• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.27 no.5
• /
• pp.572-582
• /
• 1994

To investigate water mass structure and DO(Dissolved Oxygen) distribution in Chinhae Bay, temperature, salinity and DO were observed in the bay in summer and winter from 1990 to 1993, and two-dimensional tidal current and parameter log($H/U^3$) were computed. Shallow water fronts in the bay were formed in summer in Kaduk channel and the central part of the bay having log($H/U^3$) values of $2.0{\sim}2.5$. Oxygen deficiency at the bottom layer in summer occurred in the western and northern part of the bay with weak tidal current, where the value of log($H/U^3$) was more than about 3.5 and $M_2$ tidal current was less than about 20 cm/s. DO concentration at the bottom layer of Kaduk channel and the central channel of the bay having the strong tidal current was more than about 3.5 mg/l. The isolines of DO concentration were nearly parallel to the isovelocity, and the concentrations correlated with the frontal location. The frontal location and DO distribution were influenced by tidal range, river inflow and meteorological conditions, and also correlated with bottom slope characteristics.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.256-256
• /
• 2012

Oxide semiconductors such as zinc tin oxide (ZTO) or indium gallium zinc oxide (IGZO) have attracted a lot of research interest owing to their high potential for application as thin film transistors (TFTs) [1,2]. However, the instability of oxide TFTs remains as an obstacle to overcome for practical applications to electronic devices. Several studies have reported that the electrical characteristics of ZnO-based transistors are very sensitive to oxygen, hydrogen, and water [3,4,5]. To improve the reliability issue for the amorphous InGaZnO (a-IGZO) thin-film transistor, back channel passivation layer is essential for the long term bias stability. In this study, we investigated the instability of amorphous indium-gallium-zinc-oxide (IGZO) thin film transistors (TFTs) by the back channel contaminations. The effect of back channel contaminations (humidity or oxygen) on oxide transistor is of importance because it might affect the transistor performance. To remove this environmental condition, we performed vacuum seasoning before the deposition of hybrid passivation layer and acquired improved stability. It was found that vacuum seasoning can remove the back channel contamination if a-IGZO film. Therefore, to achieve highly stable oxide TFTs we suggest that adsorbed chemical gas molecules have to be eliminated from the back-channel prior to forming the passivation layers.

• Journal of the Korea Safety Management & Science
• /
• v.20 no.4
• /
• pp.7-13
• /
• 2018

This study investigates the enhancement of the oxygen diffusion rate in the cathode channel of a proton exchange membrane fuel cell (PEMFC) by pure oscillating flow, which is the same as the mechanism of human breathe. Three-dimensional numerical simulation, which has the full model of the fuel cell including electrochemical reaction, ion and electronic conduction, mass transfer and thermal variation and so on, is performed to show the phenomena in the channel at the case of a steady state. This model could analysis the oscillating flow as a moving mesh calculation coupled with electrochemical reaction on the catalyst layer, however, it needs a lot of calculation time for each case. The two dimensional numerical simulation has carried on for the study of oscillating flow effect in the cathode channel of PEMFC in order to reduce the calculation time. This study shows the diffusion rate of the oxygen increased and the emission rate of the water vapor increased in the channel by oscillating flow without any forced flow.

• Transactions of the Korean hydrogen and new energy society
• /
• v.33 no.5
• /
• pp.550-556
• /
• 2022

In this study, the flow uniformity was analyzed by performing numerical analysis on the 1 kWe internal manifold type solid oxide fuel cell stack according to the channel height of the separator. Also, it was examined by varying the fuel utilization rate and oxygen utilization rate. From the calculation results, we found that as the channel height of the separator decreased, the pressure drop increased exponentially. In addition, it was found that as the channel height of the separator decreased, the gas flow resistance inside the unit cell increased, and the flow resistance increased the pressure drop, thereby improving the flow uniformity inside the stack. Finally, the calculation results showed that as the fuel and oxygen utilization increased, the flow uniformity also improved.

• Journal of Electrical Engineering and Technology
• /
• v.6 no.4
• /
• pp.539-542
• /
• 2011

Thin-film transistors (TFTs) are fabricated using an amorphous indium gallium zinc oxide (a-IGZO) channel layer by rf-magnetron sputtering. Oxygen partial pressure significantly changed the transfer characteristics of a-IGZO TFTs. Measurements performed on a-IGZO TFT show the change of threshold voltage in the transistor channel layer and electrical properties with varying $O_2$ ratios. The device performance is significantly affected by adjusting the $O_2$ ratio. This ratio is closely related with the modulation generation by reducing the localized trapping carriers and defect centers at the interface or in the channel layer.

• Journal of the Korean Institute of Navigation
• /
• v.8 no.1
• /
• pp.49-70
• /
• 1984

Spatial and temporal variations of hydrography and currents are investigated in the Southeastern Sea of Korea during October 1982. The distribution of the water mass of high salinity (>34.40${\textperthousand}$) and low dissolved oxygen concentration (<5.0ml/l) indicates that the Tsushima current flows northward as it passes the Western Channel of the Korea Strait. The cold water (<$6.0^{\circ}c$) with low salinity (<$34.20{\textperthousand}$) and high dissolved oxygen concentration (>6.0ml/l) reaches the bottom of the western channel of the Korea Strait after flowing southward leaning against the slope rather than following the deepest part of the Channel. Repeated sections in the Korea Strait show a remarkable change of hydrographic structure over a period of 4 days ; both warn and cold waters are intensified, particularly in the eastern part of the strait toward the Tsushima Island.

• Journal of the Korean Electrochemical Society
• /
• v.9 no.4
• /
• pp.170-177
• /
• 2006

Optimum design of flow channel in the separation plate of Proton Exchange Membrane Fuel Cell is very prerequisite to reduce concentration over potential at high current region and remove the water generated in cathode effectively. In this paper, fully 3 dimensional computational model which solves anode and cathode flow fields simultaneously is developed in order to compare the performance of fuel cell with parallel and interdigitated flow channels. Oxygen and water concentration and pressure drop are calculated and i-V performance characteristics are compared between flows with two flow channels. Results show that performance of fuel cell with interdigitated flow channel is hi민or than that with parallel flow channel at high current region because hydrogen and oxygen in interdigitated flow channel are transported to catalyst layer effectively due to strong convective transport through gas diffusion layer but pressure drop is larger than that in parallel flow channel. Therefore Trade-off between power gain and pressure loss should be considered in design of fuel cell with interdigitated flow channel.

• Clinical and Experimental Reproductive Medicine
• /
• v.46 no.4
• /
• pp.189-196
• /
• 2019

Objective: We aimed to evaluate the effects of different oxygen conditions (20% [high O₂], 5% [low O₂] and 5% decreased to 2% [dynamic O₂]) on mouse pre- and peri-implantation development using a novel double-channel gas supply (DCGS) incubator (CNC Biotech Inc.) to alter the oxygen concentration during in vitro culture. Methods: The high-O₂ and low-O₂ groups were cultured from the one-cell to the blastocyst stage under 20% and 5% oxygen concentrations, respectively. In the dynamic-O₂ group, mouse embryos were cultured from the one-cell to the morula stage under 5% O₂ for 3 days, followed by culture under 2% O₂ to the blastocyst stage. To evaluate peri-implantation development, the blastocysts from the three groups were individually transferred to a fibronectin-coated dish and cultured to the outgrowth stage in droplets. Results: The blastocyst formation rate was significantly higher in the low-O₂ and dynamic-O₂ groups than in the high-O₂ group. The total cell number was significantly higher in the dynamic-O₂ group than in the low-O₂ and high-O₂ groups. Additionally, the apoptotic index was significantly lower in the low-O₂ and dynamic-O₂ groups than in the high-O₂ group. The trophoblast outgrowth rate and spread area were significantly higher in the low-O₂ and dynamic-O₂ groups than in the high-O₂ group. Conclusion: Our results showed that a dynamic oxygen concentration (decreasing from 5% to 2%) had beneficial effects on mouse pre- and peri-implantation development. Optimized, dynamic changing of oxygen concentrations using the novel DCGS incubator could improve the developmental competence of in vitro cultured embryos in a human in vitro fertilization and embryo transfer program.

• 한국전산유체공학회:학술대회논문집
• /
• 2009.11a
• /
• pp.93-96
• /
• 2009

In the cathode channel of a PEM fuel cell, the local concentration of oxygen near the gas diffusion layer (GDL) decreases in streamwise direction due to chemical reactions, which degrades the efficiency of the oxygen consumption and overall fuel cell efficiency. We numerically studied the influence of the swirling flow generated by a slanted groove mixer (SGM) on the concentration distribution of oxygen. We found that the swirling flow can increase the concentration of oxygen near the GDL, and subsequently improves the oxygen consumption rate.

• The Korean Journal of Physiology and Pharmacology
• /
• v.21 no.4
• /
• pp.371-376
• /
• 2017

The caudal subnucleus of the spinal trigeminal nucleus (medullary dorsal horn; MDH) receives direct inputs from small diameter primary afferent fibers that predominantly transmit nociceptive information in the orofacial region. Recent studies indicate that reactive oxygen species (ROS) is involved in persistent pain, primarily through spinal mechanisms. In this study, we aimed to investigate the role of xanthine/xanthine oxidase (X/XO) system, a known generator of superoxide anion ($O_2{^-}$), on membrane excitability in the rat MDH neurons. For this, we used patch clamp recording and confocal imaging. An application of X/XO ($300{\mu}M/30mU$) induced membrane depolarization and inward currents. When slices were pretreated with ROS scavengers, such as phenyl N-tert-butylnitrone (PBN), superoxide dismutase (SOD), and catalase, X/XO-induced responses decreased. Fluorescence intensity in the DCF-DA and DHE-loaded MDH cells increased on the application of X/XO. An anion channel blocker, 4,4-diisothiocyanatostilbene-2,2-disulfonic acid (DIDS), significantly decreased X/XO-induced depolarization. X/XO elicited an inward current associated with a linear current-voltage relationship that reversed near -40 mV. X/XO-induced depolarization reduced in the presence of $La^{3+}$, a nonselective cation channel (NSCC) blocker, and by lowering the external sodium concentration, indicating that membrane depolarization and inward current are induced by influx of $Na^+$ ions. In conclusion, X/XO-induced ROS modulate the membrane excitability of MDH neurons, which was related to the activation of NSCC.