• Journal of Life Science
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• v.21 no.2
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• pp.286-291
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• 2011

Hypoxia is a common condition found in a wide range of solid tumors and is often associated with metastasis and poor clinical outcomes. In the present study, we found that HIF-$1{\alpha}$ was induced by cobalt chloride (500 ${\mu}M$) treatment on human lung cancer cells, A549 and H460, for 24 hr. However, cobalt chloride (500 ${\mu}M$) did not affect cell proliferation of A549 and H460 in 48 hr. Cobalt chloride (500 ${\mu}M$) additionally induced epithelial-to-mesenchymal-like transition (EMT) such as reduced E-cadherin expression and increased ${\alpha}$-SMA expression. These results were confirmed by immunofluorecence experiment in H460 cells. E-cadherin was localized on the outer cell membrane. However, when the cells were treated with 500 ${\mu}M$ cobalt chloride for 24 hr, diffuse E-cadherin staining was observed, characteristic of a migratory mesenchymal phenotype. We also found that cobalt chloride induced integrin ${\beta}3$ expression and FAK phosphorylation in human lung cancer cells using western blotting and FACS anlaysis. Our data suggest that integrin ${\beta}3$-induced FAK phosphorylation may be developed into target molecules for blocking tumor metastasis.

• The Journal of Korean Medical History
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• v.26 no.1
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• pp.41-53
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• 2013

In this paper, King Kyung-Jong's strange diseases which had been exacerbated by the Sinim-Sahwa(辛壬士禍) are researched and discussed. The subject will be described mostly based on health and medical records from "The Daily Records of Royal Secretariat of Chosun Dynasty(承政院日記)" and "The Annals of the Choson Dynasty(朝鮮王朝實錄)". Sinim-Sahwa had occurred for two years. It is thought that the beginning of it was 'a controversy on a proclamation of a crown prince, Yeon Ing Goon'. At the first year of Kyung-Jong's ruling, August 21, the No-Ron demanded a king's heir be decided as soon as possible, the king asked Yeon Ing Goon as his successor because of his 'strange diseases'. In October of the same year, the conflict between No-Ron and So-Ron parties reached its peak after a dispute about 'regency from behind the veil for the crown prince' at that time. Kyung-jong added that he had a mysterious and heavy disease and there was little hope to recover from it. Some opposing courtiers emphasized the king was in his good health and there weren't any actual diseases he suffered. But Kyung-Jong stubbornly persisted the diseases he had were so heavy that he couldn't get well readily. In detail, he announced his disease had so deeply rooted in internal organs that he could feel some kind of heat and fire arousal form his heart, then rage and resent soaring. Eventually, on 16th, the No-Ron party followed the king's demand, thus the king's health and illness condition itself was gradually getting off the subject. It seems that Kyung-jong's strange diseases was hwa-byung(火病). His symtoms are similar to the symtoms of hwa-byung. Environment he lived, was enough to cause hwa-byung. as a result, Sinim-Sahwa was the event what his hwa(火) was erupted.

• Asia pacific journal of information systems
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• v.19 no.4
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• pp.149-176
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• 2009

In the recent e-learning environment, avatars are often used to help learners get familiar with the contents, which is ultimately to motivate them to study more. Therefore, it is important to investigate whether avatars have actually the desirable effect on users of e-learning materials. Surprisingly, however, no extensive study has been conducted on this crucial issue Accordingly, main objectives this study are summarized as follows. First, we need to gain better understanding of how much learners' trust towards avatars (termed as "avatar trust") is transferred to learners' trust towards e-learning contents (termed as "contents trust"). Second, we need to investigate how much learners' personal relationships with avatars as well as learning behaviors change depending on avatar types (attractive vs. professional) and contents complexity (easy vs. difficult). As described in the study objectives, in order for us to analyze empirical data more systematically, we classified avatar types into two: "attractive" and "professional;" the contents are categorized as either "easy" or "difficult." Therefore, it is essential for this study to build a prototype e-learning website on which our research purpose can be realized and tested effectively with proper avatar types and e-learning contents. For this purpose, we built a prototype e-learning website, in which avatars are invited from currently working avatar instructors used in real-world e-learning websites, and e-learning contents are adapted from real-world contents about Java programming topic, which have been proved to have shown high quality and reliability. Our research method includes questionnaire survey by inviting a number of valid respondents comprised of office workers who are believed to have high demands for the e-learning contents as well as those who have previous experience with avatar instructors. Respondents were given one of the four e-learning experiment conditions (2 avatar types x 2 contents types) on a random basis. Each experimental e-learning condition is framed to have the same quality but different avatar type and content complexity. Then the respondents are asked to fill out the survey form which has questions about avatar trust, contents trust, personal relationships with avatar, and learning behavior, among others. Regarding the constructs used in research model, we based them rigorously on previous studies. For example, we used six constructs such as behavior to give information (BGI), behavior to obtain information (BOI), need for inclusion wanted, need for control wanted, contents trust, and avatar trust. To measure them, 7-Likert scales were used in the questionnaire. E-learning performance was measured indirectly through two constructs such as BGI and BOI. Six constructs used in the research model were adopted and revised from the FIRO-B model suggested by Schutz. Empirical results are as follows: First, professional avatars are more effective for difficult contents, while attractive avatars were not as effective for easy contents. Second, our study results ascertained that avatar trust transfers to contents trust regardless of avatar types and contents complexity.

• 한국해양학회지
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• v.22 no.2
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• pp.105-118
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• 1987

A series of anchor stations were occupied along the Keum EAstuary during six different periods of tidal and fluvial regimes. The results clearly show that the formation and evolution of the turbidity maximum play an important role in the sedimentary processes in this environment. The turbidity maximum in the Keum Estuary is primarily related to the tidal range at the mouth and is caused by the resuspension of bottom sediments. In this estuary, the turbidity maximum is not a permanent feature and shows semidiurnal, fortnightly and seasonal variations. Repetition of deposition and resuspension of fine sediments occur in response to the variation in current velocity associated with semidiurnal tidal cycles. The core of turbidity maximum shifts landward or seaward accordion to the flood-ebb succession. The turbidity maximum also shows a fortnightly variation in response to the spring-neap cycles. Thus, the turbidity maximum degenerates during neap-tide and regenerates during spring-tide. The freshwater discharge is also an important factor in the formation and destruction of the turbidity maximum. The increase in freshwater discharge in rainy season can create an ebb-dominant current pattern which enhances the seaward transport of suspended sediments, resulting in the shortening of residence time of suspended materials in the estuary. Thus, under this high discharge condition, the turbidity maximum exists only during spring-tide and starts to disappear as the tidal amplitude decreases.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.161-171
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• 2003

The present study evaluated water quality variation, limiting nutrient, and sediment of a shallow eutrophic lake (Lake Ilgam) in the metropolitan area from 2000 to 2002. According to annual mean chl.a ($77.2{\pm}36.6\;{\mu}g/l) and TP ($66.6{\pm}20.5\;{\mu}g/l) concentration and trophic state index (>60), Lake llgam was in very eutrophic status. Both inorganic nitrogen ($NH_3-N$ and $NH_3-N$) and phosphorus (SRP) concentrations in the water column increased during winter and spring, but decreased during summer followed by the phytoplankton development. Evidence for phosphorus and nitrogen as being the potential limiting nutrients for phytoplankton growth was supported by the ratio of DIN/DIP (by mass) (${\sim}$835.8), TSI derivations analysis, and algal growth potential bioassay. Based on the results of TSI derivations, strong nutrient limitation by both N and P occurred from September to November when P content in sediment (114.6 mg P/kg) was relatively low compared with the summer. Sediment contained a large amount of nitrogen (TKN: 4,452${\pm}$283.0mg N/kg dry sediment). Phosphorus content in sediment (TP: 313${\pm}$155 mg P/kg) was relatively low with temporal change. P release rate (0.29${\pm}$0.02 mg $m^{-2}$ $day^{-1}$) was high under the aerobic condition at pH 9. These results indicate that the sediment could play an important role as a source of a limiting nutrient, and temporal change of P content in the sediment is closely related with water quality, especially algal biomass change in Lake llgam.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.172-182
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• 2009

This study was to analyze characteristics based on tolerance and trophic guilds and to determine the level of total mercury in tissues of sentinel species, Zacco platypus at 3 sampling sites of the Mangyeong River in 2007. Total sampled fishes were 26 species and the most dominant species was Zacco temminckii (47%). Fish community analysis was resulted that eveness index and diversity index showed low value at S1. However, diversity index and richness index at other sites showed high. According to various guilds analysis, relative abundance of sensitive species was 70% and 42% at S1 and S2, respectively. While sensitive species were decreased (1%) and tolerant species were increased (60%) at S3. It was mainly carried to the impacts of wastewater treatment plants near the location. Relative abundance of insectivore species was decreased from up (S1) to midstream area (S3). In addition, chemical water quality, based on analyses of BOD, COD, TP, TN, EC, MPN and SS concentration showed similar trends. Qualitative Habitat Evaluation Index (QHEI) was averaged 164, judged as "good" habitat condition. Average concentrations of total [Hg] was 146.9 ${\mu}g$ $kg^{-1}$. In the muscles of total [Hg] was the highest, and then followed by kidney, vertebrae, liver, and gills. According to FDA standards (500 ${\mu}g$ $kg^{-1}$) of Korea, total [Hg] has not affected to the individual fish health.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.161-171
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• 2009

A 'continuous removal of organic matters (CROM) system' using a native freshwater bivalve in Korea Anodonta woordiana, was developed to determine its potential of controlling various sestons in eutrophic lake system, and to evaluate its effect on water quality improvement under consideration of sediment addition as habitat. We designed CROM experiments with four treatments: no mussels and no sediment (W, negative control), no mussels and sediment (WS, positive control), mussels and no sediment (WM), and mussels and sediment (WMS). The experiments were performed at the condition of 18${\sim}$25 L $h^{-1}$ of inflow, mussel density of 486.1 indiv. $m^{-2}$, and temperatures between 15 and $22^{\circ}C$ for 13 consecutive days. Physicochemical and biological parameters were measured at daily (10:00 am) intervals after the mussel addition. Results indicated that mussel stockings without addition of sediment effectively removed sestons (suspended solids and chlorophyll-a) at nearly same level over 80 percentage of the control during the study, while there were no differences in removal activities of sestons between with and without sediment (P>0.5). Therefore, it clearly suggests that CROM system using A. woordiana has a strong potential to control the seston in surface water of eutrophic lake.

• Korean Journal of Ecology and Environment
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• v.41 no.1
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• pp.43-53
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• 2008

This study was conducted to simulate storm hydrographs on a small forested watershed using TOPMODEL, which is a distributed hydrological model. The Myeongseong watershed, which is 58.3 ha in size, was selected to monitor rainfall and runoff data. The Monte Carlo simulation was also used to calibrate parameters of TOPMODEL. Six rainfall-runoff pairs collected at the watershed in the year 1997 were used for parameter calibration, and eight rainfall-runoff pairs collected during the period of $1998\sim1999$ were used for validation effort. The errors of runoff volume ranged from -2.74% to 1.81%, and an average value of model efficiency in terms of runoff volume was 0.92 for the calibration period. The average value of observed peak discharge was $0.324m^3\;s^{-1}$ for six rainfall-runoff pairs, while the prediction value was $0.295m^3\;s^{-1}$. The simulation errors of peak discharge varied according to rainfall characteristics and antecedent condition, within ranges of -27.65% to -1.13%. The model efficiency for the validation period was 0.92. For the validation period, observed peak discharges have an average value of $0.087m^3\;s^{-1}$ and average value of simulated peak discharge was $0.090m^3\;s^{-1}$. Observed and simulated values of time to peak for the calibration period were 18.3 hrs and 11.0 hrs, respectively, and 16.6 hrs and 13.5 hrs, respectively, for the validation period.

• Korean Journal of Ecology and Environment
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• v.47 no.spc
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• pp.10-18
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• 2014

The habitat characteristic of the Gammarus sobaegensis which is one of the Amphipoda kinds has been found inhabiting in the inter mountain stream at Ganseong stream. From the investigation, the main inhabitant area of the G. sobaegensis maintained the water temperature under $10^{\circ}C$ during the spring and autumn season, and the electric conductivity was also maintaining under $40{\mu}Scm^{-1}$. For the precipitation, for this year when the monthly accredited rainfall did not exceed 800 mm, it did not affect maintaining the population of the G. sobaegensis but when the monthly accredited rainfall exceeded 1,000 mm it was found to be working as a unfavorable condition for maintaining the population. The effect especially from this kind of rainfall created the flow of G. sobaegensis as well as the flow of the fallen leaves which are the food resources and affected the population of the G. sobaegensis as a multiple interruption reason. Among the Functional Feeding Groups (FFGs) distribution depending on the use of the food resources the shredders showed up in the ratio of 20% in the site 1~3, and showed a big difference with the site 4~7 as it showed up in the ratio near 10%. Also, after comparing the variation of the individual number among the G. sobaegensis and shredders at the site 1~3 where G. sobaegensis mainly shows up, it showed the same variation pattern except for 2009.

• Korean Journal of Ecology and Environment
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• v.47 no.spc
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• pp.74-82
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• 2014

A perennial plant species of Ranunculaceae, Pulsatilla tongkangensis is a very rare species only found in limestone vegetation of South Korea. It is not only rare but also has great value as a horticultural resource, thus resulting in serious problems of overexploitation and habitat disturbance. For the conservation of the rare species and its development as a resource, the study was conducted with the following three aims: first, to investigate any new geographical distribution of the species; second, to identify the site condition and vegetation structure of its habitat; and third, to compare the ecology of P. tongkangensis in other microhabitats such as rock, slope and ridge area. A new distribution was found in limestone vegetation at Danyang-gun, Chungcheongbuk-do. It was, therefore, confirmed that the distribution of P. tongkangensis exactly coincides with the area of distribution of limestone, indicating a possibility that the species might be a calcicole. 87% of the microhabitats found in rocks. Compared to P. tongkangensis, at ridges or slopes, number of P. tongkangensis plants were few in rocks. It is possibly due to the lack of microhabitats that could settle in rocky areas. Once established on rocks, however, plants grew large enough to flower with higher number of leaves and flowers per plant, resulting in higher flowering rate on rocky areas. Cracks in/between rocks are likely to be safe places for the plants with favorable light conditions, abundant fine particles to root down and reduced competition for resources. Yet, further research is necessary in terms of determining whether the species is indeed a calcicole, whether other limiting factors work in its establishment stage, and genetic diversity exists in the population.