• Journal of Bio-Environment Control
• /
• v.30 no.4
• /
• pp.320-327
• /
• 2021

Freezing damage to fruit trees is frequently occurring due to cold in winter and low temperature in spring to abnormal weather caused by global warming. In particular, the freezing injury of deciduous fruit trees is highly dependent on the developmental stages of the flower buds. And the cold resistance is weakened as the growth progresses, so it is most vulnerable period from flowering to petal fall(post-bloom). Therefore, this study was conducted to analyze the cause of the freezing injury caused by severe low temperature to 'Fuji', which has a late flowering period more than 'Hongro' in April 2020. We investigated freezing injury rate in 'Fuji' and 'Hongro' apple trees damaged by natural low temperature at Boeun-gun, Chungbuk province in Korea. In addition, flower buds in the same developmental stage (tight cluster) were treated artificially low temperature to investigate the injury rate for accurate comparative analysis between varieties, and to analyze the soluble sugar and hormone contents in the flower buds. As a result of survey in natural low temperature, 'Fuji' had a higher injury rate than 'Hongro' in both orchards, and in particular, B orchard 'Fuji' had the highest injury rate of 60.5%. Also there were significantly difference in the freezing injury rate between 'Fuji' and 'Hongro' in artificially low temperature treatments. As a result of analyzing the soluble sugar contents in 'Hongro' was higher than 'Fuji'. Also ABA, IAA and SA contents were more increased in the damaged tissue than in the normal flower buds by low temperature treatments. Consequently, it was assumed that the freezing injury was closely related to soluble sugar contents in the flower buds. In particular, the freezing injury rate was negatively correlated with the sorbitol contents.

• Journal of Korea Water Resources Association
• /
• v.51 no.12
• /
• pp.1195-1205
• /
• 2018

In the study, the water shortage of Boryeong Dam watershed ($163.6km^2$) was evaluated under future climate change scenario. The Soil and Water Assessment Tool (SWAT) was used considering future dam release derived from multiple linear regression (MLR) analysis. The SWAT was calibrated and verified by using daily observed dam inflow and storage for 12 years (2005 to 2016) with average Nash-Sutcliffe efficiency of 0.59 and 0.91 respectively. The monthly dam release by 12 years MLR showed coefficient of determination ($R^2$) of above 0.57. Among the 27 RCP 4.5 scenarios and 26 RCP 8.5 scenarios of GCM (General Circulation Model), the RCP 8.5 BCC-CSM1-1-M scenario was selected as future extreme drought scenario by analyzing SPI severity, duration, and the longest dry period. The scenario showed -23.6% change of yearly dam storage, and big changes of -34.0% and -24.1% for spring and winter dam storage during 2037~2047 period comparing with 2007~2016 period. Based on Runs theory of analyzing severity and magnitude, the future frequency of 5 to 10 years increased from 3 in 2007~2016 to 5 in 2037~2046 period. When considering the future shortened water shortage return period and the big decreases of winter and spring dam storage, a new dam operation rule from autumn is necessary for future possible water shortage condition.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.24 no.3
• /
• pp.375-388
• /
• 2019

Accurate evaluation of sea-to-air $CO_2$ flux and its variability is crucial information to the understanding of global carbon cycle and the prediction of atmospheric $CO_2$ concentration. $fCO_2$ observations are sparse in space and time in the East Sea. In this study, we derived high resolution time series of surface $fCO_2$ values in the southwest East Sea, by feeding sea surface temperature (SST), salinity (SSS), chlorophyll-a (CHL), and mixed layer depth (MLD) values, from either satellite-observations or numerical model outputs, to three machine learning models. The root mean square error of the best performing model, a Random Forest (RF) model, was $7.1{\mu}atm$. Important parameters in predicting $fCO_2$ in the RF model were SST and SSS along with time information; CHL and MLD were much less important than the other parameters. The net $CO_2$ flux in the southwest East Sea, calculated from the $fCO_2$ predicted by the RF model, was $-0.76{\pm}1.15mol\;m^{-2}yr^{-1}$, close to the lower bound of the previous estimates in the range of $-0.66{\sim}-2.47mol\;m^{-2}yr^{-1}$. The time series of $fCO_2$ predicted by the RF model showed a significant variation even in a short time interval of a week. For accurate evaluation of the $CO_2$ flux in the Ulleung Basin, it is necessary to conduct high resolution in situ observations in spring when $fCO_2$ changes rapidly.

• Journal of the Korean Institute of Traditional Landscape Architecture
• /
• v.37 no.2
• /
• pp.66-73
• /
• 2019

The Royal Tomb of the Joseon Dynasty, which was listed as a UNESCO World Heritage site in 2009, is a cultural resource recognized for its 'outstanding universal value' around the world. The royal tomb of Joseon has been managed with an emphasis on the preservation of cultural assets since it was designated as a historical site in the 1970s, but it has received many visitors as a valuable historical and cultural resource and haven that connects the past and the present in today's bustling city. In order to investigate and analyze the current status of pavements in the royal palace in terms of quality and quantity, and to suggest the direction of improvement, this study conducted a complete survey of 53 royal palace viewing roads in 18 regions, and the results are as follows. First of all, problems are found in both the early Masato pavement of the creation, which was introduced with an emphasis on the preservation and protection of cultural assets, and the hardening pavement(KAP), which began to be used in the 1990s for the convenience of maintenance. In other words, the Masato pavement used to create a more environmentally friendly atmosphere of the Joseon royal tombs is showing a high percentage of use, but it lacks support for walking activities, such as the slippage of the pavement and water pooling during the rainy season or during the ice season. Also, hardening pavement introduced for convenience of maintenance, such as the movement of repair vehicles, is not functioning properly as it is damaged by physical deformation after construction. In addition, in awe zones such as parking lots, although the first image of the Joseon royal tombs is determined, the formation of the functional landscape centered on the carriageway does not harmonize with the traditional landscape, and, because of its lack of walking and environment-friendly features, there is a need for improvement, such as the experimental introduction of relevant pavement materials developed afterwards and continuous monitoring.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.38 no.4
• /
• pp.310-319
• /
• 2018

The southern type grasses announced for the test were the Bermudagrass cultivars (Giant, Cheyenne, Mohawk, Panchero Frio, Common and Tifton 85) and the Bahiagrass cultivars (TifQuik, Tifton 9), and the changes in the productivity and nutrient content were surveyed in Jeju area (450m altitude). The different cultivars were sowed by broadcasting or drill seeding method, and Tifton 85 was transplanted from sprigs. The fresh and dry matter yield showed varying significant differences for different cultivars (p<0.05). The fresh yields of Tifton 85, TifQuik and Tifton 9 were excellent, compared to the other cultivars, and for the dry matter yield, Tifton 85 and Tifton 9 were excellent when compared to the other cultivars. Crude protein content showed significant differences among different cultivars (p<0.05). Cheyenne, Mohawk, Panchero Frio, and Common showed differences in the crude protein content by sowing method and harvest time (p<0.05). The different cultivars showed differences in the crude fiber content (p<0.05), and Tifton 9 registered significantly high content and Mohawk and Tifton 85 showed significant crude fiber content by harvest time (p<0.05). According to these results, the southern type grass cultivars showed big differences in the regenerative capacity against damage from frost, productivity, and nutrient content, so they need to be chosen according to the purposes, and to increase their usage, their evaluation needs to be conducted at various altitudes.

• Korean Journal of Ecology and Environment
• /
• v.52 no.3
• /
• pp.210-220
• /
• 2019

Population growth and the increase of energy consumption due to civilization caused global warming. Temperature on the Earth rose about $0.7^{\circ}C$ for the last 100 years, the rate is accelerated since 2000. Temperature is a factor, which determines physiological action, growth and development, survival, etc. of the plant together with light intensity and precipitation. Therefore, it is expected that global warming would affect broadly geographic distribution of the plant as well as structure and function ecosystem. In order to understand the effect of global warming on the ecosystem, a study about the effect of temperature rise on germination and growth in the plant is required necessarily. This study was carried out to investigate the effects of experimental warming on the germination and growth of two oak species(Quercus mongolica and Q. serrata) in temperature gradient chamber(TGC). This study was conducted in control, medium warming treatment($+1.7^{\circ}C$; Tm), and high warming treatment ($+3.2^{\circ}C$; Th) conditions. The final germination percentage, mean germination time and germination rate of two oak species increased by the warming treatment, and the increase in Q. serrata was higher than that in Q. mongolica. Root collar diameter, seedling height, leaf dry weight, stem dry weight, root dry weight, and total biomass were the highest in Tm treatment. Butthey were not significantly different in the Th treatment. In the Th treatment, Q. serrata had significantly higher H/D ratio, S/R ratio, and low root mass ratio (RMR) compared with control plot. Q. mongolica had lower RMR and higher S/R ratio in the Tm and Th treatments compared with control plot. Therefore, growth of Q. mongolica are expected to be more vulnerable to warming than that of Q. serrata. The main findings of this study, species-specific responses to experimental warming, could be applied to predict ecosystem changes from global warming. From the result of this study, we could deduce that temperature rise would increase germination of Q. serrata and Q. mongolica and consequently contribute to increase establishment rate in the early growth stage of the plants. But we have to consider diverse variables to understand properly the effects that global warming influences germination in natural condition. Treatment of global warming in the medium level increased the growth and the biomass of both Q. serrata and Q. mongolica. But the result of treatment in the high level showed different aspects. In particular, Q. mongolica, which grows in cooler zones of higher elevation on mountains or northward in latitude, responded more sensitively. Synthesized the results mentioned above, continuous global warming would function in stable establishment of both plants unfavorably. Compared the responses of both sample plants on temperature rise, Q. serrata increased germination rate more than Q. mongolica and Q. mongolica responded more sensitively than Q. serrata in biomass allocation with the increase of temperature. It was estimated that these results would due to a difference of microclimate originated from the spatial distribution of both plants.

• Korean Journal of Environment and Ecology
• /
• v.33 no.5
• /
• pp.525-538
• /
• 2019

The purpose of this study was to analyze the habitat status and species diversity of benthic diatoms and estimate the applicability of TDI (Trophic Diatom Index) to obtain the basic data for the identification and management of created wetlands in the Nakdong River. We observed a total of 38 families and 173 species of benthic diatom during the survey period, and spring and autumn showed a similar number of species of 156 and 154, respectively. The result of the SOM (Self-Organizing Map) analysis showed that the distribution of benthic diatom was sensitive to environmental factors such as nutrient concentration and rainfall in each wetland. The cluster 1 was characterized by the survey sites of autumn mostly and consisted of points of high TDI, although the nutrients such as total phosphorus and total nitrogen were low, and the species number and abundance of diatoms were low. Conversely, cluster 4 was characterized by the survey sites of spring mostly and consisted of points of low TDI, even though total nitrogen was high. Considering that most of the created wetlands had the reduced inflow and outflow, the increased flow rate in the summer lowers nutrient values in autumn, and the species number and abundance of benthic diatom decreases due to the increase of turbidity, which reduces the light penetrations to the substrates. On the contrary, the TDI value is low in spring because the low water level causes insufficient substrate surface to the benthic diatoms, and it is too early for the establishment and development of saprophilous species. Although various studies have used TDI as an indicator for evaluating the habitat environment and water quality, it is not a good evaluation indicator in this study since the nutrient concentration in the wetlands mostly high as they have a low flow rate and are close to the stagnant area. Nevertheless, additional periodic surveys that comprehensively reflect the fact that the summer rainfall and inflow/outflow regulating function might affect the species diversity and distribution of benthic diatoms are necessary.

• Korean Journal of Remote Sensing
• /
• v.37 no.3
• /
• pp.657-664
• /
• 2021

In this study, we investigated the relationships between the air quality (PM_2.5, PM₁₀, O₃) concentrations and local geographical characteristics (terrain heights, building area ratios, population density in 9 km × 9 km gridded subareas) in the Seoul metropolitan area. To analyze the terrain heights and building area ratios, we used the geographic information system data provided by the NGII (National Geographic Information Institute). Also, we used the administrative districts and population provided by KOSIS (Korean Statistical Information Service) to estimate population densities. We analyzed the PM_2.5, PM₁₀, and O₃ concentrations measured at the 146 AQMSs (air quality monitoring system) within the Seoul metropolitan area. The analysis period is from January 2010 to December 2020, and the monthly concentrations were calculated by averaging the hourly concentrations. The terrain is high in the northern and eastern parts of Gyeonggi-do and low near the west coastline. The distributions of building area ratios and population densities were similar to each other. During the analysis period, the monthly PM_2.5 and PM₁₀ concentrations at 146 AQMSs were high from January to March. The O₃ concentrations were high from April to June. The population densities were negatively correlated with PM_2.5, PM₁₀, and O₃ concentrations (weakly with PM_2.5 and PM₁₀ but strongly with O₃). On the other hand, the AQMS heights showed no significant correlation with the pollutant concentrations, implying that further studies on the relationship between terrain heights and pollutant concentrations should be accompanied.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.41 no.1
• /
• pp.23-28
• /
• 2021

This experiment was conducted to compare the seed productivity of Spring sown Italian ryegrass(Lolium multiflorum Lam.) depending on the seeding rates(20kg/ha, 30kg/ha, 40kg/ha) in Gangwon region. The experiment was a randomized block design with three replications. The test plots were located in alpine areas of about 600 m above sea level in Gangwon province. The tested Italian ryegrass variety was 'Greencall' developed by the National Institute of Animal Science, RDA. Italian Ryegrass was sown on March 26, 2020, and the seed harvesting was on the 60th day(2 July) from heading date. The heading date was May 8 with no difference, There were no significant differences in the agronomic characteristics including plant height. 30kg/ha seed rate was the highest at 146.8 seed/spike and 40kg/ha seed rate was the lowest at 114.7 seed/spike for the number of seeds per spike. The number of spikes per unit area was the highest in 40kg/ha at 886/㎡ and the lowest in 20kg/ha at 750/㎡. The yield of seed and straw was the highest in 40kg/ha at 1,288kg/ha and 2,970kg/ha respectively, but there was no difference. From the above results, the production of Italian ryegrass seeds through spring sowing in the Gangwon region is not much than autumn seeding, requiring the input of various technologies to increase productivity in the future, and it is desirable to determine the production cost through economic analysis was evaluated.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.41 no.1
• /
• pp.16-22
• /
• 2021

This experiment was conducted to study on the growth characteristics and seed productivity of Italian ryegrass (Lolium multiflorum Lam., IRG) planted in the Spring in Gangwon Highland according to the seeding distance (20, 30 and 40 cm). The field was located in highland around 600 m above sea level. The experimental design was randomized block design with three replication and the tested IRG variety was 'Greencall' developed by National Institute of Animal Science (NIAS). IRG was sown on March 26, 2020, and harvested on July 2. The plant height was the shortest at 80.5 cm in the 40 cm seeding distance plot (P<0.05), and there was no significant difference between the 20 and 30 cm seeding distance. The number of spike per square meter (㎡) was significantly higher in the 20 cm seeding distance plot than that of 40 cm (937 vs. 571). The dry matter (DM) content of seed and straw after harvesting was 49.70 and 33.36 % on average, and there was no significant difference between treatments (P>005). However, there was a significant difference in the fresh and DM yield of seeds and straw (P<0.05). DM yield of seeds was significantly higher in 20 cm distance than that of 40 cm, and the yield of straw was the same trend. On the other hand, there was no significant difference in DM yield between 20 cm and 30 cm and also in the feed value of straw after seed harvesting among seeding distance. The average CP, ADF, NDF, and TDN contents were 6.91, 36.76, 61.75 and 59.86%, respectively, and the RFV value was 91. Considering the above results, the production of Italian ryegrass seeds sown in the spring in the highlands of the Gangwon is lower than that of autumn sowing, but it is judged that it needs to be reviewed in case it is unavoidable. In the future, there should be an economic analysis and the development of technology that can increase production.