• 한국수산과학회지
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• 제45권6호
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• pp.694-703
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• 2012

To understand the characteristics of sedimentary and benthic environments in habitats of naturally-occurring intertidal benthic macroalgae, various geochemical parameters of sediment (grain size, ignition loss [IL], chemical oxygen demand [COD], and acid volatile sulfur [AVS]) and pore water (temperature, salinity, pH, and nutrients) were measured in the southern intertidal zone of Hampyeong Bay at two month intervals from April to October 2009. Ecological characteristics including the distribution and biomass of benthic macroalgae were also investigated. Benthic macroalgae were distributed below 4 to 5 m depth from mean sea level near the lower portion of the intertidal zone where air exposure time is relatively short. The distribution area and biomass of benthic macroalgae gradually decreased during the study period. The surface sediments in the benthic algal region were mainly composed of finer sediments, such as slightly gravelly mud and mud. The temperature, salinity, pH, and nutrient concentrations (except dissolved inorganic nitrogen) in pore water did not differ in regions with and without benthic macroalgae, whereas the mean grain size and the concentrations of IL, COD, and AVS in sediments were much higher in regions harboring benthic macroalgae. The correlation between mean grain size and IL in sediments displayed two distinct gradients and the slope was much steeper in regions harboring benthic macroalgae, indicating that the content of organic matter in benthic algal region is not solely dependent on mean grain size. Our results indicate that the benthic macroalgae in the southern intertidal zone of Hampyeong Bay play an important role in the accumulation of organic matter in sediment.

• 한국해양바이오학회지
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• 제10권2호
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• pp.91-96
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• 2018

There are many eutrophic lakes by point and non-point pollution sources such as in dustrial waste water, domestic raw sewage, and mucks. The eutrophic lakes not only cause algal blooms but also destroy the ecosystem in the lakes due to high nutrient concentrations. The purpose of this study was to improve water quality in eutrophic lakes by cultivating microalgae using photobioreactors (PBRs) with selectively permeable mesh (SPM), supplying nutrients in the lake and inhibiting cell leakage by diffusion and water permeability. Chlorella vulgaris, was cultivated using PBRs with SPM installed in Inkyung Lake located in Inha university, Incheon, Korea. When cultivating C. vulgaris, $8.3g/m^2/day$ of average biomass productivity was obtained at 3 days. Furthermore, concentrations of total nitrogen and phosphorus were reduced by 35.7% and 84.2%, respectively, compared to initial condition and water quality in eutrophic lake was improved to oligotrophic environment. These results suggest that microalgal cultivation using PBRs with SPM in the lake could produce microalgal biomass as well as improve water quality by decreasing nutrient concentrations.

• 한국해양학회지:바다
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• 제15권3호
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• pp.133-139
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• 2010

기장 연안 해조류의 해조상 및 군집 구조를 분석하기 위해서 2006년 8월과 2009년 8월에 연구를 수행하였다. 해조류는 녹조류 6종, 갈조류 10종, 홍조류 38종 등 총 54종의 서식이 확인되었다. 이 중 35종의 해조류가 각각의 조사 시기에 공통적으로 출현하였다. 평균 현존량은 2006년에 $616.0\;g\;m^{-2}$에서 $1,462.4\;g\;m^{-2}$였고, 2009년에는 $354.8\;g\;m^{-2}$에서 $965.6\;g\;m^{-2}$이었다. 현존량이 가장 높은 지역은 문동이었고, 가장 낮은 곳은 서암(2006년)과 동백(2009년)이었다. 출현 해조류를 6개의 기능형으로 구분하면, 성긴분지형이 58.7%와 58.1%, 다육질형이 10.9%와 11.6%, 사상형이 13.0%와 9.3%, 각상형이 6.5%와 9.3%, 엽상형이 6.5%와 7.0%, 유절산호말형이 4.3%와 4.7%로 나타났다. 생태지수인 R/P, C/P, (R+C)/P 값은 2006년에 4.00, 0.75, 4.75와 2009년에 5.17, 1.00, 6.17로 나타났다. 2006년과 2009년의 자료를 분석했을 때, 기장 연안의 해조류 출현 종 수와 현존량은 유사하였다. 이러한 자료로 볼 때, 기장 연안에서 시행된 소규모 공사 전, 후인 2006년과 2009년의 해조류 종 다양성에는 변화가 나타나지 않은 것으로 분석되었다.

• Journal of Microbiology and Biotechnology
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• 제10권6호
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• pp.817-822
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• 2000

A proper flashing light is expected to enhance microalgal biomass productivity and photosynthetic efficiency. The effect of flashing light on high-density Chlorella kessleri (UTEX 398) cultures was studied using light-emitting diodes. A frequency modulator was designed to flash LEDs, and the device successfully provided wide range of frequencies and various duty cycles of flashing. A relatively high frequencies of 10, 20 and 50 kHz were used in this study. These frequencies have very short flashing time ($2-50{\mu}s$), which corresponded to the time constant of the light reaction of photosynthesis. The specific oxygen production rates of photosynthesis under flashing light were compared with those under an equivalent continuous light in specially designed illumination cuvette. The specific oxygen production rates under flashing light were 5-25% higher than those under the continuous light. A range of cell concentration was discovered, where the benefit of flashing light was maximized. The photosynthetic efficiency was also higher under flashing light with frequencies of over 1 kHz, which was a clear indication of flashing light effect and the degree of mutual shading could by overcome by flashing lights, particularly at high-density algal cultures.

• 한국수산과학회지
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• 제40권4호
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• pp.220-225
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• 2007

The succession of marine benthic algae and the restoration of an artificial seaweed forest on a porous type (shaped half saw teeth) artificial reef at Jeju island, Korea was studied. Young thalli of Sargassum horneri and Ecklonia cava were attached to different artificial substrates. In general, the succession on the artificial reefs led from filamentous algae to perennial algae and involved more than 25 species that are useful fishery resources, including E. cava. Coralline algae were dominant on the artificial reefs at the Kangjung site. The maximum algal biomass on the artificial reef in October 2005 was $1,990g/m^2$ at Biyang. In conclusion, a climax community and seaweed forest can be attained one year after the substrate is constructed.

• 한국물환경학회지
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• 제27권4호
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• pp.413-424
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• 2011

The study was aimed to evaluate the applicability of a three-dimensional (3D) hydrodynamic and water quality model, ELCOM-CAEDYM for Yongdam Reservoir, Korea. The model was applied for the simulations of hydrodynamics, thermal stratification processes, stream density flow propagation, and water quality parameters including dissolved oxygen, nutrients, organic materials, and algal biomass (chl-a) for the period of June to December, 2006. The field data observed at four monitoring stations (ST1~ST4) within the reservoir were used to validate the models performance. The model showed reasonable performance nevertheless low frequency boundary forcing data were provided, and well replicated the physical, chemical, and biological processes of the system. Simulated spatial and temporal variations of water temperature, nutrients, and chl-a concentrations were moderately consistent with the field observations. In particular, the model rationally reproduced the succession of different algal species; i.e., diatom dominant during spring and early summer, after then cyanobacteria dominant under warm and stratified conditions. ELCOM-CAEDYM is recommendable as a suitable coupled 3D hydrodynamic and water quality model that can be effectively used for the advanced water quality management of large stratified reservoirs in Korea.

• 환경위생공학
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• 제14권3호
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• pp.123-129
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• 1999

The utilization methods of algae biomass have been studied constantly in whole world. These are $\circled1$the wastewater treatment if waste stabilization pond and oxidation ditch etc. and $\circled2$the biosorption of heavy metals and recovery of strategic' precious metals and $\circled3$the single-celled protein production and the production of chemicals like coloring agent and $\circled4$the production of electric energy through methane gasification. The culture system also has been developed constantly in relation with such utilization method developments. In the result of experimental operation under continuous and cyclic irradiation of light, using high rate algae biomass culture pond(HRABCP), which had been made so as to be an association system with the various items which had been managed to have high efficiency for algae culture, the algae production of the 12 hours-irradiance pond was 41.48 Chlorophyll-a ${\mu}g/L$ only in spite of having the more chance of $CO_2$ synthesis to algae cell than the 24 hours-irradiance pond. This means that the energy supply required for dark-reaction of photosynthesis is very important like this. The difference of algae production between continuous and cyclc irradiation explains that the dark-reaction of photosynthesis acts on algae production as the biggest primary factor. The continuous irradiance on HRABCP made the good algae-production($1403.97{\;}{\mu}g$ Chlorophyll-a/mg) and the good oxygen-production(5.8 mg $O_2/L$) and the good solid-liquid seperation. especially, DO concentration through the oxygen-production was enough to fishes' survival.

• Journal of Microbiology and Biotechnology
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• 제26권3호
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• pp.503-510
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• 2016

The accumulation (internal and superficial distribution) of magnesium ions (Mg²⁺) by the green freshwater microalga Chlorella vulgaris (C. vulgaris) was investigated under autotrophic culture in a stirred photobioreactor. The concentrations of the three forms of Mg²⁺ (dissolved, extracellular, and intracellular) were determined with atomic absorption spectroscopy during the course of C. vulgaris growth. The proportions of adsorbed (extracellular) and absorbed (intracellular) Mg²⁺ were quantified. The concentration of the most important pigment in algal cells, chlorophyll a, increased over time in proportion to the increase in the biomass concentration, indicating a constant chlorophyll/biomass ratio during the linear growth phase. The mean-average rate of Mg²⁺ uptake by C. vulgaris grown in a culture medium starting with 16 mg/l of Mg²⁺ concentration was measured. A clear relationship between the biomass concentration and the proportion of the Mg²⁺ removal from the medium was observed. Of the total Mg²⁺ present in the culture medium, 18% was adsorbed on the cell wall and 51% was absorbed by the biomass by the end of the experiment (765 h). Overall, 69% of the initial Mg²⁺ were found to be removed from the medium. This study supported the kinetic model based on a reversible first-order reaction for Mg²⁺ bioaccumulation in C. vulgaris, which was consistent with the experimental data.

• Environmental Engineering Research
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• 제25권2호
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• pp.135-146
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• 2020

This study was aimed to investigate the possibility of using raw and anaerobically-digested piggery wastewater as culture media for a green microalga Chlorella vulgaris (C. vulgaris). Due to high concentration of ammonia and dark color, the microalga did not grow well in this wastewater. In order to solve this problem, air stripping and NaOCl-treatment were applied to reduce the concentration of NH₃-N and the color intensity from the wastewater. Algal growth was monitored in terms of specific growth rate, biomass productivity, and nutrient removal efficiency. As a result, C. vulgaris grew without any sign of inhibition in air-stripped and 10-folds diluted anaerobically-digested piggery wastewater with enhanced biomass productivity of 0.57 g/L·d and nutrient removal of 98.7-99.8% for NH₃-N and 41.0-62.5% for total phosphorus. However, NaOCl-treatment showed no significant effect on growth of C. vulgaris, although dark color was removed greatly. Interestingly, despite that the soluble organic concentration after air stripping was still high, the biomass productivity was 4.4 times higher than BG-11. Moreover, air stripping was identically effective for raw piggery wastewater as for anaerobic digestate. Therefore, it was concluded that air stripping was a very effective method for culturing microalgae and removing nutrients from raw and anaerobically-digested piggery wastewaters.

• 한국수산과학회지
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• 제44권5호
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• pp.524-532
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• 2011

The intertidal benthic macroalgal floras of 19 uninhabited islands were investigated in the Goheung area, South Sea, Korea, in June 2008. Seaweed community structures on the rocky shores of four (Naemaemuldo, Ceoldo, Araedombaeseom, and Jinjioedo) of the 19 islands were also examined. Eighty macroalgal species were identified, including 13 green, 19 brown, and 48 red algae. The maximum number of species was found at Naemaemuldo, with 35 species, and the minimum was at Aredombaeseom, with 21 species. Seaweed biomass ranged from 21.39-76.22 g dry wt/$m^2$, with a maximum at Naemaemuldo, and minimum at Jinjioedo. Sargassum thunbergii was a representative species, distributed widely in the intertidal zone of the four islands. Subdominant seaweeds were Corallina pilulifera and Ulva pertusa at Naemaemuldo and Jinjioedo, respectively. Also, Ishige okamurae was dominant at Ceoldo and Araedombaeseom. Six functional seaweed forms were found at each study site, except for Araedombaeseom, which had four functional groups. On the rocky shores of the four sites, a coarsely-branched form was the most dominant functional group ranging from 44.44-61.90% in species number and 72.42-91. 09% in biomass. In conclusion, among the four study sites, the shore of Naemaemuldo Island had the best ecological status, with the highest number of species, and greatest biomass (mainly brown and red algae) and functional form diversity of seaweeds. Furthermore, on the rocky shore of Naemaemuldo, coarsely branched- and joint calcareous-form seaweeds, which grow in clean and undisturbed environmental conditions, were the representative functional forms.