• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.2
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• pp.10-23
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• 2009

The fundamental matrix and key frame selection are one of the most important techniques to recover full 3D reconstruction of objects from turntable sequences. This paper proposes a new algorithm that estimates a robust fundamental matrix for camera calibration from uncalibrated images taken under turn-table motion. Single axis turntable motion can be described in terms of its fixed entities. This provides new algorithms for computing the fundamental matrix. From the projective properties of the conics and fundamental matrix the Euclidean 3D coordinates of a point are obtained from geometric locus of the image points trajectories. Experimental results on real and virtual image sequences demonstrate good object reconstructions.

• Journal of Korean Society on Water Environment
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• v.37 no.2
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• pp.103-113
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• 2021

In this study, an Excel-based model (ROADMOD) was developed to estimate pollutant loading from the road and evaluate BMPs. ROADMOD employs the Chezy-Manning equation and empirical expression for estimating surface runoff, and power function for pollutant buildup, and exponential function for pollutant washoff in SWMM. The results of model calibration for buildup and washoff using observed data revealed a good match between the simulation results and the observed data. The long-term surface runoff and sediment simulated by ROADMOD demonstrated a good match with those by SWMM with 2 ~ 14% of relative error. The shorter sweeping interval (within 8 days) remarkably decreased sediment loads from the road. It was found that the effect of reducing sediment loads from the road was greatly affected not only by the sweeping interval but also by sweeping on the day before a rainfall event. The 48% of removal efficiency of sediment loads from the road was achieved with 26 times of road sweeping per year when sweeping was performed on the day before the rainfall event. A 4-day sweeping interval showed similar removal efficiency (48%) with 96 times of sweeping per year. It is considered that the road sweeping on the day before a rainfall event could maximize the effect of reducing the non-point source pollution from the road with minimization of the number of road sweeping. So, the road sweeping on the day before a rainfall event can be considered as one of the useful and best management practices (BMPs) on road.

• Korean Journal of Remote Sensing
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• v.35 no.5_1
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• pp.665-679
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• 2019

Mesoscale soil moisture measurement from the promising Cosmic-Ray Neutron Probe (CRNP) is expected to bridge the gap between large scale microwave remote sensing and point-based in-situ soil moisture observations. Traditional calibration based on $N_0$ method is used to convert neutron intensity measured at the CRNP to field scale soil moisture. However, the static calibration parameter $N_0$ used in traditional technique is insufficient to quantify long term soil moisture variation and easily influenced by different time-variant factors, contributing to the high uncertainties in CRNP soil moisture product. Consequently, in this study, we proposed a modified traditional calibration method, so-called Dynamic-$N_0$ method, which take into account the temporal variation of $N_0$ to improve the CRNP based soil moisture estimation. In particular, a nonlinear regression method has been developed to directly estimate the time series of $N_0$ data from the corrected neutron intensity. The $N_0$ time series were then reapplied to generate the soil moisture. We evaluated the performance of Dynamic-$N_0$ method for soil moisture estimation compared with the traditional one by using a weighted in-situ soil moisture product. The results indicated that Dynamic-$N_0$ method outperformed the traditional calibration technique, where correlation coefficient increased from 0.70 to 0.72 and RMSE and bias reduced from 0.036 to 0.026 and -0.006 to $-0.001m^3m^{-3}$. Superior performance of the Dynamic-$N_0$ calibration method revealed that the temporal variability of $N_0$ was caused by hydrogen pools surrounding the CRNP. Although several uncertainty sources contributed to the variation of $N_0$ were not fully identified, this proposed calibration method gave a new insight to improve field scale soil moisture estimation from the CRNP.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.2
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• pp.102-114
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• 2013

The basin of Lake Shihwa is one of highly industrialized region of Korea and a current environmental issue of study area is the operation of tidal power plant (TPP) to improve water quality. The application of water quality index (WQI) which integrates five physiochemical parameters (transparency, DO, DIN, DIP and chlorophyll-a) of water quality in Lake Shihwa and outer sea during 2011~2012 were performed not only to evaluate the spatial and temporal distribution of the water quality but also to assess the effect of water quality improvement by the operation of tidal power plant. The higher WQI values were observed in monitored sites near the industrial complexes in Lake Shihwa and the outfall of wastewater treatment plants (WWTPs) in outer sea. This indicates that the quality of seawater is influenced by diffuse non-point sources from industrial, municipal and agricultural areas in Lake Shihwa and by point sources from the effluence of municipal and industrial wastewater throughout WWTPs in outer sea. Mean WQI value decreased from 53.0 in 2011 to 42.8 in 2012 of Lake Shihwa. Water quality has improved significantly after TPP operation because enhancement of seawater exchange between Lake Shihwa and outer sea leads to improve a hypoxic condition which is primarily a problem in Lake Shihwa. Mean WQI of outer sea showed similar values between 2011 and 2012. However, the results of hierarchical cluster analysis and the deterioration of water quality in summer season indicate that the operation of tidal power plant was not improved the water quality in the upper most area of Lake Shihwa. To successfully improve overall water quality of Lake Shihwa, it is urgently necessary to manage and reduce of non-point pollution sources of the basin of Lake Shihwa.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.1
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• pp.29-34
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• 2017

A CMOS-based temperature sensor is proposed for low-voltage and low-power on-chip thermal monitoring applications. The proposed temperature sensor converts a proportional to absolute temperature (PTAT) current to a PTAT frequency using an integrator and hysteresis comparator. In addition, it operates in the subthreshold region, allowing reduced power consumption. The proposed temperature sensor was fabricated in a standard 90 nm CMOS technology. Measurement results of the proposed temperature sensor show a temperature error of between -0.81 and $+0.94^{\circ}C$ in the temperature range of 0 to $70^{\circ}C$ after one-point calibration at $30^{\circ}C$, with a temperature coefficient of $218Hz/^{\circ}C$. Moreover, the measured energy of the proposed temperature sensor is 36 pJ per conversion, the lowest compared to prior works.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.290-293
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• 2009

In this paper, we propose a method to estimate pointing region in real-world from images of cameras. In general, arm-pointing gesture encodes a direction which extends from user's fingertip to target point. In the proposed work, we assume that the pointing ray can be approximated to a straight line which passes through user's face and fingertip. Therefore, the proposed method extracts two end points for the estimation of pointing direction; one from the user's face and another from the user's fingertip region. Then, the pointing direction and its target region are estimated based on the 2D-3D projective mapping between camera images and real-world scene. In order to demonstrate an application of the proposed method, we constructed an ICGS (interactive cinema guiding system) which employs two CCD cameras and a monitor. The accuracy and robustness of the proposed method are also verified on the experimental results of several real video sequences.

• Journal of Korean Society on Water Environment
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• v.35 no.2
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• pp.131-144
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• 2019

Climate Change affects the hydrological cycle in agricultural watersheds through rising air temperature and changing rainfall patterns. Agricultural watersheds in Korea are characterized by extensive paddy fields and intensive water use, a resource that is under stress from the changing climate. This study analyzed the effects of climate change on river flows for Geum Cheon and Eun-San Choen watershed using STREAM, a semi-distributed watershed model. In order to evaluate the performance and improve the reliability of the model, calibration and validation of the model was done for one flow observation point and three reservoir water storage ratio points. Climate change scenarios were based on RCP data provided by the Korea Meteorological Administration (KMA) and bias corrections were done using the Quantile Mapping method to minimize the uncertainties in the results produced by the climate model to the local scale. Because of water mass-balance, evapotranspiration tended to increase steadily with an increase in air temperature, while the increase in RCP 8.5 scenario resulted in higher RCP 4.5 scenario. The increase in evapotranspiration led to a decrease in the river flow, particularly the decrease in the surface runoff. In the paddy agricultural watershed, irrigation water demand is expected to increase despite an increase in rainfall owing to the high evapotranspiration rates occasioned by climate change.

• Smart Structures and Systems
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• v.25 no.2
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• pp.135-153
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• 2020

There has been a sustained interest towards the non-contact structural displacement measurement by means of videogrammetric technique. On the way forward, one of the major concerns is the spurious image drift induced by temperature variation. This study therefore carries out an investigation into the temperature effect of videogrammetric technique, focusing on the exploration of the mechanism behind the temperature effect and the elimination of the temperature-caused measurement error. 2D videogrammetric measurement tests under monotonic or cyclic temperature variation are first performed. Features of measurement error and the casual relationship between temperature variation and measurement error are then studied. The variation of the temperature of digital camera is identified as the main cause of measurement error. An excellent linear relationship between them is revealed. After that, camera parameters are extracted from the mapping between world coordinates and pixels coordinates of the calibration targets. The coordinates of principle point and focal lengths show variations well correlated with temperature variation. The measurement error is thought to be an outcome mainly attributed to the variation of the coordinates of principle point. An approach for eliminating temperature-caused measurement error is finally proposed. Correlation models between camera parameters and temperature are formulated. Thereby, camera parameters under different temperature conditions can be predicted and the camera projective matrix can be updated accordingly. By reconstructing the world coordinates with the updated camera projective matrix, the temperature-caused measurement error is eliminated. A satisfactory performance has been achieved by the proposed approach in eliminating the temperature-caused measurement error.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.6
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• pp.625-635
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• 2014

Multiple strips are required for large area mapping using ALS (Airborne Laser Scanner) system. LiDAR (Light Detection And Ranging) data collected from the ALS system has discrepancies between strips due to systematic errors of on-board laser scanner and GPS/INS, inaccurate processing of the system calibration as well as boresight misalignments. Such discrepancies deteriorate the overall geometric quality of the end products such as DEM (Digital Elevation Model), building models, and digital maps. Therefore, strip adjustment for minimizing discrepancies between overlapping strips is one of the most essential tasks to create seamless point cloud data. This study implemented area-based matching (ABM) to determine conjugate features for computing 3D transformation parameters. ABM is a well-known method and easily implemented for this purpose. It is obvious that the exact same LiDAR points do not exist in the overlapping strips. Therefore, the term "conjugate point" means that the location of occurring maximum similarity within the overlapping strips. Coordinates of the conjugate locations were determined with sub-pixel accuracy. The major drawbacks of the ABM are sensitive to scale change and rotation. However, there is almost no scale change and the rotation angles are quite small between adjacent strips to apply AMB. Experimental results from this study using both simulated and real datasets demonstrate validity of the proposed scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2C
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• pp.229-237
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• 2004

In this paper. we propose a new autocalibration algorithm. 3D-based image synthesis is roughly divided into two methods. One is using autocalibration method, and the other is using real 3D data like pattern information. The former is more progressive method. because there is no constraint or information about the scenes. Therefore autocalibration method has very difficult progress dealing with complicate non-lineal equations. Nowadays, constraints of camera intrinsic parameters are used in many researches. Therefore we solve the linear equations instead of complicate non-lineal equations. For example, to fix principal point of camera is a representative method.