• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2008.11a
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• pp.479-482
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• 2008

The purpose of this study is a proposal about the flexibility of the performance category to revitalize the "Housing Performance Grading Indication System". This system consists of 5 main performance parts, 14 performance categories and 20 detailed performance lists. 5 main performance parts are Noise and Acoustics(Light-weight impact sound control, heavy-weight impact sound control, sound control of toilet, sound control of party wall), Long-life(flexibility, remodeling & maintenance, durability), Landscape & Indoor Environment(landscape, formaldehyde control& ventilation, daylighting, thermal environment), Welfare & Barrier-free(playground and community center, welfare space, barrier-free design), Fire Safety(fire safety, safe place, fire-resisting quality). The flexibility of the performance category is conformed to Long-life housing related grading and can realize the Long-life housing in response to resident needs about the space rearrangement. Now, The flexibility of the performance category is limited to the evaluation of the private space, that is, the Skeleton evaluation. This study would suggest alternatives to improve uppermost limits through analyzing 60 examples from January 9th 2009 to October 30th 2008. The flexibility of the performance category is possible to estimate not only the Skeleton evaluation but also the Infill evaluation in response to social changes.

• Advanced Composite Materials
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• v.16 no.4
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• pp.283-298
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• 2007

Environment-friendly composites reinforced with bagasse fiber (BF), a kind of natural fiber as the remains from squeezed sugarcane, were fabricated by injection molding and press molding. As appropriate matrices for injection molding and press molding, polypropylene (PP) and polycaprolactone-cornstarch (PCL-C) were selected, as a typical recyclable resin and biodegradable resin, respectively. The mechanical properties of BF/PP composites were investigated in view of fiber mass fraction and injection molding conditions. And the mechanical properties and the biodegradation of BF/PCL composites were also evaluated. In the case of injection molding, the flexural modulus increased with an increase in fiber mass fraction, and the mechanical properties decreased with an increase in cylinder temperature due to the thermal degradation of BF. The optimum conditions increasing the flexural properties and the impact strength were $90^{\circ}C$ mold temperature, 30 s injection interval, and in the range of 165 to $185^{\circ}C$ cylinder temperature. On the other hand, as to BF/PCL-C fully-green composites, both the flexural properties and the impact strength increased with an increase in fiber mass fraction. It is considered that the BF compressed during preparation could result in the enhancement in mechanical properties. The results of the biodegradability test showed the addition of BF caused the acceleration of weight loss, which increased further with increasing fiber content. This reveals that the addition and the quantities of BF could promote the biodegradation of fully-green composites.

• Journal of Fisheries and Marine Sciences Education
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• v.9 no.2
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• pp.188-197
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• 1997

The fracture toughness of three different kinds of epoxy-matrix composites containing the same volume fraction of reinforcement and the variation of fracture toughness of glass-carbon fiber/epoxy hybrid composites due to the change of test temperature and different glass fiber content were investigated in this study. Glass fiber/epoxy composite provided much higher fracture toughness than that of other composites because of the high strain at failure of glass fiber. Particularly the carbon fiber/epoxy composite exhibited the low fracture toughness caused by the low strain energy absorbing capacity of carbon fiber. And it was found that the strain at failure of reinforcement and interfacial delamination absorbing a significant amount of impact energy played an important role to increase fracture toughness of composites. The fracture toughness of the glass-carbon fiber hybrid composites increased with increasing the glass fiber content and decreased with raising the test temperature. The residual stress arising from the different thermal expansion between the matrix and reinforcement influenced the fracture toughness of composites.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.69-74
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• 2011

In this study, it was prepared for nanofiber with high impact polystyrene(HIPS). HIPS is able to crosslinking after electrospinning with crosslinking agent and it could overcome brittle characteristics of polystyrene(PS). After thermal crosslinking, HIPS nanofiber was sulfonated by sulfuric acid. It was investigated FT-IR, XPS, water uptake, ion exchange capacity(IEC), SEM, and contact angle. According to the result of FT-IR and XPS, it was increased due to introduce the hydrophilic group($SO_3H$) in the HIPS nanofiber. The highest water uptake and IEC were 75.6%, 2.67 meq/ g at 120 min sulfonation time with 7.5 wt% DVB.

• Journal of Welding and Joining
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• v.26 no.6
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• pp.74-80
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• 2008

A finite element modeling approach has been described for the simulation and analysis of the micron-scaled solid particle impact behavior in kinetic spraying process, using an explicit code (ABAQUS 6.7-2). High-strain-rate plastic deformation and interface bonding features of the copper, nickel, aluminum, and titanium were investigated via FEM in conjunction with the Johnson-Cook plasticity model. Different aspects of adiabatic shear instabilities of the materials were characterized as a concept of thermal boost-up zone (TBZ), and also discussed based upon energy balance concept with respect to relative recovery energy (RRE) for the purpose of optimizing the bonding process.

• Textile Coloration and Finishing
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• v.29 no.3
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• pp.131-138
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• 2017

Most of high performance fabrics for the car racing protective clothing have been developed to have thermal resistance, flame retardant property, impact resistance and anti-frictional properties to protect the racer from the crucial accident. In this study, the meta-aramid fabric, which has inherent flame retardant, was coated with nanoparticles of SiC to enhance the impact resistance and anti-friction properties. Uniform coating of the nanoparticles onto the fabrics was obtained by using tape casting method. As the experimental parameters, size and content of the SiC nanoparticle were varied with the coating conditions of the fabric surface. The effects of the nanoparticle coating on the properties of meta-aramid fabric were examined with various instrumental analyses such as SEM, tensile strength and abrasion test.

• Journal of ILASS-Korea
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• v.17 no.3
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• pp.128-133
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• 2012

The present study aims to examine the influence of flame spray distance on the thermal behavior of micro-metal particles and the morphological characteristics of $Ni_{20}Cr$ layers coated on the preheated SCM415 substrates by using the conventional flame spray system. Commercially available nickel-based $Ni_{20}Cr$ particles with a mean diameter of $45{\mu}m$ were used. In addition, CFD simulations using a commercial code (FLUENT ver. 6.3.26) were conducted to estimate temperature and velocity distributions of the continuous and discrete phases before impact on the substrate. From FE-SEM images of coated layers on the substrates, it was observed that as the spray distance decreased, the metal particle morphology showed splash-like patterns and such a short stretch shape, resulting from higher particle momentums and the impact of partially melted particles. Moreover, it was found that the spray distance should be considered as one of important parameters in controlling the porosity and the adhesion strength.

• Korean Journal of Crystallography
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• v.13 no.2
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• pp.57-62
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• 2002

Time-of-flight impact-collision ion scattering spectroscopy (TOF-ICISS) was applied to study the geometrical structure of epitaxially grown TiO layers on a MgO(001) surface. The hetero-epitaxial TiO layer was deposited by thermal evaporation of titanium onto the MgO(001) surface and subsequent exposure to oxygen at 400℃. The well-ordered TiO structure was confirmed with the 1×1 RHEED pattern. TOF-ICISS results revealed that the TiO layer was formed at the on-top sites of the MgO(001) substrate and that the lateral lattice constant of TiO layer was the same as that of the MgO substrate. The surface of the deposited epitaxial TiO layer was smooth without the three dimensional islands.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.6
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• pp.263-268
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• 2014

Eskilson's g-function, a well-known geothermal heat response factor, is widely used for sizing of the ground heat exchangers. Unlike the Eskilson's original model that uses common temperature boundaries for all boreholes and along the borehole height, an analytical-solution-based g-function uses a uniform heat transfer rate over the height with variable heat transfer rates for respective boreholes. To evaluate the impact of such a boundary difference on g-function and the design length, a simple case study was carried out on the cooling-dominant commercial buildings. The results show that the design lengths given by the boundary of uniform heat transfer rates are longer than those given by Eskilson's boundary for all cases tested. The difference in length is more important when the bore field is composed of more boreholes with shorter length of each borehole.

• Korean Journal of Materials Research
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• v.25 no.10
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• pp.531-536
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• 2015

GNPs have several excellent mechanical properties including high strength, a good young's modulus, thermal conductivity, corrosion resistance, electronic shielding, etc. In this study, CF/GNP/Epoxy composites were manufactured using GNP weight ratios of 0.15 wt%, 0.3 wt%, 0.5 wt%, 0.7 wt% and 1 wt%. The composites were manufactured with a mechanical method (3-roll-mill). Tensile, impact and wear tests were performed according to ASTM standards D3039, D256 and D3181, respectively. The results show that the CF/GNP0.3wt%/Epoxy composites have good mechanical properties, e.g., tensile strength and impact and wear resistance. In this study, both carbon fabric and GNPs were used as reinforcements in the composites. The mechanical properties increased and weight loss decreased as the GNP content in the resin films was increased.