• Korean Journal of Remote Sensing
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• v.37 no.3
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• pp.577-589
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• 2021

Drone mapping systems can be applied to many fields such as disaster damage investigation, environmental monitoring, and construction process monitoring. To integrate individual sensors attached to a drone, it was essential to undergo complicated procedures including time synchronization. Recently, a variety of composite sensors are released which consist of visual sensors and GPS/INS. Composite sensors integrate multi-sensory data internally, and they provide geotagged image files to users. Therefore, to use composite sensors in drone mapping systems, mapping accuracies from composite sensors should be examined. In this study, we analyzed the mapping accuracies of a composite sensor, focusing on the data acquisition area and pre-calibration effect. In the first experiment, we analyzed how mapping accuracy varies with the number of ground control points. When 2 GCPs were used for mapping, the total RMSE has been reduced by 40 cm from more than 1 m to about 60 cm. In the second experiment, we assessed mapping accuracies based on whether pre-calibration is conducted or not. Using a few ground control points showed the pre-calibration does not affect mapping accuracies. The formation of weak geometry of the image sequences has resulted that pre-calibration can be essential to decrease possible mapping errors. In the absence of ground control points, pre-calibration also can improve mapping errors. Based on this study, we expect future drone mapping systems using composite sensors will contribute to streamlining a survey and calibration process depending on the data acquisition circumstances.

• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.4
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• pp.237-250
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• 2023

Orthophotos and DEMs were generated by UAV-based aerial photogrammetry and an attempt was made to apply them to detailed investigations for the production of flood traces. The cultivated area located in Goa-eup, Gumi, where the embankment collapsed and inundated inundation occurred due to the impact of 6th Typhoon Sanba in 2012, was selected as rhe target area. To obtain optimal accuracy of UAV photogrammetry performance, the UAV images were taken under the optimal placement of 19 GCPs and then point cloud, DEM, and orthoimages were generated through image processing using Pix4Dmapper software. After applying CloudCompare's CSF Filtering to separate the point cloud into ground elements and non-ground elements, a finally corrected DEM was created using only non-ground elements in GRASS GIS software. The flood level and flood depth data extracted from the final generated DEM were compared and presented with the flood level and flood depth data from existing data as of 2012 provided through the public data portal site of the Korea Land and Geospatial Informatix Corporation(LX).

• Journal of Oral Medicine and Pain
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• v.34 no.4
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• pp.397-407
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• 2009

The aim of the study was to evaluate psychosocial impact of non-dental chronic orofacial pain (OFP) on daily living using the graded chronic pain (GCP) scale. It is also investigated the clinical profile such as demographics, event related to initiation of OFP and prior treatments for patients. During previous 6 months since September 2008, 572 patients (M:F=1:1.5, mean age=34.7 years) with non-dental OFP attended university-based specialist orofacial pain clinic (Dankook University Dental Hospital, Cheonan) to seek care although 63% of them already experienced related treatment for their OFP problem. They visited the most frequently general dental practitioner and orthopedic doctors due to their pain problem and medication was the most commonly employed modality. Most of the patients (89.2%) had TMD and the most common related event to initiation of their pain was trauma, followed by dental treatment. Almost half of the patients (46%) suffered from chronic pain(${\geq}6\;M$) and 40% of them exhibited relatively high disability due to chronic OFP. GCP pain intensity and disability days were significantly different for age and diagnosis (p<0.05) but not for gender and duration. GCP grades were affected by all the factors including gender, age, pain duration and diagnosis.(p=0.000) Female gender, elders, and long lasting pain were closely related to high disability. The patients with neuropathic Pain and mixed OFP rather than TMD were graded as being highly disabled. Conclusively, a considerable percentage of chronic OFP patients reports high pain-related disability in their daily, social and work activity, which suggest a need for psychosocial support and importance of earlier referral for appropriate diagnosis and tailored management.