• Korean Journal of Environment and Ecology
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• v.31 no.6
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• pp.549-556
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• 2017

The purpose of this study was to investigate the change of spatial distribution of Korean fir (Abies koreana E. H. Wilson) in Mt. Hallasan for the past 10 years. We examined the distribution and crown density between 2006 and 2015 and analyzed the elevation, direction, and regional characteristics. The total area of Korean fir was 626.0ha in 2015, which declined by 112.3ha accounting for 15.2% for the past 10 years compared to 738.3ha in 2006. For the past 10 years, the area of moderately dense Korean fir with the crown density of 41% to 70% decreased by 72.6ha while the area of dense Korean fir with the crown density of 71% or more deceased by 21.3ha. The area with an elevation between 1,510m and 1,600m showed the largest change, accounting for 32.6% of the total declining area. Regarding the distribution by the direction, the area in the southeastern direction decreased by 23.4ha while the area in the southeast and northeast centered on the eastern direction decreased by 62.3ha, which accounted for 55.5% of the total area. Regarding the change of the distribution of Korean fir forest area by the region, the decrease of the area from the Jindallaebat to the top of the mountain was the largest at 84.6ha, or 71.8% of the total decreased area. The Yeongshil Trail area decreased by 25.3ha or 21.5% of the total while the Keundurewat area decreased by 8.0ha or 6.8%. On the contrary, the Bangaeoreum area increased by 5.6ha. The results indicate the large decrease of area of Korean fir forest centered on a particular location of Mt. Hallasan. Considering the changes according to the elevation, direction, and regional characteristics, it can be attributed to increasing frequency of abnormal climates such as typhoons and droughts.

• Journal of The Korean Society of Grassland and Forage Science
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• v.26 no.3
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• pp.159-170
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• 2006

This study was conducted to investigate the effects of two dry matter levels of liquid swine manure on dry matter yield and nutritive value of Italian ryegrass, rye and oats, and the chemical characteristics of soil in Jeju. This experiment tested in split plot design. Three forage crops (Italian ryegrass, rye and oats) were the main plot and four fertilizers (no fertilizer=T0, chemical fertilizer=T1, liquid swine manure with DM 2.7%=T2 and liquid swine manure with DM 5.9 %=T3) were the sub plots. Yield and nutrient contents of forage crops and soil properties were determined. Application of liquid swine manure containing 5.9% dry matter resulted in highest DM yield in all three forage crops species compared with the other treatments (p<0.01). Crude protein content(%) and crude protein yield(kg/ha) of forage crops were highest in rye compared with the other forage crops species(p<0.01). K and Mg contents of soil were higher(p<0.01) in rye than in the other species while Na contents was higher(p<0.01) in Italian ryegrass than others. Mg content of soil appeared higher in rye than in the others and higher(p<0.05) in forage crops applied with liquid manure containing 2.7% DM compared with the other species. $NO_3-N$ contents in soil was lower in rye than the other species and higher in species with chemical fertilizer. These findings indicate that most of liquid swine manure produced on local pig farms containing low levels of dry matter and other nutrients suggest a low efficiency of its use as a fertilizer. The liquid swine manure is recommended as a fertilizer for rye production in winter, compared with Italian ryegrass or oat.

• Economic and Environmental Geology
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• v.44 no.2
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• pp.135-152
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• 2011

Nitrate concentrations in springs at the southern slope of Jeju Island were predicted using multiple linear regression (MLR) of spatial variables including hydrogeological parameters and land use characteristics. Springs showed wide range of nitrate concentrations from <0.02 to 86 mg/L with a mean of 20 mg/L. Spatial variables were generated for the circular buffer when the optimal buffer radius was assigned as 400 m. Selected regression models were tested using the p values and Durbin-Watson statistics. Explanatory variables were selected using the adjusted $R^2$, Cp (total squared error) and AIC (Akaike's Information Criterion), and significance. In addition, mutual linear relations between variables were also considered. Small portion of springs, usually <10% of total samples, were identified as outliers indicating limitations of MLR using circular buffers. Adjusted $R^2$ of the proposed models was improved from 0.75 to 0.87 when outliers were eliminated. In particular, the areal proportion of natural area had the greatest influence on the nitrate concentrations in springs. Among anthropogenic land uses, the influence of nitrate contamination is diminishing in the following order of orchard, residential area, and dry farmland. It is apparent quality of springs in the study area is likely to be controlled by land uses instead of hydrogeological parameters. Most of all, it is worth highlighting that the contamination susceptibility of springs is highly sensitive to nearby land uses, in particular, orchard.

• Korean Journal of Environment and Ecology
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• v.23 no.6
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• pp.528-534
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• 2009

Styan's Grasshopper Warblers (Locustella pleskei) are vulnerable species distributed in East-Asia only. Its known breeding sites in Korea are remote islets including Hongdo Islet, Chilbal Islet, Mara Islet, and Chuja Islets, and, therefore, the breeding biology of this species is still poorly known. This study was conducted on Mara Islet (N $33^{\circ}$ 06', E $126^{\circ}$ 16') from May to September 2008 to investigate the breeding status and breeding site characteristics of the grasshopper warblers. A total of 11 breeding pairs and their nests were found on trees and shrubs at artificially planted forests and hedges of Pinus thunbergii. The grasshopper warblers preferentially utilized the shrub trees for nesting places, and major nesting trees were Camellia japonica, Pittosporum tobira and Pinus thunbergii as nesting trees. Average heights of nesting trees and nests were $2.77{\pm}1.10m$ and $1.75{\pm}0.56m$, respectively. The grasshopper warblers selected lower shrubs and trees for nesting than randomly selected ones around them, probably to avoid strong and prevailed winds in flat and un vegetated environments on Mara Islet. The shape of nests was a round bowl-type, and measurements of nests were $11.9{\pm}0.5cm$ in exterior nest diameter, $11.1{\pm}1.1cm$ in height of exterior nest, $5.8{\pm}0.4cm$ in interior nest depth, and 6.0cm in interior nest diameter. It incubated eggs until the early August on Mara islet, and incubation periods of Mara Islet was possibly later than that of other areas. Furthermore, the clutch size in the study area was three, and they laid smaller number of eggs than normal clutch size (4~5 eggs) reported in other areas. Although we could not observe any nest predator on this species in the study area, selective cutting and pruning of trees will diminish dense shrub layer of forests. Therefore, it may affect the breeding of this threatened species which prefers dense shrubs of artificially planted forest of Pinus thunbergii. This study suggests that detailed and consistent further research on breeding biology and habitats of the grasshopper warblers are needed to conserve and manage of Pinus thunbergii forests on Mara Islet as an important breeding site of Styan's Grasshopper Warblers.

• Journal of The Korean Society of Grassland and Forage Science
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• v.25 no.3
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• pp.159-168
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• 2005

This experiment was carried out during the period from May to October 1998 to determine the effect of fermented sawdust swine manure application (SSM) on the herbage production of Japanese millet and soil properties in the Cheju brown volcanic ash soil. The randomized block design (T1 : basic chemical fertilizer, N 200 kg/ha + $P_2O_5\;300 kg/ha+K_2O$ 200kg/ha ; T2 : 1/2 basic chemical fertilizer, N $100+P_2O_5\;150+K_2O$ 100kg/ha; T3 : 1/2 basic SSM, N 100kg/ha, T4:basic SSM, N 200kg/ha; T5:2 times basic SSM, N 400 kg/ha ; T6:4 times basic SSM, N 800 kg/ha) was used. At the same application level of nitrogen 200kg/ha, the application of $100\%$ chemical fertilizer (T1) had significantly lower dry matter yield than that of $50\%$ chemical fertilizer and $50\%$ SSM (T2) or $100\%$ SSM (T4)(p<0.01). Dry matter yield increased with an increase of SSM application to N 400kg/ha level but decreased at N 800 kg/ha level. P, K and Ca contents of Japanese millet tended towards to decrease with an increase of SSM level. The application of chemical fertilizer lowered P and K content of Japanese millet in comparison with that of SSM (p<0.05). pH, available phosphorus. exchangeable potassium, Ca and Mg content of soil studied showed a significant increase with an increase of SSM application level (p<0.05). However, at the same application level of N 200kg/ha, there was statistically no significant difference between chemical fertilizer and SSM in those contents of soil after experiment. The bacterial number of soil among microbial population increased with an increase of SSM level, in June, 1998 (p<0.05), but there was no regular tendency, in October. The rate of bacteria to fungus in soil had a tendency to decrease with an increase of SSM level. In conclusion, it is recommended to use N 400kg/ha of SSM or N 100 kg/ha of chemical fertilizer+N 100 kg/ha of SSM for Japanese millet.

• Journal of the Speleological Society of Korea
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• no.95
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• pp.35-49
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• 2009

Ever since the beginning of time, caves not only have offered a place to live for humans but they have also been used as cultural spaces. That is, in the event of making some sounds in a location within the cave, the sound that is created is greatly magnified and sounds out as if it is being amplified from a giant megaphone. This, as we well know it, is known as the resonance effect. Here, the cave itself appears to function as a massive wind instrument. Especially in cases like the Altamira Cave (Spain) where cave paintings were found, the point where the cave drawings were found has commonalities in that it is a wide space and that it is usually discovered together with flutes and drums that are made with mammoth bones. We need to focus on this point. We can infer from these facts that the prehistoric people have carried out cultural activities along with their incantation rituals within those caves. In the meantime, amongst the Korean traditional arts, in the case of pansori which is a representative vocal genre, there have been examples where caves were used as practicing locations for those people who are training to perfect their singing. This is known as toguldoggong(土窟獨功) which literally means 'obtaining one's own art by oneself in the earth cave by practicing incessantly'. This process along with pokpodoggong (瀑布獨功) (same as above except that the location is by the waterfall) is the final training stage in order to become a recognized virtuoso on the part of the apprentice. This could be compared to the final annealing and finishing process of producing a metalwork. This has been a long tradition followed by most Korean traditional artists in order to perfect their sound which is harmonious with nature within natural surroundings. By honing in on this point, I have come to think about this matter repeatedly while coaching the university students in vocal singing. In short, I came to the conclusion that "the making of natural sounds will be obtained naturally within natural surroundings like caves!" Consequently, The Society for Studying Cave Sounds was inaugurated on January 1992 along with some of my students. We made use of times like vacations to go around exploring caves all over Jeju and carried out investigations of sounds along with cave exploration on an experimental basis. After 5 years, in September of 1997, we were able to host the first ever cave concert domestically at the Whale Nostril Cave(東岸鯨窟) on Wu-do. After that, we have been hosting the cave concert once every year. We have achieved a record of a total of 14 cave concerts until 2009 of this year. Out of these, 2 were held in Seokhwaeam Cave in Kangwon Province, another two were held in Manjang Cave which is a lava cave, and the remaining 10 were held in the Whale Nostril Cave of Wu-do. Along with that, I have carried out a special recording for the production of a cave music CD in May of 1999. This paper was written and organized by using the main materials that were derived from the experiences of using caves as concert halls in the past. It is hoped that this cave concert will offer a very unique experience to tourists who come to Jeju every year and give them the best possible superior natural sound effect that only Jeju caves can offer.

• Journal of Rhinology
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• v.25 no.2
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• pp.91-98
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• 2018

Background and Objectives: The present study evaluated the results of skin prick test using 55 allergens at 20 centers in the Republic of Korea in 2006, 2010, and 2014-2015. The aim was to assess changes in the positive rate of allergens according to temporal, regional, and environmental factors. Materials and Method: In total, 20 hospitals were selected based on the population distribution in the Republic of Korea. A skin prick test panel comprising 55 aeroallergens was distributed to 18 hospitals for this prospective study. The 2006 and 2010 skin prick test results were collected and analyzed retrospectively from 20 hospitals, while the 2014/2015 skin prick test results (from June 2014 to May 2015) were collected prospectively from 18 hospitals. Results: A total of 14,897 SPT test results were analyzed: 4,319 in 2006, 7,431 in 2010, and 1,852 in 2014/2015. The overall rate of skin prick test positivity to more than two allergens was significantly higher in males than females. The positive rates of alder pollens and birch, oak and ragweed pollen positivity were increased in older patients. Several positive rates were increased according to the temperature in spring. The positive rates for beech pollen, birch pollen, hazel pollen, oak pollen, Tyrophagus putrescentiae, mugwort, cat, Acarus siro, Lepidoglyphus destructor and Tyrophagus putrescentiae were significantly increased, while those of Cult rye pollen and dandelion were significantly decreased over the three test periods. The overall positive rate for allergens in Jeju province varied significantly from Seoul and other cities. Conclusion: Change in the positive rate of multiple aeroallergens was evaluated in the Republic of Korea over time. Our findings can be used to recommend aeroallergens suitable for inclusion in skin prick test panels in the Republic of Korea and will facilitate further investigation of changes in the patterns of allergic diseases.

• The Journal of Engineering Geology
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• v.31 no.1
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• pp.103-118
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• 2021

For management and preservation measures of lava tube, it is studied how the blasting vibration by constructions near Geomunoreum lava tubes in Jeju affect lava tube. 11 boreholes were drilled in study area, and in-situ blasting tests were conducted by changing from 0.5 kg to 10 kg charge per delay in those boreholes. The vibration velocity, which meets the regulatory vibration criterion during daytime, was estimated as below 0.276 cm/sec by analyzing the relationship between vibration velocity and vibration level. In addition, SRE and CRE were calculated from the results of in-situ blasting tests, and k-values were shown as 130.04 in SRE, 199.71 in CRE, respectively. Also, n-values were shown as -1.717 in SRE, -1.711 in CRE, respectively. Charge per delay were assessed based on these equations, and charges per delay had ranges of 0.57~7.42 kg/delay in estimation equation of vibration velocity, 0.21~5.29 kg/delay in SRE, and 0.04~5.51 kg/delay in CRE, considering the 0.2 kine vibration criterion for cultural heritage and the 20~100 m distance from vibration source. Additionally, the relationships which meet the criteria of 0.2 kine, were calculated by combining CRE in this study with the result of previous study. Allowable charges per delay, which meet the criteria of 0.2 kine, were evaluated as 1.07 kg/delay in 50 m, 5.13 kg/delay in 100 m and 22.26 kg/delay in 200 m distances. These relationships for each vibration velocity are useful to deduce charge per delay for the ground near Geomunoreum lava tube.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.335-344
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• 2023

Brachydiplax chalybea flavovittata, a climate-sensitive biological indicator species, was first observed and recorded at Jeju Island in Korea in 2010. Overwintering was recently confirmed in the Yeongsan River area. This study was aimed to predict the potential distribution patterns for the larvae of B. chalybea flavovittata and to understand its ecological characteristics as well as changes of population under global climate change circumstances. Data was collected both from the Global Biodiversity Information Facility (GBIF) and by field surveys from May 2019 to May 2023. We used for the distribution model among downloaded 19 variables from the WorldClim database. MaxEnt model was adopted for the prediction of potential and future distribution for B. chalybea flavovittata. Larval distribution ranged within a region delimited by northern latitude from Jeju-si, Jeju Special Self-Governing Province (33.318096°) to Yeoju-si, Gyeonggi-do (37.366734°) and eastern longitude from Jindo-gun, Jeollanam-do (126.054925°) to Yangsan-si, Gyeongsangnam-do (129.016472°). M type (permanent rivers, streams and creeks) wetlands were the most common habitat based on the Ramsar's wetland classification system, followed by Tp type (permanent freshwater marshes and pools) (45.8%) and F type (estuarine waters) (4.2%). MaxEnt model presented that potential distribution with high inhabiting probability included Ulsan and Daegu Metropolitan City in addition to the currently discovered habitats. Applying to the future scenarios by Intergovernmental Panel on Climate Change (IPCC), it was predicted that the possible distribution area would expand in the 2050s and 2090s, covering the southern and western coastal regions, the southern Daegu metropolitan area and the eastern coastal regions in the near future. This study suggests that B. chalybea flavovittata can be used as an effective indicator species for climate changes with a monitoring of their distribution ranges. Our findings will also help to provide basic information on the conservation and management of co-existing native species.

• Korean Journal of Environmental Biology
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• v.35 no.1
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• pp.13-20
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• 2017

Greenhouse gas emission from agricultural land is recognized as an important factor influencing climatic change. In this study, the national $CO_2$ emission was estimated for paddy soils, using soil GHG emission model (DNDC) with $1km^2$ scale. To evaluate the applicability of the model in Korea, verification was carried out based on field measurement data using a closed chamber. The total national $CO_2$ emission in 2015 was estimated at $5,314kt\;CO_2-eq$, with the emission per unit area ranging from $2.2{\sim}10.0t\;CO_2-eq\;ha^{-1}$. Geographically, the emission of Jeju province was particularly high, and the emission from the southern region was generally high. The result of the model verification analysis with the field data collected in this study (n=16) indicates that the relation between the field measurement and the model prediction was statistically similar (RMSE=22.2, ME=0.28, and $r^2=0.53$). More field measurements under various climate conditions, and subsequent model verification with extended data sets, are further required.