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신현준,서정윤,Shin, H.J.,Seo, J.Y. 대한설비공학회 1993 설비공학 논문집 Vol.5 No.3
Thermosyphons are simple devices that can passively transport thermal energy over relatively large distance with little temperature degradation. Especially, the thermosyphon system requires no costly energy input and is completely maintenance free. These attributes permit the use of low grade thermal energy for thermal control of structures including the stabilization of highway foundations. This paper presents the experimental results of the snow melting system in which thermosyphon was utilized to ransfer the earth energy to the pavement to remove snow and ice. The test facility, three earth heated and one unheated test panels, is designed to investigate the variables associated with removing snow and ice from pavement surfaces. The results of these test show that the earth heated panel surface temperature is higher $2{\sim}6^{\circ}C$ than unheated panel when the ambient air temperature is $-7^{\circ}C$. The thermal performance of this earth source thermosyphon system for road heating showed that there was no snow on the heated test panels when the snowfall was 5cm average for the region.
신현준(Hyun Jun Shin),김미나(Mi na Kim),윤용산(Yong San Yoon),신현정(Jennifer H. Shin) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Bone consists of three types of mechanosensitive cells, namely osteoblast, osteocytes, and osteoclast. Osteoblasts and osteoclasts are specialized cells responsible for bone formation and resorption, respectively. Osteoblasts get trapped into bone matrix to form osteocytes. These cells functionally adapt to external physical forces in concert to maintain homeostasis and mechanical integrity of the bone. Especially, osteroblasts playa central role in bone remodeling by regulating neighboring osteoclasts and differentiating themselves into osteocytes. In this research, we employ two different types of physical stimulations, tensile stress (TS) and electric field (EF), on osteoblasts to investigate the effects of these forces on factors influencing bone remodeling. Our results indicate that osteoblasts are responsive to both TS and EF, showing noticeable upregulation of ALP, BSP, osteopontin (OP), OPG as well as downregulation of RANKL. Since high expression of RANKL is known to promote osteoclast activity for accelerated resorption, TS and EF induced downregulation of RANKL and upregulation of ALP, BSP, OP, and OPG will likely to activate bone formation. Furthermore, TS and EF have shown to up-regulate the expression of DMP-1, promoting the differentiation of osteoblast to osteocyte. Our study confirms that proper external stimulation can strengthen bone remodeling process through ostoeblast activation and osteoclast de-activation.
세포 인장 자극기의 개발과 세포 인장 자극을 통한 성체 줄기세포의 골분화 유도
신현준(Hyun Jun Shin),이우택(Woo Teak Lee),박석훈(Suk Hoon Park),이선화(Sun Hwa Lee),박정호(Jung Ho Park),윤용산(Yong San Yoon),신현정(Jennifer H. Shin) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.7
Mechanical stimulation is known to play a vital role on the differentiation of mesenchymal stem cells (MSCs) to pre-osteoblasts. In this research, we developed a tensile cell stimulator, composed of a DC motordriven actuator and LVDT sensor for measuring linear displacement, to study the effects of tensile stress on osteogenic differentiation of MSCs. First, we demonstrated the reliability of this device by showing the uniform strain field in the silicon substrate. Secondly, we investigated the effects of tensile stretching on osteogenic differentiation. We imposed a pre-set cyclic strain at a fixed frequency on cell monolayer cultured on a flexible silicon substrate while varying its amplitude and duration. 60 min of resting period was allowed between 30 min of cyclic stretching and this cycle is repeated up to 7 days. Under the combined stimulation with osteogenic media and mechanical stretching, the osteogenic markers such as alkaline phosphatase (ALP), osterix, and osteopontin began to get expressed as early as 4 days of stimulation, which is much shorter than what is typically required for osteogenic media induced differentiation. Moreover, different markers were induced at different magnitudes of the applied strains. Lastly, for the case of ALP, we observed the antagonistic effects of osteogenic media when combined with mechanical stretching.
신현준(H. J. Shin),양한주(H. J. Yang),오수철(S. C. Ohu) 한국자동차공학회 1982 오토저널 Vol.4 No.3
Heat transfer on packed bed is considered to be important for the effective designs of chemical reaction equipment, air conditioning system, and storage type heat exchanger, etc. Currently studies are being carried out quite actively in this field in order to increase the heat transfer effeciency.<br/> The effect of heat transfer is closely related to materials, shapes, porosities and packing states of packed bed as well as mutual dimensional relations between particles and the container. Investigation shows that heat transfer results appear to be influenced by such parameters as fluid velocity through packed bed, mass flow, and thermal properties. It is noted that viscosity is also considered to be an important factor in this problem.<br/> In this study, effective thermal conductivities on packed bed, effects of thermal conductivity (Ke) and friciton factor (Fk) according to change of porosity ( ε) and Reynolds number (Reh), and pressure loss of the fluid, are experimentally investigated.<br/> Results show that the effective thennal conductivity increases and the friction factor decreases, as against the increase of Reynolds number. But as the increase of porosity increase them both.