• Journal of Korean Society of Environmental Engineers
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• v.31 no.4
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• pp.308-323
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• 2009

This review paper serves to describe the composition and activity of biological activated carbon (BAC) biofilm which is considered as a progressive process for water treatment. As well as several physical-chemical, biochemical and microbiological analysis methods for characterizing the composition and activity of BAC biofilm, the ability of the biofilm to remove and biodegrade organic matters and pollutants related to other water treatment processes such as pre-ozonation will be reviewed. In this paper, conversion of GAC into BAC, removal mechanism of pollutants, characteristics and affecting factors of BAC biofilm, and modeling of BAC are described in detail. In addition, strategies to control the growth of the BAC biofilm, such as varying the nutrient loading rate, altering the frequency of BAC filter backwashing and applying oxidative disinfection, will be dwelled on related to their respective process control challenges.

• 한국지구과학회:학술대회논문집
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• 2010.04a
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• pp.101-102
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• 2010

규화목은 목본식물의 2차목부가 화석화된 것으로 화석화 과정에서 여러 종류의 무기물이 세포를 치환하거나 세포의 내강 또는 간극에 침투하여 고화된 것이다. 이 과정에서 목재의 해부학적 구조가 잘 보존되는 경우가 많고 이를 통해 목재의 수종을 비교적 정확히 동정할 수 있을 뿐만 아니라 과거 환경에 대한 정보를 얻을 수 있다. 목재는 유관속 형성층에 의해 매년 새롭게 형성되어 축적되며 형성된 조직은 성장하는 당해 기후변화를 반영하게 된다. 따라서 화석목재를 통해 과거 기후조건을 복원할 수 있는 정보를 얻을 수 있는 경우도 많다). 본 연구는 포항 분지의 신제3기 마이오세 장기층군에서 채집한 규화목의 조직과 나이테 분석을 통해 고환경을 해석한 것이다. 장기층군에서 채집한 15개의 규화목 표본 중 나이테가 잘 나타나는 5개 표본에서 나이테를 분석하고 그중 조직이 잘 보존된 1개의 표본에 대해 목재해부학적 연구를 수행하였다. 나무가 성장함에 따라 나타나는 나이테의 폭은 환경적 요인 등으로 매년 일정하지 않다. 이런 인접연륜간의 연륜변동성을 알아보기 위해 연륜연대학(Dendrochronology)에서 널리 사용되는 평균민감도 측정 방법을 사용하였다. 평균민감도는 연륜변동이 어느 정도있느냐를 알아보는 것으로 인접한 연륜들 사이의 차이를 측정하여 인접연륜간 연륜변동성을 나타낸다. 평균민감도 값이 크면 연륜폭 변동이 크다는 것을 의미하며 나무가 자라는 당시 환경인자의 변화량이 컸다고 해석할 수 있다. 조직이 잘 보존된 1개의 표본은 목재해부학적 특징상 느릅나무과(Ulmaceae) 느릅나무속(Ulmus)으로 동정되었다. 또한 5개 표본의 나이테를 분석한 결과 평균민감도는 0.34~0.41 범위를 나타내며 전체 평균은 0.37의 값을 갖는 것으로 나타났다. 이것은 규화목 생성 당시 환경이 온대기후를 지시하며, 물 공급이 매년 계절적인 제한을 받았거나 다양한 변화가 있어 계절적으로 강수량 변화가 있었음을 지시한다.

• KSBB Journal
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• v.15 no.1
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• pp.100-105
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• 2000

Optimal medium composition, culture conditions, characteristics of phase variation and activity of insecticidal toxin by Xenorhabdus nematophilus isolated and identified from Korean entomopathogenic nematode Steinernema carpocapsae were examined. Optimal medium composition of this strain was 50-70 g/L yeast extract, 3 g/L $K_{2}HPO_{4}$, 1g/L $NH_{4}H_{2}PO_{4}$, 2g/L ${MgSO}_4$$\cdot$${7H}_{2}O$, 10g/L NaCl and, these, yeast extract was found as a limiting nutrient for cell growth. When Monod equation was applied, maxmum specific growth rate and Monod constant were estimated as 0.13 $hr^{-1}$ and 20g/L, respectively. The pH of culture medium increased up to 8.5-9.5 regardless of initial pH 6-7 as the cells continued to grow. The specific growth rate in a 7 L fermentor was 0.18 $hr^{-1}$, which was enhancement 1.4 fold compared to a flask culture. In case of phase variation, phase I fraction was maintained above 90% at the stationary phase for both flask and fermentor cultures. According to oral toxicity test of Gallena mellonella by Xenorhabdus nematophilus, the addition of cell pellets into feed inhibited normal growth of insect larvae and killed completely then after 20 days cultivation. When culture supernatant of this strain was injected into hemolymph of insect larva, the toxicity was strongest at 24hr cultivation in the early exponential phase and gradually decreased as the culture time proceeded.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.3
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• pp.139-144
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• 2005

To investigate the long-term variation of water qualities, we have daily monitored physio-chemical characteristics of surface water in the Geum River estuary from June 1996 to April 2004. We found that the water qualities were determined by three dominant factors : 1. fluvial input from Geum River ($28.3\%$), 2. chemical processes such as nitrification and phosphate addition originated from sediment resuspension and domestic sew- age input ($18.6\%$), 3. biological processes such as nutrient consumption by primary producers ($13.5\%$). The factor 1 (fluvial input) effectively affected the water quality of the estuary particularly during the normal or low river discharge. The factor 2 (chemical processes) and the factor 3 (biological processes) showed distinct seasonal differences due to their relative strengths of biological activities. The factor 3 was a governing parameter during the period of spring algal bloom in 2004. For the spring period, an empirical equation derived from the multi-regression analyses showed that the in-situ chlorophyll-a distributions in the estuarine water were successfully simulated by the phosphate concentrations and N/P ratios. Therefore we suggest that phosphate functions as a limiting factor for the primary productivity in the Geum River estuary for the dry season, especially during spring.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.4
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• pp.274-285
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• 2016

In order to elucidate the spatiotemporal variations of marine environmental parameters, we collected seawater samples in the middle east coast of Korea in 2013-2014. A high temperature and low salinity were distinctively observed in the summer and a low temperature and high salinity pattern in the winter. The temperature of the bottom water was in the range of $2^{\circ}C$ to $7^{\circ}C$, with the temperature being relatively high in the winter, while the salinity was measured to be around 34, with no large differences across the seasons. The dissolved oxygen concentrations were in the range of $7mg\;L^{-1}$ to $12mg\;L^{-1}$, and it was relatively high in May compared to other seasons. The seawater temperature and dissolved oxygen concentration at the surface layer showed a significant negative correlation in the autumn and winter seasons, based on which it is seemed that water temperature is the main factor controlling the amount of dissolved oxygen in the autumn and winter seasons. The dissolved inorganic nitrogen (DIN) and silicate (DSi) increased 11- and 7-fold, respectively, in the winter compared to the summer. The DIN to DIP (dissolved inorganic phosphorus) ratio for the surface seawater was approximately 16, but it was relatively low in the spring season. On the other hand, the DIN to DIP ratio was relatively high in the summer. Based on this, it is seemed that nitrogen and phosphorus were the growth-limiting nutrients for phytoplankton in the spring and summer, respectively. Water quality was I (excellent) ~III (medium) level at the most stations except for some stations (level IV) during the autumn season, having low dissolved oxygen saturations.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.2
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• pp.105-112
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• 2008

The surface and bottom water were sampling in ten stations of the coastal area of Chagwi-Do, Jeju Island, which was repeated 6 times in several different months(September, November, 2004 and March, May, August, and November 2005) in order to examine the physico-chemical characteristics of water. The temperature varied by approximately $16^{\circ}C$, ranging somewhere between 1$12.2^{\circ}C$ and $28.9^{\circ}C$. Specifically, the temperature of bottom water was $13^{\circ}C$, implying the emergence of low temperature water. The salinity ranged from 30.2 to 34.9%o, and the lowest salinity in August may be attributable to the effect of land-based water. N/P ratio, the growth factor of phytoplankton, ranged from 5 to 76, which varied depending on the season and station. The ratio, however, was over 22 on the average, suggesting that phosphate phosphorus is an factor that restricts the growth of phytoplankton. TOC in the concentration of organic carbon ranged between $92.5{\mu}M$ and $438.3{\mu}M$, and the mean was $217{\mu}M$. DOC ranged from $82.5{\mu}M$ to $299.2{\mu}M$, and the mean was $130{\mu}M$. The ratio of DOC/POC was 60% with abundant dissolved organic carbon.

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.383-392
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• 2013

The objective of this study was to determine the effects of N:P ratio on primary productivity measured as chlorophyll-a (CHL) using the approach of In Situ Nutrient Enrichment Bioassays (NEBs) in Daechung Reservoir. The effects of NEBs on the N:P mass ratios were compared with the field data obtained from monthly-chemical monitoring during 2009~2012. The short-term NEBs showed that the response of primary productivity in the phosphorus spiked treatments (5, 15, 20 and 30 N:P ratios) were greater than the responses in the control (C) and nitrogen spiked treatment (N:P ratio=150, $T_{VI}$). The response in the nitrogen treatment (N:P ratio=150, $T_{VI}$) was less compared to control and all five treatments ($T_I{\sim}T_{VI}$). The outcomes of the NEBs suggest that phosphorus limited the phytoplankton growth and nitrogen addition inhibited the algal growth. In the analysis of nutrients and CHL from the ambient epilimnetic water in Daechung Reservoir, minimum N:P ratios resulted in maximum concentrations of CHL. Overall, our results suggest that the N:P ratio was the key factor in regulating the phytoplankton growth in NEB experiments.

• Journal of Life Science
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• v.27 no.1
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• pp.72-77
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• 2017

Inorganic iron is essential for various metabolic processes, including RNA synthesis, electron transport, and oxygen detoxification in microorganisms. Many bacterial pathogens compete for iron acquisition in diverse environmental condition such as host. Salmonella Typhimurium SL1344 also requires inorganic iron as a cofactor for growth. When a M9 minimal liquid medium was supplemented with ethylenediamine di-o-hydroxyphenylactic acid (EDDA) which acts as an iron-chelating agent, growth of Salmonella Typhimurium SL1344 in the supplemented medium was completely arrested by deficient of useful iron under iron-depleted condition. However, a number of siderophores, which are small, high-affinity iron chelating compounds secreted by microorganisms such as bacteria and fungi, were produced for utilization of restricted iron under iron-depleted condition. A M9 minimal liquid medium complemented with human transferrin (hTf)-iron complex turned completely off production of siderophores, but growth of Salmonella Typhimurium SL1344 maintained level similar to compare one complemented with iron (III) chloride (FeCl3). This means that human transferrin (hTf)-bound iron can utilize via directly interaction with Salmonella Typhimurium SL1344 without productions of siderophores. Through construction and analysis of negative mutant for utilization of human transferrin (hTf)-bound iron, we confirm that the bacterium can directly use human transferrin (hTf)-bound iron without extracellularly intermediated carriers such as siderophores.

• Journal of Korea Water Resources Association
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• v.55 no.8
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• pp.577-588
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• 2022

This study aims to identify the limiting nutrient for algal growth in the Geum River and the significant pollutant sources from the tributaries affecting the water quality and to provide a management alternative for an improvement of water quality. An eight-year of daily data (2013~2020) were collected from the Water Environment Information System (water.nier.go.kr) and Water Resources Management Information System (wamis.go.kr). 14 water quality variables were analyzed at five water quality monitoring stations in the Geum River (WQ1-WQ5). In the Geum River, the water quality variables, especially Chl-a vary greatly in downstream of the river. In the open weir gate operation, TP (total phosphorus) and water temperature greatly influence the growth of algae in downstream of the river. A correlation analysis was used to identify the relationship between variables and investigate the factor affecting algal growth in the Geum River. At the downstream station (WQ5), TP and Temp have shown a strong correlation with Chl-a, indicating they significantly influence the algal bloom. The principal component analysis (PCA) was applied to identify and prioritize the major pollutant sources of the two major tributaries of the river, Gab-cheon and Miho-cheon. PCA identifies three major pollutant sources for Gab-cheon and Miho-cheon, respectively. For Gab-cheon, wastewater treatment plant, urban, and agricultural pollutions pollution are identified as significant pollutant sources. For Miho-cheon, agricultural, urban, and forest land are identified as major pollutant sources. PCA seems to be effective in identifying water pollutant sources for the Geum River and its tributaries in detail and thus can be used to develop water quality management strategies.

• Journal of Life Science
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• v.34 no.6
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• pp.399-407
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• 2024

Angiogenesis is the process by which new blood vessels form from existing blood vessels. This phenomenon occurs during growth, healing, and menstrual cycle changes. Angiogenesis is a complex and multifaceted process that is important for the continued growth of primary tumors, metastasis promotion, the support of metastatic tumors, and cancer progression. Impaired angiogenesis can lead to cancer, autoimmune diseases, rheumatoid arthritis, cardiovascular disease, and delayed wound healing. Currently, there are only a handful of effective antiangiogenic drugs. Recent studies have shown that natural marine products exhibit antiangiogenic effects. In a previous study, we reported that the hexane extract of H. fusiformis (HFH) could inhibit the development of new blood vessels both in vitro and in vivo. The aim of this study was to describe the inhibitory effect of chloroform extracts of H. fusiformis on angiogenesis. To investigate how chloroform extract prevents blood vessel growth, we examined its effects on HUVEC, including cell migration, invasion, and tube formation. In a mouse Matrigel plug assay, H. fusiformis chloroform extract (HFC) also inhibited angiogenesis in vivo. Certain proteins associated with blood vessel growth were reduced after HFC treatment. These proteins include vascular endothelial growth factor (VEGF), mitogen-activated protein kinase (MAPK)/extracellular signal transduction kinase, and serine/threonine kinase 1 (AKT). These studies have shown that the chloroform extract of H. fusiformis can inhibit blood vessel growth both in vitro and in vivo.