• Korean Journal of Agricultural and Forest Meteorology
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• v.6 no.3
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• pp.177-182
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• 2004

A chill unit has been used to estimate chilling requirement for dormancy release and risk of freezing damage. A system that calculates chill units was developed to obtain site-specific estimates of dormancy release date for grapes and evaluated in Baekgu myun near Kimje City, Chunbuk, Korea from September 2002 to March 2003. The system utilized daily minimum and maximum temperature maps generated from spatial interpolation with temperature correction for topography. Hourly temperature was temporally interpolated from the daily data using a sine-exponential equation (Patron and Logan, 1981). Hourly chill units were determined from sigmoid, reverse sigmoid, and negatively increasing sigmoid functions based on temperature ranges and summed for 24 h. Cumulative daily chill units obtained from measurements did not increase until 20 October 2002, which was used as a start date for accumulation to estimate the dormancy release date. As a result, a map of dormancy release date in the study area was generated, assuming 800 chill units as a threshold for the chilling requirement. The chill unit accumulation system, implemented using Microsoft Visual Basic and C++ (Microsoft, Redmond, WA, USA), runs in the Windows environment with ArcView (ESRl Inc., Redlands, CA, USA).

• Journal of Korea Spatial Information System Society
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• v.3 no.2 s.6
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• pp.5-19
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• 2001

We are able to construct and utilize DEM(Digital Elevation Model) throughout the NGIS(National Geographic Information System) project. It is important that interpolation methods and appreciate size of grid for the construction of accurate DEM(Digital Elevation Model). There were several references related to the DEM(Digital Elevation Model) construction method, however they couldn't consider various topographical characteristics in the korea. In this study, we recommended that suitable interpolation method for each topographic element. After dividing Poonggi area into mountain, hill, urban, agricultural land, we constructed DEM(Digital Elevation Model) with various interpolation methods and grid size using 1:5,000 digital map. Then evaluated accuracy using elevation data which extracted from air-photo. The interpolation methods were analyzed and compared for various topographical conditions. As a result, Kriging method was superior to TIN method for all the topographical conditions. Another experiment was performed to examine optimal grid space for DEM with each topographical condition. 10m grid space was most suitable for mountain area and hilly districts, while 30m grid space was most suitable for urban area and farm land.

• Spatial Information Research
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• v.23 no.5
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• pp.31-40
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• 2015

The purpose of this paper is to propose a data transformation method for visualizing the statistical information based on the grid system which has regular shape and size. Grid is better solution than administrator boundary or census block to check the distribution of the statistical information and be able to use as a spatial unit on the map flexibly. On the other hand, we need the additional process to convert the various statistical information to grid if we use the current method which is areal interpolation. Therefore, this paper proposes the 3 steps to convert the various statistical information to grid. 1)Geocoding the statistical information, 2)Converting the spatial information through the defining the spatial relationship, 3)Attribute transformation considering the data scale measurement. This method applies to the population density of Seoul to convert to the grid. Especially, spatial autocorrelation is performed to check the consistency of grid display if the reference data is different for same statistic information. As a result, both distribution of grid are similar to each other when the population density data which is represented by census block and building is converted to grid. Through the result of implementation, it is demonstrated to be able to perform the consistent data conversion based on the proposed method.

• Advances in robotics research
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• v.1 no.2
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• pp.127-140
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• 2014

This work presents an IR-based system for parking assistance and obstacle detection in the automotive field that employs the Microsoft Kinect camera for fast 3D point cloud reconstruction. In contrast to previous research that attempts to explicitly identify obstacles, the proposed system aims to detect "reachable regions" of the environment, i.e., those regions where the vehicle can drive to from its current position. A user-friendly 2D traversability grid of cells is generated and used as a visual aid for parking assistance. Given a raw 3D point cloud, first each point is mapped into individual cells, then, the elevation information is used within a graph-based algorithm to label a given cell as traversable or non-traversable. Following this rationale, positive and negative obstacles, as well as unknown regions can be implicitly detected. Additionally, no flat-world assumption is required. Experimental results, obtained from the system in typical parking scenarios, are presented showing its effectiveness for scene interpretation and detection of several types of obstacle.

• The Journal of Korea Robotics Society
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• v.17 no.4
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• pp.397-406
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• 2022

This paper presents an autonomous mobile robot (AMR) system and operation algorithms for logistic and factory facilities without magnet-lines installation. Unlike widely used AMR systems, we propose an EKF-based loosely coupled fusion of LiDAR measurements and visual markers. Our method first constructs occupancy grid and visual marker map in the mapping process and utilizes prebuilt maps for precise localization. Also, we developed a waypoint-based navigation pipeline for robust autonomous operation in unconstrained environments. The proposed system estimates the robot pose using by updating the state with the fusion of visual marker and LiDAR measurements. Finally, we tested the proposed method in indoor environments and existing factory facilities for evaluation. In experimental results, this paper represents the performance of our system compared to the well-known LiDAR-based localization and navigation system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.547-552
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• 2003

In mold machining, there are many concave machining regions where chatter and tool deflection occur since MRR (material removal rate) increases as curvature increases even though cutting speed and depth of cut are constant. Boolean operation between stock and tool model is widely used to compute MRR in NC milling simulation. In finish cutting, the side step is reduced to about 0.3mm and tool path length is sometimes over 300m. so Boolean operation takes long computation time and includes much error if the resolution of stock and tool model is larger than the side step. In this paper, curvature of CL(cutter location) surface and side step of tool path is used to compute the feedrate for constant MRR machining. The data structure of CL surface is Z-map generated from NC tool path. The algorithm to get local curvature from discrete data was developed and applied to compute local curvature of CL surface. The side step of tool path was computed by point density map which includes cutter location point density at each grid element. The feedrate computed from curvature and side step is inserted to new tool path to regulate MRR. The resultants wire applied to feedrate optimization system which generates new tool path with feedrate from NC codes for finish cutting. The system was applied to speaker mold machining. The finishing time was reduced to 12.6%. tool wear was reduced from 2mm to 1.1mm and chatter marks and over cut on corner were removed.

• Smart Media Journal
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• v.9 no.2
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• pp.51-62
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• 2020

Starting with the "Smart Grid National Road Map" in 2010, the Smart Grid 2030 was introduced through the basic plan and implementation plan of the intelligent power grid with the goal of building the world's first national smart grid. In this paper, we intend to build a power domain ontology based on the power business platform based on the upper and lower conceptual models of the "Smart Grid Interoperability Standard Framework and Roadmap", the standard of implementation plan. Ontology is suitable for expressing and utilizing the smart grid conceptual model because it considers hierarchical structure as knowledge defines the properties of entities and relationships between entities, but there is no research related to them. Therefore, in this paper, the upper ontology was defined as a major category for smart grid-related fields, and the lower ontology was defined as detailed systems and functions for the upper ontology to construct the ontology. In addition, scenarios in various situations that could occur in the power system were constructed and significant inference results were derived through inference engines and queries.

• Journal of the Korea Society of Computer and Information
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• v.17 no.6
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• pp.173-182
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• 2012

A recent advance in smart phones is increasing utilization of location information. Existing positioning system was using GPS location for positioning. However, the GPS cannot be used indoors, if GPS location has an incorrectly problem. In order to solve indoor positioning problems of indoor location-based positioning techniques have been investigated. There are a variety of techniques based on indoor positioning techniques like as RFID, UWB, WLAN, etc. But WLAN location positioning techniques take advantage the bond in real life. WLAN indoor positioning techniques have a two kind of method that is centroid and fingerprint method. Among them, the fingerprint technique is commonly used because of the high accuracy. In order to use fingerprinting techniques make a WLAN signal map building that is need to lot of resource. In this paper, we try to solve this problem in an Indoor environment for WLAN-based fingerprint of a virtual building technique, which is proposed. Proposed technique is classified Cell environment in existed Indoor environment, all of fingerprint points are shown virtual grid map in each Cell. Its method can make fingerprint grid map very quickly using estimate virtual signal value. Also built signal value can take different value depending of the real estimate value. To solve this problem using a calibration technique for the Splite-tree is proposed. Through calibration technique that improves the accuracy for short period of time. It also is improved overall accuracy using predicted value of around position in cell.

• Journal of Korea Water Resources Association
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• v.48 no.11
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• pp.925-936
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• 2015

The purpose of this study is to explore the effectiveness of dual-polarization radar rainfall by comapring with the flood inundation record map through KIMSTORM(Grid-based KIneMatic wave STOrm Runoff Model). For Namgang dam ($2,293km^2$) watershed, the Bisl dual-polarization radar data for 3 typhoons (Khanun, Bolaven, Sanba) and 1 heavy rain event in 2012 were prepared. For both 28 ground rainfall data and radar rainfall data, the model was calibrated using observed discharge data at 5 stations with $R^2$, Nash and Sutcliffe Model Efficiency (ME) and Volume Conservation Index (VCI). The calibration results of $R^2$, ME and VCI were 0.85, 0.78 and 1.09 for ground rainfall and 0.85, 0.79, and 1.04 for radar rainfall respectively. The flood inundation record areas (SY and MD/SG district) by typhoon Sanba were compared with the distributed modeling results. The spatial distribution by radar rainfall produced more surface runoff from the watershed and simulated higher stream discharge than the ground rainfall condition in both SY and MD/SG district. In case of MD/SG district, the stream water level by radar rainfall near the flood inundation area showed 0.72 m higher than the water level by ground rainfall.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.64.2-64
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• 2001

In this paper, fabricated is a motion capture and attitude detection system for Head Mounted Display HMD composed of three low-price and low-grade micro gyroscopes and a micro-controller, To calculate attitude of a body, modified INS algorithm is used. Because the micro gyroscope has much bias drift error, scale factor error, and run-to-run bias error, the motion of a body can not be measured exactly if the general INS algorithm and micro gyroscopes are used. To reduce the errors, three accelerometers can be used. In this case, however, the size and power consumption become too large to use in HMD system. The modified INS algorithm use the grid map and the characteristics of the human motions.