 2011

This paper analyzed the application of Superconducting Fault Current Limiter (SFCL) on 22.9 [kV] bus tie in a power distribution system. Commonly, the parallel operations of power main transformers offer a lot of merits. However, when a fault occurs in the parallel operation of power main transformer, the fault currents might exceed the interruption capacity of existing protective devices. To resolve this problem, thus, the SFCL has been studied as the fascinating device. In case that, Particularly, the SFCL could be installed to parallel operation of various power main transformers in power distribution system of the Korea Electric Power Corporation (KEPCO) on 22.9 [kV] bus tie, the effect of the resistance of SFCL could reduce the increased fault currents and meet the interruption capacity of existing protective devices by them. Therefore, we analyzed the effect of application and proposed the proper impedance of the R-type SFCL on 22.9 [kV] bus tie in a power distribution system using PSCAD/EMTDC.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.28 no.4
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• pp.74-91
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• 2015

Background and Objective : Asthma is a chronic inflammatory disease at the mucosa and is associated with excess production of Th2 cytokine and eosinophil accumulation in lung.Gamchomahwang-tangextract(GME) is one of the well known prescription used in oriental medicine for treating asthma. This study was designed to compare the anti-asthmatic effect of GME according to the ratio of 2 compounds.Methods : To examine the effects of GME on asthma, mice were sensitized with 100 ㎍ of OVA and 1 ㎎ of aluminum potassium sulfate(Alum; Sigma) intraperitoneally on day 1 and 15. From day 22, mice were challenged on 3 consecutive days with 5% OVA. The anti-asthmatic effects of GME were evaluated by enhanced pause(Penh), bronchoalveolar lavage fluids (BALF), inflammatory cytokine production and genes expression, serum IgE production. and histological change in lung tissue. GMEⅠ consists of ES and GU in the proportion 2:1(300 ㎎/㎏ group), GMEⅡ consist of ES and GU in the proprtion 4:1(300 ㎎/㎏ group).Results : GMEⅠ,Ⅱ generally inhibited lung inflammation, inflammatory cells infiltration and cytokine production and gene expression such as IL-4, IL-5 and IL-13 in BALF and serum IgE level. GMEⅡ significantly reduced the cytokine production and gene expression such as IL-4, IL-5 and IL-13 in BALF and GMEⅠ decreased cytokine production of IL-4, IL-13 in BALF and gene expression of IL-4, IL-5 in Lung. GMEⅡ potently inhibited the development of Penh and also reduced the number of eosinophil during OVA-induced AHR(airway hyper-reactivity). Overall the results show that GMEⅡ has more effect on inhibiting production, gene expression of cytokine, serum IgE level and development of Penh than GMEⅠ. Consequently, GMEⅡ might be more effective than GMEⅠ at inhibiting allergic asthma on the OVA-induced mice model.Conclusion : These results indicate that GME has a deep inhibitory effects on airway inflammation and hyperresponsiveness in mice model of asthma and that suppression of IL-4, IL-5, IL-13 expression and decrease of IL-4, IL-5, IL-13 production in BALF might contribute this effect. Hence, the results indicate that GME might be useful herbal medicine of allergic asthma. As a result, GMEⅡ mght be superior to GMEⅠ in the aspect of anti-asthmatic effect on the OVA-induced mice model.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.426-428
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• 2005

Recently, There has been growing interest in new renewable energy systems with high-energy efficiency due to the increasing energy consumption and environmental pollution problems, but an insertion of new renewable energy systems to existing power distribution systems can cause several problems such as voltage variations, harmonics, protective coordination, increasing fault current etc, because of reverse power. This paper was applied to Sukumar M, Brahma, A. Girgis[1] proposal schemes and identilys the faulted section performing short-circuit analysis by MATLAB programs to 22.9[kV] distribution system interconnected a large number of new renewable energy system and was analyzed on protective coordination between reclose and Sectionalizer.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.463-468
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• 1987

In this paper, a high impedance fault detection on 22.9kV multigrounded distribution system that has been very difficult by any existing conventional protective relaying systems is studied. Because the fault current is very low, it cannot be distinguished from neutral current caused by load unvalanced on multigrounded distribution system. We developed the new and best algorithms of high impedance ground fault detection. This algorithms are 'the even order power method, even order ratio method', 'and even order ratio varience method'. Using this algorithms, a detection device for high impedance faults is constructed and tested in the laboratory. And continually, it is installed and has been tested in KEPCO substations.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.1
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• pp.1-10
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• 2005

Screw compressor chillers are widely used in refrigeration for capacity over 30 RT. In general, chillers operate under part-load conditions during most of the time. Therefore, information on the characteristics of part-load is very important for better chiller performance and energy economy. In this study, performance tests of screw chiller with economizer using R22 and R407C under part-load conditions have been performed for various secondary fluid temperatures. Adoption of an economizer system increased the cooling capacity and improved COP except for lower part-load condition when economizer volume ratio is 1.01. For the same cooling capacity condition at part-load, COP's of both non-economizer and economizer system showed similar values.

• Journal of Korean Biological Nursing Science
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• v.22 no.4
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• pp.223-231
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• 2020

Purpose: The purpose of this study was to investigate the effects of taro extract on brain resilience in in vitro Parkinson's disease model induced by 6-hydroxydopamine (6-OHDA). Methods: To induce a neuroinflammatory reaction and the in vitro Parkinson's disease model, SH-SY5Y cells were stimulated with lipopolysaccharide (LPS) and 6-OHDA, respectively. After that, cells were treated with at various concentrations (1, 5, and 10 mg/mL) of taro extract. Then nitric oxide (NO) production, inducible nitric oxide synthase (iNOS), interleukin (IL)-6, synaptophysin (SYP) and growth associated protein (GAP)-43 messenger ribonucleic acid (mRNA) expression level were measured. Results: Taro extract significantly suppressed LPS-induced NO production. Meanwhile, iNOS and IL-6 mRNA expression decreased in a dose-dependent manner. In addition, taro increased the mRNA expression of SYP and GAP-43 mRNA. Conclusion: These findings indicate that taro played an important role in brain resilience by inhibiting neuronal cell death and promoting neurite outgrowth, synaptogenesis, and neural plasticity. The results of this study suggest that taro may contribute to the prevention of neurodegenerative disease and become a new and safe therapeutic strategy for Parkinson's disease.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.5
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• pp.651-660
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• 1998

In the LPCVD reactor the temperature variations within the wafer load are the most important factor to maintain the thickness of the materials deposited on the surface of the wafer constant and to affect the deformation of each wafer. In this study the temporal variations of radial and axial temperature nonuniformities of each wafer in the LPCVD reactor are numerically estimated by assuming diffuse reflection. To verify the validity of the present numerical results, the present results obtained from the transient analysis are compared with those of Badgwell's work in which a steady-state condition was assumed. The main objective of this work is to determine the temporal variations of the temperature of each wafer in the LPCVD process since the wafers experience severe change in temperature in the early stage of the process.