• Neurospine
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• 제15권4호
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• pp.306-322
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• 2018

This review introduces the current technique of photoacoustic imaging as it is applied in imaging-guided surgery (IGS), which provides the surgeon with image visualization and analysis capabilities during surgery. Numerous imaging techniques have been developed to help surgeons perform complex operations more safely and quickly. Although surgeons typically use these kinds of images to visualize targets hidden by bone and other tissues, it is nonetheless more difficult to perform surgery with static reference images (e.g., computed tomography scans and magnetic resonance images) of internal structures. Photoacoustic imaging could enable real-time visualization of regions of interest during surgery. Several researchers have shown that photoacoustic imaging has potential for the noninvasive diagnosis of various types of tissues, including bone. Previous studies of the surgical application of photoacoustic imaging have focused on cancer surgery, but photoacoustic imaging has also recently attracted interest for spinal surgery, because it could be useful for avoiding pedicle breaches and for choosing an appropriate starting point before drilling or pedicle probe insertion. This review describes the current instruments and clinical applications of photoacoustic imaging. Its primary objective is to provide a comprehensive overview of photoacoustic IGS in spinal surgery.

• 방송공학회논문지
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• 제8권1호
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• pp.63-71
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• 2003

실시간 가상이미징 시스템은 스포츠 중계 방송에서 팀의 문양이나 점수, 거리와 같은 정보를 실제 운동장 위에 합성해 줌으로써, 일반적인 자막기의 단점을 보완할 수 있는 새로운 기술로 주목받고 있다. 카메라의 움직임에 그래픽을 정확히 연동시키기 위해서는 카메라의 각 축에 센서를 장착하는 방식과 실제 카메라 영상 자체를 분석하는 방식이 사용된다. KBS 기술연구소에서는 방송용 렌즈 기 줌(zoom), 포커스(focus) 부와 팬(Pan), 틸트(tilt) 축에 센서를 부착하여, 실시간으로 3차원 그래픽의 가상 카메라를 제어하는 센서기반 가상이미징 시스템 'VIVA'를 개발하였다. 본 논문에서는 VIVA 시스템과 그 구현 기술을 소개하고자 한다. 정확한 카메라 추적을 위하여 주밍(zooming)시 발생하는 카메라 시점(view-point)의 이동을 렌즈의 광학주점 변이 데이터를 이용하여 계산하였으며, 줌 뿐만 아니라 포커스에 따른 화각 변화를 반영하였다. 3차원 그래픽에 기반하여 가상 이미징 시스템을 구현함으로써, 키프레임(keyframe) 애니메이션과 같은 유용한 그래픽 기술이 사용될 수 있도록 하였다. VIVA는 2002년 부산 아시안게임과 대선 개표 방송에 사용되어, 스포츠 프로그램뿐만 아니라 근거리 촬영이 요구되는 스튜디오 프로그램 제작에도 사용이 가능함을 확인하였다.

• 정보처리학회논문지B
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• 제13B권3호
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• pp.295-300
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• 2006

집적 영상(Integral Imaging) 시스템은 사용자가 특수 안경을 착용하지 않고 3차원 입체영상을 볼 수 있도록 해주는 무안경식 양안시차 디스플레이 방식 중 한가지이다. 집적 영상 시스템은 3차원 정보를 조금씩 다른 방향에서 제한된 크기로 촬영된 이미지인 기초영상(Elemental Image)의 형태로 저장한다. 그리고 이런 이미지들을 다시 렌즈 어레이를 통해서 보여주어 사용자들로 하여금 3차원 정보를 얻을 수 있도록 한다. 이런 기초영상은 컴퓨터 그래픽을 이용해서 만들어낼 수도 있는데 이런 집적 영상 방식을 CG(Computer Generated) 집적 영상 시스템이라고 한다. 그리고 컴퓨터를 이용해 기초영상을 만드는 과정을 이미지 매핑(Image Mapping)이라고 한다. 이제까지 제안된 이미지 매핑 방식에는 PRR(Point Retracing Rendering), MVR(Multi-Viewpoint Rendering), PGR(Parallel Group Rendering) 등이 있다. 그러나 이런 방식들은 계산양이 많거나 렌즈 어레이 개수의 증가에 의해 생성 속도에 영향을 받는 단점이 있어, 아직 가상현실 같은 실시간 CG(Computer Graphics) 응용 분야에서 사용하기 어려운 문제가 있다. 따라서 본 논문에서는 기존의 방법에 비해 속도 향상을 이룬 VVR(Viewpoint Vector Rendering)이라는 향상된 이미지 매핑 방법을 제안한다. 먼저 VVR 개념을 설명한 후 VVR을 사용한 집적 영상 시스템을 구현하여 MVR 방법과 비교 분석한 실험결과와 추후 개선되어야 할 방향을 제시한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.3207-3209
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• 2000

X-ray CT(Computed Tomography) has been a good modality for non-invasive diagnosis and recently, Conventional CT has been replaced rapidly with Spiral CT in recent. In X-ray CT, spiral scanning has various advantages such as better image quality, reduced scan time (in a single breath-hold), a lower x-ray dose. But, it requires very fast and high performance image processing system to reconstruct slice images from spiral scanning. This paper describes the fast image reconstruction techniques with filtered back projection from the viewpoints of fast algorithm as well as hardware implementation for real-time imaging.

• 비파괴검사학회지
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• 제28권2호
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• pp.101-111
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• 2008

의료용 초음파 영상 시스템에서 스트레인 영상 기법은 병변 주위의 조직보다 단단한 성질을 가지는 암이나 종양을 영상화할 수 있다. 준정적인 압축(quasistatic compression) 방법을 이용하여 스트레인 영상을 얻는 방법은, 조직에 변형을 가하기 전의 초음파 신호를 기준으로 하여 변형을 가한 후에 얻어진 초음파 신호 사이의 변위를 계산하고, 이를 공간 미분하여 스트레인을 구한다. 본 논문에서 변위의 계산은 복소 기저대역 신호의 자기상관(autocorrelation)을 계산하여 위상차로부터 구하고, 위상차를 시간 혹은 거리로 변환할 때 발생하는 오차를 중심주파수 편차를 보상하여 줄였다. 조작자의 손 움직임의 영향을 줄이기 위해 모든 스캔라인의 변위를 정규화시키는 알고리즘을 적용하여 균일한 스트레인 영상을 얻었다. 제안한 스트레인 영상 기법을 초음파 영상 진단기에서 실시간 동작하도록 구현하였다.

• International Journal of Internet, Broadcasting and Communication
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• 제14권2호
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• pp.10-16
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• 2022

As an important part of virtual production, In-camera VFX is the process of shooting actual objects and virtual three-dimensional backgrounds in real-time through computer graphics technology and display technology, and obtaining the final film. In the In-camera VFX process, there are currently only two types of medium used to undertake background imaging, LED wall and chroma key screen. Among them, the In-camera VFX based on LED wall realizes background imaging through LED display technology. Although the imaging quality is guaranteed, the high cost of LED wall increases the cost of virtual production. The In-camera VFX based on chroma key screen, the background imaging is realized by real-time keying technology. Although the price is low, due to the limitation of real-time keying technology and lighting conditions, the usability of the final picture is not high. The short-throw projection technology can compress the projection distance to within 1 meter and get a relatively large picture, which solves the problem of traditional projection technology that must leaving a certain space between screen and the projector, and its price is relatively cheap compared to the LED wall. Therefore, in the In-camera VFX process, short-throw projection technology can be tried to project backgrounds. This paper will analyze the principle of short-throw projection technology and the existing In-camera VFX solutions, and through the comparison experiments, propose a low-cost solution that uses short-throw projectors to project virtual backgrounds and realize the In-camera VFX process.

• Journal of Chest Surgery
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• 제52권4호
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• pp.205-220
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• 2019

Near-infrared (NIR) fluorescence imaging provides a safe and cost-efficient method for immediate data acquisition and visualization of tissues, with technical advantages including minimal autofluorescence, reduced photon absorption, and low scattering in tissue. In this review, we introduce recent advances in NIR fluorescence imaging systems for thoracic surgery that improve the identification of vital tissues and facilitate the resection of tumorous tissues. When coupled with appropriate NIR fluorophores, NIR fluorescence imaging may transform current intraoperative thoracic surgery methods by enhancing the precision of surgical procedures and augmenting postoperative outcomes through improvements in diagnostic accuracy and reductions in the remission rate.

• Smart Structures and Systems
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• 제8권3호
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• pp.303-320
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• 2011

Comparing to active damage monitoring, impact localization on composite by using time reversal focusing method has several difficulties. First, the transfer function of the actuator-sensor path is difficult to be obtained because of the limitation that no impact experiment is permitted to perform on the real structure and the difficulty to model it because the performance of real aircraft composite is much more complicated comparing to metal structure. Second, the position of impact is unknown and can not be controlled as the excitation signal used in the active monitoring. This makes it not applicable to compare the difference between the excitation and the focused signal. Another difficulty is that impact signal is frequency broadband, giving rise to the difficulty to process virtual synthesis because of the highly dispersion nature of frequency broadband Lamb wave in plate-like structure. Aiming at developing a practical method for on-line localization of impact on aircraft composite structure which can take advantage of time reversal focusing and does not rely on the transfer function, a PZT sensor array based phase synthesis time reversal impact imaging method is proposed. The complex Shannon wavelet transform is presented to extract the frequency narrow-band signals from the impact responded signals of PZT sensors. A phase synthesis process of the frequency narrow-band signals is implemented to search the time reversal focusing position on the structure which represents the impact position. Evaluation experiments on a carbon fiber composite structure show that the proposed method realizes the impact imaging and localization with an error less than 1.5 cm. Discussion of the influence of velocity errors and measurement noise is also given in detail.

• 상하수도학회지
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• 제38권2호
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• pp.109-117
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• 2024

In this study, various pre-treatment methods were evaluated for microalgae separation. These methods aimed to facilitate safe, rapid, and cost-effective online imaging for real-time observation and cell counting. As pre-treatment techniques, heating, chemical hydrolysis, heating combined with chemical hydrolysis, and sonication were employed. The effectiveness of these methods was evaluated in the context of online imaging quality through experimentation on cultivated microalgae (Chlorella vulgaris and Scenedesmus quadricauda). The chemical treatment method was found to be inappropriate for improving image acquisition. The heating pre-treatment method exhibited a drawback of prolonged cell dispersion time. Additionally, the heating combined with chemical hydrolysis method was confirmed to have the lowest dispersion effect for Chlorella vulgaris. Conversely, ultrasonication emerged as a promising technique for microalgae separation in terms of repeatability and reproducibility. This study suggests the potential for selecting optimal pre-treatment methods to effectively operate real-time online monitoring devices, paving the way for future research and applications in microalgae cultivation and imaging.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.85.2-85.2
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• 2016

With the advent of ultra-short high-intense XFEL (X-ray Free Electron Laser), time-resolved dynamics has become of great importance in exploring femtosecond real-world phenomena of nanoscience and biology. These include studying the response of materials to femtosecond laser excitation and investigating the interaction of XFEL itself with condensed matter. A variety of dynamic phenomena have been investigated such as radiation damage, ultrafast melting process, non-equilibrium phase transitions caused by orbital-lattice-spin couplings. As far as bulk materials are concerned, the sample size has no effect on the following dynamic process. As a result, imaging information is not required by and large. If the sample size is of tens of nanometers, however, sample starts to experience quantum confinement effect which, in turn, affects the following dynamic process. Therefore, to understand the fundamental dynamic phenomena in nano-science, time-resolved imaging information is essential. In this talk, we will briefly introduce scientific highlights achieved in XFEL-based dynamics. In case of bio-imaging, recent scientific topics will be mentioned as well. Finally, we will aim to present feasible topics in ultrafast time-resolved imaging and to discuss the future plan of CXI beamline at PAL-XFEL.