• Journal of Korean Neurosurgical Society
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• 제47권6호
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• pp.437-441
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• 2010

Objective : The precise intra- vs. extradural localization of aneurysms involving the paraclinoid internal carotid artery is critical for the evaluation of patients being considered for aneurysm surgery. The purpose of this study was to investigate the clinical usefulness of T2-weighted threedimensional (3-D) fast spin-echo (FSE) magnetic resonance (MR) imaging in the evaluation of unruptured paraclinoid aneurysms. Methods : Twenty-eight patients with unruptured cerebral aneurysms in their paraclinoid regions were prospectively evaluated using a T2- weighted 3-D FSE MR imaging technique with oblique coronal sections. The MR images were assessed for the location of the cerebral aneurysm in relation to the dural ring and other surrounding anatomic compartments, and were also compared with the surgical or angiographic findings. Results : All 28 aneurysms were identified by T2-weighted 3D FSE MR imaging, which showed the precise anatomic relationships in regards to the subarachnoid space and the surrounding anatomic structures. Consequently, 13 aneurysms were determined to be intradural and the other 15 were deemed extradural as they were confined to the cavernous sinus. Of the 13 aneurysms with intradural locations, three superior hypophyseal artery aneurysms were found to be situated intradurally upon operation. Conclusion : High-resolution T2-weighted 3-D FSE MR imaging is capable of confirming whether a cerebral aneurysm at the paraclinoid region is intradural or extradural, because of the MR imaging's high spatial resolution. The images may help in identifying patients with intradural aneurysms who require treatment, and they also can provide valuable information in the treatment plan for paraclinoid aneurysms.

• Current Optics and Photonics
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• 제8권5호
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• pp.484-492
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• 2024

In response to the difficulty of synchronously obtaining multiwavelength images for fast two-dimensional (2D) temperature measurement, a multispectral framing imaging optical system is designed, based on the segmented-aperture imaging method and asymmetric surface shape. The system adopts a common-aperture four-channel array structure to synchronously collect multiwavelength temperature-field images. To solve the problem of asymmetric aberration caused by being off-axis, a model of the relationship between incident and outgoing rays is established to calculate the asymmetric custom surface. The designed focal length of the optical system is 80 mm, the F-number is 1:3.8, and the operating wavelength range is 0.48-0.65 ㎛. The system is divided into four channels, corresponding to wavelengths of 0.48, 0.55, 0.58, and 0.65 ㎛ respectively. The modulation transfer function value of a single channel lens is higher than 0.6 in the full field of view at 35 lp/mm. The experimental results show that the asymmetric-custom-surface imaging system can capture clear multiwavelength images of a temperature field. The framing imaging system can capture clear images of multiwavelength temperature fields, with high consistency in images of different wavelengths. The designed optical system can provide reliable multiwavelength image data for 2D temperature-field measurement.

• 지구물리와물리탐사
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• 제11권4호
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• pp.302-309
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• 2008

3차원 전기비저항 토모그래피는 토목 및 수리지질분야 등에서 매우 고분해능의 지하구조 영상을 획득할 수 있는 강력한 성능을 제공한다. 이 논문에서는 특히 3차원 이상대가 주탐사 대상인 경우에 대한 3차원 전기비저항 토모그래피의 두가지 성공적 응용사례를 소개한다. 첫번째 예는 수리지질분야에의 응용을 위한 파쇄대 영상화 사례로서, 여기서는 시추공의 공곡변화가 중요한 문제로 대두되었으며 이에 따라 시추공 공곡변화를 토모그래피 역산과정에 포함함으로써 파쇄대의 3차원 영상을 획득할 수 있었다. 두번째 예에서는 크기 $2m{\times}2m$의 내부가 비어있는 터널의 영상화 문제를 다루었으며, 3차원 토모그래피를 통하여 터널의 발달을 3차원 공간상에 영상화할 수 있었다. 이들 예로부터 3차원 전기비저항 토모그래피가 3차원 지하구조 영상화에 강력한 성능을 보임과 아울러 특히 3차원 이상대인 파쇄대, 공동 또는 터널의 영상화에 더욱 향상된 영상화 능력을 제공할 수 있음을 보였다.

• 한국광학회:학술대회논문집
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• 한국광학회 2009년도 창립 20주년기념 특별학술발표회
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• pp.6-7
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• 2009

We proposed the two-dimensional (2D) / three-dimensional (3D) convertible modified integral imaging system using functional polarizing film named $imazer^{TM}$, which transfer or scatter the incident light ray according to the polarizing direction of ray. When the incident light rays transfer to $imazer^{TM}$, the rays generate 3D image through the process of the modified integral imaging system. However, the scattered light rays generate 2D image through the simple backlight scheme when the incident rays are scattered by the film. The proposed method can be implemented the partial 3D display system without any mechanical movements. In this paper, we propose and verify our system using some basic experiments and its results.

• 대한의용생체공학회:의공학회지
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• 제33권2호
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• pp.72-77
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• 2012

Phase Contrast MR Angiography(PC MRA) is excellent MRA technique for measuring the velocity of vessels in the human body. PC MRA need to at least four images for angiogram reconstruction and it caused longer scan time. Therefore, we used keyhole imaging combined PC MRA to reduce the scan time. However, keyhole imaging can lead the erroneous effects as loss of phase information or frequency discontinuous. In this study, we applied the keyhole imaging combined 2D PC MRA for improving the temporal resolution and also measured the velocity to evaluate the accuracy of phase information. We used 0.32T MRI scanner(Magfinder II, Scimedix, Korea). Using the 2D PC MRA pulse sequence, the vascular images for a human brain targeted on the Superior Sagittal Sinus(SSS) were obtained. We applied tukey window function for keyhole images to minimize the ringing artifact and erroneous factors that are induced frequency discontinuous and phase information loss. We also applied zero-padded algorithm to peripheral missing k-space lines to compare keyhole imaging results and the artifact power(AP) value was measured on the complex difference images to validate the image quality. Consider as based on our results, heavy image distortions and artifacts were shown until using at least 50% keyhole factor. Using above the 50% keyhole factors are shown well reconstructed and matched for magnitude images and velocity information measurements. In conclusion, we confirmed the image quality and velocity information of keyhole technique combined 2D PC MRA. Especially, measured velocity information through the keyhole imaging combination was similar to the velocity information of full sampled k-space image despite of frequency discontinuous and phase information loss in the keyhole imaging reconstruction process. Consequently, the keyhole imaging combined 2D PC MRA will give some clinical usefulness and advantages as improving the temporal resolution and measuring the velocity information via selecting the appropriate keyhole factor at low tesla MRI system.

• Journal of Cardiovascular Imaging
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• 제30권4호
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• pp.279-289
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• 2022

BACKGROUND: In many cardiovascular disorders, the contractile performance of the right ventricle (RV) is the primary determinant of prognosis. For evaluating RV volumes and function, 4 dimensional (4D)-echocardiography has become common. This research used 2D and 4D modalities to assess RV contractile performance in hypertensive patients. METHODS: A total of 150 patients with essential hypertension were enrolled in this study, along with 75 age and sex-matched volunteers. Clinical evaluation and echocardiographic examination (including M-mode, tissue Doppler imaging, and 2D speckle tracking) were conducted on all participants. RV volumes, 4D-ejection fraction (EF), 4D-fractional area change (FAC), 4D-tricuspid annular plane systolic excursion (TAPSE), 4D-septal and free wall (FW) strain were all measured using 4D-echocardiography. RESULTS: Hypertensive patients showed 2D-RV systolic and diastolic dysfunction (including TAPSE, 2D-right ventricular global longitudinal strain, RV-myocardial performance index and average E/EaRV) and 4D-RV impairment (including right ventricular EF, FAC, RV strain and TAPSE, right ventricular end-diastolic volume and right ventricular end-systolic volume) compared to the control group. We verified the prevalence of RV systolic dysfunction in hypertension patients using the following parameters: 1) 15% of them had 2D-TAPSE < 17 mm vs. 40% by 4D-TAPSE; 2) 25% of them had 2D-GLS < 19% vs. 42% by 4D-septal strain and 35% by 4D FW strain; 3) 35% of hypertensive patients had 4D-EF < 45%; and finally; 4) 25% of hypertensive patients had 2D-FAC < 35% compared to 45% by 4D-FAC. CONCLUSIONS: The incidence of RV involvement was greater in 4D than in 2D-modality trans-thoracic echocardiography. We speculated that 4D-echocardiography with 4D-strain imaging would be more beneficial for examining RV morphology and function in hypertensive patients than 2D-echocardiography, since 4D-echocardiography could estimate RV volumes and function without making geometric assumptions.

• 한국정보통신학회논문지
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• 제20권7호
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• pp.1369-1375
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• 2016

본 논문에서는 요소 영상간의 상관관계를 위상필터를 이용하여 구하고 집적 영상 기술에서 이를 활용하여 깊이정보를 추출하는 시스템을 제안한다. 집적 영상 기술은 수동 광원을 사용하여 렌즈 배열을 통해 3차원 물체의 광선정보를 2차원 영상 획득 장치로 기록하고 이를 동일한 렌즈 배열을 통해 3차원 영상을 디스플레이 하는 3차원 영상 시스템 기술이다. 렌즈 배열을 통해 획득된 2차원 영상들은 서로 다른 원근감을 가지는 요소 영상이다. 이 영상들과 물체와의 상관관계를 구하여 깊이정보를 추출할 수 있다. 그리고 요소 영상으로 컴퓨터 재생을 하여 다시 필터를 이용한 상관관계를 구하게 되면 더욱 정확한 깊이정보를 얻을 수 있다. 본 논문에서는 제안된 기술을 검증하기 위해 광학적 실험을 수행하고 상관관계의 지표로써 Peak Side lobe Ratio (PSR)을 구하였다.

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.179-183
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• 2002

Resonance-enhanced multiphoton ionization with time-of-flight product imaging of the $N(^2D)$ atoms has been used to study the $N_2O$ photodissociation at 118.2 nm and the two-photon dissociation at 268.9 nm. These imaging experiments allowed the determination of the total kinetic energy distribution of the $NO(X^2{\prod})$ and $N(^2D_{5/2})$ products. The $NO(X^2{\prod})$ fragments resulting from the photodissociation processes are produced in highly vibrationally excited states. The two-photon photodissociation process yields a broad $NO(X^2{\prod})$ vibrational energy distribution, while the 118.2 nm dissociation appears to produce a vibrational distribution sharply peaked at $NO(X^2{\prod},\;{\nu}=14)$.

• 대한디지털의료영상학회논문지
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• 제5권1호
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• pp.26-31
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• 2002

본 연구의 목적은 복강경 수술환경에서 2D와 3D 내시경 비디오 영상이 수술에 미치는 영향을 평가하기 위한 연구이며, 이를 위해 3D 내시경 시스템을 구성하고 성능 평가를 수행하였다. 결과적으로 본 연구에서 제안한 3D 방식이 기존의 전자셔터 방식에 의한 3D 영상에 비해 화질과 시야각이 우수하며, 2종류의 모의 수술 실험 비교를 한 결과, 제안한 방식의 디지털 영상을 이용하는 경우가 성능이 가장 우수함을 정량적으로 확인하였다.

• Journal of the Optical Society of Korea
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• 제12권2호
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• pp.98-102
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• 2008

Optical Coherence Tomography (OCT) is an important noninvasive medical imaging technique that can reveal subsurface structures of biological tissue. OCT has demonstrated a good correlation with histology in sufficient resolution to identify morphological changes in articular cartilage to differentiate normal through progressive stages of degenerative joint disease. Current OCT systems provide individual cross-sectional images that are representative of the tissue directly under the scanning beam, but they may not fully demonstrate the degree of degeneration occurring within a region of a joint surface. For a full understanding of the nature and degree of cartilage degeneration within a joint, multiple OCT images must be obtained and an overall assessment of the joint surmised from multiple individual images. This study presents frequency domain three-dimensional (3-D) OCT imaging of degenerative joint cartilage extracted from bovine knees. The 3-D OCT imaging of articular cartilage enables the assembly of 126 individual, adjacent, rapid scanned OCT images into a full 3-D image representation of the tissue scanned, or these may be viewed in a progression of successive individual two-dimensional (2-D) OCT images arranged in 3-D orientation. A fiber-based frequency domain OCT system that provides cross-sectional images was used to acquire 126 successive adjacent images for a sample volume of $6{\times}3.2{\times}2.5\;mm^3$. The axial resolution was $8\;{\mu}m$ in air. The 3-D OCT was able to demonstrate surface topography and subsurface disruption of articular cartilage consistent with the gross image as well as with histological cross-sections of the specimen. The 3-D OCT volumetric imaging of articular cartilage provides an enhanced appreciation and better understanding of regional degenerative joint disease than may be realized by individual 2-D OCT sectional images.