• Korean Aquaculture
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• v.19 no.1
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• pp.43-51
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• 2007

말라카이트그린(MG) 및 L-말라카이트그린(LMG)의 소멸은 뱀장어 Anguilla anguilla 유생에서 100일정도 걸린다. 실뱀장어(평균체중: 4.1 g)가 $23.0-26.5^{\circ}C$의 다양한 수온범위에 24시간동안 아주 낮은 농도(0.1 mg/l MG)에 약욕을 실시하였다. 처리한 후 실뱀장어는 말라카이트그린이 없는 깨끗한 물이 들어 있는 수조로 옮겼다. 뱀장어가 수용된 수조에는 순환여과 된 사육수를 공급하였다. 일정한 시간 간격으로 수집된 10마리의 뱀장어 및 사육수의 샘플은 high-performance liquid chromatography (HPLC)으로 분석하였다. 말라카이트그린의 가장 높은 농도는 $435{\pm}59\;{\mu}g/kg(mean{\pm}S.D.)$로서 처리시작 후 6시간에서 나타났다. L-말라카이트그린(LMG) 대사물의 농도는 비교적 높게 나타났으며 ($>100\;{\mu}g/kg$), 처리시작 후 6시간 및 처리종료 후 1500시 사이에서 안정적으로 나타났고 최대농도는 $831{\pm}231\;{\mu}g/kg$이었다. 비록 뱀장어는 체중이 증가하지는 않았지만 노출 후 24시간 후에도 L-말라카이트그린(LMG)은 여전히 전어체 kg당 $15{\pm}12\;{\mu}g/kg$ 함량이 존재하였다. 말라카이트 그린은 처리 이후 1920 및 2400시에서는 발견되지 않았다. 생물적 여과사육수와 순환여과시스템에서는 말라카이트그린이 발견되지 않았다. 본 연구에서는 부가적으로 빠르게 성장하여 11개월 된 뱀장어 두 마리를 샘플하여 분석에 사용하였다. 두 마리의 뱀장어는 실뱀장어기(0.3g)일 때 $0.15\;mg\;l^{-1}$ 농도의 말라카이트그린이 처리되었었다. 뱀장어의 근육조직에서는 지질 크로마토그래피-질량 분광광도계분석에 의해 말라카이트그린과 L-말라카이트그린이 측정 가능한 양으로 함유되지 않음을 확인할 수 있었다($<\;0.2\;{\mu}g\;kg^{-1}$).

• Fire Science and Engineering
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• v.18 no.2
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• pp.41-48
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• 2004

We have conducted a numerical simulation under three-dimensional unsteady conditions in order to analyze the characteristics of $CO_2 $;, extinguishant transfer by varying the location of the injection nozzle, which affects the effect of a $CO_2 $;, fire fighting system used in the form of fixed systems for the marine engine room. Flow fields and $CO_2 $;, concentration fields were measured according to the location of the injection nozzle. In the case of arranging the injection nozzle on the center of the ceiling, the low-normal concentration distribution was developed along the $CO_2 $;, jet due to the downward flow created by impinging ceiling jets in the symmetric plane. The concentration line reaches its peak due to the mass transfer of $CO_2 $;, at the comer.

• Journal of the Korean earth science society
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• v.31 no.6
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• pp.600-607
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• 2010

In 2008, multiple episodes of large-scale transport of natural airborne particles and anthropogenically affected particles from different sources in the East Asian continent were identified in the National Oceanic and Atmospheric Administration (NOAA) satellite RGB-composite images and the mass concentrations of ground level particulate matters. To analyze the aerosol size distribution during the large-scale transport of atmospheric aerosols, both aerosol optical depth (AOD; proportional to the aerosol total loading in the vertical column) and fine aerosol weighting (FW; fractional contribution of fine aerosol to the total AOD) of Moderate resolution Imaging Spectroradiometer (MODIS) aerosol products were used over the East Asian region. The six episodes of massive natural airborne particles were observed at Cheongwon, originating from sandstorms in northern China, Mongolia and the loess plateau of China. The $PM_{10}$ and $PM_{2.5}$ stood at 70% and 16% of the total mass concentration of TSP, respectively. However, the mass concentration of $PM_{2.5}$ among TSP increased as high as 23% in the episode in which they were flowing in by way f the industrial area in east China. In the other five episodes of anthropogenically affected particles that flowed into the Korean Peninsula from east China, the mass concentrations of $PM_{10}$ and $PM_{2.5}$ among TSP reached 82% and 65%, respectively. The average AOD for the large-scale transport of anthropogenically affected particle episodes in the East Asian region was measured at $0.42{\pm}0.17$ compared with AOD ($0.36{\pm}0.13$) for the natural airborne particle episodes. Particularly, the regions covering east China, the Yellow Sea, the Korean Peninsula, and the east Korean sea were characterized by high levels of AOD. The average FW values observed during the event of anthropogenically affected aerosols ($0.63{\pm}0.16$) were moderately higher than those of natural airborne particles ($0.52{\pm}0.13$). This observation suggests that anthropogenically affected particles contribute greatly to the atmospheric aerosols in East Asia.

• Journal of Aquaculture
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• v.17 no.4
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• pp.268-274
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• 2004

Olive flounder was treated with oxytetracycline (OTC) and changes in blood physiology, antioxidant enzymes and heat shock protein (HSP) were recorded to obtain preliminary data for optimal OTC treatment. Blood parameters were measured 1 and 3 h after the OTC treatments at the concentration of 0 (control), 100, 300 and 500 ppm for I h. Hematocrit decreased with time, however the difference was not significant (P>0.05). Reduced number of red blood cell was observed with increasing OTC concentration. Serum glucose level increased as the OTC concentration increased. However, glucose level was similar to control after 3 h. Blood total protein decreased immediately after the OTC treatment but increased after 1 and 3 h. However, the increment in blood total protein was low. Activities of superoxide dismutase enzymes in 300 and 500 ppm groups increased by the OTC concentration. Catalase enzyme activity was negatively affected by the OTC concentration. However, the differences were not significant (P>0.05). High expression of HSP-70 protein was recorded for groups treated with 100 and 500 ppm compared to that of the control group. However HSP-70 mRNA showed a lower increment which was not significant (P>0.05).

• Journal of the Korean earth science society
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• v.43 no.1
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• pp.77-90
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• 2022

Despite the decreasing trend of anthropogenic emissions in East Asia in recent years, haze days still frequently occur in spring. Atmospheric blocking, which occurs frequently in the northeastern Pacific, leads to persistent changes in large-scale circulation and blocks westerly flow in the East Asian region. During March 2019, frequent warm and stagnant synoptic meteorological conditions over East Asia were accompanied 6-7 days later by the Alaskan atmospheric blocking. The Alaskan atmospheric blocking over the period of March 18-24, 2019 led to high particulate matter (PM₁₀) severe haze days exceeding a daily average of 50 ㎍ m^-3 over the period of March 25-28, 2019 in South Korea. Although the high-PM₁₀ severe haze days were caused by warm and stagnant meteorological conditions, the regional contribution of anthropogenic emissions in eastern China was calculated to be 30-40% using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). The major regional contributions of PM₁₀ aerosols in the period of high-PM₁₀ severe haze days were as follows: nitrates, 20-25%; sulphates, 10-15%; ammonium, 5-10%; and other inorganics, 15-20%. Ammonium nitrate generated via gas-to-aerosol conversion in a warm and stagnant atmosphere largely contributed to the regional transport of PM₁₀ aerosols in the high-PM₁₀ severe haze days in South Korea.

• KSBB Journal
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• v.15 no.2
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• pp.195-200
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• 2000

Studies were made on the optimization of media to c비tivate Thraustochytrium aureum A TCC 34304 for the enhanc엉d p production of linoleic acid. The medium optimization was made with the artificial sea water medium. Yeast extract, sodium g glutamate, peptone and tryptone were considered as nitrogen source. The effect of $\infty$ncentration of nitrogen source as well a as initial glucose on the production of linoleic acid were investigated to optimize the media. The maximum yield of lipid was 0 0.302 mg/g cell mass when initial glucose $\infty$ncentration was 10 g/L and sodium glutamate was used as nitrogen source, a and the yield of linoleic acid to unit cell mass was also maximum to be 8 % in that case. The highest linoleic acid c concentration was obtained in the initial glucose concentration 30 g/L regardless of the kinds of nitrogen source and the | linoleic acid concentration was 0.208 g/L when peptone was supplemented to be 2 g/L.

• Korean Journal of Ecology and Environment
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• v.34 no.4 s.96
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• pp.327-336
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• 2001

Physical, chemical, and biological parameters were measured during the period from July 1993 to August 1994 near the Munui intake tower of Taechung Reservoir to evaluate effects of nutrients and suspended solids on algal chlorophyll-a and water clarity. Large amounts of precipitation during summer 1993 produced minimum conductivity ($88\;{\mu}S/cm$), minimum TN : TP (<40), and maximum total phosphorus (TP;$59\;{\mu}g/L$) and resulted in a chlorophyll-a peak ($79\;{\mu}g/L$) and minimum transparency (<1.5 m) among the seasons. At the same time, ratios of volatile suspended solids (VSS): non-volatile suspended solids (NVSS) were maximum (13.0),indicating that the reduced transparency was mainly attributed to biogenic turbidity in relation to phytoplankton growth. In contrast, severe drought in summer 1994 resulted in greater conductivity (>$120\;{\mu}S/cm$), water clarity (%gt;2 m), and lower TP and chlorophyll- a (<$10\;{\mu}g/L$) relative to those of summer 1993. Total phosphorus ($R^2=0.46$, n=59) accounted more variations of chlorophyll- a compared to total nitrogen ($R^2=0,29$, n=59). The mass ratios of TN : TP ranged from 39 to 222 and were strongly correlated with TP (r = -0.80) but not with concentrations of TN (r = 0.05). Ambient nutrient concentrations and TN : TP mass ratios indicated that seasonality of chlorophyll- a was likely determined by concentrations of phosphorus reflected by the distribution of rainfall. It was concluded that reductions of phosphorus during heavy rainfall may provide better water quality for the drinking water in the intake tower.

• Resources Recycling
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• v.29 no.1
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• pp.25-34
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• 2020

Electrochemical Quartz Crystal microbalance is a tool that is capable of measuring nanogram-scale mass change on electrode surface. When applying alternating voltage to the quartz crystal with metal electrode formed on both sides, a resonant frequency by inverse piezoelectric effect depends on its thickness. The resonant frequency changes sensitively by mass change on its electrode surface; frequency increase with metal dissolution and decrease with metal deposition on the electrode surface. The relationship between resonant frequency and mass change is shown by Sauerbrey equation so that the mass change during metal dissolution can be measured in real time. Especially, it is effective in the case of reaction mechanism and rate studies accompanied by precipitation, volatilization, compound formation, etc. resulting in difficulties on ex-situ AA or ICP analysis. However, it should be carefully considered during EQCM experiments that temperature, viscosity, and hydraulic pressure of solution, and stress and surface roughness can affect on the resonant frequency. Application of EQCM was shown as a case study on leaching of platinum using aqueous chlorine for obtaining activation energy. A platinum electrode of quartz crystal oscillator with 1000 Å thickness exposed to solution was used as leaching sample. Electrogenerated chlorine as oxidant was purged and its concentration was controlled in hydrochloric acid solution. From the experimental results, platinum dissolution by chlorine is chemical reaction control with activation energy of 83.5 kJ/mol.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.3
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• pp.435-443
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• 2012

This study investigated soil carbon storage and microbial activities influenced by different management practices in rice paddies and pastures. Soils under a single-crop farming of rice (CON) and rice-Italian ryegrass rotation farming (IRG) were compared in Jangheung, Jeollanam-do, Seocheon and Cheonan, Chungcheongnam-do. Soils from pastures were analyzed to investigate the effect of duration period (P1, P2, P3) in Namwon, Jeollabuk-do and Seosan, Chungcheongnam-do. In rice paddy, total and particulate carbon (PC) concentrations in the IRG soils were significantly higher than those in the CON soils both in Jangheung and Seocheon where the IRG has been established for three years, whereas carbon concentrations were not significantly different in Cheonan where IRG planting history is only one year. In rice paddy soils, PC was suggested as an early indicator to monitor changes in soil carbon storage followed by adopting different management practices. In pasture, total and PC concentrations increased with duration period especially in the 0-5 cm soils. Contrary to the rice paddy soils, the magnitude of change in PC concentration is not as great as that in total carbon concentration, implying that there is a need to develop a new early indicator other than PC using different fractionation scheme. The soil carbon storage in pasture also increased with years since establishment and the increasing rate was significantly greater in the early stage (0-5 yrs) than the later one (> 5 yrs). Microbial activities measured from fluorescein diacetate (FDA) hydrolysis analysis were significantly lower in the IRG soils than CON soils, whereas no difference was observed in the pastures of different ages. This shows that FDA activity is not a sensitive indicator to differentiate soil qualities influenced by management practices if it is used by itself.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.4
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• pp.403-408
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• 2011

Purpose: To study the concentration distribution and diffusion depth in tinted lenses using the law of diffusion. Methods: The measured values taken from experiments were fitted with the theoretical fitting curve induced on the basis of Fick's second law of diffusion. Results: The fitting curves were in very good agreement with the measured values. As the results, we found the quantitative relationship between mass of dye solution diffused into the tinted lens per unit area and dyeing time, and evaluated concentration distribution of dye in tinted lens, diffusion depth, etc. Conclusions: The dyeing mechanism of tinted lenses can be well described by diffusion theory.