• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.301-307
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• 2011

Optimal culture conditions of Spirulina platensis NIES 39 have been established using different types of light sources. Several types of photobioreactors were designed and the increase of biomass, the amount of $CO_2$, fixation and the production of chlorophyll content were studied. The result revealed that the input conditions of a 10 min period per 4 h at the condition of 5% $CO_2$ and 0.1 vvm, were excellent in the growth. The growth showing the maximum biomass accumulation is limited to 1.411 g/L when using the fluorescent bulb and the low powered surface mount device (SMD) type LEDs which were equipped-inside in the photobioreactor. However, the biomass exceeded up to 1.758 g/L level when a high powered red LED (color temperature : 12000 K) photobioreactor system was used. The $CO_2$ fixation speed and rate were increased. Although the total production of chlorophyll content undergoes a proportional increase in the biomass, the net content per dry cell weight (DCW) showed the higher production with a blue LED (color temperature : 7500 K) light than that of any other wavelengths. The carbon dioxide loss was marked as 0.15% of the inlet gas (5% $CO_2/Air$, v/v) at the maximum biomass culture condition.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.2
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• pp.133-139
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• 2011

We have performed optical design of light guide plates (LGPs) for a photobioreactor by using an illumination design tool. An LGP having light emitting diodes (LEDs) as a light source on the four sides was designed by optimizing the distribution of LGP patterns and design of another LGP, on top of which sunlight was focused by a Fresnel lens, was executed. Finally, a hybrid-solar-and-LED-lighting scheme was described. Detailed design process and optical performances of the designed LGPs are presented.

• Journal of Korean Society on Water Environment
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• v.29 no.2
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• pp.270-275
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• 2013

The aim of this study was to investigate the efficiency of thickness of optical panel (OP) on the growth rate of Chlorella vulgaris. The size of Chlorella vulgaris (FC-16) was $3-8{\mu}m$, having round in shape. The cells of Chlorella vulgaris was cultured in the Jaworski's Medium with deionized water at $22^{\circ}C$ for 15 days. For this experiment, three OP samples were prepared to evaluate the efficiency of thickness of OP on the growth rate of Chlorella vulgaris; 4 mm OP with LED (Light Emitting Diode) (Run 1), 6 mm OP with LED (Run 2) and 8 mm with LED (Run 3). The diffuse rate was reached 86%, 91% and 92% for Run 1, Run 2 and Run 3, respectively. Average biomass of Run 2 and Run 3 were measured 11.18% higher than that of Run 1. However, the specific growth rate for all fractions were almost same. In addition, chlorophyll content per cell and cell volume were found to be slice difference between Run 2 and Run 3. Therefore, Run 2 has more effect on growth rate of biomass for Chlorella vulgaris than Run 1 and Run 3.

• Korean Journal of Optics and Photonics
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• v.27 no.2
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• pp.73-80
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• 2016

In this paper, we report the results of a study on the design and fabrication of a light-guiding plate (LGP) using a hybrid light-emitting diode (LED) and sunlight source that can be applied to a photobioreactor. LGP patterns for the LED source were designed and engraved on an LGP, together with previously reported patterns for a sunlight source. A control system for the hybrid LGP was designed to maintain the output photon flux density (PFD) from the LGP at a constant value. When the target value of the output PFD was set to $70{\mu}E/(m^2{\cdot}s)$, the error range of the output PFD was found to be within ${\pm}2%$.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.7
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• pp.467-472
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• 2012

The aim of this study was to investigate the efficiency of optical panel (OP) on the growth rate of Chlorella vulgaris (C. vulgaris). The size of C. vulgaris (FC-16) was 3~$8{\mu}m$, having round in shape. The cells of C. vulgaris was cultured in the Jaworski's Medium with deionized water at $22^{\circ}C$ for 15 days. For this experiment, three light samples were prepared to evaluate the efficiency of OP on the growth rate of C. vulgaris; OP with LED (Light Emitting Diode) (Run 1), Fluorescent light (Run 2) and LED (Run 3). The specific growth rate of C. vulgaris for Run 1 was found to be 14 times and 5 times faster than Run 2 and Run 3, respectively. In addition, the average biomass of C. vulgaris for Run 1 was measured 11.79 g/L in 11 days. This means that the biomass for Run 1 was reached 30 times and 6.5 times higher than Run 2 and Run 3, respectively. This may be due to the fact the OP was increased the light uniformity and hindered the shading effects in photobioreactor. Therefore, the growth rate of biomass in photobioreactor with OP is compared better than the without OP used other photobioreactor.

• Korean Journal of Optics and Photonics
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• v.23 no.2
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• pp.55-63
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• 2012

We present results of optical design and fabrication of a light guiding plate (LGP) to be used as an illumination system for photobioreactors. Modeling of a light-emitting diode (LED) light source, a reflection film, and LGP patterns was performed. Especially, the LGP patterns were modeled as Lambertian scatterers. The modeling parameters (reflectance, scatterer width) were determined through matching simulations with the experimentally measured illuminance distribution for a test LGP. An LGP for an LED light source was designed with the extracted model parameters, and fabricated using a computerized numerical control machine. Optical characteristics including average illuminance and uniformity of illuminance distribution were measured for the fabricated LGP.

• Korean Chemical Engineering Research
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• v.52 no.1
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• pp.8-16
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• 2014

Microalgae have been considered as a promising microorganism in the field of bio-industry due to their abilities to fix carbon dioxide as well as biosynthesize valuable secondary metabolites. Of many lighting sources for microalgal cultivation, LED (Lighting Emitting Diode) has been emerged as the appropriate choice with multiple advantages over the conventional bulbs. However, it is only in recent years that we have witnessed the possibility of application of LED into microalgae cultivation system. LED will serve as an evolutionary lighting source for microalgae cultivation system and open the frontier for integrative bio-industries. In this paper, we present the comprehensive review on the recent trends of LED applications into microalgal biotechnology.

• Clean Technology
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• v.6 no.1
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• pp.71-78
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• 2000

Removal rates of hydrogen sulfide were investigated to known effects of several light sources with external and internal irradiation on the desulfurization using C. thiosulfatophilum. In the case of internal illumination system, optical-fiber photobioreactor was applied to increase the light availability. Furthermore, sunlight was used as the main light energy in the daytime and metal-halide lamp was applied as an additional light energy at night. Light energy of 99% was saved by the application of the LED's array in comparison with the incandescent light source. $H_2S$ removal rates at 5,000 lux in a 4-L photobioreactor were shown as 0.040, 0.138, 0.136, and 0.134 (${\mu}mol$ $H_2S/min$)/(mg protein/L), respectively, in the following order of light sources, when several light sources such as fluorescent, energy-saving, incandescent, halogen lamp, and filtered light at 460 nm were applied. Removal rate per unit cell concentration with the internal light diffused optical-fibers increased about 1 six times as much as that with the external light sources. Removal rate per unit cell concentration, using sunlight in the daytime and a metal-halide lamp at night, was 0.41 less than 0.869 (${\mu}mol$ $H_2S/min$)/(mg protein/L) using a 400 W metal-halide lamp day and night, since the automatic sunlight collection system can transmit the light intensity as only 10% of that with a metal-halide lamp.

• Journal of the Korean GEO-environmental Society
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• v.13 no.2
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• pp.41-47
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• 2012

The purpose of this study was to determine optimum condition for the cultivation of Chlorella sp. FC-21 using red light emitting diodes (LED). Specific growth rate and cell concentration were measured for the reactors at the illuminations of different light intensity of red LED. Under the illumination of red LED, specific growth rate increased as light intensity increased but cell concentrations decreased. To determine beneficial effect of aeration to cell cultivation, micro-air bubbles were aerated at 0.7 vvm in the reactor at the illumination of red LED. Two and ten times greater specific growth rate and cell concentration were obtained when aeration was applied. In case of blowing of carbon dioxide, pH of culture medium decreased below to pH 3, which resulted in decreases of cell concentration. From this study, we found that red LED with aeration were the most appropriate light source for the cultivation of Chlorella sp. FC-21.

• KIEAE Journal
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• v.17 no.1
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• pp.43-48
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• 2017

Purpose: Building owners or residents have concerns to strive for energy-saving and environmental conservation by utilizing with eco-friendlier energy resources for their physical environment. In this paper, an algae façade system is proposed as an energy-friendly building component to improve energy productivity and indoor environmental quality, and this study aims at verifying alternative technologies for implementing building elevations that contain various colors equipped with algae façade systems and suggesting design guidelines to enhance both building performance and design values. Method: The color of algae is basically ranged about the saturation green, and it is hardly converted to other variations. Such a problem can be resolved through the artificial lights like LED (Light Emitting Diode) lamps to mix the color from the algae and buildings could possibly change the elevation in many ways under the influence of daylight. Result: As a result, the suggested system may increase the aesthetic aspect of the building in response to environmental changes. The system cannot possibly be applied for only new construction, but also it can be utilized with the existing buildings as well. The proposed system is expected to be applied not only a new construction and any existing buildings as well, and it will cover from the environmentally friendly energy generation in the industry to a new application system for increasing energy efficiency and the beauty of building envelopes.