• Journal of Biomedical Engineering Research
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• v.5 no.1
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• pp.5-8
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• 1984

As the ensemble averaged dz/dt signal during exercise gets smoothed, it is difficult to find the distinctive marks for estimation of stroke volume. The cross correlation function was made use of estmating these marks for automatic calculation by computer from the ensemble averaged dz/dt signal. LVET(Left Ventricular Ejection Time) and stroke volume were estimated based on the calculated parameters from the characteristic points. LVET, stroke volume calculated by hand, by the ensemble average and the cross correlation were compared for accuracy validation.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.217-218
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• 1998

We propose a new digital beamforming algorithm using an interpolation filter in ultrasonic imaging systems. We compared the performances of the proposed algorithm to those of the conventional digital bemforming algorisms, post-beamformer and phase rotation beamformer, by a computer simulation and experiments. The results show that the proposed algorithm has better performance than the others.

• 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 Pediatrics of Korean Medicine
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• v.17 no.2
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• pp.1-13
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• 2003

Objectives: The purpose of this study was to suggest a scientific method for measurement of children's growth development. Ultrasonic image of calcaneus bone has some advantages that it is harmless to human body and apply a new imaging analysis algorithm. it can be used for the diagnosis of growth analyzed the opening degree of growth plate and bone density. Methods: This clinical study have been carried out with the 57 case(male 24, female 33) of the children aged 5 to 14 years old who visited in Department of Pediatrics, Dongguk university Bundang Oriental Hospital. Bone maturity is measured by the opening degree of growth plate and bone density in ultrasonic image of calcaneus bone This study were designed to investigate the relationship of the development of children and the calcaneus bone maturity. Result: The opening degree of growth plate was no change in aged 5-10 years for male and 5-9 years for female but decreased significantly from aged 11 years for male and 10 years for female. the bone density was no change in aged 5-12 years for male and 5-11 years for female but increased significantly from aged 13 years for male and 12 years for female. it was confirmed that bone maturity in female is more rapid than in male. The opening degree of growth plate of claclneus bone was correlated with age, height, weight. The bone density was correlated with age, height, weight, BMI in this suudy(P<0.001) Conclusion: The opening degree of growth plate and bone density of calcaneus bone are sufficient diagnostic worth as an index to predict adolescent growth.

• Journal of Biomedical Engineering Research
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• v.19 no.3
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• pp.321-325
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• 1998

This paper presents a simple, practical, and efficient method for estimating the speed of sound in reflection mode in ultrasound medical imaging. Its accurate determination is indispensable in order to obtain both good resolution and correct geometrical and volumetric information about human organs such as heart and kidney. Up to now, there have been several methods available, but they all suffer from either poor performance or high complexity. The proposed method finds out an optimum focusing delay profile in such a way that the brightness in a region of interest is maximized using continuous dynamic focusing in receive under fixed transmit focusing. Experiments carried out on a real ultrasound medical phantom reveals that the method a quite simple and effective in providing good speed of sound estimation, hence improved resolution and images, adding to dignostic utility.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.29 no.4
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• pp.292-300
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• 1993

Acoustical imaging has made brilliant progress in the medical science field, and has also made much progress in the nondestructive testing and under water acoustics applications since doctor Dussik brother has studied about possibilities of making images of brain by recording variations in the intensity of ultrasonic beam from head in 1937. In this paper an acoustical image is reconstructed with the power spectra analysed by impulse ultrasound wave generated by electrodynamic transducer(EDT). The EDT generates the impulse ultrasound of 77KHz in center frequency and 120KHz in bandwidth at -20dB by 1200V exciter in this experiment. The impulse ultrasound has the dominant frequency components of 47KHz, 177KHz, 110KHz and 155KHz. The U shape object is adopted in making an acoustical image. The resulted spectral acoustical images are different from the optical view of the U shape object. However the image reconstructed from 110KHz spectrum is very similar to the original optical shape of the object. Even KHz level impulse sound of 70$\mu$sec pulse width is found to be useful in reconstructing acoustical imaging improvement.

• Physical Therapy Korea
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• v.20 no.2
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• pp.38-45
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• 2013

This study was conducted in order to examine whether abdominal draw-in maneuver (ADIM) with isometric shoulder flexion, extension, adduction, and abduction selectively contracted deep abdominal muscles. This study's subjects were 13 males 17 females. In order to evaluate the comparison of effects of ADIM and ADIM with isometric shoulder flexion, extension, adduction and abduction, measurements were made on transverse abdominis (TrA), internal oblique (IO), and external oblique (EO) using a real-time ultrasonic diagnostic imaging system. Each position was repetitively measured three times with a real-time ultrasonic diagnostic imaging system and their mean values were used for analysis. The ADIM with isometric shoulder flexion, extension, adduction and abduction significantly increased the thickness of TrA relative to the ADIM only (p<.05). The ADIM with isometric shoulder abduction significantly increased the thickness of IO compared to the ADIM only (p<.05). The ADIM with isometric shoulder extension and abduction significantly decreased the thickness of EO compared to the ADIM only and the ADIM with isometric shoulder extension significantly decreased the thickness of EO relative to the ADIM with isometric shoulder adduction (p<.05). ADIM with isometric shoulder abduction is an effective method to selectively strengthen deep abdominal muscles and therefore may be employed as an intervention for trunk stabilization.

• Journal of Sensor Science and Technology
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• v.29 no.1
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• pp.33-39
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• 2020

Typically, photoacoustic images are obtained in water or gelatin because the impedance of these mediums is similar to that of the human body. However, these acoustic mediums can have an additional mass effect that changes the resonance frequency of the transducer. The acoustic radiation impedance in air is negligible because it is very small compared to that of the transducer. However, the high acoustic impedance of mediums such as the human body and water is quite large compared to that of air, making it difficult to ignore. Specifically, in a case where the equivalent mass is very small, such as with a micro-machined ultrasound transducer, the additional mass effects of the acoustic medium should be considered for an accurate resonance frequency design. In this study, a piezoelectric micro-machined ultrasonic transducer (pMUT) was designed to have a resonance frequency of 10 MHz in the acoustic medium of water, which has similar impedance as the human body. At that time, the resonance frequency of the pMUT in air was calculated at 15.2 MHz. When measuring the center displacement of the manufactured pMUT using a laser vibrometer, the resonance frequencies were measured as 14.3-15.1 MHz, which is consistent with the finite element method (FEM) simulation results. Finally, photoacoustic images of human hair samples were successfully obtained using the fabricated pMUT.

• Journal of Powder Materials
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• v.24 no.3
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• pp.216-222
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• 2017

Synthesized monocrystalline nanodiamond (nD) particles are heat-treated at various temperatures to produce highly structured diamond crystals. The heat-treated nDs show different weight loss ratios during thermogravimetric analysis. The crystallinities of the heat-treated nDs are analyzed using Raman spectroscopy. The average particle sizes of the heat-treated nDs are measured by a dynamic light scattering (DLS) system and direct imaging observation methods. Moreover, individual dispersion behaviors of the heat-treated nD particles are investigated based on ultrasonic dispersion methods. The average particle sizes of the dispersed nDs according to the two different measurement methods show very similar size distributions. Thus, it is possible to produce highly crystallized nD powder particles by a heat-treatment process, and the nD particles are relatively easy to disperse individually without any dispersant. The heat-treated nDs can lead to potential applications such as in nanocomposites, quantum dots, and biomedical materials.

• The Journal of the Acoustical Society of Korea
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• v.32 no.6
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• pp.502-508
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• 2013

In this paper, 2D array transducers using a conductive backer similar to 1-3 composites have been designed, fabricated, and evaluated. The conductive backer was based on well known manufacturing process of 1-3 composites with affordable ingredients. The 2D array transducer had 4,096 elements designed to have 3.5 MHz center frequency and a fractional bandwidth over 60 %. Fabricated prototype of the transducer satisfied the specifications in the center frequency and bandwidth. Performance over the entire elements was so uniform that the standard deviation was less than 0.81 dB. Thus applicability of the conductive backer proposed in this work to 2D array transducers was verified.