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잠열 저장 시스템의 종횡비가 큰 타원형 내부 실린더에 설치된 핀의 위치 변화에 따른 용융 성능에 대한 수치적 연구
박신영(Shin Yeong Park),박성현(Seong Hyun Park),박용갑(Yong Gap Park),하만영(Man Yeong Ha) 대한기계학회 2020 大韓機械學會論文集B Vol.44 No.12
본 연구에서는 핀이 적용된 타원형 내부 실린더가 잠열 저장 시스템의 용융 성능에 미치는 영향을 연구하기 위해 수치 해석을 수행하였다. 상변화 물질의 상변화 과정은 enthalpy-porosity method를 이용하여 모사하였다. 핀 위치 변화에 따른 용융 특성 변화를 살펴보기 위해 타원형 내부 실린더의 표면을 따라 핀의 위치를 변경하였다. 잠열 저장 시스템의 용융 특성을 분석하기 위해 액상 분율, 온도 분포, 속도 벡터를 비교 분석하였다. 핀이 실린더의 상부에 위치할수록 자연 대류의 영향이 감소되어, 잠열 저장 시스템의 성능이 감소되는 경향을 보였다. 핀의 실린더의 하부에 위치할수록 자연 대류의 영향이 증가되어 잠열 저장 시스템의 성능이 향상되는 경향을 보였다. In this paper, the effect of a finned elliptical inner cylinder on the melting performance of a latent heat storage system is presented. The enthalpy–porosity model is used to investigate the phase change process of a phase change material. The fin position is changed along the surface of an elliptical cylinder, and the change in the melting characteristics is examined based on the change in the fin position. The distribution of liquid fraction, temperature, and velocity are numerically investigated to analyze the melting process of the latent heat thermal storage system. The effect of natural convection decreases as fins are located at the top of the cylinder. This deteriorates the performance of the latent heat thermal energy storage system. The effect of natural convection increases as fins are located at the bottom of the cylinder, which in turn improves the performance of the latent heat thermal energy storage system.
핀이 적용된 타원형 내부 실린더가 잠열저장시스템의 용융 성능에 미치는 영향에 대한 수치적 연구
박신영(Shin Yeong Park),박성현(Seong Hyun Park),박용갑(Yong Gap Park),하만영(Man Yeong Ha) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11
This paper presents the effect of a finned elliptical inner cylinder on the melting performance of latent heat storage system. Enthalpy-porosity model is used to investigate phase change process of phase change material. The fin position is changed along the surface of an elliptical cylinder, in order to improve melting performance. The distribution of liquid fraction, temperature and velocity vector are numerically investigated to analyze melting process. As the fin position changes, the heat transfer characteristics change, which can affect the melting performance significantly.
Park, Seong Hyun,Seo, Yeong Min,Ha, Man Yeong,Park, Yong Gap Elsevier 2018 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.126 No.2
<P><B>Abstract</B></P> <P>This paper numerically investigates the two-dimensional natural convection in a square enclosure with a vertical array of a hot elliptical cylinder and a hot circular cylinder with Rayleigh numbers in the range of <SUP> 10 4 </SUP> ⩽ Ra ⩽ <SUP> 10 6 </SUP> . An immersed boundary method was used to capture the wall boundary of the cylinders. The effects of the position and inclination angle ϕ of the elliptical cylinder were investigated. When the Rayleigh number increases to <I>Ra</I> = 10<SUP>6</SUP>, the numerical solutions reach an unsteady state for all cases of the lower elliptical cylinder and the cases of the upper elliptical cylinder except at ϕ = 90 ° . The transition of the flow regime from unsteady state to steady state depends on the flow direction and the space between the upper cylinder and top wall of the enclosure due to the changes in the inclination angle of the elliptical cylinder. At <I>Ra</I> = 10<SUP>6</SUP> in the case of upper elliptical cylinder at ϕ = 0 ° , the time- and surface-averaged Nusselt numbers for the walls of the enclosure increase by about 1.99% compared to the case of two circular cylinders. The thermal performance and flow stability were influenced by the position and inclination angle of the elliptical cylinder.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Two-dimensional numerical simulations were conducted for the natural convection. </LI> <LI> The Immersed Boundary Method was used, based on the Finite Volume Method. </LI> <LI> The transition of the flow regime was investigated at <I>Ra</I> = 10<SUP>6</SUP> according to <I>ϕ</I>. </LI> <LI> The effects of <I>ϕ</I> on the heat transfer characteristics are highlighted. </LI> </UL> </P>
Park, Sang-Man,Lee, Sung-Gap,Yun, Sang-Eun,Noh, Hyun-Ji,Lee, Young-Hie,Bae, Seon-Gi The Korean Institute of Electrical and Electronic 2006 Transactions on Electrical and Electronic Material Vol.7 No.6
[ $Pb(Zr_{0.4}Ti_{0.6}O_{3}\;and\;Pb(Zr_{0.6}Ti_{0.4})O_{3}$ ] paste were made and alternately screen-printed on the $Al_{2}O_{3}$ substrates. We have introduced a press-treatment to obtain a good densification of screen printed films. The porosity of the thick films was decreased with increasing the applied pressure and the thick films pressed at 60 MPa showed the dense microstructure and thickness of about $76\;{\mu}m$. The remanent polarization and coercive field increased with increasing applied pressure and the values for the PZT thick films pressed at 60 MPa were $17.04{\mu}C/cm^{2}$ and 78.09 kV/cm, respectively.
Park, Seong Hyun,Kim, Yang Ho,Kim, Young Soo,Park, Yong Gap,Ha, Man Yeong Elsevier 2018 Applied thermal engineering Vol.137 No.-
<P><B>Abstract</B></P> <P>This paper discusses the effect of the hole location in the fan case on the thermal performance of a gas oven range. A computational fluid dynamics (CFD) study was carried out in ANSYS FLUENT. A DO model was used to include the effect of thermal radiation in the oven cavity. A test geometry was developed by referencing a real product, including the oven cavity, external walls, fan cases, fans, and burners. The simulation was validated with experimental data and showed that the maximum difference in temperature is 2.5%, while the difference in average temperature is 0.44%. A total of 15 cases were examined using different hole locations in the fan case. The direction of the velocity vector at the holes was changed by the different hole locations, and the flow pattern and temperature distribution inside the oven cavity also changed dramatically as a result. The thermal performance was evaluated based on the average temperature and temperature uniformity inside the oven cavity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A numerical study of a gas oven range was carried out using an actual 3D geometry and ANSYS FLUENT. </LI> <LI> A test geometry was developed by referencing a real product. </LI> <LI> The flow pattern and temperature distribution inside the oven cavity changed dramatically. </LI> <LI> Thermal performance was evaluated based on the average temperature and temperature uniformity. </LI> </UL> </P>
Park, Chan Woo,Moon, Yu Gyeong,Seong, Hyejeong,Jung, Soon Won,Oh, Ji-Young,Na, Bock Soon,Park, Nae-Man,Lee, Sang Seok,Im, Sung Gap,Koo, Jae Bon American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.24
<P>We demonstrate a new patterning technique for gallium-based liquid metals on flat substrates, which can provide both high pattern resolution (similar to 20 mu m) and alignment precision as required for highly integrated circuits. In a very similar manner as in the patterning of solid metal films by photolithography and lift-off processes, the liquid metal layer painted over the whole substrate area can be selectively removed by dissolving the underlying photoresist layer, leaving behind robust liquid patterns as defined by the photolithography. This quick and simple method makes it possible to integrate fine-scale interconnects with preformed devices precisely, which is indispensable for realizing monolithically integrated stretchable circuits. As a way for constructing stretchable integrated circuits, we propose a hybrid configuration composed of rigid device regions and liquid interconnects, which is constructed on a rigid substrate first but highly stretchable after being transferred onto an elastomeric substrate. This new method can be useful in various applications requiring both high-resolution and precisely aligned patterning of gallium-based liquid metals.</P>
縮尺模型에 의한 住居空間計劃의 實習 및 示範敎具 開發에 關한 硏究
朴萬植,李昌甲,延吉煥,崔武革 충남대학교 공업교육연구소 1980 論文集 Vol.3 No.1
The design process by scientific method is so complex that it may be effective to divide the activities of the design process into only three-step process; analysis, synthesis and presentation. And the design method by the reduced scale model was evaluated to be effective as it brings about three dimensional emotion of space. The housing space consists of functional space and psychological space on which physical and psychological life are reflected. In order to apply the reduced scale model to the new design process, data on ready-made furnitures and sanitaries in Korea have been collected in terms of size and shape and simplified to standard type. The reduced scale model has been produced on the basis of the standard type, and the education on the housing planning by the reduced scale model has been successfully applied in the undergraduate classes and in-service teacher training courses. With the housing planning process and the guide for the housing planning by the reduced scale model established in this study, the case studies were concluded to be effective and reasonable owing to the following reasons; free planning and modification, inducing interests, time saving, effective co-ordination of group ideas, etc. It is desired to study further on variety and accuracy of the reduced scale model, and recommended to provide the reduced scale model and the planning guide book for the regular teaching material throughout the country.