• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.718-722
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• 2014

A method for estimating the cylindrical shape of a sound radiator is presented. It assumes that sound field can be measured by a linear array. A sound field, due to the radiator vibrating with uniform velocity, can be determined by its shape, size, and orientations. Measured data also can be varying from the array's position. To predict the shape of radiators from these measured data, mathematical relation between geometric parameter and measured information is needed. Assume that a radiator is cylinder, the magnitude and phase of measured pressure is related with the length and diameter of radiator, respectively. In this paper, the method for estimating length and shape of a finite cylinder by using its radiated pressure is proposed and verified through experiment.

• Smart Structures and Systems
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• v.32 no.1
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• pp.1-7
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• 2023

In modal analysis, the mode shape reflects the vibration characteristics of the structure, and thus it is widely performed for finite element model updating and structural health monitoring. Generally, the acceleration-based mode shape is suitable to express the characteristics of structures for the translational vibration; however, it is difficult to represent the rotational mode at boundary conditions. A tilt sensor and gyroscope capable of measuring rotational mode are used to analyze the overall behavior of the structure, but extracting its mode shape is the major challenge under the small vibration always. Herein, we conducted a feasibility study on a multi-mode shape estimating approach utilizing a single physical quantity signal. The basic concept of the proposed method is to receive multi-metric dynamic responses from two sensors and obtain mode shapes through bridge loading test with relatively large deformation. In addition, the linear transformation matrix for estimating two mode shapes is derived, and the mode shape based on the gyro sensor data is obtained by acceleration response using ambient vibration. Because the structure's behavior with respect to translational and rotational mode can be confirmed, the proposed method can obtain the total response of the structure considering boundary conditions. To verify the feasibility of the proposed method, we pre-measured dynamic data acquired from five accelerometers and five gyro sensors in a lab-scale test considering bridge structures, and obtained a linear transformation matrix for estimating the multi-mode shapes. In addition, the mode shapes for two physical quantities could be extracted by using only the acceleration data. Finally, the mode shapes estimated by the proposed method were compared with the mode shapes obtained from the two sensors. This study confirmed the applicability of the multi-mode shape estimation approach for accurate damage assessment using multi-dimensional mode shapes of bridge structures, and can be used to evaluate the behavior of structures under ambient vibration.

• The Journal of the Acoustical Society of Korea
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• v.39 no.4
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• pp.255-262
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• 2020

In modern passive sonar systems, a towed array sensor is used to minimize the effects of own ship noise and to get a higher SNR. The thin and long towed array sensor can be guided in a non-linear form according to the maneuvering of tow-ship. If this change of the array shape is not considered, the performance of beamformer may deteriorate. In order to properly beamform the elements in the array, an accurate estimate of the array shape is required. Various techniques exist for estimating the shape of the linear array. In the case of a method using a heading sensor, the estimation performance may be degraded due to the effect of heading sensor noise. As means of removing this potential error, weighted polynomial fitting technique for estimating array shape is developed here. In order to evaluate the performance of proposed method, we conducted computer simulation. From the experiments, it was confirmed that the proposed method is more robust to noise than the conventional method.

• Computers and Concrete
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• v.13 no.6
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• pp.781-798
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• 2014

Estimating the workability of self-compacting concrete (SCC) is very important both in laboratories and on construction site. A method using visual information during the mixing process was proposed in this paper to estimate the workability of SCC. First, fourteen specimens of concrete were produced by a single-shaft mixer. A digital camera was used to record all the mixing processes. Second, employing the digital image processing, the visual information from mixing process images was extracted. The concrete pushed by the rotating blades forms two boundaries in the images. The shape of the upper boundary and the vertical distance between the upper and lower boundaries were used as two visual features. Thirdly, slump flow test and V-funnel test were carried out to estimate the workability of each SCC. Finally, the vertical distance between the upper and lower boundaries andthe shape of the upper boundary were used as indicators to estimate the workability of SCC. The vertical distance between the upper and lower boundaries was related to the slump flow, the shape of the upper boundary was related to the V-funnel flow time. Based on these relationships, the workability of SCC could be estimated using the mixing process images. This estimating method was verified by three more experiments. The experimental results indicate that the proposed method could be used to automatically estimate SCC workability.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.10a
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• pp.71-78
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• 2006

The image of an object obtained by the radar is not corresponding to its true shape, because the image of an object observed by the radar is receiving an influence such as multiple-reflections and expanded in bearing because of the beam width of a radar. In addition, a radio wave does not hit the entire surface of an object. Therefore, the image of the front side of a ship facing a radar antenna corresponds to its true shape. In this paper, a method to estimate a ship's shape by means of the integration of the front parts of images obtained from radars is proposed. In addition, a matter, which is observation error of each radar, in using multi-radars, and the process included in the proposed method for solving the matter, are described. As a result of the experiment, the accuracy of about 3 degrees in ship's heading and about 14 meters in length and about 9 meters in beam was obtained.

• Journal of Biomedical Engineering Research
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• v.21 no.4
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• pp.411-417
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• 2000

This paper describes the analysis of the oscillometric method based on the shape of arterial pressure and proposal of a new algorithm for estimating the blood pressure by computer simulation. In the first step, the arterial pressure model which is able to control the shape of arterial pressure was designed and then we simulated the oscillometric model using both the existing exponential model showing the static arterial pressure-volume relation and the designed arterial pressure model. By analyzing the correlation of characteristic ratio based on the shape of arterial pressure, we could find that the characteristic ratio was not the only standard parameter for estimating systolic and diastolic pressure. We were able to estimate the shape of arterial pressure by computing the correlation of arterial pressure shape with oscillation shape. Finally, we proposed an algorithm which is able to estimate systolic and diastolic pressure according to pressure(Pp) table constructed from the relation of maximum amplitude of oscillation and arterial pressure shape. We tested 60 arterial pressure waveforms having various arterial pressure shape and pulse. As a results, the absolute deviation average values of the estimation of systolic, diastolic and mean pressure were 1.62%, 2.40% and 2.20%, respectively. In conclusions, the proposed algorithm showed the possibility of usefullness in estimating the blood pressure.

• Journal of Korean Medicine for Obesity Research
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• v.3 no.1
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• pp.85-93
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• 2003

Objective : The purpose of this study is to investigate the emotional roubles of the obese and their's relationship with obesity so as to be useful for treating the obesity and estimating it's prognosis. Method : This study investigates the fifteen statistical treatises for the emotional troubles of the obese, and distributes their's results into depression, perception of obesity, satisfaction of body shape, eating behavior, and other emotional troubles. Conclusions: 1. In the obese dissatisfaction and inferiority complex for body shape are one of the causes bring about depression. 2. Masked depression is often, so exact examination is needed and the treatment of depression is useful for treating the obesity and estimating it's prognosis. 3. In the obese correcting wrong body shape image and making them gain confidence in treatment of obesity is needed because they have low self-efficacy in overeating, high perception of obesity, and dissatisfaction of body shape. 4. The obese has a abnormal eating behavior and it is related with the emotion troubles such as depression, low self-esteem, and so forth.

• Communications for Statistical Applications and Methods
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• v.15 no.4
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• pp.543-549
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• 2008

Inspired by using a robust loss function in the support vector machine regression to control training error and the idea of robust template matching with M-estimator, Chen (2004) applies M-estimator techniques to gaussian radial basis functions and form a new class of robust kernels for the support vector machines. We are specially interested in the shape of the Huber's M-estimator in this context and propose a way to find the shape parameter of the Huber's M-estimating function. For simplicity, only the two-class classification problem is considered.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.274-277
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• 1999

This paper is concerned with estimating the mass of a loose part in the steam generator of a nuclear power plant. Although there is the basic principle known as “Hertz Theory”for estimating mass and energy of a spherical part impacted on an infinite flat plate, the theory is not directly applicable because real plants do not comply with the underlying ideal assumptions. (Say, the steam generator is of a cylindrical and hemisphere shape.) In this work, a practical method is developed based on the basic theory and considering amplitude and energy attenuation effects. Actually, the impact waves propagating along the plate to the sensor locations become significantly different in shape and frequency spectrum from the original waveform due to the plate and surrounding conditions, distance attenuation and damping loss. To show the validity of the present mass estimation algorithm, it has been applied to the mock-up impact test data and also to real plant data. The results show better performance comparing to the conventional Hertz schemes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.263-265
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• 2007

An ultrasonic linear motor using lambda shape vibrators has been designed and fabricated. The multiway ultrasonic motors mainly consist of an lambda shape ultrasonic vibrator which generates elliptical motions in beat. The lambda shape ultrasonic linear motor use longitudinal and bending vibration mode. In order to high precision motion control and multiway moving, piezoceramics were adhered to lambda shape brass elastic material. The finite element method was used to optimize dimension of ultrasonic vibrator and direction of vibratory displacement. As a result of estimating the characteristics of the ultrasonic linear motor, The results have shown that the lambda shape ultrasonic linear motor can be moved multiwav by using the phase control. Close agreement between the FEM results and experimental results obtained for the lambda shape ultrasonic linear motor.