• Korean Journal of Ecology and Environment
• /
• v.37 no.4 s.109
• /
• pp.436-447
• /
• 2004

Wetland plants have evolved specialized adaptations to survive in the low-oxygen conditions associated with prolonged flooding. The development of internal gas space by means of aerenchyma is crucial for wetland plants to transport $O_2$ from the atmosphere into the roots and rhizome. The formation of tissue with high porosity depends on the species and environmental condition, which can control the depth of root penetration and the duration of root tolerance in the flooded sediments. The oxygen in the internal gas space of plants can be delivered from the atmosphere to the root and rhizome by both passive molecular diffusion and convective throughflow. The release of $O_2$ from the roots supplies oxygen demand for root respiration, microbial respiration, and chemical oxidation processes and stimulates aerobic decomposition of organic matter. Another essential mechanism of wetland plants is downward water movement across the root zone induced by water uptake. Natural and constructed wetlands sediments have low hydraulic conductivity due to the relatively fine particle sizes in the litter layer and, therefore, negligible water movement. Under such condition, the water uptake by wetland plants creates a water potential difference in the rhizosphere which acts as a driving force to draw water and dissolved solutes into the sediments. A large number of anatomical, morphological and physiological studies have been conducted to investigate the specialized adaptations of wetland plants that enable them to tolerate water saturated environment and to support their biochemical activities. Despite this, there is little knowledge regarding how the combined effects of wetland plants influence the biogeochemistry of wetland sediments. A further investigation of how the Presence of plants and their growth cycle affects the biogeochemistry of sediments will be of particular importance to understand the role of wetland in the ecological environment.

• Korean Journal of Food Science and Technology
• /
• v.32 no.1
• /
• pp.25-30
• /
• 2000

Phytoestrogen has been used as a suppliment of estrogen in order to treat osteoporosis. The representative phytoestrogens, isoflavones, are daidzein, genistein and formononetin which were present highly in our traditional soybean foods. The quantitative analysis of the isoflavone was done with a high performance liquid chromatography(HPLC) using a UV/VIS detector for the contents of the isoflavones in Astragali Radix, soybean sprouts, bean-curd(Tofu), soybean, soybean oil, pea, kidney pea, black bean(Yak-kong), soybean sauce(Ganjang). soybean paste(Doenjang), and fermented soybean(Maejoo). The content of free daidzein in soybean sprouts was $43.49{\pm}3.41\;mg/kg$$ which was much higher than that in soybean, $14.52{\pm}0.58\;mg/kg$, although total daidzein of fermented soybean was lower than that in soybean (Table 2. P<0.01). The amounts of free genistein in soybean sprouts, fermented soybean. and soybean paste were $27.63{\pm}1.66\;mg/kg,\;291.52{\pm}6.81\;mg/kg,\;and\;18.75{\pm}1.33\;mg/kg$, respectively. The level of free formononetin in soybean paste was the highest among the soybean products (P<0.01). The content of formononetin in Aatragali Radix, $9629.73{\pm}0.57\;{\mu}g/kg$, was about 160 times higher than that in soybean. Thus Korean traditional soybean products, black bean(Yak-Kong) and Astragali Radix can be a good choice of phytoestrogens.

• Applied Biological Chemistry
• /
• v.47 no.1
• /
• pp.27-32
• /
• 2004

The antagonistic microorganisms against Salmonella gallinarum causing fowl typhoid were isolated from the gut of wild pheasant. The isolated L19, L33, L50 strains were showed the characteristics of isolated Gram negative, rods, catalase positive and oxidase negative. Finally, all strains were identified as Sphingomonas sanguis by $Biolog^{\circledR}$ system. The optimal carbon sources of Sphingomonas sanguis L19, L33 and L50 for the these growth ~ere glucose, saccharose, and fructose respectively. But the optimal carbon sources of S. sanguis L19,L33, L50 for the antagonistic material production were maltose, galactose, and saccharose respectively. The optimal nitrogen sources of S. sanguis L19, L33, L50 for the growth were yeast extract, yeast extract, and $NH_4H_2PO_4$ respectively. But the optimal nitrogen sources of S. sanguis L19, L33 and L50 for the antagonistic material production were $(NH_4)_2SO_4$ urea, $(NH_4)_2S_2O_8$ espectively.

• Transactions of the Korean hydrogen and new energy society
• /
• v.28 no.2
• /
• pp.156-165
• /
• 2017

This study quantitatively assessed the environmental impacts of fuel cell (FC) systems by performing life cycle assessment (LCA) and analyzed their energy efficiencies based on energy return on investment (EROI) and electrical energy stored on investment (ESOI). Molten carbonate fuel cell (MCFC) system and polymer electrolyte membrane fuel cell (PEMFC) system were selected as the fuel cell systems. Five different paths to produce hydrogen ($H_2$) as fuel such as natural gas steam reforming (NGSR), centralized naptha SR (NSR(C)), NSR station (NSR(S)), liquified petroleum gas SR (LPGSR), water electrolysis (WE) were each applied to the FCs. The environmental impacts and the energy efficiencies of the FCs were compared with rechargeable batteries such as $LiFePO_4$ (LFP) and Nickel-metal hydride (Ni-MH). The LCA results show that MCFC_NSR(C) and PEMFC_NSR(C) have the lowest global warming potential (GWP) with 6.23E-02 kg $CO_2$ eq./MJ electricity and 6.84E-02 kg $CO_2$ eq./MJ electricity, respectively. For the impact category of abiotic resource depletion potential (ADP), MCFC_NGSR(S) and PEMFC_NGSR(S) show the lowest impacts of 7.42E-01 g Sb eq./MJ electricity and 7.19E-01 g Sb eq./MJ electricity, respectively. And, the energy efficiencies of the FCs are higher than those of the rechargeable batteries except for the case of hydrogen produced by WE.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.19 no.4
• /
• pp.347-355
• /
• 1986

The Sonakdong river is very important water source not only for agricultural water of Kimhae field but also for fishery water. Recently the middle and lower areas of the river have the tendency to be heavily contaminated by domestic sewage and agricultural chemicals. Fifty six water samples were collected from 8 stations from July to December in 1985 for the experiment (Fig. 1). To evaluate the water quality, pH, water temperature, electrical conductivity, chloride ion, nutrients ($NO^{-}_{2}-N,\;NO^{-}_{3}-N,\;NH^{+}_{4}-N,\;PO^{3-}_{4}-P,\;SiO_2-Si$), total coliform, fecal coliform, and fecal streptococcus were determined. Range and mean value of the samples were as follows; pH $6.3{\sim}9.4$, 7.91; water temperature $6.1{\sim}34.8^{\circ}C,\;23.88^{\circ}C$; electrical conductivity (from St. A to G) $1.575{\times}10^2{\sim}30.50{\times}10^2{\mu}{\mho}/cm,\;6.57{\times}10^2{\mu}{\mho}/cm$; chloride ion $23.5{\sim}14,300mg/l$, 770.0mg/l; nitrite-nitrogen $0.007{\sim}0.110mg/l$, 0.053mg/l; nitrate-nitrogen $0.001{\sim}1.638mg/l$, 0.649 mg/l; ammonia-nitrogen $0.017{\sim}4.200mg/l$, 0.497mg/l; phosphate-phoshorus $0.011{\sim}0.281mg/l$, 0.086mg/l; and silicate-silicious $2.4{\sim}6.5mg/l$, 4.43mg/l. Electrical conductivity and chloride ion of the station F(Chomanpo) were $2.676{\times}10^2{\mu}{\Omega}cm$ and 123.99mg/l which were lower than those of others. Among the analyzed nutrients, silicate-silicious concentration was the highest through all the samples. The bacterial density of the samples ranged $36{\sim}110,000/100ml$ for total coliform, $15{\sim}46,000/100ml$ for fecal coliform and $3.6{\sim}15,000/100ml$ for fecal streptococcus. The range and the mean of the TC/FC ratio were $3.0{\sim}9.6$, 5.51 and those of the FC/FS ratio were $1.1{\sim}9.2$, 6.19, respectively. On the other hand, fecal coliform was not detected in about $78\%$ of the water samples examined. Composition of coliform was $52\%$ Escherichia coli group, $3\%$ Citrobacter freundii group, $13\%$ Enterobacter aerogenes group and $31\%$ others.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.6
• /
• pp.794-801
• /
• 2013

This paper reports the production and characterization of crude xylanase from the newly isolated Humicola sp. Ly01. The highest (41.8 U/ml) production of the crude xylanase was obtained under the optimized conditions (w/v): 0.5% wheat bran, 0.2% $KH_2PO_4$, and 0.5% peptone; initial pH 7.0; incubation time 72 h; $30^{\circ}C$; and 150 rpm. A considerable amount of the crude xylanase was induced using hulless barley bran or soybean meal as the carbon source, but a small amount of the enzyme was produced when supplementary urea was used as the nitrogen source to wheat bran. The crude xylanase showed apparent optimal cellulase-free xylanase activity at $60^{\circ}C$ and pH 6.0, more than 71.8% of the maximum xylanase activity in 3.0-30.0% (v/v) ethanol and more than 82.3% of the initial xylanase activity after incubation in 3.0-30.0% (v/v) ethanol at $30^{\circ}C$ for 2 h. The crude xylanase was moderately resistant to both acid and neutral protease digestion, and released 7.9 and 10.9 ${\mu}mol/ml$ reducing sugar from xylan in the simulated gastric and intestinal fluids, respectively. The xylooligosaccharides were the main products of the hydrolysis of xylan by the crude xylanase. These properties suggested the potential of the crude enzyme for being applied in the animal feed industry, xylooligosaccharides production, and high-alcohol conditions such as ethanol production and brewing.

• Journal of Korean Society of Forest Science
• /
• v.97 no.3
• /
• pp.285-290
• /
• 2008

This study was carried out to obtain an optimal liquid culture condition for Sarcodon aspratus mycelia. Among various basal culture media the GYS (glucoe-yeast extract-soytone) medium was the best for mycelial growth. The appropriate temperature was $25^{\circ}C$. Starch, maltose or glucose was excellent carbon sources for the mycelial culture, compared to others tested. As nitrogen nutrients, soytone and $NH_4-N$ were the best organic and inorganic nitrogen sources, respectively. Moreover, the optimal concentration of soytone was 3 g per one-liter medium. In addition, we also found that alanine, $(NH_4)H_2PO_4$, and nicotinic acid were the best aminoacid, phosphorus salt, and vitamin, respectively. When all optimal conditions described above were applied to culture medium, we were able to produce 5.7 g dry weight of S. aspratus mycelia per one-liter liquid medium within 20 days.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.515-515
• /
• 2023

팔당호는 북한강과 남한강이 합류하여 생성된 호소로 수도인 서울과 수도권인 경기도 동부지역의 물 공급을 담당하는 중요한 상수원이다. 이러한 팔당호에서 유해남조 발생은 상수원수 활용과 직접적으로 연관되어 있어 신속하고 정확한 관리 및 예측이 필요하다. 본 연구에서는 안전한 상수원 활용을 위해, 딥러닝 기법을 이용하여 유해남조 사전 예측 모델을 구축하고자 하였다. 모델 입력 변수는 2012년부터 2021년까지 10년 동안의 주간 팔당호 수질(수온, DO, BOD, COD, Chl-a, TN, TP, pH, 전기전도도, TDN, NH4N, NO3N, TDP, PO4P, 부유물질)과 수문(유입량, 총방류량), 기상 정보(평균기온, 최저기온, 최고기온, 일 강수량, 평균풍속, 평균 상대습도, 합계일조량), 그리고 북한강과 남한강 유입지점의 남조 세포 수를 사용하였다. 모델 출력 변수는 수질, 수문, 기상 요인으로 인한 남조의 성장 발현 시기를 고려하여 1주 후의 댐앞 남조 세포수를 사용하였다. 사용한 딥러닝 기법은 최근 주목받고 있는 Temporal Fusion Transformer (TFT)를 사용하였다. 모델 훈련용 데이터와 테스트용 데이터는 각각 8:2의 비율로 나누었으며, 검증용 데이터는 훈련용 데이터 내에서 훈련 데이터와 검증 데이터를 6:4 비율로 분배하였다. Lookback은 5로 설정하였고, 이는 주단위 데이터로 구성된 데이터세트의 특성을 반영한 것이다. 모델의 성능은 실측값과 예측값을 토대로 R-square와 Root Mean Squared Error (RMSE)를 계산하여 평가하였다. 모델학습은 총 154번 반복 진행되었으며, 이 중 성능이 가장 준수한 시점은 54번째 반복 시점으로 훈련손실 대비 검증손실이 가장 양호한 값을 나타냈다(훈련손실:0.443, 검증손실 0.380). R-square는 훈련단계에서 0.681, 검증단계에서 0.654였고, 테스트 단계에서 0.606으로 산출되었다. RMSE는 훈련단계에서 0.614(㎍/L), 검증단계에서 0.617(㎍/L), 테스트 단계에서 0.773(㎍/L)였다. 모델에 사용한 데이터세트가 주간 데이터라는 특성을 고려하면, 소규모 데이터를 사용하였음에도 본 연구에서 구축한 모델의 성능은 양호하다고 평가할 수 있다. 향후 연구에서 데이터세트를 보강하고 모델을 업데이트한다면, 모델의 성능을 더욱더 개선할 수 있을 것으로 기대된다.

• Applied Biological Chemistry
• /
• v.44 no.3
• /
• pp.185-190
• /
• 2001

Alginate, a well-known biopolymer, is universally applied for immobilization of microbial cells. Biosorption characteristics of lead by waste biomass of immobilized A. niger beads, used in fermentation industries to produce citric acid, were studied. The immobilized A. niger beads, prepared via capillary extrusion method using calcium chloride, were applied in the removal of lead. Pb uptake was the highest in A. niger beads cells grown for 3 days with medium producing citric acid (12% sucrose, 0.5% $NH_4NO_3$, 0.1% $KH_2PO_4$, and 0.025% $MgSO_4$). Lead uptake by the immobilized A. niger beads and free A. niger mycellia beads increased sharply with time. However, while uptake by the immobilized A. niger beads continued to increase slowly, that by free A. niger mycellia beads stopped after 30 min. The optimum pH and temperature of lead uptake were found to be 6 and $35^{\circ}C$, respectively. The maximum uptake of lead was achieved with $50{\sim}100$ beads and 50 ml lead solution in a 250-ml Erlenmeyer flask, while, at over 100 beads, uptake of the lead decreased. The order of biosorption capacity for heavy metals was Pb>Cu>Cd. Pb uptake capacity of the immobilized A. niger beads treated with 0.1 M $CaCI_2$, 0.1 M NaOH, and 0.1 M KOH decreased compared to the untreated beads. On testing the desorption of Pb from the immobilized A. niger beads, re-uptake of Pb was found possible after desorption of the binding metal with 0.1 M HCI.

• Journal of Sericultural and Entomological Science
• /
• v.18 no.2
• /
• pp.89-93
• /
• 1976

The physiological saline solution for animals is known as Ringer's solution which is used for keeping the function of cold blooded vertebrate animals. Primaily the saline solution is used for the purpose of perfusion experiment in frogs. Later the saline solution is applied in several kinds of animals including human being with satisfactory results. However, this saline solution was introduced to silkworm and it was found that the result was not as successful as in the case of other animals and human being. Normally, in the case of silkworm, the physiological saline solution is prepared in order to maintain the normal function of separated organs and tissues. To this end, the saline solution is adjusted to contain the certain amount and strength of ions, osmosis pressure and hydrogen concentration. The most of cases, the physiological saline solution should be prepared so that the constituent of the solution be the same with the blood selium and body fluid. The hydrogen concentration in the ion element of the saline solution is adjustable by adding Na$\^$＋/, K$\^$＋/, Ca$\^$＋＋/, Mg$\^$＋＋/ which are followed by adding of buffer solution such as NaHCO$_3$and NaH$_2$PO$_4$. Determination of optimum concentration of cation in the physiological saline solution, and the optimum mixing rate of more than two kinds of cations are based on the movement of dorsal vessel in the silkworm larvae. The optimum concentration of cations in the solution is prepared by adding NaCl solution which is under zero point. However, this solution was further added with the different concentration of KCl and CaCl$_2$. By dropping the prepared solution on the 5th larvae, the effects of solution was measured. The measurement was done by observation of movement' of dorsal vessel and its time length, and the number of pulses. According to the experiment, it was found that when only NaCl solution was applied, the number of pulses is increased for a moment, and the pulse stopped after one hour or so. When KCl solution was added the time of pulse was prolonged and in the contrast, the number of pulses was slow down. If KCl and CaCl$_2$solutions are added the time of pulse was further prolonged. Even though the adding of KCl and CaCl$_2$are found to be effectible, the correlation between the concentration of solution and the movement of dorsal vessel was not observed. However, it was same in the case of adding Ca$\^$＋＋/ or K$\^$＋/. It was found that when Mg$\^$＋＋/ was added to dorsal vessel the number of the pulses was not decreased although the prolonged time pulse was observed.