• Smart Structures and Systems
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• 제22권2호
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• pp.223-230
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• 2018

This study examines a non-contact laser scanning-based ultrasound system, called an angular scan pulse-echo ultrasonic propagation imager (A-PE-UPI), that uses coincided laser beams for ultrasonic sensing and generation. A laser Doppler vibrometer is used for sensing, while a diode pumped solid state (DPSS) Q-switched laser is used for generation of thermoelastic waves. A high-speed raster scanning of up to 10-kHz is achieved using a galvano-motorized mirror scanner that allows for coincided sensing and for the generation beam to perform two-dimensional scanning without causing any harm to the surface under inspection. This process allows for the visualization of longitudinal wave propagation through-the-thickness. A pulse-echo ultrasonic wave propagation imaging algorithm (PE-UWPI) is used for on-the-fly damage visualization of the structure. The presented system is very effective for high-speed, localized, non-contact, and non-destructive inspection of aerospace structures. The system is tested on an aluminum honeycomb sandwich with disbonds and a carbon fiber-reinforced plastic (CFRP) honeycomb sandwich with a layer overlap. Inspection is performed at a 10-kHz scanning speed that takes 16 seconds to scan a $100{\times}100mm^2$ area with a scan interval of 0.25 mm. Finally, a comparison is presented between angular-scanning and a linear-scanning-based pulse-echo UPI system. The results show that the proposed system can successfully visualize defects in the inspected specimens.

• Radiation Oncology Journal
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• 제31권1호
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• pp.41-47
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• 2013

Purpose: To describe the early experience of analyzing variations and time trends in bladder volume of the rectal cancer patients who received bladder ultrasound scan. Materials and Methods: We identified 20 consecutive rectal cancer patients who received whole pelvic radiotherapy (RT) and bladder ultrasound scan between February and April 2012. Before simulation and during the entire course of treatment, patients were scanned with portable automated ultrasonic bladder scanner, 5 times consecutively, and the median value was reported. Then a radiation oncologist contoured the bladder inner wall shown on simulation computed tomography (CT) and calculated its volume. Results: Before simulation, the median bladder volume measured using simulation CT and bladder ultrasound scan was 427 mL (range, 74 to 1,172 mL) and 417 mL (range, 147 to 1,245 mL), respectively. There was strong linear correlation (R = 0.93, p < 0.001) between the two results. During the course of treatment, there were wide variations in the bladder volume and every time, measurements were below the baseline with statistical significance (12/16). At 6 weeks after RT, the median volume was reduced by 59.3% to 175 mL. Compared to the baseline, bladder volume was reduced by 38% or 161 mL on average every week for 6 weeks. Conclusion: To our knowledge, this study is the first to prove that there are bladder volume variations and a reduction in bladder volume in rectal cancer patients. Moreover, our results will serve as the basis for implementation of bladder training to patients receiving RT with full bladder.

• 대한의용생체공학회:의공학회지
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• 제21권4호
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• pp.419-431
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• 2000

본 논문에서는 디지털 스캔 컨버터(DSC, digital scan converter)에 의한 왜곡이 근본적으로 발생하지 않는 새로운 초음파 영상 방법으로서 표시장치의 화소에 직접 수신 집속하는 기법(DPBF, display-pixel-based focusing)과 이를 구현하기 위한 초음파 영상 장치의 구조를 제안한다. 제안한 기법은 극 좌표에 위치하는 샘플링 점들 대신에 직각좌표상의 화소들에 직접 수신 집속 함으로써 DSC의 역할을 제거하였다. DPBF 기법을 적용한 영상에는 DSC에 의한 허상 및 구획화 현상 등이 나타나지 않으며, 일반적인 방법에 의한 영상에 비해 보다 세밀한 영상을 제공한다는 사실을 검증할 수 있었다. 본 논문은 DSC에 의한 보간 효과가 두 개의 비교 영상 A, B 간에 미치는 정도를 정량적으로 평가하기 위해서 영상거침 비(ICRA/B, Image Coarseness Ratio)를 새로운 성능 측정 방법으로 정의하였다. 이 ICRA/B를 이용하여 비교 영상간 거친 정도를 정량적으로 측정하였다.

• 한국방사선학회논문지
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• 제16권3호
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• pp.289-294
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• 2022

본 연구는 CT와 USG 스캔 데이터를 이용하여 팬텀 실험과 환자 스캔 데이터를 활용하는 임상실험으로 체적 측정의 정확도 및 유용성을 알아보았다. 그 결과 CT와 USG 스캔 데이터 모두 다양한 체적의 실제 원형 팬텀의 체적과 유의한 차이가 없었으며(p>0.05), 동일 환자의 방광 체적 측정 결과 CT 데이터는 236.9±2.1, USG 영상은 236.9±1로 측정되어 통계분석 결과 유의한 차이가 없는 것으로 분석되었다(p>0.05). 본 결과의 임상 적용은 추가 임상실험이 필요하지만, 환자 피폭, 검사자의 스캔 기술, 그리고 CT 재구성 경험 등을 고려하여 CT 또는 초음파 장치를 선택 적용한다면 의료영상을 활용한 체적 측정의 유용성 측면에서 기초자료로 적용 가치가 있을 것으로 사료된다.

• 대한의용생체공학회:의공학회지
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• 제20권4호
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• pp.503-513
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• 1999

본 논문에서는 일반적인 합성구경기법에 대한 통합 모형을 제시하고 수학적인 해석을 통하여 합성구경 기법들에 대한 초음파 빔패턴의 단일 표현식을 유도하였다. 이 결과를 이용하여 기존의 합성구경 기법들에 대한 성능을 분석하고 비교하였으며, 선형주사 영상에 적합한 새로운 합성구경 기법을 제안하였다. 제안된 방법은 모든 영상점에서 양방향 동적 집속이 가능하며, 이를 실제 영상에 적용하여 의료용 초음파 B-모드 영상의 해상도를 획기적으로 개선할 수 있다. 제안된 방법에 의하여 집속된 초음파 빔패턴은 기존의 방식과 비교하여 주엽의 폭이 절반으로 감소하고 측엽의 크기는 유사하다. 컴퓨터 모사실험을 통하여 본 논문의 해석결과와 제안된 합성구경 기법의 타당성을 검증하였다.

• 대한정형외과 초음파학회지
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• 제4권1호
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• pp.42-49
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• 2011

초음파 검사는 다양한 견관절 질환을 검사하는 강력하고 유용한 방법이다. 최근 들어 고해상도 변환기의 사용과 술기의 발전으로 회전근 개 질환을 비롯한 견관절 주위의 질환을 진단하는 정확성이 향상되고 있다. 하지만, 시술자의 숙련도에 따라 다양한 결과를 나타내는 단점이 있어 주의를 요한다. 본 강좌에서는 견관절 주위의 효과적인 초음파 검사 방법을 제시하고자 한다.

• 대한의용생체공학회:의공학회지
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• 제17권4호
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• pp.469-478
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• 1996

In the conventional digital ultrasound scanner, the reflected signal is sampled either in polar coordinates of R-$\theta$ method, or in Cartesian coordinates of uniform ladder algorithm (ULA). The R-$\theta$ scan method necessitates a coordinate transform process which makes hardware complex in comparison with ULA scan mrthoA In spite of this complexity, R-$\theta$ method has a good resolution in ultrasonographic (US) image, since scan direction of the US imaging is a radial direction. In this paper, a new digital scan converter is proposed, which is named the radius uniform ladder algorithm (RULA). The RULA has the rome scan direction as the US scanning in the radial direction and as the display space in the $\theta$ direction. In tllis new approach, sampled points we uniformly distributed in each horizontal line i.n well as in each radial ray so that the data are displayed in the Cartesian coordinates by the 1-D interpolation process. The propped algorithm has an uniform resolution in the periphery and the center field in comparison with equi-angle ULA and equi-interval ULA. To extend the scan angle, concentric square raster sampling (CSRS) is adopted with reduction of discontinuities on the junctions between horizontal scan and vertical scan. The discontinuities are reduced by using the hmction filtering along the $\theta$ direction.

• 공학기술논문지
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• 제11권4호
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• pp.245-251
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• 2018

Terahertz waves (T-ray) was extensively studied for the NDE (nondestructive evaluation) of characterization of trailing edges for a use of turbines composed with composite materials. The used NDE system were consisted of both CW(Continuous wave) and TDS (Time domain spectroscopy). The FRP composites were utilized for two kinds of both trailing edges of wind energy (non-conducting polymeric composites) and carbon fiber composites with conducting properties. The signals of T-ray in the TDS (Time domain spectroscopy) mode resembles almost that of ultrasound waves; however, a terahertz pulse could not penetrate a material with conductivity unlike ultrasound. Also, a method was suggested to obtain the "n" in the materials, which is called the refractive index (n). The data of refractive index (n) could be solved for the trailing edges. The trailing edges were scanned for characterization and inspection. C-scan and B-scan images were obtained and best optimal NDE techniques were suggested for complicated geometry samples by terahertz radiation. Especially, it is found that the defect image of T-ray corresponded with defect locations for the trailing edges of wind mill.

• 비파괴검사학회지
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• 제29권3호
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• pp.235-241
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• 2009

Composite wood materials are very sensitive to water and inspection without any coupling medium of a liquid is really needed to wood materials due to the permeation of coupling medium such as water. However, air-coupled ultrasound has obvious advantages over water-coupled experimentation compared with conventional C-scanner. In this work, it is desirable to perform contact-less nondestructive evaluation to assess wood material homogeneity. A wood material was nondestructively characterized with non-contact and contact modes to measure ultrasonic velocity using automated data acquisition software. We have utilized a proposed peak-delay measurement method. Also through transmission mode was performed because of the main limitation for air-coupled transducers, which is the acoustic impedance mismatch between most materials and air. The variation of ultrasonic velocity was found to be somewhat difference due to air-coupled limitations over conventional scan images. However, conventional C-scan images are well agreed with increasing the resin-infiltrated time as expected. Finally, we have developed a measurement system of an ultrasonic velocity based on data acquisition software for obtaining ultrasonic quantitative data for correlation with C-scan images.

• 한국임상수의학회지
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• 제28권4호
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• pp.408-414
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• 2011

This study was carried out to analyze the utilization of ultrasound machines in animal hospitals and focused on surveying the present condition of diagnostic ultrasound on veterinary medicine in South Korea. Total 279 veterinary hospitals were surveyed with e-mail questionnaires or telephone survey. E-mail questionnaires consist of 17 items of questions including existence of ultrasound machine, types of ultrasound machine, ultrasound examination costs, frequency, purposes, other diagnostic imaging equipments, and referring system of ultrasound. Telephone surveys asked about the existence of the ultrasound machine and types of the ultrasound machine to 279 animal hospitals. Two hundred and seventy-one out of 279 animal hospitals holds ultrasound machine. Seventy-two percents clinics purchased used ultrasonographic machines and mean years after the date of manufacture is 7.5 years and the proportion of superannuated machines are relatively high. Also many clinicians prefer single organ scanning rather than general scan technique and more than 60% of clinics perform ultrasonographic examination less than 5 times a week. Clinics located in Seoul area tend to have more expensive and brand-new ultrasonographic machines and the distribution of radiology specialist are higher in this area. Problems associated with the present condition were oversupply of machines, unequal distribution of the medical equipment in different localities, ineffective use of the medical equipment, and high percentage of old poor-quality medical equipments. There should be a viable alternative proposal to control amount and quality of the ultrasound machines. Also, the improved management system for the ultrasound machine is required.