• Journal of Environmental Impact Assessment
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• v.20 no.6
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• pp.815-821
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• 2011

This study aims to estimate the biological decomposition capacity of MPC(Microorganism Porous-Concrete). MPC has specific surface area formed by inside pores, and bio compound was added to those pores to reduce pollutants loading. To evaluate the water purification capacity of MPC, we carried out the comparative studies using different media types [GPC(General Porous-concrete), CPC(Compound porous-concrete), LPC(Lightweight aggregate porous-concrete)] under the condition of CFSTR, and different retention times (30, 60 and 120 min). We also estimated the purification capacity of MPC under different concentrations of pollutant loadings. The MPC showed higher efficiency in water purification function than other conventional porous concretes with efficient decrease rates of SS, BOD, COD, and nutrient concentrations. In the comparison experiment for different retention times, MPC showed the highest removal efficiency for all tested pollutants in the longest retention time(120 min). In the long period test, the removal efficiencies of MPC concrete were high until 100 days after the set up of the operation, but began to decrease. Outflow flux was invariable compared with inflow flux so that extra detention time for media fouling such as back washing is not needed. But the results suggested that appropriate management is necessary for long-term operation of MPC. As the final outcome, MPC using bio organisms is considered to be efficient for stream water purification when they used as substrates for artificial river structure.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.45 no.4
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• pp.223-233
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• 2009

It has been considered that fishing areas for shrimp beam trawl have been in ruin because Korean local governments have permitted trawling into the areas limited by the fisheries local regulations from 1994. Physical and biological effects of the trawling were investigated in the study. Physical effects were investigated by optical methods such as trawling tracking by side scan sonar and comparing the gear both before and after trawling. Biological aspects were investigated by grab sampling of benthic animals, concentration of trace metals in sediment and a flux evaluation of ${NH_4}^+,\;{PO_4}^-,\;and\;SiO_2$ by coring. The fishing activity had physical impacts on the seabed but these recovered naturally in less than fourty days naturally, which increased the benthic biodiversity, increases the trace metal concentration of and nutrient flux into the seawater, especially phosphate and silicate. This method and these results can help in further studies looking for disturbances by fishing.

• 한국해양학회지
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• v.27 no.2
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• pp.91-100
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• 1992

For the study on the structure and characteristics of the primary production system in the southern waters of the East Sea, chlorophyll, phytoplankton standing stocks. nutrients and hydrographic properties were investigated and analyzed in conjunction with measurement of C-14 based primary productivity. The primary productivity was relatively high in comparison with the previous studies, ranging from 284 to 4,574 mgC$.$m/SUP -2/$.$day /SUP -1/ and averaged to be 2,000 mgC$.$m/SUP 02/$.$day/SUP -1/. The standing stocks within the euphotic zone were fairly high, but ambient inorganic nitrogenous nutrient concentrations were too low to support the high production. This implied that there might be active recycling of nitrogenous nutrients by heterotrophic processes and the upward flux of nutrients by vertical mixing. Subsurface chlorophyll maxima were continuously observed in the lower parts of the euphotic layer and the depth coincided with the nutricline rather than isopycnal surfaces, supporting the view that chlorophyll distributions and primary production were primarily influenced by nutrient supply. Despite low nutrient concentrations, phytoplankton standing stocks and production were fairly high and the fraction of autotrophic nano- and picoplankton production was significant.

• 한국해양학회지
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• v.24 no.1
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• pp.52-61
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• 1989

The daily net primary production by phytoplankton and ammonium excretion by macrozooplankton (> $350{\mu}m$) were measured to understand the nitrogenous nutrient dynamics in the southern part of the East Sea of Korea. At most of the staions, water columns were well stratified and strongly developed pycnoclines and matching nutriclines could be found near the 20-60m. Total chlorophyll ranged between $1.22-3.24{\mu}g$ ChI/l and nano-fractions of chlorophyll ranged from 43.2 to 99.6% in the surface layer. The daily net primary production by phytoplankton ranged from 0.75 to 2.04 gC/$m^2$/d and averaged to be 1.5 gC/$m^2$/d. 1t is evidenced that the primary production and chlorophyll content are relatively high in frontal waters where the North Korean Cold Water meets with the East Korean Warm Water. The turnover time of nitrate in the euphotic zone ranged from 0.2 day to 1.6 day and averaged to be 0.8 day. The N:P ratio of the study area shows on the average 13.4 which indicates nitrogenous nutrient to be the limiting factor for phytoplankton growth. Ammonium excretion by macrowoplankton averaged out to 1.3mg at-N/$m^2$/d, and contributed 7.3% of daily total nitrogen requirement by phytoplankton in this area. Calculation of upward flux of nitrate to the surface mixed layer from the lower layer approximates 7% of nitrogen requirement by phytoplankton.

• Horticultural Science & Technology
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• v.34 no.3
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• pp.405-413
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• 2016

Quinoa (Chenopodium quinoa Willd.) is a plant native to the Andean region that has become increasing popular as a food source due to its high nutritional content. This study determined the optimal photoperiod, light intensity, and electrical conductivity (EC) of the nutrient solution for growth and yield of quinoa in a closed-type plant factory system. The photoperiod effects were first analyzed in a growth chamber using three different light cycles, 8/16, 14/10, and 16/8 hours (day/night). Further studies, performed in a closed-type plant factory system, evaluated nutrient solutions with EC (salinity) levels of 1.0, 2.0 or $3.0dS{\cdot}m^{-1}$. These experiments were assayed with two light intensities (120 and $143{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) under a 12/12 and 14/10 hours (day/night) photoperiod. The plants grown under the 16/8 hours photoperiod did not flower, suggesting that a long-day photoperiod delays flowering and that quinoa is a short-day plant. Under a 12/12 h photoperiod, the best shoot yield (both fresh and dry weights) was observed at an EC of $2.0dS{\cdot}m^{-1}$ and a photosynthetic photon flux density (PPFD) of $120{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. With a 14/10 h photoperiod, the shoot yield (both fresh and dry weights), plant height, leaf area, and light use efficiency were higher when grown with an EC of $2.0dS{\cdot}m^{-1}$ and a PPFD of $143{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Overall, the optimal conditions for producing quinoa as a leafy vegetable, in a closed-type plant factory system, were a 16/8 h (day/night) photoperiod with an EC of $2.0dS{\cdot}m^{-1}$ and a PPFD of $143{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$.

• Journal of Korean Society on Water Environment
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• v.27 no.3
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• pp.322-328
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• 2011

This study was performed to investigate the characteristics of nutrient removal of municipal wastewater in the membrane bioreactor system with the different types of membrane. Membrane bioreactor consists of three reactors such as two intermittent anaerobic and the submerged membrane aerobic reactor with flat sheet and hollow fiber membrane, respectively. The removal efficiencies of $COD_{cr}$, BOD, SS, TN and TP on the flat sheet membrane bioreactor were 94.3%, 99.0%, 99.9%, 70.3% and 63.1%, respectively. In addition, The removal efficiencies of $COD_{cr}$, BOD, SS, TN and TP on the hollow fiber membrane bioreactor were 94.0%, 99.3%, 99.9%, 69.9% and 66.9%, respectively. The estimated true biomass yield, specific denitrification rate (SDNR), specific nitrification rate (SNR) and phosphorus removal content on the flat sheet membrane bioreactor were $0.33kgVSS/kgBOD{\cdot}d$, $0.043mgNO_3-N/mgVSS{\cdot}d$, $0.031mgNH_4-N/mgVSS{\cdot}d$, and 0.144 kgP/d, respectively. In addition, the estimated true biomass yield, specific denitrification rate (SDNR), specific nitrification rate (SNR) and phosphorus removal content on the hollow fiber membrane bioreactor were $0.30kgVSS/kgBOD{\cdot}d$, $0.067mgNO_3-N/mgVSS{\cdot}d$, $0.028mgNH_4-N/mgVSS{\cdot}d$, and 0.121 kgP/d, respectively. There was little difference between the flat sheet and hollow fiber on the nutrient removal efficiencies except SNR and SDNR. These differences between them were caused by the air demand to prevent the membrane fouling. The flux and oxygen demand for air scouring were $19.0L/m^2/hr$ and $2.28m^3/min$ for the flat sheet membrane, and $20.7L/m^2/hr$ and $1.77m^3/min$ for the hollow fiber membrane on an average.

• Ocean and Polar Research
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• v.23 no.4
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• pp.401-410
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• 2001

Global climate change will alter many such properties of the Southern Ocean as temperature, circulation, stratification, and sea-ice extent. Such changes are likely to influence the species composition and activity of Antarctic marine microorganisms (protists and bacteria) which playa major role in deter-mining the concentration of atmospheric $CO_2$ and producing precursors of cloud condensation nuclei. Direct impacts of climate change on Antarctic marine microorganisms have been determined for very few species. Increasing water temperature would be expected to result in a southward spread of pelagic cyanobacteria, coccolithophorids and others. Growth rates of many species would be expected to increase slightly but nutrient limitation, especially micronutrients, is likely to result in a negligible increase in biomass. The extent of habitats would be reduced for those organisms presently living close to the upper limit of their thermal tolerance. Increased UVB irradiance is likely to favour the growth of those organisms tolerant of UVB and may change the trophic structure of marine communities. Indirect effects, especially those as a consequence of a diminution of the amount of sea-ice and increased upper ocean stratification, are predicted to lead to a change in species composition and impacts on both trophodynamics and vertical carbon flux.

• Korean Journal of Ecology and Environment
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• v.34 no.4 s.96
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• pp.298-309
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• 2001

The purpose of this study was to evaluate the filtering-feeding effect of a freshwater mussel (Corbicula leana) on the phytoplankton communities in two lakes with different trophic conditions between June and September, 2000. Manipulation experiments were conducted with two treatments (the control and mussel addition), and each established in duplicate 10 l chambers. Both ambient nutrient (TN, TP) and chlorophyll-a concentrations were significantly (p<0.01) higher in Lake Ilgam than Lake Soyang. Cyanophytes (Microcystis, Oscillatoria, Lyngbya and Dactylococcopis) consistently dominated algal community in Lake llgam, while flagellated algae (Dinobryon divergence, Mallomonas, Rhodomonas) and cyanophytes (Microcystis)dominated in Lake Soyang. The net exponential death rate ($R\;=\;day^{-1}$) of total phytoplankton in the mussel treatment ranged $1.70{\sim}7.39$ and $0.38{\sim}1.64$ in Lakes Soyang and Ilgam, respectively. Mean filtering rate standardized by mussel AFDW ($ml\;mgAFDW^{1}\;h^{-1}$) was much higher in Lake Soyang ($1.70{\sim}3.06$) than in Lake Ilgam($0.24{\sim}0.88$0.24~o.88). Estimating FR per mussel, 1 mussel filtered $1.6{\sim}7.8\;l$ per day and $1.7{\sim}3.0\;l$ per day in Lakes Soyang and Ilgam, respectively. Based on tile C-flux tobiomass ratio, Corbicula leana consumed $0.8{\sim}4.4$ fold of phytoplankton standing stock in Lake Soyang, and $0.4{\sim}1.6$ fold in Lake Ilgam per day. Mussel feeding resulted in increase of SRP concentration by $30{\sim}50%$, compared with the control. The results of this study suggest that filter-feeding activity of Corbicula leana varies depending on the phytoplankton density and community composition. The high seston consumption rate of Corsicuja Jeaua even in a eutrophic lake suggests that biomanipulation approach using filter-feeding mussels can be used far wate rquality management in small eutrophic reservoirs.

• Journal of Bio-Environment Control
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• v.27 no.4
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• pp.371-380
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• 2018

Aim of this study was to investigate the effects of different nutrient solutions and various light qualities generated by LED on the growth and glucosinolates contents of watercress (Nasturtium officinale) grown under hydroponics for 3 weeks. The seeds of watercress were sown on crushed rockwool media and raised them for two weeks. They were transplanted in a semi-DFT (deep flow technique) hydroponics system. A controlled-environment room was maintained at $20{\pm}1^{\circ}C$ and $16{\pm}1^{\circ}C$ temperatures and $65{\pm}10%$ and $75{\pm}10%$ relative humidity (day and night, respectively), with a provided photosynthetic photon flux density (PPFD) of $180{\pm}10{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ and a photoperiod of 16/8h. To find out the best kinds of nutrient solutions for growing watercress, Otsuka House 1A (OTS), Horticultural Experiment Station in Korea (HES), and Netherland's Proefstaion voor Bloemisterij en Gasgroente (PBG) were adapted with initial EC of $1.0-1.3dS{\cdot}m^{-1}$ and pH of 6.2, irradiating PPFD with fluorescent lamps (Ex-1). Either monochromatic (W10 and R10) or mixed LEDs (R5B1, R3B1, R2B1G1, and W2B1G1) were irradiated with a differing ratio of each LED's PPFD to understanding light quality on the growth and glucosinolates contents of watercress (Ex-2). Although significant difference in the shoot growth of watercress was not found among three nutrient solutions treatments, but the root fresh weight increased by 13.7% and 55.1% in PBG and OTS compared to HES, respectively. OTS increased the gluconasturtiin content by 96% and 65% compared to PBG and HES. Compared with the white light (W10), the red light (R10) showed a 101.3% increase in the shoot length of watercress. Increasing blue light portion positively affected plant growth. The content of total glucosinolates in watercress was increased by 144.5% and 70% per unit dry weight in R3B1 treatment compared with R2B1G1 and W10 treatments, respectively. The growth and total glucosinolates contents of the watercress were highest under R3B1 among six light qualities.

• Journal of Bio-Environment Control
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• v.8 no.1
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• pp.49-55
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• 1999

This study aims at analyzing environment factors of two tier cropping systems and suggesting effective structures of two tier cropping systems. The environment factors in two tier cropping systems are temperature, relative humidity, solar radiation, temperature of nutrient solution, and wind velocity. Especially, The most important factors are the solar radiation and the solar incident area between the two tiers. During the experiment, observations were made of the two levels in the plastic greenhouse. The highest temperatures were 38.3$^{\circ}C$ in the top level and, 35.5$^{\circ}C$ in the bottom level, respectively. The temperature of the nutrient solution between the two levels showed little difference. The relative humidity in the top level was 60~7o% and that in the bottom 65~80%, exhibiting that the bottom is approximately 10% higher. Change of photosynthetic photon flux density and solar radiation both have a tendency to be similar. The wind velocities for both levels were recorded at 0.1m.s$^{-1}$ in the afternoon and 0.05m.s$^{-1}$ in the evening. The solar incident areas in the bottom level increased by approximately 25% at an East-West position and 17.7% at a South-North position, respectively.