• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1773-1777
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• 2010

The Application of UV curing technique for poly (vinyl chloride) (PVC) floor tiles coating has improved the quality of PVC floor. Several formulations were made including acrylated oligomers based on a polyurethane were blended with reactive monomers, photoinitiators and other additives. The used oligomers are commercial aliphatic urethane acrylates. Thin films were prepared on PVC tiles by bar coating with different formulations using UV radiation. The coating resins were characterized by FTIR. The properties of UV-cured films such as gloss and adhesion were examined. The properties of UV-cured films dependent on the influence of composition and processing conditions was studied.

• Journal of the Korean Applied Science and Technology
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• v.33 no.1
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• pp.92-99
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• 2016

Polyurethane resin used to leather coat was synthesized by the addition reaction of PPG and PTMG with different mole ratios. Physical characteristics of the synthesized polyurethane resin were measured by the SEM, FT-IR and the UTM. Increasing mole ratio of PTMG having four methylene groups caused the increase of abrasion resistance and tensile strength. The elongation was decreased. As we measured the solvent(toluene) resistance of poly urethane resin, it was found the there were no effect of PTMG mole ratios on the phyhsical properties of the resin. The viscosity was increased by ratio of PTMG mole ratio.

• Journal of Adhesion and Interface
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• v.5 no.2
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• pp.5-14
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• 2004

Since flexible adhesives are used more and more in structural applications, designers should have a better understanding of its behaviour under various conditions as ultimate load, fatigue load, long-term load and environmental conditions. This paper focuses on long-term load conditions and its effect on flexible adhesives. The creep properties of both PU (PolyUrethane) and SMP (Silyl Modified Polymers) adhesives used for identical applications are considered. To investigate the creep behaviour tests under various conditions were done. The results of those tests are presented and compared. To evaluate these results an empirical method is proposed and discussed. An example illustrates the potential of this method. It is also shown that with use of a probabilistic calibration technique this method results into a simple rule, which can be used to calculate the creep for practical applications. For the studied adhesives, the creep performance of the SMP adhesive is shown to be of the same level or slightly better than of the two PU adhesives. In addition to this empirical method, the principles of a more complex theoretical based method are introduced. The potential of this method is illustrated and future research activities are drawn.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.44.2-44.2
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• 2009

BCP powder was synthesized using microwave hydrothermal process with mixed calcium hydroxide and phosphoric acid. After using replica method, porous BCP scaffold was fabricated. PU (Poly Urethane) was used as the fugitive skeleton to fabricate the porous scaffold. BCP powder was mixed in PVB (Polyvinyl butyral) and ethanol solution and then applied to the PU foam by dip coating. After several times of coating and the subsequent oven drying the coated PU foam was burnt out at $750^{\circ}C$ at air to remove the PU. The resulting networked porous composites were sintered at $1250^{\circ}C$, $1300^{\circ}C$ and $1350^{\circ}C$ in microwave furnace for 30 minutes. Material properties of the porous bodies like compressive strength and porosity were investigated. Detailed microstructure of the BCP porous body was characterized by SEM and XRD and TEM techniques. In our experiments, the relationship between mechanical property and viscosity of powder, sintering temperature was investigated.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.4
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• pp.507-513
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• 2013

Transparent bulletproof windows play an important role in the munitions industry. The thickness of bulletproof windows including soda-lime silicate(SLS) glass, polyvinyl butyral, poly urethane, main defense(200MD), and safety film was reduced from 40mm to 29mm by adjustment of SLS glass laminated array. Borosilicate glasses generally have lower surface density and more excellent mechanical properties than SLS glass. Borosilicate glass was strengthened by ion exchange in the $KNO_3$ powder. The maximum mechanical properties were observed at $550^{\circ}C$ for 10min. The Vickers hardness, fracture toughness and 3-point bending strength of ion exchanged samples were about $775kg/mm^2$, $1.91MPa{\cdot}m^{1/2}$ and 764MPa each, which are about 27%, 149% and 249% higher than parent borosilicate glass, respectively. The penetration depth of K+ ion at $550^{\circ}C$ for 10min was $59.8{\mu}m$. As a result, the transparent bulletproof windows were predicted to be more lightweight by ion exchange of borosilicate glass. If the SLS glass for bulletproof windows is replaced by ion exchanged borosilicate glass, the bulletproof windows can be expected to be lightweight and thinner.

• Microbiology and Biotechnology Letters
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• v.17 no.4
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• pp.343-348
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• 1989

Production of shikonin derivatives by Lithospermum erythrorhizon cells by using polyurethane foam was invesliigated. Shikonin derivatives were effectively adsorbed mostly by phase distribution to polyurethane matrices and their production increased significantly compared to the suspension culture. The enhanced production of shikonin was probably due to more facilitated cell to cell con-tact and lowered intracellular shikonin concentration, both of which are known to be favorable for plant secondary metabolite production. In order to improve the process productivity, tell culture was conducted under various culture conditions: Of them, Schenk and Hildebrandt medium containing indole-3-acetic acid (1.75mg/ι) and kinetin (0.1mg/ι) was considered most appropriate for shikonin production. Production of shikonin increased about 4.5 times in the Schenk and Hildebrandt medium containing indole-3-acetic acid (1.15mg/ι) and kinetin (0.1mg/ι) when compared to the same medium containing p-chlorophenoxyacetic acid (2.0mg/ι) and kinetin (0.1mg/ι). When poly-urethane was used as the support material, a single-stage system was more preferred to the conventional two-stage culture system in terms of shikonin productivity.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.21-32
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• 2002

Small and full scale model tests were performed to obtain the transient responses of shafts subjected to elastic impact by impact-echo test. Four end conditions of drilled shafts were considered: (1) free, (2) fixed, (3) rock-socketed, and (4) soft bottom. In small scale model tests, mock-up shafts were fabricated to simulate these four drilled shafts using poly-urethane and plastic material. Additionally, skin frictions between shaft and rock were changed to find out the effect of side contact on dynamic responses. All impact responses were tested in the air. Subsequently, full scale model tests were also carried out on concrete shafts that were in free and rock-socketed condition. The end conditions of the drilled shafts could be identified with good reliability by the waveforms from both small and full scale model tests. The results obtained in this study will provide an improved understanding of the impact responses for end conditions, especially for rock-socketed drilled shafts that are frequently designed and built in Korea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1078-1084
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• 2011

In design of sport footwear, bending stiffness of its toe part is an important factor though it can be hardly measured. This paper introduces a device for measuring the bending stiffness. The device is simply designed with aluminum frames, one AC motor, two load-cells, one encoder and control hardwares. The mechanism measuring the bending moment of a shoe is described. Then, it was used to observe how the midsole material and design of a sports shoe affect on its bending stiffness. For the experiments, various specimens prepared, where each midsole of the specimens is different in terms of material, thickness and hardness. With those specimens, experiments were performed by using the device and then the bending stiffness was computed by applying the least square curve fitting after the bending moment data were measured. The specimen with Poly-urethane(PU) midsole has the higher bending stiffness than the one with Phylon(PH) midsole, and the midsole thickness affects more on the bending stiffness than the midsole hardness. Based on those results, it can be concluded that the measurement device can provide consistent bending stiffness data to sports footwear and the bending stiffness of a footwear measured by the developed device can be used as a major parameter in the footwear design.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.6
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• pp.675-681
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• 2010

It is well known that mesenchymal stem cell(MSCs) can be differentiated into fibroblasts, chondrocytes, and osteoblasts and that they develop into fibrous tissue, cartilage, or bone, as a result of mechanical stimulation. In this study, we developed a bioreactor system, which is composed of a reactor vessel that provides the required cell culture environment, an environment controlling chamber to control the media, a gas mixer, and a reactor motion control subsystem to apply mechanical stimuli to the cells. For the MSC culture, We used a poly-urethane (PU) scaffold, with a collagen coating to ensure improved cohesion ratio. Then, we transferred the cultivated MSCs in the PU scaffold, cultured the cells in the bioreactor system, and confirmed the proliferation, differentiation, and ossification processes, resulting from mechanical stimuli.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.559-565
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• 2011

The following noble series of statistical copolymers, poly[(2-(3-thienyl)ethanol n-butoxycarbonylmethylurethane)-co-3-hexylthiophene] (PURET-co-P3HT), were synthesized by the chemical dehydrogenation method using anhydrous $FeCl_3$. The structure and electro-optical properties of these copolymers were characterized using $^1H$-NMR, UV-visible spectroscopy, elemental analysis, GPC, DSC, TGA, photoluminescence (PL), and cyclic voltammetry (CV). The statistical copolymers, PURET-co-P3HT (1:0, 2:1, 1:1, 1:2, 1:3), were soluble in common organic solvents and easily spin coated onto indium-tin oxide (ITO) coated glass substrates. Hybrid bulk heterojunction photovoltaic cells with an ITO/G-PEDOT/PURET-co-P3HT:PCBM:Ag nanowires/$TiO_x$/Al configuration were fabricated, and the photovoltaic cells using PURET-co-P3HT (1:2) showed the best photovoltaic performance compared with those using PURET-co-P3HT (1:0, 2:1, 1:1, 1:3). The optimal hybrid bulk heterojunction photovoltaic cell exhibits a power conversion efficiency (PCE) of 1.58% ($V_{oc}$ = 0.82 V, $J_{sc}$ = 5.58, FF = 0.35) with PURET-co-P3HT (1:2) measured by using an AM 1.5 G irradiation (100 mW/$cm^2$) on an Oriel Xenon solar simulator (Oriel 300 W).