• Proceedings of the KSRS Conference
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• v.1
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• pp.471-474
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• 2006

Several planktonic dinoflagellates, including Cochlodinium polykrikoides (p), are known to produce red tides responsible for massive fish kills and serious economic loss in turbid Northwest Pacific (Korean and neighboring) coastal waters during summer and fall seasons. In order to mitigate the impacts of these red tides, it is therefore very essential to detect, monitor and forecast their development and movement using currently available remote sensing technology because traditional ship-based field sampling and analysis are very limited in both space and temporal frequency. Satellite ocean color sensors, such as Sea-viewing Wide Field-of-view Sensor (SeaWiFS), are ideal instruments for detecting and monitoring these blooms because they provide relatively high frequency synoptic information over large areas. Thus, the present study attempts to evaluate the red tide index methods (previously developed by Ahn and Shanmugam et al., 2006) to identify potential areas of red tides from SeaWiFS imagery in Korean and neighboring waters. Findings revealed that the standard spectral ratio algorithms (OC4 and LCA) applied to SeaWiFS imagery yielded large errors in Chl retrievals for coastal areas, besides providing false information about the encountered red tides in the focused waters. On the contrary, the RI coupled with the standard spectral ratios yielded comprehensive information about various ranges of algal blooms, while RCA Chl showing a good agreement with in-situ data led to enhanced understanding of the spatial and temporal variability of the recent red tide occurrences in high scattering and absorbing waters off the Korean and Chinese coasts. The results suggest that the red tide index methods for the early detection of red tides blooms can provide state managers with accurate identification of the extent and location of blooms as a management tool.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.3
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• pp.207-215
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• 2002

Ocean color properties can be quantified by the relationship between the band ratios of the sensor on the ocean color satellites and the measured field ocean color parameters, A tool to determine the abundance of primary organism using the observed ocean color properties from satellite is presented. Coincident to ocean color satellite passes over the Korean waters, the research vessels were deployed to survey the East Sea, the South Sea and the West Sea around the Korean waters, We have been able to have more than 101) data sets containing coincident in situ chlorophyll a and the estimated chlorophyll a derived from SeaWiFS (Sea-viewing Wide Field-of-view Sensor) from february, 1999 to October, 2001. We were able to develop three proper regional algorithms for the East Sea, the South Sea and the West Sea of the Korean peninsula to estimate chlorophyll a, and set up regional algorithms to quantify the suspended solid in the southern sea of the Korean peninsula, Futhermore we were successful in finding out a simple way of estimating chlorophyll a in the turbid water (Case 2 water) using the relationship between in situ chlorophyll a and the estimated chlorophyll a from the processed level 2 data, using the NASA's global algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3429-3434
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• 2014

In the TFT-LCD(Thin Film Transistor-Liquid Crystal Display) panel manufacturing industry, SAMSUNG, a late entry, can catch up to leading first mover, SHARP. The changes the note, monitor, TV, and mobile markets in the TFT-LCD industry were studied using a system analysis method. In addition, the fast response time technology in SAMSUNG TFT-LCD technology was developed using the TRIZ method. For example, a new liquid crystal mixture of a wide view angle and fast response time were developed by doping a new high birefringence liquid crystal material in a base mixture using the contradiction method and su-field method of TRIZ. The response time of a new liquid crystal mixture was improved to approximately 60%(16.2ms with base LC mixture, 9.8ms with a new LC mixture).

• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.2
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• pp.62-72
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• 1998

The purpose of this study is to suggest objective basic data for environmental resource planning through the evaluation of the visual quality by GIS. For this, Landscape information system have been made up of topographical and superficial information and landscape values of Cheju Island have been evaluated by using Grass 4.1, degree of visual preferences have been measured mainly by questionnaires and finally these data have been analyzed by using the correlation. Result of this study can be summarized as fellows, in the landscape value, remarkable views play a role as the dominant landscape information. Also, LCPs including various, successive view or a lot of visibility amount have high Landscape value. Therefore, it is important to management landscape which can preserve values of landscape elements through the creation of visibility area. In the visual preference, remarkable scenes play a part as a dominant factor. Also, LCPs including a wide field of vision or successive view have high visual preference. Therefore, it is proved that the visual preference is related to a field of vision and remarkable scenes. Finally, these data have been analyzed by using the regression, in order to verify the method. The result is that a R\sup 2\ is 0.715. It means that correlation is significant at the 0.01 level. In conclusion, the results of this study reveal that visual preference has been evaluated by aesthetic variables and landscape values have been evaluated by GIS. And visual preference and landscape values are closely correlated. In other words, it is possible to evaluate the aesthetic value by physical variable. The method of evaluationi is used in Cheju Island, and it will be possible to apply this method to other places. And this method can be applied to other places by special quality and landscape informatioin system, made up of landscape elements. Also, it will be possible to keep up management and applicatioin that is evaluated by GIS and computer program. Recently, there is a tendency tat visual and aesthetic approach, based on planners' experiences and intuitioin is gradually changed to the scientific approach, based on a objective data. Therefore, it is important that the measuring system is based on objective data which are concerned with a special quality of landscape. It is also significant that the environmental planning is based on a spatial image of physical environment and major landscape elements.

• Korean Journal of Optics and Photonics
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• v.34 no.4
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• pp.157-169
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• 2023

Augmented reality (AR) using a head mounted display (HMD) is used in various fields such as military, medicine, manufacturing, gaming, and education. In this paper, we discuss the design and fabrication of the AR optical system, which is most essential for HMD. The AR optical system for HMD requires a wide transparent area in which the augmented image of the display and the real world can be viewed at the same time. To this end, an AR optical system was designed and manufactured by dividing it into three parts according to each characteristic. Also, the refractive index of the ultra-violet (UV) adhesive layer required to make the three optical systems into one complete AR optical system was considered from the design stage to minimize the optical path shift phenomenon when the input light source passes through the UV adhesive layer. In addition, when designing the AR optical system, two aspheric surfaces were used to compensate for off-axis aberration and to be suitable for mass production. Finally, for HMD mass production, an aspheric AR optical system with a thickness of 11 mm, a diagonal field of view of 40°, and a weight of 11.3 g was designed and manufactured.

• Journal of radiological science and technology
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• v.46 no.4
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• pp.315-323
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• 2023

Post-mortem computed tomography (PMCT) is commonly employed in the field of forensic pathology. PMCT was mainly performed using a whole-body scan with a wide field of view (FOV), which lead to a decrease in spatial resolution due to the increased pixel size. This study aims to evaluate the potential for developing a super-resolution model based on conditional generative adversarial networks (CGAN) to enhance the image quality of CT. 1761 low-resolution images were obtained using a whole-body scan with a wide FOV of the head phantom, and 341 high-resolution images were obtained using the appropriate FOV for the head phantom. Of the 150 paired images in the total dataset, which were divided into training set (96 paired images) and validation set (54 paired images). Data augmentation was perform to improve the effectiveness of training by implementing rotations and flips. To evaluate the performance of the proposed model, we used the Peak Signal-to-Noise Ratio (PSNR), Structural Similarity Index Measure (SSIM) and Deep Image Structure and Texture Similarity (DISTS). Obtained the PSNR, SSIM, and DISTS values of the entire image and the Medial orbital wall, the zygomatic arch, and the temporal bone, where fractures often occur during head trauma. The proposed method demonstrated improvements in values of PSNR by 13.14%, SSIM by 13.10% and DISTS by 45.45% when compared to low-resolution images. The image quality of the three areas where fractures commonly occur during head trauma has also improved compared to low-resolution images.

• Korean Journal of Optics and Photonics
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• v.31 no.6
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• pp.281-289
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• 2020

This paper reports a slim mobile lens design using a hybrid refractive/diffractive optical element. Conventionally a wide field of view (FOV) camera-lens design adopts a retrofocus type having a negative (-) lens at the forefront, so that it improves in imaging performance over the wide FOV, but with the sacrifice of longer total track length (TTL). However, we chose a telephoto type as a baseline design layout having a positive (+) lens at the forefront, to achieving slimness, based on the specification analysis of 23 reported optical designs. Following preliminary optimization of a baseline design and aberration analysis based on Zernike-polynomial decomposition, we applied a hybrid refractive/diffractive element to effectively reduce the residual chromatic spherical aberration. The optimized optical design consists of 6 optical elements, including one hybrid element. It results in a very slim telephoto ratio of 1.7, having an f-number of 2.0, FOV of 90°, effective focal length of 2.23 mm, and TTL of 3.7 mm. Compared to a comparable conventional lens design with no hybrid elements, the hybrid design improved the value of the modulation transfer function (MTF) at a spatial frequency of 180 cycles/mm from 63% to 71-73% at zero field (0 F), and about 2-3% at 0.5, 0.7, and 0.9 fields. It was also found that a design with a hybrid lens with only two diffraction zones at the stop achieved the same performance improvement.

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.354-360
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• 2005

A high performance LWIR(long wavelength infra red) zoom thermal imaging sensor using $480{\times}6$ HgCdTe(MCT) linear detector has been developed by ADD Korea. The optical system consists of zoom telescope having large objective about 190 mm diameter and optically well corrected scanning system. The zoom ratio of the telescope is 3: 1 and its magnification change is performed by moving two lens groups. And also these moving groups are used for athermalization of the system. It is certain that the zoom sensor can be used in wide operating temperature range without any degradation of the system performance. Especially, the sensor image can be displayed with the HDTV(high definition television) format of which aspect ratio is 16:9. In case of HDTV format, the scanning system is able to display 620,000 pixels. This function can make wider horizontal field of view without any loss of performance than the normal TV format image. The MRTD(minimum resolvable temperature difference) of the LWIR thermal imaging sensor shows good results below 0.04 K at spatial frequency 2 cycles/mrad and 0.23 K at spatial frequency 8 cycles/mrad at the narrow field of view.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.42.1-42.1
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• 2011

The main payload of the Science and Technology Satellite 3 (STSAT-3), Multipurpose Infrared Imaging System (MIRIS), will be equipped with the wide-field near-infrared camera. Its wide field-of-view ($3.67^{\circ}{\times}3.67^{\circ}$) is optimal for the observation of the zodiacal light (ZL), the sunlight scattered by the interplanetary dust (IPD). The MIRIS will continuously monitor the seasonal variation of the ZL towards both north and south ecliptic poles, which is caused by the asymmetries of the IPD distribution with respect to the Sun and the ecliptic plane. In addition to the monitoring observations, we are planning pointed observations for compelling structures in the ZL, the asteroidal dust bands and the gegenschein. This presentation proposes the zodiacal light observations with the MIRIS and discusses the expected results.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.6
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• pp.578-586
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• 2005

Recently, due to the launch of digital broadcasting service, the demand of Flat Panel Display (FPD) is sharply rising. Among them, the PDP is expected to be one of the most promising digital displays of next generation because of its large screen size, high resolution, thinness and board field of view. Meanwhile, the PDP uses ADS (Address Display-period Separation) scheme which divide one subfield into address and sustaining period to express the grey scale of images. Since the output of sustaining power module Is mostly used for sustaining period, the load of the sustaining power module can be considered as a pulsating load. Due to this particular load condition, if the wide ZVS range of the power switches is not guaranteed, the hard switching causes large amount of switching loss and serious thermal problem in power module. In this paper, a high efficiency power conversion circuit for 60' PDP sustaining power module which achieves wide ZVS range with the help of additional ZVS tank is proposed. According to the various gating methods, the different operations of the proposed converter are presented. And, to confirm the properties of the proposed converter, an experimental prototype of 900W power converter is constructed md tested. As a result, more than $92\%$ of high efficiency is obtained at $10\%$ load condition, and the ZVS operation is achieved from full load to $10\%$ load condition.