• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.297-302
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• 2018

Bead type and hollow fiber type catalyst (HFC, Hollow Fiber type Catalyst) was prepared by $La_{0.1}Sr_{0.9}Co_{0.2}Fe_{0.8}O_{3-{\delta}}$ (LSCF1928) perovskite powder catalyst which showed excellent methane complete oxidation characteristics through previous studies. The HFC have a cylindrical shape with an empty interior, and pores can be formed through Phase inversion method so the specific surface area can be remarkably improved. In the case of the bead type catalyst prepared by adding Methyl Cellulose (MC), $SrCO_3$ was produced in addition to the original catalyst composition of LSCF1928 due to the reaction of $CO_2$ emitted from MC and Sr of the catalyst. In the case of the HFC, a single phase perovskite structure was obtained without impurities. The HFC calcined at $700{\sim}900^{\circ}C$ showed pore structure of finger-sponge-finger structure, and 99.9% oxygen conversion rate was achieved through complete oxidation of methane at $475^{\circ}C$. Air gap and spinning pressure condition were changed to control the HFC pore. 2 cm air gap and 7 bar spinning pressure showed the best catalytic performance and achieved oxygen conversion rates of more than 70.65%, 93.01%, and 99.99% at $425^{\circ}C$, $450^{\circ}C$ and $475^{\circ}C$, respectively.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.4
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• pp.598-607
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• 2008

Bast fibers were applied for various usages from fabrics to household care products long time ago. In this study, we investigated the physical characteristrus of water retted & chemically rotted fibers of Yucca, New Zealand hemp, Corn, Kuzu vine, Indian mallow, and Mulberry paper that have been harvested by domestic cultivation. Water retting is more effective than chemical rotting for six kinds of plant fibers. When all fibers were rotted chemically with 1% sodium hydroxide, only Kuzu vine and Indian mallow were retted. Indian mallow, Yucca, New Zealand hemp, and Com fibers have higher tensile strength than any other fibers. The crystallinity of Kuzu vine, Indian mallow, Yucca, New Zealand hemp, and Corn was as low as 60% but Yucca, New Zealand hemp were flexible. Yucca had fewer lumina whereas New Zealand hemp more lumina in cross sectional shape. Especially com fibers have a structure like sponge, and Indian mallow had a net shape. The longitudinal section of New Zealand hemp showed smooth and long shape. Mulberry paper was proved to be short and thin, which is quite appropriate for making paper. In this study, we found that plant fibers for living material could be used for cloth materials.

• Journal of Periodontal and Implant Science
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• v.28 no.4
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• pp.559-568
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• 1998

direct bone apposition during bone remodelling. To address these problem, we developed a new ceramic, calcium metaphosphate(CMP), and report herein the biologic response to CMP in subcutaneous tissue, muscle and bone. Porous CMP blocks were prepared by condensation of anhydrous $Ca(H_2PO_4)_2$ to form non-crystalline $Ca(PO_3)_2$. Macroporous scaffolds were made using a polyurethane sponge method. CMP block possesses a macroporous structure with approximate pore size range of 0.3-1mm. CMP blocks were implanted in 8mm sized calvarial defect, subcutaneous tissue and muscle of 6 Newzealand White rabbits and histologic observation were performed at 4 and 6 weeks later. CMP blocks in subcutaneous tissue and muscle were well adapted without any adverse tissue reaction and resorbed slowly and spontaneously. Histologic observation of calvarial defect at 4 and 6 weeks revealed that CMP matrix were mingled with and directly apposed to new bone without any intervention of fibrous connective tissue. CMP blocks didn't show any adverse tissue reaction and resorbed spontaneously also in calvarial defect. This result revealed that CMP had a high affinity for bone and was very biocompatible. From this preliminary result, it was suggested that CMP was a promising ceramic as a bone substitute and tissue engineering scaffold for bone formation.

• Membrane Journal
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• v.19 no.1
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• pp.63-71
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• 2009

In this study, polysulfone which has excellent mechanical and thermal stability with low cost was used for preparing a non-conducting polymer matrix as a reinforced composite membrane for fuel cell application. The membranes were prepared by phase separation method. Polymer concentration and retention time were controlled to investigate the effects on the membrane morphology. The resaltant membranes showed all sponge-like structure independent of polymer concentration. The mechanical and thermal stability were improved with increasing polymer concentration in contrast to the membrane porosity. As a result, the membranes prepared with the retention time for 2 mins using 20 wt% of polymer solution was suitable for a fuel cell compositite membrane providing optimum properties such as approximately 80% of high porosity, 1.3 MPa of tensile strength, and less than 1% of thermal shrinkage both machine and transverse direction.

• Membrane Journal
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• v.18 no.4
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• pp.317-324
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• 2008

Polysulfone membranes were prepared via the phase inversion process. With propionic acid as a nonsolvent additive, polysulfone casting solutions were solidified in an isopropanol bath. Propionic acid (PA) worked as a thermodynamic enhancer for phase separation and as a rheological suppressor for kinetic hindrance. Morphology of the prepared membranes significantly varied with propionic acid content in the casting solution. The dense skin layer, which was identified in the membrane prepared without PA, almost disappeared in the membrane prepared trom PA 10wt%. With 30wt% PA, the membrane revealed the morphological gradient from a nodular skin structure to a sponge-like substructure, including the finger-like cavity. Water permeability increased with PA content, and polyethylene glycol rejection decreased with the nonsolvent content.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.1
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• pp.476-496
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• 2018

With the advancement and deployment of wireless communication techniques, wireless body area network (WBAN) has emerged as a promising approach for e-healthcare that collects the data of vital body parameters and movements for sensing and communicating wearable or implantable healthful related information. In order to avoid any possible rancorous attacks and resource abuse, employing lightweight ciphers is most effective to implement encryption, decryption, message authentication and digital signature for security of WBAN. As a typical lightweight cryptosystem with an extended sponge function framework, the PHOTON family is flexible to provide security for the RFID and other highly-constrained devices. In this paper, we propose a differential fault analysis to break three flavors of the PHOTON family successfully. The mathematical analysis and simulating experimental results show that 33, 69 and 86 random faults in average are required to recover each message input for PHOTON-80/20/16, PHOTON-160/36/36 and PHOTON-224/32/32, respectively. It is the first result of breaking PHOTON with the differential fault analysis. It provides a new reference for the security analysis of the same structure of the lightweight hash functions in the WBAN.

• Applied Chemistry for Engineering
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• v.19 no.6
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• pp.633-639
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• 2008

Polysulfone membranes were prepared via the phase inversion process. Toluene was added as a nonsolvent additive in the casting solution containing a mixture of polysulfone and n-methylpyrrolidone. When prepared via the diffusion-induced process using isopropanol as a precipitation nonsolvent, the solidified membranes revealed a similar asymmetric structure irrespective of the addition of toluene, presenting both a dense skin layer and a sponge-like support layer. The added toluene played a role of enhancing liquid-liquid phase separation of the casting solution, and skin layer thickness of a prepared membrane increased with toluene content in the casting solution. On membrane performance, the solute rejection showed a uniform behavior irrespective of the addition of toluene. However, in spite of the significant increase in dense skin layer thickness, the water permeation through the membrane prepared with 60 wt% toluene revealed five times as much flux, compared with that of the membrane prepared without toluene additive.

• Journal of the Korean Wood Science and Technology
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• v.38 no.3
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• pp.205-212
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• 2010

This study was carried out to investigate the characterization of aerogel made by holocellulose, the thermal properties of the aerogel, and its shapes and porous structures. The aerogel was made by holocellulose through the gelation in alkali hydroxide-urea solution and freeze drying processes. Holocellulose aerogel had porous structure such as net or sponge. The density of holocellulose aerogel was 0.04 g/$cm^3$, and the specific surface area 145.3 $m^2$/g. Although thermal degradation occurred in the range of $210{\sim}350^{\circ}C$, significant thermal degradation occurred at low temperature with low heating rate, Micropore volume was sharply increased with low heating rate. Holocellulose aerogel char obtained by carbonization with $900^{\circ}C$ and $0.5^{\circ}C$/min. heating rate had the highest surface area, 656.7 $m^2$/g. The deformed and irregular structures of holocellulose aerogel chars due to the thermal degradation were observed in SEM.

• Membrane Journal
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• v.23 no.2
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• pp.119-128
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• 2013

In this research, PEI/PEBAX composite hollow fiber membrane was used for the removal of water vapor from gases. PEI (Polyetherimide) substrate membrane was spinned by dry-wet phase inversion method and coated with PEBAX (Polyether block amides) 3533 and PEBAX1657. Fabricated fibers typically had an asymmetric structure of a dense top layer supported by a sponge-like substructure through scanning electron microscopy (SEM). $H_2O/N_2$ mixture gas was used to compare the performance of separation according to temperature, pressure and water activity. The results of PEBAX3533 and PEBAX1657 composite membranes respectively showed $H_2O/N_2$ selectivity of 61.7~118.5 and 85.3~175.4 according to operating conditions. PEBAX3533 composite hollow fiber membranes module showed the water vapor removal of 90%.

• Korean journal of food and cookery science
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• v.21 no.6 s.90
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• pp.782-793
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• 2005

This study investigated the effect of $2\%$ addition of pectin and alginate on the Physicochemical and retrogradation Properties of Jeungpyun, a Korean traditional fermented rice cake. The volume of batters with alginate and Pectin was significantly larger than that of control. Jeungpyun samples with Pectin and alginate had a larger volume with uniform and smaller cell size. All samples showed largest foaming capability after second fermentation. Foaming capability of the control ($0\%$ addition of pectin and alginate) was significantly larger than that of the treated samples. The amount of reducing sugar tended to increase during fermentation but decreased after steaming, which was due to the increase in hydrolysis of starch. On the contrary, the content of free sugar was slightly decreased during fermentation but slightly increased after steaming. The control contained the largest amount of free sugar after steaming. The microstructure of starch particles after fermentation showed completely dispersed starch granules with air bubbles. After steaming, the structure was sponge-like in all samples. Samples with added alginate and pectin had significantly higher water binding capacity than those of the control. All samples showed noticeably increased solubility and swelling power at $70^{circ}C$ with the control being significantly lower than the treated samples. Retrogradation was measured with $\alpha$-amylase and the retrogradation process of the sample with added alginate and pectin proceeded slower than that of the control. The relative crystallinity was observed through X-ray diffraction method and samples with added alginate and pectin had smaller crystallinity and delayed retrogradation compared to the control. Thus, Jeungpyun with the addition of alginate and Pectin demonstrated improved functionality and dietary fiber addition effect. The storage period of was extended as the retrogradation rate was delayed by the addition of dietary fibers.