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鋼의 酸洗廢液을 利用한 Mn-ferrite 磁性잉크 製造에 관한 연구
車東德,徐利洙,金營三 동아대학교 공과대학 부설 한국자원개발연구소 1990 硏究報告 Vol.14 No.2
This papper describes the results on formation of Mn-ferrite particles to be used in making magnetic ink from the picking liquor of steel which contain 8.9wt% of Fe ion (in which ㏖ ratio of Fe^(2+)/Fe^(3+)=1) and 1.5-5.0 ㏖ ratio of Fe/Mn^(2+) under conditions of pH 11, temperature of 80℃, air blowing rate of 100cc/sec. 1) Mn-ferrite particles at Fe/Mn^(2+) ㏖ ratio if 1.5-5.0 were of ultra fine sizes less than 180 angstrom. 2) It was possible to produce magnetic ink by coating the oleic and sodium dodecyl benzene sulfonate on the surface of the Mn-ferrite particles made from the waste pickling liquor of steel and dispersing them into water. 3) As the result of filtering from the picking liquor of steel, the residue concentrates of the filterate solution were conformed to be mainly of Cl, Cr^(3+), Cr^(6+), and Zn with their conncentrations of 2690, 0.021, 0.084 and 0.021 ppm respectively. Accorddingly, it may not be a problem as a foul water of urban.
수직평판(垂直平板)에 부착(附着)된 수평(水平)핀에서의 자연대류(自然對流)
김선정,이정철,서리수,권순석,Kim, S.J.,Lee, J.C.,Seo, L.S.,Kwon, S.S. 대한설비공학회 1988 설비저널 Vol.17 No.4
A study has been conducted experimentally on natural convection heat transfer characteristics of a vertical flat plate with horizontal rectangular fins in air. The effects of fin heights and Rayleigh numbers are mainly investigated. The experimental results are as follows; 1. The mean fin, plate and total Nusselt numbers decrease as dimensionless fin heights H/S increase at $0.50{\leq}H/S{\leq}2.00$. 2. The mean fin surface Nusselt number in case of H/S = 0.50 and $Ra_c=4.33{\times}10^3$ shows its maximum at $X_1$, surface where there is no interference with other fins. 3. Owing to the interference of fins the mean plate Nusselt numbers at H/S=0.50 and 2.00 for $Ra_S=6.57{\times}10^3$ are 35% and 80% respectively less than the mean fin Nusselt numbers. 4. The mean fin, plate and total Nusselt numbers of horizontal rectangular fins show higher values at short fins, but lower values at long fins than those of upward vertical fins.
徐龍權(Yong-Kweon Suh),徐利洙(Lee-Su Suh),朴春根(Chun-Kun Park),文琮春(Jong-Chun Moon) 한국해양공학회 1989 韓國海洋工學會誌 Vol.3 No.1
The hydrodynamic forces acting on a circular cylinder oscillating in the water tank were measured. On the other hand, the automatic motor-driven camera was used to visualize the vortex pattern and its development around the cylinder.<br/> It turned out that the modified Morison's equation proposed here is closer than the original Morison's equation to the experimental data.
Vortex Motion near the Edge of a Semi-Infinite Flat Plate Impulsively Started Transversally
Y. K. Suh(徐龍權),L. S. Seo(徐利洙) 한국해양공학회 1988 韓國海洋工學會誌 Vol.2 No.1
정지된 유동장에 놓인 반무한 평판이 橫方向으로 갑자기 출발하는 경우에 있어서 평판의 끝에서 발생하는 보텍스의 거동을 해석적 및 수치적 측면에서 검토하였다. 해석적 방법은 단일 보텍스 모델에 근거를 두었으며, 해석결과 순환량은 시간의 1/3승, 보텍스의 중심까지의 거리는 시간의 2/3승에 비례하여 증가함을 알 수 있었다. 룬게ㆍ쿠타(Runge-Kutta)方法을 써서 분리 보텍스 모델에 따른 비선형 운동방정식의 解를 수치적으로 구했다. 수치해는 시간의 경과에 따라 해석 解에 접근하였다. 보텍스의 형상에 있어서도 실험결과와 잘 맞았다.