• Korean Journal of Ecology and Environment
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• v.34 no.3 s.95
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• pp.153-165
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• 2001

We evaluated the health condition of Pyong-Chang river, the tributary of Han- River, using the Index of Biological Integrity (IBI) and Qualitative Habitat Evaluation Index (QHEI) during September 1999${\sim}$August 2000. The annual mean of IBI,　which was estimated using eleven metrics, was 49 (range: $45{\sim}51$) and the mean of QHEI, which was estimated using seven parameters, was 88 (range: $76{\sim}94$) during　the study. The river health, based on the IBI criteria of Karr (1981), ranged from "excellent" to "good" conditions, while based on the habitat criteria of Plafkin et al. (1989), it ranged from "pristine" (comparable to reference) to "supporting" conditions. Values of IBI showed slight differences between upstream and downstream sites and QHEI values varied weakly depending on characteristics of variables. Regression analyses showed that annual values of QHEI had no functional relations with stream order (p = 1.82; n = 8) but showed some decreases near slight point-sources. This result indicates that conditions of physical habitat did not change highly with increases of the stream order. According to analyses of feed guilds, relative abundance of insectivores, omnivores and carnivores was 85.1%, 3.5% 0.3%, respectively. Also, relative abundance of sensitive and tolerant species was 75% and 4.6%, respectively, while exotic and morphological anomalies were not found in the river. These outcomes indicate that health condition of fish, based on the trophic conditions of U.S. EPA (1993), was excellent in the river. Regression analyses of IBI values against the QHEI showed that the variation of habitat conditions accounted 57% for the variation of the Index of Biological Integrity (p<0.05; $R^2\;=\;0.57$; n = 7).Overall data of IBI and QHEI suggest that the river health in the present is in optimal conditions but may be degradated by acceleration of chemical inputs and physical-habitat disturbance.

• Korean Journal of Remote Sensing
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• v.30 no.2
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• pp.241-249
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• 2014

The continuous observations for atmospheric aerosol were carried out during 3 years (2009-2011) by using a multi-wavelength Raman lidar at the Gwangju Institute of Science and Technology (GIST), Korea ($35.11^{\circ}N$, $126.54^{\circ}E$). The particle depolarization ratios were retrieved from the observations in order to distinguish the Asian dust layer. The vertical information of Asian dust layers were used as input parameter for the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model for analysis of its backward trajectories. The source regions and transport pathways of the Asian dust layer were identified. The most frequent source region of Asian dust in Korea was Gobi desert during observation period in this study. The statistical analysis on the particle depolarization ratio of Asian dust was conducted according to their transport route in order to retrieve the variation of optical properties of Asian dust during long-range transport. The transport routes were classified into the Asian dust which was transported to observation site directly from the source regions, and the Asian dust which was passed over pollution regions of China. The particle depolarization ratios of Asian dust which were transported via industrial regions of China was ranged 0.07-0.1, whereas, the particle depolarization ratio of Asian dust which was transported directly from the source regions to observation site were comparably higher and ranged 0.11-0.15. It is considered that the pure Asian dust particle from source regions were mixed with pollution particles, which is likely to spherical particle, during transportation so that the values of particle depolarization of Asian dust mixed with pollution was decreased.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.221-232
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• 2016

Models to estimate solar radiation have been used because solar radiation is measured at a smaller number of weather stations than other variables including temperature and rainfall. For example, solar radiation has been estimated using the Angstrom-Prescott (AP) model that depends on two coefficients obtained empirically at a specific site ($AP_{Choi}$) or for a climate zone ($AP_{Frere}$). The objective of this study was to identify the coefficients of the AP model for reliable estimation of solar radiation under a wide range of spatial and temporal conditions. A global optimization was performed for a range of AP coefficients to identify the values of $AP_{max}$ that resulted in the greatest degree of agreement at each of 20 sites for a given month during 30 years. The degree of agreement was assessed using the value of Concordance Correlation Coefficient (CCC). When $AP_{Frere}$ was used to estimate solar radiation, the values of CCC were relatively high for conditions under which crop growth simulation would be performed, e.g., at rural sites during summer. The statistics for $AP_{Frere}$ were greater than those for $AP_{Choi}$ although $AP_{Frere}$ had the smaller statistics than $AP_{max}$ did. The variation of CCC values was small over a wide range of AP coefficients when those statistics were summarized by site. $AP_{Frere}$ was included in each range of AP coefficients that resulted in reasonable accuracy of solar radiation estimates by site, year, and month. These results suggested that $AP_{Frere}$ would be useful to provide estimates of solar radiation as an input to crop models in Korea. Further studies would be merited to examine feasibility of using $AP_{Frere}$ to obtain gridded estimates of solar radiation at a high spatial resolution under a complex terrain in Korea.

• Korean Journal of Ecology and Environment
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• v.48 no.3
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• pp.176-187
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• 2015

In this study, we hypothesized that the size of wintering crane population would change due to the climate factors. We assumed that wintering population size would differ by climate values in January, which is the coldest period in year. Especially, White-naped cranes were able to choose wintering site between Cheorwon and other alternative place where snow coverage had low influence, differing from Red crowned cranes. For this reason, we predicted the population size of White-naped cranes would fluctuate according to the extent of snow coverage in Cheorwon. Therefore we used snow coverage data based on MODIS and climate data from KMA (Korea Meteorological Administration) that are generally used. We analyzed the crane's population size in Cheorwon in January from 2002 to 2014. The temperature in the Cheorwon increased from 2002 to wintering period in 2007~ 2008 and went down, showing the lowest temperature in 2011~ 2012. With this phenomenon, warmth index showed the similar pattern with temperature. Amount of newly accumulated snow (the amount of snow that fallen from 0:01 am to 11:29 pm in a day) was low after 2002, but rapidly increased in 2010~ 2011 and 2011~ 2012. The area of snow coverage rapidly declined from 2002 to 2005~ 2006 but suddenly expanded in wintering period in 2009~ 2010 and 2010~ 2011. Wintering population size of the White-naped cranes decreased as snow coverage area increased in January and the highest correlation was found between them, compared to the other climatic factors. However, the number of individuals of Red crowned cranes had little relationship with general climate factors including snow cover range. Therefore it seems that population size of the Red crowned crane varied by factors related with habitat selection such as secure roosting site and area of foraging place, not by climatic factors. In multiple regression analysis, wintering population of White-naped cranes showed significant relationship with logarithmic value of snow cover range and its period. Therefore, it suggests that the population size of the White-naped crane was affected by snow cover range n wintering period and this was because it was hard for them to find out rice grains which are their main food items, buried in snow cover. The population size variation in White-naped cranes was caused by some individuals which left Cheorwon for Izumi where snow cover had little influence on them. The wintering population in Izumi and Cheorwon had negative correlation, implying they were mutually related.

• Journal of Bio-Environment Control
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• v.9 no.3
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• pp.171-178
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• 2000

Gross photosynthetic rats of leaves of hydroponically grown cucumber plants(Cucumis sativus L. cv. Guwoosalichungjang) were measured under various conditions of photosynthetic photon flux(PPF), ambient $CO_2$ concentration, air temperature and leaf nitrogen contents. Light compensation point of leaf photosynthesis appeared to be in the range of 10~20$\mu$mol.m$^{-2}$ .s$^{-1}$ and light saturation point be above 1000$\mu$mol.m$^{-2}$ .s$^{-1}$ . Gross photosynthetic rates increased persistently and asymptotically as air temperature rose from 12$^{\circ}C$ to 32$^{\circ}C$. However, there were only small differences in gross photosynthetic rates in the range of 24-32$^{\circ}C$, so that the range seemed to be optimal for photosynthesis of cucumber plants at the condition of $CO_2$ concentration of 400$\mu$mol.mol$^{-1}$ and PPF of around 400$\mu$mol.m$^{-2}$ .s$^{-1}$ . $CO_2$ compensation point of leaf photosynthesis appeared to be in the range of 20-40$\mu$mol.mol$^{-1}$ and $CO_2$ saturation point be above 1200$\mu$mol.mol$^{-1}$ . Gross photosynthetic rates increased sigmoidally as leaf nitrogen content increased. These environmental factors interacted synergistically to enhance gross photosynthetic rate, so that the rate increased multiplicatively s level of one factor increased progressively with higher levels of he other factors. Mathematical models wer developed to estimate the gross photosynthetic rate in accordance with the variations of these environmental factors. These modes can be used not only to explain he variation of growth or yield of cucumber plants under different environmental conditions but also as building blocks of plant growth model or expert system of cucumber plants.

• Korean Journal of Environmental Agriculture
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• v.31 no.3
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• pp.248-254
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• 2012

BACKGROUND: In order to elucidate residual characteristics of difenoconazole and thiamethoxam by treatment to sweet persimmons for one year and to generate the data for the maximum residue limit (MRL) establishment for those pesticides in or on sweet persimmon. METHODS AND RESULTS: Systemic fungicide difenoconazole WP (10% a.i.) and systemic insecticide thiamethoxam WG (10% a.i.) were sprayed onto 12~25-years-old sweet persimmons according to its preharvest interval (PHI), respectively, and then fresh sweet persimmons were harvested at 0, 1, 3, 7, 14, 21 days after treatment from pesticide-sprayed plots at each 3 sites. The analytical methods were evaluated to limit of quantification, linearity, specificity, reproducibility and recoveries. The crop samples were extracted with acetone and performed dichloromethane partition process. The extracted samples of difenoconazole were analyzed by GC-ECD and the thiamethoxam extracted samples were analyzed by HPLC with good sensitivity and selectivity of the method. The average recoveries of difenoconazole ranged from 87.5 to 99.5% with the percentage of coefficient variation in the range 4.1~7.6% at three different spiking levels(0.02, 0.2 and 2.0 mg/kg). And the average recoveries of thiamethoxam and clothianidin ranged from 88.8 to 98.9% and 83.2 to 96.6% with the percentage of coefficient variation in the range 3.6~5.0% and 3.8~9.4% at three different spiking levels(0.02, 0.2 and 2.0 mg/kg), respectively. The residue amounts ranges of difenoconazole were 0.2~0.56 mg/kg and the residue amount was decreased below the MRL level, 1.0 mg/kg, after 1 day harvest. The residue amounts ranges of thiamethoxam were 0.08~0.28 mg/kg and the residue amount was decreased below the MRL level, 0.5 mg/kg, after 1 day harvest. And the residue amount of clothianidin was below then 0.03 mg/kg for only one test site of 14 and 28 day samples. CONCLUSION: As a result, the residual amounts of difenoconazole and thiamethoxam were not exceeded the MRL of established criteria for sweet persimmon. The biological half-lives of difenoconazole and thiamethoxam were 13.6, 19.4, 16.3 and 10.0, 15.3, 14.0 days at each three test sites, respectively.

• Economic and Environmental Geology
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• v.36 no.6
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• pp.481-490
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• 2003

The objectives of this study are (1) to determine the extent and degree of As contamination of the water and sediments influenced by mining activity of the abandoned Au-Ag mines, (2) to examine As speciation In contaminated water, (3) to monitor variation of As contamination in water system throughout the dry and wet seasons, and (4) to investigate the As chemical form in the sediments through the sequential extraction analyses. Natural water(mine water, surface water and groundwater) and sediments were collected in six abandoned Au-Ag mine(Au-bearing quartz veins) areas. The contamination level of As in mine water of the Dongil(524${\mu}m$/L) is more higher than the tolerance level(500 ${\mu}m$/L) for waste water of mine area in Korea. Elevated levels of As in stream water were also found in the Dongil(range of 63.7∼117.6 ${\mu}m$/L.) and Gubong(range of 56.1∼62.9 ${\mu}m$/L) mine areas. Arsenic contamination levels in groundwater used by drinking water were more significant in the Dongil(11.3∼63.5 ${\mu}m$/L), Okdong(0.2∼68.9 ${\mu}m$/L) and Gubong(2.0∼101.0${\mu}m$/L) mine areas. Arsenate[As(V), $H_2AsO_4^-$] is more dominant than arsenite[As(III), $H_3AsO_3$] in water system of the most mine areas. The concentration ratios of As(III) to As(total), however, extend to the 95% in stream water of the Okdong mine area and 70∼82% in groundwater of the Okdong and Dongjung mine areas. As a study of seasonal variation in the water system, relatively high levels of As from the dongil mine area were found in April rather than in September. Sequential extraction analysis showed that As was predominantly present as coprecipitated with Fe hydroxides from sediment samples of the Dongjung and Gubong mine(35.9∼40.5%), which indicates its possibility of re-extraction and inducing elevated contamination of As in the reductive condition. In sediments from the Dongil, Okdong and Hwachon mine area, high percentage(55.2∼83.4%) of As sulfide form was found.

• Korean Journal of Environment and Ecology
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• v.31 no.3
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• pp.279-286
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• 2017

We investigated growth response and variation of ecological niche breadth of Hibiscus hamabo according to light, moisture and nutrient when global warming is proceeded by elevated $CO_2$ concentration and temperature. H. hamabo was cultivated in experimental condition in the greenhouse that are divided by control(ambient condition) and treatment(elevated $CO_2$ concentration and temperature). Light, moisture and nutrient gradients were treated within the control and the treatment. Although H. hamabo prefers higher light intensity(up to L3) to lowers', Hamabo mallow doesn't like excessive light intensity($787{\pm}77.76{\mu}mol\;m^{-2}s^{-1}$). Also, H. hamabo was difficult to grow in absent nutrient(0%) and excessive nutrient(20%). However, there was no trend with moisture gradients. The death rate of H. hamabo in the treatment was higher in all gradients except for the highest light intensity condition than control. It means that range of tolerance about light is narrowed when concentration of $CO_2$ gas and temperature is elevated. There was no trend of death rate according to moisture gradient, comparing between control and treatment. The death rate in all nutrient gradients within the treatment is lower than the controls'. It means that range of tolerance about nutrient is widened. The ecological niche breadth of H. hamabo in the treatment was narrower as 30.1% in light gradients but wider as 8.6% in moisture gradients and 30% in nutrient gradients than in the control. In the conclusion, when global warming is proceeded by elevated $CO_2$ concentration and temperature, growth of H. hamabo would be restricted by light intensity.

• Korean Journal of Heritage: History & Science
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• v.53 no.1
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• pp.52-63
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• 2020

This study was conducted in order to evaluate the characteristics of air temperature fluctuation inside the Daegeumgul, Ondaldonggul, and Seongnyugul Caves, which are the most representative limestone caves in Korea, and also to assess the effects of air temperature on cave temperature. Temperature was measured hourly at three sites in Daegeumgul, Ondaldonggul, and Seongnyugul Caves from April 13 to June 25, 2019. Additionally, air temperature data for the areas around the caves was provided by the Meteorological Administration. Using this collected data, the basic statistical measure of fluctuation characteristics over time was ascertained, and time series analyses were performed. Wide variation of temperature was exhibited in the order of the cave entrance, the cave water inflow point, and the midpoint. Cave temperature was observed to increase gradually during the study period. There was a vast range in temperature at the Daegeumgul station located approximately 150 m outside the cave, but it remained nearly constant beyond the midpoint. Although the effect of air temperature was not significant due to the influence of visitors, the effect of air temperature on cave temperature gradually decreased from the entrance to the interior. At Ondaldonggul, there was a wide range in temperature recorded at the entrance due to the influence of air temperature, but it stayed almost constant in the interior. However, at the site where cave water flows into the cave, temperature was influenced by the cave water temperature. At Seongnyugul, there was a distinct fluctuation in temperature recorded at the cave entrance, while the middle of the cave remained nearly constant. Temperature fluctuated due to the air temperature at the entrance, while at the middle of the cave, measurements were expected to be affected to a greater extent by the lake water temperature than by the air temperature. However, this pattern was not observed. According to the time series analysis results, in all caves, fluctuations of air temperature affected cave temperature after approximately one hour. Cave size and structure, water presence, the entrance's size and shape, air flow, and visitor patterns can all influence cave temperature. Therefore, consideration of these factors is very important in the pursuit to clearly understand cave temperature characteristics.

• The Korean Journal of Mycology
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• v.41 no.2
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• pp.57-66
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• 2013

The mushrooms collected at seven areas of Mt. Chiak in 2002 and 2003 were classified to analyse the distribution and species diversity. Frequency (number of mushroom : N), number of species (S), relative species density (RSD), similarity index (C), richness index (R1), variety index (V1), evenness index (E2), and dominance index(D1) were investigated. Total N and S was 143 and 84, respectively. The RSD was 0.179 ~ 0.226 of the 7 areas. The yearly C of the total area (0.213) was 8.2%. more higher than the average C of 7 areas (0.131). The order in the coefficient of variation (CV) of the indicator for 7 areas was N (10.5%) > D1 (9.2%) > V1 (8.9%) > S (8.5%) > R1 (7.4%) > E2 (2.2%). The average R1 of the 7 areas was 5.36 with the range from 4.85 to 6.01, and 16.72 for the total area. The average V1 of the 7 areas was 16.24 with the range from 14.44 to 18.66, and 68.82 for the total area. The average E2 of the 7 areas was 0.95 with the range from 0.926 to 0.982, and 0.819 for the total area. The average D1 of the 7 areas was 0.071 with the range from 0.055 to 0.073, and 0.081 for the total area. The correlation between N and 5 kinds of diversity indicator (S, R1, V1, E2, D) was not statistically significant, but the correlation between R1, E2 and D1 was statistically significant each other.