• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.8
• /
• pp.719-727
• /
• 2008

A 3-D compressible Navier-Stokes solver using overlapped grids is developed to predict a flow-field around a hovering rotor. The flow solver is verified by a parametric study with the grid spacing of wake grid, spatial accuracy and turbulence model. Computations are performed with different Chimera grid systems. Computational results are compared with the experimental data of Caradonna et al. for both blade loading and the tip vortex behavior. Numerical results show good agreements with experiments for the distribution of surface pressure and tip vortex behavior. Pressure distributions over the blade have marginal differences for different numerical methods, whereas large discrepancies are seen in the prediction of the wake behavior. Results unexpectedly show that the vortex strength from an automated cut-paste Chimera grid is weaker than that from the conventional Chimera grid.

• Journal of Environmental Impact Assessment
• /
• v.21 no.1
• /
• pp.25-39
• /
• 2012

This study was aimed to assess the effects of additional installation of two different types of weirs, one is a curtain-type weir and another is a submerged-type weir, on the control of algal growth in Daechung Reservoir. A two-dimensional(2D) coupled hydrodynamic and eutrophication model that can accommodate vertical movement of the curtain weir following the water surface variations was verified using field data obtained in two distinctive hydrological years; dry(2008) and wet(2010). The model adequately simulated the temporal and spatial variations of water temperature, nutrients and algal(Chl-a) concentrations during the periods. The effectiveness of curtain weir on the control of algal bloom was evaluated by applying the model to 2001(dry year) and 2010 assuming 6 different scenarios according to installation locations. The curtain weirs that already installed at 3, 5, 7 sites(scenario C-2) showed significant effect on the control of algal growth in the reservoir; the reduction rates of algal concentration were placed in the range of 7.5~31.5% and 9.1~44.9% for 2001 and 2010, respectively. However the simulation results revealed that additional installation of curtain weirs(scenario C-3~C-6) in the bay area (choosori) have marginal effect. The effectiveness of submerged weir was evaluated against 2010 assuming 7 different scenarios according to installation locations, but all scenarios(S-1~S-7) showed neglectable or negative effect on the control of algal growth.

• Ecology and Resilient Infrastructure
• /
• v.8 no.4
• /
• pp.266-272
• /
• 2021

Water friendly space refers to a place designated to plan and manage spaces for residents Water friendly activities. Efficient management of river Water friendly parks requires automated GIS data and DB construction of the water friendly facilities. Object-based classification using drone images or aerial images is attracting attention as an efficient means to acquire 3D spatial information in the country. To remove the miscellaneous image included in the extracted outline, a linear simplification of the outline is required, and it is difficult to apply manually, so various automation methods have been developed to overcome this, and among them, the most widely studied and utilized is the linear simplification method. In this study, the suitability of linear simplification algorithms such as Douglas-Peucker, Visvalingam-Whyatt, and Bend-simplify algorithms for the geometric shape of hydrophilic facilities was determined.

• Journal of Biomedical Engineering Research
• /
• v.25 no.5
• /
• pp.323-328
• /
• 2004

The development of group-specific tissue probability maps (TPM) provides a priori knowledge for better result of cerebral tissue classification with regard to the inter-ethnic differences of inter-subject variability. We present sequential procedures of group-specific TPM and evaluate the age effects in the structural differences of TPM. We investigated 100 healthy volunteers with high resolution MRI scalming. The subjects were classified into young (60, 25.92+4.58) and old groups (40, 58.83${\pm}$8.10) according to the age. To avoid any bias from random selected single subject and improve registration robustness, average atlas as target for TPM was constructed from skull-stripped whole data using linear and nonlinear registration of AIR. Each subject was segmented into binary images of gray matter, white matter, and cerebrospinal fluid using fuzzy clustering and normalized into the space of average atlas. The probability images were the means of these binary images, and contained values in the range of zero to one. A TPM of a given tissue is a spatial probability distribution representing a certain subject population. In the spatial distribution of tissue probability according to the threshold of probability, the old group exhibited enlarged ventricles and overall GM atrophy as age-specific changes, compared to the young group. Our results are generally consistent with the few published studies on age differences in the brain morphology. The more similar the morphology of the subject is to the average of the population represented by the TPM, the better the entire classification procedure should work. Therefore, we suggest that group-specific TPM should be used as a priori information for the cerebral tissue classification.

• Journal of the Korean GEO-environmental Society
• /
• v.22 no.2
• /
• pp.35-39
• /
• 2021

Photogrammetry using drone can produce high-resolution ortho image and acquire high-accuracy 3D information, which is useful. Therefore, this study attempted to determine the possibility of using drone-photogrammetry in park construction by producing a topographic map using drone-photogrammetry and analyzing the problems and accuracy generated during production. For this purpose, we created ortho image and DSM (digital surface model) using drone images and created topographic status map by vectorizing them. Accuracy was compared based on topographic status map by GPS (global positioning system) and TS (total station). The resulting of analyzing mean of the residuals at check points showed that 0.044 m in plane and 0.066 m in elevation, satisfying the tolerance range of 1/1,000 numerical maps, and result of compared lake size showed a difference of about 4.4%. On the other hand, it was difficult to obtain accurate height values for terrain in which existed vegetation when producing the topographic map, and in the case of underground buried objects, it is not possible to confirm it in the image, so direct spatial information acquisition was necessary. Therefore, it is judged that the topographic status map using drone photogrammetry can be efficiently constructed if direct spatial data acquisition is achieved for some terrain.

• Korean Journal of Remote Sensing
• /
• v.35 no.2
• /
• pp.337-342
• /
• 2019

This letter describes the development of WRI (Wildfire Risk Index) using GDAPS (Global Data Assimilation and Prediction System) and satellite data, and its application to the Goseong-Sokcho and Gangneung-Donghae wildfires in April 4, 2019. We made sure that the proposed WRI represented the change of wildfire risk of around March 19 and April 4 very well. Our approach can be a viable option for wildfire risk monitoring, and future works will be necessary for the utilization of GK-2A products and the coupling with the wildfire prediction model of the Korea Forest Service.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.15 no.1
• /
• pp.39-67
• /
• 1987

The purpose of this thesis is to suggest objective basic data for the environmental design through the quantitative analysis of the visual quality included in the physical environment of forest landscape. For this, landscape values of forest landscape have been evaluated by using the Iverson method, the images structure of forest landscape's main utilizing space have been analysed by the factor analysis algorithm, degree of visual preferences have been pleasured mainly by questionnaries and SBE method, and finally these thesis can be summarized as fallow LCP with high values of Iverson factors I and IV yield high landscape value. Specifically, Iverson factor IV has been found to play the dominant. For all experimental points, significant seasonal variations in S.D. scale values have been observed. In natural parks, where artificial structures are complementary to the natural landscape, main factors of image are S.D. scales such as the visual sequence, the formal simplicity of structures, the emphasis, the unification of heterogeneous factors and the assimilation. Factors covering the spatial image of natural parks have been found to be the overall evaluation, the individual characteristics, the tidiness, the potentiality, the dignity, the intimacy and the space volume. For all seasons, factors such as the individual characteristics, the dignity, the tidiness, the potentiality, yield high factor scores. As for factors determining the degree of visual preference, variables such as the summit, the skyline, rocks, the water and the degree of natural destruction by artificial structures yield high values for all seasons.

• Asian Pacific Journal of Cancer Prevention
• /
• v.17 no.3
• /
• pp.1293-1297
• /
• 2016

Cholangiocarcinoma (CCA) is a serious problem in Thailand, particularly in the northeastern and northern regions. Database of population at risk are need required for monitoring, surveillance, home health care, and home visit. Therefore, this study aimed to develop a geographic information system (GIS) database and Google map of the population at risk of CCA in Mueang Yang district, Nakhon Ratchasima province, northeastern Thailand during June to October 2015. Populations at risk were screened using the Korat CCA verbal screening test (KCVST). Software included Microsoft Excel, ArcGIS, and Google Maps. The secondary data included the point of villages, sub-district boundaries, district boundaries, point of hospital in Mueang Yang district, used for created the spatial databese. The populations at risk for CCA and opisthorchiasis were used to create an arttribute database. Data were tranfered to WGS84 UTM ZONE 48. After the conversion, all of the data were imported into Google Earth using online web pages www.earthpoint.us. Some 222 from a 4,800 population at risk for CCA constituted a high risk group. Geo-visual display available at following www.google.com/maps/d/u/0/edit?mid=zPxtcHv_iDLo.kvPpxl5mAs90&hl=th. Geo-visual display 5 layers including: layer 1, village location and number of the population at risk for CCA; layer 2, sub-district health promotion hospital in Mueang Yang district and number of opisthorchiasis; layer 3, sub-district district and the number of population at risk for CCA; layer 4, district hospital and the number of population at risk for CCA and number of opisthorchiasis; and layer 5, district and the number of population at risk for CCA and number of opisthorchiasis. This GIS database and Google map production process is suitable for further monitoring, surveillance, and home health care for CCA sufferers.

• Journal of Korean Society for Geospatial Information Science
• /
• v.23 no.1
• /
• pp.3-14
• /
• 2015

As buildings in the downtown area, such as the complex building connected to the skyscraper and the underground facility, have become large and complex, the range of target domain of the space information service is rapidly expanding to the interior space; it is considered that this change will create various demands of service such as the indoor geospatial information base safety, the management of facility, and the interior navigation in the future, along with spread of mobile devices and development of IT technology. As for the indoor geospatial information, however, there is no certification standard of the established indoor geospatial information data quality, so preparing the certification standard is urgent. Thus, this study reviewed foreign and domestic research cases and prepared measures for quality verification of the indoor geospatial information to conduct a verification test of the Yeongdeungpo Station indoor geospatial information, established in 2014. As a result, through the verification test of the method and standard of the indoor geospatial information quality certification suggested by this research, it was identified that the uniform and higher quality data could be classified, and the types of error high frequently occurring could be investigated. These results are expected to be utilized as the basic data for establishing quality certification system for the indoor geospatial information in the future.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.40 no.6
• /
• pp.47-59
• /
• 2012

In this study, species and seasonal scenery image were made using 3D simulation modeling to evaluate emotional image of street trees in the roads cape. Study site are set in Tongdaeguro, located in Daegu Metropolitan City and Cedrus deodara, Metasequoia glyptostroboides, Liriodendron tulipifera L., and Zelkova serrata were selected to evaluate the species. In the survey result, it appears that Zelkova serrata is the highest preference for summer landscape and Metasequoia glyptostroboides is the highest preference for fall and winter landscape. With regard to the factor analysis, in order to derive emotional evaluation factor, aesthetic factor, perception factor, individuality factor, natural factor, and spatial factor were derived and aesthetic factor is the greatest impact for preference common in all seasons. Preference and positive emotional image of Metasequoia glyptostroboides is evaluated as the highest in the winter and the aesthetic factor score reduction is less than the other species. This study will be used in offering objective data and landscape planning for making comfortable roads cape through the quantitative evaluation as each species and seasonal changes.