The main objective of this paper is to seek to find the best map projection for a map of “Korea and Its Vicinity.” To that end, a review on pre-existing maps for the region and some selection guidelines is undertaken. A research strategy is established through an intensive examination on various methods for distortion analysis. Finally, a GIS-based projection distortion analysis is conducted and the final selection is made based on it. Main findings are as follows. First, four candidates are selected; Lambert conformal conic, Albers equivalent conic, Lambert azimuthal equivalent, and Azimuthal equidistant projections. Second, it is acknowledged that a research scheme for projection distortion analysis should be predicated on the local distortion indictors at the infinitesimal scale and that local distortion values are virtually generated in order to be used for visualization and statistics calculation. Third, the PDAT is chosen as the research platform in which a GIS environment for the projection distortion analysis is provided. Based on all the results from the PDAT analysis, the final decision is made for the best projection; Lambert azimuthal equivalent projection. This study may provide important implications in discussing on the best projection for a map of Korea.
Many foreign geographical names are still found in internet-based maps such as Google Earth and reliable place name database such as GEONet Names Server. Those names are not currently used and are also unfamiliar to Korean residents. Those foreign names are most frequently found in coastal geographical names or undersea feature names. If we can trace historical origins of those names, it will be very important in terms of standardization of geographical names, of which one proper name should be given to each geographical feature. Western ships frequently visited Korean waters from the early 18th century; some were looking for trading opportunities, missionary purposes, or simply chasing whales. Both language barriers and isolation policy of Korean government kept western vessels acquiring proper Korean geographical names and they charted what they surveyed in their own language. Further studies on the role of Russia, Netherlands and USA which had not been dealt with in depth are necessary to fully understand the role of western countries.
This study proposes a hierarchical zooming technique that can be used in the smart devices supporting touch interface. Prototype web map is implemented based on HTML5. Characteristics of the proposed technique are identified. A hierarchical zooming technique is applicable for exploring the multi-level choropleth maps focusing on a specific region. A proposed technique is supposed to be a new geovisual analytics technique for exploring geographical pattern.
Satellite image classification is one of the useful methodologies for land-cover (land-use) map generation. But prevailing supervised classification results vary according to training areas and classifiers. Meanwhile, vegetation indices originally developed for testing vital degree of vegetations are modified up to 20 kinds and NDBI (Normalized Difference Built-up Index), NDVI (Normalized Difference Vegetation Index) and MNDWI (Modified Difference Water Index) are suitable for detecting built-up area, vegetation area, and water area respectively. In this research, Landsat TM satellite images are transformed into 3 bands generated using NDBI, NDVI and MNDWI equation and then unsupervised classification method is used in classification. The proposed method can conveniently classify the image because the method doesn't require training area selection and statistical assumptions. Accuracy differences using reference data are about 2%. Because the proposed method does not need statistical requirements such as sample distribution and class divergence and is quite simple, it will be useful in built-up area extraction.
Current web-based GIS (geographic information system) requires a more effective way of managing and distributing large time-series dataset. This paper describes a method for improving the interoperability and extensibility of web GIS services by implementing an Open API (application programming interface) for time- series raster database on the REST (Representation State Transfer) basis. We first implemented spatio-temporal operations for time-series raster dataset by creating temporal objects and temporal functions within a DBMS (database management system) which can be combined with the existing spatial objects and spatial functions of the DBMS. We employed the REST communication for a lighter request-response structure between client and server, and defined URI (unified resource identifier) interfaces for building spatio-temporal query statements. Our Open API can be consumed by any client in the identical ways irrespective of their development environments so that all computer languages supporting HTTP (Hypertext Transfer Protocol) are compatible with the Open API. For the feasibility tests of our Open API, we carried out spatio-temporal queries and the 3-D visualization of time-series raster dataset using Google Earth Web Plugin and WebGL (Web Graphics Library).
The new address system based on road name in Korea has been settled from 2012. In addition, national basic district as a smallest unit region of nation has also been notified in 2012 and is envisioned to be utilized in earnest from 2014. It is needed for us to construct an integrated data by connecting address data based on road name with national basic district data because road, address, and national basic district are closely interconnected. In this study, we propose data model of national basic district by integrating the information of national basic district with the address based on road name and try to derive some initiatives and possibility of its application by implementing this model in a study area. We have analyzed not only data model of foreign countries which use the address system based on road name, but also current data model of the address system and the national basic district in Korea. Based on this analysis, we have designed data model which can include all kinds of linear information related to road, address and district and have implemented this model in Seodaemoon-gu as a sample case. As a result of the implementation, we have confirmed three folds: First, it is necessary to cleanse the centerline of road features in order to prevent that the road segments are divided into tiny sections. Second, it is needed not to assign the address attribute for the subordinate road segment. Finally, since there is an example that subordinate road segments are used in the delimination of national basic district, it is needed to input related districts information after distinguishing the left side and the right side of the subordinate road segments even though the address attributes are not assigned.
Political redistricting problems are the way of aggregating a set of population units into contiguous geographical area with redistricting criteria. Political redistricting problems are very difficult because they can be lead to political debate because the drafter may take part in redistricting process with subjective opinions. Also, these problems are complicated because the number of feasible redistricting plans is exponentially increased with the problem size. Especially, US constitution requires that the congressional district should be redrawn to make populations strictly equal and make population units successfully contiguous. However, existing approaches such as transportation problems, local search based methods and metaheuristic approaches may show the difficulty to find strict population equality redistricting plans and the inefficiency to ensure contiguity. The purpose of this paper is to develop a heuristic approach to congressional redistricting using contiguity checking. Computational experiments show that the new heuristic shows various spatial configurations in a most strict equal population plan and finds a better plan than the official plan in terms of strict population equality. This new plan may be proposed as a new plan for the congressional plan. Also, it is significant that the research studied in the paper can be applied to the redrawing of member of the National Assembly in Korea in the near future.
The purpose of this research is to review the wayfinding methodologies theoretically based on the spatial cognition, and is to model the cognitive wayfinding method, and to explore the significant differences with respect to the structure of the pass network by comparing optimized paths. There have been various kinds of researches and systems developed, but the proper theoretical review in terms of spatial cognition was not implemented. In the real world, limited wayfinding behaviors are likely to be related to lack of consideration of spatial cognition. The wayfinding based on spatial cognition is the process to be implemented with the interaction of the surrounding environment. Based on the theoretical review, this paper addresses how the cognitive paths are constructed based on the direction and distance perceptions and comparatively analyzes the differences between the cognitive and the optimized shortest paths, in case of Gwan-ak Campus, Seoul National University. As a result of analysis, it showed that there were the significant differences of travel distances between the cognitive and shortest paths and were significantly influenced by the configuration and structure of the pass network. In addition, we found some nodes making important decisions of the wayfinding would be utilized as critical points providing additional spatial information to improve wayfinding efficiency.