• Korean Journal of Cognitive Science
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• v.23 no.4
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• pp.487-515
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• 2012

The purpose of this study was to investigate the effect of the individual differences in cognitive processes on paragraph comprehension. To do so, the lexical decision task and the pattern comparison task were used to measure the low-level cognitive processes. Digit span task was used to test the phonological loop capacity. The individual differences of the central executive processing capacity were measured by operational span task. Reading span task was used to test the working memory capacity related with the sentence processing. Reading times and accuracies of the logically valid inferences and logically void inferences were tested to measure the high-level cognitive processes. Reading times and accuracies for the target sentences with and without prior explicit causal sentence were measured to test individuals' paragraph comprehension abilities. The results showed that the speed of the low-level cognitive processes was related with the speed of the high-level cognitive processes. Also, the accuracy of the low-level cognitive processes was related with the accuracy of the high-level cognitive processes while there was no significant correlation between the speed and the accuracy in any measures of the cognitive processes. Working memory capacity was related with the accuracy of the cognitive processes while it was not significantly correlated with the speed of the cognitive processes. Most importantly, the speed of low-level cognitive processes significantly affected the speed of the paragraph comprehension while the working memory capacity and the high-level cognitive processes had influences on the accuracies of the paragraph comprehension. The speed of the paragraph comprehension had no influence on the accuracies of the paragraph comprehension.

• 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 Dental Rehabilitation and Applied Science
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• v.22 no.4
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• pp.317-328
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• 2006

Purpose: This study was performed to measure the accuracy of adjustable dental impression trays by a scanning laser three-dimensional digitizer. Materials and Methods: Metal stock tray and adjustable stock trays were used for 40 stone casts(10 casts each) duplicated a resin master model of mandible and maxilla. The type IV dental stone was poured in a allginate impressions and allowed to set for one hour. The casts were digitized using an optical digitizer. The distance between the reference points were measured and analyzed on the graphic image of 3-D graphic software (CATIA version 5.0). The statistical significance of the differences between the groups was determined by a two-way ANOVA. Results: There were no significant differences between the accuracies of the adjustable stock tray and the master model except anterior arch width of the upper arch and the diagonal arch length and arch length(one side) of the lower arch. Conclusion: The adjustable stock trays showed clinically acceptable accuracies of the study casts produced by them.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.1
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• pp.743-750
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• 2009

Since aerial photogrammetry by analog camera began in 1972, recently, high resolution digital camera is actively introduced to improve efficiency of aerial photogrammetry. This study investigated the 3D positioning accuracy of DMC(Digital Mapping Camera) among various high resolution aerial digital cameras to be developed for photogrammetry. For the research, we installed control points in test field around Incheon, and acquired analog and digital aerial photographs. By comparing 3D positioning accuracies of analog and digital photographs, there are few difference between two cameras, and the 3D positioning accuracies of two cameras was somewhat increased in case of aerotriangulation using additional control points based on GPS/IMU EO data.

• The Journal of the Acoustical Society of Korea
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• v.8 no.5
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• pp.23-32
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• 1989

The calibration of 1 inch standard condenser microphone is done by the reciprocity calibration method. There are two kinds of reciprocity calibration, free-field calibration and pressure calibration. The pressure sensitivities of the three 1 inch condenser microphones are determined by pressure calibration. The accuracy of the pressure sensitivity of the microphone depends on the accuracies of the voltage and dimension measurements as well as the various corrections for the coupler. If the individual accuracies for the measurements and corrections are achieved, it is estimated that the over-all accuracy is approximately 0.05dB at low and middle frequencies decreasing to about 0.ldB over 10kHz.

• The Korean Journal of Emergency Medical Services
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• v.24 no.1
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• pp.77-84
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• 2020

Purpose: This study was conducted to determine effective chest compression methods that could be used when performing cardiopulmonary resuscitation in rocking boats. Methods: Tests were conducted for four minutes using manual and mechanical chest compressions on two mannequins, placed in boats, and moving at a speed of 35km/hours on calm sea surfaces with wave heights of 0.5m and wind speeds of 2-3m/s (testing for two minutes, followed by rest, then a second round of testing for two minutes). To compare the quality of the chest compressions, data were analyzed using mannequins (Resusci Anne Q-CPR, Laerdal, Norway) and then statistically processed. Results: When chest compressions were administered in the moving rescue boat, an accuracy analysis showed that the pressure speed of the hand and mechanical techniques were normal, h owever, the pressure depth accuracies were 49.04% for manual techniques and 0% for mechanical techniques. The relaxation accuracies during compressions were 2.07% for manual techniques and 95.4% for mechanical techniques. Conclusion: When administering chest compressions in rocking rescue boats, mechanical rather than manual techniques should be preferentially considered.

• Water for future
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• v.29 no.6
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• pp.155-166
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• 1996

A finite element model for simulating gradually and rapidly varied unsteady flow in open channel is developed based on dynamic wave equation using Petrov-Galerkin method. A matrix stability analysis shows the selective damping of short wave lengths and excellent phase accuracies achived by Petrov-Galerkin method. Whereas the Preissmann scheme displays less selective damping and poor phase accuracies, and Bubnov-Galerkin method shows nondissipative characteristics whicn causes a divergence problem in short wave length. The analysis also shows that the Petrov-Galerkin method displays the desirable combination of selective damping of high frequency progressive waves over a wide range of Courant number and good phase accuracy at low Courant number. Therefore, the Petrov-Galerkin can be effectively applied to gradually and rapidly varied unsteady flow.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.7
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• pp.644-650
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• 2005

The expected positioning accuracies of civil users utilizing modernized GPS and Galileo are derived using the error analysis in this paper. Since, in general, the performance of DLL, PLL and FLL is proportional to chip lengths and wavelengths, the positioning accuracies from various measurements of modernized GPS and Galileo are derived as function of chip length and wavelength. These results are compared with that from GPS Ll measurement. In absolute positioning, compared to GPS C/A code only case, more than 17 times performance improvement is expected when all civil code signals of modernized GPS and Galileo (L1, L2, L5, E1, E5A and E5B) are used. In relative positioning, compared to GPS L1 carrier phase only case, more than 2 times performance improvement is expected when all civil signals of modernized GPS and Calileo are used. Furthermore, the relationship between GDOP and RGDOP in single frequency case is expanded to general case where multiple frequencies and both code and carrier phase measurements are used.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.219-228
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• 1993

The development of the Global Positioning System was one of the most significant technical advancements in the surveying fields during the 1980's. In recent years, the use of GPS techniques are increased because of the improvements of receiver design and the data analysis, and the greater accuracy. In this paper, the static positioning with special linear combinations of data is reviewed and some experiences of dual-frequency P-code/phase receivers are discussed. The test results of Wild GPS System-200 show that the highest accuracies of 1ppm are obtainable on baselines of 7km/37km and the positional accuracies of 10m, which is applicable to determination of initial coordinates, are also possible on point-positioning of P-code measurements.

• Journal of Soil and Groundwater Environment
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• v.21 no.3
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• pp.21-34
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• 2016

In the present study, we applied various machine learning techniques comparatively for prediction of subsurface structures based on multiple secondary information (i.e., well-logging data). The machine learning techniques employed in this study are Naive Bayes classification (NB), artificial neural network (ANN), support vector machine (SVM) and logistic regression classification (LR). As an alternative model, conventional hidden Markov model (HMM) and modified hidden Markov model (mHMM) are used where additional information of transition probability between primary properties is incorporated in the predictions. In the comparisons, 16 boreholes consisted with four different materials are synthesized, which show directional non-stationarity in upward and downward directions. Futhermore, two types of the secondary information that is statistically related to each material are generated. From the comparative analysis with various case studies, the accuracies of the techniques become degenerated with inclusion of additive errors and small amount of the training data. For HMM predictions, the conventional HMM shows the similar accuracies with the models that does not relies on transition probability. However, the mHMM consistently shows the highest prediction accuracy among the test cases, which can be attributed to the consideration of geological nature in the training of the model.