• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.492-496
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• 2001

Due to their better photosensitivity in X-ray, the amorphous selenium based photoreceptor is widely used on the X-ray conversion materials. It was possible to control the charge carrier transport of amorphous selenium by suitably alloying a-Se with other elements(e,g. As, Cl). In this paper, We investigated dopants(As, Cl) composition rate to improve dark resistivity and transport properties of charge carrier in amorphous selenium using by direct X-ray conversion material. Alloying a-Se with As inhibits the recrystallization of a-Se but introduces undesirable deep hole traps. then doping with Cl(in the ppm range) compensates for the deep hole traps. We investigated their composition rate in various doping conditions and then obtained optimum dopant composition rate. The result was Se-As 0.3%-c] 30 ppm and X-ray Sensitivity was 0.57 pC/$pixel{\cdot}mR$ at $137{\mu}m{\times}137{\mu}m$ Pixel area.

• Plant Biotechnology Reports
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• 제2권1호
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• pp.59-73
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• 2008

Several aspects of photoperception and light signal transduction have been elucidated by studies with model plants. However, the information available for economically important crops, such as Fabaceae species, is scarce. In order to incorporate the existing genomic tools into a strategy to advance soybean research, we have investigated publicly available expressed sequence tag (EST) sequence databases in order to identify Glycine max sequences related to genes involved in light-regulated developmental control in model plants. Approximately 38,000 sequences from open-access databases were investigated, and all bona fide and putative photoreceptor gene families were found in soybean sequence databases. We have identified G. max orthologs for several families of transcriptional regulators and cytoplasmic proteins mediating photoreceptor-induced responses, although some important Arabidopsis phytochrome-signaling components are absent. Moreover, soybean and Arabidopsis genefamily homologs appear to have undergone a distinct expansion process in some cases. We propose a working model of light perception, signal transduction and response-eliciting in G. max, based on the identified key components from Arabidopsis. These results demonstrate the power of comparative genomics between model systems and crop species to elucidate several aspects of plant physiology and metabolism.

• Applied Microscopy
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• 제37권1호
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• pp.35-42
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• 2007

감간분체 (Rhabdomere)가 왕성하게 형성되는 번데기시기의 Drosophila melanogaster 광수용체 세포를 고정효과가 가장 좋은 high-pressure freezing (HPF)와 freeze-substitution (FS) 기법으로 고정한 후, 초고압 전자현미경을 통하여 1000 KV 전압에서 관찰하였다. 후박절편(250nm)의 tilting image를 통하여 광수용체 세포에서 감간분체 형성의 세가지 형태가 관찰되었다. 첫째로, 감간분체의 육방정계 배열이 (hexagonal may) 서로 다른 각도로 존재하고 있음을 관찰할 수 있었다. 둘째, 광수용체 세포의 세포질 안에서 감간분체 형성의 중간 과정으로 보여지는 작은 조각의 감간분체를 관찰할 수 있었다. 셋째, 감각분체가 여러 개의 층으로 형성되어 있음을 관찰할 수 있었다. 또 광수용체 세포의 세포질에는 최소한 세 가지의 소낭(vesicle)이 존재하였고, 이들 소낭들은 번데기 시기의 감각분체 형성을 주도하는 것으로 확인되었다. 이 결과들에 의하여 소낭이 감각분체 형성과 감각분체의 부분들이 모여서 감각분체를 완성되는 과정에 관여함을 추정할 수 있었다.

• 생명과학회지
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• 제29권3호
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• pp.311-317
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• 2019

빛의 파장이 넙치의 성장에 미치는 영향을 분석하기 위하여 보라색(400 nm), 청색(465 nm), 녹색(508 nm), 그리고 적색(635 nm)의 LED와 백색 형광등하에서 성장 실험을 수행하였다. 수조당 15마리 넙치를 12:12 시간 각 파장 LED의 광주기하에서 60일 동안 사육한 결과, 각기 $269.92{\pm}13.02%$와 $2.18{\pm}0.06$(보라색), $363.21{\pm}3.74%$와 $2.56{\pm}0.07$(청색), $433.22{\pm}4.83%$와 $2.79{\pm}0.01$(녹색), $290.17{\pm}11.83$와 $2.27{\pm}0.05$(적색), 그리고 $340.74{\pm}26.58%$와 $2.47{\pm}0.10$(형광등)의 체중 증가와 일간성장률(SGR: %/day)이 관찰되었다. 본 실험 결과 녹색 LED 하에서 넙치의 성장이 가장 빨랐으며, 적색 조명 하에서는 성장이 느린 것으로 나타났다. 대부분의 혈액 지표는 그룹별 차이가 없으나, 적색 LED조명 하에서 자란 넙치에서 높은 수준의 glutamic oxaloacetic transaminase (GOT)가 관찰되었다. 빛의 1차 감지 기관인 망막의 조직학적 분석 결과 광수용체 층의 상대적 두께에 별다른 영향이 없는 것으로 보아 녹색광이 무해함을 유추할 수 있다.

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2008년도 제49회 학술심포지움 및 국제학술대회
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• pp.52.1-52.1
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• 2008

• Biomolecules & Therapeutics
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• 제22권6호
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• pp.491-496
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• 2014

Photobiomodulation utilizes monochromatic (or quasimonochromatic) light in the electromagnetic region of 600~1000 nm for the treatment of soft tissues in a nondestructive and nonthermal mode. It is conceivable that photobiomodulation is based upon the ability of the light to alter cell metabolism as it is absorbed by general hemoproteins and cytochrome c oxidase (COX) in particular. Recently it has been suggested radiation of visible and infrared (IR) activates retrograde signaling pathway from mitochondria to nucleus. In this review, the role of COX in the photobiomodulation will be discussed. Further a possible role of water as a photoreceptor will be suggested.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2000년도 하계종합학술대회논문집
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• pp.201-204
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• 2000

본 논문에서는 기존의 칼라 항상성(color constancy) 알고리즘을 기반으로 한 새로운 영상 복원 방법을 제안한다. 이 방법은 인간의 시각 특성을 선형 모델로 표현한 칼라 항상성 모델을 이용한다. 칼라 항상성 모델에서 가장 중요한 과정은 영상의 광원을 추정하는 것이다. 이론 위하여 영상에서 명도 값이 가장 큰 화소의 값을 이용하며, 이 값을 각 수광체(photoreceptor)의 응답으로 대체한다. 추정된 광원을 이용하여 만들어진 영상을 일정한 비율로 스케일링하여 영상을 복원한다. 실험을 통하여 제안한 항법으로 영상 복원이 잘 됨을 알 수 있었다.

• Journal of Photoscience
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• 제9권2호
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• pp.98-101
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• 2002

Euglena gracilis abruptly changes its swimming direction after a sudden increase or decrease in incident light intensity, that is, step-up or step-down photophobic responses, resulting in photoavoidance or photoaccumulation, respectively. To identify the photoreceptor molecules for these UV-A/blue-light type photobehaviors, we purified a flavoprotein from isolated putative photosencory organelles (PFBs) of Euglena. The purified flavoprotein, which noncovalently bound flavin adenine dinucleotide (FAD), seemed to be a heterotetramer of alpha- and beta-subunits. Predicted amino acid sequences of each of the subunits were similar to each other and contained two FAD-binding domains each followed by an adenylyl cyclase catalytic domain. The purified flavoprotein actually showed adenylyl cyclase activity, being drastically elevated by blue-light irradiation. Suppression of gene expression of the flavoprotein (Photoactivated Adenylyl Cyclase, PAC) by RNA interference (RNAi) caused loss of the step-up photophobic response, demonstrating that PAC actually mediates photoavoidance of Euglena.

• Plant Biotechnology Reports
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• 제4권2호
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• pp.149-155
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• 2010

Expression of the genes for carotenoid bio-synthesis (crt) is dependent on light, but little is known about the underlying mechanism of light sensing and signalling in the cyanobacterium Synechocystis sp. PCC 6803 (hereafter, Synechocystis). In the present study, we investigated the light-induced increase in the transcript levels of Synechocystis crt genes, including phytoene synthase (crtB), phytoene desaturase (crtP), ${\zeta}$-carotene desaturase (crtQ), and ${\beta}$-carotene hydroxylase (crtR), during a darkto-light transition period. During the dark-to-light shift, the increase in the crt transcript levels was not affected by mutations in cyanobacterial photoreceptors, such as phytochromes (cph1, cph2 and cph3) and a cryptochrome-type photoreceptor (ccry), or respiratory electron transport components NDH and Cyd/CtaI. However, treatment with photosynthetic electron transport inhibitors significantly diminished the accumulation of crt gene transcripts. Therefore, the light induction of the Synechocystis crt gene expression is most likely mediated by photosynthetic electron transport rather than by cyanobacterial photoreceptors during the dark-to-light transition.

• 대한의용생체공학회:의공학회지
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• 제30권4호
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• pp.347-354
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• 2009

For the reliable transmission of meaningful visual information using prosthetic electrical stimulation, it is required to develop an effective stimulation strategy for the generation of electrical pulse trains based on input visual information. The characteristics of neuronal activities of retinal ganglion cells (RGCs) evoked by electrical stimulation should be understood for this purpose. In this study, for the development of an optimal stimulation strategy for visual prosthesis, we analyzed the neuronal responses of RGCs in rd1 mouse, photoreceptor-degenerated retina of animal model of retinal diseases (retinitis pigmentosa). Based on the in-vitro model of epiretinal prosthesis which consists of planar multielectrode array (MEA) and retinal patch, we recorded and analyzed multiunit RGC activities evoked by amplitude-modulated electrical pulse trains. Two modes of responses were observed. Short-latency responses occurring at 3 ms after the stimulation were estimated to be from direct stimulation of RGCs. Long-latency responses were also observed mainly at 2 - 100 ms after stimulation and showed rhythmic firing with same frequency as the oscillatory background field potential. The long-latency responses could be modulated by pulse amplitude and duration. From the results, we expect that optimal stimulation conditions such as pulse amplitude and pulse duration can be determined for the successful transmission of visual information by electrical stimulation.