• Biomedical Engineering Letters
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• 제8권4호
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• pp.383-392
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• 2018

For prompt gamma ray imaging for biomedical applications and environmental radiation monitoring, we propose herein a multiple-scattering Compton camera (MSCC). MSCC consists of three or more semiconductor layers with good energy resolution, and has potential for simultaneous detection and differentiation of multiple radio-isotopes based on the measured energies, as well as three-dimensional (3D) imaging of the radio-isotope distribution. In this study, we developed an analytic simulator and a 3D image generator for a MSCC, including the physical models of the radiation source emission and detection processes that can be utilized for geometry and performance prediction prior to the construction of a real system. The analytic simulator for a MSCC records coincidence detections of successive interactions in multiple detector layers. In the successive interaction processes, the emission direction of the incident gamma ray, the scattering angle, and the changed traveling path after the Compton scattering interaction in each detector, were determined by a conical surface uniform random number generator (RNG), and by a Klein-Nishina RNG. The 3D image generator has two functions: the recovery of the initial source energy spectrum and the 3D spatial distribution of the source. We evaluated the analytic simulator and image generator with two different energetic point radiation sources (Cs-137 and Co-60) and with an MSCC comprising three detector layers. The recovered initial energies of the incident radiations were well differentiated from the generated MSCC events. Correspondingly, we could obtain a multi-tracer image that combined the two differentiated images. The developed analytic simulator in this study emulated the randomness of the detection process of a multiple-scattering Compton camera, including the inherent degradation factors of the detectors, such as the limited spatial and energy resolutions. The Doppler-broadening effect owing to the momentum distribution of electrons in Compton scattering was not considered in the detection process because most interested isotopes for biomedical and environmental applications have high energies that are less sensitive to Doppler broadening. The analytic simulator and image generator for MSCC can be utilized to determine the optimal geometrical parameters, such as the distances between detectors and detector size, thus affecting the imaging performance of the Compton camera prior to the development of a real system.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권5호
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• pp.579-587
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• 2014

This paper presents a variable gain amplifier (VGA) for an analog front-end (AFE) of ultrasound medical imaging. This VGA has a closed-loop topology and shows a 37-dB-linear characteristic with a single-stage amplifier. It consists of an op-amp, a non-binary-weighted capacitor array, and a gain-control block. This non-binary-weighted capacitor array reduces the required number of capacitors and the complexity of the gain-control block. The VGA has been fabricated in a 0.35-mm CMOS process. This work gives the largest gain range of 37 dB per stage, the largest P1 dB of 9.5 dBm at the 3.3-V among the recent VGA circuits available in the literature. The voltage gain is controlled in the range of [-10, 27] dB in a linear-in-dB scale with 16 steps by a 4-bit digital code. The VGA has a bandpass characteristic with a passband of [20 kHz, 8 MHz].

• Current Optics and Photonics
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• 제2권5호
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• pp.460-467
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• 2018

Three-dimensional (3D) refractive-index (RI) imaging and quantitative analyses of angiosperm pollen grains are presented. Using optical diffraction tomography, the 3D RI structures of individual angiosperm pollen grains were measured without using labeling or other preparation techniques. Various physical quantities including volume, surface area, exine volume, and sphericity were determined from the measured RI tomograms of pollen grains. Exine skeletons, the distinct internal structures of angiosperm pollen grains, were identified and systematically analyzed.

• 한국정밀공학회지
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• 제26권12호
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• pp.138-145
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• 2009

Custom medical treatment is being widely adapted to lots of medical applications. A technology for 3D modeling is strongly required to fabricate medical implants for individual patient. Needs on true 3D CAD data of a patient is strongly required for tissue engineering and human body simulations. Medical imaging devices show human inner section and 3D volume rendering images of human organs. CT or MRI is one of the popular imaging devices for that use. However, those image data is not sufficient to use for medical fabrication or simulation. This paper mainly deals how to generate 3D geometry data from those medical images. A new image processing technology is introduced to reconstruct 3D geometry of a human body vacancy from the medical images. Then a surface geometry data is reconstructed by using Marching cube algorithm. Resulting CAD data is a custom 3D geometry data of human vacancy. This paper introduces a novel 3D reconstruction process and shows some typical examples with implemented software.

• Imaging Science in Dentistry
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• 제53권4호
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• pp.283-289
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• 2023

The apnea-hypopnea index is widely regarded as a measure of the severity of obstructive sleep apnea (OSA), a condition characterized by recurrent episodes of apnea or hypopnea during sleep that induce airway collapse. OSA is a catastrophic problem due to the wide range of health issues it can cause, including cardiovascular disease and memory loss. This review was conducted to clarify the roles of various imaging modalities, particularly cone-beam computed tomography (CBCT), in the diagnosis of and preoperative planning for OSA. Unfortunately, 2-dimensional imaging techniques yield insufficient data for a comprehensive diagnosis, given the complex anatomy of the airway. Three-dimensional (3D) imaging is favored as it more accurately represents the patient's airway structure. Although computed tomography and magnetic resonance imaging can depict the actual 3D airway architecture, their use is limited by factors such as high radiation dose and noise associated with the scans. This review indicates that CBCT is a low-radiation imaging technique that can be used to incidentally identify patients with OSA, thereby facilitating early referral and ultimately enhancing the accuracy of surgical outcome predictions.

• 지구물리와물리탐사
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• 제5권3호
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• pp.145-149
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• 2002

정보정은 풍화층의 두께나 속도가 균질하지 않아 하부의 지층으로부터 전파된 신호의 왜곡을 보정하는 방법으로 굴절파에 근거한 정보정과 반사파에 근거한 잔여 정보정이 있다. 이 중 굴절파에 근거한 정보정은 일반적으로 분석자의 주관적인 해석에 의존하므로 많은 시간이 소요된다. 따라서 방대한 양의 자료를 처리해야하는 3차원 탄성파 탐사 자료의 정보정에 적용하는 데는 어려움이 있다. 이러한 굴절파에 근거한 정보정을 적용하기 위해서는 분석자의 해석을 최소한으로 하여 자동적으로 정보정을 수행하는 방법의 개발이 필요다. 본 연구에서는 굴절파에 근거한 정보정 방법을 육상 3차원 탄성파 탐사 자료에 대해 효과적으로 수행할 수 있는 방법에 대해 살펴보았다.

• Journal of KIEE
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• 제10권1호
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• pp.1-6
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• 2000

This paper represents the design of 3D endoscopic video system in order to improve visualization and enhance the ability of the surgeon to perform delicate endoscopic surgery. In comparison of the polarized and electric shutter-type stereo imaging system, The former is superior in terms of accuracy and performance speed for knot-tying and loop pass test. The result of experiments show that the proposed 3D endoscopy system has a wide viewing angle and zone which is necessary for multi-view and it has better image quality and stability of the optical performances than the electric shutter-type does.

• 천문학회보
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• 제43권2호
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• pp.32.3-32.3
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• 2018

We use the synthetic light-cone from the cosmological hydrodynamical simulation Horizon-AGN to produce a mock photometric galaxy catalogue on the redshift range 0

• 대한방사선기술학회지:방사선기술과학
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• 제30권2호
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• pp.177-180
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• 2007

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.557-561
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• 2009

This paper presents a prototype of high resolution 3D display with a new principle. We have proposed a new 3D display which has the features of both Integral Imaging (II) and volumetric display. The proposed display consists of two lens arrays and a thin volumetric display. When the viewer watches a thin volumetric display through two lens array, he can perceive a thick 3D image. In other words the two lens arrays can play a role of a convex lens which has a large diameter as a amplification of a depth. The advantage of the proposed display is that it has higher resolution than II and it is smaller than volumetric display with a large convex lens. In this paper, we show a detail of a prototype 3D display. We took various errors into consideration when we simulated 3D display and we found suitable lenses parameter from the simulation result. Then we confirm that the prototype will be able to reconstruct 3D images.