• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.31 no.1
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• pp.24-30
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• 2005

The flow of saliva is controlled entirely by nervous stimuli. The present study was aimed to explore the role of sympathetic and parasympathetic nerves in the regulation of sodium transporters and water channels in the salivary gland. Rats were denervated of their sympathetic and parasympathetic nerves to the submandibular gland, and the expression of sodium transporters and water channels was determined. The expression of either ${\alpha}-1$ or ${\beta}-1$ subunit of Na, K-ATPase was not significantly affected by the sympathetic denervation. On the contrary, the expression of both subunits was decreased by the parasympathetic denervation. The expression of ${\alpha}-,\;{\beta}-$, and ${\gamma}$-subunits of ENaC was not significantly affected by the sympathetic denervation, but was increased by the parasympathetic denervation. On the contrary, the expression of NHE3 was markedly decreased by both the sympathetic and the parasympathetic denervation. The sympathetic denervation significantly increased the expression of AQP1, while the parasympathetic denervation was without effect. The sympathetic and parasympathetic denervation significantly increased the expression of AQP4. The sympathetic denervation did not affect the expression of AQP5, but the parasympathetic denervation significantly decreased it. These results suggest that sympathetic and parasympathetic nerves have tonic effects on the regulation of sodium transporters and AQP water channels in the salivary gland. The sympathetic and parasympathetic denervation may then result in alterations of secretory rate and electrolyte composition of the saliva.

• Archives of Pharmacal Research
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• v.19 no.4
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• pp.264-268
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• 1996

Panax-ginseng saponin has been known to exert various pharmacological effects on cellular metabolism. This study was performed to determine the effect of ginseng saponin on gap junction channel-mediated intercellular communication, using an established in vitro system of reconstituted gap junction channels. Gap junction channels are a specialized plasma membrane fraction, which are permeable to relatively large water-soluble molecules. The sucrose permeable property of reconstituted gap junction channels was completely inhibited with 0.1 % (w/v) of ginseng saponin. We also compared the effect of ginseng saponin with that of Triton X-100, a nonionic detergent, on the same system. Triton X-100 showed significantly different effect on sucrose-permeability of gap junction channel from that was affected by ginseng saponin. The structures of liposomes containing gap junction channels was significantly destroyed by Triton X-100.

• Journal of Korea Water Resources Association
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• v.34 no.1
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• pp.57-65
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• 2001

A numerical model for analyzing transcritical flow in open channel is tested to various cases of channel shape. As the numerical models developed for transcritical flow until now mainly focused on the application to only prismatic or hypothetical channels, there are some restrictions to apply the nonprismatic channels. In this study, to verify the accuracy and stability of second-order implicit ENO scheme, the numerical model was applied to the channels which haute the varying channel bed and width. Also the numerical model was applied to unsteady flow as well as steady flow. The study shows that the numerical model provides good accuracy in the calculation of stage and velocity with no numerical oscillation, particularly in the calculation of hydraulic jump and discontinous flow Then the implicit ENO scheme demonstrated good accuracy as a high-resolution scheme and stability as an implicit scheme.

• Korean Journal of Environmental Agriculture
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• v.19 no.2
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• pp.122-127
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• 2000

A stream purification system was applied to the upper reaches of the Masan Reservoir to improve the water quality. This system consisted of two channels which were constructed on both sides of the stream, one side packed with crushed gravels and the other with plastic filter media. The system operated under low pollutant concentrations and high hydraulic loadings during a dry season to avoid clogging of the filter media. Removal rate and efficiency of chemical oxygen demand (COD) in the channel packed with crushed gravel were $14.8g/m^3/d$ and 11.5%, and for the channel with plastic filter media, $50.1g/m^3/d$ and 13.5%, respectively. Removal efficiencies of total phosphorus (T-P) were 6.6% (gravel) and 10.0% (plastic media). These results indicated plastic filter media having relatively high specific surface areas were more efficient than crushed gravels in removing pollutants. However, due to low influent water quality during dry season, the removal efficiencies were low. The proportion of nitrate nitrogen to total nitrogen (T-N) of the inflow was high but, as the system operated under aerobic condition, nitrate nitrogen could not denitrified. Accordingly, total nitrogen was not attenuated with this system. To improve the reservoir water quality effectively, this system should be able to treat the storm runoff containing higher pollutant loadings. When the filter materials are clogged by the storm runoff instead of backwashing, it would be more efficient to replace them, Therefore, the use of natural materials which are light, easily obtaining and replaceable, and have high specific surface areas is recommended.

• Membrane Journal
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• v.18 no.4
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• pp.325-335
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• 2008

In this study, we used multi-channels ceramic membrane having larger permeate volume per unit time rather than tubular membrane. The hybrid process for advanced drinking water treatment was composed of granular activated carbons (GAC) packing between module inside and outside of multi-channels microfiltration membrane. Instead of natural organic matters (NOM) and fine inorganic particles in natural water source, modified solution was prepared with humic acid and kaolin. Kaolin concentration was fixed at 30mg/L and humic acid was changed as $2{\sim}10\;mg/L$ to inspect effect of organic matters. As a result, both resistance of membrane fouling ($R_f$) and permeate flux (J) were highly influenced by concentration of humic acid. Also, in result of water-back-flushing period (FT) effect, the shorter FT was the more effective to reduce membrane fouling and to enhance permeate flux because of frequent water-back-flushing. However, the optimal FT condition was 8 min when operating costs were considered. Then, the hybrid process using multi-channels ceramic membrane and GAC was applied to lake water treatment. As a result, average treatment efficiencies in our experiment using the hybrid process were 98.02% for turbidity, 75.64% for $UV_{254}$ absorbance, 7.18% for TDS and 84.73% for $COD_{Mn}$.

• Geomechanics and Engineering
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• v.38 no.3
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• pp.215-229
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• 2024

Because of the various patterns of deep-water inrush and complicated mechanisms, accurately predicting mine water inflows is always a difficult problem for coal mine geologists. In study presented in this paper, the water inrush channels were divided into four basic water diversion structures: aquifer, rock fracture zone, fracture zone and goaf. The fluid flow characteristics in each water-conducting structure were investigated by laboratory tests, and multistructure and multisystem coupling flow analysis models of different water-conducting structures were established to describe the entire water inrush process. Based on the research of the water inrush flow paths, the analysis model of different water inrush space structures was established and applied to the prediction of mine water inrush inflow. The results prove that the conduction sequence of different water-conducting structures and the changing rule of permeability caused by stress changes before and after the peak have important influences on the characteristics of mine water-gushing. Influenced by the differences in geological structure and combined with rock mass RQD and fault conductivity characteristics and other mine exploration data, the prediction of mine water inflow can be realized accurately. Taking the water transmitting path in the multistructure as the research object of water inrush, breaking through the limitation of traditional stratigraphic structure division, the prediction of water inflow and the estimation of potentially flooded area was realized, and water bursting intensity was predicted. It is of great significance in making reasonable emergency plans.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.1154-1155
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• 2005

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.11
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• pp.559-566
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• 2015

The main objective of this work is to experimentally investigate the effect of angle variation on the distribution of two-phase flow at header-channel junctions. The cross-sections of the header and the channels were fixed at $16mm{\times}16mm$ and $12mm{\times}1.8mm$, respectively. Air and water were used as the test fluids. Four different header-channel positions were tested : Vertical header with Horizontal channels (case VM-HC), Horizontal header with Horizontal channels (case HM-HC), Horizontal header with Vertical Downward channels (case HM-VDC), and Horizontal header with Vertical Upward channels (case HM-VUC). In all cases, liquid flow distribution tended to decrease gradually in the upstream header region. However, in the downstream region, different trends could be seen. The reason for these different tendencies were identified by flow visualization in each case. The standard deviations for the liquid and gas flow distribution in each case were calculated, and the case of VM-HC had the lowest values compared to other cases because of the symmetrically distributed liquid film and strong flow recirculation near the end plate.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.11
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• pp.444-449
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• 2016

The main objective of this work is to experimentally investigate the effect of angle variation and intrusion depth of channels on the distribution of two-phase flow at header-channel junctions. The dimensions of the header and the channels in cross-section were fixed at $16mm{\times}16mm$ and $12mm{\times}1.8mm$, respectively. Air and water were used as the test fluids. Two different header-channel positions were tested : a vertical header with horizontal channels (case VM-HC) and a horizontal header with horizontal channels (case HM-HC). In all cases, the intrusion depths of the channels are 0 mm, 2 mm, and 4 mm. For the case of the intrusion depth of VM-HC, the flow distribution became more uniform. However, the intrusion depth negatively affected the flow distribution for the case of HM-HC because liquid separation delay occurred.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.6
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• pp.441-446
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• 2007

An experimental study on the countercurrent two-phase flow in narrow rectangular channels has been peformed. Countercurrent flow limitation (CCFL) was investigated using air and water in 760mm long, 100mm wide, vertical test sections with 1 and 3mm channel gaps. Tests were systematically performed with downward liquid superficial velocities and upward gas velocities covering 0 to 0.125 and 0 to 3.5m/s ranges, respectively. As the gap width of rectangular channel increased the CCFL water superficial velocity decreased for the given air superficial velocity. Slight increase of the air superficial velocity resulted in the abrupt decrease of water velocity when $j_g=2{\sim}4m/s$. The critical superficial velocity of air, at which the downward flow of water was no longer allowed, also decreased with the increase of gap width. The experimental results were compared with the previous correlations, which were mainly for round tubes, and the qualitative trends were found to be partially acceptable. However the quantitative discrepancies were hardly neglected. New correlation of CCFL was developed and showed good agreement with the experimental data.