• Korean Journal of Agricultural and Forest Meteorology
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• v.2 no.4
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• pp.175-182
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• 2000

Spatial interpolation of daily temperature forecasts and observations issued by public weather services is frequently required to make them applicable to agricultural activities and modeling tasks. In contrast to the long term averages like monthly normals, terrain effects are not considered in most spatial interpolations for short term temperatures. This may cause erroneous results in mountainous regions where the observation network hardly covers full features of the complicated terrain. We developed a spatial interpolation model for daily minimum temperature which combines inverse distance squared weighting and elevation difference correction. This model uses a time dependent function for 'mountain slope lapse rate', which can be derived from regression analyses of the station observations with respect to the geographical and topographical features of the surroundings including the station elevation. We applied this model to interpolation of daily minimum temperature over the mountainous Korean Peninsula using 63 standard weather station data. For the first step, a primitive temperature surface was interpolated by inverse distance squared weighting of the 63 point data. Next, a virtual elevation surface was reconstructed by spatially interpolating the 63 station elevation data and subtracted from the elevation surface of a digital elevation model with 1 km grid spacing to obtain the elevation difference at each grid cell. Final estimates of daily minimum temperature at all the grid cells were obtained by applying the calculated daily lapse rate to the elevation difference and adjusting the inverse distance weighted estimates. Independent, measured data sets from 267 automated weather station locations were used to calculate the estimation errors on 12 dates, randomly selected one for each month in 1999. Analysis of 3 terms of estimation errors (mean error, mean absolute error, and root mean squared error) indicates a substantial improvement over the inverse distance squared weighting.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.173-177
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• 2007

현재 농업용수 이용량은 158억$m^3/yr$로 우리나라 전체 수자원이용량의 48%에 해당되며 하천유지수량을 제외하였을 경우 61%에 해당된다. 농업용수의 이용은 노후화된 농업수리시설과 관리기술 부족 등의 원인으로 이용효율이 낮은 것으로 추정되고 있다. 그러나 이러한 현황을 뒷받침해 줄 측정 및 조사자료가 부족한 실정이다. 농업용수의 물관리 연구는 장기간의 신뢰성 있는 수문자료의 획득이 절대적으로 필요하고 실제 현장에서의 물관리 상황을 조사파악하는 것이 중요한다. 이러한 자료의 축척은 체계적이고 일관되게 수행되어야 한다. 이를 위하여 한국농촌공사에서는 2000년에 경기도 용인에 위치한 이동저수지 유역을 종합시험지구로 선정하여 운영하게 되었다. 이동시험지구는 경기도 용인시, 평택시, 안성시, 사이에 위치한 전형적인 농촌지역이다. 저수지와 양수장 시설이 복합적으로 운영되어 농업용수를 공급하는 지구로 농업용수의 물관리 연구 수행을 위해 적합한 지역이다. 이동시험지구에 강우계, 저수지 수위계, 하천 수위계, 수로 수위계를 설치하여 운영하고 있으며 정기적으로 유지 관리 및 자료수집을 함으로써 신뢰성 있는 농촌지역 수문자료를 축척하고 있다. 이동시험지구의 운영은 농업용수 물관리와 관련된 체계적이고 신뢰성 있는 장기간의 수문자료를 축척하고 축척된 현장 자료의 분석을 통해 물관리 기초자료를 계량화 하는데 그 목적이 있다. 본 연구의 목적은 실제 농업용 저수지의 용수공급 운영에 따라 하천에서의 유출특성에 대한 조사를 통하여, 농업용저수지가 하천에 미치는 영향을 파악하고자 한다. 시험지구 덕성교 하천수위관측지점의 하천유출율은 65 %, 재인교 하천수위관측지점의 경우 하천유출율은 60 %를 나타내었다. 이동유역의 경우 상류에 저수지가 있으며 저수지의 시기별 저수상태와 강우량에 따라 유출에 영향을 받고 있다. 1월에 상류 저수지의 저수상태가 만수를 유지하고 있었으며 예년에 비하여 많은 강우가 발생하여 저수위 조절 차원에서 인위적으로 방류한 양이 많았기 때문으로 추정할 수 있다. 두 지점의 1월 유출이 100 % 이상인 것은 동절기 하천 결빙으로 인한 유량파악이 힘든 것으로 나타났다. 1월의 하천수위는 계측기에 기록된 수위값으로 유량을 산정한 것이다. 3월, 10월, 12월의 유출이 많은 것은 전월말 발생한 강우의 영향으로 크게 나타났다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.5
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• pp.445-458
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• 2012

The objective of GPS control surveying is ultimately to determine coordinate sets of control points within targeted accuracy through a series of observations and network adjustments. To this end, it is of equivalent importance for the accuracy of these coordinates to be realistically represented by using an appropriate method. The accuracy representation can be quantitively made by the variance-covariance matrices of the estimates, of which features are sensitive to the mathematical models used in the adjustment. This paper deals with impact of functional and stochastic modeling techniques into the accuracy representation of the GPS control surveying with a view of gaining background for its standardization. In order to achieve this goal, mathematical theory and procedure of the single-baseline based multi-session adjustment has been rigorously reviewed together with numerical analysis through processing real world data. Based on this study, it was possible to draw a conclusion that weighted-constrained adjustment with the empirical stochastic model was among the best scheme to more realistically describe both of the absolute and relative accuracies of the GPS surveying results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2123-2130
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• 2015

For such automatic monitoring robot or a robot cleaner that is utilized indoors, if it deviates from someone by replacement or, or of a mobile robot such as collisions with unexpected object direction or planned path, based on the planned path There is a need to come back to, it is necessary to tough self-position estimation ability of mobile robot in this, which is also associated with resolution of the kidnap problem of conventional mobile robot. In this study, the case of a mobile robot, operates indoors, you want to take advantage of the low cost of the robot. Therefore, in this paper, by using the acquisition device to an external image information such as the CCTV which is installed in a room, it acquires the environment image and take advantage of marker recognition of the mobile robot at the same time and converted it absolutely spatial coordinates it is, we are trying to solve the self-position estimation of the mobile robot in the room and kidnap problem and actual implementation methods potential field to try utilizing robotic systems. Thus, by implementing the method proposed in this study to the actual robot system, and is promoting the relevant experiment was to verify the results.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1125-1139
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• 2022

In an unmanned aerial vehicles (UAVs) system, a physical offset can be existed between the global positioning system/inertial measurement unit (GPS/IMU) sensor and the observation sensor such as a hyperspectral sensor, and a lidar sensor. As a result of the physical offset, a misalignment between each image can be occurred along with a flight direction. In particular, in a case of multi-sensor system, an observation sensor has to be replaced regularly to equip another observation sensor, and then, a high cost should be paid to acquire a calibration parameter. In this study, we establish a precise sensor model equation to apply for a multiple sensor in common and propose an independent physical offset estimation method. The proposed method consists of 3 steps. Firstly, we define an appropriate rotation matrix for our system, and an initial sensor model equation for direct-georeferencing. Next, an observation equation for the physical offset estimation is established by extracting a corresponding point between a ground control point and the observed data from a sensor. Finally, the physical offset is estimated based on the observed data, and the precise sensor model equation is established by applying the estimated parameters to the initial sensor model equation. 4 region's datasets(Jeon-ju, Incheon, Alaska, Norway) with a different latitude, longitude were compared to analyze the effects of the calibration parameter. We confirmed that a misalignment between images were adjusted after applying for the physical offset in the sensor model equation. An absolute position accuracy was analyzed in the Incheon dataset, compared to a ground control point. For the hyperspectral image, root mean square error (RMSE) for X, Y direction was calculated for 0.12 m, and for the point cloud, RMSE was calculated for 0.03 m. Furthermore, a relative position accuracy for a specific point between the adjusted point cloud and the hyperspectral images were also analyzed for 0.07 m, so we confirmed that a precise data mapping is available for an observation without a ground control point through the proposed estimation method, and we also confirmed a possibility of multi-sensor fusion. From this study, we expect that a flexible multi-sensor platform system can be operated through the independent parameter estimation method with an economic cost saving.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.12
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• pp.1492-1499
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• 2019

This paper propose how to track the position of the observer to control the viewing zone using an adaptive parallax barrier. The pose is estimated using a Constrained Local Model based on the shape model and Landmark for robust eye-distance measurement in the face pose. Camera's correlation converts distance and horizontal location to centimeter. The pixel pitch of the adaptive parallax barrier is adjusted according to the position of the observer's eyes, and the barrier is moved to adjust the viewing area. This paper propose a method for tracking the observer in the range of 60cm to 490cm, and measure the error, measurable range, and fps according to the resolution of the camera image. As a result, the observer can be measured within the absolute error range of 3.1642cm on average, and it was able to measure about 278cm at 320×240, about 488cm at 640×480, and about 493cm at 1280×960 depending on the resolution of the image.

• Journal of Advanced Navigation Technology
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• v.26 no.6
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• pp.427-433
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• 2022

Obstacle detection, collision recognition, and avoidance technologies are required the collision avoidance technology for UAVs. In this paper, considering collinear multiple static obstacle, we propose an obstacle detection algorithm using LiDAR and a collision recognition and avoidance algorithm based on CPA. Preprocessing is performed to remove the ground from the LiDAR measurement data before obstacle detection. And we detect and classify obstacles in the preprocessed data using the K-means clustering algorithm. Also, we estimate the absolute positions of detected obstacles using relative navigation and correct the estimated positions using a low-pass filter. For collision avoidance with the detected multiple static obstacle, we use a collision recognition and avoidance algorithm based on CPA. Information of obstacles to be avoided is updated using distance between each obstacle, and collision recognition and avoidance are performed through the updated obstacles information. Finally, through obstacle location estimation, collision recognition, and collision avoidance result analysis in the Gazebo simulation environment, we verified that collision avoidance is performed successfully.

• Journal of the Korean Society for Railway
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• v.19 no.3
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• pp.304-313
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• 2016

It is necessary to receive telegrams transmitted by transponder tags installed along the track in order to detect the exact position of a high-speed train. In a high-speed railway environment, telegrams can be corrupted by the electromagnetic interference that comes from onboard electric train power equipment or wayside devices. In this study, we verified the railway environment compatibility of a high-speed transponder system developed as a train position detection system. We installed transponder tags on the Honam high-speed line and measured the number of error-free telegrams received from the transponder tag while the HEMU-430X was running at 268km/h~334km/h. Based on the measurement, we estimated the length of the contact zone formed between the transponder reader and tag. Field test results allow us to estimate how many error-free telegrams can be received when HEMU-430X is at speeds up to 400km/h.

• Progress in Medical Physics
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• v.26 no.3
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• pp.143-152
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• 2015

In this study, we aim to design the architecture of the kV imaging system for tumor tracking in the dual-head gantry system and analyze its accuracy by simulations. We established mathematical formulas and algorithms to track the tumor position with the two-pair kV imaging systems when they are in the non-orthogonal positions. The algorithms have been designed in the homogeneous coordinate framework and the position of the source and the detector coordinates are used to estimate the tumor position. 4D XCAT (4D extended cardiac-torso) software was used in the simulation to identify the influence of the angle between the two-pair kV imaging systems and the resolution of the detectors to the accuracy in the position estimation. A metal marker fiducial has been inserted in a numerical human phantom of XCAT and the kV projections were acquired at various angles and resolutions using CT projection software of the XCAT. As a result, a positional accuracy of less than about 1mm was achieved when the resolution of the detector is higher than 1.5 mm/pixel and the angle between the kV imaging systems is approximately between $90^{\circ}$ and $50^{\circ}$. When the resolution is lower than 1.5 mm/pixel, the positional errors were higher than 1mm and the error fluctuation by the angles was greater. The resolution of the detector was critical in the positional accuracy for the tumor tracking and determines the range for the acceptable angle range between the kV imaging systems. Also, we found that the positional accuracy analysis method using XCAT developed in this study is highly useful and will be a invaluable tool for further refined design of the kV imaging systems for tumor tracking systems.

• The Korean Journal of Malacology
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• v.7 no.1
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• pp.30-48
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• 1991

한국해역 종합 해양자원도 작성연구(남해)의 일환으로 저서생물 분포 연구를 위한 조사가 1990년 7월과 8월에 남해에 위치한 83개 조사정점에서 수행되었다. 각 정점에서 van Veen그랩으로 3회씩 채집된 저서 생물 표본 가운데 연체동물만을 선별 그들의 분포 양상을 파악하고자 종 동정과 함께 군집구조 분석을 하였다. 조사에서 채집된 연체동물은 모두 679개로 다섯개 강에 102종으로 동정되었으며, 이매패류가 출현종수(84.3%)에서나 출현개체수(92.3%)에 있어서 절대우점하였다. 전체 연체동물군집에서 우점하는 일곱 종(이매패류 여섯 종, 무판류 한 종)이 전체 출현개체수의 61.0%를 차지하였다. 남해의 연체동물은 종은 다양한 반면에 서식밀도나 생물량은 매우 빈약하였다. 출현종의 서식 유무에 따른 유사도로써 집괴분석한 결과 다섯개의 조사정점군으로 나누어지고, 이 들은 특징적인 분포 특성을 갖는 두 정점군과 혼합된 특성을 나타내는 세정점군으로 대별되었다. 전자의 두 정점군은 Raetellops Pulchella와 Periploma otohimeae로 대표되는 황해의 저층냉수의 영향을 받는 세립퇴적물 군집과 뚜렷한 대표종은 없지만 대마난류의 영향을 받는 이질성의 조립퇴넉물 군집으로 정의할 수 있었다. 대마난류의 영향을 받는 정점군의 군집은 황해저층냉수의 정점군에 비해 종 다양도는 높지만, 서식생물량은 현저히 적었다. 아울러 연체동물의 분포와 남해의 퇴적환경이나 수괴의 조성과 변화를 고려하여 남해에 서식하는 저서생물 군집에 있어서 네 개의 분포구역이 있을 것으로 추정하여 그 범위와 경계를 제안한다.