T 세포활성항원 CTLA-4의 기능에 관한 연구 : T 세포에서 표적세포 살해능과 CTLA-4 발현과의 연관성 Target Cytotoxicity of T Cell Correlates with CTLA-4 Production

노만택,조양자,김용식,최용,조보현,최장원,정용훈 大韓免疫學會 1996 大韓免疫學會誌 Vol.18 No.4

CTLA-4, a T cell activation antigen and a homologue of CD28, was originally identified as a gene by a series of reverse genetic approaches. While CD28 molecule has been characterized well as a stimulator of T-cell function via enhanced lymphokines production and stablilization of those mRNA, most of the functions of CTLA-4 remain unknown. It has been widely accepted that CTLA-4 functions as an immune suppressor which is down-regualting the function of CD28. We previously showed that 34 KD form of this antigen mainly expressed CD8+ subset, a cytotoxic or suppressor, of activated peripheral blood lymphocyte. Based on our previous finding this study was conducted to further characterize immunological function of CTLA-4 especially in terms of involvement of this molecule in T-cell effector function mediating target cell cytotoxicity. 4 human T cell clones with different target cytotoxicities were employed in this study. NBL46 (CD4+) and NBL77 (CD8+) were cytotoxic and NBL32 (CD4+) and NBL58 (CD 8+) were non-cytotoxic to target LBF cell in target cell chromium release assay. And in Western blot assay 34 kD antigen was detected in NBL46 (CD4+) and NBL77 (CD8+) clones but not in NBL32 (CD4+) and NBL58 (CD8+) clones. It was summarized that expression of the CTLA-4 antigen was associated with cytotoxicity but not with subset phenotypes of T cells. In conclusion CD8+ T subset of PHA-stimulated PBL was major and only CTLA-4 producer and this molecule was induced during mid to late stage of T cell activation. The cytotoxicity of T cell clones to its target cell was directly correlated with its CTLA-4 production and vice versa. And it was highly suggested that primary function of CTLA-4 may involved in T cell effector function which mediates target cell killing.

MPEG-7 Homogeneous Texture Descriptor

Ro, Yong-Man,Kim, Mun-Churl,Kang, Ho-Kyung,Manjunath, B.S.,Kim, Jin-Woong Electronics and Telecommunications Research Instit 2001 ETRI Journal Vol.23 No.2

MPEG-7 standardization work has started with the aims of providing fundamental tools for describing multimedia contents. MPEG-7 defines the syntax and semantics of descriptors and description schemes so that they may be used as fundamental tools for multimedia content description. In this paper, we introduce a texture based image description and retrieval method, which is adopted as the homogeneous texture descriptor in the visual part of the MPEG-7 final committee draft. The current MPEG-7 homogeneous texture descriptor consists of the mean, the standard deviation value of an image, energy, and energy deviation values of Fourier transform of the image. These are extracted from partitioned frequency channels based on the human visual system (HVS). For reliable extraction of the texture descriptor, Radon transformation is employed. This is suitable for HVS behavior. We also introduce various matching methods; for example, intensity-invariant, rotation-invariant and/or scale-invariant matching. This technique retrieves relevant texture images when the user gives a querying texture image. In order to show the promising performance of the texture descriptor, we take the experimental results with the MPEG-7 test sets. Experimental results show that the MPEG-7 texture descriptor gives an efficient and effective retrieval rate. Furthermore, it gives fast feature extraction time for constructing the texture descriptor.

Progressive Reconstruction Technique Using Matching Pursuit in MRI

Ro, Yong-Man,Avideh Zakhor 大田大學校 産業技術硏究所 1997 산업기술연구소 論文集 Vol.8 No.1

A progressive reconstruction technique is presented in magnetic resonance (MR) imaging. Matching pursuit (MP) algorithm developed by Mallat is modified and applied to MR Imaging. For MR imaging, Fourier basis set is used as a dictionary of MP algorithm. In the progressive reconstruction algorithm proposed in this paper, the inner products of object signal and basis functions are utilized instead of those of residual signals and basis functions for original matching pursuit algorithm. By reconstructing the object hierarchically, one can achieve a quick recognition of image during data acquisition, i.e., at each phase encoding step, the image is reconstructed and updated progressively while, in conventional, image reconstruction is performed after all phase encoding steps. To verify the proposed technique, computer simulations and experiments with 2.0 T NMR machine are performed.

동심 방사 표본방식을 이용한 자기공명 영상의 흐름운동 감소

노용만 大田大學校 産業技術硏究所 1994 산업기술연구소 論文集 Vol.1994 No.7

자기공명 영상법에서 기존의 방법인 KWE 방법으로 지퍼와 같은 모양으로 영상을 왜곡시킨다. 반면에 선적분 투영 재구성법(LPR)은 흐름의 운동을 감소시키거나 T₂가 짧은 물체를 영상화 할 수 있는 장점을 가지고 있다. 그러나 LPR 방법은 필터링과 재투영과정을 거쳐야 하므로 영상의 구성 시간이 많이 걸린다는 단점이 있다. 이런 긴 LPR의 영상 구성시간을 단축시키기 위하여 동심 방사 표본 방식(CRSC)이 제안되었으며 영상 구성시간의 단축을 위한 CSRC 알고리즘을 구현하였다. 본 논문에서는 CSRC를 이용하여 흐름운동을 감소시키는 영상법을 구현하였다. 컴퓨터 모의 실험과 2.0 T NMR시스템을 이용한 실험을 통해서 제안된 알고리즘의 위상변화와 흐름운동에 의한 효화를 감소하며 영상 재구성 시간이 단축됨을 보였다. In the conventional KWE method in MRI(Magnetic Resonance Imaging), pulsatile nature of blood flow makes zipper-like artifact along the direction of phase encoding, On the other hand, line-intergral projection reconstruction (LPR)method has advantages such as imaging of short T₂object and elimination of the phase fluctuation due to flow. The LPR, however, necessarily requires filtering and back-projection processes, so that the reconstruction takes a lot of time. To overcome the long reconstruction time of LPR, a concentric square rater sampling scheme(CSRS) method was developed. A fast reconstruction scheme (CSRS) method was developed. The CSRS is a fast reconstruction method that has same properties as LPR. In this paper, a new method of flow artifact reduction using CSRS is proposed, Through computer simulations and experiments, it was verified that the proposed technique can eliminate phase fluctuations, reduce flow artifact. and shorten the reconstruction time. All experiment were performed with 2.0 T NMR system.

Visual Importance- and Discomfort Region-Selective Low-Pass Filtering for Reducing Visual Discomfort in Stereoscopic Displays

Yong Ju Jung,Hosik Sohn,Seong-il Lee,Speranza, Filippo,Yong Man Ro IEEE 2013 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDE Vol.23 No.8

<P>In human vision, the depth of focus (DOF) blur is important to perceive single binocular vision. Unfortunately, conventional stereoscopic displays cannot provide a natural DOF blur effect. Synthetic DOF blur that simulates the natural DOF blur effect could be useful for reducing the visual discomfort in stereoscopic displays. However, the incorrect introduction of artificial blur in the image might also have negative effects. This paper proposes a selective DOF blur technique that is applied only to local regions that induce high visual discomfort but are less visually important. We employ a visual importance analysis to obtain reasonable estimates of the areas/objects that are likely to be attended using saliency maps. After identifying the regions likely to cause discomfort because of excessive relative disparity, we apply low-pass filtering for the less-salient neighboring pixels of the discomfort regions. We demonstrate that the DOF blur simulation for less important background regions that induce visual discomfort is helpful in reducing the visual discomfort in stereoscopic viewing.</P>

Towards a Physiology-Based Measure of Visual Discomfort: Brain Activity Measurement While Viewing Stereoscopic Images With Different Screen Disparities

Yong Ju Jung,Dongchan Kim,Hosik Sohn,Seong-il Lee,Hyun Wook Park,Yong Man Ro IEEE 2015 Journal of display technology Vol.11 No.9

<P>In this study, we tried to identify the cortical areas associated with the experience of visual discomfort in the viewing of stereoscopic images. To this purpose, we first conducted a subjective assessment experiment to select, based on viewers' opinions, two sets of stereoscopic video sequences: one comprising video sequences generally rated as comfortable and the other comprising video sequences generally rated as uncomfortable. The two sets differed mainly with respect to the absence or presence of excessive screen disparities. Next, we used these video sequences as stimuli in two functional magnetic resonance imaging (fMRI) experiments so that we could identify differences, if any, in brain activation while viewing comfortable and uncomfortable video sequences. We found that, compared to comfortable videos with small screen disparities, uncomfortable videos with excessive screen disparities resulted in significantly higher levels of activation in the following brain areas: the right middle frontal gyrus (MFG), the right inferior frontal gyrus (IFG), the right inferior parietal lobule (IPL), the right middle temporal gyrus (MTG), the bilateral lingual gyri, the bilateral cuneus, and the right precuneus. The results of the fMRI experiments suggest that visual discomfort due to excessive screen disparities can be caused by sensory (related with the subjective sensation of fusion difficulty and vision clarity) and/or motor (related with unnatural eye movements) phenomena. The intraparietal sulcus (IPS) regions in the human brain may be involved in the sensory phenomenon, and the frontal eye field (FEF), premotor cortex, and IPS regions may be involved in the motor phenomenon.</P>

Predicting Visual Discomfort of Stereoscopic Images Using Human Attention Model

Yong Ju Jung,Hosik Sohn,Seong-Il Lee,Hyun Wook Park,Yong Man Ro IEEE 2013 IEEE transactions on circuits and systems for vide Vol.23 No.12

<P>We introduce a new objective assessment method for visual discomfort of stereoscopic images that makes effective use of the human visual attention model. The proposed method takes into account visual importance regions that play an important role in determining the overall degree of visual discomfort of a stereoscopic image. After obtaining a saliency-based visual importance map for an image, perceptually significant disparity features are extracted to predict the overall degree of visual discomfort. Experimental results show that the proposed method can achieve significantly higher prediction accuracy than the state-of-the-art methods.</P>

Visual discomfort visualizer using stereo vision and time-of-flight depth cameras

Yong Ju Jung,Hosik Sohn,Yong Man Ro IEEE 2012 IEEE transactions on consumer electronics Vol.58 No.2

<P>Visual discomfort monitoring is an important technique for comfortable viewing of stereoscopic images. This paper proposes a novel monitoring system of visual discomfort that takes advantages of a fusion camera system equipped with stereo vision cameras and a time-of-flight camera. We improve disparity map enhancement technique to obtain a high-quality disparity map that is aligned to the right view color image coordinate. The captured stereo-plusdisparity images are used for visual discomfort visualizer that automatically predicts overall degree of perceived visual discomfort and visualizes which regions are problematic in terms of visual discomfort. The proposed visual discomfort visualizer is based on visual importance of image scenes, resulting in considerable improvement in prediction performance of visual discomfort. The experimental results showed that the proposed system could generate enhanced disparity maps and achieve visual discomfort prediction accuracy that is feasible for practical applications.</P>

자기공명 영상에서의 자화율 효과에 관한 신호처리

노용만 大田大學校 産業技術硏究所 1992 산업기술연구소 論文集 Vol.3 No.2

핵자기공명 영상법에서의 자화율에 의한 효과를 조절할 수 있는 새로운 신호처리방법을 제안하였다. 이 방법을 자화율로 인한 국부적으로 불균형하게 되는 자계의 경우에 적용하였다. 본 논문에서는 이런 자화율에 의해서 영상내의 신호가 감소되거나 없어지는 현상을 수식적으로 나타냈으며 이를 바탕으로 새로운 신호처리법을 소개했다. 이 방법의 한 응용으로 자화율효과만을 이용한 혈관영상법을 제안하였다. 일반적으로 혈액의 deoxyhemoglobin 성분은 강자성체의 특성을 띄며 자기공명영상에서 자화율에 의해 영향을 받는다. 새로운 혈관영상법은 이런 자화율 효과가 있는 부분은 신호를 살리고 다른 부분은 신호를 없애서 혈관만의 영상이 가능하도록 하였다. 마지막으로 컴퓨터 모의 결과와 2.0 Tesla의 NMR장치를 이용한 실험결과를 통해 이방법의 유용성을 보였다.

Content Adaptation based on Metadata Hiding

Yong Ju Jung(정용주),Ho Kyung Kang(강호경),Yong Man Ro(노용만) 대한전자공학회 2003 대한전자공학회 학술대회 Vol.2003 No.11