• Science of Emotion and Sensibility
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• v.23 no.3
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• pp.47-62
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• 2020

The snake detection theory posits that, due to competition with snakes, the primate visual system has been evolved to detect camouflaged snakes. Specifically, one of its hypotheses states that the subcortical visual pathway mainly consisting of koniocellular cells enables humans to automatically detect the threat of snakes without consuming mental resources. Here we tested the hypothesis by comparing human participants' responses to snakes with those to fearful faces and flowers. Participants viewed either original images or converted ones, which lacked the differences in color, luminance, contrast, and spatial frequency energies between categories. While participants in Experiment 1 produced valence and arousal ratings to each image, those in Experiment 2 detected target images in the breaking continuous flash suppression (bCFS) paradigm. As a result, visual factors influenced the responses to snakes most strongly. After minimizing visual differences, snakes were rated as being less negative and less arousing, and detected more slowly from suppression. In contrast, the images of the other categories were less affected by image conversion. In particular, fearful faces were rated as greater threats and detected more quickly than other categories. In addition, for snakes, changes in arousal ratings and those in bCFS response times were negatively correlated: Those snake images, the arousal ratings of which decreased, produced increased detection latency. These findings suggest that the influence of snakes on human responses to threat is limited relative to fearful faces, and that detection responses in bCFS share common processing mechanisms with conscious ratings. In conclusion, the current study calls into question the assumption that snake detection in humans is a product of unconscious subcortical visual processing.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.3
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• pp.151-158
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• 2007

In this study we investigated the embryo toxicity of three kinds of plant extracts during early development of African clawed frog, Xenopus laevis through FETAX assay (Frog Embryo Teratogenesis Aassay with Xenopus). The plants used in this study were the materials of the Korean herbal medicines, Polygala tenuifolia, Lycium chinensis and Comus officinalis. The test embryos exposed to 1, 10 and $100{\mu}g/ml$ of each plant extract and control embryos were incubated for 96h at $24{\pm}0.5^{\circ}C$. The focus of this study is to elucidate the malformation due to toxicity of plant extracts, especially, to elucidate plant inducing optic malformation. As a result, the growth inhibition of embryos, optic malformation, axial distortion, cephalic and abdominal edema, dysplasia of digestive track and hyper-pigmentation were occurred in all of extracts, and these malformations were increased to the increase of extract concentration. The rate of optic malformation was highest in $100{\mu}g/ml$ of Lycium chinensistreated group and 27% of tested 150 individuals showed optic hernia. The histological results showed enlarged ventriculum in brain, dysplasia of vitreous chamber in eye and unclear retinal layers.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.2
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• pp.187-191
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• 2013

Purpose: This study was done to understand the visual system of bat by analyzing the distribution of middle/long (ML) opsin cone photoreceptors in the retina of the greater horseshoe bat. Methods: Experiments have been performed by standard immunocytochemical techniques on retina of the greater horseshoe bat Rhinolophus ferrumequinum. Results: The estimated numbers of ML cones were $27,336{\pm}2,130$ cells and the mean density of them was $7,854{\pm}268cells/mm^2$ among the four retinas. S opsin was appeared a little immunoreactivity in the outer segments of outer nuclear layer of cones. Conclusions: From the well organized spatial distributions of ML opsin and the immunoreactivity of S opsin in the retinas, the greater horseshoe bats have the functions not only reacting in the photopic vision but being able to distinguish the colors.

• Development and Reproduction
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• v.16 no.2
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• pp.101-106
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• 2012

Importance of behavior factors or environmental factors in visual organization and visual function of fish is treated with great care in visual ecology, and there is no study about initial ocular growth and development on the dark banded rockfish, Sebastes inermis. Thus, this study was performed. The total length, head length, head depth, eye diameter and lens diameter of the dark banded rockfish showed positive allometric relationship between parturition stage and 60 days post-parturition (dpp). The increase in total length relative to head length and head depth, head length growth relative to eye diameter and lens diameter, and head depth growth relative to eye and lens diameter were nearly isometric. The eyes were formed completely at parturtion stage. At this age, the eye has an optic nerve fiber layer, a ganglion cell layer, an inner plexiform layer, an inner nuclear layer, an outer plexiform layer, an outer nuclear layer, an outer limiting membrane, a rod and cone layer and an epithelial layer. Thickness of retina at 60 dpp was higher than that of at parturition stage. During this experiment, the proportion of the rod and cone layer, outer nuclear layer, and optic nerve fiber layer of retina were significantly increased, while the proportion of the outer plexiform layer, inner nuclear layer and ganglion cell layer of retina were significantly decreased (P<0.05). The essential demands that must be met by the retina in this species pertain to light sensitivity and spatial resolution.

• Korean Journal of Animal Reproduction
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• v.18 no.3
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• pp.191-197
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• 1994

It is generally known that mutations in any of several genes encoding photoreceptor-specific proteins have resulted in retinitis pigmentosa (RP), a disease characterized by losing photoreceptor function with progressive degeneration of photoreceptor cells and eventually leading to blindness. To study the procure and cure of photoreceptor degeneration, we produced transgenic mice. Transgene consisted of a 12.5kb genomic DNA fragment that contains mutated pig rhodopsin gene (Pro-347-Ser) including both the 5'-franking (4.0 kb) and the 3'-franking (2.9 kb) sequences. This gene was used for the production of transgenic mouse. The mutated rhodopsin DNA was microinjected into male pronuclei of fertilized mouse (C57BL /6]) embryos. We detected transgenic animals harboring mutated rhodopsin gene by PCR and Southern blot analysis. These transgenic mice showed stable transmission of microinjected rhodopsin gene into their offspring. Therefore these animals will provide a novel approach to study the mechanism of the photoreceptor degeneration and be provided as a disease model for the treatment of the blind in human.

• The KIPS Transactions:PartB
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• v.10B no.5
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• pp.491-496
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• 2003

We present a new watermark design tool for digital images and digital videos that are based on human visual system (HVS) characteristics. In this tool, basic mechanisms (inhibitory and excitatory behaviour of cells) of HVS are used to determine image dependent upper bound values on watermark insertion. This allows us to insert maximai allowable transparent watermark, which in turn is extremely hard to attack with common image processing, Motion Picture Experts Group (MPEG) compression. As the number of details (e.g. edges) increases in an image, the HVS decrease its sensitivity to the details. In the same manner, as the number of motion increases in a video signal, the HVS decrease its sensitivity to the motions. We model this decreased sensitivity to the details and motions as an (motion) entropy masking. Entropy masking model can be efficiently used to increase the robustness of image and video watermarks. We have shown that our entropy-masking model provides watermark scheme with increased transparency and henceforth increased robustness.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.104-112
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• 2012

Recently, the HDR imaging technique that mimics human eye is incorporated with LCD/LED display devices to deal with mismatch between the real world scene and the displayed image. However, HDR image has a veiling glare limit as well as a scale of the local contrast problem. In order to overcome these problems, several color correction methods, CSR(center/surround Retinex), MSR (Multi-Scale Retinex), tone-mapping method, iCAM06 and so on, are proposed. However, these methods have a dominated color throughout the entire resulting image after performing color correction. Accordingly, this paper presents a new color correction method using dynamic cone response function. The proposed color correction method consists of tone-mapping and dynamic cone response. The tone-mapping is obtained by using a linear interpolation between chromatic and achromatic. Thereafter, the resulting image is processed through the dynamic cone response function, which estimates the dynamic responses of human visual system as well as deals with mismatch between the real scene image and the rendered image. The experiment results show that the proposed method yields better performance of color correction over the conventional methods.

• Journal of The Korean Association For Science Education
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• v.19 no.1
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• pp.29-40
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• 1999

The purpose of the present study was to test hypothesis that, because it uses tri-dimensional sensory pathway which have been showed a higher rate of neural activities than uni- or bi-dimensional's, lab-activity-based instruction is more effective teaching strategy in learning science than verbal-based instruction. In the present study, manipulative teaching strategy that uses visual, somatosensory and auditory information pathway was regarded as a mode of tri-dimensional sensory inputs. In addition, verbal teaching strategy that uses mainly auditory and a little visual information pathway was used as a mode of bi-dimensional sensory inputs. Fifty-six students who failed to successfully solve two proportional reasoning tasks (i.e., pouring water tasks) were sampled for this research from a junior high school. The subjects were randomly divided into a manipulative or a verbal teaching group, and given manipulative or verbal tutoring on the use of proportional reasoning strategies and a test of proportional reasoning during instruction. The results showed that manipulative group's performance on the test of proportional reasoning during instruction showed significantly higher performance than verbal group's (t=2.45, p<0.02). The present study also discussed some educational implications of the results.

• The Journal of the Korea Contents Association
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• v.18 no.11
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• pp.655-664
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• 2018

Retina transforms the external light into electrical signal that stimulates visual cortex of the brain. Electrical modeling of the retina is useful to understand its structure and action that is a prerequisite to implement the retina as a hardware device. This paper introduces a 2-D electrical network model of vertebrate's retina considering signal pathway of retinal cells and synapses. We implemented a simulator of the retina based on the electrical network model to analyze its operation under various circumstances. Compared to the prior studies, It might contribute designing of artificial retina device in terms of that this study specifically observed input and output reactions of each cell and synapse node under various light intensity on the retina.

• Progress in Medical Physics
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• v.14 no.4
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• pp.211-217
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• 2003

The Principal component analysis (PCA) is a well-known data analysis method that is useful in linear feature extraction and data compression. The PCA is a linear transformation that applies an orthogonal rotation to the original data, so as to maximize the retained variance. PCA is a classical technique for obtaining an optimal overall mapping of linearly dependent patterns of correlation between variables (e.g. neurons). PCA provides, in the mean-squared error sense, an optimal linear mapping of the signals which are spread across a group of variables. These signals are concentrated into the first few components, while the noise, i.e. variance which is uncorrelated across variables, is sequestered in the remaining components. PCA has been used extensively to resolve temporal patterns in neurophysiological recordings. Because the retinal signal is stochastic process, PCA can be used to identify the retinal spikes. With excised rabbit eye, retina was isolated. A piece of retina was attached with the ganglion cell side to the surface of the microelectrode array (MEA). The MEA consisted of glass plate with 60 substrate integrated and insulated golden connection lanes terminating in an 8${\times}$8 array (spacing 200 $\mu$m, electrode diameter 30 $\mu$m) in the center of the plate. The MEA 60 system was used for the recording of retinal ganglion cell activity. The action potentials of each channel were sorted by off­line analysis tool. Spikes were detected with a threshold criterion and sorted according to their principal component composition. The first (PC1) and second principal component values (PC2) were calculated using all the waveforms of the each channel and all n time points in the waveform, where several clusters could be separated clearly in two dimension. We verified that PCA-based waveform detection was effective as an initial approach for spike sorting method.