• Membrane Journal
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• v.15 no.2
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• pp.147-156
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• 2005

It is well-known that polyethersulfone (PES) has high $CO_2$ selectivity over $N_2\;(or\;CH_4)$ and excellent pressure resistance of $CO_2$ plasticization among muy commercialized engineering plastics[1-4]. Asymmetric PES hollow fiber membranes for flue gas separation were developed by dry-wet spinning technique. The dope solution consists of PES, NMP and acetone. Water and water/NMP mixtures are used in outer and inner coagulants, respectively. Gas permeation rate (i.e., permeance) and $CO_2/N_2$ selectivity were measured with pure gas, respectively and the micro-structure of hollow fiber membranes was characterized by scanning electron microscopy. The effects of polymer concentration, ratio of NMP to acetone, length of air gap, evaporation condition and silicone coating were investigated on the $CO_2/N_2$ separation properties of the hollow fibers. Optimized PES hollow fiber membranes exhibited high permeance of $25\~50$ GPU and $CO_2/N_2$ selectivity of $30\~40$ at room temperature and have the apparent skin layer thickness of about $0.1\;{\mu}m$. The developed PES hollow fiber membranes, would be a good candidate suitable for the flue gas separation process.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.3
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• pp.13-20
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• 2011

In this paper, we proposed a system to raise gas safety management by using the wireless communication module and intelligent gas safety appliances. Our designed systems configure a micom-gas meter, an automatic extinguisher, sensors, and a wallpad. A micom-gas-meter monitors gas flow, gas pressure, and earthquake. An automatic fire extinguisher checks gas(combustible) leaks and temperature of $100^{\circ}C$ and $130^{\circ}C$. Sensors measure smoke and CO gas. In our novel system, a micom-gas meter cut off inner valve with warnings, an automatic fire extinguisher cut off middle valve and spray extinguishing materials, and sensors generate signals for smoke and CO when occurring gas risk. Gas safety appliances and sensors takes safety measures, and transmit those signal to a wallpad. The wallpad again transmit signal like events to a control server. Users can connect web pages for gas safety through B-ISDN and control and manage them. We hereby devised scenarios for gas safety and risk management, and demonstrated their effectiveness through experiments.

• Clean Technology
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• v.26 no.1
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• pp.1-6
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• 2020

Rapid expansion of supercritical solution (RESS) process was used to make molsidomine (MOL) loaded peracetyl-β-cyclodextrin (PAc-β-CD) nanoparticles, which were collected into the air. The effect of the concentration of the drug PAc-β-CD (0.5 and 1 wt%), extraction temperature (45 ~ 60 ℃), nozzle length (5 ~ 20 mm) and internal diameter (ID) (50 ~ 150 μm) of a capillary, and spray distance on the particle size and morphology of the resulting particles were investigated. The interaction of a drug and PAc-β-CD was confirmed by ¹H-NMR spectroscopy while the particle size was measured by means of a scanning electron microscope. It was found that increasing the temperature from 45 ℃ to 60 ℃ and decreasing the nozzle diameter from 150 μm to 50 μm had an increasing effect on the average particle size, while increasing the spray distance led to a decrease in the average particle size at a constant pressure of 34.5 MPa and temperature of 45 ℃. With 0.5 wt% of PAc-β-CD, the capillary nozzle of short length (5 mm) and small ID (50 μm) gave the smallest size (165 nm). The obtained nanoparticles showed increased dispersity and solubility in oil. The oil suspension of the inclusion complex showed increased sustainability, which can increase the in-vitro controlled release time of the drug.

• Journal of the Korean Ceramic Society
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• v.41 no.5
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• pp.410-416
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• 2004

In this study, we fabricated magnetite coated on a cordierite honeycomb which has complex shape by ultrasound-enhanced ferrite plating. The effects of the plating condition on the formation of the magnetite and its microstructure were investigated. The magnetite coated on the honeycomb became an oxygen-deficient ferrite by H$_2$ gas reduction, then the effects of the molar concentrations of ammonium acetate for $CO_2$ gas decomposition have been studied. As the molar concentration of a pH buffer($CH_3$COONH$_4$, 0.1946∼0.3892 M) solution increased, the average particle size increased about 200∼250 nm. The magnetite coated on the honeycomb was reduced by H$_2$ gas for 2 h at 30$0^{\circ}C$. The inner pressure change in the cell began to occur at 315∼34$0^{\circ}C$. The H$_2$-Reduced magnetite coated on the honeycomb at 35$0^{\circ}C$ contained an oxygen deficient magnetite and $\alpha$-Fe phase. The thermogravimetric analysis with H$_2$ reduction and $CO_2$ decomposition were carried out with the magnetite coated on the honeycomb. A weight loss in process of H$_2$ reduction occurred between 32$0^{\circ}C$ and 34$0^{\circ}C$, while a weight gain was observed during the $CO_2$ decomposition.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.400-403
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• 2002

The fundamental experiments for measuring soft x-ray characteristics from the vacuum capillary are described. These experiments were primarily performed in order to generate line spectra such as x-ray lasers. The generator consists of a high-voltage power supply, a polarity-inversion ignitron pulse generator, a turbo-molecular pump, and a radiation tube with a capillary. A high-voltage condenser of 200 nF in the pulse generator is charged up to 20 kV by the power supply, and the electric charges in the condenser are discharged to the capillary in the tube after closing the ignitron. During the discharge, weakly ionized plasma forms on the inner and outer sides of a capillary. In the present work, the pump evacuates air from the tube with a pressure of about 1 mPa, and a demountable capillary was developed in order to measure x-ray spectra according to changes in the capillary length. In this capillary, the anode (target) and cathode elements can be changed corresponding to the objectives. The capillary diameter is 2.0 mm, and the length is adjusted from 1 to 50 mm. When a capillary with aluminum anode and cathode electrodes was employed, both the cathode voltage and the discharge current almost displayed damped oscillations. The peak values of the voltage and current increased when the charging voltage was increased, and their maximum values were -10.8 kV and 4.7 kA, respectively. The x-ray durations observed by a 1.6 ${\mu}$m aluminum filter were less than 30 ${\mu}$s, and we detected the aluminum characteristic x-ray intensity using a 6.8 ${\mu}$m aluminum filter. In the spectrum measurement, two sets of aluminum and titanium electrodes were employed, and we observed multi-line spectra. The line photon energies seldom varied according to changes in the condenser charging voltage and to changes in the electrode element. In the case where the titanium electrode was employed, the line number decreased with corresponding decreases in the capillary length. Compared with incoherent visible light, these rays from the capillary were diffracted and diffused greatly after passing through two slits.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4B
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• pp.369-376
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• 2011

A three and two dimensional (3D and 2D) numerical models were established to study the storm surge induced by Typoon Maemi in Masan and Pusan Ports. The typhoon landed on the southern coast of Korean Peninsula at 21:00, September 12, 2003 with a central pressure of 950 hPa. The observed maximum storm surge in Masan Port was 230 cm, and the computed peak storm surge using the 3D and the 2D models were 238 cm and 208 cm, respectively. The observed maximum storm surge in Pusan Port was 89 cm, and the peak storm surge of the 3D and the 2D models were 91 cm and 79 cm, respectively. The hindcasted storm surge using 3D model was in good agreement with the observed data, and the 3D model at peak time was more accurate than the 2D. The storm-induced currents were computed using the 3D model. The currents in the surface layer of Masan Bay went into the inner bay with 30~60 cm/sec, while the currents in the bottom layer flowed out with 20~40 cm/sec.

• Journal of the Korean Association of Geographic Information Studies
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• v.1 no.1
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• pp.86-98
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• 1998

In order to provide an information as input data of possible storm surges in advance, the typhoon center and maximum wind position analysis scheme must be developed for the initialization of pressure and wind field.This study proposes a semi-automatical and objective analysis method and a procedure on a real time basis using the satellite TBB data of the GMS IR1, NOAA satellite CH4 and CH5, and shows the result of an experimental analysis. It includes a simple method of determining the parameters of the typhoon using minimum top temperature of the convective cloud near the inner eyewall. The method analyzing the isotropic cross sectional variation of TBB gradient from center to environment was developed to determine the center of Rmax of typhoon. This position of intense eyewall from typhoon center can be considered as the position of maximum wind. The results of estimation of typhoon center show very good agreement to the results of synoptic analysis. It is found that the Rmax is approximately 50-200km. From the comparison of the GMS and NOAA IR TBB data, it is found that the Rmax from NOAA data tends to be longer than those from GMS data.

• Tunnel and Underground Space
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• v.24 no.1
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• pp.67-80
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• 2014

Long-term stability and delayed failure of granite were evaluated through the laboratory test based on Wilkins method and Brazilian disc test (BDT) which yields tensile strength, mode I fracture toughness and subcritical crack growth parameters. Then, the long-term strength of granite was estimated by using analytical models and long-term stability of compressed air-energy storage (CAES) pilot cavern pressurized up to 5 ~ 6 MPa was evaluated using numerical code, FRACOD with the determined subcritical crack growth parameters. The results of test and analyses showed that the subcritical crack growth index, n was determined as 29.39 and the inner pressure of 5 ~ 6 MPa had an insignificant effect on the long-term stability of pilot cavern. It was also found that the measurement and analysis of acoustic emission events can describe the accumulation of damage due to subcritical crack growth quantitatively. That is, AE monitoring can provide the current status of rock under loading if we make an identical installation condition in the field with that of the laboratory test.

• The Journal of Engineering Geology
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• v.23 no.3
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• pp.247-256
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• 2013

The carbonate sands of the Sabkha layer in the Middle East have very low shear strength. Therefore, instant settlement and time-dependent secondary settlement occur when inner voids are exposed, as in the case of particle crushing. We analyzed settlement of the Sabkha layer under a large-scale foundation by hydrotesting, and compared the field test results with the results of laboratory tests. With ongoing particle crushing, we observed the following stress-strain behaviors: strain-hardening (Sabkha GL-1.5 m), strain-perfect (Sabkha GL-7.0 m), and strain-softening (Sabkha GL-7.5 m). General shear failure occurred most frequently in dense sand and firm ground. Although the stress-strain behavior of Sabkha layer carbonate sand that of strain-softening, the particle crushing strength was low compared with the strain-hardening and strain-perfect behaviors. The stress-strain behaviors differ between carbonate sand and quartz sand. If the relative density of quartz sand is increased, the shear strength is also increased. Continuous secondary compression settlement occurred during the hydrotests, after the dissipation of porewater pressure. Particle crushing strength is relatively low in the Sabkha layer and its stress-strain behavior is strain-softening or strain-perfect. The particle crushing effect is dominant factor affecting foundation settlement in the Sabkha layer.

• Journal of Preventive Medicine and Public Health
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• v.27 no.1 s.45
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• pp.59-73
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• 1994

The purpose of this study is to experiments the environmental conditions and the adaption of the human body in the vinyl house. The study was done in spring and winter and experimental clothes were used working clothes in the vinyl house. The results are as follows. 1. Environmental Conditions In the spring season, the indoor air temperature was $27.4{\pm}3.7^{\circ}C$ and the outdoor air temperature was $14.4{\pm}2.7^{\circ}C$. In the winter season, the indoor air temperature was $18.3{\pm}4.8^{\circ}C$ and the outdoor air temperature was $7.6{\pm}2.5^{\circ}C$ on the average. 2. Skin Temperature In the spring season, the mean skin temperatures indoor and outdoor were $33.81{\pm}0.7^{\circ}C\;and\;31.57{\pm}0.8^{\circ}C$ respectively, a difference of $2.24^{\circ}C$. In the winter season, they were $31.95{\pm}1.93^{\circ}C\;and\;29.86{\pm}0.55^{\circ}C$ respectively, a difference of $2.09^{\circ}C$. 3. Clothing Climate In the spring season, the temperature and humidity in the inner layer of clothing were $34.77{\pm}0.80^{\circ}C\;and\;70.75{\pm}1.65%$ indoor, $31.9{\pm}0.52^{\circ}C\;and\;51.9{\pm}3.70%$ outdoor respectively. In the winter season, those were $32.52{\pm}1.04^{\circ}C\;and\;64.65{\pm}3.68%$ indoor, $30.27{\pm}0.96^{\circ}C\;and\;45.07{\pm}2.68%$ outdoor respectively. 4. Physiological Factors Body temperature increased slightly and the pulse rate also rises, but blood pressure decreased a little with the rise of environmental temperature both in the spring and winter seasons. 5. Psychological Factors Thermal sensation in the spring season was expressed as 'slightly warm' or 'warm' indoor and as 'neutral' in the open air, while in the winter it was expressed as 'neutral' or 'slightly warm' outdoor the house and as 'cold' in the open air. Comfort sensation was characterized as 'uncomfortable' or 'slightly uncomfortable' indoor both in the spring and winter seasons, but in the open air it was characterized as 'comfortable' in the spring and as 'slightly uncomfortable' in the winter.