Temperature field visualization by using Thermo-paint is performed on hot and cold liquids mixing process encountered in cup-type beverage vending machines. In this experiment, four kinds of Thermo-paint in micro capsule of 10 μm are mixed to response for a wide temperature difference range of 60°C and applied to a cup type vessel contained initially separated hot and cold liquids which is stirred by flat-plate paddles at 900 rpm. The visualized images are recorded by a digital video camera and processed by contrast technique to identity its temperature. As a result, this Thermo-paint technique is found to be attractive to reflect sensibly the temperature filed of hot and cold liquids mixing process with high speed and to analyze the temperature mixing mechanics.

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A data hiding method for multi-band image based on wavelet MRA (Multi-Resolution Analysis) with PCA (Principal Component Analysis) is proposed. The conventional method hides key image only in a single band component of the original multi-band image. The proposed method hides key image in the 1st principal component of the original multi-band image. Due to the fact that a power of the original multi-band image is usually comparable to that of key image, the hidden data are recognizable. The hidden data through the proposed method are not so recognizable, for it is always true that a power of the 1st principal component is greater than that of a single band component of the original multi-band image. It is found that the RMS (Root Mean Square) error of the proposed method is about 40% than that of the conventional method.

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