• Journal of Korean Ophthalmic Optics Society
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• v.7 no.1
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• pp.9-13
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• 2002

It is well known that the maximum amplitude of accommodation decreases with increasing age.(Presbyopia). With single vision lenses presbyopia can be corrected only for one viewing distance. With progressive power lenses presbyopia can be corrected for all viewing distances. But there are some other changes in the visual system with age which can not be corrected by spectacle lenses. Pupillary diameter decreases and the light transmission of the ocular media decreases. Therefore old people need more light, they need better illumination. Cone density in the retina decreases, this is only one example for changes in the sensory system. These changes in the visual system cause changes in visual functions. At the age of 80 visual acuity has decreased to half. Contrast sensitivity for gratings decreases mainly for high spatial frequencies very important is the increase of stray light in the ocular media and therefore the increase of glare. Veiling luminance increases by a multiple of approximately 4, Dark adaptation gets slower and light sensitivity is approximately 2 log units (factor 100) less when the eye is completely dark adapted. Also colour vision gets worse, especially at low luminances. Elderly people have problems with visual tasks which require divided attention between foveal and peripheral vision. An example is the measurement of the useful field of view. This useful field of view be expanded (improved) by visual training.

• Korean Journal of Ichthyology
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• v.11 no.2
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• pp.143-148
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• 1999

Two sibling species of the genus Platycephalus collected from the South and West Sea of Korea were reviewed based on the several meristic and morphological characters, electrophoresis of muscle protein, and LDH and MDH isozyme. Counts and morphometric characters of Platycephalus indicus were different from those of Platycephalus sp. by having 18~20 pectoral fin rays (16~19 in Platycephalus sp.), 70~80 scales of lateral line (83~100), 10.2~13.1% eye diameter (10.9~15.5%), 14.5~18.1% interorbital width (11.8~17.8%), dark brown of body color (light brown) and dark brown of pectoral and ventral fin outside (light brown and pale). The number of soluble protein bands in muscle separated by polyacrylamidegel electrophoresis was 16 and 18 from P. indicus and Platycephalus sp, respectively, and each bands showed their characteristics in activated degree. The number of bands separated from LDH isozyme were 2 and 1 in P. indicus and Platycephalus sp. and in the case of MDH isozyme, 5 and 4 bands, respectively. So we were thought that P. indicus and Platycephalus sp. from Korea were different species each other.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.3
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• pp.37-42
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• 2009

Purpose: There is uncertainty if the vergence facility would provide clinically significant supplementary information to the fusional vergence measurements. The purpose of this study was to determine the relationship between vergence facility and fusional vergence in a group of symptomatic subjects. Methods: A total of 114 symptomatic subjects aged 9 to 13 years, who passed the vision screening test, participated in this study. Vergence facility was measured with 8$\Delta$ BI/8$\Delta$ BO flipper lenses and a suppression control target, the 20/30 letter line on Vectogram 9 (Bernell, USA). Near fusional vergence was measured with a single 20/30 vertical line target by Von Graefe technique. In order to avoid excessive convergence stimulation, negative fusional vergence (NFV) range (blur, break and recovery) was measured followed by positive fusional vergence (PFV) ranges (blur, break and recovery). Results: Pearson correlations were calculated and showed no correlations between vergence facility and any of fusional vergence measurements (p>0.05). Also, there were no significant differences of vergence facility measurements on the compensating vergence that passed or failed Sheard and Morgan's criterion for comfortable vision (p>0.05). Conclusions: There was no correlation between vergence facility and fusional vergence among symptomatic subjects. Hence, both vergence facility and fusional vergence should be assessed for those with binocular dysfunction in order to make an accurate diagnosis and management plan.

• Water for future
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• v.15 no.2
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• pp.11-22
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• 1982

This study is to find out the reasonable drainage system of sewerage in connection with the geographical conditions, the form of city, and the problem of sewerage in and around Seoul. (1) In supplying the sewerage sewer, the separating system is desirable in connection with the problem of sewerage disposal in future. However, in the existing urban district, the conjunction system is used because of the large amount invested according to the diversion of the sewer of the separation system and the influence of the traffic communication. The sewer of the separating system should be used in the case of the fundamental reconstruction of structure as the redevelopment of the urban district or the subway and new-development of area. Therefore, the separating system should be used completely until the goal year. (2) Drainage area was divided for the natural flowing, considering that the 38 streams and topography paly a role of the main stream of drainage. There are the branches, Guyui, Dug-island, Jayang, Hannam, Banpo, Amsa whose divisions are impossible. In these branches, the drain planning was suggested a forced control method by using the exiting pond age and the pumping station. (3) The best available method which improbes the water quality in Han river is as follows. The sewerage is catched and carried to the sewerage disposal plant by establishing the intercept sewer in both or one side of stream. At the same time, the groudwater volume which springs in each stream is drained separatively.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.6
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• pp.599-609
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• 2008

Development of computer and electronic technology leads innovative progress in spatial informatics and successful commercialization. Geospatial information technology plays an important role in decision making in various applications. However, information display media are two-dimensional plane that limits visual perception. Understanding human visual processing mechanism to percept stereo vision makes possible to implement three-dimensional stereo image display. This paper proposes on-the-fly stereo image generation methods that are involved with various exterior and camera parameters including exposure station, viewing direction, image size, overlap and focal length. Collinearity equations and parameters related with stereo viewing conditions were solved to generate realisitc stereo imagery. In addition stereo flying simulation scenery was generated with different viewing locations and directions. The stereo viewing is based on the parallax principle of two veiwing locations. This study implemented anaglyphic stereogram, polarization and lenticular stereo display methods. Existing display technology has limitation to provide visual information of three-dimensional and dynamic nature of the real world because the 3D spatial information is projected into 2D plane. Therefore, stereo display methods developed in this study improves geospatial information and applications of GIS by realistic stereo visualization.

• Journal of the Korean Geographical Society
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• v.36 no.2
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• pp.111-125
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• 2001

An estuary is semi-inclosed inlets, located between terrestrial and marine environment. Since many estuaries along south-western coasts of Korean peninsula were affected by human settlements and activities, significant changes in sedimentation environments have been observed. The research area is divided into three distinct morpho-stratigraphic units: fluvial dominated area(Area1), mixed area(Area 2), tide-dominated area(Area3). The landform of this area has been changed by reclamation and river channel change. Temporal variations affected by dam construction, periodic freshet was iterrupted. Sediments began to continuously accmulate on estuary banks by tide. Meanwhile, because of the continuous but reduced discharge of fresh water, the salinity of estuarine sediments was declined. That processes made vegetated area( Phregmites lonivalvis and Suaeda japonica) to be expanded. It indicates that the magnitude and frequency of geomorphic processes has been significantly changed.