• Korean Journal of Environment and Ecology
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• v.34 no.6
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• pp.558-572
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• 2020

The purpose of this study was to classify the types of degraded areas of Mt. Jirisan section in Baekdudaegan and survey the actual condition of each damage type to use it as basic data for the direction of the restoration of damaged areas according to damage type based on the vegetation information of reference ecosystem. The analysis of the Mt. Jirisan section's actual degraded conditions showed that the total number of patches of degraded areas was 57, and the number of patches and size of degraded areas was higher at the low average altitude and gentle slope. Grasslands (deserted lands) and cultivated areas accounted for a high portion of the damage types, indicating that agricultural land use was a major damage factor. The survey on the conditions of 14 degraded areas showed that the types of damage were classified into the grassland, cultivated area, restoration area, logged-off land, and bare ground. The analysis of the degree of disturbance (the ratio of annual and biennial herb, urbanized index, and disturbance index) by each type showed that the simple single-layer vegetation structure mostly composed of the herbaceous and the degree of disturbance were high in the grassland and cultivated land. The double-layer vegetation structure appeared in the restoration area where the pine seedlings were planted, and the inflow of naturalized plants was especially high compared to other degraded areas due to disturbances caused by the restoration project and the nearby hiking trails. Although the inflow of naturalized plants was low because of high altitude in bare ground, the proportion of annual and biennial herb was high, indicating that all surveyed degraded areas were in early succession stages. The stand ordination by type of damage showed the restoration area on the I-axis, cultivated area, grassland, logged-off land, and bare ground in that order, indicating the arrangement by the damage type. Moreover, the stand ordination of the degraded areas and reference ecosystem based on floristic variation showed a clear difference in species composition. This study diagnosed the status of each damage type based on the reference ecosystem information according to the ecological restoration procedure and confirmed the difference in species composition between the diagnosis result and the reference ecosystem. These findings can be useful basic data for establishing the restoration goal and direction in the future.

• Korean Journal of Plant Resources
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• v.35 no.5
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• pp.594-606
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• 2022

This study was conducted to figure out the environment factors including vegetation structure and soil characteristics in natural habitats of Sageretia thea, and offers the basic information for habitats conservation and proliferation. The natural habitats of Sageretia thea were located at altitudes between 0~370 m with inclinations ranged as 3~35°. Through the vegetation research, the dominant species of tree layers were found to be divided into four communities. Cornus macrophylla (Com. I), Pinus thunbergii - Cinnamomum camphora (Com. II), Machilus thunbergii (Com. III), and Pinus thunbergii (Com. IV). The Species diversity (H') was 1.397~1.455, evenness (J') was 0.972~0.986, and dominance (D) was found to be 0.014~0.028. As a result of the physicochemical characteristics of soils, habitats soil mainly consisted of sandy soil and sandy loam soil. The average soil pH was 5.28~5.98, electronic conductivity was 0.22~63 ds/m, soil organic matter was 13.33~19.33 cmol⁺/kg, Exchange cations were appeared in the order of Ca²⁺, Mg²⁺, K⁺, and Na⁺. The Ordination result showed that Correlation coefficient between communities and environmental factors were significantly correlated with 4 main factors altitude, electronic conductivity, cation exchange capacity, exchangeable Na⁺. As expected, The result of this study will be helpful information on the preservation and mass production for use.

• Journal of Korean Society of Forest Science
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• v.111 no.2
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• pp.201-223
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• 2022

Currently, species extinctions are increasing due to climate change and continued anthropogenic impact. We selected 300 species for conservation with emphasis on plants co-occurring in the Baekdudaegan area, which is a large ecological axis of Korea. We aimed to investigate the vegetation community and environmental characteristics of Zabelia tyaihyonii in the limestone habitat among the target plant species in the Baekdudaegan region to derive effective conservation strategies. In Danyang-gun, Yeongwol-gun, and Jecheon-si, we selected 36 investigation sites where Z. tyaihyonii was present. We investigated the vegetation, flora, soil and physical environment. We also found notable plants such as Thalictrum petaloideum, Sillaphyton podagraria, and Neillia uekii at the investigation sites. We classified forest vegetation community types into 4 vegetation units and 7 species group types. With canonical correspondence analysis (CCA) of the vegetation community and habitat factors, we determined the overall explanatory power to be 75.2%, and we classified the environmental characteristics of the habitat of Z. tyaihyonii into a grouping of three. Among these, we detected a relationship between the environmental factors elevation, slope, organic matter, rock ratio, pH, potassium, and sodium. We identified numerous rare and endemic plants, including Thalictrum petaloideum, in the investigation site, and determined that these groups needed to be preserved at the habitat level. In the classification of the vegetation units analyzed based on the emerging plants and the CCA, we reaffirmed the uniqueness and specificity of the vegetation community in the habitat of Z. tyaihyonii. We anticipate that our results will be used as scientific evidence for the empirical conservation of the native habitats of Z. tyaihyonii.

• The korean journal of orthodontics
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• v.25 no.5 s.52
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• pp.525-541
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• 1995

This study was designed to investigate force systems and tooth movements produced by retraction archwire during retraction of four maxillary incisors after the maxillary canine retraction into the maxillary first premolar extraction space using the computer-aided three-dimensional finite element method. A three-dimensional finite element model, consisting of 2248 elements and 3194 nodes, was constructed. The model consisted of maxillary teeth and surrounding periodontal membranes, .022'$\times$.028'-slot brackets, and 5 types of retraction archwires(.019'$\times$.025' stainless steel archwire) modeled using the beam elements. The contact between the wire and the bracket slot was modeled using the gap elements because of the non-linear elastic behaviors of the contact between them. The forces and moments, End displacements produced by retraction archwire were measured at various conditions to investigate the difference according to types of loops, magnitudes of activation force, gable angle, and anterior lingual root torque. The results were expressed quantitative and visual ways in the three-dimensional method. The following conclusions can be drawn from this study.1. When the tear-drop loop archwire was activated, the mesio-distal and lingual translational movements of the teeth helped to close the extraction space, but unwanted movements of the teeth including intrusions and extrusions, and rotational movements in each direction occurred. 2. Activation of T-loop archwire compared with those of other types of retraction archwires produced the least translational movements of the teeth helped to space closure and also the least unwanted movements of the teeth. 3. Increasing amount of activation in the tear-drop archwire led not only to increase of translational movements of the teeth helped to space closure, but also to increase of unwanted movements of the teeth. 4. Addition of gable bend in the tear-drop archwire helped anterior teeth to translational movements in the mesio-distal direction, but increased unwanted movements of the teeth 5. Addition of anterior lingual root torque in the tear-drop archwire helped central and lateral incisor to improve their facio-lingual inclination, but increased unwanted movements of the teeth.

• Journal of Biosystems Engineering
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• v.11 no.2
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• pp.31-40
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• 1986

Cylindrical and conical types of grain-straw separation equipment which has a stationary crimped sieve drum with rotating inner rotor were constructed. The developed equipments were tested to investigate the characteristics of separating performance under various mechanical conditions and crop conditions. As increase of the inclination of equipment and decrease of pitch of cover vane, the grain recovery was increased while straw rejection was decreased. The grain recovery and overall efficiency were decreased as the rotor speed and feeding velocity were increased for both varieties of rice, moisture contents, and test equipments. Conical prototype equipment performed higher straw rejection, lower grain recovery, and lower power requirement. However, separation performance of conical type equipment was more widely varied with various test conditions compared to cylindrical one. The performance of both equipments showed relatively insensitive to crop feedrate and crop properties, such as variety, moisture content, and grain-to-straw ratio.

• Journal of The Korean Society of Grassland and Forage Science
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• v.37 no.2
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• pp.132-139
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• 2017

This study was conducted to find out the effects of over seeding using new grass varieties orchardgrass 'Kordione' and 'Onnuri', and tall fescue 'Greenmaster' on botanical composition and dry matter productivity from 2013 to 2016 in low productivity hilly pasture, middle area of Korea. There were used 3 grass seed mixture types made of different compositions and amounts {T1: control - no over seeding, T2: tall fescue (TF) 'Greenmaster' $18kg\;ha^{-1}$, orchardgrass (OG) 'Kordione' $9kg\;ha^{-1}$, Perennial ryegrass (PRG) 'Linn' $5kg\;ha^{-1}$, and Kentucky bluegrass (KBG) 'Kenblue' $2kg\;ha^{-1}$, T3: TF 'Greenmaster' $9kg\;ha^{-1}$, OG 'Kordione' $18kg\;ha^{-1}$, PRG 'Linn' $5kg\;ha^{-1}$, and KBG ' Kenblue' $2kg\;ha^{-1}$, T4: TF 'Greenmaster' $9kg\;ha^{-1}$, OG 'Onnuri' $18kg\;ha^{-1}$, PRG 'Linn' $5kg\;ha^{-1}$, and KBG 'Kenblue' $2kg\;ha^{-1}$}. In the botanical composition of grassland, T1 nearly remained constant in other seasons while ratio of weeds were increased in summer season. T2 was better than control (T1) in portion of grass ratio, which has increased by 80%. In the early time of establishment, the portions of OG were increased in T2, but TF rate was increased after 3 years later when grass was established. T3 and T4 showed a very similar patterns, grass ratio had increased by 80% and the portion of KBG had increased as time passed. T2 ($129,763kg\;ha^{-1}$) was showed the highest dry matter yield than other treatments (T1: $6,756kg\;ha^{-1}$, T3: 9641, and T4: 10,738) in 2016.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.1
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• pp.101-111
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• 2015

Stream restoration projects have become threats to riparian ecosystem in Rep. of korea. Riparian wildlife becomes isolated and the animals are often experience difficulties in crossing riparian corridors. The purposes of this study is to select suitable wildlife passages for wild animals crossing riparian corridors. Maximum entropy model and snow tracking data on embankment in winter seasons were used to develop species distribution models to select suitable wildlife passages for water deer. The analysis suggests the following. Firstly, most significant factors for water deer's habitat in area nearby riparian area are shown to distance to water, age-class, land cover, slope, aspect, digital elevation model, tree density, and distance to road. For the riparian area, significant factors are shown to be land cover, size of riparian area, distance to tributary, and distance to built-up. Secondly, the suitable wildlife passages are recommended to reflect areas of high suitability with Maximum Entropy model in riparian areas and the surrounding areas and moving passages. The selected suitable areas are shown to be areas with low connectivity due to roads and vertical levee although typical habitats for water deer are forest, grassland, and farmland. In addition, the analysis of traces on snow suggests that the water deer make a detour around the artificial structures. In addition, the water deer are shown to make a detour around the fences of roads and embankment around farmland. Lastly, the water deer prefer habitats around riparian areas following tributaries. The method used in this study is expected to provide cost-efficient and functional analysis in selecting suitable areas.

• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.271-283
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• 2006

A systematic water quality survey was conducted in August, 2005 for a drinking water supply reservoir (the Jeolgol reseuoir located in an island), which is at an early stage of impoundment, to investigate the causes of water color deterioration of the reservoir and the clogging of filter beds of a water treatment plant. The reservoir shape was simple and its average depth was 5.5 m, increasing from upreservoir toward the downreservoir end near the dam. Dissolved oxygen (DO) and chloropllyll-a (chi-a) showed a large variation while water temperature had a smaller range. Transparency ranged from 0.6 to 0.9 m (average 0.7 m). The average value of turbidity was 9.3 NTU, ranging from 8.0 ${\sim}$ 12.1 NTU. The transparency and the turbidity appear to be affected by a combination of biological and non-biological factors. The poor transparency was explained by an increase of inorganic colloids and algal bloom in the reservoir. The blockage of the filter bed was attributed to the oversupply of phytoplanktons from the reservoir. The range and the average concentration of chi-a within the reservoir were 31.6 ${\sim}$ 258.9 ${\mu}g\;L^{-1}$, 123.6 ${\mu}g\;L^{-1}$ for the upper layer, and 17.0 ${\sim}$ 37.4 ${\mu}g\;L^{-1}$, 26.5 ${\mu}g\;L^{-1}$ for the bottom layer, respectively. A predominant species contributing the algal bloom was Dinophyceae, Peridinium bipes f. occultatum. The distribution of Peridinium spp. was correlated with chi-a concentrations. The standing crop of phytoplankton was highest in the upreservoir with $8.5\;{\times}\;103\;cells\;mL^{-1}$ and it decreased toward the downresevoir. Synedra of Bacillariophyceae and Microcystis aeruginosa of Cyanophyceae appeared to contribute to the algal bloom, although they are not dominated. It is mostly likely that sloped farmlands located in the watershed of the reservoir caused water quality problems because they may contain a significant amount of the nutrients originated from fertilizers. In addition, the aerators installed in the reservoir and a shortage of the inflowing water may be related to the poor water quality. A long-term monitoring and an integrated management plan for the water quality of the watersheds and the reservoir may be required to improve the water quality of the reservoir.

• Korean Journal of Environment and Ecology
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• v.29 no.3
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• pp.333-343
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• 2015

This research aims at identifying the goshawk's possible and replaceable breeding ground by using the MaxEnt prediction model which has so far been insufficiently used in Korea, and providing evidence to expand possible protection areas for the goshawk's breeding for the future. The field research identified 10 goshawk's nests, and 23 appearance points confirmed during the 3rd round of environmental research were used for analysis. 4 geomorphic, 3 environmental, 7 distance, and 9 weather factors were used as model variables. The final environmental variables were selected through non-parametric verification between appearance and non-appearance coordinates identified by random sampling. The final predictive model (MaxEnt) was structured using 10 factors related to breeding ground and 7 factors related to appearance area selected by statistics verification. According to the results of the study, the factor that affected breeding point structure model the most was temperature seasonality, followed by distance from mixforest, density-class on the forest map and relief energy. The factor that affected appearance point structure model the most was temperature seasonality, followed by distance from rivers and ponds, distance from agricultural land and gradient. The nature of the goshawk's breeding environment and habit to breed inside forests were reflected in this modeling that targets breeding points. The northern central area which is about $189.5 km^2$(2.55 %) is expected to be suitable breeding ground. Large cities such as Cheongju and Chungju are located in the southern part of Chungcheongbuk-do whereas the northern part of Chungcheongbuk-do has evenly distributed forests and farmlands, which helps goshawks have a scope of influence and food source to breed. Appearance point modeling predicted an area of $3,071 km^2$(41.38 %) showing a wider ranging habitat than that of the breeding point modeling due to some limitations such as limited moving observation and non-consideration of seasonal changes. When targeting the breeding points, a specific predictive area can be deduced but it is difficult to check the points of nests and it is impossible to reflect the goshawk's behavioral area. On the other hand, when targeting appearance points, a wider ranging area can be covered but it is less accurate compared to predictive breeding point since simple movements and constant use status are not reflected. However, with these results, the goshawk's habitat can be predicted with reasonable accuracy. In particular, it is necessary to apply precise predictive breeding area data based on habitat modeling results when enforcing an environmental evaluation or establishing a development plan.

• The Journal of the Petrological Society of Korea
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• v.26 no.3
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• pp.201-219
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• 2017

The Jinan Basin which includes Maisan locates in the central part of the northern boundary of the Yeongnam Massif. The basement rocks of the Jinan Basin and surrounding area are Precambrian gneiss and Mesozoic granite which were exposed on the surface before Cretaceous. The Jinan Basin, one of the Cretaceous pull-apart basins in South Korea, formed along the Yongdong-Gwangju fault system. Maisan is composed of conglomerate deposited in the eastern slope of the Jinan Basin showing the shape of horse ears and the unusual topography where many tafonies were developed. The strike slip fault that caused the Jinan Basin was connected to the deep depth so that the magma formed at 200 km depth could have extruded on the surface causing active volcanic activity in and around the Jinan basin. As a result, Cheonbansan composed of pyroclastic rocks, Gubongsan consisting of volcanic neck and WoonilamBanilam formed by the lava flow, appear around Maisan forming a specific terrain. After the formation of the Jinan Basin and surrounding volcanic rocks, they uplifted to form mountains including Masian; the uplifting time may be ca. 69-38 Ma. At this time, the Noryeong mountain range may be formed in the regions which extended from Chugaryeong through Muju and Jinan to Hampyeong dividing the Geumgang and Seomjingang water systems. Due to the ecological barrier, the Noryeong mountain range, Coreoleuciscus splendidus living in the Geumgang water systems was differentiated from that in the Soemjingang water system. In addition, the Geumgang and Mangyeong-Dongjingang water systems were separated by the Unjangsan, which developed in the NNW direction. As a result, diverse ecosystem have been established in and around Maisan and at the same time, diverse cultural and historical resources related to Maisan's unique petrological features, were also established. Therefore, Maisan and surrounding area can be regarded as a place where a geotourism can be successfully established by combining the ecological, cultural and historical resources with a geological heritage. Therefore Maisan and surrounding areas have a high possibility to be a National Geopark and UNESCO Global Geopark.