• Korean Journal of Remote Sensing
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• v.31 no.5
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• pp.371-384
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• 2015

Although GOCI has potential for land surface monitoring, there have been only a few cases for land applications. It might be due to the lack of reliable land products derived from GOCI data for end-users. To use for land applications, it is often essential to provide cloud-free composite over land surfaces. In this study, we proposed a cloud detection method that was very important to make cloud-free composite of GOCI reflectance and vegetation index. Since GOCI does not have SWIR and TIR spectral bands, which are very effective to separate clouds from other land cover types, we developed a multi-temporal approach to detect cloud. The proposed cloud detection method consists of three sequential steps of spectral tests. Firstly, band 1 reflectance threshold was applied to separate confident clear pixels. In second step, thick cloud was detected by the ratio (b1/b8) of band 1 and band 8 reflectance. In third step, average of b1/b8 ratio values during three consecutive days was used to detect thin cloud having mixed spectral characteristics of both cloud and land surfaces. The proposed method provides four classes of cloudiness (thick cloud, thin cloud, probably clear, confident clear). The cloud detection method was validated by the MODIS cloud mask products obtained during the same time as the GOCI data acquisition. The percentages of cloudy and cloud-free pixels between GOCI and MODIS are about the same with less than 10% RMSE. The spatial distributions of clouds detected from the GOCI images were also similar to the MODIS cloud mask products.

• Korean Journal of Remote Sensing
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• v.34 no.2_2
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• pp.431-437
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• 2018

We analyzed the feasibility of detecting wave gliders moving on the sea surface using SAR images. For the experiment, a model was constructed and placed on the sea using a towing ship before and after the satellite observation time. In the acquisition of KOMPSAT-5 image, high resolution SAR data of spotlight mode was collected considering the small size of wave glider. As a result of the backscattering intensity analysis around the towing ship along with wave glider, several scattering points away from the ship were observed, which are not strong but clearly distinguished from the surrounding clutter values. Considering the distance from the center of the ship, it seems to be a signal by the wave glider. On the other hand, it is confirmed that the wave glider can be detected even at the very low false alarm rate ($10^{-6}$) of the target detection using CFAR. Although the scatter signal by the wave glider could be distinguished from the surrounding ocean clutter in the high resolution SAR image, further research is needed to determine if actual wave gliders are detected in various marine environments.

• The Korean Journal of Nuclear Medicine
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• v.29 no.1
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• pp.48-53
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• 1995

This study investigates a simple mathematical model for the quantitative estimation of regional myocardial blood flow in experimental canine coronary artery thrombosis using Rb-82 dynamic myocardial positron emission tomography. The coronary thrombosis was induced using the new catheter technique by narrowing the lumen of coronary vessel gradually, which finally led to partial obstruction of coronary artery. Ten Rb-82 dynamic myocardial PET scans were performed sequentially for each experiment using our 5, 10 and 20 second acquisition protocol, respectively, and three regions of interest were drawn on the transaxial slices, one on left ventricular chamber for input function and the other two on normal and decreased perfusion segments for the flow estimation in those regions. Single compartment model has been applied to the measured sets of regional PET data, and the rate constants of influx to myocardial tissue were calculated for regional myocardial flow estimates with the three parameter fits of raw data by the Levenberg-Marquardt method. The results showed that, (1) single compartment model suggested by Kety-Schmidt could be used for the simple estimation of regional myocardial blood flow, (2) the calculated regional myocardial blood flow estimates were dependent on the selection of input function, which reflected partial volume effect and left ventricular wall motion, and (3) mathematically fitted input and tissue time activity curves were more suitable than the direct application of the measured data in terms of convergence.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.2
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• pp.257-264
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• 2020

Vectorization is currently the main method in feature collection (extraction) during digital mapping using UAV-Photogrammetry. However, this method is time consuming and prone to gross elevation errors when extracted from a DSM (Digital Surface Model), because three-dimensional feature coordinates are vectorized separately: plane information from an orthophoto and height from a DSM. Consequently, the demand for stereo plotting method capable of acquiring three- dimensional spatial information simultaneously is increasing. However, this method requires an expensive equipment, a Digital Photogrammetry Workstation (DPW), and the technology itself is still incomplete. In this paper, we evaluated the accuracy of low-cost stereo plotting system, Menci's StereoCAD, by analyzing its three-dimensional spatial information acquisition. Images were taken with a FC 6310 camera mounted on a Phantom4 pro at a 90 m altitude with a Ground Sample Distance (GSD) of 3 cm. The accuracy analysis was performed by comparing differences in coordinates between the results from the ground survey and the stereo plotting at check points, and also at the corner points by layers. The results showed that the Root Mean Square Error (RMSE) at check points was 0.048 m for horizontal and 0.078 m for vertical coordinates, respectively, and for different layers, it ranged from 0.104 m to 0.127 m for horizontal and 0.086 m to 0.092 m for vertical coordinates, respectively. In conclusion, the results showed 1: 1,000 digital topographic map can be generated using a stereo plotting system with UAV images.

• Journal of Animal Environmental Science
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• v.17 no.2
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• pp.93-100
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• 2011

This study was conducted to verify the applicability of robot milking system through acquisition and analysis of model teat's position information using scanning range finder (SRF). Model teats, same size and shape as real teats, were designed to analyze the properties according to the material, distance error and angle error of the sensor. In addition, 2-dimensional distance information of each teats was obtained at same time with 4 teat models and the result were as follows. 1. In the case of the fingers on the experiment for selection of materials for teat model, the distance error was from 4.3 mm to 1.3 mm, average was 2.8 mm as a minimum record. In the case of rubber material, average distance error was 4.3 mm. So, this material was considered to be a most suitable model. 2. The distance error was maximum at 100 mm distance. The more distance increased, the less error increased up to 300 mm. Then the error increased after 300 mm and decreased again. 3. The maximum angle error of 10.1 mm was measured at $170^{\circ}$, in case of $70^{\circ}$ the error was 0.2 mm as a minimum value. There was no specific tendency to error of angle. 4. In the 2-dimensional location error for 4 teat models, distance error was 3.8 mm as minimum and 7.2 mm as maximum. The angle error was $1.2^{\circ}$ as maximum. All of errors were included within the accuracy of sensor, the robot milking system was considered to be applicable to measure the distance of teats due to the measuring velocity of SRF and the hole size of teat-cup.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.2
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• pp.211-221
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• 2012

To utilize omni-directional images acquired by a rotating line camera for indoor spatial information services, we should register precisely the images with respect to an indoor coordinate system. In this study, we thus develop a georeferencing method to estimate the exterior orientation parameters of an omni-directional image - the position and attitude of the camera at the acquisition time. First, we derive the collinearity equations for the omni-directional image by geometrically modeling the rotating line camera. We then estimate the exterior orientation parameters using the collinearity equations with indoor control points. The experimental results from the application to real data indicate that the exterior orientation parameters is estimated with the precision of 1.4 mm and $0.05^{\circ}$ for the position and attitude, respectively. The residuals are within 3 and 10 pixels in horizontal and vertical directions, respectively. Particularly, the residuals in the vertical direction retain systematic errors mainly due to the lens distortion, which should be eliminated through a camera calibration process. Using omni-directional images georeferenced precisely with the proposed method, we can generate high resolution indoor 3D models and sophisticated augmented reality services based on the models.

• Journal of Environmental Impact Assessment
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• v.27 no.3
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• pp.251-266
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• 2018

This study predicted the effect of operation pattern of flood control dam on water quality. Flood control dam temporarily impound floodwaters and then release them under control to the river below the dam preventing the river ecosystem from the extreme flood. The Hydrological Simulation Program Fortran (HSPF) and the Environmental Fluid Dynamics Code (EFDC) were adapted to predict the water quality before and after the dam construction in the proposed reservoir. The non-point pollutant delivery load from the river basin was estimated using the HSPF, and the EFDC was used to predict the water quality using the provided watershed boundary conditions from the HSPF. As a result of water quality simulation, it is predicted that the water quality will be improved due to the decrease of pollution source due to submergence after dam construction and temporary storage during rainfall. There would be no major water quality issues such as the eutrophication in the reservoir since the dam would impound the floodwater for a short time (2~3 days). In the environmental impact assessment stage of a planned dam, there may be some limitations to the exact simulation because the model can not be sufficiently calibrated. However, if the reliability of the model is improved through the acquisition of actual data in the future, it will be possible to examine the influence of the water environment according to various operating conditions in the environmental impact assessment of the new flood control dam.

• Imaging Science in Dentistry
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• v.34 no.3
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• pp.151-157
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• 2004

Purpose : To evaluate the quantitative accuracy of three-dimensional (3D) images by means of comparing distance measurements on the 3D images with direct measurements of dry human skull according to slice thickness and scanning modes. Materials and Mathods : An observer directly measured the distance of 21 line items between 12 orthodontic landmarks on the skull surface using a digital vernier caliper and each was repeated five times. The dry human skull was scanned with a Helical CT with various slice thickness (3, 5, 7 mm) and acquisition modes (Conventional and Helical). The same observer measured corresponding distance of the same items on reconstructed 3D images with the internal program of V-works 4.0/sup TM/(Cybermed Inc., Seoul, Korea). The quantitative accuracy of distance measurements were statistically evaluated with Wilcoxons' two-sample test. Results: 11 line items in Conventional 3 mm, 8 in Helical 3mm, 11 in Conventional 5mm, 10 in Helical 5mm, 5 in Conventional 7mm and 9 in Helical 7mm showed no statistically significant difference. Average difference between direct measurements and measurements on 3D CT images was within 2mm in 19 line items of Conventional 3mm, 20 of Helical 3mm, 15 of Conventional 5mm, 18 of Helical 5mm, II of Conventional 7mm and 16 of Helical 7mm. Conclusion: Considering image quality and patient's exposure time, scanning protocol of Helical 5mm is recommended for 3D image analysis of the skull in CT.

• Tuberculosis and Respiratory Diseases
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• v.81 no.2
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• pp.99-105
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• 2018

Acute exacerbation(s) of chronic obstructive pulmonary disease (AECOPD) tend to be critical and debilitating events leading to poorer outcomes in relation to chronic obstructive pulmonary disease (COPD) treatment modalities, and contribute to a higher and earlier mortality rate in COPD patients. Besides pro-active preventative measures intended to obviate acquisition of AECOPD, early recovery from severe AECOPD is an important issue in determining the long-term prognosis of patients diagnosed with COPD. Updated GOLD guidelines and recently published American Thoracic Society/European Respiratory Society clinical recommendations emphasize the importance of use of pharmacologic treatment including bronchodilators, systemic steroids and/or antibiotics. As a non-pharmacologic strategy to combat the effects of AECOPD, noninvasive ventilation (NIV) is recommended as the treatment of choice as this therapy is thought to be most effective in reducing intubation risk in patients diagnosed with AECOPD with acute respiratory failure. Recently, a few adjunctive modalities, including NIV with helmet and helium-oxygen mixture, have been tried in cases of AECOPD with respiratory failure. As yet, insufficient documentation exists to permit recommendation of this therapy without qualification. Although there are too few findings, as yet, to allow for regular andr routine application of those modalities in AECOPD, there is anecdotal evidence to indicate both mechanical and physiological benefits connected with this therapy. High-flow nasal cannula oxygen therapy is another supportive strategy which serves to improve the symptoms of hypoxic respiratory failure. The therapy also produced improvement in ventilatory variables, and it may be successfully applied in cases of hypercapnic respiratory failure. Extracorporeal carbon dioxide removal has been successfully attempted in cases of adult respiratory distress syndrome, with protective hypercapnic ventilatory strategy. Nowadays, it is reported that it was also effective in reducing intubation in AECOPD with hypercapnic respiratory failure. Despite the apparent need for more supporting evidence, efforts to improve efficacy of NIV have continued unabated. It is anticipated that these efforts will, over time, serve toprogressively decrease the risk of intubation and invasive mechanical ventilation in cases of AECOPD with acute respiratory failure.

• The Korea Journal of Herbology
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• v.26 no.4
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• pp.75-81
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• 2011

Objectives : Magnoliae officinalis Cortex (MOC) has been used in traditional medicine for digestive diseases in Korea, China and Japan. However, Machili thunbergii Cortex (MTC) also has been used as a substitute of MOC in Korea sometimes. Thus, this study was carried out to investigate and compare the effects of MOC and MTC on intestinal motility of isolated small intestinal segments from ICR mouse. Methods : Changes in motility were recorded via isometric transducers connected to a data acquisition system and amplitude, frequency and area under the curve (AUC) of intestinal spontaneous phasic contraction were compared. Results : The MOC extracts ($1{\sim}{\mu}g/mL$) dose-dependently decreased both amplitudes and frequencies of the spontaneous phasic contraction, but not AUC. However, high concentration of MOC (100 ${\mu}g$/mL) evoked tonic contraction. And it was not inhibited by tetrodotoxin, a sodium channel blocker, and nifedipine, a L-type $Ca^{2+}$ channel antagonist. These results suggested that MOC (100 ${\mu}g$/mL)-induced tonic contraction is not mediated by nerve or L-type $Ca^{2+}$ channel. On the other hand, the MTC extracts dose-dependently inhibited amplitude and AUC, but not the frequency. Conclusions : Although both MOC and MTC affected intestinal motility, MOC is more effective on intestinal motility than MTC. And MOC has been used as a traditional medicine for a long time but not MTC. Thus, we suggested that MTC should not be used in Korea as a substitute of MOC and MOC might be useful traditional medicine for gastrointestinal disease. The mechanism of MOC is still remained to elucidate.