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Fabrication of micro-patterned aluminum surfaces for low ice adhesion strength
Jeon, Jaehyeon,Jang, Hanmin,Chang, Jinho,Lee, Kwan-Soo,Kim, Dong Rip Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.440 No.-
<P><B>Abstract</B></P> <P>We report a fabrication method to obtain a low-ice-adhesion aluminum surface by surface texturing using solution etching and subsequent thin-film coating. Specifically, the textured surface has microstructures of a low aspect ratio, that is, with a much smaller height than width. Such microstructures can effectively reduce ice-adhesion strengths by sliding the ice during detachment. Because our method is based on solution etching, it can be applied to curved surfaces with complex shapes for uniformly constructing the morphology of a low-ice-adhesion aluminum surface. Finally, the low-ice-adhesion aluminum surface reduces the ice-adhesion strengths by up to 95%.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Micropatterns with a low aspect ratio were effective to lower ice adhesion on the surface. </LI> <LI> Facile fabrication of low ice-adhesive aluminum surface with the micropatterns of a low aspect ratio was developed. </LI> <LI> The low ice-adhesion aluminum surface reduces the ice-adhesion strengths by up to 95%. </LI> </UL> </P>
Kim, Jaehyeon,Hyun, Younghoon,Park, Youngsam,Choi, Wonchul,Kim, Soojung,Jeon, Hyojin,Zyung, Taehyeong,Jang, Moongyu American Scientific Publishers 2013 Journal of Nanoscience and Nanotechnology Vol.13 No.9
<P>A silicon nanowire one-dimensional thermoelectric device is presented as a solution to enhance thermoelectric performance. A top-down process is adopted for the definition of 50 nm silicon nanowires (SiNWs) and the fabrication of the nano-structured thermoelectric devices on silicon on insulator (SOl) wafer. To measure the Seebeck coefficients of 50 nm width n- and p-type SiNWs, a thermoelectric test structure, containing SiNWs, micro-heaters and temperature sensors is fabricated. Doping concentration is 1.0 x 10(20) cm(-3) for both for n- and p-type SiNWs. To determine the temperature gradient, a temperature coefficient of resistance (TCR) analysis is done and the extracted TCR value is 1750-1800 PPM x K(-1). The measured Seebeck coefficients are -127.583 microV x K(-1) and 141.758 microV x K(-1) for n- and p-type SiNWs, respectively, at room temperature. Consequently, power factor values are 1.46 mW x m(-1) x K(-2) and 1.66 mW x m(-1) x K(-2) for n- and p-type SiNWs, respectively. Our results indicate that SiNWs based thermoelectric devices have a great potential for applications in future energy conversion systems.</P>
플랫폼 비즈니스에서의 승자독식 현상에 영향을 미치는 서비스 특성
전익진(Ikjin Jeon),안재현(JaeHyeon Ahn),김도훈(Dohoon Kim) 한국경영과학회 2016 經營 科學 Vol.33 No.4
The market of platform business is typically served by a few dominant players, presenting “winner-takes-all” phenomenon. This study aims to find service characteristics leading to the phenomenon. Six different servicecharacteristics were considered : Same-side network effect, cross-side network effects, entry barrier, multi-homing cost, switching cost, and heterogeneity of preference. To assess the degree of concentration of market share, HHI (Herfindahl-Hirschman Index) is calculated for top three major players. Based on the HHI value, 10 most eminent platform businesses are classified into three different segments and each segment is characterized with key factors. The results from this study provide some insight into the strategic management of platform business.
Kim, Junghan,Jeon, Jaehyeon,Kim, Dong Rip,Lee, Kwan-Soo Elsevier 2018 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.126 No.2
<P><B>Abstract</B></P> <P>In order to quantitatively analyze the anti-freezing characteristics of superhydrophobic and bare surfaces, the freezing delay properties of the surfaces were experimentally investigated under various operating conditions by placing sessile droplets on their surface. The freezing delay time was calculated using the experimental results and analyzed by employing a stochastic method. The formation time of initial ice nuclei and freezing propagation velocity at a macroscopic level were proposed as measures of surface anti-freezing characteristics. The anti-freezing properties of the bare and superhydrophobic surfaces were analyzed using the proposed quantitative measures. Consequently, the tendency of quantitative results was consistent with that of the qualitative ones according to the changes of the operating conditions (air inlet velocity, relative humidity, and surface temperature). Moreover, the superior anti-freezing performance of the superhydrophobic surface was quantitatively confirmed by the initial ice nuclei formation time, which was delayed by 22–92%, and the freezing propagation velocity, which decreased by 17–30%.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The freezing delay of sessile droplets was experimentally investigated under various operating conditions. </LI> <LI> The initial ice nuclei formation time and freezing propagation velocity were proposed. </LI> <LI> The anti-freezing characteristics of bare and superhydrophobic surfaces were quantitatively studied. </LI> </UL> </P>
Thermal and Catalytic Degradation of Waste High-density Polyethylene (HDPE) Using Spent FCC Catalyst
Lee, Kyong-Hwan,Jeon, Sang-Gu,Kim, Kwang-Ho,Noh, Nam-Sun,Shin, Dae-Hyun,Park, Jaehyeon,Seo, Younghwa,Yee, Jurng-Jae,Kim, Geug-Tae 한국화학공학회 2003 Korean Journal of Chemical Engineering Vol.20 No.4
Thermal and catalytic degradation using spent fluid catalytic cracking (FCC) catalyst of waste high-density polyethylene (HDPE) at 430℃ into fuel oil were carried out with a stirred semi-batch operation. The product yield and the recovery amount, molecular weight distribution and paraffin, olefin, naphthene and aromatic (PONA) distribution of liquid product by catalytic degradation using spent FCC catalyst were compared with those by thermal degradation. The catalytic degradation had lower degradation temperature, faster liquid product rate and more olefin products as well as shorter molecular weight distributions of gasoline range in the liquid product than thermal degradation. These results confirmed that the catalytic degradation using spent FCC catalyst could be a better alternative method to solve a major environmental problem of waste plastics.