• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.575-581
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• 1997

UDs were synthesized from two different polyols(PTMG, PBEAG), ionic chain extender(DMPA), EDA with $H_{12}-MDI$. PU/PMMA hybrids were prepared with free radical polymerization of MMA monomer in MMA-swelled PUD. PUD particle size and film properties were investigated ionic content and polyol type. Mechanical and thermal properties of PU/PMMA hybrid film were studied in terms of PU's ionic content and the venation of PU/PMMA compositions. As DMPA content increased from 2wt% to 10wt% in PUD, particle size of PUD decreased. PUD's particle size with ester type polyol was found to be smaller then ether type polyol used. Phase separation between hard segment(HS) and soft segment(SS) with ionic contents in PU was shown by the thermal, mechanical property measurement. Although the composition of MMA was changed from 0 to 40 wt% in PU/PMMA hybrid, the particle size of the hybrid did not increase. Using the ester type polyol, tensile strength of hybrid was found to increase by 2wt% - 6wt% DPMA content, but as higher content the strength of hybrid decreased. Moreover with the ether type polyol, tensile strength of hybrid was observed to increase by 2wt% - 4wt% DMPA content, while decreasing at higher content. PU and PMMA polymer molecule being mixed in molecular level was confirmed from the pattern of $T_g$ in DSC thermogram.

• Membrane and Water Treatment
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• v.6 no.5
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• pp.365-378
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• 2015

Herein, the preparation of anion exchange membrane (AEM) from brominated poly(2,6-dimethyl 1,6-phenylene oxide) BPPO and dimethylaniline (DMA) by phase-inversion process is reported. Anion exchange membranes (AEMs) are prepared by varying the DMA contents. Prepared AEMs show high thermal stability, water uptake (WR) around 202% to 226%, dimensional change ratios of 1.5% to 2.6% and ion exchange capacities (IECs) of 0.34 mmol/g to 0.82 mmol/g with contact angle of $59.18^{\circ}$ to $65.15^{\circ}$. These membranes are porous in nature as confirmed by SEM observation. The porous property of membranes are important as it could reduce the resistance of transportation of ions across the membranes. They have been used in diffusion dialysis (DD) process for recovery of hydrochloric acid (HCl) from the mixture of HCl and ferrous chloride ($FeCl_2$). Presence of $-N+(CH_3)_2C_6H_5Br^-$ as a functional group in membrane matrix facilitates its applications in DD process. The dialysis coefficients of hydrochloric acid ($U_H$) of the membranes are in range of 0.0016 m/h to 0.14 m/h and the separation factors (S) are in range of 2.09 to 7.32 in the $HCl/FeCl_2$ system at room temperature. The porous membrane structure and presence of amine functional group are responsible for the mechanism of diffusion dialysis (DD).

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.1
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• pp.89-95
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• 2009

The current enforce decree of "The Act on the Promotion of Construction Waste Recycling" divides seventeen kinds of construction wastes by property and configuration. Mixed construction waste, one of them classified by the enforce decree, is composed two more than justified construction wastes except refuse soil and rock. In construction wastes justified by enforce decree of this law, most refuse concrete and asphalt concrete of construction wastes are recycled. As well as refuse metal is separated, sorted from bulk them, and merchandised for value. Finally this is used the secondary manufactured products. Even though combustible construction wastes like refuse wood, plastics, fiber can be recycled RDF(Refuse derived fuel) or RPF(Refuse plastic fuel) because of high caloric value and low heavy metal but most of them are discharged as mixed construction waste and then treated by treated by incineration and landfill. Therefore, to control construction waste flow efficiently, construction wastes are classifies first combustible, incombustible, mixed combustible, incombustible and etc. in this study. The combustible waste is consisted refuse wood, plastics, fiber and etc. and incombustible waste contains refuse concrete, asphalt, and etc. Mixed construction is construction waste that can not separate from mixed waste bulk with different kinds.

• Membrane Journal
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• v.23 no.2
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• pp.151-158
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• 2013

The effect of layered double hydroxides (LDH) on the gas separation properties of ethylene vinyl acetate copolymer was investigated. Mg-Al LDH/EVA nanocomposite membranes were prepared from solution intercalation using organically modified LDH (DS-LDH). Dodecyl sulfate (DS)-LDH was obtained by the intercalation of DS anion in the interlayer. The nanocomposite structure has been elucidated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). XRD pattern clearly shows that the DS-LDH layers are disorderly well dispersed in the EVA matrix. The maximum tensile strength and elongation of the LDH/EVA nanocomposite membrane were found with the LDH content 3 wt%. The thermal properties of nanocompostie membrane were enhanced by the incorporation of LDH in EVA matrix. Gas permeation of LDH/EVA nanocomposite membranes with LDH contents of 1, 3, 5 wt% was studied for $O_2$ and $CO_2$ single gases. The presence of 3 wt% LDH decreased $O_2$ permeability by up to 53% compared to the EVA membrane. In spite of barrier property of nanocomposite membrane, however, the gas permeability for $CO_2$ was increased due to its strong affinity with the residual OH groups on the LDH.

• Applied Chemistry for Engineering
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• v.24 no.6
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• pp.639-644
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• 2013

In this study, ethosomes loaded with Eucommia ulmoides extracts that have anti-inflammatory and anti-aging activities on the skin were prepared as cosmetic materials. The particle size, physical property, and entrapment efficiency of ethosomes to identify their stabilities during 4 weeks were measured. Ethosomes containing 0.01~0.05% E. ulmoides extracts did not show either precipitation or separation. The mean particle size of these ethosomes was 136.4 nm, and monodisperse. The particle size of ethosome containing 0.05% E. ulmoides extracts was 151.15 nm and the entrapment efficiency was 81.79%. Therefore, in vitro skin permeation experiment was performed with ethosome containing 0.05% E. ulmoides extracts that showed the high loading efficiency and stability during 4 weeks. The order of skin permeation of E. ulmoides extracts was ethosome (77.16%) > liposome (62.80%) > ethanolic solutoin (41.59%). These results suggest that ethosomes containing 0.05% E. ulmoides extracts are effective for the skin permeation and may be used as a cosmetic formulation containing plant extracts.

• Fire Science and Engineering
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• v.34 no.4
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• pp.52-58
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• 2020

The number of medical welfare facilities caring for the elderly with paralysis and dementia has been increasing rapidly because of the change in the way of supporting the elderly, stemming from an increase in the number of the elderly and working couples. These medical welfare facilities are usually installed all over the city and are gradually becoming high-rise. Few inmates are capable of making their own decisions in case of fire at night and when there are no escape routes such as ramps for evacuation, leading to massive casualties. This study aimed to identify problems in evacuation in the medical welfare facilities for the elderly in Goyang city. This city has the largest number of medical welfare facilities for the elderly per unit area. The following strategies could aid in better evacuation: secure ramps or bed escape elevators; the bedrooms of the inmates should have one-hour fire resistance; the stairs should have the structure of an enclosed stairway; the necessary apparatus for evacuation, such as an escape chute, should be installed; and, to conclude, a business agreement with neighboring agencies to help inmates escape during the fire. The state should implement necessary measures to protect the lives and property of the people. Rapid implementation of this proposal is necessary for the evacuation safety of an increasing number of medical welfare facilities for the elderly.

• Journal of the Korean Institute of Gas
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• v.11 no.4
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• pp.91-97
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• 2007

Recently, during the past five years, accidents of gas boiler using city gas have occurred 7.4 times more than those which use LP gas. The number of accidents has increased since the use of city gas boilers has increased. These boiler accidents resulted in 87% death from poisoning of CO, and casualty of the accidents was 4.3 times more than that of other types of accident. Hence this study makes the cause of accidents clear by separation the exhaust tube which is the cause of CO poisoning. Also, this study will establish the safety of heat-resistant silicon through testing the performance of heat-resistant silicon. The experiment showed that common silicon started hardening at $56^{\circ}C$ while the heat-resistant silicon did not begin carbonization until $606^{\circ}C$. Besides at the temperature of $150^{\circ}C$ which is the normal temperature of exhaust tube, common silicon leaked on the pneumatic test after deterioration, but the heat-resistant silicon maintained its original property. With these results, we judge that we can reduce the casualty by CO poisoning if we use the heat-resistant silicon to the connector of he exhaust tube.

• Polymer(Korea)
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• v.33 no.6
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• pp.537-543
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• 2009

The direct fluorination of polymers is a heterogeneous reaction using the mixture of $F_2$ and inert gas. In general, the resulting fluorinated polymers have good barrier property chemical stability similar to those of the fluoro-polymers, and could be prepared from the simple process. In this study, the polysulfone dense films were surface fluorinated using the direct fluorination technique and gas permeability and selectivity of the prepared membranes were measured with varying both $F_2$ concentration and reaction time. The introduction of $F_2$ was confirmed by X-ray photoelectron spectroscopy (XPS), water contact angles, and atomic force microscopy (AFM). As the $F_2$ increased, the permeability decreased while the selectivities for $O_2$, $CO_2$, and He gases relative to $N_2$ increased.

• Membrane Journal
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• v.19 no.4
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• pp.261-267
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• 2009

Polyimide which is the glassy polymer has high chemical resistance, thermal stability and high mechanical property. In this study, the polyimide hollow fiber membranes were prepared by the dry-jet wet phase inversion in order to investigate the permeation porperties of the $H_2S$ and $CH_4$. The morphology of prepared hollow fiber membranes and their permeation behaviors of $H_2S$ and $CH_4$ before and after silicon coating were evaluated. The permeance of $H_2S$ and $H_2S/CH_4$ selectivity increased due to plasticization with increasing the feed pressure. The permeance of KSM03b and selectivity of KSM03d were highest among the three type membranes used this experiments. The permeance decreased but the $H_2S/CH_4$ selectivity increased with increasing the air gap. The permeance reduced after silicon coating. However, the selectivity increased and the selectivity of KSM03d was 275 at 7 atm.

• Fire Science and Engineering
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• v.31 no.5
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• pp.37-43
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• 2017

Domestic sandwich panel buildings are widely used on walls and roofs of factories and warehouse facilities. Factory and warehouse facilities have high fire load and rapid spread of fire due to their use characteristics, leading to large fires. Due to the characteristics of materials, walls and roofs are collapsed, resulting in life damage and property damage. In this regard, this study examined domestic and international standards of sprinkler facilities to prevent ignition of sandwich panel walls. Also, in order to check whether the fire was prevented by installing the head on the wall of the sandwich panel, the fire test was carried out with 10 cm, 60 cm, and 120 cm from the wall along the sprinkler head installation standard of domestic fire safety standards. As a result of the fire test, it was confirmed that the sandwich panel was prevented from igniting when the head of water pressure 0.1 MPa and water quantity K-80 was installed. According to the separation distance, it was impossible to measure the temperature at 10 cm, but at 60 cm, At the maximum temperature of $525^{\circ}C$ and 120 cm, the maximum temperature of the wall of the sandwich panel was measured as $276^{\circ}C$. As a result of the fire test, considering the fire point of 450 degrees Celsius in the fire test of the sandwich panel, the distance from the sandwich panel wall to the combustible is more than 120 cm.