• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.3
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• pp.147-153
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• 2013

There exist various types of the WEC (Wave Energy Converter), and among them, the point absorber is the most popularly investigated type. However, it is difficult to find examples of systematically measured data analysis for the design of the point absorber type of power buoy in the world. The study investigates the wave load acting on the point absorber type resonance power buoy wave energy extraction system proposed by Kweon et al. (2010). This study analyzes the time series spectra with respect to the three-year wave data (2002.05.01~2005.03.29) measured using the pressure type wave gage at the seaside of north breakwater of Hupo harbor located in the east coast of the Korean peninsula. From the analysis results, it could be deduced that monthly wave period and wave height variations were apparent and that monthly wave powers were unevenly distributed annually. The average wave steepness of the usual wave was 0.01, lower than that of the wind wave range of 0.02-0.04. The mode of the average wave period has the value of 5.31 sec, while mode of the wave height of the applicable period has the value of 0.29 m. The occurrence probability of the peak period is a bi-modal type, with a mode value between 4.47 sec and 6.78 sec. The design wave period can be selected from the above four values of 0.01, 5.31, 4.47, 6.78. About 95% of measured wave heights are below 1 m. Through this study, it was found that a resonance power buoy system is necessary in coastal areas with low wave energy and that the optimal design for overcoming the uneven monthly distribution of wave power is a major task in the development of a WEF (Wave Energy Farm). Finding it impossible to express the average spectrum of the usual wave in terms of the standard spectrum equation, this study proposes a new spectrum equation with three parameters, with which basic data for the prediction of the power production using wave power buoy and the fatigue analysis of the system can be given.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.2
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• pp.583-595
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• 2014

Currently, Korean transportation policies are aiming for increase of safety and environment-friendly and efficient operation, by avoiding construction and expansion of roads, and upgrading road alignments and facilities. This is revealed by that there have been 22 road expansion projects (30%) and 50 road improvement projects (70%) under the 3rd Five-Year Plan for National Highways ('11~'15), while there were 53 road expansion projects (71%) and 22 road improvement projects (29%) under the 2nd Five-Year Plan for National Highways. For more effective road improvement projects, there is a need of choosing projects after an objective and scientific safety assessment of each road, and assessing safety improvement depending on projects. This study is intended to develop a model for this road safety analysis and assessment. The major objective of this study is creating a road safety analysis and assessment model appropriate for Korean society, based on the HSM (Highway Safety Manual) of the U.S. In order to build up data for model development, the sections thought to have identical geometrical structure factors in 5 lines, Cheonbuk province, were divided as homogeneous sections, and representative values of geometric structures, facilities, traffic volume, climate conditions and land usage were collected from the 1,452 sections divided. In order to build up data for model development, the sections thought to have identical geometrical structure factors in 5 lines, Cheonbuk province, were divided as homogeneous sections, and representative values of geometric structures, facilities, traffic volume, climate conditions and land usage were collected from the 1,452 sections divided. The collected data was processed correlation analysis of each road element was implemented to see which factor had a big effect on traffic accidents. On the basis of these results, then, an accident model was established as a negative binomial regression model.Using the developed model, an Crash Modification Factor (CMF) which determines accident frequency changes depending on safety performance function (SPF) predicting the number of accident occurrence through traffic volume and road section expansion, road geometric structure and traffic properties, was extracted.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.815-826
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• 1994

Skew bridges are found frequently in new bridge construction due to geographical conditions when new constructing bridges are put across the existing highways, railroads or rivers. This study is to investigate the static behaviors of the steel deck plates of skew bridges which are increasingly used in bridges due to outstanding quality of structural steels, development of welding techniques, in order to reduce dead loads and period of constructions. The static behaviours of steel deck plates are analyzed using general purpose FE code SAP90 by modeling the skewed deck plates with rigorous finite elements, as the skew angles vary. The results of finite element analysis for the behaviors of steel deck plates and concrete slabs in acute, obtuse corners and center of decks are compared and discussed as the skew angles vary from $90^{\circ}$ to $30^{\circ}$. Two types of decks are treated, as isotropic plates and orthotropic plates, respectively. From the results of finite element analysis, it is found that more moments, reactions, and deflections occur at the obtuse corners than at the center of skewed decks regardless of isotropy or orthotropy. Especially, in case of the skewed deck plates with skew angles less than 45 degrees, significantly large discrepancies for the values of those internal forces are shown between the skewed and right deck plates. This study estimates the characteristics of deck behaviors according to skew angles, and proposes limitations of skew angles and the ciritical regions of decks.

• Journal of the Korean Association of Geographic Information Studies
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• v.2 no.2
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• pp.27-44
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• 1999

Digital maps produced in Korea are various in scale and include a lot of geographic and attribute data. In this study, it is argued that, to reduce the production cost and the difficulties for renewal, it is necessary to establish the already nationally drawn 1:5,000 scale digital maps as the base maps and simplify them as much as the TIGER files in the U.S. The comprehensive data included in the digital maps in Korea are mostly land use information, which are supposed to be established separately from the digital maps. The land use information system could be maintained and updated cheaply and frequently at the local government level. In response to common needs, the land use information could be imported to GIS and used for analyses. As technologies and societies changes, the Census questions and methodologies should be changed for better uses. Along with GIS, the Census would be developed and processed more reliably and efficiently. Also, it is recommended for Korean government to develop the Census Tract and Block Group system. Current Eup, Myon, Dong as basic units for Census information may not be useful or effective for micro level urban analyses and public service planning activities because of their large population and land areas. It is recommended that optimum population of a Census Tract be 5,000 and a Block Groups 1,500, and one Census Tract includes 1~9 Block Groups. It is recommend that Census Tract and Block Group boundary lines be decided flexibly in light of population, physical features, socio-economic attributes, and tradition. For urban analyses using GIS, socio-economic census data, city government's information such as parcel data and building permit data, survey data, and satellite image data could also be used. The existence of Census Tracts and Block Groups as well as GIS could help for the data and methods to be useful for urban analyses and public service provisions.

• Korean Journal of Environment and Ecology
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• v.27 no.2
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• pp.219-229
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• 2013

This research is performed in order to suggest seasonal effective research time that is applied to wild birds research which lives in a forest. The subject area of this research is Mulgun-ri village forest in Samdong-Myeon, Namhe-gun. To investigate suitability of the project, existing land-use, existing vegetation, vegetational structure, and etc. of the subject and whole area are figured out. To suggest adequate research time, based on seasonal sun rise and set time for 3days, repetitive research is performed at hourly intervals. The subject area is connected with a forest and is possible for forest wild birds to flows in and provides various habitats and feeding areas. And also the subject area is a appropriate area for wild birds research and is like a natural forest in that a layer structure development of the forest itself, a distribution of Zelkova serrata and Aphananthe aspera and so on. 105 species which is observed in subject area are categorized and mountain birds are classified. After time-based peak value is selected in each season, hourly species richness, diversity, and index of similarity are analyzed as compared with the appearing number of species and individual bird. As a result, 7~11 hour is the most effective time in spring, and 8~9 hour is the best time. In summer, 6~9 hour is the most appropriate time when whole appearing species are similar to species structure. In fall, 7~11(30~60 minutes after sun rise) when wild birds movements are vigorous is analyzed easy to observe and 8~9 hour is the most appropriate research time because each analysis shows the best values. In winter, 7~12 hour is the most effective time although 10~11 hour is the best time but it is decided that similar results are drawn because hourly deviation is not so big except 1 hour before sun rise. In every four season, it is decided that 30~60 minutes after sun rise is appropriate to research a group of wild birds in the subject area.

• Korean Journal of Environment and Ecology
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• v.34 no.3
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• pp.259-270
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• 2020

Plants Social Network (PSN) was first used in recent studies to incorporate the plant sociology methods for the understanding of plant society with the social network analysis methods that have recently attracted attention in the social science and visualize and analyze a PSN. The process of construction and analysis on PSN proceeds in the order of setting up the survey area, investigating the appearance plants species on plots of 100㎡, analyzing the interspecific association, building the sociogram, and analyzing the network structure and centrality. This study established a PSN by investigating the appearance species after installing 708 plots to include various dominant vegetational physiognomies in Busan Metropolitan City, where coastal and inland vegetation could be observed simultaneously. The survey found a total of 195 species, including 42 species of evergreen, 151 species of deciduous trees, and 2 species of semi-evergreen trees. The interspecies binding analysis was performed with the focus on the total number of species. It showed the number of friendly species in the order of Eurya japonica (47 species), Trachelospermum asiaticum (46 species), Linder glauca (44 species), Sorbus alnifolia (44 species), and Ligustrum japonicum (41 species). Based on it, we generated a sociogram using Gephi 0.9.2 program. The sociogram was divided into groups that appeared mostly on the coast and those that did not, reflecting the geographical distribution characteristics of forest vegetation in Busan. The analysis of the network structured showed 1,709 links and an average of 17.5 species having interspecies binding with a species. The density was 0.09, the diameter was 5, and the average path distance was 2.268. We concluded that various PSNs should be established in the future for precise comparative analysis of network characteristics in the social science field. In the PSN of Busan Metropolitan City, Eurya japonica, Linder glauca, Ligustrum japonicum, and Trachelospermum asiaticum showed high centrality.

• Korean Journal of Remote Sensing
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• v.33 no.5_2
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• pp.699-708
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• 2017

The present study was to develop an approach for predicting soybean yield using a crop growth simulation model at the regional level where the detailed and site-specific information on cultivation management practices is not easily accessible for model input. CROPGRO-Soybean model included in Decision Support System for Agrotechnology Transfer (DSSAT) was employed for this study, and Illinois which is a major soybean production region of USA was selected as a study region. As a first step to predict soybean yield of Illinois using CROPGRO-Soybean model, genetic coefficients representative for each soybean maturity group (MG I~VI) were estimated through sowing date experiments using domestic and foreign cultivars with diverse maturity in Seoul National University Farm ($37.27^{\circ}N$, $126.99^{\circ}E$) for two years. The model using the representative genetic coefficients simulated the developmental stages of cultivars within each maturity group fairly well. Soybean yields for the grids of $10km{\times}10km$ in Illinois state were simulated from 2,000 to 2,011 with weather data under 18 simulation conditions including the combinations of three maturity groups, three seeding dates and two irrigation regimes. Planting dates and maturity groups were assigned differently to the three sub-regions divided longitudinally. The yearly state yields that were estimated by averaging all the grid yields simulated under non-irrigated and fully-Irrigated conditions showed a big difference from the statistical yields and did not explain the annual trend of yield increase due to the improved cultivation technologies. Using the grain yield data of 9 agricultural districts in Illinois observed and estimated from the simulated grid yield under 18 simulation conditions, a multiple regression model was constructed to estimate soybean yield at agricultural district level. In this model a year variable was also added to reflect the yearly yield trend. This model explained the yearly and district yield variation fairly well with a determination coefficients of $R^2=0.61$ (n = 108). Yearly state yields which were calculated by weighting the model-estimated yearly average agricultural district yield by the cultivation area of each agricultural district showed very close correspondence ($R^2=0.80$) to the yearly statistical state yields. Furthermore, the model predicted state yield fairly well in 2012 in which data were not used for the model construction and severe yield reduction was recorded due to drought.

• Journal of the Korean Institute of Landscape Architecture
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• v.46 no.1
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• pp.72-85
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• 2018

This study focused on cases that led sustainable urban development through the construction and utilization of organic greenery systems linking green spaces of urban peripheries with metropolitan areas. To that end, Berlin - Brandenburg's regional parks in Germany and Milan's Raggi Verdi, a radial green axis project, in Italy were selected for analysis as case studies. As frameworks for this analysis, this study has established existing infrastructure accessibility and linkage, recycling and cooperative management. The results of the case study analysis are as follows: First, the specialized spatial strategy based on the individuality of the green space outside the city rather than a uniform landscape was used as the foundation of the sustainable development plan. Second, physical linkage from the center of the city to the periphery contributed to the sustainable development of the overall metropolis by improving the economic value of the surrounding area as well as ecological and environmental values. Third, the central management system was established to reduce the administrative inconvenience caused by multiple administrative districts in the green space of urban periphery. The implications of applying the above results to Seoul, Korea are as follows. First, it is necessary to establish a differentiation strategy by re-establishing the identity of a green landscape in the urban periphery, because the green spaces of Seoul's periphery are dispersed and mostly have a repetitious mountain landscape. Also, it is necessary to actively link peripheral mountains and urban green areas to create ecological value and economic value, and ultimately to help the sustainable development of the city. Finally, building an integrated management system is required to solve fragmented green space management departments in most of the urban periphery's green spaces. In conclusion, this study shows the significant possibility that the sustainable development of a metropolis can be derived from the utilization, linkage, and management of the green space in the urban peripheries, which is extraordinary compared to normal centralized urban development.

• Korean Journal of Environment and Ecology
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• v.30 no.6
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• pp.939-961
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• 2016

For effective conservation of endangered wild plants, it is necessary to understand their interactions with environmental factors in each habitat together with life traits of target species. First, the characteristics of their distribution were investigated followed by their monitoring for 4 years focusing on the habitats in the lagoon. Also, their life traits were compared including production of hibernacles, fruits, and seeds by the soil fertilization and light intensities. Next, the information on the species was secured by germination experiment using the generated seeds from the cultivation experiment. The habitat of Glaux maritima var. obtusifolia Fernald in Korea was located in the rear edge of the worldwide distribution and its four habitats were isolated and distributed far away each other. Two of them were located in small salt-marsh and fine sand estuaries formed in the rocky area of the seashore, and the other two were inhabited with the sandy soil in the lagoon which was connected by river-mouth to the sea. Glaux maritima var. obtusifolia Fernald tends to be distributed in the sites where the establishment and growth of the competitor were inhibited by salinity, periodic flooding, and lower layer of the soil to extend a roots. It maintained its population by recruitments of hibernacles and seedling. The production of hibernacle was assumed to be affected by the particle consist of the sand together with organic matters in the soil. Seedling recruitment was observed only in the salt-marsh area located in the rear sites of sand ridge where was the shore of the lagoon. Glaux maritima var. obtusifolia Fernald was observed to have different threatening factors by each population. Its population in Pohang seemed the sedimentation of fine sand which affected the recruitment of hibernacles had been eroded due to the construction of the coastal road. The population in Ulsan appeared rapid expansion of competitor and reduction of its distribution area due to the interruption of eluted water supplied to the habitat. On the other hand, the habitat in the lagoon maintained the population relatively stable. Especially, the population in Songji-ho was determined to be the most stable one. To sustain the population of Glaux maritima var. obtusifolia Fernald distributed in the lagoon, it is suggested that the wide ranged scale of conservational activities is necessary to maintain the mechanisms including the entrance of seawater which belongs to the lagoon, and periodic flooding.

• Journal of Wetlands Research
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• v.17 no.1
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• pp.53-61
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• 2015

Habitat creation for endangered species Menyanthes trifoliata L. using planting module represents a habitat type such as the rhizome grows horizontally to open water at the margin of the lake. The objectives of this mesocosm experiment are habitat creation with easy construction and low management effort, and to investigate the potential of providing a habitat for aquatic macroinvertebrates. Planting modules had three different substrates of bed soil, perlite and K-SOIL (artificial lightweight soil using bottom ash). These modules were established in two different size of the tub($1170{\times}2250{\times}300mm^3$, $900{\times}1360{\times}190mm^3$). According to the monitoring results, number of leaves and coverage of M. trifoliata showed significant difference with substrate and tub size. The number of leaves showed similar growth responses in bed soil (mean 22.979) and K-SOIL (mean 28.042) substrates but growth was poor in perlite substrate (mean 1.667). The number of leaves in the large tub was more than small tub (p=0.015). Similar responses were obtained with the coverage, the length of rhizome and the number of rhizome in M. trifoliata. A total of 21 taxa of aquatic macroinvertebrates including 1,145 individuals was found in the mesocosm. The Shannon diversity index and colonization index in the mesocosm were similar to the previous studies. These results suggest that the experimental mesocosm could provide sufficient habitats for aquatic macroinvertebrates. If planting modules use bed soil or K-SOIL by planting substrate, establish that taking into account open water surfaces for M. trifoliata growth and manage about 30cm of water depth control, then habitat creation for M. trifoilata will be successful.