• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.4
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• pp.274-279
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• 2008

In the perspective of saving energy in buildings, high performance of insulation and air tightness for improving the heating and the cooling efficiency has brought the positive effect in an economical view. However, these building energy saving technologies cause the lack of ventilation, which is the direct cause of increasing the indoor contaminants, and it is also very harmful to residents because they spend over 90% of their time in the indoor area. Therefore, the ventilation is important to keep indoor environment clean and it can also save energy consumption. In this study, a HEPA type breathing wall is designed as a passive ventilation system to collect airborne particles and to supply fresh outdoor air. To make fine porous structures, polymer nano fibers which were made by electro spinning method are used as a precursor. The nano fibers are coated with SiO2 nano particles and finally the HEPA type breathing wall is made by sintering in the electric furnace at $300\sim500^{\circ}C$. The pressure drops of nano ceramic structure are 8.2, 25.5 and 44.9 mmAq at the face velocity of 2.0, 5.9 and 8.8 cm/s, respectively. Also the water vapor permeability is $3.6g/m^2{\cdot}h{\cdot}mmHg$. In this research, the porous nano ceramic structures are obtained and the possibility for the usage of a material for HEPA type breathing wall can be obtained.

• Membrane Journal
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• v.22 no.3
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• pp.178-190
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• 2012

Flat sheet membranes were prepared with polysulfone (PSF) by an immersion precipitation phase inversion method. Membranes were prepared with PSF/N-methylpyrrolidone (NMP)/polyvinylpyrrolidone (PVP)/phosphoric acid casting solution and water coagulant. By using the successive process of the vapor-induced phase inversion (VIPS) followed by the nonsolvent-induced phase inversion (NIPS), the effect of phosphoric acid addition to casting solution on morphology and permeability of membrane was studied. The mean pore size, the porosity, and the water flux of membranes were increased by the addition of small amount of phosphoric acid. Furthermore, the morphology of the prepared membranes were changed from a dense sponge-like structure to highly enhanced asymmetric structure. PSF/NMP/PVP/phosphoric acid/2-butoxyethanol (BE) casting solution were prepared and cast the successive VIPS-NIPS process with same experimental condition. Due to the addition of BE to casting solution, the mean pore size and almost 0.1 ${\mu}m$ and the water flux increased about 10 to 12 $L/cm^2{\cdot}min{\cdot}bar$.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.2
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• pp.155-163
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• 2007

High Strength Concrete (HSC) has weakness that in a fire, it is spalled and brittles. The phenomenon of spalling is made by water vapor's (resulting from evaporation in the material at over $100{^{\circ}C}$)' being confined in watertight concrete. As the concrete strength increases, the degree of damage caused by the spalling becomes more serious because of the permeability. It is reported that the polypropylene(PP) fiber has an important role in protecting concrete from spalling and the optimum dosage of PP fiber is 0.2%. This study was conducted on the nonreinforced concrete specimens. The high-temperature behavior of high-strength reinforced concrete columns with various concrete strength and various dosage of PP fibers was investigated in this study. The results show that the ratio of unstressed residual strength of columns increases as the concrete strength increases and the ratio of unstressed residual strength of columns increases as the dosage of PP fiber increases from 0% to 0.2%, however, the effect of fiber dosage on residual strength of column barely changes above 0.2%.

• Food Science and Preservation
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• v.16 no.1
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• pp.134-137
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• 2009

The gelatin film containing grapefruit seed extract (GSE) was prepared by incorporating different amounts (0, 0.02, 0.05, 0.08, 0.1%) of GSE into the film. The tensile strength (TS) of the film increased by the addition of GSE, and water vapor permeability (WVP) of the film decreased. In particular, the gelatin film containing 0.1% GSE had a TS of 10.28 MPa, while the control had 8.68 MPa. WVP of the film containing 0.1% GSE decreased to 2.18 ng m/m2 s Pa, compared to 2.48 ng $m/m^{2}s$ Pa of the control. In addition, incorporation of 0.1% GSE to the gelatin film decreased the populations of Escherichia coli O157:H7 and Listeria monocytogenes by 2.67 and 3.15 log CFU/g, respectively, compared to the control. These results suggest that as a packaging material, gelatin film containing GSE can have antimicrobial activity against pathogenic microorganisms in foods.

• Korean Journal of Food Science and Technology
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• v.47 no.2
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• pp.224-232
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• 2015

The effects of cold plasma (CP) treatments on the physicochemical and biodegradable properties of a corn biomass-containing polyester (CBPE) film were studied. The CBPE film was treated with CP generated by $N_2$, $O_2$, He, Ar, or dry air at 400-900 W and 667 Pa for 10-40 min. The glass transition temperature of the CBPE film ($-30.2--28.6^{\circ}C$) was not affected by the CP treatment, while the elastic modulus and water vapor permeability decreased (p<0.05). The ink printability was improved by the treatment and the improved printability was maintained during storage for 56 days at room temperature. Roughness of the film increased after treatments and the level of roughness appeared to increase during storage. Heat and microbial biodegradability of the CBPE film was improved by the air-CP treatment (p<0.05). These results have demonstrated the potential of applying CP treatments to improve the flexibility, printability, and biodegradability of CBPE films.

• Korean Journal of Food Science and Technology
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• v.44 no.6
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• pp.711-715
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• 2012

A laminate-composite film was developed using industry co-products of defatted mustard meal (DMM) and whey protein isolate (WPI). An individually prepared DMM-based film (DMM film) and a WPI-based film (WPI film) were thermally laminated at $130^{\circ}C$ at a rate of 30 cm/min. Microscopic images exhibited that the DMM film and the WPI film were continuously attached in the laminate without void spaces. The tensile strength, elongation at break, and water vapor permeability for the laminate were 0.7MPa, 4.0%, and $6.9g{\cdot}mm/kPa/h/m^2$, respectively. Stretchability and heat seal strength of the laminate were higher than those of the un-laminated DMM film. The film layers of the laminate were physically overlapped, not forming new biopolymer units induced by molecular interactions. The opportunity for DMM films to be used as food packaging materials for wrapping and sealing could be increased by thermal lamination with WPI films, which improves the stretchability and heat sealability of DMM films.

• Journal of Microbiology and Biotechnology
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• v.16 no.4
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• pp.597-604
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• 2006

In order to extend the shelf-life of packaged or coated foods, an antibacterial edible film containing 1.8% of BLS was developed from the defatted corn germ meal, which had been fermented with Bacillus subtilis under the optimum condition of pH 7.0-7.5 and $33^{\circ}C$ for 33 h. Water vapor permeability of the fermented film $(88.3mg/cm^2\;h)$ was higher than those of the normal corn germ films $(75.8mg/cm^2\;h)$. Protein solubility of the fermented film was also higher than ordinary corn germ film at the pH range of 3-10. The fermented corn germ film had higher tensile strength and lower % elongation (elongation rate) than the ordinary corn germ film. The antimicrobial activity of the film was more than 50% of the maximum activity after film production with heat treatment at $90^{\circ}C$ and pH adjustment to 9. When the corn germ protein film with bacteriocin-like substance was applied on the mashed sausage media containing E. coli, the bacterial growth inhibition was higher than the ordinary corn protein film.

• Korean Journal of Food Science and Technology
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• v.29 no.6
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• pp.1184-1190
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• 1997

Corn zein coated carrageenan films were manufactured by immersing preformed ${\kappa}-carrageenan$ films into solution of different concentrations of corn zein (CZ) solids (10, 20, and 30% in 95% ethyl alcohol) with polyethylene glycol (20% w/w of CZ), glycerol (24% w/w of CZ). For all types of films, water vapor permeability (WVP), water solubility (WS), swelling ratio (SR), tensile strength (TS), percent elongation at break (E), heat sealing strength (HS), and Hunter color values (L, a, and b) were determined. WVP of corn zein coated ${\kappa}-carrageenan$ films decreased significantly (p<0.05) as the concentration of com zein increase. Coating with corn zein also decreased film WS and SR linearly with the concentration of corn zein. TS of corn zein coated carrageenan films decreased linearly with corn zein concentration. All the com rein coated carrageenan films showed heat sealing properties even though their sealing strength was less than half of corn zein film. Obviously corn zein coating affected color of ${\kappa}-carrageenan$ films, which was mainly caused by increase in yellowness (Hunter b-value).

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.9
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• pp.1274-1280
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• 2012

Defatted grape seed meal protein (DGP) was extracted, and DGP films containing various plasticizers were prepared. To improve the mechanical properties of DGP film, nanoclay or gelatin was incorporated in the film-forming solution to manufacture DGP composite films. Among the plasticizers of fructose (FRU), sucrose (SUC), and polypropylene glycol (PPG), DGP film containing a SUC : PPG ratio of 2.5:0.5 exhibited the best film-forming ability. Addition of Cloisite $Na^+$ improved the mechanical properties of DGP film. Tensile strength (TS) and elongation at break (E) of the film containing 5% Cloisite $Na^+$ were 1.45 MPa and 71.97%, respectively. Regarding the DGP/gelatin composite films, TS and water vapor permeability (WVP) increased with increasing gelatin amount, whereas E decreased. In particular, the DGP/gelatin (2:2) composite film exhibited 20.95 MPa TS and 12.25% E. These results suggest that the DGP film prepared from defatted grape seed meal can be used as a food packaging material.

• Nuclear Engineering and Technology
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• v.48 no.2
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• pp.457-469
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• 2016

During the late phase of severe accidents of light water reactors, a porous debris bed is expected to develop on the bottom of the flooded reactor cavity after breakup of the melt in water. The geometrical configuration, i.e., internal and external characteristics, of the debris bed is significant for the adequate assessment of the coolability of the relocated corium. The internal structure of a debris bed was investigated experimentally using the DAVINCI (Debris bed research Apparatus for Validation of the bubble-Induced Natural Convection effect Issue) test facility. Particle sedimentation under the influence of a two-phase natural convection flow due to the decay heat in the debris bed was simulated by dropping various sizes of particles into a water vessel with air bubble injection from the bottom. Settled particles were collected and sieved to obtain the particle mass, size distribution in the radial and axial positions, and the bed porosity and permeability. The experimental results showed that the center part of the particle bed tended to have larger particles than the peripheral area. For the axial distribution, the lower layer had a higher fraction of larger particles. As the sedimentation progressed, the size distribution in the upper layers can shift to larger sizes because of the higher vapor generation rate and stronger flow intensity.