• Korean Journal of Remote Sensing
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• v.17 no.3
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• pp.231-242
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• 2001

In 2-pass differential SAR interferometry(DInSAR), the topographic phase signature can be removed by using a digital elevation model(DEM) to isolate the contribution of deformation from interferometric phase. This method has an advantage of no unwrapping process, but applicability is limited by precision of the DEM used. The residual phase in 2-pass differential interferogram accounts for error of DEM used in the processing provided that no actual deformation exits. The objective of this paper is a preliminary study to improve DEM precision using low precision DEM and 2-pass DInSAR technique, and we applied the 2-pass DInSAR technique to Asan area. ERS-1/2 tandem complex images and DTED level 0 DEM were used for DInSAR, and the precision of resulting DEM was estimated by a 1:25,000 digital map. The input DEM can be improved by simply adding the DInSAR output to the original low precision DEM. The absolute altitude error of the improved DEM is 9.7m, which is about the half to that of the original DTED level 0 data. And absolute altitude error of the improved DEM is better than that from InSAR technique, 15.8m. This approach has an advantage over the InSAR technique in efficiently reducing layover effects over steep slope region. This study demonstrates that 2-pass DInSAR can also be used to improve DEM precision.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.3
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• pp.293-301
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• 2011

The ionospheric delay is the largest error source in GPS positioning after the SA effect has been turned off in May, 2000. In this study, we used 44 permanent GPS stations being operated by National Geographic Information Institute (NGII) to estimate Total Electron Content (TEC) based on pseudorange measurements phase-leveled by a linear combination with carrier phases. The Differential Code Bias (DCB) of GPS satellites and receivers was estimated and applied for an accurate estimation of the TEC. To validate our estimates of DCB, changes of TEC values after DCB application were investigated. As a result, the RMS error went down by about an order of magnitude; from 35~45 to 3~4 TECU. After the DCB correction, ionospheric TEC maps were produced at a spatial resolution of $1^{\circ}{\times}1^{\circ}$. To analyze the effect of the number of sites used for map generation on the accuracy of TEC values, we tried 10, 20, 30, and 44 stations and the RMS error was computed with the Global Ionosphere Map as the truth. While the RMS error was 5.3 TECU when 10 sites are used, the error reduced to 3.9 TECU for the case of 44 stations.

• Journal of Korea Technology Innovation Society
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• v.13 no.4
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• pp.680-699
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• 2010

In this paper, we attempted to analysis and track dynamic properties of the interdisciplinary relationship between scientific research areas in energy field using bibliometric analysis. We created network maps with SCs (subject categories) defined from $WoS^{\circledR}$ (Web of Science, Thomson Scientific ISI, Philadelphia, USA) using co-occurrence analysis method in order to identify overall disciplines directly linked with energy fields and investigate the change of interaction between SCs as a function of time. From the results of this study, thermodynamics, fuels, chemistry/chemical engineering, and electrochemistry have differentiated into more specific disciplines while the strength of interaction with energy field gradually has increased. Meanwhile, "nuclear physics" was developed to "nuclear science & technology" toward applicable target sector and also the interaction of "environmental science" with "energy generation area" among various energy disciplines recently showed the radical increase as compared with the values of 4 years ago. Finally, through combinative reviews of today's energy policy established by South Korea government, this study will give a help for keeping up with national energy agenda meeting the diverse characteristics of academic disciplines of energy field. In addition, our results support that the use of such network analysis based on bibliometric analysis to discern shifts in academic R&D strategies and target sectors.

• Korean Journal of Remote Sensing
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• v.21 no.4
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• pp.287-302
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• 2005

Digital Elevation Models (DEMs) were generated by ERS-l/2 and JERS-1 SAR interferometry in Daejon area, Korea. The quality of the DEM's was evaluated by the Ground Control Points (GCPs) in city area where GCPs were determined by GPS surveys, while in the mountain area with no GCPs, a 1:25,000 digital map was used. In order to minimize errors due to the inaccurate satellite orbit information and the phase unwrapping procedure, a Differential InSAR (DInSAR) was implemented in addition to the traditional InSAR analysis for DEM generation. In addition, DEMs from GTOPO30, SRTM-3, and 1:25,000 digital map were used for assessment the resolution of the DEM generated from DInSAR. 5-6 meters of elevation errors were found in the flat area regardless of the usage and the resolution of DEM, as a result of InSAR analyzing with a pair of ERS tandem and 6 pairs of JERS-1 interferograms. In the mountain area, however, DInSAR with DEMs from SRTM-3 and the digital map was found to be very effective to reduce errors due to phase unwrapping procedure. Also errors due to low signal-to-noise ratio of radar images and atmospheric effect were attenuated in the DEMs generated from the stacking of 6 pairs of JERS-1. SAR interferometry with multiple pairs of SAR interferogram with low resolution DEM can be effectively used to enhance the resolution of DEM in terms of data processing time and cost.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.2
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• pp.137-143
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• 2008

The spherical glasses lenses are typically classified into two groups such as (+) diopter lens and (-) diopter lens by the refractive power index. The thermal deformation of a lens is occurred by external heat source and is changed respected to the diopter of a lens. In this paper, the thermal deformation of spherical glasses lenses were quantitatively measured by using ESPI (electronic speckle pattern interferometry) which has an advantage that the non-contact, non-destructive and precise deformation measurement is available due to the coherency characteristic. The temperature changes were measured by IR camera. It makes experiments over 14 types of the plastic glasses lenses. From the results, it was confirmed that the larger diopter lens showed the less thermal deformation in case of the (+) diopter lens. On the other hand, the thermal deformation of the (-) diopter lens was measured with uniform pattern when the same temperature changes were applied. Also, it was found that the thermnal deformation of the (+) diopter lens is less than that of the (-) diopter lens. Therefore, it is expected that when the thermal deformation is occurred to the various types of the lens, the variation of the focal length caused by the thermal distortion of a lens would be measured quantitatively.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.6
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• pp.533-542
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• 2020

This study proposes the logical data model design of a spatial data model that complies with international standards for the waterworks of underground facilities. We conduct a preliminary study related to underground spatial data standards and data models, and review the status of the existing systems. Then, we defined the conceptual design direction of underground spatial data model based on the problems and issues. Next, we defined the terminology, classification, semantic relationships of waterworks. Next, for the conceptual design of the underground spatial data model, we defined the naming criteria for all data according to the waterworks classification. In addition, a logical model is drawn and described using UML (Unified Modeling Language) diagrams. Based on the results, it is expected that the accuracy related to underground facilities data will be improved.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.2
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• pp.193-200
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• 2006

Geographic information and surveying products are a momentous national infrastructure since it is an essential basis for land management and environmental preservation. Hence, it is necessary to set up a systematic plan and countermeasure for the upcoming unification of Korea. Otherwise there would be tremendous confusion and it will cause enormous expenses to establish the national surveying and geographical information standard. In order to show the vision of policies preparing for the unification of North and South Korea, we analyzed the case of Germany and the current status of surveying and Geographical Information in South and North Korea by taking the internet investigation, having a seminar, interviewing experts, and visiting related organizations. First of all, we should predict the change of surveying circumstances after the reunification and establish a plan that unifies laws, systems, and surveying standards of North and South Korea. We need to modify the datum point and unify the surveying product of South and North Korea in World Geodetic System. To accomplish these goals, we must make the map of Korean peninsula and neighboring nations, especially urban area of North Korea. It is considered that National Geographic Information Institute should take a major role in the unification of Korea. With these active preparations and plans, we will achieve the goals of establishing the reinforced surveying policy and minimizing the reunification expenses.

• Korean Journal of Remote Sensing
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• v.38 no.5_1
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• pp.447-460
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• 2022

It is well known that satellite synthetic aperture radar interferometry (InSAR) has been widely used for the observation of surface displacement owing to earthquakes, volcanoes, and subsidence very precisely. In wetlands where vegetation exists on the surface of the water, it is possible to create a water level change map with high spatial resolution over a wide area using the InSAR technique. Currently, a number of imaging radar satellites are in operation, and most of them support a ScanSAR mode observation to gather information over a large area at once. The Cienaga Grande de Santa Marta (CGSM) wetland, located in northern Colombia, is a vast wetland developed along the Caribbean coast. The CGSM wetlands face serious environmental threats from human activities such as reclamation for agricultural uses and residential purposes as well as natural causes such as sea level rise owing to climate change. Various restoration and protection plans have been conducted to conserve these invaluable environments in recognition of the ecological importance of the CGSM wetlands. Monitoring of water level changes in wetland is very important resources to understand the hydrologic characteristics and the in-situ water level gauge stations are usually utilized to measure the water level. Although it can provide very good temporal resolution of water level information, it is limited to fully understand flow pattern owing to its very coarse spatial resolution. In this study, we evaluate the L-band ALOS-2 PALSAR-2 ScanSAR mode to observe the water level change over the wide wetland area using the radar interferometric technique. In order to assess the quality of the interferometric product in the aspect of spatial resolution and coherence, we also utilized ALOS-2 PALSAR-2 stripmap high-resolution mode observations.

• Cartoon and Animation Studies
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• s.16
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• pp.1-20
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• 2009

This paper explores the research trends in the area of the comics studies in Korea. In this article, the 664 academic articles are examined in terms of the characteristics of the researchers, the field of comics studies, the research theme and the research methodology. This study is on the basis of the recognition that there have been no consensus on what the core essence of comics studies is. As a result, there are a few articles on the academic identity of the comics studies. The comics studies have not consider the distinctive characteristics of the Korean comics significantly. In Korea, over 50% of the academic articles on the comics have been published by comics scholarships in the field of pedagogy and human sciences. Since the 1990's, comics studies have started to consider the value of the comics positively. The comics text studies also have increased since the 1990's in Korea. The comics studies on the comics policy and comics industries have been increased since 2000. The rise of comics studies is concomitant with the increased awareness of comics in Korea. The article concludes that the comics studies need to become an independent academic discipline in the future. The interdisciplinary studies on the comics is necessary to study the diverse aspects of the comics. In addition, the infrastructure for the comics studies should be established in order to improve the comics studies.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.29 no.4
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• pp.182-197
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• 2011

This research was carried out to investigate the history and development process of the Bansu(泮水) which appeared uniquely at the Chinese 'temple-school(廟學)', Confucian schools as the common and necessary facility through the literature reviews and field surveys. The earliest record about the Bansu was shown in "The Book of Odes(詩經)". Originally Bansu was the water system which flowed near the 'Banpalace(泮宮)', but, in the following time, Bansu has become the symbol of the school which was built by the feudal lords and a very important element in the temple-school landscape. Temple-schools were started at Song(宋) Dynasty and at that time there was no certain form of Bansu, just the natural water course near the structure. Until Ming Dynasty, the "Picture of the Feudal lords' Ban-su" in the book "Samjedohoe(三才圖會)" that compiled by Wang-Xi(王圻), the form of Bansu was appeared to be transformed as the half-round pond. And the half-round pond as called Banji(泮池) of today's form was all rebuilt after Ming Dynasty. The half-moon pond appeared at the private houses, shrines, temples and villages were influenced by the book. From this research we can get the conclusions that Banji seemed one of the sacred one and used in the space arrangement formally for the various functions. This research has found the cultures of half-moon ponds which were used uniquely in China.