• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.2839-2846
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• 2021

In this study, experiments of downward-facing flow boiling were conducted to investigate material effects on CHF. Experiments were conducted using aluminum, copper, and carbon steel. It was found that different materials had different CHFs. Aluminum has the biggest CHF while copper has the lowest CHF for each mass flux. After experiment, surface wettability increased and surface became rougher, which was probably due to the oxidation process during nucleate boiling. The CHF difference is likely to be related to the surface wettability, roughness and thermal effusivity, which influences the bubble behavior and in turn affects CHF. Further studies are needed to determine which factor is dominant.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.1
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• pp.50-57
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• 1986

The fabricatoin sequence of GaAs MIS type diode and its electrical characteristics are presented. Used wafers were undoped GaAS wafer adn Te-doped GaAs wafer. Au and AuGe/Ni was used as schottky contact metal and ohmic contact metal respectively. Oxide layer on GaAs surface was formed by water vapor saturated oxide growth technique and dry oxidation technique. In Te-doped GaAs wafer, cutin voltage of MIS type diode was enhanced about 3V comparing with non-oxide layer diode. From light I-V characteristics fill factor of MIS type Te-doped GaAs diode was about 64%, Voc(open circuit voltage) was 0.67V.

• Journal of Microbiology and Biotechnology
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• v.33 no.8
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• pp.992-997
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• 2023

Ferroptosis is a new kind of programmed cell death of which occurrence in microorganisms is not clearly verified. The elevated level of reactive oxygen species (ROS) influences cellular metabolisms through highly reactive hydroxyl radical formation under the iron-dependent Fenton reaction. Iron contributes to ROS production and acts as a cofactor for lipoxygenase to catalyze poly unsaturated fatty acid (PUFA) oxidation, exerting oxidative damage in cells. While ferroptosis is known to take place only in mammalian cells, recent studies discovered the possible ferroptosis-like death in few specific microorganisms. Capacity of integrating PUFA into intracellular membrane phospholipid has been considered as a key factor in bacterial or fungal ferroptosis-like death. Vibrio species in bacteria and Saccharomyces cerevisiae in fungi exhibited certain characteristics. Therefore, this review focus on introducing the occurrence of ferroptosis-like death in microorganisms and investigating the mode of action underlying the cells based on contribution of lipid peroxidation and iron-dependent reaction.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.39.1-39.1
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• 2009

NiTi alloy is widely used innumerous biomedical applications (orthodontics, cardiovascular, orthopaedics, etc.) for its distinctive thermomechanical and mechanical properties such as shape memory effect, super elasticity, low elastic modulus and high damping capacity. However, NiTi alloy is still a controversial biomaterial because of its high Ni content which can trigger the risk of allergy and adverse reactions when Ni ion releases into the human body. In order to improve the corrosion resistance of the TiNi alloy and suppress the release of Ni ions, many surface modification techniques have been employed in previous literature such as thermal oxidation, laser surface treatment, sol-gel method, anodic oxidation and electrochemical methods. In this paper, the NiTi was electrochemically etched in various electrolytes to modify surface. The microstructure, element distribution, phase composition and roughness of the surface were investigatedby scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry(EDS), X-ray diffractometry (XRD) and atomic force microscopy (AFM). Systematic controlling of nano and submicron surface features was achieved by altered density of hydro fluidic acid in etchant solution. Nanoscale surface topography, such as, pore density, pore width, pore height, surface roughness and surface tension were extensively analyzed as systematical variables.Importantly, bone forming cell, osteoblast adhesion was increased in high density of hydro fluidic treated surface structures, i.e., in greater nanoscale surface roughness and in high surface areas through increasing pore densities.All results delineate the importance of surface topography parameter (pores) inNiTi to increase the biocompatibility of NiTi in identical chemistry which is crucial factor for determining biomaterials.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.2
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• pp.85-92
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• 2000

The purpose of this study was to identify the controlling factors to construct tidal flat ecosystems having similar characteristics as natural ones. We transplanted the soil in a constructed tidal flat to a natural one and vice versa. Parameters monitored after these transplantations were silt content, organic matter, bacterial population and oxidation-reduction potential. Moreover, the relationship among silt content, organic matter and bacterial population was investigated by laboratory column experiment. The silt content, organic matter, bacterial population and vortical profile of oxidation-reduction potential in the soil transplanted from the constructed tidal flat to the natural one changed to similar values to those In the natural one. On the contrary, all the parameters for the soil transplanted from the natural tidal flat to the constructed one changed to similar values as those in the constructed one. The silt contents in these two transplanted soils were in proportion to the organic carbon contents and bacterial population. Similarly, the bacterial population in laboratory column experiment increased with the increase in silt and organic matter contents. It seemed to be important to select a place to enhance accumulative of silt and/or to maintain the silt content by hydrodynamic control of seawater in order to construct a tidal flat having similar characteristics as natural one.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.10
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• pp.2779-2785
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• 2009

Among the livestock, chickens are raised because of the merit ingested protein in low-priced cost of production and are primary livestock increased the consumption of meat. The factors of influencing condition, odor is the most important factor. Odor substances are ammonia, amines, hydrogen sulfide and mercaptan which come from night soil. Livestock are prevented from rearing by means of these odor substances. Though the henhouse is heated using hot air type heater in the winter season, it is ventilated for the control of odor because of the increase of odor concentration. In the present work, composite catalytic system combined the existing facilities(hot air type heater) with catalytic system was developed, it could controled odor and hazardous gas using the oxidation/reduction reaction without extra operating cost. Moreover, the purpose of this work is to develop the catalysts which are cost competitive and can maximize energy efficiency. The catalysts are noble metal(Pt-Rh) and composite transition metal(Mn) type.

• The Korea Journal of Herbology
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• v.31 no.1
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• pp.69-75
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• 2016

Objectives : The aim of this study is to investigate the various effects of individual or combined extract of GamiSaengmaeksan (GSS) on cell viability, anti-inflammatory and antioxidant activityMethods : In order to evaluate cytotoxicity, MTT assay was performed. We investigated the levels of proinflammatory cytokines such as tumor necrosis factor (TNF)-α and interleukin (IL)-6 and interleukin (IL)-1β, and nitric oxide(NO) in LPS-induced RAW 264.7 cells to check the effects on anti-inflammatory activity. The level of NO production in RAW 264.7 cells was measured by using Griess reagent. The levels of cytokines and ROS were measured by Luminex and Flow cytometry, respectively.Results : At concentration of 200 ㎍/㎖ GSS, cytotoxicity was observed in RAW 264.7 cells. However, at concentration less than 100 ㎍/㎖ of both combine and individual GSS, cytotoxicity was not observed in Raw 264.7 cells. However, the level of ROS in RAW 264.7 cells were decreased at both extract of 100 ㎍/㎖ GSS. Also, the level of NO in RAW 264.7 cells were decreased from extraction of concentration of 100 ug/ml in GSS and individual-extraction of Liriopis Tuber, White Ginseng and Glycyrrhizae Radix. In addition, productions of pro-inflammatory cytokines (TNF-α) in LPS-induced RAW 264.7 cells were decreased from extraction of concentration of 10 and 100 (㎍/㎖) in GSS and individual-extraction of Liriopis Tuber.Conclusions : It is concluded that combined extract of GSS appears to be more effective in anti-oxidation and anti-inflammatory effect than those in individual-extraction of GSS. These results may be developed as a raw material for new therapeutics to ease the symptoms related with inflammatory and oxidative stress.

• Nuclear Engineering and Technology
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• v.52 no.3
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• pp.508-519
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• 2020

During transients or accidents, the reactor core is uncovered, and droplets entrained above the quench front collides with the uncovered fuel rod surface. Droplet impact cooling can reduce the peak cladding temperature. Besides zirconium-based cladding, versatile accidental tolerant fuel (ATF) claddings, including FeCrAl, have been proposed to increase the accident coping time. In order to investigate the effect of surface properties on droplet impact cooling of cladding surfaces, the droplet impact phenomena are photographed on the FeCrAl and zircaloy-4 (Zr-4) surfaces under different conditions. On the oxidized FeCrAl surface, the Leidenfrost phenomenon is not observed even when the surface temperature is as high as 550 ℃ with We > 30. Comparison of the impact behaviors observed on different materials shows that nucleate and transition boiling is more intensive on surfaces with larger thermal conductivity. The Leidenfrost point temperature (LPT) decreases with the solid thermal effusivity (${\sqrt{k{\rho}C_p}}$). However, the CHF temperature is relatively insensitive to the surface oxidation and Weber number. Droplet spreading diameter is analyzed quantitatively in the film boiling stage. Based on the energy balance a correlation is proposed for droplet maximum spreading factor. A mechanistic model is also developed for the LPT based on homogeneous nucleation theory.

• The Journal of Internal Korean Medicine
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• v.37 no.3
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• pp.467-483
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• 2016

Objective: This study was performed to investigate the effect of IUS (Inulsan, an extract of Artemisiae capillaris (茵蔯), Curcumae longae (鬱金), and Crataegi fructus (山査)) on anti-hyperlipidemia, anti-oxidation, and anti-inflammation.Method: We administered water extracts of Artemisiae capillaris, Curcumae longae, and Crataegi fructus for three weeks to db/db mice (C57BL/Ks), animal models induced with type 2 diabetes mellitus. Mice were divided into three groups: normal (C57BL/6J mice group), control group (db/db mice without administration of IUS) and IUS group (db/db mice treated with IUS). Then we measured total cholesterol, LDL cholesterol, HDL cholesterol, and triglyceride in the serum after the oral administration of IUS.Results: 1. IUS did not show any cytotoxicity in RAW 264.7 cells. 2. IUS decreased AST, ALP, and creatinine levelsand did not show any liver or renal toxicity in the db/db mice. 3. IUS increased DPPH and ABTS radical scavenging activity and decreased ROS production in RAW 264.7 cells. 4. IUS significantly decreased IL-1β, IL-6, and TNF-α production in RAW 264.7 cells. 5. IUS increased HDL cholesterol and significantly decreased total cholesterol and triglyceride in db/db mice. 6. IUS significantly decreased the atherogenic index and cardiac risk factor. 7. In contrast with the control group, fat infiltration in the liver and aorta decreased in IUS treated mice. The cell nucleus was located in the central area in H&E staining of liver. And endomembranes also were more thinner than the control group in H&E staining of aorta.Conclusions: These results suggest that IUS might be effective in the prevention and treatment of dyslipidemia.

• Journal of Acupuncture Research
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• v.32 no.3
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• pp.117-126
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• 2015

Objectives : This study was an analysis of the anti-inflammatory, anti-oxidative and skin whitening properties of Gamioncheong-decoctione(GMOCD) extract. Methods : GMOCD(96 g) and 2 L of distilled water were heated at $100^{\circ}C$ for four hours and then concentrated, frozen, freeze-dried, dissolved in distilled water and filtered. The following analysis was completed: cell cytotoxic effect using MTT assay, oxidative products of NO by griess assay, concentration of prostaglandin $E_2(PGE_2)$ by commercially competitive enzyme immunoassay, and cytokines($IL-1{\beta}$, IL-6 and TNF-${\alpha}$) by Bio-Plex$^{(R)}$ Suspension Array System's Bio-Plex Pro$^{TM}$ mouse cytokine, chemokine, and growth factor assay. Anti-oxidative effect was measured using the DPPH method and skin whitening effect using tyrosinase inhibition assay. Results : GMOCD water-extract did not show any toxicity at all doses and cell viability was more than 90 % at all doses. GMOCD water-extract significantly inhibited NO production at doses of 100, 200, $400{\mu}g/ml$, significantly inhibited $PGE_2$ production at doses of 200 and $400{\mu}g/ml$ and reduced the LPS-induced IL-$1{\beta}$, IL-6 and TNF-${\alpha}$ production in a dose-dependent manner. $IL-1{\beta}$ production was significantly reduced at a dose of $400{\mu}g/ml$ and IL-6 production was significantly reduced at doses of 200 and $400{\mu}g/ml$. DPPH free radical scavenging capability had a skin whitening effect rate of more than 50%. Tyrosinase inhibition activity was apparent in a dose-dependent manner. Conclusions : This study suggests that GMOCD water-extract suppressed NO and $PGE_2$ production and inhibited cytokines($IL-1{\beta}$, IL-6 and TNF-${\alpha}$). GMOCD also improved DPPH free radical scavenging capability. GMOCD water-extract increased tyrosinase inhibitory activity in a dose-dependent manner but this was not a statistically significant result.