• The Research Journal of the Costume Culture
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• v.15 no.3 s.68
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• pp.525-540
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• 2007

This study intended to construct the brand switching matrix in the Korean casual wear market and to analyze it in various aspects. 1,014 sample data were collected in Seoul area, a center of fashion retailing. Since the respondents cited over 200 brand names as their last 2 purchased casual wear brands, 15 most frequently-purchased brands were selected for constructing the brand switching matrix. As a result of the examination, it was founded that the brand loyalty was dominant rather than brand switching in the casual wear market. Polo was identified as the leading brand in the market. Its brand equity, which was comprised of brand recognition, brand preference (loyalty), perceived quality, and brand association, was evaluated very high. Especially, the strength of Polo was the consumer's strong preference and the brand image of simplicity, naturalness, and neatness. After combining 15 brands into 6 groups based on the style and price, additional interpretation was performed on this 'trend switching matrix.' A transition of fashion trend in casual wear was observed. Applying the brand switching matrix on fashion products gave us much insight to the market.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.38.1-38.1
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• 2010

Nanofibers have a large potential in air filtration applications. In this work, we have developed a photocatalytic polyvinyl alcohol PVA/$TiO_2$ nanofibers membrane for the treatment of air filtration by using electrospinning method. PVA were electrospun into nanofibrous membranes and $TiO_2$ nanoparticles were loaded in PVA nanofibers in various contents from 10% (w/w) to 50% (w/w). The UV-Vis spectra were conducted for testing the existence of $TiO_2$ nanoparticles in PVA fibers. SEM analysis indicated that $TiO_2$ nanoparticles were loaded on the surface of PVA fibers and dispersed linearly along the fiber direction, which originated from the effect of polarization and orientation caused by high electric field. X-ray diffraction (XRD) was used to determine the crystalline of the membrane. Tensile strength was measured to evaluate the physical properties of the membrane. Therefore, our work suggested that PVA/$TiO_2$ nanofiber membrane has a potential application in air filtration area.

• Journal of the Korea Fashion and Costume Design Association
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• v.17 no.2
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• pp.125-143
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• 2015

This study has investigated the status of utilizing 3D printing in fashion field in order to keep up with the trend for 3D printing technology to be realized in all industries so that the materials and the modeling modes may be figured out. The following is the findings. The materials used most in 3D printing in fashion field are PA, PLA, TPU, multi-material, ABS and metal. PA, TPU and Multi-material have so much excellent flexibility and strength that they are widely used for garment, shoes and such fashion items as bags. But PLA, ABS and metal are scarcely used for garment because PLA is easily biodegradable in the air, ABS generates harmful gas in the process of manufacture and metal is not flexible, while all of these three are partly used for shoes and accessories. The modeling modes mainly applied for 3D printing in fashion field are SLS, SLA, FDM and Polyjet. SLS, which is of a powder-spraying method, is used for making 3D textile seen just like knitting. Polyjet method, which has higher accuracy and excellent flexibility, can be used for expressing diverse colors, and accordingly it is used a lot for high-quality garment, while SLA and FDM method are found to be mostly used for manufacturing shoes and accessories rather than for making garment because they are easily shrunk to result in deformation.

• Transactions of Materials Processing
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• v.8 no.3
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• pp.259-259
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• 1999

TiC ceramic particulate-reinforced titanium matrix composites were fabricated and the resultant densification, microstructure, and static and dynamic mechanical properties were studied. Comparing Ti with TiH₂powders as host materials for TiC ceramic reinforcement by pressureless vacuum sintering, TiH₂-started composites showed better sinterability and resistance to both elastic and plastic deformation than Ti-started ones. When TiH₂and TiH₂-45 vol.%TiC samples were hot pressed, TiH₂matrices transformed to alpha prime Ti and alpha Ti phase, respectively. It is interpreted that the diffusion of an alpha stabilizer carbon from TiC into the matrix is one of the plausible reasons far such a microstructural difference. The 0.2% offset yield strengths of the hot pressed TiH₂and TiH₂-45 vol.%TiC samples were 1008 and 1446 MPa, respectively, in a static compressive mode (strain rate of 1×$10^{-3}$/s). Dynamic compressive strengths of the samples were 1600 and 2060 MPa, respectively, at a strain rate of 4×10³/s.

• Transactions of Materials Processing
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• v.17 no.1
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• pp.13-18
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• 2008

Mg and Mg alloys are promising materials for light weight high strength applications. In this paper, grain refinement of pure Mg using severe plastic deformation was tried to enhance the mechanical properties of the hard-to-deform metallic material. The microstructure and the mechanical properties of Mg processed by equal channel angular pressing(ECAP) at various processing temperatures were investigated experimentally. ECAP with channel angle of $90^{\circ}$ and corner angle of $0^{\circ}$ was successful at $300^{\circ}C$ without fracture of the samples during the processing. The hardness of the ECAP processed Mg decreased with increasing ECAP processing temperature. The effect of temperature on the hardness and microstructure of the ECAP processed Mg were explained by the dislocation glide in the basal plane and non-basal slip systems and by the dynamic recrystallization and recovery.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.103.1-103.1
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• 2012

본 연구는 차량경량화를 위하여 높은 인장강도와 우수한 인성을 가지는 590MPa급 이상조직강(Dual phase steel)을 이용하여 1991년 TWI(The Welding Institute)에서 개발된 마찰교반접합을 적용하여 접합을 실시하였다. 접합의 공정조건으로 툴의 회전속도는 250~350 RPM, 접합속도로는 50~350 mm/min로 겹치기접합을 실시하였다. 접합에서 사용된 툴은 Megastir에서 제작한 고융점마찰교반접합용 툴인 PCBN(Q-60)을 이용하였고 연구에 사용된 DP590은 포스코(POSCO)에서 제작된 1.4t(mm) 두께인 AHSS(advanced high strength steels)을 사용하였다. 모재인 DP590과 접합체의 미세조직은 광학현미경과 주사전자현미경을 이용하여 관찰하였으며 기계적 특성은 경도시험과 인장시험을 실시하여 조사하였다. 경도의 분포는 모재에서 약 220~230Hv이며 TMAZ부분에서 상승하기 시작하여 접합부에서 약 320Hv까지 상승하는 경향을 보였으며 인장시험 결과 접합속도 100~200 mm/min에서는 모든 시편이 모재에서 파단되어지는 것을 확인할 수 있었다. 위와 같은 결과 300~350 RPM, 100~200 mm/min의 공정조건에서는 접합이 성공적으로 이루어졌으며 차량경량화에 적용이 가능하다고 판단되어진다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.8
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• pp.516-521
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• 2016

Mo-Cu alloys have been widely used for heat sink materials, vacuum technology, automobile, and many other applications due to their excellent physical and electric properties. Especially, Mo-Cu composites with 5 ~ 20 wt.% copper are widely used for the heavy duty service contacts due to their excellent properties like low coefficient of thermal expansion, wear resistance, high temperature strength, and prominent electrical and thermal conductivity. In most of the applications, highly-dense Mo-Cu materials with homogeneous microstructure are required for better performance. In this study, Mo-Cu alloys were prepared by PBM (planetary ball milling) and SPS (spark plasma sintering). The effect of Cu with contents of 5~20 wt.% on the microstructure and thermal properties of Mo-Cu alloys was investigated.

• Journal of Magnetics
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• v.9 no.4
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• pp.105-108
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• 2004

The attempt for the addition of double-phase nanocomposite $Nd_2Fe_{14}BFe_3B$ powders, respectively, into several $RE_2Fe_{14}B$(RE=Pr, Nd) powders with high magnetic properties was carried out. The powders were compounded and compressed to take shape bonded magnets. By means of investigating the variation of compound magnet $B_r$, the interaction between magnetic powders was revealed. The result shows that not chemical just but physical interaction exists between elements. The compound effect of $Nd_2Fe_{14}BFe_3B$-ferrite bonded magnets was detailed studied. The functional relation was revealed between magnetic properties and ferrite content. That is $Y = 5.42 x^2 -11.34x + 6.62$. The variation of $_iH_c$ temperature coefficient ${\beta}_{iHc}$ with ferrite content was investigated. Following the ferrite content increased, ${\beta}_{iHc}$ and $h_{irr}$ were obviously decreased, compression-resistant strength was enhanced.

• Steel and Composite Structures
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• v.19 no.3
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• pp.661-678
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• 2015

Buckling Restrained Braces (BRB) have been widely used in the construction industry as they utilize the most desirable properties of both constituent materials, i.e., steel and concrete. They present excellent structural qualities such as high load bearing capacity, ductility, energy-absorption capability and good structural fire behaviour. The effects of size and type of filler material in the existed gap at the steel core-concrete interface as well as the element's cross sectional shape, on BRB's fire resistance capacity was investigated in this paper. A nonlinear sequentially-coupled thermal-stress three-dimensional model was presented and validated by experimental results. Variation of the samples was described by three groups containing, the steel cores with the same cross section areas and equal yield strength but different materials (metal and concrete) and sizes for the gap. Responses in terms of temperature distribution, critical temperature, heating elapsed time and contraction level of BRB element were examined. The study showed that the superior fire performance of BRB was obtained by altering the filler material in the gap from metal to concrete as well as by increasing the size of the gap. Also, cylindrical BRB performed better under fire conditions compared to the rectangular cross section.

• Corrosion Science and Technology
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• v.7 no.5
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• pp.243-251
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• 2008

Magnesium alloys become popular research topic in last decade due to its light weight and relatively high strength-to-weight ratio in the energy aspiration age. Almost all structure materials are supposed to suspend stress. Magnesium is quite sensitive to corrosive environment, and also sensitive to environmental assisted cracking. However, so far we have the limited knowledge about the environmental sensitive cracking of magnesium alloys. The corrosion fatigue (CF) test was conducted. Many factors' effects, like grain size, texture, heat treatment, loading frequency, stress ratio, strain rate, chemical composition of environment, pH value, relative humidity were investigated. The results showed that all these factors had obvious influence on the crack initiation and propagation. Especially the dependence of CF life on pH value and frequency is quite different to the other traditional structural metallic materials. In order to interpret the results, the electrochemistry tests by polarization dynamic curve and electrochemical impedance spectroscopy were conducted with and without stress. The corrosion of magnesium alloys was also studied by in-situ observation in environmental scanning electron microscopy (ESEM). The corrosion rate changed with the wetting time during the initial corrosion process. The pre-charging of hydrogen caused crack initiated at $\beta$ phase, and with the increase of wetting time the crack propagated, implying that hydrogen produced by corrosion reaction participated in the process.