• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.34-36
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• 1989

Since the linear step motor(LSM) has the merits which can be controlled the position and velocity by using the micro-computer and has no mechanical transducer such as belt and gear, it's usefullness has been fitted for the printer, x-y plotter, OA machinery and so on. In designing the LSM, we are faced up to the calculation of forces. in this paper, the permeance modeling method suited for the design of transverse flux type linear step motor(TFM) is presented and simulated.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.1
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• pp.1-6
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• 2013

Ultrasonic guided wave techniques have been widely used for long range nondestructive detection in tube-like structures. The present paper investigates the ultrasonic linear and nonlinear parameters for evaluating the thermal damage in aluminum pipe. Specimens were subjected to thermal loading. Flexible polyvinylidene fluoride (PVDF) comb transducers were used to generate and receive the ultrasonic waves. The second harmonic wave generation technique was used to check the material nonlinearity change after different heat loadings. The conventional linear ultrasonic approach based on attenuation was also used to evaluate the thermal damages in specimens. The results show that the proposed experimental setup is viable to assess the thermal damage in an aluminum pipe. The ultrasonic nonlinear parameter is a promising candidate for the prediction of micro-damages in a tube-like structure.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.27 no.1
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• pp.31-40
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• 1991

This paper described on the availability fo the underwater telemetering by the ulterasonic multi-beam system made as a trial to expand detectable range of the fish school. The ultrasonic multi-beam system consisted of four transducers which reconstructed with the existing net recorder. The experiment for the telemetering carried out in the set net fishing ground. The results obtained are summerized as follows: 1. The detectable distance of a target by the linear arrangement of four transducers increased according to the sea depth and the interval between transducers. 2. When the fish school in the entrance of set net was measured by linear arrangement of transducers it was entered in depth of 2.5~3.5m at near position of leader, and in depth of 3.5~4.5m at near position of door net. 3. The deviations of error between the actual position and the position by transducer in case of the target depth 1m, 1.5m, 2m were 5.9~27.1cm, 3.2~28.9cm, 3.5~25.8cm respectively, and 68.3% probability radius of them were 14.6cm, 17.7cm, 17.0cm respectively. 4. When the fish school in the fish court of set net was measured by plane arrangement of transducer it was entered toward the opposite direction of tide current. 5. The available distance of telemetering by the multi-beam transducer was 1.8km and the telemetering was possible to control everywhere in case of sea depth more than three meters.

• Journal of the Korean Society of Radiology
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• v.9 no.7
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• pp.425-431
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• 2015

Measurement accuracy was evaluated for the respiratory air flow transducer developed for applications under emergent situations. Pressure-Flow calibration equation was obtained by acquisition of air flow signals from the transducer in response to 6 flow waveforms, similar to those of artificial ventilation, generated by the standard flow generator system. Tidal volume and maximal flow rate were calculated on the flow signal then compared with the error-free data obtained by the linear displacement transducer of the flow generator system. Mean relative error of the tidal volume was within 3% and that of the maximal flow rate, approximately 5%, demonstrating accurate enough measurements. Therefore, the transducer could be applied to emergent situations to monitor the respiratory air flow signal as well as diagnostic parameters in real time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.325-325
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• 2010

Piezoelectric linear motors have been widely studied for auto focusing devices of digital cameras and cellular phones due to their simple structure. In this paper, we confirmed that novel piezoelectric butterfly linear motor was fabricated and its dynamic properties were analyzed. The piezoelectric transducer (having size $9{\times}8{\times}1\;mm^3$) is composed of an elastic plate, which includes a tip for energy transfer and two fixing protrusions for fixture, and two piezoelectric ceramics. The butterfly linear motor has been designed and optimized using A TILA simulation program. The superposed motion is an elliptical vibration on the tip. The actual movement of the manufactured actuator was confirmed by a 3D laser dopier vibrometer and compared with the simulation results. The results of numerical study and experimental investigation will be used for the future optimization of the actuator and the realization of the advanced ultrasonic motor.

• Proceedings of the Acoustical Society of Korea Conference
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• 1991.06a
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• pp.136-141
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• 1991

초음파 영상 진단기에서 영상의 질을 높이기 위해서는 넓은 범우에서 높은 측 방향 해상도가 요구된다. 측 방향 해상도는 변환기에 의해 발생되는 초음파 빔폭에 의해 좌우되는데 기존의 변환기는 초점 부근에서는 빔폭이 매우 좁으나 집속 범위가 제한되는 단점이 있다. 본 논문에서는 넓은 범위에서 균일한 빔폭을 얻을 수 있는 새로운 형태의 변환기를 제안하고 변환기에 의한 음장 분포를 전산기 모의 실험을 통해 구하였으며 그 결과 초점 부근에서는 빔 폭이 기존의 변환기에 비해 다소 넓어지나 집속 범위가 기존의 변화기에 비해 넓어지는 것을 확인할 수 있었다.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.7 no.1
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• pp.28-32
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• 2014

Purpose: We aim to determine sciatic nerve bifurcation location and depth at the level of the popliteal fossa in Korean female. Materials and Methods: Thirty three subjects were enrolled in Korean female. M-turbo ultrasound system (SonoSite, bothell, WA, USA)with 38 mm high frequency linear array transducer, 13-6 MHz probe was used for ultrasound measurements. With subject lying prone, the location of the sciatic nerve in relation to the popliteal crease and skin to nerve distance were assessed via ultrasound. Analyses were performed with SAS version 9.3 using multiple linear regression. Results: Thirty three subjects were enrolled. Distance from the popliteal crease to the sciatic nerve was 4.5-7.5 (mean 5.7 cm), and the depth of the sciatic nerve from the skin was 1.8-3.2 (mean 2.4 cm). Multiple linear regression for the usefulness of the model has a p value of 0.036, shows between weight and depth. Conclusion: We show that variability exists for sciatic nerve bifurcation location in Korean female, The success rate is creased if consider the relations between weight and depth when performs sciatic nerve block in Korean female. In our study, a sciatic nerve block is recommend that performed 7.5 cm proximal to the crease in the popliteal fossa.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2749-2752
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• 2003

Magnetocardiography is a very weak biomagnetic field generated from the heart. Since the magnitude of the biomagnetic field is in the order of a few pico Tesla, it is measured with a superconducting quantum interference device (SQUID). SQUID is a transducer converting magnetic flux to voltage, however, its range of linear conversion is very restricted. In order to overcome the narrow dynamic range. a flux locked loop is used to feedback the output field with opposite polarity to the input field so that the total Held becomes zero. This prevents the operating point of the SQUID from moving too far away from the null point thereby escape from the linear region. In this paper, an emulator for the SQUID sensor and feedback coil is proposed. Magnetic courting between the original field and the generated field by the feedback coil is emulated by electronic circuits. By using the emulator, FLL circuits are analyzed and optimized without SQUID sensors. The emulator may be used as a test signal for multi-channel gain calibration and system maintenance.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.3
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• pp.214-219
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• 2000

This paper presents a recoil and counter recoil motion measurement system using linear variable differential transformers (LVDT). The output of the LVDT is obtained from the differential voltage of the secondary transformers. Since a transducer core is attached to the motion body, the output is directly proportional to the movement length of the core. Displacement, velocity and acceleration are measured from the LVDT. With a comparison between the measurement result and the reference value obtained by the highly accurate Vernier calipers, it is proved that the measurement system with the LVDT is applicable to the test of the moving part of the mechanism with better accuracy.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.7
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• pp.72-78
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• 2008

The line-of-sight(LOS) stabilization system is a precision electro-mechanical gimbals assembly for suppressing vibration due to its environment and tracking the target in a desired direction. This paper describes the design of gimbals system to reject the disturbance and to improve stabilization. The controller consists of a DSP with transducer and actuator interfaces. Unknown parameters of the gimbals are estimated by the signal compression method. The cross-correlation coefficient between the impulse response from the assumed model and the one from model of the gimbals is used to obtain the better estimation. The quasi-impulse response through linear element included in the gimbals could be obtained by the signal compression method. The unknown parameter of the linear element could be estimated as comparing the bode plots for impulse response from gimbals with them from model's response.