• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.64-71
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• 2020

This study evaluated the effects of the culture media and light sources on the growth of microalgae Haematococuus pluvialis. Limited ingredient medium, Modified Bold's Basic Medium (MBBM), commercial liquid fertilizer medium Neo, and seven different light sources with different wavelengths were used to incubate H. pluvialis for 39 days, and the growth rates were compared. As a result, the growth of H. pluvialis, a limited ingredient medium, produced the highest cell growth in the fluorescent light source while cell growth was the lowest in the blue+red LED. The growth of H. pluvialis in commercial medium Neo was highest in the fluorescent light source, and cell growth was lowest in the blue LED. In this study, the MBBM culture medium showed better results than the Neo culture medium. Microalgae grown in the fluorescent light source using the MBBM culture medium showed the best cell growth result in this study. The results were optimized for the culture medium, light source, and light quantity in H. pluvialis culture for the production of secondary metabolites and provide basic data for the mass culture of microalgae.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.321-323
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• 2006

The light gets darker from center to edge of the light source. Therefore, we can find the center of the sun using shading histogram. Moreover, we can track the exact position of the sun with the shading histogram. In this paper, we propose a new technique using image-processing of digital camera, in order to locate the position of the sun.

• Women's Health Nursing
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• v.21 no.3
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• pp.197-206
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• 2015

Purpose: The purpose of this study was to examine the effects of light therapy on sleep disturbance and depression in climacteric women with menopausal symptoms. Methods: The research design was a nonequivalent control group pre test-post test design. Data were collected from September 29, 2013 to November 11, 2013. Participants included 17 climacteric women in an artificial light therapy group, 17 climacteric women in a sun light therapy group and 16 climacteric women in a control group. Measures consisted of the sleep disturbance, depression, melatonin, and serotonin. Results: There was a statistically significant difference of Korean Sleep Scale A (F=53.87, p<.001), and melatonin (F=31.19, p<.001) among three groups. There was a statistically significant difference of Self-Rating Depression Scale (F=121.86, p<.001), and serotonin (F=102.37, p<.001) among three groups. Conclusion: Artificial and sun light therapy can be applied as a supportive nursing intervention to subjects with sleep disturbance and depression in climacteric women with menopausal symptoms. Artificial and sun light therapy is expected to be a complementary alternative intervention for health management of the subjects with sleep disturbance and depression in climacteric women with menopausal symptoms.

• Journal of Environmental Science International
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• v.2 no.4
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• pp.279-289
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• 1993

Light qualities and three kinds of plant hormones, NAA, GA3 and BA were treated on maize seedlings to investigate the effect on formation of the chlorophyll-protein complexes. Each three kinds of plant hormones accelerated the chlorophyll proteins formation, particularly LHCP-1 and LHCP-3, but two kinds of hormonal combinations didn't promote these proteins accumulation under sun light condition. The formation of chlorophyll proteins of LHCP-1, CPA and LHCP-3 associated with PSII was promoted under red light compared to sun light, on the contrary the formation of chlorophyll proteins was not affected by white light. Plant hormones under red light induced chlorophyll proteins formation associated with PSII at early state of chloroplast development and two kinds of hormonal combinations under red light were very effective in accumulation of chlorophyll proteins of PSII in contrast to sun light. The results obtained suggest that light may play an important role compared to plant hormones in the formation of chlorophyll proteins.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.352-357
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• 2008

Using the artificial sun, namely the BIOSUN, we can control the sun light according to the latitude and longitude and for the seasonal changes and apply that to subway stations. By doing this, we can expect three effects, a. allowing the plants to grow inside the stations which will in turn contribute to improving air purity, controlling humidity, and reducing dust for pleasant environment, b. pleasant environment will foster positive emotional responses of the passengers and that would increase the satisfaction, and c. fostering good service for the citizenry and establishing an environmental friendly image of the Seoul Metro Subway System. The purpose of this thesis paper is to contemplate on the uses of the artificial sun powered by the microprocessor of a Light Emitting Diode (LED) in controlling the light and how the light can be utilized in facilitating photosynthesis that would allow plants to grow inside subway stations.

• Proceedings of the KSRS Conference
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• v.1
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• pp.274-277
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• 2006

KARI is currently developing a geostationary ocean color imager (GOCI) for COMS. We report the progress in integrated optical modeling and analysis for stray light suppression and the end-to-end instrument performance verification including in-orbit calibration. The Sun is modeled as the emitting light source and the selected area around Korean peninsular as the observation target that scatters the sun light towards GOCI in orbit. The optical ray tracing employing active geometric scaling was then used for precise characterization of the spatial and radiometric performance at the instrument focal plane. The analysis results show positive reduction in the simulated stray light level with the design improvement including baffles. It also indicates that the ray traced in-orbit radiometric performances are effective tools for the independent assessment of more traditional linear and quadratic equation based estimation of water leaving radiance. The concept of integrated GOCI optical model and the computational method are presented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.480-480
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• 2007

This paper performed the basic study for developing the light therapy equipment for medical treatment. We developed the equipment for medical therapy using a high brightness LED. This equipment was fabricated using a micro-controller and a high brightness LED, and designed to enable us to control light irradiation time, intensity, frequency and so on. Especially, to control the light irradiation frequency, and to control the change of output value, TLC5941 was used. Control stage is divided into 4 step by program. Consequently, the current value could be controlled by the change of level in Continue Wave(CW) and the output of a high brightness LED could be controlled, stage by stage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.70-77
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• 2020

Microalgae are independent organisms that perform photosynthesis and can alter the culture environment to increase accumulation of useful substances derived from microalgae. In this study, cell growth was measured by incubation for 39 days using MBBM, Neo medium, and seven light sources, which is the main factor affecting cell growth of microalgae S. obliquus. In the case of S. oliquus, which grew in MBBM and Neo medium, cell growth was highest under fluorescent light sources and Red2 LED (R660) light sources, and cell growth was lowest under Infra Red LED (R741) light sources. The average cell growth rate was 17.7% for MBBM and 15.4% for Neo. Comparing the effects of dry cell weight of Neo medium containing nutrients on the production of aquatic plants, MBBM and dry cell weight of Neo resulted in higher cell growth than Neo medium under all LED light sources except for Blue LED (B450). This proves that MBBM is more suitable for increasing the cell growth of microalgae than Neo medium and confirms that light source selection is important in the production of useful materials through mass cultivation of microalgae in the future.

• Korean Journal of Materials Research
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• v.24 no.6
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• pp.305-309
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• 2014

When sunlight irradiates a boron-doped p-type solar cell, the formation of BsO2i decreases the power-conversion efficiency in a phenomenon named light-induced degradation (LID). In this study, we used boron-doped p-type Cz-Si solar cells to monitor this degradation process in relation to irradiation wavelength, intensity and duration of the light source, and investigated the reliability of the LID effects, as well. When halogen light irradiated a substrate, the LID rate increased more rapidly than for irradiation with xenon light. For different intensities of halogen light (e.g., 1 SUN and 0.1 SUN), a lower-limit value of LID showed a similar trend in each case; however, the rate reached at the intensity of 0.1 SUN was three times slower than that at 1 SUN. Open-circuit voltage increased with increasing duration of irradiation because the defect-formation rate of LID was slow. Therefore, we suppose that sufficient time is needed to increase LID defects. After a recovery process to restore the initial value, the lower-limit open-circuit voltage exhibited during the re-degradation process showed a trend similar to that in the first degradation process. We suggest that the proportion of the LID in boron-doped p-type Cz-Si solar cells has high correlation with the normalized defect concentrations (NDC) of BsO2i. This can be calculated using the extracted minority-carrier diffusion-length with internal quantum efficiency (IQE) analysis.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.11
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• pp.1170-1173
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• 2012

We have investigated the LED lens eccentricity effect on light intensity distribution. For the purpose, we introduced an equation of focal length for paraboloid, and then made a comparative analysis of the theoretical result and 3-D simulation result.