In order to analyze the pressure drop of the fluid passing through the hydraulic coupler, a flow model using the Computational Fluid Dynamics (CFD) analysis technique was developed and the fluid flow rate and pressure distribution inside the coupler were analyzed. The analysis model was corrected by comparing the pressure drop measurement using a 6.35mm hydraulic coupler with the ISO reference value and the simulation prediction value. Using the calibrated model, the flow rate and pressure drop of 13 types of hydraulic couplers distributed on the market were analyzed, and their performance was determined by comparing them with ISO reference values. In the case of type A coupler, the pressure drop was generally higher than the ISO reference value, and in the case of type B coupler, the pressure drop was similar to or lower than the ISO reference value. It was confirmed that the complex flow analysis inside the hydraulic coupler could be easily performed through computational fluid dynamics (CFD) modeling, and based on this, problems could be identified and performance could be improved performance.

A 2D axisymmetric numerical analysis was performed to study the characteristics of charge process inside solar thermal storage tank. The porosity and heat transfer coefficient of filler material as well as inlet velocity of heat transfer fluid are selected as simulation parameters. The porosity is varied as 0.2, 0.5, and 0.8 to account for the effect of filler granule geometry. Two levels of the heat transfer coefficient is adopted to assess the heat transfer between heat transfer fluid and filler material. The inlet velocity is varied as 0.00278, 0.0278, and 0.278m/s. As both of the porosity and the heat transfer coefficient increase, the discrepancy of the temperature distributions between the filler and heat transfer fluid decreases. As the inlet velocity increases, the penetration depth of the heat transfer fluid increases proportionally.

HRP(high rate pond) which had kept the manufactured clay of 3㎝-thickness as benthic clay in reactor and the 6 flat-blade turbine as impeller for agitation was named HRASP(high rate algae stabilization pond). And the experiment for treatment of artificial synthesis wastewater containing COD : 300㎎/ℓ. , NH3-N : 30㎎/ℓ, T-P : 9㎎/ℓ. as nutrients was been performed successfully. This reactor was been operated under conditions : 24 hrs.-irradiation and water temperature, 25℃ and pH 7 and agitation velocity, 15, 30, 45rpm and the effect of agitation velocity on algal bioaccumulation of nutrients was been studied with view point of fluid dynamics. The next followings could be obtained as results. 1. The agitation with a turbine impeller blade in HRASP makes clay particle indicate superior suspension effect by means of forming of excellent curl/shear flow in reactor. 2. The excessive suspension of clay particle which is created at 45rpm as rotation velocity of impeller blade of turbine disturbs the light penetration and algal photosynthesis reaction. 3. Efficiencies for removal of nutrients come out as COD : 93.9%∼94.3%, (NH3-N + NO3-N) : 81.9%-99.0%, T-P : 46.8%-53.6%. 4. Kuo values of K1 for algal growth come out seperately as 15rpm : 1.876×10-2, 30rpm : 4.618×10-3. 5. Kuo values of K2 for removal of N, P come out seperately as 15rpm : 8.403×10-1 and 1.397×10-1, 30rpm : 4.823×10-1 and 2.052×10-1. 6. It can be guessed easily that the excessive agitation can inhibit the algal and bacterial symbiotic reaction if it is considered that micro organism' sense to preservation of life is relied on natural function of metabolism. Therefore the studies for this matter should be followed continuously.