Hydrodynamic characteristics such as gas holdup, liquid circulation velocity and bed expansion in a hexagonal inverse fluidized bed were investigated using air-water system by changing the ratio (Ad/Ar) of cross-sectional area between the riser and the downcomer, the liquid level(Hl/H), and the superficial gas velocity(Ug). The gas holdup and the liquid circulation velocity were steadily increased with the superficial gas velocity increasing, but at high superficial gas velocity, some of gas bubbles were carried over to a downcomer and circulated through the column. When the superficial gas velocity was high, the Ad/Ar ratio in the range of 1 to 2.4 did not affect the liquid circulation velocity, but the maximum bed expansion was obtained at Ad/Ar ratio of 1.25. liquid circulation velocity was expressed as a model equation below with variables of the cross-sectional area ratio(Ad/Ar) between riser to downcomer, the liquid level(H1/H), the superficial gas velocity(Ug), the sparger height[(H-Hs)/H], and the draft plate level(Hb/H). Uld=11.62g^0.75(Hl/H)^10.30(Ad/Ar)^-0.52(H-Hs/H)^0.91(Hb/H)^0.13

출발, 정지, 후진, 가속, 감속 등을 포함하는 저속 항행시의 조종운동을 예측하기 위해서, 선체, 프로펠러, 타에 작용하는 유체력의 특징을 검토하여 이를 수식모델화 하였으며, 제안된 수식모델을 이용하여 유조선, 가스운반선 두 선박에 대해 저속시의 조종운동 시뮬레이션 계산을 수행하여 실험결과와 비교 검토하였다