이 연구에서는 정사각 단면을 갖는 덕트 내부에 원심력의 영향을 받는 유동의 천이특성을 실험 및 수치적으로 규명하였다. 실험적 연구로서 레이저도플러 속도계를 이용하여 축방향속도를 측정하였고, 상용소프트웨어인 플루언트를 이용한 전산유체 시뮬레이션으로 천이특성을 고찰하였다. 유동의 발달은 딘수와 굽힘각에 의존한다는 사실을 알 수 있었으며 덕트의 중앙에서의 속도분포는 원심력 때문에 내외벽보다 낮은 값을 나타내었다.

Waste concrete powder generated during the process of recycling waste concrete into aggregate has a low recycling rate. This is because fine particles of waste concrete powder and cement components are present. Therefore, in this study, waste concrete powder is used as a raw material for centrifugal concrete. Experimental results show that waste concrete powder has cement and aggregate composition, SEM image has irregular shape, C-S-H and Ettringite exist inside. Waste concrete powder showed the same strength, up to 5% in terms of strength by age according to the substitution rate. Also, as the strength characteristics varied according to the centrifugal forming force, the substitution rate of siliceous matter increased by 5% and the strength decreased by substitution rate of 5%. Because of this study, it is considered difficult to use waste concrete powder as a substitute for silica sand because of the resulting characteristics of centrifugal concrete. It is recommended that economic and environmental concerns be considered when some substitution is made for silica sand.

This study is performed structural analysis by boundary condition of pile head. At result, proposed reinforcement length and calculation formula in Super Pretensioned and Reinforced Spun High Strength Concrete Pile

The main purpose of this study was to investigate the characteristics of cylindrical electrostatic precipitator with centrifugal effect in viewpoints of pressure drop and collection efficiency, experimentally. The experiment was carried out for the analysis of current-voltage, pressure drop and collection efficiency with various experimental parameters such as the applied voltage, inlet velocity, inlet size and inlet type(upper and bottom), etc. In the results, the pressure drops were estimated as 27∼54, 34∼63㎜H2O for inlet size 15㎜×3O㎜ and 30㎜×60㎜, respectively. The collection efficiencies were shown over 99% with the small inlet size(15㎜×30㎜) for the applied voltage 40㎸, inlet velocity(15∼21m/s), and 51∼89% with the large inlet size(30㎜×60㎜). Moreover, in the applied voltage 0㎸ and inlet size 15㎜×30㎜, the collection efficiency induced by centrifugal force was represented as about 35% with inlet velocity 15∼21m/s.

There are two different assertions on the rolling error in the solid-controlled gyro compass which contains two rotors in its inner gyro sphere. One assertion is that there is a rolling error and the other is that there is no rolling error. This paper examines the rolling error caused by the centrifugal force by the experiment to reveal that the first assertionis reasonable, and it also attempts to explain qualitatively how the rolling error occurs. The Hokushin-Plath gyro compass is chosen as a model. The rolling error is examined by the swing test in various periods. From the tests, the following results are obtained. As long as the swing is continued under the fixed condition of the ship's heading, the swinging period and the amplitude, no error appears. In case the gyro compass is affected by the swingings except those of the cardinal planes, the error starts to appear only after the swing is finished and it is increasing slowly. It takes about 20 minutes for the error to reach its maximum value. The type of this error is a quadrantal one which makes the ship's heading high in the first and third quarters and low in the second and fourth quarters. But in each case the experimental maximum error is greater than the theorectical one.