• Membrane Journal
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• v.22 no.3
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• pp.224-233
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• 2012

To improve permeation performance of gas separation membrane, polysulfone hollow fiber membrane was prepared by wet-dry phase inversion method using Triton X-100 as non-ionic additive. And variation of gas permeation behavior by additive was investigated. Various spinning conditions such as air gap, concentration of polymer, dope tank temperature were controlled and these effects were studied. The morphology and gas permeation property of hollow fiber membranes were investigated using scanning electron microscope (SEM) and bubble flow meter respectively. We confirmed that the membranes added with Triton X-100 had a smooth external skin at various air gap length conditions. The macrovoids of these hollow fiber membranes were more developed with increase of air-gap from 4 to 90 cm and that induced higher permeance. The permeance of polysulfone membranes has the higher value at comparatively lower concentration polymer (30 wt% polysulfone) and lower concentration of additive (15 wt% Triton X-100). When temperature in dope tank was controlled, the membranes prepared at $100^{\circ}C$ showed low permeance because of volatilization of additive and solvent.

• Journal of Ocean Engineering and Technology
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• v.13 no.3B
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• pp.14-21
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• 1999

As an effective means to convey crushed materials from seabed to onboard ship and to raise hazardous or abrasive liquids, air-lift pump provides a reliable mechanism due to its simple configuration and easy-to-operate principle. The present study is focused on investigation of related performance by the analysis program based on the gas-liquid two-phase flow in circular pipes. The program covers pump operating in isothermal and vertical two-phase flow with Newtonian liquids. It is summarized as important result that an optimum air mass flow rate exists for the maximum lifted liquid mass flow rate in terms of a given submergence rates. The comparison between riser performance of the conveyed liquid flow rate calculated by the computer program and measured data with large scale air lift pump system constructed in 200 meter depth vertical tank reveals similar distribution.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.4
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• pp.121-127
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• 2008

Automatic grease lubricator is an equipment that provides adequate amount of fresh grease constantly to the shaft and bearings of machines. It minimizes the friction heat and reduces the friction loss of machines to the least. This paper is developing an automatic grease lubricator using a mode of the gas generation type from galvanic electricity. The ultimate goal of this equipment is to lubricate an adequate amount of grease with galvanic corrosion. In an electrolyte, combining anode(Mo) with cathode(Zn) is pressing out hydrogen gas of an galvanic element with galvanic reaction. The characteristics of this method is continuous flowing small hydrogen gas and controling the usage of the amount of the generation of hydrogen gas. The exterior body of grease lubricator was analyzed by Digital Mock-up of CATIA V5 and finite element analysis. The maximum stress is distributed over the outlet part where the grease lubricator suddenly narrowly contracts. The outlet part is analyzed with different constructed angle due to the different loading and setting angles. Using the analyzed design, RP trial products were producted and tested.

• Membrane Journal
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• v.22 no.2
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• pp.128-134
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• 2012

In this study, hydroxy polyimide (HPI) was prepared for non-porous membrane by solvent evaporation method. As the result of gas permeance properties measurement, $CO_2$ permeability was 85 Barrer and the $CO_2/N_2$ selectivity was 23 at $30^{\circ}C$. Flat sheet membrane and hollow fiber membrane were prepared by using ternary system of polymer, solvent and non-solvent additive. Morphologies and gas permeance properties were measured by FE-SEM and bubble flow meter. Each $CO_2$ permeability of 18.28 GPU, 70 GPU and $CO_2/N_2$ selectivity of 6.72, 8.63 at $30^{\circ}C$ in the flat sheet membrane and hollow fiber membrane. Hollow fiber membrane has gas permeance property better than flat sheet membrane.

• Magazine of the Korean Society of Agricultural Engineers
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• v.10 no.1
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• pp.1394-1408
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• 1968

The tidal discharge is defined as the quantity of water flowing through a certain cross-section per unit of time, in contrast to river discharges, tidal discharges change periodically in magnitude and direction. Thus the total volumes of water flowing into again out of the system-called flood volume and ebb volume, respectively, depend on both the tidal and the river discharges. To ditermine the tidal discharge and the flood and ebb volumes of the Yong-san river, the discharges were measured at spring, mean and neap tide and simultaneous gage reading were taken at Samhak-do, Lower Myo-do, Myongsan-ni and Naju. The general procedure for measuring the tidal discharges was as follows. First, several cross-sections were measured and one of them was chosen. First, several cross-sections were measured and one of them was chosen. Then verticals were serected in the chosen cross section. Because comparatively few verticals should be representative of the discharge distribution over the river profile, the selection was done in accordance with the somtimes irregular bottom profile. The velocities were measured with the same current meters. The observations which included water level readings were continued for a period of about 13 hours. The current direction meter, a pyramid shaped resistance body, suspend in the water on a thin wire. The bubble in a circular tilting level fixed to the wire indicates the direction of the current. Reading were taken at intervals of 1m for depths of 10m or less, and for depths over 10m at intervals of 2m, going downwards and upwards. The averages of the two velocities were used for the computation of the discharges. The discharges and the flood and ebb volumes were ditermined by a graphical method. The mean velocities, corrected for their direction when necesary, were ditermined for each time interval and each vertical, and these velocities were plotted against the time. The resulting curves show possible mistakes very clearly, and the effect of observation errors could be reduced. The corrected velocities read from the curve at half-hour intervals were multiplied by the depth at the virtical at the corresponding time. The discharges thus found were ploted against the position of the vertical in the transit and joined by a smooth curve, integration of the curve rendered the total discharges as they occurred of half-hour intervals. Plotting these total discharges against the time yeilded during the day. The flood and ebb volumes were obtained by integration of the total discharge curve.

• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.261-270
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• 2019

The separation permeation characteristics of $N_2-O_2$ gas in air at cell membrane model of skin which irradiated by high energy electron(linac 6 MeV) were investigated. The cell membrane model of skin used in this experiment was a sulfonated polydimethyl siloxane(PDMS) non-porous membrane. The pressure range of $N_2$ and $O_2$ gas were appeared from $1kg_f/cm^2$ to $6kg_f/cm^2$. In this experiment(temperature $36.5^{\circ}C$), the permeation change of $N_2$ and $O_2$ gas in non-porous membrane by non-irradiation were found to be $1.19{\times}10^{-4}-2.43{\times}10^{-4}$, $1.72{\times}10^{-4}-2.6{\times}10^{-4}cm^3(STP)/cm^2{\cdot}sec{\cdot}cmHg$, respectively. That of $N_2$ and $O_2$ gas in non-porous membrane by irradiation were found to be $0.19{\times}10^{-4}-0.56{\times}10^{-4}$, $0.41{\times}10^{-4}-0.76{\times}10^{-4}cm^3(STP)/cm^2{\cdot}sec{\cdot}cmHg$, respectively. The irradiated membrane was significantly decreased about 4-10 times than membrane which was not irradiated. And ideal separation factor of $N_2$ and $O_2$ gas by non-irradiation was found to be from 1.32 to 0.42 and that of $N_2$ and $O_2$ gas by irradiation was found to be from 0.237 to 0.125. The irradiated membrane was significantly decreased about 4-5 times than membrane which was not irradiated. When the operation change(cut) and pressure ratio(Pr) by non-irradiation were about 0, One was increased to the oxygen enrichment and the other was decreased to the oxygen enrichment. The irradiated membrane was significantly decreased about 4-19 times than membrane which was not irradiated. As the pressure of $N_2$ and $O_2$ gas was increased, the selectivity was decreased. As separation permeation characteristics of $N_2-O_2$ gas in cell membrane model of skin were abnormal, cell damages were appeared at cell.