• Journal of the Korean Society for Precision Engineering
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• v.31 no.1
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• pp.21-28
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• 2014

Recently, several researchers made their endeavor to manufacture the photobioreactor(PBR) with characteristic shapes form vacuum and blow forming process. Hence, behaviors of the transparent polycarbonate(PC) plate in the high temperature region should be examined to obtain the desired PBR case via vacuum and blow forming processes. The aim of this paper is to investigate tensile behavior of PC plate in the high temperature. Various tensile tests were performed using high temperature tensile testing machine. The influence of tensile speed, thickness and ambient temperature on tensile behavior in the high temperature was examined. The flow stress and tensile strength augmented when the tensile speed increased. In order to obtain proper flow curves with strain rate effects for different temperature of specimen, G'sell-Jonas model was adopted. The material constants of the G'sell-Jonas model were estimated. The flow curves of the PC plate considering the tensile speed, specimen thickness and temperature were obtained.

• Journal of Microbiology and Biotechnology
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• v.12 no.6
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• pp.962-971
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• 2002

The current study proposes a simple monodimensional model to estimate the linear growth rate of photosynthetic microorganisms in flat-plate photobioreactors (FPPBRs) during batch cultivation. As a model microorganism, Chlorella kessleri was cultivated photoautotrophically in FPPBRs using light-emitting diodes (LEDs) as the light sources to provide unidirectional irradiation in the photobioreactors. Various conditions were simulated by adjusting both the intensity of the light and the height of the culture. The validity of the proposed model was examined by comparing the linear growth rates measured with the predicted ones obtained from the proposed model. Accordingly, the value of $\frac{K\cdot\mu m}{\alpha\cdot L}log(I_0\cdot{I_s}^{\varepsilon 1)\cdot {I_c}^{-\varepsilon})$ was proposed as an approximate index for strategies to obtain the maximal lightn yield under light-limiting conditions for high-density algal cultures and as a control parameter to improve the photosynthetic productivity and efficiency.

• 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.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.2
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• pp.111-118
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• 2020

Recently, bioenergy research using microalgae, one of the most promising biofuel sources, has attracted much attention. Cell disruption, which can be classified as physical or chemical, is essential to extract functional ingredients from microalgae. In this study, we investigated the cell disruption efficiency of Chlorella sp. using low-frequency non-focused ultrasound (LFNFU). This is a continuously physical method that is superior to chemical methods with respect to environmental friendliness and low processing cost. A flat panel photobioreactor was employed to cultivate Chlorella sp. and its growth curve was fitted both with Logistic and Gompertz models. The temporal change in cell reduction by cell disruption using LFNFU was fitted with a Logistic model. The experimental conditions that were investigated were the initial concentration of microalgal cells, relative amplitude of output ultrasound waves, processing volume of microalgal cells, and initial pH value. The optimal conditions for the most efficient cell disruption were determined through the various tests.

• Journal of Korean Society on Water Environment
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• v.30 no.6
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• pp.647-652
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• 2014

The aim of this study was to investigate the heavy metal removal and biomass productivity in the Acid Mine Drainage (AMD) using eggshell and microalgae. The experiment was operated 6 days in the eggshell and microalgae hybrid system, and using eggshell powder and microalgae as Chlorella vulgaris. The obtained result indicated that the biomass productivity of 2.82 g/L/d from 1.12 g/L initial concentration in 6 days was reached with light transmittance of 97% at a 305 mm depth in the optical panel photobioreactor (OPPBR). The total removal efficiency of Fe, Cu, Zn, Mn and Cd was found to be 98.92%, 99.91%, 98.78%, 88.99% and 98.00% in the AMD using eggshell and Chlorella vulgaris hybrid system, respectively. Additionally, there were significant relationships between biomass and concentration of each heavy metal ($R^2$ = 0.8771, 0.8643, 0.8669, 0.9134 and 0.6277 for Fe, Cu, Zn, Mn and Cd). These results indicated that the eggshell and microalgae hybrid system was highly effective for heavy metal removal when compared to the conventional biological process in the AMD. Therefore, the eggshell and microalgae hybrid system was effective for heavy metal removal and biomass productivity and can be applied to treat AMD in treatment plant.

• Journal of Korean Society on Water Environment
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• v.30 no.5
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• pp.469-476
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• 2014

The focus of this study was to observe the growth of Chlorella sp., Nannochloris sp., and Botryococcus braunii under mixotrophic conditions (i.e., added glycerol) with the aim of increasing the growth of biomass and algae oil content. A significant growth of biomass was obtained when grown in glycerol rich environment comparing to autotrophic conditions. 5 g/L glycerol yielded the highest biomass concentration for these strains. Mixotrophic conditions improved both the growth of the microalgae and the accumulation of triacylglycerols (TAGs). The maximum amount of TAG in Botryococcus braunii was reached in the growth medium with 10 g/L glycerol and Chlorella sp., Nannochloris sp. with 2 g/L glycerol. The content of saturated fatty acids of Chlorella sp., Nannochloris sp., and Botryococcus braunii was found to be 34.94, 14.23 and 13.39%, and the amount of unsaturated fatty acids was 65.06, 85.78 and 86.61% of total fatty acids, respectively. The fatty acid profiles of the oil for the culture possibility met the necessary requirements and are, therefore, promising resource for biofuel production.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.9
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• pp.946-957
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• 2012

The objective of this paper is to investigate into the development of a thin flat panel photo-bioreactor case with characteristics shapes. The thin flat panel photo-bioreactor case was designed to be manufactured from a plastic thermoforming process. A proper design with a relatively high rigidity was obtained through the structural analyses for different designs of the photo-bioreactor case. The thermoforming analyses were performed. From the results of the thermoforming analyses, a proper forming condition and the formability of the designed plastic photo-bioreactor case were estimated. The thermoforming moulds for the flat panel photobioreactor cases were manufactured. The thermoforming experiments were performed to examine the manufacturability of the designed flat panel photo-bioreactor cases. From the results of the thermoforming experiments, it was shown that thin flat panel photo-bioreactor cases with characteristic shapes can be manufactured from the designed thermoforming mould and process.

• Journal of Life Science
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• v.7 no.4
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• pp.377-383
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• 1997

The acute toxicity effect of triorganotin of trioganotin on the growth of microalgae and shellfish was investigated through flask culture. The value of 120 hr-LC$_{50}$ that is the median lethal concentration of TBTO on the shellfish (R. philipinarum) was found to be 6 $\mu$g/L. The acute toxicity effect of TBTO on T. suecica was obviously shown even at the concentration of 0.5 $\mu$g/L, and the effect diminished as the initial cell density increased. The effect also diminished less in the experiment done under aeration than in that done under non-aeration. To design a chemostat system for the test of chronic toxicity, the culture of T. suecica was executed in photobioreactor. In batch culture, the profiles of chlorophyII a and D.C.W. showed the growth of T. suecica very well, and the maximum specific growth rate was estimated to be 0.54 d$^{-1}$. with this value, as a dilution rate in contimuous culture, pH was nicely maintained between 7 and 9 when air was supplied with 3% CO$_{2}$. From all results and the natural environment of clam, a novel chemostat system was invented. Through this system, we can observe each independent toxicity effect of TBTO and plankton and combined toxicity effect as well.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.8
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• pp.33-41
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• 2021

Recently, many studies have been conducted on substituting fossil fuels with bio-refineries in existing industrial systems using biomass. Among the various bio-refineries, microalgae have received wide attention because it uses inorganic compounds to produce useful substances, which are extracted by a cell disruption process. Although numerous cell disruption methods exist, cell disruption efficiency has been studied by ultrasonic treatment. Ultrasound is a high-frequency (20 kHz or higher) sound wave and causes cell disruption by cavitation when passing through a solvent. In this study, we used the microalgal species Chlorella sp., which was cultured in a plate-type photobioreactor. The experiment was conducted using a continuous low-frequency processing device. The reduction of cells with time due to cell disruption was fitted using a logistic model, and optimum conditions for highly efficient cell disruption were determined by conducting experiments under multiple conditions.

• Journal of the Korean GEO-environmental Society
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• v.12 no.12
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• pp.31-35
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• 2011

The purpose of this study was to determine optimum condition for the cultivation of Chlorella sp. FC-21, which is a freshwater microalgae, using light emitting diodes (LEDs). Specific growth rate and cell concentration were measured for the reactors at the illumination of different wavelengths of LEDs. Among various types of LEDs, red LEDs were the most effective light source, and also greatest increases of specific growth rate and cell concentrations were obtained when light intensity of red LEDs increased. From this study, we found that red LEDs were the most appropriate light source for the cultivation of Chlorella sp. FC-21.