In this paper, 50MHz reflection ultrasonic microscope system with small aperture acoustic lens has been constructed in order to study the defects which lay deep in thick specimens, and acoustic images of multilayered media have been analyzed. Output characteristics of this system for multilayered media have been influenced by acoustic attenuation, aberration in specimen, type of lens and the properties of a defect, and it has been used for image processing of the multilayered I.C. and the bonding layer. In experimental results, it has been shown that small aperture ultrasonic microscope system was powerful tool for inspection of thick specimens such as electronic device, bonding layer, quality of ceramic materials.

A Study is made on shrink fit shaft in which its part is modelled and spring stiffness per unit length is estimated, then obtained transfer matrix. Transfer matrix of shaft is found by Myklestad's method and natural frequency is found by shrink fit tolerance on shrink fit shaft, too. In order to verify effectiveness of shrink fit effect, hollow shaft of the same size is compared with shrink fit shaft which will verified on experiment. As a result of this study, the more shrink fit tolerance increases, the more spring stiffness per unit length increases. It is obvious from the above results that shrink fit shaft due to shrink fit tolerances decreases natural frequency.

An ultrasonic power measurement system in milliwatt range was constructed. The ultrasonic power can be determined by measuring the radiation pressure on a target using self-compensating microbalance. Measurement was performed using a perfect reflector and a perfect absorber. In order to check the feasibility of the system, the ultrasonic power for the two targets was measured. Also, the systematic measurement errors and the reproducibility were examined. The relative error between two targets is proved to be within 2%. Also when the ultrasonic power range is larger than 10mW, the standard deviation for repeated measurement becomes smaller than 2%.

The energy parameter is widely used in pre-processing of speech signals, because it represent the phoneme characteristics of well But, the energy parameter is affected by the window length during the extracting. Thus, in this paper, the window length effects are studied in detail, and we proposed a new energy extraction algorithm that reduces the length effects. The energy contours with this algorithm are well representing for the characteristics of speech phonemes. And the computations to implement the algorithm are only required one subtraction, one addition, and two comparison aperation per speech sample.

A method of measuring impulse response of acoustic system, two kinds of cross-correlation methods (the direct correlation method and the M-sequence modulation correlation method) were applied. According to the direct correlation method, by using stationary random noise source and by calculating the cross-correlation function between the sourece and the output signal, equivalent impulse response can be obtained not being influenced by the back ground noises. By applying this method, the measurement of echo-time patterns in rooms and oblique incident sound absorption characteristics of sound absorbing materials was carried out. In the case of the M-sequence modulation correlation method which was contrived by Aoshima, an intermittent random nosie modulated by M-sequence signal is used as the source signal, and the cross-correlation function between the M-sequence signal and the squared output signal is calculated. According to this method, equivalent energy impulse response (squared impulse response) of te propagation system can be obtained without being influenced by the back ground noises and the air fluctuation caused by wind. As the applcaition of this measuring method to the architectural acoustics, the meaurements of echo-time patterns, reverberation decays and sound pressure lev디 distributions in rooms and sound insulation efficiencies in buildings were carried out. From these experimental studies, it has been found that this M-sequence modulation correlation method is markedly useful especially for the field masurement of sound insulation under high back ground noise condition.

MSK waveforms are advantageous from the point of view of reduced interchannel interference. MSK waveform, however, is more difficult to generate than PSK due to its complex pulse shape. A SAW filter is ideally suited for generation of MSK waveform because it provides accurate control of the required impulse responese and linear phase at high frequncies. In this paper, an implementation of SAW based PSK-MSK convert filter, which can easily convert the high frequency PSK waveform to MSK, is studied.

We have investigated the digital bit synchronization problem in baseband communication receiver systems using the Gauss-Markov estimation technique which is equivalent to the weighted least square method. The realized bit synchronizer, including the data detector, processes the input signal two dimensionally into the transition phase and data level under the white Gaussian noise environment. We have confirmed the relization of the bit synchronizer via computer simulation. In addition, we have compared and evaluated the estimation error performance of the proposed method with that of the conventional DTTL method and of the minimum likelihood method.