• BMB Reports
• /
• v.56 no.12
• /
• pp.645-650
• /
• 2023

Numerous studies have investigated the cellular prion protein (PrP^C) since its discovery. These investigations have explained that its structure is predominantly composed of alpha helices and short beta sheet segments, and when its abnormal scrapie isoform (PrPSc) is infected, PrPSc transforms the PrP^C, leading to prion diseases, including Creutzfeldt-Jakob disease in humans and bovine spongiform encephalopathy in cattle. Given its ubiquitous distribution across a variety of cellular types, the PrP^C manifests a diverse range of biological functions, including cell-cell adhesion, neuroprotection, signalings, and oxidative stress response. PrP^C is also expressed in immune tissues, and its functions in these tissues include the activation of immune cells and the formation of secondary lymphoid tissues, such as the spleen and lymph nodes. Moreover, high expression of PrP^C in immune cells plays a crucial role in the pathogenesis of prion diseases. In addition, it affects inflammation and the development and progression of cancer via various mechanisms. In this review, we discuss the studies on the role of PrP^C from various immunological perspectives.

• Journal of the Korean Wood Science and Technology
• /
• v.46 no.1
• /
• pp.73-84
• /
• 2018

Recently, the importance of flame retardation treatment technology has been emphasized due to the increase in urban fire accidents and fire damage incidents caused by building exterior materials. Particularly, in the utilization of wood-based building materials, the flame retarding treatment technology is more importantly evaluated. An Intumescent system is one of the non-halogen flame retardant treatment technologies and is a system that realizes flame retardancy through foaming and carbonization layer formation. To apply the Intumescent system, composite material was prepared by using Ethylene vinyl acetate (EVA) as a matrix. To enhance the flame retardant properties of the Intumescent system, a nano-clay was applied together. Composite materials with Intumescent system and nano - clay technology were processed into sheet - like test specimens, and then a new structure of cross laminated timber with improved flame retardant properties was fabricated. In the evaluation of combustion characteristics of composite materials using Intumescent system, it was confirmed that the maximum heat emission was reduced efficiently. Depending on the structure attached to the surface, the CLT had two stages of combustion. Also, it was confirmed that the maximum calorific value decreased significantly during the deep burning process. These characteristics are expected to have a delayed combustion diffusion effect in the combustion process of CLT. In order to improve the performance, the flame retardation treatment technique for the surface veneer and the optimization technique of the application of the composite material are required. It is expected that it will be possible to develop a CLT structure with improved fire characteristics.

• Journal of Adhesion and Interface
• /
• v.7 no.1
• /
• pp.16-22
• /
• 2006

In this work, the effect of cure temperature and time on the thermal stability and the exothermic cure reaction peak of a waterborne resol-type phenol-formaldehyde resin, which may be used for preparing phenolic sheet molding compounds (SMC), has been investigated using a thermogravimetric analyzer and a differential scanning calorimeter. The weight loss of waterborne phenol-formaldehyde resin was mainly occurred at three temperature stages: near $200^{\circ}C,\;400^{\circ}C$, and $500^{\circ}C$. The carbon yield at $750^{\circ}C$ for the cured resin was about 62%~65%. Their thermal stability increased with increasing cure temperature and time. Upon cure, the exothermic reaction was taken placed in the range of $120^{\circ}C{\sim}190^{\circ}C$ and the maximum peak was found in between $165^{\circ}C$ and $170^{\circ}C$. The shape and the maximum of the exothermic curves depended on the given cure temperature and time. To remove $H_2O$ and volatile components, the uncured resin needed a heat-treatment at $100^{\circ}C$ for 60 min at least prior to cure or molding. Curing at $130^{\circ}C$ for 120 min made the exothermic peak of waterborne phenol-formaldehyde resin completely disappeared. And, post-curing at $180^{\circ}C$ for 60 min further improved the thermal stability of the cured resin.

• Journal of Adhesion and Interface
• /
• v.14 no.3
• /
• pp.117-120
• /
• 2013

The prepreg material is a sheet of the reinforcement pre-impregnated with a resin. In this study, two types of prepreg were prepared with a general phenolic resin and the polyvinyl butyral (PVB) modified phenolic resin, respectively, with resin content of 40 wt%. After resin impregnation, the prepregs were heat treated in an oven to make them the B-stage. Surface morphology of the prepreg was observed by using a scanning electron microscope (SEM). Tack property of the prepreg is one of the major properties that govern the ability of prepreg to be laid up. In this study, the tack of prepreg was measured under various test parameters by a probe tact test. Test parameters were contact time, contact force and debonding rate. Most of the tack properties of the prepreg increased with the test parameters. Then tack properties exhibited a linear behavior with test parameters before a saturation point. Also, the tack of prepreg was investigated in relation with the fibrillation phenomena involved in the prepreg surface with the debonding rate.

• Journal of the Korea Concrete Institute
• /
• v.22 no.2
• /
• pp.149-158
• /
• 2010

Recently, numerous construction techniques for repairing and strengthening methods for above ground or air exposed concrete structure have been developed. However repairing and strengthening methods for underwater structural members under continuous loading, such as piers and steel piles need the further development. Therefore, this study develops an aqua epoxy, which can be used for repairing and strengthening of structural members located underwater. Moreover, using the epoxy material and strengthening fibers, a fiber reinforced composite sheet called Aqua Advanced FRP (AAF) for underwater usage is developed. To verify and to obtain properties of the material and the performance of AAF, several tests such as pull-off strength test, bond shear strength test, and chemical resistance test, were carried out. The results showed that the developed aqua epoxy does not easily dissolve in wet conditions and does not create any residual particle during hardening. In spite of underwater conditions, it showed the superior workability, because of the high viscosity over 30,000 cps and adhesion capacity over 2 MPa, which are nearly equivalent to those used in dry conditions. In case of the chemical resistance test, the developed aqua epoxy and composite showed the weight change of about 0.5~1.0%, which verifies the superior chemical resistance.

• Archives of Plastic Surgery
• /
• v.36 no.4
• /
• pp.432-436
• /
• 2009

Purpose: Negative pressure therapy has been used in various conditions to promote wound healing. It has also been used to secure a skin graft by improving microcirculation and improving tight adhesion between the graft and the recipient bed. To reduce post burn scar contracture and improve aesthetical result, many types of dermal substitutes have been invented and used widely. The goal of this study was evaluate usefulness of the VAC (Kinetic concepts Inc., San Antonio, TX) in improving the take rate and time to incorporation of Integra$^{(R)}$ in reconstruction of burn scar contracture. Methods: A retrospective study was performed from October, 2006 to December, 2008. The VAC was utilized for 11 patients. The average patient's age was 19.7 years (range 5 - 27) and average surface area was $785cm^2$ (range 24 - 1600). The burn scars were excised deep into normal subcutaneous tissue to achieve complete release of the scar, Integra$^{(R)}$ was sutured in place with skin staple와 Steri - strip$^{(R)}$. Then slit incisions were made on silicone sheet only with No.11 blade for effective drainage. The VAC was used as a bolster dressing over Integra$^{(R)}$. Negative - Pressure ranging from 100 to 125 mm Hg was applied to black polyurethane foam sponge trimmed to the appropriate wound size. An occlusive seal over the black polyurethane foam sponge was maintained by a combination of the occlusive dressing, OP - site$^{(R)}$. The VAC dressing changes were performed every 3 or 4 days until adequate incorporation was obtained. The neodermis appeared slightly yellow to orange color. When the Integra$^{(R)}$ deemed clinically incorporated, The VAC was removed and take was estimated with visual inspection. Very thin STSG(0.006 ~ 0.008 inches) was performed after silicone sheet removal. Result: The mean time for clinically assessed incorporation of Integra$^{(R)}$ was 10.00 days (range 9 - 12). The mean dressing change was 3.5 times until take was obtained. In All patients, Integra$^{(R)}$ had successful incorporation in tissue without serious complications. Conclusion: Integra$^{(R)}$ in combination with Vacuum - Assisted Closure(VAC) may be incorporated earlier than conventional dressing method.

• Corrosion Science and Technology
• /
• v.12 no.1
• /
• pp.27-33
• /
• 2013

According to its merits about high curing speed and low emission of volatile organic compounds, UV curable inorganic-organic coating technology has been developed as an alternative for toxic and carcinogenic chromate-based treatments for years. It is consistently observed that ultra-thin films offer excellent corrosion protection as well as paint adhesion to metals. Based on the tetra-ethylorthosilicate(TEOS) and methacryloxypropyl trimethoxysilane(MPTMS), inorganic sol was synthesized and formed hybrid networks with UV curable acrylic monomer, 6-hexanediol diacrylate(HDDA), trimethylolpropane triacrylate(TMPTA), pentaerylthritol triacrylate(PETA). Several methods were used to test their properties such as salt spray test, potentiodynamic measurement, tape peel test, etc. It was shown that anti-corrosive property and stability of storage were affected by the molecular ratios of inorganic and organic compounds. It was not only the stability of storage, but had a excellent anti-corrosive, paint adhesive, and anti-solvent properties in a final molar ratios of 0.6/0.04/0.86/0.005 (TEOS/MPTMS/Acetone/HNO3) and 0.08/0.106/0.081/0.02 (TMPTA/HDDA/PETA/photo initiator).

• Current Photovoltaic Research
• /
• v.2 no.1
• /
• pp.14-17
• /
• 2014

In this paper, indium reduced materials for transparent conductive electrodes (TCE) were fabricated and their physical properties were evaluated. Two of materials, indium-zinc-tin oxide (IZTO) and aluminum (Al) were selected as TCE materials. In case of IZTO nanoparticles, composition ratios of In, Zn and Sn is 8:1:1 were synthesized. Size of the synthesized IZTO nanoparticles were less than 10 nm, and specific surface areas were about $90m^2/g$ indicating particle sizes are very fine. Also, the IZTO nanoparticles were well crystallized with (222) preferred orientation despite it was synthesized at the lowered temperature of $300^{\circ}C$. Composition ratios of In, Zn and Sn were very uniform in accordance with those as designed. Meanwhile, Al was deposited onto glass by sputtering in a vacuum chamber for mesh architecture. The Al was well deposited onto the glass, and no pore was observed from the Al surface. The sheet resistance of Al on glass was about $0.3{\Omega}/{\square}$ with small deviation of $0.025{\Omega}/{\square}$, and adhesion was good on the glass substrate since no pelt-off part of Al was observed by tape test. If the Al mesh is combined with ink coated layer which is consistent of IZTO nanoparticles, it is expected that the good and reliable metal mesh architecture for TCE will be formed.

• Journal of Sensor Science and Technology
• /
• v.9 no.3
• /
• pp.171-176
• /
• 2000

The physical and electrical characteristics of MgO and Pt thin-films on it, deposited by reactive sputtering and rf magnetron sputtering, respectively, were analyzed with annealing temperature and time by four-point probe, SEM and XRD. Under annealing conditions of $1000^{\circ}C$ and 2 hr, MgO thin-film had the properties of improving Pt adhesion to $SiO_2$ and insulation without chemical reaction to Pt thin-film, and the sheet resistivity and the resistivity of Pt thin-film deposited on it were $0.1288\;{\Omega}/{\square}$ and $12.88\;{\mu}{\Omega}{\cdot}cm$, respectively. We made Pt resistance pattern on $SiO_2$/Si substrate by lift-off method and fabricated thin-film type Pt-RTD(resistance thermometer device) for micro thermal sensors by Pt-wire, Pt-paste and SOG(spin-on-glass). In the temperature range of $25{\sim}400^{\circ}C$, the TCR value of fabricated Pt-RTD with thickness of $1.0{\mu}m$ was $3927\;ppm/^{\circ}C$ close to the Pt bulk value. Resistance values were varied linearly within the range of measurement temperature.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.12
• /
• pp.185-194
• /
• 2000

Rapid Prototyping(RP) techniques have their unique characteristics according to the working principles: stair-stepped surface of parts due to layer-by-layer stacking, low build speed caused by line-by-line solidification to build one layer, and additional post processing to improve surface roughness, so it is required very high cost to introduce and to maintain of RP apparatus. The objective of this study is to develop a new RP process, Variable Lamination Manufacturing using linear hotwire cutting technique and expandable polystyrene foam sheet as part material(VLM-S), and to investigate characteristics of part material, cutting characteristics by using linear hotwire cutting system and bonding. Experiments were carried out to investigate mechanical properties of part material such as anisotropy and directional tensile strength. In order to obtain optimal dimensional accuracy, surface roughness, and reduced cutting time, addition experiments were performed to find the relationship between cutting speed and cutting offset of hotwire, and heat generation of hotwire per unit length. So, adhesion strength tests according to ASTM test procedure showed that delamination did not occur at bonded area. Based on the data, a clover-shape was fabricated using unit shape part(USP) it is generated hotwire cutting. The results of present study have been reflected on the enhancement of the VLM-S process and apparatus.