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의공학적 기법에 의한 간병변의 검진과 치료 경과의 정량 : 초음파 신호처리 Ultrasound Signal Processing
우광방,진영민 연세대학교 대학원 1985 延世論叢 Vol.21 No.4
This study was aimed to develop the technique of signal processing which enables the improvement of the resolution of A-scan in the image of ultrasound sonogram to human organs, including patients with liver disease. The ultrasound was transmitted to the phantom composed of hard rubber(63×60×6mm), glycerin(60×60×13mm) and gluss(60×60×4mm), and the spectral extrapolation algorithm was developed and utilized to improve the resolution of A-scan out of the region of finite frequency band and to find the location as well as the reflection coefficient of the reflector from the image of A-scan. The results from the analysis of ultrasound image by the spectral extrapolation include the following: 1. For the reflected signal containing no noise, the resolution of the A-scan signal was not influenced by the duration of transmitted signal and was limited only by the sampling interval. 2. For the reflected signal containing noise, the location and the reflection coefficient of the reflector with depth of 0.5mm of the phantom were detected when the ultrasound was applied with center frequency of 2.25MHz. 3. When the level of noise in the reflected signal leas reduced, the resolution of the signal was improved so that the depth of the reflector less than 0.5mm was detected. It is expected that this technique will be of considerable value to the analysis of the data obtained from the patients with liver disease.
우광방,김성신 연세대학교 대학원 1986 延世論叢 Vol.22 No.1
In order to speed up tobot motion and to decrease the execution of the given task, the present study designed to propose a method of calaulating a time schedule of positions, velocities, and accelerations along the some specified Cartesian knots in work space that the manipulator may adopt a minimum traveling time under the constraints. Picewise cubic polynomials are used to fit the sequence of joint displacements for each of the N joints. The obtained trajectories are continuous on the positions, velocities, and accelerations by taking into account the limitations of the joint velocities, accelerations, jerks, and torques. The flexible polyhedron search is utilized to calculate the optimum time interval between each pair of adjacent knots minimizing the total traveling time in which departure and arrival velocities, accelerations are equal to zero. The final trajectories pass by the given knots with a minimum traveling time and without overshooting nor wondering such that Robotic manipulator can be used more efficiently. Pascal programs are developed to implement the algorithm, and results are illustrated by means of the numerical of the Puma robot operation.
우광방,홍수원 연세대학교 대학원 1987 延世論叢 Vol.23 No.1
In order to maximize the capability of robot and to execute the given task during the least minimum time, this paper presents the algorithm which enables robot manipulator to move between two points in Cartesian space optimally when it satisfies the constraints of the specified trajectory function and input torque constraints. Specifying traveling path between any two points in the task space, trajectory function is described by the parameters representing joints of the manipulator and by the single parameter representing the trajectory. The trajectory function is incorporated into the dynamic equation of robot in which change in its manipulator position is expressed in terms of change in the values of the parameters that produce optimal solution. Input force torque constraints are coverted to the parameters of the dynamic equation and there is no need to restrict the range of the input torque. Phase plane is implemented that consists of the pseudo velocity and position of the joints. The pseudo velocity is derived from characterisitcs of the dynamic equation, and the admissible range of the manipulator velocity is designed on the phase plane. The above algorithm is applied to operations of the manipulator which has prismatic joint and rotational joint, and computer simulation is carried out Under several constraints, the optimal trajectory is generated and the trajectory can traverse between two points in Cartesian space with minimum time.
의공학학적 기법을 사용한 간암 치료경과의 정량 : ( Emission CT Imaging )
우광방,주기환 연세대학교 대학원 1983 延世論叢 Vol.20 No.1
The computed topography techniques presently play the most important role in the field of medical electronics, and are indispensible in detecting and quantitizing the abnormality in human body without destroying it. The present study was aimed to investigate the compensation of attenuation effects in emission computed tomography using single photon emission source. The most difficult and fundamental problem in the development of algorithms for emission computed tomography is to eliminate the attenuation effects. The various mcthods for solving this problem has been developed, including talc iterative method which requires the large capacity computer and the complexed computation procedure. Taking into account this point, the present study has used the simple algorithms for the image reconstruction called the convolution method or filter-back-projection method. In addition, the two-step image compensation method has been employed for compensating attenuation effects. This method was so effective that it enables one to quantitize the emission uptake and to allow the localization of lesion. When accuracy is not essential, the secondary compensation procedure can be omitted for saving the computation time. The visual and quantitative analyses of the liver phantom section image utilizing the two-step image compensation method revealed considerable improvement of the compensated images.