• Journal of Biomedical Engineering Research
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• v.45 no.3
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• pp.118-127
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• 2024

Commonly deep learning methods for enhancing the quality of medical images use unpaired dataset due to the impracticality of acquiring paired dataset through commercial imaging system. In this paper, we propose a supervised learning method to enhance the quality of ultrasound images. The U-net model is designed by incorporating a divide-and-conquer approach that divides and processes an image into four parts to overcome data shortage and shorten the learning time. The proposed model is trained using paired dataset consisting of 828 pairs of low-quality and high-quality images with a resolution of 512x512 pixels obtained by varying the number of channels for the same subject. Out of a total of 828 pairs of images, 684 pairs are used as the training dataset, while the remaining 144 pairs served as the test dataset. In the test results, the average Mean Squared Error (MSE) was reduced from 87.6884 in the low-quality images to 45.5108 in the restored images. Additionally, the average Peak Signal-to-Noise Ratio (PSNR) was improved from 28.7550 to 31.8063, and the average Structural Similarity Index (SSIM) was increased from 0.4755 to 0.8511, demonstrating significant enhancements in image quality.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.05
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• pp.81-85
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• 1993

Despite the simplicity of processing, conventional autocorrelation function (ACF) method for the precise determination of fetal heart rate (FHR) has many problems. In the case of weak or noise corrupted Doppler ultrasound singnals, the ACF method is very sensitive to the threshold level and data window length. It is real troublesome to extract FHR when there is a data loss. To overcome these problems, the high resolution pitch detection algorithm is adapted to estimate the FHR. The FHR is determined from the correlation of two interconnected segments by its maximum correlation value. FHR is compensated with a constant correlation threshold in a greatly smeared noise signal. This method yields more accurate, robust and reliable than the ACF method.

• Journal of Biomedical Engineering Research
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• v.16 no.2
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• pp.175-182
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• 1995

Despite the simplicity of processing, a conventional autocorrelation function (ACF) method for the precise determination of fetal heart rate (FHR) has many problems. In case of weak or noise corrupted Doppler ultrasound signal, the ACF method is very sensitive to the threshold level and data window length. It is very troublesome to extract FHR when there is a data loss. To overcome these problems, the high resolution pitch detection algorithm was adopted to estimate the FHR. This method is more accurate, robust and reliable than the ACF method. With a lot of calculation, however, it is impossible to process real time FHR estimation. This paper is presented a new FHR estimation algorithm for real time processing and studied the real time FHR monitoring system by high resolution pitch detection algorithm.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.4 no.1
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• pp.42-49
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• 2011

Ultrasonography is a powerful and useful method for the examination of the various shoulder diseases. The use of high-resolution transducer and technical evolution allowed the improvement of the accuracy of detection of various shoulder pathology including the rotator cuff disease. However, its limitation is that there is marked disparity in the interpretation according to the operators' experience. This article describes the appropriate scan technique of ultrasonography around shoulder.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.1 no.2
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• pp.122-127
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• 2008

Ultrasonography is a powerful and useful method for the examination of the various shoulder diseases. The use of high-resolution transducer and technical evolution allowed the improvement of the accuracy of detection of the rotator cuff disease. However, its limitation is that there is marked disparity in the interpretation according to the operators' experience. This article describes the ultrasonographic findings of rotator cuff pathology compared to the MR (magnetic resonance) imaging and arthroscopic findings for helping the interpretation of ultrasonographic picture.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.5
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• pp.2361-2367
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• 2016

Since 1980, endoscopic ultrasound (EUS) has been used as an important tool for the evaluation of malignant diseases in hollow viscus and bilio-pancreas, as well as sub-epithelial tumors. The high-resolution capacity and low penetration depth of EUS make it possible to obtain highly detailed images of the gastrointestinal wall and immediate surroundings to a depth of 4-5 cm. Thus, over the past 35 years, EUS succeeded to modify management in significant number of cases and is now considered a gold standard tool for many gastrointestinal diseases, especially in the pancreatico-biliary tract, and adjuvant needle insertion now allows access to remote lesions that were difficult to reach in the past. With the growing spectrum of indications, tissue sampling for diagnostic purposes has become common. In this review, we aim to highlight the expanding spectrum of EUS indications and uses in staging of upper gastrointestinal malignancies, especially esophageal, gastric and ampullary tumors.

• International Journal of Vascular Biomedical Engineering
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• v.3 no.1
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• pp.6-13
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• 2005

Individual clinical significance of each layer of CCA (common carotid artery) has not been well studied. We intended to measure the intima thickness (IT), media thickness (MT), and intima-media thickness (IMT) of CCA separately and tried to analyze the clinical significance. One hundred fifty one consecutive patients (mean age: $57{\pm}15$ years; 77 males, 74 females) underwent CCA scanning using high-resolution ultrasound. The images were off-line analyzed using B-mode ultrasound image processing, devised for individual measurement of IT and MT as well as IMT. The mean coefficients of variation of new method measuring IT, MT, and IMT separately were 0.16% for IMT and 0.21% for both IT and MT. The IT (p < 0.01), MT (p < 0.01) as well as IMT (p < 0.001) of patients with atherosclerotic disease were significantly thicker than that of the patients without atherosclerotic disease. Patients with hypertension showed significantly thicker IT (p < 0.01), MT (p < 0.001), and IMT (p < 0.001) than that of the patients without hypertension. However, only IT was thicker in patients with smoking (p<0.01) than that of the patients without smoking.

• Journal of the Korean Society of Radiology
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• v.15 no.4
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• pp.463-472
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• 2021

Demand for examinations using transvaginal transducer with high frequencies is increasing to observe pelvic organs in gynecological ultrasound tests. However, the quality control of the replacement probe in clinical trials is not properly implemented and the evaluation criteria have not been established. Therefore, 58 transvaginal transducers and 20 convex transducers were applied to the ATS-539 ultrasound phantom for 20 ultrasound devices currently in clinical use to obtain their respective images and measure them quantitatively and qualitatively. For quantitative measurements, vertical measurement, horizontal measurement, and focal zone and qualitative measurements, dead zone, axial·lateral resolution, sensitivity, functional resolution, gray scale·dynamic range were performed. Quantitative statistical analysis showed significant differences between the two transducers in the lateral measurement and local area (p<0.05). qualitative comparative analysis showed differences in sensitivity and functional resolution. This occurs due to the difference in frequency between transducers and the transducer's injection geometry. Based on the above experiments, the tolerance for horizontal measurement is raised to 10% (±8 mm), the tolerance for sensitivity is observed up to 6 cm deep, which is 12 cm deep,which is the level of the third quartile (75%). The permissible range of functional resolution is up to 6 (12 cm), 6 (12 cm), 11 (11 cm), 9 (9 cm), 6 (6 cm) target, which is the level of the third quartile (75%). It is considered reasonable to adjust the depth of targets in gray scale·dynamic range to measure at a depth of 2 cm, which is 50% of the depth of 4 cm. As above, the criteria for evaluating the quality of transvaginal transducer for use in the past have been proposed and it is expected that this study will be used as a basic data for the production of phantom exclusively for transvaginal transducer in the future.

• Clinical and Experimental Pediatrics
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• v.52 no.10
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• pp.1136-1139
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• 2009

Purpose:It is critical that the exact gestational age of a newborn baby, especially premature baby, be determined to evaluate the status of a disease and its management and to estimate the prognosis of a patient. This study aimed to investigate an easy and accurate method to estimate gestational age on cranial ultrasound, requiring minimal additional time and equipment. Methods:A high-resolution coronal sonographic image was obtained via the anterior fontanel with a 5-12 Mhz linear probe after the usual cranial sonographic examination. We measured the depth of cerebral hemisphere, thickness of corpus callosum, and depth of cingulate sulcus and obtained the correlations between these factors and gestational age. Results:Depth of cingulate sulcus had the highest correlation coefficiency with gestational age (r=0.878, P=0.000). All the cases, except for 2 cases, had a gestational age of more than 37 weeks, when the depths of cingulate sulcus were more than 0.55 cm, and had a gestational age less than 34 weeks, when the depths of cingulate sulcus were less than 0.35 cm. Conclusion:Measurement of the depth of cingulate sulcus was a simple and accurate method to estimate the gestational age on cranial ultrasound. The gestational age is more than 37 weeks, when the depth of cingulate sulcus is more than 0.55 cm, and is less than 34 weeks, when the depth of cingulate sulcus is less than 0.35 cm.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.2
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• pp.112-119
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• 2015

Photoacoustic microscopy is capable of providing high-resolution molecular images, and its spatial resolution is typically determined by ultrasonic transducers used to receive the photoacoustic signals. Therefore, ultrasonic transducers for photoacoustic microscopy (PAM) should have a high operating frequency, broad bandwidth, and high signal-reception efficiency. Polyvinylidene fluoride (PVDF) is a suitable material. To take full advantage of this material, the selection of the backing material is crucial, as it influences the center frequency and bandwidth of the transducer. Therefore, we experimentally determined the most suitable backing material among EPO-TEK 301, E-Solder 3022, and RTV. For this, three PVDF high-frequency single-element transducers were fabricated with each backing material. The center frequency and -6 dB bandwidth of each transducer were ascertained by a pulse-echo test. The spatial resolution of each transducer was examined using wire-target images. The experimental results indicated that EPO-TEK 301 is the most suitable backing material for a PAM transducer. This material provides the highest signal magnitude and a reasonable bandwidth because a large portion of the energy propagates toward the front medium, and the PVDF resonates in the half-wave mode.