• Journal of Korean Society of Forest Science
• /
• v.103 no.1
• /
• pp.23-29
• /
• 2014

Open- to closed canopy stage and it's ecological characteristics in vegetation succession are commonly described, but poorly understood in Korea. Vegetation development on structure, environment and understory abundance were studied for 16 yr in post-clearcut Pinus densiflora forests in the southern Gangwon-do province by applying space-for-time approach. We sampled 210 plots (10 for structure and 200 for understory) for four seral stages (1yr, 3yr, 10yr and 16yr). After clear-cut, mean stem density increased gradually to $5,714{\pm}645$ stems/ha after 16 years and mean basal area was also from $5.5{\pm}0.7m^2/ha$ after 10 years and doubled at $10.0{\pm}1.6m^2/ha$ in 16 years. Woody debris and bared soil on the forest floor peaked at 11--- after 10 years and at 10.3--- after 3 years, respectively. In understory mean cover declined with all growth form groups following succession, but in richness, forb specie increased with structural development during 16 years. Our study suggested that overstory development did not suppressed whole understory properties especially in richness, thus appeared to act as a filter selectively constraining the understory characteristics. However only long-term studies are essential for elucidating patterns and processes that cannot be inferred form short-term or space-for-time researches. Strong negative relationship between overstory and understory characteristics in conventional models surely reexamined.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.20 no.6
• /
• pp.589-601
• /
• 2008

The variation of groundwater level near the Shingok weir has been analyzed. To consider the soil inhomogeneity, coefficient of effective permeability was computed to be 0.313 m/day in the horizontal direction, and 0.0423 m/day in vertical direction. Anisotropic ratio is 7.19. The river water level drawdown (caused by the removing of the weir) causes the groundwater level drawdown, and 3 months are required for the new steady condition. and groundwater flows from Han river toward Gulpo stream before the removing of the weir, but when the weir removed, the flow direction changes. The groundwater level falls maximum 30 cm in the areas under the influence of Han river, but, in the areas near Kulpo stream, groundwater level falls about 10 cm. The amount of groundwater use in the study area was investigated to be $52m^3/day$ and in this condition, groundwater level falls maximum 1m (before or after the removing of Shingok weir). therefore, the variation of groundwater level caused by the removing of Shingok weir is less than that caused by the usual use of groundwater.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.24 no.4
• /
• pp.467-474
• /
• 2018

The purpose of this study is related to automatic hull-form design for ships operating at two speeds. Research was conducted using a series 60 ($C_B=0.6$) ship as a target, which has the most basic ship hull-form. Hull-form development was pursued from the viewpoint of improving resistance performance. In particular, automatic hull-form design for a ship was performed to improve wave resistance, which is closely related to hull-forms. For this purpose, we developed automatic hull-form design software for ships by combining an optimization technique, resistance prediction technique and hull-form modification technique, appling the software developed to a target ship. A sequential quadratic programming method was used for optimization, and a potential-based panel method was used to predict resistance performance. A Gaussian-type modification function was developed and applied to change the ship hull-form. The software developed was used to design a target ship operating at two different speeds, and the performance of the resulting optimized hull was compared with the results of the original hull. In order to verify the validity of the program developed, experimental results obtained in model tests were compared with calculated values by numerical analysis.

• Smart Media Journal
• /
• v.10 no.4
• /
• pp.91-101
• /
• 2021

Visual communication based on socio-cultural context, such as emoticons on social media, is increasing. Therefore, it is necessary to study the visual expression of metonymy as a means to correctly understand the communication method in the age of visual culture. The purpose of this study is to explore how metonymy is visualized within a cultural context. Specifically, , a typical underlying phenomenon of metonymy expression, and the expression principles of various reproduced through it are identified by pairing them with the cultural context. Based on context theory, which is a representative discourse in the social science field, emoticons from in high context and emoticons in in low context were selected and compared as case study subjects. The major findings are: First, a visual application model of metonymy was proposed regarding the process through which metonymy is reproduced as a visual result. Second, the types of metonymy and their salience attribute applied to the emoticon expression method was identified in detail. Third, based on the contextual theory, how the characteristics of high-context visual metonymy differ from that of low-context visual metonymy were presented. In the future, the results of this study can be used as a criterion for judging the local acceptability and local suitability of design results in the design development process that requires the use of localization strategies.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.42 no.2
• /
• pp.171-179
• /
• 2022

In this study, the characteristics of algae mitigation according to dam operation were quantitatively analyzed for Uiam Lake, where the Chuncheon Dam is located upstream of the main stream, Uiam Dam is located downstream, and Soyang Dam is located in the tributary stream. Nine dam operation scenarios were applied to the event of the summer of 2018 (at that time an algae alert occurred) using the EFDC model, which is capable of calculating three-dimensional hydrodynamics and water quality levels such as those associated with chlorophyll-a. The dam operation scenarios were set to generate a flushing effect via discharges in the form of pulse waves from the upstream dams and by lowering the water level at the downstream dam. At Uiam Lake, the flushing effect was different depending on the operation of the dam, and the amount of algae reduction at each point was different owing to topographic characteristics and the different base water temperatures from BukHan River and Soyang River. With regard to a point located on the left bank, it was predicted that the peak level of chlorophyll-a would be reduced by approximately 50 % or more upon pulsed discharge at 50 m³/s for three days at Soyang Dam. However, for the right bank, the amount of discharge from Soyang Dam had little effect on algae mitigation. Therefore, an appropriate dam operation could be effective for algae mitigation at specific points in the water body where large dams exist upstream and downstream, such as at Uiam Lake, in an emergency situation in which algal blooms rapidly.

• Journal of Korea Water Resources Association
• /
• v.46 no.12
• /
• pp.1193-1207
• /
• 2013

Increase of impervious area caused by overdevelopment has led to increase of runoff and then the problem of flooding and NPS were brought up. In addition, as decrease of base flow made groundwater level to decline, a stream that dries up is issued. low impact development (LID) method which is possible to mimic hydrological water cycle, minimize the effect of development, and improve water cycle structure is proposed as an alternative. As introduction of LID in domestic increases, the study on small watershed is in process mainly. Also, analysis of property of hydrological runoff and load on midsize watershed, like sewage treatment district, is required, the study on it is still insufficient. So, area applying LID practices from watershed of Dongrae stream is pinpointed and made the ratio and then expand it to watershed of Oncheon stream. Among low impact development practices, Green Roof, Porous Pavement, and Bio- retention are selected for the application considering domestic situations and simulated with SWMM-LID model of each watershed and improvement of water cycle and reduction of non-point pollution loads was analysed. Improvement of water cycle and reduction of non-point pollution loads were analyzed including the property of rainfall and soil over long term simulation. The model was executed according to scenario based on combination of LID as changing conductivity in accordance with soil type of the watershed. Also, this study evaluated area of LID application that meets the efficiency of conventional management as a criteria for area of LID practices applying to sewer treatment district by comparing the efficiency of LID application with that of conventional method.

• Geophysics and Geophysical Exploration
• /
• v.5 no.4
• /
• pp.280-290
• /
• 2002

Three-dimensional (3-D) electromagnetic (EM) modeling algorithm has been developed using finite element method (FEM) to acquire more efficient interpretation techniques of EM data. When FEM based on nodal elements is applied to EM problem, spurious solutions, so called 'vector parasite', are occurred due to the discontinuity of normal electric fields and may lead the completely erroneous results. Among the methods curing the spurious problem, this study adopts vector element of which basis function has the amplitude and direction. To reduce computational cost and required core memory, complex bi-conjugate gradient (CBCG) method is applied to solving complex symmetric matrix of FEM and point Jacobi method is used to accelerate convergence rate. To verify the developed 3-D EM modeling algorithm, its electric and magnetic field for a layered-earth model are compared with those of layered-earth solution. As we expected, the vector based FEM developed in this study does not cause ny vector parasite problem, while conventional nodal based FEM causes lots of errors due to the discontinuity of field variables. For testing the applicability to high frequencies 100 MHz is used as an operating frequency for the layer structure. Modeled fields calculated from developed code are also well matched with the layered-earth ones for a model with dielectric anomaly as well as conductive anomaly. In a vertical electric dipole source case, however, the discontinuity of field variables causes the conventional nodal based FEM to include a lot of errors due to the vector parasite. Even for the case, the vector based FEM gave almost the same results as the layered-earth solution. The magnetic fields induced by a dielectric anomaly at high frequencies show unique behaviors different from those by a conductive anomaly. Since our 3-D EM modeling code can reflect the effect from a dielectric anomaly as well as a conductive anomaly, it may be a groundwork not only to apply high frequency EM method to the field survey but also to analyze the fold data obtained by high frequency EM method.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.21 no.4
• /
• pp.50-63
• /
• 2018

The rapid urbanization had led to a distortion of natural hydrological cycle system. The change in hydrological cycle structure is causing streamflow depletion, changing the existing use tendency of water resources. To manage such phenomena, a streamflow depletion impact assessment technology to forecast depletion is required. For performing such technology, it is indispensable to build GIS-based spatial data as fundamental data, but there is a shortage of related research. Therefore, this study was conducted to use the use of GIS-based time series spatial data for streamflow depletion assessment. For this study, GIS data over decades of changes on a national scale were constructed, targeting 6 streamflow depletion impact factors (weather, soil depth, forest density, road network, groundwater usage and landuse) and the data were used as the basic data for the operation of continuous hydrologic model. Focusing on these impact factors, the causes for streamflow depletion were analyzed depending on time series. Then, using distributed continuous hydrologic model based DrySAT, annual runoff of each streamflow depletion impact factor was measured and depletion assessment was conducted. As a result, the default value of annual runoff was measured at 977.9mm under the given weather condition without considering other factors. When considering the decrease in soil depth, the increase in forest density, road development, and groundwater usage, along with the change in land use and development, and annual runoff were measured at 1,003.5mm, 942.1mm, 961.9mm, 915.5mm, and 1003.7mm, respectively. The results showed that the major causes of the streaflow depletion were lowered soil depth to decrease the infiltration volume and surface runoff thereby decreasing streamflow; the increased forest density to decrease surface runoff; the increased road network to decrease the sub-surface flow; the increased groundwater use from undiscriminated development to decrease the baseflow; increased impervious areas to increase surface runoff. Also, each standard watershed depending on the grade of depletion was indicated, based on the definition of streamflow depletion and the range of grade. Considering the weather, the decrease in soil depth, the increase in forest density, road development, and groundwater usage, and the change in land use and development, the grade of depletion were 2.1, 2.2, 2.5, 2.3, 2.8, 2.2, respectively. Among the five streamflow depletion impact factors except rainfall condition, the change in groundwater usage showed the biggest influence on depletion, followed by the change in forest density, road construction, land use, and soil depth. In conclusion, it is anticipated that a national streamflow depletion assessment system to be develop in the future would provide customized depletion management and prevention plans based on the system assessment results regarding future data changes of the six streamflow depletion impact factors and the prospect of depletion progress.

• The korean journal of orthodontics
• /
• v.28 no.5 s.70
• /
• pp.855-864
• /
• 1998

The purposes of this study were to evaluate the cephalometric characteristics of Korean female patients with Class II division 2 malocclusion and to compare Korean females with Caucasian females who had same type of malocclusion. All of the samples had Class II division 2 malocclusion with deep overbite (more than 4mm) and full permanent dentition. These samples were divided into two groups according to the races: Group 1(N=16; Korean females; average age=18Y 2M) and Group 2 (N:20; Caucasian females; average age=14Y 2M). The pretreatment lateral cephalograms were measured, analyzed and compared by using 38 variables and independent t-test. And the results were as follows: 1. Although there were no differences in Overbite, SN to mandibular plane angle, Palatomandibular plane angle, and FMA between Group 1 and 2, the other vertical relation variables of maxilla and mandible (SN to palatal plane angle, SN to occlusal plane angle, ODI) of Group 1 showed more clockwise rotation tendency of occlusal plane and less hypodivergency tendency than those of Group 2. 2. There were no differences in mandibular body length and ramus height between Group 1 and 2 except small upper genial angle of Group 1. There was less counterclockwise rotation tendency of mandible in Group 1. 3. There were no statistical significant differences in UAFH/LAFH and PFH/AFH between Group 1 and 2. 4. Although there were no differences of overjet and anteroposterior position of mandible between Group 1 and 2, the position of maxilla of Group 1 was more retropositioned than that of Group 2. 5. Except the more protrusion of lower incisor to A-Pog of Group 1, there were no differences of inclination and distance of upper and lower incisors to basal plane between Group 1 and 2. 6. The distance from upper- first molar to palatal plane showed no difference between Group 1 and 2. But the distance from lower first molar to mandibular plane of Group 1 was greater than that of Group 2. So it may be partially related to the clockwise rotation of occlusal plane and the less counterclockwise rotation tendency of mandible of Group 1. 7. Group 1 had more protrusive upper and lower lips than Group 2.

• Journal of Korea Water Resources Association
• /
• v.51 no.10
• /
• pp.863-874
• /
• 2018

The purpose of this study is to evaluate the future climate change impact on stream aquatic ecology health of Han River watershed ($34,148km^2$) using SWAT (Soil and Water Assessment Tool) and random forest. The 8 years (2008~2015) spring (April to June) Aquatic ecology Health Indices (AHI) such as Trophic Diatom Index (TDI), Benthic Macroinvertebrate Index (BMI) and Fish Assessment Index (FAI) scored (0~100) and graded (A~E) by NIER (National Institute of Environmental Research) were used. The 8 years NIER indices with the water quality (T-N, $NH_4$, $NO_3$, T-P, $PO_4$) showed that the deviation of AHI score is large when the concentration of water quality is low, and AHI score had negative correlation when the concentration is high. By using random forest, one of the Machine Learning techniques for classification analysis, the classification results for the 3 indices grade showed that all of precision, recall, and f1-score were above 0.81. The future SWAT hydrology and water quality results under HadGEM3-RA RCP 4.5 and 8.5 scenarios of Korea Meteorological Administration (KMA) showed that the future nitrogen-related water quality in watershed average increased up to 43.2% by the baseflow increase effect and the phosphorus-related water quality decreased up to 18.9% by the surface runoff decrease effect. The future FAI and BMI showed a little better Index grade while the future TDI showed a little worse index grade. We can infer that the future TDI is more sensitive to nitrogen-related water quality and the future FAI and BMI are responded to phosphorus-related water quality.