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수평 및 수직 메조 스케일 Y-자형 합류 지점을 이용한 기체 플러그 생성
조성근(Seong Keun Jo),염수진(Sujin Yeom),이상용(Sang Yong Lee) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
In the present study, the effects of flow direction and channel size on the generated gas plug length at merging Y-junctions were investigated experimentally. Two Y-junctions which have square cross section with their sides being 0.52 and 2.53 ㎜, respectively, were used as test sections. Air and water were injected into the test section in vertical and horizontal directions. Water and air superficial velocities were varied from 0.0012 ㎧ to 0.02 ㎧ and from 0.00052 to 0.3 ㎧, respectively. As a result, the lengths of plugs generated with vertical configuration were shorter than those with horizontal one. Furthermore, the effect of the flow direction on the plug length became significant with larger channel size.
핀-관 열교환기용 분배기에서 유량 분배가 압력손실에 미치는 영향에 대한 실험적 연구
김우식(Woo Shik Kim),조성근(Seong Keun Jo),이상용(Sang Yong Lee) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
In the present study, the effect of flow distribution on pressure loss at distributor for fin-tube heat exchanger was investigated experimentally. Filtered tap water was used as working fluid. The working fluid was flowed into single inlet with 10 ㎜ of inner diameter and distributed to seven axisymmetric outlet ports with 2.5 ㎜ of inner diameter. Inlet flow rate range was from 0.06 to 0.09 ㎏/s and flow distribution ratio, which means flow rate through on outlet tube divided by inlet flow rate, was varied from 0.05 to 0.35. Pressure loss at the distributor was estimated from measured pressure profiles in the inlet and one of the outlet tubes. The value of the loss coefficient calculated from pressure loss decreased with the increase of the both inlet flow rate and flow distribution ratio. Empirical correlation of the loss coefficient was proposed in terms of inlet Reynolds number and the flow distribution ratio.
염기처리시간에 따른 지르코니아 현탁액의 분산성과 굴절율 변화
조충희,함동석,이재흥,류주환,이기윤,조성근,Jo, Choong Hee,Ham, Dong Seok,Lee, Jae Heung,Ryu, Juwhan,Lee, Kee-Yoon,Cho, Seong Keun 한국재료학회 2017 한국재료학회지 Vol.27 No.1
Zirconia nanoparticles were widely used as filler in order to get high refractive index layer. However, dispersion of nanoparticles is difficult due to their agglomeration in solvent. In this study, the dispersibility of the zirconia suspension is promoted by controlling the steric hindrance and electrostatic interactions through the adsorption of PEI according to alkali treatment time. Also, to induce improved dispersibility on suspension, we changed the dispersion conditions variously and fabricated an ink formulation method for the coating layer. Zirconia suspension was characterized by dynamic light scattering (DLS), Zeta potential measurement, Transmission Electron Microscope (TEM) and FT-IR. We were able to confirm that good dispersion of zirconia suspension by alkali treatment and PEI led to high refractive index.