• Journal of Environmental Science International
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• v.28 no.5
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• pp.521-526
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• 2019

In this study, a solar light collector that collects and transmits solar light required for crop production in a closed plant production system was developed. The solar light collector consisted of a Fresnel lens for collecting solar light, and a tracking actuator for tracking solar light from sunrise to sunset to increase the light collection efficiency. The optical fiber that transmitted solar light was made of Glass Optical Fiber (GOF), and it had an excellent optical transmission rate. After collecting the solar light, the amount of light was measured at 5, 10, 15, 20, 25, and 30 cm distances from the GOF through the darkroom by using a light sensor logger connected to a quantum and pyranometer sensor. Compared with solar light, the light intensity of pyranometer sensor measured at 5 cm was 114% higher than solar light, and 61% at 10 cm. In addition, it was observed that it is possible to transmit the necessary amount of light for growing crops up to about 15 cm (as over 22%) through GOF. Therefore, adding diffusers to the solar light collector should be expected to replace artificial light in plant factories or plug seedlings nurseries for leafy vegetables. More studies on the solar light collection devices and the light transmission devices that have high light collection efficiency should be conducted.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1999.11a
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• pp.80-84
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• 1999

Sunlight Collector System is a new way to make sunlight available to living things. It transmits sunlight through fiber optics to wherever is needs. It applies the artificial lighting, underground lighting, intelligent building, museum lighting, restoration-room to health etc. Cutting out most of the ultra-violet and intra-red radiation. In this paper, we measured the spectrum analysis of sunlight and Sunlight collector System's light. Also, we found out the distance to get visible light.

• Restorative Dentistry and Endodontics
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• v.17 no.2
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• pp.383-397
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• 1992

The purpose of this study was to evaluate the influence of artificial saliva contamination on bonding of several dentin adhesives to dentin. Sixty - three human molar teeth extracted within a month were used. Each tooth was sectioned longitudinally in a buccolingual direction to obtain 126 specimens. These specimens were randomly divided into three groups and were treated by Scotchbond 2, Gluma and All bond. Each group was subdivided into three subgroups; normal group not contaminated with artificial saliva, contaminated with artificial saliva and dried group, and contaminated with artificial saliva and washed and dried group. Enamel/dentin bonding agent(Dental Adhesive of Scotchbond 2) was applied and light cured on the treated dentin surfaces. Thereafter P - 50 were cured on them, and specimens were stored in $37^{\circ}C$ artificial saliva for 24 hours before measuring shear bond strength. Shear bond strengths were determined using an universal testing machine with cross head speed 1mm/min and SEM examinations were conducted to evaluate the resin - dentin interface and degree of penetrating resin string into the dentinal tubules. The following results were obtained. 1. Normal groups not contaminated with artificial saliva showed greater shear bond strength than any other group contaminated with artificial saliva(P<0.01). 2. The shear bond strengths showed no significant difference between washed groups with distilled water and not washed groups after contamination with artificial saliva(P>0.05). 3. In normal groups, the shear bond strength of A group was significantly greater than in any other group(P<0.01). 4. In Sand G groups, fractures after shear bond strength tests occured adhesively on resintooth interface in all specimens. But in A groups, fracture of the normal group occured cohesively in dentin and fracture of the contaminated groups occured adhesively and cohesively. 5. On SEM examination, the number of resin strings penetrated into dentinal tubules were the greatest in normal groups, followed by, in descending order, washed groups and not washed groups after contamination with artificial saliva.

• Journal of Bio-Environment Control
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• v.22 no.3
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• pp.228-233
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• 2013

This study was conducted to examine the effect of light intensity and photoperiod of white LEDs as the artificial light source on the growth of leaf lettuce (Lactuca sativa L.) 'Seonhong Jeokchukmyeon' in a closed-type plant production system. Seedlings, transplanted at a density of $20cm{\times}20cm$ in a completely randomized design, were grown under white LEDs (FC Poibe Co. Ltd., Korea), at one of the 3 light intensities (100, 200, or $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$), and each with one of 3 photoperiods [12/12, 18/6, or 24/0 (Light/Dark)]. Plants were cultured for 22 days under the condition of $21{\pm}2^{\circ}C$, $60{\pm}10%$ RH, and $400{\pm}50{\mu}mol{\cdot}mol^{-1}\;CO_2$. The greatest leaf length and width, fresh and dry weights, and total anthocyanin content were obtained in the 24/0 photoperiod, regardless of the light intensity. Length of the longest root, fresh and dry weights, and number of leaves were greater in light intensity of $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ than 100 or $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Chlorophyll value was the greatest in the photoperiod 12/12 than 18/6 or 24/0. The results obtained suggest that plant grew the best kept by light intensity at 200 or $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, and photoperiod of 12/12 or 18/6.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.4
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• pp.1-7
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• 2003

Artificial ground greening, which is considered as a way for the greening of cities, should be constructed easily and maintained continuously. Thus it is necessary to use light soils for keeping in flexible formation and light load. And the garden should be managed optimally taking account for the characteristics of the soil and plant. But in most landscape green area, they are not under management. Mostly they are occasionally irrigated without nutrient by hand-operating. So this study was conducted to investigate plant growth by management methods and soil depth(15cm, 30cm). As a results of the different methods of management had effect on the plant growth and on the rate of flowering. When Hosta longipes were grown in different three management methods, control(rainfall), periodical irrigation, and nutri-irrigation(fertigation), the content of chlorophyll, the plant growth and the rate of flowering were higher in nutri-irrigation (fertigation) treatment than those in control(rainfall) and periodic irrigation. And nutrient contents of leaf are also higher. Between 15cm and 30cm soil depth, the plant growth of 15cm soil depth is better than that of 30 soil depth. According to these results on artificial ground greening, determination of optimal soil depth by plant species is required, And a specialist for nutrient management is demanded.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.5
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• pp.212-217
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• 2015

Ships and marine structures have a lot of problems in their high maintenance and operating cost by biofouling. A biofouling occurrs by the adhesion of marine microorganism, algae and bacteria. In this study, the aim is to prevent or to reduce the biofouling phenomena through silver nano-particle coating on artificial light-weight aggregates and geopolymer. The antibacterial activity on them is tested according to ASTM E2149-2013a. The test results showed, it is estimated that silver nano-particles removed 99.99 % of bacteria. Specimens were set up in the sea side of field test area in Korea Institute of Ocean Science and Technology (KIOST) and have been observed for five months. The anti-biofouling effect and difference in weight change rate have been detected two months later after the installation. Because silver nanoparticles inhibit bacterial growth and kill the cells by destroying bacterial membranes, silver nano-particle coating on artificial lightweight aggregates is a well-suited and eco-friendly method for preventing biofouling in the sea up to 5 months.

• International Journal of Industrial Entomology and Biomaterials
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• v.35 no.2
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• pp.100-105
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• 2017

Under natural conditions, black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae), colonizes in warm temperate regions, and is active in Korea from May through October. Information on black soldier fly rearing, which is affected by seasonal factors in Korea, is limited. Oviposition by black soldier flies is dependent on light intensity and wavelength. Therefore, continuous mass rearing of this fly requires determination of optimal artificial conditions of illumination. In this study, we compared the number of eggs laid under an artificial light source (750 watt HPL lamp) versus nature sunlight. Our results showed that compared to oviposition under natural sunlight, the use of one or two lamps for 7 hours, resulted in only 43 and 76%, of the total number of eggs laid under natural sunlight, respectively. We also investigated the hatchability of oviposited eggs under artificial illumination and under natural sunlight. The hatching rate under the former was much significantly lower than under the latter. Further detailed research is required to develop methods for successful mass rearing of black soldier fly throughout the year by means of an indoor system.

• Journal of Ecology and Environment
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• v.46 no.3
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• pp.161-171
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• 2022

Background: Epilobium hirsutum L. is designated as an endangered plant in South Korea located in Asia, due to the destruction of its habitats through the development of wetlands. Therefore, in this study, in order to find a light condition suitable for the growth and ecophysiological responses of Epilobium hirsutum L., those of this plant under treatment with various light qualities in a smart farm were measured. Results: In order to examine the changes in the physiological and growth responses of Epilobium hirsutum L. according to the light qualities, the treatment with light qualities of the smart farm was carried out using the red light: blue light irradiation time ratios of 1:1, 1:1/2, and 1:1/5 and a red light: blue light: white light irradiation time ratio of 1:1:1. As a result, the ecophysiological responses (difference between leaf temperature and atmospheric temperature, transpiration rate, net photosynthetic rate, intercellular CO₂ partial pressure, photosynthetic quantum efficiency) to light qualities appeared differently according to the treatments with light qualities. The increase in the blue light ratio increased the difference between the leaf temperature and the atmospheric temperature and the photosynthetic quantum efficiency and decreased the transpiration rate and the intercellular CO₂ partial pressure. On the other hand, the white light treatment increased the transpiration rate and intercellular CO₂ partial pressure and decreased the temperature difference between the leaf temperature and the ambient temperature and photosynthetic quantum efficiency. Conclusions: The light condition suitable for the propagation by the stolons, which are the propagules of Epilobium hirsutum L., in the smart farm, is red, blue and white mixed light with high net photosynthetic rates and low difference between leaf temperature and atmospheric temperature.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.12
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• pp.27-33
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• 2011

This study aims to suggest some problems, which occur when environmental lighting zone is set by use-zone only, by comparing and analyzing the artificial illumination luminance. In addition, this study aims to review the control standards of light pollution and to suggest a practical environmental lighting zone-setting method. I checked out the standards of average surface luminance and luminance contrast as for light pollution management. In addition, I did some research on evaluation of light pollution on surroundings based on investigation of use-environment as for lighting environment setting method.

• Journal of the Semiconductor & Display Technology
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• v.18 no.4
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• pp.105-109
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• 2019

LED lighting is used as artificial lighting for plant growth because it has high light efficiency and can radiate light of various wavelengths. In this paper, we have developed new structure LED lighting module to improve the performance of LED lighting for plant growth and proposed a lighting control system that can be controlled wirelessly. The proposed LED lighting module was fabricated using optical lens applied to tunnel light and simulated using Relux program. Results of simulation, we confirmed that the light distribution and average illuminance of the proposed lighting were improved. LED lighting control system was developed to wirelessly control R, G, B, W LED lighting according to plant type and growing season. Therefore, it is expected to provide the optimal lighting environment for plant growth and contribute to the improvement of farm productivity and convenience.