• International Journal of Contents
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• 제2권3호
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• pp.27-32
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• 2006

We present an effective algorithm for automatic tracing of retinal vessel structure and vascular landmark extraction of bifurcations and ending points. In this paper we deal with vascular patterns from RGB images for personal identification. Vessel tracing algorithms are of interest in a variety of biometric and medical application such as personal identification, biometrics, and ophthalmic disorders like vessel change detection. However eye surface vasculature tracing in RGB images has many problems which are subject to improper illumination, glare, fade-out, shadow and artifacts arising from reflection, refraction, and dispersion. The proposed algorithm on vascular tracing employs multi-stage processing of ten-layers as followings: Image Acquisition, Image Enhancement by gray scale retinal image enhancement, reducing background artifact and illuminations and removing interlacing minute characteristics of vessels, Vascular Structure Extraction by connecting broken vessels, extracting vascular structure using eight directional information, and extracting retinal vascular structure, and Vascular Landmark Extraction by extracting bifurcations and ending points. The results of automatic retinal vessel extraction using jive different thresholds applied 34 eye images are presented. The results of vasculature tracing algorithm shows that the suggested algorithm can obtain not only robust and accurate vessel tracing but also vascular landmarks according to thresholds.

• Applied Microscopy
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• 제37권3호
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• pp.175-183
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• 2007

정확한 세포의 구조 분석을 위해서는 조직을 가능한 한 자연 상태 그대로 보존하는 것이 무엇보다 중요하다. 그러나 지금까지 이용되고 있는 화학적인 고정방법은 조직의 변형을 유도하는 것으로 알려져 그 해결방법에 관한 연구가 활발히 진행되고 있다. 그 연구의 결과로 현재 급속 동결법이 제시되었고, 그 중 초고압동결법(high-pressure freezing method)는 가용 두께가 $200{\mu}m$로서 $10{\sim}15{\mu}m$정도인 침윤동결법(plunging method) 혹은 접촉동결법 (slamming method)보다 우수한 방법으로 보고되고 있다. 본 연구팀에는 노랑초파리(Drosophila melanogaster)의 레티나를 화학고정법과 고압동결법으로 고정하여 미세구조를 비교하였다. 먼저 120kV 전자현미경을 이용하여 각 세포 소기관을 비교하였고, 그 중 미토콘드리아의 형태변화를 좀 더 자세히 비교하기 위하여 초고압전자현미경을 이용하였다. 그 결과 급속동결 세포의 세포막과 미토콘드리아의 고정에서 특히 차이가 있음을 알 수 있었고, 이는 주로 탈수에 의한 구조변형 때문인 것으로 추측된다.

• Journal of Dental Anesthesia and Pain Medicine
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• 제19권1호
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• pp.37-44
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• 2019

Objective: Arthrocentesis is a minimally invasive surgical procedure that is used to alleviate the symptoms of temporomandibular joint (TMJ) disorders. The aim of this study was to investigate the effect of arthrocentesis on the blood supply to the retinal structures. Materials and Methods: Arthrocentesis was performed on 20 patients with TMJ disorders, and choroidal thickness (CT) in patients was measured to evaluate retinal blood circulation. The blood volume of the retinal structures was evaluated ipsilaterally before and after arthrocentesis, and these measurements were then compared with measurements obtained from the contralateral side. Results: Before arthrocentesis, there were no differences in retinal blood volumes between the ipsilateral and contralateral sides (P = 0.96). When ipsilateral CT measurements taken before and after arthrocentesis were compared, retinal blood supply was found to have significantly decreased after arthrocentesis (P = 0.04). When contralateral CT measurements taken before and after arthrocentesis were compared, retinal blood supply was also found to have decreased after arthrocentesis, but not significantly (P = 0.19). Conclusion: The solution of local anesthesia with epinephrine applied before the arthrocentesis procedure was found to reduce the blood volume of the retinal structures. To the best of our knowledge, this is the first study that has investigated the blood volume of the retinal structures following arthrocentesis.

• 한국임상수의학회지
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• 제14권2호
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• pp.235-237
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• 1997

Cataract and Retinal detachment eyes dogs were examined by ultrasonography. Ultrasonography of the immature and mature cataractous eyes showed echographic changes, and cataractous lens increased in thickness. The diagnosis of retinal detachment was made an echodense waving motion structure in the posterior segment was imaged. This investigation will provide basic information for the study of pathologic conditions affecting the eyes of dog using ultrasound unit commonly available to the veterinarian.

• ETRI Journal
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• 제29권1호
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• pp.59-69
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• 2007

We designed and fabricated a vision chip for edge detection with a $160{\times}120$ pixel array by using 0.35 ${\mu}m$ standard complementary metal-oxide-semiconductor (CMOS) technology. The designed vision chip is based on a retinal structure with a resistive network to improve the speed of operation. To improve the quality of final edge images, we applied a saturating resistive circuit to the resistive network. The light-adaptation mechanism of the edge detection circuit was quantitatively analyzed using a simple model of the saturating resistive element. To verify improvement, we compared the simulation results of the proposed circuit to the results of previous circuits.

• 한국안광학회지
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• 제1권1호
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• pp.15-22
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• 1996

본 연구는 망막조직의 미세구조를 전자현미경을 이용하여, 생쥐(ICR)에 대한 Laser 조사의 영향을 조사하였다. 그 결과는 다음과 같다. l. 정상군에서 대개의 망막층은 여러 특수한 세포들과 신경섬유로 구성된 복잡한 구조를 가지고 있었다. 2. Laser 조사의 기간이 길어질수록, 망막의 각 세포의 층과 구조는 일정한 형태를 나타내지 못했다. 시세포 visual cell들은 심하게 이형염색질체 heterochromatin이며, 세포질은 종대되며, 핵의 모양은 불규칙적이며,일부의 세포질은 소실되었다. 망막층의 핵과 신경섬유는 매우 불규칙적이며, 소포의 형성, 각 세포간 경계의 불명확함이 있었다. 색소상피세포 pigment epithelail cell들은 정상모양이 아니며, 세포질에는 큰 공포 형성이 있으며, 핵의 응축과 불규칙한 모양 등이 있었다.

• 한국정보과학회논문지:소프트웨어및응용
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• 제29권3호
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• pp.202-210
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• 2002

최근 수년 동안 의료영상에서 혈관의 추출 및 재구성에 관한 연구가 활발히 진행되어 오고 있으며 망막혈관 구조의 분석은 망막에 관련된 환자의 진단 및 치료에 중요한 정보를 제공하여 왔다. 본 연구에서는 ICG(Indocyanine Green) 기술에 의해 촬영된 망막영상에서 전체 망막혈관을 자동으로 추적하는 알고리즘을 제안한다 본 알고리즘은 각 혈관의 기울기크기 단면도(profile)로부터 국부적 최대점들(local maxima)과 처리방향을 평가하여 혈관의 외형과 중심을 추출하며, 국부적 최대점들의 방향성분을 비교하여 혈관의 분기점 및 교차점을 감지한다. 본 알고리즘을 환자의 ICG 망막영상에 적용하여 전체혈관이 자동으로 재구성되었으며 정확성과 연결성이 우수하다는 점을 실험결과로 제시하였다.

• Advances in nano research
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• 제13권1호
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• pp.87-96
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• 2022

Drug self-delivery systems can easily realize combination drug therapy and avoid carrier-induced toxicity and immunogenicity because they do not need non-therapeutic carrier materials. So, designing appropriate drug self-delivery systems for specific diseases can settle most of the problems existing in traditional drug delivery systems. Retinal pigment epithelium is very important for the homeostasis of retina. However, it is vulnerable to oxidative damage and difficult to repair. Worse still, the antioxidants can hardly reach the retina by non-invasive administration routes due to the ocular barriers. Herein, the targeted group (folic acid) and antioxidant (melatonin) have been grafted on the surface of ZnO quantum dots to fabricate a new kind of drug self-delivery systems as a protectant via eyedrops. In this study, the negative nanoparticles with size ranging in 4~6 nm were successfully synthesized. They could easily and precisely deliver drugs to retinal pigment epithelium via eyedrops. And they realized acid degradation to controlled release of melatonin and zinc in retinal pigment epithelium cells. Consequently, the structure of retinal pigment epithelium cells were stabilized according to the expression of ZO-1 and β-catenin. Moreover, the antioxidant capacity of retinal pigment epithelium were enhanced both in health mice and photic injury mice. Therefore, such new drug self-delivery systems have great potential both in prevention and treatment of oxidative damage induced retinal diseases.

• Journal of Photoscience
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• 제2권1호
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• pp.19-25
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• 1995

Picosecond time-resolved and static protein fluorescence spectra and absorption spectra of octopus rhodopsin, a photorecepting protein, are measured and compared with those of bacteriorhodopsin, a photon-induced proton pumping protein, to understand the protein conformations and functions of octopus rhodopsin and its deprotonated photocycle intermediate. The bluer and weaker absorption of retinal indicates that octopus rhodopsin is better in thermal noise suppression but less efficient in light harvesting than bacteriorhodopsin. The protein fluorescence of octopus rhodopsin shows the characteristic of Trp only and the uantum efficiency and lifetime variations may result primarily from variations in the coupling strength with the retinal. The stronger intensity by four times and larger red shift by 12 nm of fluorescence suggest that octopus rhodopsin has more open and looser structure compared with bacteriorhodopsin. Fluorescence decay profiles reveal two decay components of 300 ps (60%) and 2 ns (40%). The deprotonation of protonated Schiff's base increases the shorter decay time to 500 ps and enhances the fluorescence intensity by 20%. The fluorescence and its decay time from Trp residues near retinal are influenced more by the deprotonation. The increase of fluorescence intimates that protein structure becomes loosened and relaxed further by the deprotonation of protonated Schiff's base. The driving force of sequential changes initiated by absorption of a photon is too exhausted after the deprotonation to return the intermediate to the ground state of the begun rhodopsin form.

• 한국어류학회지
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• 제20권2호
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• pp.97-104
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• 2008

한국산 고유 담수 어종인 참갈겨니와 눈동자개의 안구 외부형태와 망막구조를 광학현미경과 전자현미경으로 비교 조사하였다. 참갈겨니는 안구의 크기뿐만 아니라 수평안경/체장, 수평안경/두장의 비율이 모두 눈동자개보다 크게 나타났고 다만, 수정체직경/수평안경은 눈동자개가 더 크게 나타났다. 망막의 시각세포층에서 참갈겨니는 크게 단일원뿔세포와 이중원뿔세포, 두 종류의 원뿔세포를 가지며 단일원뿔세포는 긴단일원뿔세포와 짧은단일원뿔세포로 나뉜다. 반면 눈동자개는 긴단일원뿔세포와 짧은단일원뿔세포로 구분할 수 없는 단지 단일원뿔세포로만 구성되어 있었다. 또한 원뿔세포의 배열구조에 있어서도 참갈겨니는 보다 치밀한 열구조로 배열되어 있는 반면 눈동자개는 성긴 불규칙한 구조로 배열되어 있었다. 이상과 같이 참갈겨니와 눈동자개의 안구 및 망막의 구조적 차이는 2종 간의 생태학적 특성과 밀접한 관련이 있는 것으로 생각된다.