• ETRI Journal
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• 제37권4호
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• pp.780-786
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• 2015

This paper describes an audio source separation that is based on nonnegative matrix factorization (NMF) and expectation maximization (EM). For stable and highperformance separation, an effective auxiliary source separation that extracts source residuals and reprojects them onto proper sources is proposed by taking into account an ambiguous region among sources and a source's refinement. Specifically, an additional NMF (model) is designed for the ambiguous region - whose elements are not easily represented by any existing or predefined NMFs of the sources. The residual signal can be extracted by inserting the aforementioned model into the NMF-EM-based audio separation. Then, it is refined by the weighted parameters of the separation and reprojected onto the separated sources. Experimental results demonstrate that the proposed scheme (outlined above) is more stable and outperforms existing algorithms by, on average, 4.4 dB in terms of the source distortion ratio.

• Applied Microscopy
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• 제48권4호
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• pp.130-131
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• 2018

Electron channeling contrast imaging (ECCI) is one of the imaging techniques in scanning electron microscopy based on a variation in electron backscattering yield depending on the direction of the primary electron beam with respect to the crystal lattice. The ECCI provides not only observation of the distribution of individual grains and grain boundaries but also identification of the defects such as dislocations, twins, and stacking faults. The ECCI at the interface between recrystallized and deformed region of shot peening treated nickel clearly demonstrates the microstructural evolution during the recrystallization including original grain boundaries, and thus can provide better insight into the recrystallization behavior.

• Asian Pacific Journal of Cancer Prevention
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• 제16권15호
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• pp.6765-6768
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• 2015

Aims: To study the effectiveness of human recombinant endostatin injection (Endostar(R)) combined with cisplatin doublets in treating advanced non-small cell lung cancer (NSCLC), and to evaluate outcome by CT perfusion imaging. Methods: From April 2011 to September 2014, 76 patients with advanced NSCLC who were treated with platinum-based doublets were divided into group A (36 patients) and group B (40 patients). Endostar(R) 15mg/day was administered 4 days before chemotherapy and combined with chemotherapy from day 5 in group A, and combined with chemotherapy from the first day in Group B. Endostar(R) in the two groups was injected intravenously for 14 days. Results: Treatment effectiveness in the two groups differed with statistical significance (p<0.05). Effectiveness evaluated by CT perfusion imaging, BF, BV, MTT and PS also demonstrated significant differences (all p<0.05). Adverse reactions in the two groups did not significantly vary (p> 0.05). Conclusions: The response rate with Endostar(R) administered 4 days before chemotherapy and combined with chemotherapy from day 5 in group A was better than Endostar(R) combined with chemotherapy from the first day, and CT perfusion imaging could be a reasonable method for evaluation of patient outcomes.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제20권3호
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• pp.175-202
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• 2016

Ultrasound imaging is a widely used tool for visualizing human body's internal organs and quantifying clinical parameters. Due to its advantages such as safety, non-invasiveness, portability, low cost and real-time 2D/3D imaging, diagnostic ultrasound industry has steadily grown. Since the technology advancements such as digital beam-forming, Doppler ultrasound, real-time 3D imaging and automated diagnosis techniques, there are still a lot of demands for image quality improvement, faster and accurate imaging, 3D color Doppler imaging and advanced functional imaging modes. In order to satisfy those demands, mathematics should be used properly and effectively in ultrasound imaging. Mathematics has been used commonly as mathematical modelling, numerical solutions and visualization, combined with science and engineering. In this article, we describe a brief history of ultrasound imaging, its basic principle, its applications in obstetrics/gynecology, cardiology and radiology, domestic-industrial products, contributions of mathematics and challenging issues in ultrasound imaging.

• Nuclear Medicine and Molecular Imaging
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• 제43권3호
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• pp.165-173
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• 2009

Nuclear cardiology in Korea is less active, compared to nuclear oncology, but it has been specialized and ramified. Lately, sophisticated nuclear cardiac imaging methods provide more convenience for patients. It is necessary to accurately estimate the recent progress in the imaging devices for nuclear cardiology. Myocardial perfusion imaging is a well established study to evaluate heart function. Myocardial perfusion SPECT and PET have been used for assessment of coronary artery disease with various radiopharmaceuticals. And of late, the development of advanced imaging devices - multi-pinhole technique and high definition imaging technique - and software made the scanning time shorter and expanded the application field. Therefore, it is required to review the nuclear cardiology hardware/software for the clinical practice and research. In this review, the characteristics about recently-developed SPECT/PET and software for nuclear cardiology are described. It is hoped that this information would contribute to improving the activity of nuclear cardiac research in Korea where the research for the fusion imaging combining a and nuclear imaging is drawing more attention.

• Applied Microscopy
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• 제46권1호
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• pp.6-13
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• 2016

Fluorescence lifetime imaging microscopy (FLIM) has been considered an effective technique to investigate chemical properties of the specimens, especially of biological samples. Despite of this advantageous trait, researchers in this field have had difficulties applying FLIM to their systems because acquiring an image using FLIM consumes too much time. Although analog mean-delay (AMD) method was introduced to enhance the imaging speed of commonly used FLIM based on time-correlated single photon counting (TCSPC), a real-time image reconstruction using AMD method has not been implemented due to its data processing obstacles. In this paper, we introduce a real-time image restoration of AMD-FLIM through fast parallel data processing by using Threading Building Blocks (TBB; Intel) and octa-core processor (i7-5960x; Intel). Frame rate of 3.8 frames per second was achieved in $1,024{\times}1,024$ resolution with over 4 million lifetime determinations per second and measurement error within 10%. This image acquisition speed is 184 times faster than that of single-channel TCSPC and 9.2 times faster than that of 8-channel TCSPC (state-of-art photon counting rate of 80 million counts per second) with the same lifetime accuracy of 10% and the same pixel resolution.

• Investigative Magnetic Resonance Imaging
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• 제23권1호
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• pp.1-16
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• 2019

Dynamic contrast enhanced (DCE) magnetic resonance (MR) imaging plays an important role in non-invasive detection and characterization of primary and metastatic lesions in the liver. Recently, efforts have been made to improve spatial and temporal resolution of DCE liver MRI for arterial phase imaging. Review of recent publications related to arterial phase imaging of the liver indicates that there exist primarily two approaches: breath-hold and free-breathing. For breath-hold imaging, acquiring multiple arterial phase images in a breath-hold is the preferred approach over conventional single-phase imaging. For free-breathing imaging, a combination of three-dimensional (3D) stack-of-stars golden-angle sampling and compressed sensing parallel imaging reconstruction is one of emerging techniques. Self-gating can be used to decrease respiratory motion artifact. This article introduces recent MRI technologies relevant to hepatic arterial phase imaging, including differential subsampling with Cartesian ordering (DISCO), golden-angle radial sparse parallel (GRASP), and X-D GRASP. This article also describes techniques related to dynamic 3D image reconstruction of the liver from golden-angle stack-of-stars data.

• Imaging Science in Dentistry
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• 제50권4호
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• pp.273-279
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• 2020

This review presents an overview of some diagnostic imaging-related issues regarding medication-related osteonecrosis of the jaws(MRONJ), including imaging signs that can predict MRONJ in patients taking antiresorptive drugs, the early imaging features of MRONJ, the relationship between the presence or absence of bone exposure and imaging features, and differences in imaging features by stage, between advanced MRONJ and conventional osteomyelitis, between oncologic and osteoporotic patients with MRONJ, and depending on the type of medication, method of administration, and duration of medication. The early diagnosis of MRONJ can be made by the presence of subtle imaging changes such as thickening of the lamina dura or cortical bone, not by the presence of bone exposure. Most of the imaging features are relatively non-specific, and each patient's clinical findings and history should be referenced. Oral and maxillofacial radiologists and dentists should closely monitor plain radiographs of patients taking antiresorptive/antiangiogenic drugs.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2012년도 춘계 종합학술대회 논문집
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• pp.323-324
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• 2012

유아기는 인간의 삶은 중요한 영향을 준다. 이러한 유아들을 위해 교육법과 교육소재들이 있다. 교육소재는 교육법이 추구하는 인간상을 위해 교육적인 내용과 간접경험을 제공한다. 본 논문은 교육소재를 개발하여 경험을 제공하고 발상력과 창의력을 키운다.

• Imaging Science in Dentistry
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• 제51권2호
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• pp.107-115
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• 2021

Purpose: This study aimed to demonstrate the presence of dental caries through a photoacoustic imaging system with visible and near-infrared wavelengths, highlighting the differences between the 2 spectral regions. The depth at which carious tissue could be detected was also verified. Materials and Methods: Fifteen permanent molars were selected and classified as being sound or having incipient or advanced caries by visual inspection, radiography, and optical coherence tomography analysis prior to photoacoustic scanning. A photoacoustic imaging system operating with a nanosecond pulsed laser as the light excitation source at either 532 nm or 1064 nm and an acoustic transducer at 5 MHz was developed, characterized, and used. En-face and lateral(depth) photoacoustic signals were detected. Results: The results confirmed the potential of the photoacoustic method to detect caries. At both wavelengths, photoacoustic imaging effectively detected incipient and advanced caries. The reconstructed photoacoustic images confirmed that a higher intensity of the photoacoustic signal could be observed in regions with lesions, while sound surfaces showed much less photoacoustic signal. Photoacoustic signals at depths up to 4 mm at both 532 nm and 1064 nm were measured. Conclusion: The results presented here are promising and corroborate that photoacoustic imaging can be applied as a diagnostic tool in caries research. New studies should focus on developing a clinical model of photoacoustic imaging applications in dentistry, including soft tissues. The use of inexpensive light-emitting diodes together with a miniaturized detector will make photoacoustic imaging systems more flexible, user-friendly, and technologically viable.