• Clinical Endoscopy
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• v.57 no.2
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• pp.164-174
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• 2024

Pancreatic cancers have a poor prognosis, and their incident rates have risen. Endoscopic ultrasonography (EUS) is an efficient and reliable diagnostic modality for pancreatic lesions, providing high spatial resolution. However, while EUS helps to detect minor pancreatic lesions, nearly all solid pancreatic lesions are hypoechoic, which creates difficulty in making differential diagnoses of pancreatic lesions. When diagnosing pancreatic lesions, the performance of image-enhanced EUS techniques is essential, such as EUS elastography or contrast-enhanced harmonic EUS (CH-EUS). CH-EUS diagnosis is based on assessing the vascularity of lesions, whereas tissue elasticity is measured via EUS elastography. Elastography is either strain or shear-wave, depending on the different mechanical properties being evaluated. The usefulness of enhanced EUS techniques is demonstrated in this review for the differential diagnosis of pancreatic lesions, including solid and cystic lesions, and pancreatic cancer staging.

• The Journal of the Acoustical Society of Korea
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• v.24 no.2
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• pp.78-86
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• 2005

This study considers the magnitude of the harmonic components radiated from the ultrasonic contrast agents (UCA) activated by a typical diagnostic ultrasound. The nonlinear dynamic response of UCA to a 2 MHz diagnostic ultrasound pulse was predicted using Gilmore Model. The elastic property of the shell membrane of the UCA was ignored in the numerical model. Simulation was carried out for the UCA varying from 1 - 9 $\mu$m in its initial radius and the driving diagnostic ultrasound whose mechanical index (MI) ranges from 0.125 to 8. The powers of the sub. ultra and second harmonics of the acoustic signal from the UCA activated were compared with that of the fundamental component. The results show that. if the UCA is bigger than its resonant size (2 $\mu$m in radius for the present case) the sub harmonic power was much bigger than the fundamental. In particular, the 2nd harmonic component currently used as an imaging parameter for the harmonic imaging, was predicted to be lower in power than both the sub and the ultra harmonic component. This study indicates that, for obtaining harmonic imaging with UCA, the sub or ultra harmonics could be taken as imaging parameters better than the 2nd harmonic component.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1083-1089
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• 2007

In this paper, we applied the CMRC to a resonator to improve the harmonic characteristic of VCO. The CMRC filters have some advantage. It is a small size as well as easy to manufacture than PBG, DGS and other filters. This paper was proposed by using CMRC for a VCO. The second harmonic of -42.83 dBc and the phase noise at 100 kHz offset of -95.83 dBc/Hz was achieved, respectively. The VCO has better second harmonic character by 15.73 dB and phase noise by 31.13 dB in case of CMRC applied behind a resonator than CMRC used as a resonator.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.5
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• pp.624-631
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• 2012

This paper presents a high-efficiency current mode class-D(CMCD) power amplifier for the 13.56 MHz band using a Guanella's 1:1 transmission-line transformer and filtering circuits at the output network. The second and third s are filtered out in the load network of the class-D amplifier. The implemented CMCD power amplifier exhibited a power gain of 13.4 dB and a high power-added efficiency(PAE) of 84.6 % at an output power of 44.4 dBm using the 13.56 MHz CW input signal. The second and third distortion levels were -50.3 dBc and -46.4 dBc at the same output power level, respectively.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1231_1231
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• 2009

• Proceedings of the Optical Society of Korea Conference
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• 1998.08a
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• pp.72-73
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• 1998

• Proceedings of the Optical Society of Korea Conference
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• 1998.08a
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• pp.74-75
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• 1998

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.64-65
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• 1999

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.158-159
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• 2004

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.301-302
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• 2008