• Korean Journal of Optics and Photonics
• /
• v.12 no.5
• /
• pp.376-381
• /
• 2001

We have fabricated a spectroadiometric system to measure spectral radiance of optical sources and evaluated its characteristics such as spectral responsivity, nonlinearity, and so on. The measurement system with PMT, Si, InGaAs, and IR-enhanced InGaAs detectors has shown a good linearity and a wide spectral responsivity of 250∼2500 nm. This spectroradiometric system will be used as the primary national standard system of spectral radiance measurements.

• Journal of Korean Ophthalmic Optics Society
• /
• v.20 no.3
• /
• pp.293-300
• /
• 2015

Purpose: To evaluate blue light hazards of LED lightings in an optical store with blue light radiance used as the quantitative indicators of photobiological hazard. Methods: The spectral radiance of each LED lightings was measured, and blue-light radiance and the corresponding maximum exposure time were calculated. Then each LED lighting was classified according to the risk group from IEC 62471 standard. Results: The yellow LED lightings used in showcases and white LED lightings used on ceilings and logo were classified into risk group RG0. But the white LED lightings used on showcases were classified into risk group RG1. The blue light radiances of white LED lightings used in showcases are dozens of times larger than that of fluorescent lamp. Conclusions: Using the value of the blue light radiance could quantitatively express the blue light hazard to various lightings. It was confirmed that white LED lightings for the showcases had high blue light hazards because of their high luminance and color temperature. Therefore, when replacing lightings in optical shop it is necessary to select the appropriate brightness and color temperature for eye health in the long term.

• Proceedings of the KSRS Conference
• /
• 1998.09a
• /
• pp.376-381
• /
• 1998

In this study, we was measured the radiance reflectance by using multi-spectral image of low resolution camera(LRC) which will be loaded in the multi-purpose satellite(KOMPSAT) to use the data in analyzing water pollution. Also we investigated the possibility of extraction of water quality factors in rivers and water body by using high resolution remote sensing data such as Airborne MSS. Especially, we tried to extract the environmental factors related with eutrophication, and also tried to develop the process technique and the radiance feature of reflectance related with eutrophication. The results were summarized as follows: First, the spectrum of sun's rays which reaches the surface of the earth was consistent with visible rays bands of 0.4${\mu}{\textrm}{m}$~0.7${\mu}{\textrm}{m}$ and about 50% of total quantity of radiation were there. And at around 0.5${\mu}{\textrm}{m}$ of green spectral band in visible rays bands, the spectrum was highest. Second, as a result of the radiance reflectance Chlorophyll-a represented high spectral reflectance mainly around 0.52${\mu}{\textrm}{m}$ of green spectral band, and suspended sediments and turbidity represented high spectral reflectance at 0.8${\mu}{\textrm}{m}$ and at 0.57${\mu}{\textrm}{m}$ each. Third, as a result of the water quality analysis by using Airborne MSS, Chlorophyll-a could have a distribution chart when carried out ratio of B3 and BS to B7. And Band 7 was useful for making the distribution chart of suspended sediments. And when we carried out PCA, suspended sediments and turbidity had distributions at PC 1 , PC 4 each similarly to ground truth data. Above results can be changed according to the change of season and time. Therefore, in order to analyze more exactly the environmental factors of water quality by using LRC data, we need to investigate constantly the ground truth data and the radiance feature of reflectance of water body. Afterward in this study, we will constantly analyze the radiance feature of the surface of water in water body by measuring the on-the-spot radiance reflectance and using low resolution satellite image(SeaWiFs). Besides, we will gather the data of water quality analysis in water body and analyze the pattern of water pollution.

• Korean Journal of Remote Sensing
• /
• v.15 no.2
• /
• pp.131-146
• /
• 1999

The satellite visible data have been successfully applied to study the ocean color. Another ocean color sensor, the Ocean Scanning Multi-spectral Imager (OSMI) on the Korea Multi-Purpose Satellite (KOMPSAT) will be launched in 1999. In order to understand the characteristics of future OSMI images, we have first discussed the simulation models and procedures in detail, and produced typical patterns of radiances at visible bands by using radiative transfer models. The various simulated images of full satellite passes and Korean local areas for different seasons, water types, and the satellite crossing equator time (CET) are presented to illustrate the distribution of each component of radiance (i.e., aerosol scattering, Rayleigh scattering, sun glitter, water-leaving radiance, and total radiance). A method to evaluate the image quality and availability is then developed by using the characteristics of image defined as the Complex Signal Noise Ratio (CSNR). Meanwhile, a series of CSNR images are generated from the simulated radiance components for different cases, which can be used to evaluate the quality and availability of OSMI images before the KOMPSAT will be placed in orbit. Finally, the quality and availability of OSMI images are quantitatively analyzed by the simulated CSNR image. It is hoped that the results would be useful to all scientists who are in charge of OSMI mission and to those who plan to use the data from OSMI.

• Korean Journal of Remote Sensing
• /
• v.20 no.5
• /
• pp.289-305
• /
• 2004

Atmospheric correction of Landsat Visible and Near Infrared imagery (VIS/NIR) over aquatic environment is more demanding than over land because the signal from the water column is small and it carries immense information about biogeochemical variables in the ocean. This paper introduces two methods, a modified dark-pixel substraction technique (path--extraction) and our spectral shape matching method (SSMM), for the correction of the atmospheric effects in the Landsat VIS/NIR imagery in relation to the retrieval of meaningful information about the ocean color, especially from Case-2 waters (Morel and Prieur, 1977) around Korean peninsula. The results of these methods are compared with the classical atmospheric correction approaches based on the 6S radiative transfer model and standard SeaWiFS atmospheric algorithm. The atmospheric correction scheme using 6S radiative transfer code assumes a standard atmosphere with constant aerosol loading and a uniform, Lambertian surface, while the path-extraction assumes that the total radiance (L/sub TOA/) of a pixel of the black ocean (referred by Antoine and Morel, 1999) in a given image is considered as the path signal, which remains constant over, at least, the sub scene of Landsat VIS/NIR imagery. The assumption of SSMM is nearly similar, but it extracts the path signal from the L/sub TOA/ by matching-up the in-situ data of water-leaving radiance, for typical clear and turbid waters, and extrapolate it to be the spatially homogeneous contribution of the scattered signal after complex interaction of light with atmospheric aerosols and Raleigh particles, and direct reflection of light on the sea surface. The overall shape and magnitude of radiance or reflectance spectra of the atmospherically corrected Landsat VIS/NIR imagery by SSMM appears to have good agreement with the in-situ spectra collected for clear and turbid waters, while path-extraction over turbid waters though often reproduces in-situ spectra, but yields significant errors for clear waters due to the invalid assumption of zero water-leaving radiance for the black ocean pixels. Because of the standard atmosphere with constant aerosols and models adopted in 6S radiative transfer code, a large error is possible between the retrieved and in-situ spectra. The efficiency of spectral shape matching has also been explored, using SeaWiFS imagery for turbid waters and compared with that of the standard SeaWiFS atmospheric correction algorithm, which falls in highly turbid waters, due to the assumption that values of water-leaving radiance in the two NIR bands are negligible to enable retrieval of aerosol reflectance in the correction of ocean color imagery. Validation suggests that accurate the retrieval of water-leaving radiance is not feasible with the invalid assumption of the classical algorithms, but is feasible with SSMM.

• Proceedings of the Korean Information Science Society Conference
• /
• 2000.10b
• /
• pp.490-492
• /
• 2000

전통적인 컴퓨터 그래픽스분야에서 실제감 있는 장면(scene)을 만들어 내기 위해 표면의 반사특성에 대한 연구가 많이 행해졌다. 표면의 반사특성을 구하기 위하여 기존의 방법들은 복잡한 기하학적 정보를 구하거나 실제 표면의 반사 특성을 얻기 위한 장치를 사용하였다. 본 논문에서는 기하학적 정보 없이 샘플링한 영상으로부터 라디안스맵(radiance map)을 만들고, 이를 이용하여 BRDF를 구하는 방법을 제시한다. 또한 BRDF를 효과적으로 저장하는 방법을 제시한다. 본 논문에서 제시한 방법을 사용하여 임의의 위치에서의 광원에 대하여서 조작이 가능하며 빠른 시간에 새로운 장면을 재구성(reconstruction)할 수 있다. 또한 사용자가 임의로 광원(color light)의 색깔을 변화시킬 수 있고, 여러 개의 광원(multiple light source)에 대하여 장면의 재구성이 가능하다.

• Journal of the Society of Naval Architects of Korea
• /
• v.47 no.3
• /
• pp.342-349
• /
• 2010

This paper is a foundation work in developing a software for generating infrared images from a scene with various objects. The spectral radiance received by a remote sensor is consisted of the self-emitted, reflected and scattered components. In general, the self-emitted component is the most important part for generating Infrared signatures from the object. In this paper, the infrared image generation considering various surface temperature and optical surface property of a flat plate is demonstrated in MWIR($3{\sim}5{\mu}m$) and LWIR($8{\sim}12{\mu}m$) regions for different spatial resolutions of the images. Resulting spectral radiance values in the MWIR($3{\sim}5{\mu}m$) and LWIR($8{\sim}12{\mu}m$) regions arrived at the infrared sensor are compared numerically and graphically by recognizing that they are strongly dependent on the surface conditions such as the surface temperature and the surface emissivity. And these infrared images are also shown to be strongly dependent on the resolutions of the infrared imaging devices as well. This study reveals that the surface conditions are more dependent on the radiance level from the surface while the resolution of the imaging device is more responsible for identifying the shape of object.

• Atmosphere
• /
• v.23 no.4
• /
• pp.453-470
• /
• 2013

As a part of the KIAPS Observation Processing System (KOPS), we have developed the modules of satellite radiance data pre-processing and quality control, which include observation operators to interpolate model state variables into radiances in observation space. AMSU-A (Advanced Microwave Sounding Unit-A) level-1d radiance data have been extracted using the BUFR (Binary Universal Form for the Representation of meteorological data) decoder and a first guess has been calculated with RTTOV (Radiative Transfer for TIROS Operational Vertical Sounder) version 10.2. For initial quality checks, the pixels contaminated by large amounts of cloud liquid water, heavy precipitation, and sea ice have been removed. Channels for assimilation, rejection, or monitoring have been respectively selected for different surface types since the errors from the skin temperature are caused by inaccurate surface emissivity. Correcting the bias caused by errors in the instruments and radiative transfer model is crucial in radiance data pre-processing. We have developed bias correction modules in two steps based on 30-day innovation statistics (observed radiance minus background; O-B). The scan bias correction has been calculated individually for each channel, satellite, and scan position. Then a multiple linear regression of the scan-bias-corrected innovations with several predictors has been employed to correct the airmass bias.

• Journal of Energy Engineering
• /
• v.26 no.1
• /
• pp.34-44
• /
• 2017

This paper deals with the effectiveness of a fiber optic solar lighting system that uses a Fresnel lens mounted on a two-axis solar tracker. A series of comparative analyses were made concerning its performance as compared to fluorescent lighting by using a simulation model based on ECOTECT and RADIANCE as well as referring to actual data. ECOTECT was used to model the test room (space) while RADIANCE was used for its indoor lighting conditions (environment). It was found that the average indoor light levels of fluorescent lighting fully satisfy the KS standard (KS A 3011, general office, class [G]: 300-400-600lux) whereas those of the solar lighting with light diffusers depends on the occlusion factor of roller shades installed on the south window.

• Journal of the Korean Applied Science and Technology
• /
• v.40 no.6
• /
• pp.1330-1339
• /
• 2023

In order to verify whether the serum using the medicinal plant Coptis japonica is effective in anti-aging of the skin, the improvement rate was analyzed by measuring the skin elasticity and radiance of the subjects, and the satisfaction was evaluated through a questionnaire. Twenty-two female subjects were given a serum containing 3% Coptis Japonica extract on one cheek for 4 weeks, and the test site was measured, and the skin elasticity increased by 5.73% from 0.8505 ± 0.0395 R2 (mm) before use to 0.8993 ± 0.0234 R2 (mm) after 4 weeks. Skin glow increased by 4.74% from 55.94 ± 5.49 (a.u.) to 58.59 ± 4.66 (a.u.), and the probability of significance was p<0.001, indicating a significant increase in the improvement rate of both items. It was found that all subjects were 100% satisfied with the improvement of elasticity and 95.5% satisfied with the improvement of radiance, and no skin abnormalities were found during the trial period. These results are expected to be used as basic data for future research and product development of anti-aging functional cosmetics using Coptis Japonica extract.