• 한국지하수토양환경학회지:지하수토양환경
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• 제21권3호
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• pp.35-48
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• 2016

A micromodel was applied to estimate the effects of geological conditions and injection methods on displacement of resident porewater by injecting scCO₂ in the pore scale. Binary images from image analysis were used to distinguish scCO₂-filled-pores from other pore structure. CO₂ flooding followed by porewater displacement, fingering migration, preferential flow and bypassing were observed during scCO₂ injection experiments. Effects of pressure, temperature, salinity, flow rate, and injection methods on storage efficiency in micromodels were represented and examined in terms of areal displacement efficiency. The measurements revealed that the areal displacement efficiency at equilibrium decreases as the salinity increases, whereas it increases as the pressure and temperature increases. It may result from that the overburden pressure and porewater salinity can affect the CO₂ solubility in water and the hydrophilicity of silica surfaces, while the neighboring temperature has a significant effect on viscosity of scCO₂. Increased flow rate could create more preferential flow paths and decrease the areal displacement efficiency. Compared to the continuous injection of scCO₂, the pulse-type injection reduced the probability for occurrence of fingering, subsequently preferential flow paths, and recorded higher areal displacement efficiency. More detailed explanation may need further studies based on closer experimental observations.

• Ocean and Polar Research
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• 제31권1호
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• pp.71-76
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• 2009

Drastic changes in the water quality and phytoplankton community of the new Saemankeum Lakeduring the first decade following the construction of the Saemankeum Sea Wall has been considered to be unavoidable. Input of eutrophicated water through the Mankyeong River and Dongjin River might produce more direct effects on the water quality and phytoplankton community, which lead us to launch a long-term semi-weekly investigation at the "Mankyeong Bridge" monitoring point to resolve its short-term effect as well as long-term stabilization of the ecosystem in the new Saemankeum Lake. During 15 months starting from June 2006, the water temperature varied in accordance with the typical seasonal variations in temperate on the coasts, and no significant daily variations evoked by tidal cycle could be detected. However, there was an inverse relationship between seasonal precipitation and salinity even though the range in annual variation was drastically reduced right after the construction of the Saemankeum Sea Wall. Species richness in the phytoplankton community was also reduced due to the narrowed annual range of salinity, which would eliminate the mid-high salinity species from the Mankyeong Bridge monitoring point. Similarly, species diversity was decreased with increased dominance of the phytoplankton community after the construction. Between the two summer seasons during the present study, species diversity was higher in 2007 than in 2006, which might indicate the early stage of a gradual stabilization in the ecosystem including the phytoplankton community at the monitoring station. The phytoplankton community thus needs to be monitored on a long-term basis to identify indirect signals that can be used to assess the stability of the ecosystem in the young Saemankeum Lake.

• 환경생물
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• 제32권2호
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• pp.129-137
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• 2014

Heterosigma akashiwo의 대발생 기작을 규명하기 위하여 환경 요인들에 따른 성장률을 각각 비교하였다. 환경요인, 염분, N:P ratio, 철 (Fe), 셀레늄 (Se)을 대상으로 국내 배양주 2종과 국외 배양주 1종의 성장 특성을 확인하였다. 그 결과, H. akashiwo 배양주는 염분과 철의 농도에 따른 최대 성장률의 특성을 기반으로 지리학적 특이성을 찾기는 힘들었으나, 염분에 대한 내성은 강하여 10 psu에서 40 psu에서 생존이 가능한 것으로 나타났다. N:P ratio와 셀레늄은 국내 배양주와 국외 배양주의 차이를 보였다. 이와 같은 생리학적 특성에 대한 결과를 보았을 때, H. akashiwo가 염분에 대한 높은 내성을 기반으로 우점할 수 있으며, 풍부한 영양염을 이용하여 더욱 빠른 성장으로 대발생을 가능하게 할 수 있을 것이라고 판단된다.

• 한국식생활문화학회지
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• 제14권5호
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• pp.455-460
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• 1999

In order to establish the processing condition of salt-fermented liquefaction of sardine (Sardinops melanoslicta), effect of temperature, pH value, and concentration of salinity on crude enzyme activity of sardine viscera were investigated. The optimum temperature range of crude enzyme activity in sardine viscera was $45{\sim}50^{\circ}C$ and the optimum pH value of it was 9.8. According to the concentration of salinity increased the crude enzyme activity in sardine viscera decreased. The relationship between concentration of salinity (X) and the crude enzyme activity (Y) in sardine viscera is shown as follows; Y=-0.01363X+0.7676 (r=-0.88). For the purpose of processing conditions of rapid- and low salt-fermented liquefaction of sardine, changes of viable cell count, histamine content, and volatile basic nitrogen (VBN) in the chopped whole sardine with 8% NaCl during preheating process at $40^{\circ},\;45^{\circ}$ and $50^{\circ}C$ for 48 hrs were analyzed. During preheating, initial viable cell counts of chopped whole sardine were $10^{4-7}/g$, but they decreased $10^{1-5}/g$ after 48 hrs. Histamine contents during preheating process at $40^{\circ}\;and\;45^{\circ}C$ were gradually increased, whereas at $50^{\circ}C$ were almost the same level after 48 hrs. VBN contents were continuously increased during preheating, but preheating at $50^{\circ}C$ samples were lower level than that of $40^{\circ}\;and\;45^{\circ}C$ ones. For the purpose to accelerate the fermentation and liquefaction of chopped whole sardine, preheating at optimum temperature of crude enzyme activity for 48 hrs was useful processing method and the contents of viable cell count, histamine, and VBN were safety level for food sanitation.

• 한국식품조리과학회지
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• 제28권6호
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• pp.753-761
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• 2012

Although the mackerel is an excellent food, there are disadvantages of its own smell and its shelf-life. So this study aimed to examine the quality assessment, shelf-life and acceptability of mackerel marinated with different amounts of thyme extract through the salinity, pH, texture, change of color, and sensory evaluation for reducing the smell of it and improving the shelf-life and acceptability of it with the thyme of various physiologic activities. The salinity of mackerel marinated with different amounts of thyme was a lower 2% than that of the existing salted mackerel, 5%, when producing the salted mackerel in the experimental method of this study, reducing the intake of salt. The shelf life of the existing salted mackerel was up to 4 weeks, while that of the salted mackerel marinated with thyme extract was up to 5 weeks. The change in pH during storage showed that the salted mackerel marinated with thyme extract after 5 weeks were within the initial decomposition of dark-fleshed fishes, pH 6.2-6.4, which the shelf life was extended due to the preservative effect of antioxidant content. The acceptability test showed that T 1 marinated with 1% thyme extract was ideal in all flavor, taste and general acceptability.

• 해양환경안전학회지
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• 제13권1호
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• pp.29-37
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• 2007

1971년부터 2001년까지 해양 및 기상관측 자료를 활용하여 한국 서해에서 기상인자(기온, 바람, 강수량)가 수온과 염분 변화에 미치는 영향을 분석 하였다. 그 결과 수온-기온, 수온-강수량, 염분-풍속은 정상관(+)을, 수온-풍속, 염분-기온, 염분-강수량은 역상관(-)의 관계를 보였다. 기상인자와 해양인자간의 시간지연(time lag)은 표층에서 $0{\sim}4$개월, 저층까지 기상의 영향이 도달하는 데에는 표층보다 $0{\sim}4$개월의 시간지연이 더 있었다. 수온은 같은 해의 기온 변화의 영향을 크게 받는 반면, 염분은 그 직전해의 강수량의 영향을 크게 받았다. 풍속의 강약에 따라 수온, 염분의 변동 폭 또한 함께 변하였다.

• 한국환경과학회지
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• 제16권10호
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• pp.1119-1125
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• 2007

We examined the horizontal distribution of salinity and the concentrations of DIN and DIP after heavy rain-fall events in coastal areas of South Korea from Yeoja Bay to Narodo and from Gwangyang Bay to Geomodo to determine whether fresh water actually flows into areas of Cochlodinium polykrikoides red tides and to observe its effect on the growth of this organism after heavy rainfall. Following heavy rainfall (155 mm) in the Yeosu and Suncheon regions, the average salinity was 21 and 29 psu at Yeoja Bay and in the coastal waters of Narodo, respectively. After 126 mm of rainfall, the values were 19 and 25 psu in the coastal waters of Yeosu and Geomodo, respectively. This may have been caused by an influx of fresh water, after the rainfall event, into the open sea coastal areas around Narodo and Geomodo from the Dong and Seomjin Rivers, which are about 3540 km away. After the rainfall, the concentrations of $NH_4-N,\;NO_2-N$, and $PO_4-P$ were slightly increased; however, the concentration of $NO_3-N$ was greatly increased and diffused throughout the coastal areas of Narodo and Geomodo, which frequently experience C. polykrikoides blooms. The influence of $NH_4-N,\;NO_2-N$, and $PO_4-P$ on the occurrence of C. polykrikoidesred tides in coastal areas around Narodo and Geomodo after heavy rainfall does not appear to be great. Instead, the occurrence C. polykrikoides red tides in the coastal areas of Narodo and Geomodo seems to be facilitated by $NO_3-N$.

• 한국자원식물학회지
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• 제16권3호
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• pp.181-186
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• 2003

간척지 논에서 쌀 생산을 위한 기초 자료를 얻고자 2000년 전남 광양만 간척지에서 토양염분농도별 수량과 토양의 이화학적 조성간의 관계를 검토한 결과는 다음과 같다. 1. 출수기는 0.1%의 염분농도 토양은 8월 15일, 0.4%의 염분농도 토양은 8월 20일, 0.8%의 염분농도 토양은 8월 25일로서 0.1%의 염분농도 토양이 가장 빨랐다. 2. 쌀수량은 토양의 염분농도가 0.1%로 낮은 토양이 599kg/10a로 가장 많았고, 다음으로는 0.4%의 염분농도 토양이 568kg/10a이었고 0.8%의 염분농도 토양은 446kg/10a로 가장 낮았으며 쌀수량 구성 요소 역시 같은 경향으로 0.1%의 염분농도 토양에서 가장 우수하였고 다음으로는 0.4%, 0.8%순으로 나타났었다. 3. 쌀수량과 토양의 이화학적 특성간의 상관에서는 pH와는 부의상관, 유기물, 인산, 질소, 가리, 칼슘, 마그네슘의 함량간에는 정의 상관이었다. 4. 전남광양만 간척지에서 쌀수량과 수량구성 요소면에서 볼 때에 적합한 토양의 염분농도는 0.1%이라고 사료된다.

• 한국수산과학회지
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• 제54권5호
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• pp.761-768
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• 2021

This study was carried out to identify an effective method to acclimate low-salinity (4 psu) bred Litopenaeus vannamei (mean body weight 16±3.3 g) to sea water. The fast acclimation group (FA) was directly exposed to filtered sea water (32 psu) while the slow acclimation group (SA) was exposed to a slow increase in salinity. Shrimps were sampled at 0, 1, 3, 6, 12, 24 and 48 h for plasma analyses. The plasma components between experimental groups did not show significant differences. The hemolymph osmolality (HO) in FA increased significantly after 1 h (P<0.05), while in SA it started to increase slowly only at 24 h and reached a similar level to that of FA at 48 h. The levels of Na⁺ and Mg²⁺ ions were significantly different between the two treatments (P<0.05), but there was no significant difference in Ca²⁺ ion levels. We found that the different methods of acclimation of L. vannamei to sea water do not affect the plasma components significantly, but lead to changes in the HO and ion levels, it is considerable to acclimate gradually for at least two days.

• 한국작물학회지
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• 제69권1호
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• pp.1-14
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• 2024

High soil salinity is the most severe threat to global rice production as it causes a significant decline in rice yield. Here, we investigated the effects of various plant extracts on rice plant stress associated with high salinity. Additionally, we examined various physiological and biochemical parameters such as growth, photosynthetic activity, chlorophyll content, and lipid peroxidation - in rice plants after treatment with selected plant extracts under salt stress conditions. Of the 11 extracts tested, four - soybean leaf, soybean stem, moringa (Moringa oleifera), and Undaria pinnatifida extracts - were found to effectively reduce salt stress. A reduction of only 3-23% in shoot fresh weight was observed in rice plants under salt stress that were treated with these extracts, compared to the 43% reduction observed in plants that were exposed to stress but not given plant extract treatments (control plants). The effectiveness varied with the concentration of the plant extracts. Water content was higher in rice plants treated with the extracts than in the control plants after 6 d of salt stress, but not after 4 d of salt stress. Although photosynthetic efficiency (Fv/Fm), electron transport rate (ETR), and the content of pigments (chlorophyll and carotenoid) varied based on the types and levels of stress and the extracts that the rice plants were treated with, generally, photosynthetic efficiency and pigment content were higher in the treated rice compared to control plants. Reactive oxygen species (ROS), such as superoxide radicals, hydrogen peroxide (H₂O₂), and malondialdehyde (MDA), increased as the duration of stress increased. ROS and MDA levels were lower in the treated rice than in the control plants. Proline and soluble sugar accumulation also increased with the duration of the stress period. However, proline and soluble sugar accumulation were lower in the treated rice than in the control plants. Generally, the values of all the parameters investigated in this study were similar, regardless of the plant extract used to treat the rice plants. Thus, the extracts found to be effective can be used to alleviate the adverse effects of stress on rice crops associated with high-salinity soils.