• Journal of the Korean Society for Marine Environment & Energy
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• v.6 no.2
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• pp.3-15
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• 2003

Recently more than 450 incidents of oil spill a year have occurred in nearshore of Korea, which caused unmeasurelable losses in fisheries and severe damage in marine ecosystem. Two approaches remain paramount in any response to marine oil spill : the enhancement of natural dispersion of the oil by using dispersants, and mechanical recovery using booms and skimmers. A technique currently receiving fresh attention is the enhancement of the natural bioremediation of oil through the application of micro-organisms and/or nutrient. Oil, like many natural substances, will biodegrade over a period of time into simple compounds such as carbon dioxide, water and biomass. Bioremediation is the term used to describe a range of processes which can be used to accelerate natural biodegradation. More specifically biostimulation is the application of nutrients, and bioaugremetation or seeding is the addition of microbes specially selected to degrade oil. Bioremediation is an economically attractive method for the clean-up of oil-contaminated area. Bioremediation has been demonstrated to be an effective oil spill countermeasure for use in cobble, sand beach, salt marsh, and mud flat environment.

• Design & Manufacturing
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• v.13 no.2
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• pp.30-36
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• 2019

Traditional cell culture(2-dimensional) is the method that provide a nutrient and environment on a flat surface to cultivate cells into a single layer. Since the cell characteristics of 2D culture method is different from the characteristics of the cells cultured in the body, attempts to cultivate the cells in an environment similar to the body environment are actively proceeding in the industry, academy, and research institutes. In this study, we will develop a technology to fabricate micro-structures capable of culturing cells on surfaces with various curvatures, surface shapes, and characteristics. In order to fabricate the hemispheric plastic structure(thickness $50{\mu}m$), plastic preform mold (hereinafter as "preform mold") corresponding to the hemisphere was first prepared by injection molding in order to fabricate a two - layer structure to be combined with a flat plastic film. Then, thermoplastic polymer dissolved in an organic solvent was solidified on a preform mold. As a preliminary study, we proposed injection molding conditions that can minimize X/Y/Z axis deflection value. The effects of the following conditions on the preform mold were analyzed through injection molding CAE, [(1) coolant inlet temperature, (2) injection time, (3) packing pressure, (4) volume-pressure (V/P). As a result, the injection molding process conditions (cooling water inlet temperature, injection time, holding pressure condition (V / P conversion point and holding pressure size)) which can minimize the deformation amount of the preform mold were derived through CAE without applying the experimental design method. Also, the derived injection molding process conditions were applied during actual injection molding and the degree of deformation of the formed preform mold was compared with the analysis results. It is expected that plastic film having various shapes in addition to hemispherical shape using the preform mold produced through this study will be useful for the molding preform molding technology and cast molding technology.

• Korean Journal of Environment and Ecology
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• v.36 no.4
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• pp.422-432
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• 2022

Soil and micro-climatic environmental monitoring was conducted to evaluate the factors causing tree growth impediments at the Baekdudaegan ecological axis restoration project site. As a result, it was found that the nutrient supply was insufficient in the restoration project site due to the lack of organic matter, total nitrogen and cation exchange capacity of the soil compared to the surrounding forest. After the completion of the restoration, the soil moisture in the autumn decreased more than 7 times faster than that of the surrounding forest, and it was evaluated that the soil moisture was significantly low due to the lack of silt and clay content. In the case of the restoration site, the annual potential evapotranspiration was analyzed to be 975mm, which is approximately two times higher than that of the surrounding forest. The soil moisture of the restoration site in the summer decreased rapidly during the daytime when the amount of insolation increased and this was found to be strongly influenced by the increase in potential evapotranspiration. In order to improve the above factors affecting the tree growth at the Baekdudaegan ecological axis restoration project site, it is necessary to induce the smooth supply of nutrients and water to plants by improving physical proprieties and cation exchange capacity, i.e., using litterfall, humus soil, soil conditioner and organic fertilizer. The results of this study are expected to serve as basic data for the design, construction, and management of ecological axis restoration projects in the future.

• Korean Journal of Environmental Biology
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• v.40 no.1
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• pp.54-69
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• 2022

We conducted a field survey from 2018 to 2020 to analyze the spatial distribution of phytoplankton communities at 13 stations in the East Sea. The diatom Chaetoceros curvisetus appeared as the dominant species in winter, and small flagellates less than 20 ㎛ prevailed in all seasons except winter. The seasonal average range of the micro (>20 ㎛), nano (20 ㎛≥Chl-a>3 ㎛), and picophytoplankton (≤3 ㎛) was 20.6-26.2%, 27.1-35.9%, and 40.8-49.0%, respectively. The composition ratio of nano and picophytoplankton was high at the surface mixed layer from spring to autumn when the water columns were strongly stratified. Especially, the stability of the water mass was increased when the summer surface water temperature was higher than that of the previous year. As a result, the nutrient inflow from the lower layer to the surface was reduced as the ocean stratification layer was strengthened. Therefore, the composition ratio of nano and picophytoplankton was the highest at 77.9% at the surface mixed layer. In conclusion, the structure of the phytoplankton community in the East Sea has been miniaturized, which is expected to form a complex microbial food web structure and lower the carbon transfer rate to the upper consumer stage.

• 한국해양학회지
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• v.21 no.1
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• pp.13-24
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• 1986

The daily net primary production by phytoplankton in the southeastern sea of Korea in October 1985 ranged from 0.7 to 2.7 gCm$\^$-2/ d$\^$-1/ and averaged to be 1.3 gCm$\^$-2/ d$\^$-1/. Surface total chlorophyll ranged from 0.97 to 3.59mg chlm$\^$-3/. Primary production by nano-phytoplankton(〈20$\mu\textrm{m}$) ranged from 43 to 97% in the surface layer. Optimum light intensity(Iopt)was around 300 to 700${\mu}$Es$\^$-1/m$\^$-1/. Surface primary production from 9:00 to 15:00 h was evidently inhibited by strong light intensity beyond the Iopt. Phytoplankton near the base of euphotic zone(30-40m) showed extremely low Iopt suggesting adaptation to a low light environment. Since Iopt represents the history of light experience of phytoplankton at a given depth, the extent of variation in I of phytoplankton at different depth seems to be related to the in tensity of turbulence mixing in the surface mixed layer. From the present study, ammonium excretion by macrozooplankton (〉350$\mu\textrm{m}$) contributes from 3 to 19% of daily total nitrogen requirement by phytoplandton in this area. Calculation of upward flux of nitrate to the surface mixed layer from the lower layer, based on the simple diffusion model, approximates 3% of nitrogen requirement by phytoplankton. However, large portion of nitrogen requirement by phytoplankton remains unexplained in this area. In upwelling area near the coast, adjective flux might be the major source for the nitrogen requirement by phytoplankton. This study suggests that the major nitrogen source for the phytoplankton growth might come from the pelagic regeneration by nano-and micro-sized heterotrophic plandkon. Enhancement of primary production during the passage of the warm Tsushima Current is discussed in relation with nutrient dynamics and hydrlgraphic processes in this area.

• Horticultural Science & Technology
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• v.31 no.1
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• pp.65-71
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• 2013

This research was conducted to evaluate the influence of $NO_3{^-}:NH_4{^+}$ ratios in fertilizer solution on the vegetative growth and fruit yield of hot pepper (Capsicum annuum L.) through pot cultivation. The Hoaglad's solution was modified to contain various $NO_3{^-}:NH_4{^+}$ ratios such as 100:0 (A), 73:37 (B), 50:50 (C), 27:73 (D), 0:100 (E), and no nitrogen (F). Plants were transplanted into root substrates and the modified solutions were applied as plant needed in plastic house. There were no statistical significances among the treatments from A through D in the fresh and dry weights, and number of leaves 31 days after transplanting, but elevation of $NH_4{^+}$ ratios in the solution decreased the fresh fruit weight 62 days after transplanting with statistical differences. In the results of inorganic element analysis based on the dry weight of fully expanded mature leaves, N and P contents as well as micro cations such as Fe, Mn, Zn, and Cu increased as $NH_4{^+}$ ratios were elevated 62 days after transplanting. However, those of macro cations such as K, Ca, and Mg resulted in decreasing tendency. The elevation of $NH_4{^+}$ ratios in fertilizer solution resulted in the increase of EC and total N concentrations ($NO_3{^-}+NH_4{^+}$), but this decreased the pH as well as Ca and Mg concentrations in soil solution 62 days after transplanting. The K concentration in soil solution was the highest in the treatments of C and followed by D, B, E, and A. The above results indicate that the proper $NO_3{^-}:NH_4{^+}$ ratio in the nutrient solution is 73:27 (B) or 100:0 (A) and the B solution is proper for the vegetative growth and that of A is proper for reproductive growth stage.

• Journal of Nutrition and Health
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• v.48 no.6
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• pp.476-487
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• 2015

Purpose: This study was conducted to examine the concentration of nutrients in transitional breast milk from Korean lactating mothers and to evaluate daily intakes of their infants based on the Dietary Reference Intakes for Koreans 2010 (KDRIs 2010). Methods: Breast milk samples were collected at 5~15 days postpartum from 100 healthy lactating Korean mothers. Macro- and micro-nutrients, and immunoglobulin (Igs) concentrations in breast milk were analyzed. Results: The mean energy, protein, fat, and carbohydrate concentrations in breast milk were $59.99{\pm}8.01kcal/dL$, $1.47{\pm}0.27g/dL$, $2.88{\pm}0.89g/dL$, and $6.72{\pm}0.22g/dL$. The mean linoleic acid (LA), a-linolenic acid (ALA), arachidonic acid (AA), and docosahexaenoic acid (DHA) concentrations were $181.44{\pm}96.41mg/dL$, $28.15{\pm}8.89mg/dL$, $5.67{\pm}1.86mg/dL$, and $5.74{\pm}2.57mg/dL$. The mean vitamin A, vitamin D, vitamin E, vitamin $B_1$, vitamin $B_2$, vitamin $B_{12}$, and folate concentrations were $2.75{\pm}1.75{\mu}g/dL$, $2.31{\pm}1.12ng/dL$, $0.74{\pm}1.54mg/dL$, $3.02{\pm}1.84mg/dL$, $7.51{\pm}20.96{\mu}g/dL$, $61.78{\pm}26.78{\mu}g/dL$, $63.71{\pm}27.19ng/dL$, and $0.52{\pm}0.26{\mu}g/dL$. The mean concentrations of calcium, iron, potassium, sodium, zinc, and copper were $20.71{\pm}3.34mg/dL$, $0.59{\pm}0.86mg/dL$, $66.71{\pm}10.35mg/dL$, $27.72{\pm}10.16mg/dL$, $0.44{\pm}0.41mg/dL$, and $70.48{\pm}30.41{\mu}g/dL$. The mean IgA and total IgE concentrations were $61.85{\pm}31.97mg/dL$ and $235.00{\pm}93.00IU/dL$. The estimated daily intakes of infants for protein, vitamin D, vitamin E, vitamin $B_2$, vitamin $B_{12}$, iron, potassium, sodium, zinc, and copper were sufficient compared to KDRIs 2010 adjusted by transitory milk intakes. The estimated infants' intakes of energy, fat, carbohydrate, vitamin A, vitamin C, vitamin $B_1$, folate, and calcium did not meet KDRIs 2010 adjusted by transitory milk intakes. Conclusion: In general most estimated nutrient intakes of Korean breast-fed infants in transitory breast milk were sufficient, however some nutrient intakes were not sufficient based on KDRIs 2010. These results warrant conduct of future studies for investigation of important dietary factors associated with nutrients in breast milk to improve the quality of breast milk, which may contribute to understanding nutrition in early life and promoting growth and development of breast-fed infants.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.6
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• pp.513-521
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• 2009

The primary goal of this research was to develop an optimized analytical procedure for soil analysis based on ion-selective microelectrodes for agricultural purposes, which can perform on-site measurement of various ions in soil easily and rapidly. For the simple and rapid on-site diagnosis, an analysis of soil chemicals was performed employing a multicomponent-in-situ-extractant and an evaluation of ionselective microelectrodes were conducted through the regressive correlation method with a standard analytical approach widely employed in this area. Examination of sensor responses between various soil nutrient extractants revealed that 0.01M HCl and 1M LiCl provided the most ideal Nernstian response. However, 1M LiCl deteriorated the selective response for analytes due to high concentration (1M) of lithium cation. Thus, employing either 0.1M HCl as an extractant followed by 10 times dilution, or 0.01M HCl as an extractant without further dilution was chosen as the optimal extractant composition. A study of regressive correlation between results from ion-selective microelectrodes and those from the standard analytical procedure showed that analyses of $K^+$, $Na^+$, $Ca^{2+}$, and $NO_3{^-}$ showed the excellent consistency between two methods. However, the response for $NH_4{^+}$ suffered the severe interference from $K^+$. In addition, the selectivity for $Mg^{2+}$ over $Ca^{2+}$ was not sufficient enough since available ionophores developed so far do not provide such a high selectivity for $Mg^{2+}$. Therefore, as an agricultural on-site diagnostic instrument, the device in development requires further research on $NH_4{^+}$ analysis in the soil sample, development of $Mg^{2+}$-selective ionophore, and more detailed study focused on potassium, one of the most important plant nutrients.

• The Korean Journal of Malacology
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• v.32 no.3
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• pp.231-240
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• 2016

Techniques were developed for holding and conditioning of Pacific oysters, Crassostrea gigas, in a closed recirculating system. Experimental adults were used 500 oysters ( x two system, total 1,000 oysters) which were collected in $20^{th}$ March 2016 from long-line aquaculture farm at the south coast of Korea. During conditioning periods concentrated live microalgae as Isochrysis sp. $15{\times}10^7cells/mL$, Tetraselmis sp. $2{\times}10^7cells/mL$ and Pheaodactylum sp. $18{\times}10^7cells/mL$ were added 5 L every day, respectively which micro algae were functioned as diets and biological filter. Over all experimental periods total water exchange rate was 21.3% (daily 0.5%). Over 42 days conditioning, female and male oysters were maturated 90.9% and 94.4%, respectively. Survival rate was 98.7%. Mean shell hight (8.3 mm), total wet weight (19.2 g), meat wet weight (5.0 g) and shell wet weight (13.6 g) were significantly increased (P < 0.05). Water quality parameters including the water temperature ($22.1{\pm}0.4^{\circ}C$), salinity ($24.9{\pm}04$), dissolved oxygen (5.1-7.9 mg/L) and pH ($7.93{\pm}0.15$) were kept stable. Concentration of dissolved inorganic nutrient as ammonia (1.96-0.35 mg/L), nitrite (0.03-0.16 mg/L), nitrate (1.34-0.47 mg/L), DIP (0.42-0.03 mg/L) and silicate (3.83-0.00 mg/L) were significantly decreased throughout experiment except nitrite which was increased (P < 0.05), but nitrogenous components stayed below toxic levels (ammonia 0.0-5.5 mg/L, nitrite 0.0-460.0 mg/L) which indicated that closed recirculation system with microalgae based bio-filter could supply sufficiently environment condition to holding and conditioning of oyster.

• Horticultural Science & Technology
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• v.34 no.2
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• pp.220-227
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• 2016

The objective of this research was to investigate the influence of application rates of dolomitic lime in the acid substrate on the mitigation of high bicarbonate damage in 'Seolhyang' strawberry. For this purpose, an acid substrate was formulated by mixing of sphagnum peat moss and pine bark with the ratio of 5:5 (v/v). The pH, EC and CEC of the substrate analyzed before application of dolomite were 4.07, $0.46dS{\cdot}m^{-1}$, and $91.3cmol+/kg^{-1}$, respectively. To adjust the pH of substrate, various amounts of dolomitic lime [$CaMg(CO_3)_2$] such as 0 (control), 1, 2, 3, and $4g{\cdot}L^{-1}$ were added during substrate formulation. Then, seedlings with 3 leaf stage were transplanted as mother plants and those were fed with Hoagland solution containing $240mg{\cdot}L^{-1}$ of the $HCO_3{^-}$. The growth parameters of mother plants 140 days after transplanting, such as plant height, chlorophyll content, and fresh weight were the highest in the treatments of 2 and $3g{\cdot}L^{-1}$ of dolomitic lime. The physiological disorders in mother plants were not observed in the 1, 2 and $3g{\cdot}L^{-1}$ treatments, but the symptoms of Ca, K and B deficiencies were observed in the 0 and $4g{\cdot}L^{-1}$ treatments. During the propagation period, the number of daughter plants derived from each mother plant were 21.0, 29.5, 35.8, 27.3 and 16.0 in the treatments of 0, 1, 2, 3 and $4g{\cdot}L^{-1}$, respectively. The substrate pH during cultivation of mother plants were maintained at appropriate levels for the 1 and $2g{\cdot}L^{-1}$ treatments, whereas it was the highest in $4g{\cdot}L^{-1}$ treatment. The contents of macro- and micro-elements in the above ground tissue were the highest in $2g{\cdot}L^{-1}$ and the lowest in $4g{\cdot}L^{-1}$ lime treatments. Above results suggest that the bicarbonate injury originated from ground water can be mitigated by adjusting the amount of dolomitic lime incorporated into the acid substrate.