제주 테우의 운동특성에 관한 연구

Abstract

Regarding the structure of Jeju Tawoo, the diameter of the front of log is narrow and that of the back of log has the shape of a longitudinal and the stern is 30-40cm longer than the bow, which has taken account of bow wave. If the stern and bow of a boat have the same length, the boat has the wider area that contact with the wave and the resistance to bow wave increases, which serves as an obstacle to sailing whereas Tawoo with narrow bow has less resistance to the bow wave and thus the safety and comfort during fishing activity increase. To investigate the optimal traverse gap for absorbing wave motion characteristics and the motion characteristics of Tawoo, the reflection coefficient according to the period of porous rate and wave length(), transmission coefficient, energy dissipation coefficient was analyzed conducting a hydraulic model second tank experiment. The results indicated when the wave passes by, the wave pressure increases and thereby the wave packet decreases in the gap of the model, which incurs an eddy; the eddy is absorbed through the gap, resulting in energy dissipation. The reflection coefficient and energy dissipation coefficient have same tendency. They increase as the wave length decreases and as they get near to high frequency area whereas the transmission coefficient increase as the wave length increases and it gets near low-frequency areas. With regard to reflection coefficient, the distribution range of measured data becomes narrow and the mean decreases as the porous rate increases and the distribution range and mean of data decreases particularly at p(porous rate)=0.2518. In the case of transmission coefficient, the distribution range of the data measured around the mean increases and the mean gradually increase as the porous coefficient increases, which is contrary to reflection coefficient. In particular, the data range is the narrowest in the correlation equation at p(porous rate) = 0.2518, yet the mean value is the lowest at p(porous rate) whereas the energy dissipation coefficient linearly increases as the porous rate increases towards the center at p(porous rate) = 0.2518 and then decreases again from the center, indicating wave is absorbed stably as energy dissipation coefficient increases, which leads to better navigability. An increase of energy dissipation coefficient means more wave is absorbed by the porosity of model when waves pass by the experimental model. Thus the results of this experiment to find the best porous rate of 8 experimental models of Tawoo motion characteristics indicated the highest energy dissipation coefficient can be obtained at 0.25 (p(porous rate) = 0.2518). The results of experiment proved the porous rate varies depending on the wave length of incident wave, yet short-wave results in higher energy dissipation coefficient than long-wave and the period and porous rate are in a reverse correlation. The results of Tawoo model experiment suggested the excellent motion characteristics of Tawoo based on the thoughts in marine engineering make Tawoo as an excellent marine transportation means. However these results have been derived from a model tank experiment. Thus to extract more reliable results, it is essential to conduct sea trials on the basis of these results.