• Title/Summary/Keyword: Data validation

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Development of Stem Profile and Taper Equation for Carpinus laxiflora in Jeju Experimental Forests of Korea Forest Research Institute (국립산림과학원 제주시험림의 서어나무 수간형태와 수간곡선식 추정)

  • Chung, Young-Gyo;Kim, Dae-Hyun;Kim, Cheol-Min
    • Journal of agriculture & life science
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    • v.44 no.4
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    • pp.1-7
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    • 2010
  • Data was collected to develop equation for predicting stemp taper for Carpinus laxiflora in Jeju Experimental Forests. The Models tested for choosing the best-fit equations were Max & Burkhart's model, Kozak's model, and Lee's model. Performance of the equations in predicting stem diameter at a specific point along a stem was evaluated with fit and validation statistics and distribution of residuals on predicted values. In result, all the three models gave slightly better values of fitting statistics. In plotting residuals against predicted diameter, Max & Burkhart's model showed underestimation in predicting small diameter and Lee's Model did the same in predicting small diameter. Based on the above analysis of the three models in predicting stem taper, Kozak's model was chosen for the best-fit stem taper equations, and its parameters were given for C. laxiflora. Kozak's model was used to develop a stem volume table of outside bark for C. laxiflora.

Landslide Detection and Landslide Susceptibility Mapping using Aerial Photos and Artificial Neural Networks (항공사진을 이용한 산사태 탐지 및 인공신경망을 이용한 산사태 취약성 분석)

  • Oh, Hyun-Joo
    • Korean Journal of Remote Sensing
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    • v.26 no.1
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    • pp.47-57
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    • 2010
  • The aim of this study is to detect landslide using digital aerial photography and apply the landslide to landslide susceptibility mapping by artificial neural network (ANN) and geographic information system (GIS) at Jinbu area where many landslides have occurred in 2006 by typhoon Ewiniar, Bilis and Kaemi. Landslide locations were identified by visual interpretation of aerial photography taken before and after landslide occurrence, and checked in field. For landslide susceptibility mapping, maps of the topography, geology, soil, forest, lineament, and landuse were constructed from the spatial data sets. Using the factors and landslide location and artificial neural network, the relative weight for the each factors was determinated by back-propagation algorithm. As the result, the aspect and slope factor showed higher weight in 1.2-1.5 times than other factors. Then, landslide susceptibility map was drawn using the weights and finally, the map was validated by comparing with landslide locations that were not used directly in the analysis. As the validation result, the prediction accuracy showed 81.44%.

Validation and selection of GCPs obtained from ERS SAR and the SRTM DEM: Application to SPOT DEM Construction

  • Jung, Hyung-Sup;Hong, Sang-Hoon;Won, Joong-Sun
    • Korean Journal of Remote Sensing
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    • v.24 no.5
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    • pp.483-496
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    • 2008
  • Qualified ground control points (GCPs) are required to construct a digital elevation model (DEM) from a pushbroom stereo pair. An inverse geolocation algorithm for extracting GCPs from ERS SAR data and the SRTM DEM was recently developed. However, not all GCPs established by this method are accurate enough for direct application to the geometric correction of pushbroom images such as SPOT, IRS, etc, and thus a method for selecting and removing inaccurate points from the sets of GCPs is needed. In this study, we propose a method for evaluating GCP accuracy and winnowing sets of GCPs through orientation modeling of pushbroom image and validate performance of this method using SPOT stereo pair of Daejon City. It has been found that the statistical distribution of GCP positional errors is approximately Gaussian without bias, and that the residual errors estimated by orientation modeling have a linear relationship with the positional errors. Inaccurate GCPs have large positional errors and can be iteratively eliminated by thresholding the residual errors. Forty-one GCPs were initially extracted for the test, with mean the positional error values of 25.6m, 2.5m and -6.1m in the X-, Y- and Z-directions, respectively, and standard deviations of 62.4m, 37.6m and 15.0m. Twenty-one GCPs were eliminated by the proposed method, resulting in the standard deviations of the positional errors of the 20 final GCPs being reduced to 13.9m, 8.5m and 7.5m in the X-, Y- and Z-directions, respectively. Orientation modeling of the SPOT stereo pair was performed using the 20 GCPs, and the model was checked against 15 map-based points. The root mean square errors (RMSEs) of the model were 10.4m, 7.1m and 12.1m in X-, Y- and Z-directions, respectively. A SPOT DEM with a 20m ground resolution was successfully constructed using a automatic matching procedure.

Aerosol Optical Thickness Retrieval Using a Small Satellite

  • Wong, Man Sing;Lee, Kwon-Ho;Nichol, Janet;Kim, Young J.
    • Korean Journal of Remote Sensing
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    • v.26 no.6
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    • pp.605-615
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    • 2010
  • This study demonstrates the feasibility of small satellite, namely PROBA platform with the compact high resolution imaging spectrometer (CHRIS), for aerosol retrieval in Hong Kong. The rationale of our technique is to estimate the aerosol reflectances by decomposing the Top of Atmosphere (TOA) reflectances from surface reflectance and Rayleigh path reflectances. For the determination of surface reflectances, the modified Minimum Reflectance Technique (MRT) is used on three winter ortho-rectified CHRIS images: Dec-18-2005, Feb-07-2006, Nov-09-2006. For validation purpose, MRT image was compared with ground based multispectral radiometer measurements and atmospherically corrected Landsat image. Results show good agreements between CHRIS-derived surface reflectance and both by ground measurement data as well as by Landsat image (r>0.84). The Root-Mean-Square Errors (RMSE) at 485, 551 and 660nm are 0.99%, 1.19%, and 1.53%, respectively. For aerosol retrieval, Look Up Tables (LUT) which are aerosol reflectances as a function of various AOT values were calculated by SBDART code with AERONET inversion products. The CHRIS derived Aerosol Optical Thickness (AOT) images were then validated with AERONET sunphotometer measurements and the differences are 0.05~0.11 (error=10~18%) at 440nm wavelength. The errors are relatively small compared to those from the operational moderate resolution imaging spectroradiometer (MODIS) Deep Blue algorithm (within 30%) and MODIS ocean algorithm (within 20%).

Perspectives on the Applicatio of Remote Sensing for Observation of Ocean Environments (해양환경관측을 위한 원격탐사의 활용과 그 전망)

  • 유신재;정종철
    • Korean Journal of Remote Sensing
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    • v.15 no.3
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    • pp.277-288
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    • 1999
  • The aim of this review is to provide perspectives on the application of remote sensing techniques for observation of marine environmental changes on various spatio-temporal scales. Currently available remote sensing technologies are reviewed and future direction is suggested. For better utilization of remote sensing, a comprehensive plan should be developed by a demand-side and problem-solving approach. Marine environmental changes should be observed on proper spatio-temporal scales where the processes occur. For appropriate observation and monitoring of various environmental changes in coastal regions, more sensors must be utilized. Platforms other than satellites should also be utilized to expand the spatio-temporal scales of observation. Calibration/validation activities, required for accurate interpretation of remotely sensed data, could utilize buoys and ship-of-opportunity sensors. It is desirable that such systems by developed as a part of an integrated monitoring network.

The Study on the Extraction of the Distribution Potential Area of Debris Landform Using Fuzzy Set and Bayesian Predictive Discriminate Model (퍼지집합과 베이지안 확률 기법을 이용한 암설사면지형 분포지역 추출에 관한 연구)

  • Wi, Nun-Sol;JANG, Dong-Ho
    • Journal of The Geomorphological Association of Korea
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    • v.24 no.3
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    • pp.105-118
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    • 2017
  • The debris slope landforms which are existent in Korean mountains is generally on the steep slopes and mostly covered by vegetation, it is difficult to investigate the landform. Therefore a scientific method is required to come up with an effective field investigation plan. For this purpose, the use of Remote Sensing and GIS technologies for a spatial analysis is essential. This study has extracted the potential area of debrisslope landform formation using Fuzzy set and Bayesian Predictive Discriminate Model as mathematical data integration methods. The first step was to obtain information about debris locations and their related factors. This information was verified through field investigation and then used to build a database. In the second step, the map that zoning the study area based on the degree of debris formation possibility was generated using two modeling methods, and then cross validation technique was applied. In order to quantitatively analyze the accuracy of two modeling methods, the calculated potential rate of debrisformation within the study area was evaluated by plotting SRC(Success Rate Curve) and calculating AUC(Area Under the Curve). As a result, the prediction accuracy of Fuzzy set model wes 83.1% and Bayesian Predictive Discriminate Model wes 84.9%. It showed that two models are accurate and reliable and can contribute to efficient field investigation and debris landform management.

Development and Application of the Korean Prototype of Wellness Index (한국형 웰니스 인덱스 원안 개발과 적용)

  • Lee, Insook;Bang, Kyung-Sook;Kim, Sungjae;Lee, Juna;Jo, Juhyun
    • Perspectives in Nursing Science
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    • v.16 no.2
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    • pp.84-97
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    • 2019
  • Purpose: This study aimed to develop the Korean Prototype of Wellness Index (KP-WI) and identify the relationship between Koreans' health characteristics and wellness. Methods: The Wellness Index (WI) was translated into the primitive version of the KP-WI, considering the Koreans' culture and health behavior. It was administered to 223 service industrial employees at one workplace along with the Positive Affect and Negative Affect Schedule (PANAS) and Stress Questionnaire-Short Form. Data analyses included item-total correlation, Pearson's correlation coefficient, independent t-test, and one-way ANOVA. Results: The primitive version was modified to KP-WI based on the item-total correlation. The items considered to lower the reliability of the KP-WI were eliminated. Cronbach's ${\alpha}$ for each subscale ranged from .857 to .939. Perceived stress and negative emotions correlated significantly with wellness measured by KP-WI (r=-.29, p<.001; r=-.27, p<.001). Positive emotions correlated significantly with wellness (r=.60, p<.001). Conclusion: This study contributes to the development of Korean-style wellness indexes by developing a prototype and exploring the factors related to wellness.

The Analysis of Flood in an Ungauged Watershed using Remotely Sensed and Geospatial Datasets (I) - Focus on Estimation of Flood Discharge - (원격탐사와 공간정보를 활용한 미계측 유역 홍수범람 해석에 관한 연구(I) - 홍수량 산정을 중심으로 -)

  • Son, Ahlong;Kim, Jongpil
    • Korean Journal of Remote Sensing
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    • v.35 no.5_2
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    • pp.781-796
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    • 2019
  • This study attempted to simulate the flood discharge in the Duman River basin containing Hoeryong City and Musan County of North Korea where were damaged from Typhoon Lionrock on August, 2016. For hydrological modelling remotely sensed datasets were used to estimate watershed properties and hydrologic factors because the basin is ungauged where hydrological observation is not exist or sparse. For validation we applied our methodology and datasets to the Soyanggang Dam basin. It has not only similar shape factor and compactness ratio to those of the target basin but also accurate, adequate, and abundant measurements. The results showed that the flood discharge from Typhoon Lionrock corresponded to three to five years design floods in the Duman River basin. This indicate that the Duman River basin has a high risk of flood in the near future. Finally this study demonstrated that remotely sensed data and geographic information could be utilized to simulate flood discharge in an ungauged watershed.

Development of Soil Organic Carbon Storage Estimation Model Using Soil Characteristics (토양 특성을 이용한 토양유기탄소저장량 산정 모형 개발)

  • Lee, Taehwa;Kim, Sangwoo;Shin, Yongchul;Jung, Younghun;Lim, Kyoung-Jae;Yang, Jae E;Jang, Won Seok
    • Journal of The Korean Society of Agricultural Engineers
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    • v.61 no.6
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    • pp.1-8
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    • 2019
  • Carbon dioxide is one of the major driving forces causing climate changes, and many countries have been trying to reduce carbon dioxide emissions from various sources. Soil stores more carbon dioxide(two to three times) amounts than atmosphere indicating that soil organic carbon emission management are a pivotal issue. In this study, we developed a Soil Organic Carbon(SOC) storage estimation model to predict SOC storage amounts in soils. Also, SOC storage values were assessed based on the carbon emission price provided from Republic Of Korea(ROK). Here, the SOC model calculated the soil hydraulic properties based on the soil physical and chemical information. Base on the calculated the soil hydraulic properties and the soil physical chemical information, SOC storage amounts were estimated. In validation, the estimated SOC storage amounts were 486,696 tons($3.526kg/m^2$) in Jindo-gun and shown similarly compared to the previous literature review. These results supported the robustness of our SOC model in estimating SOC storage amounts. The total SOC storage amount in ROK was 305 Mt, and the SOC amount at Gyeongsangbuk-do were relatively higher than other regions. But the SOC storage amount(per unit) was highest in Jeju island indicating that volcanic ashes might influence on the relatively higher SOC amount. Based on these results, the SOC storage value was shown as 8.4 trillion won in ROK. Even though our SOC model was not fully validated due to lacks of measured SOC data, our approach can be useful for policy-makers in reducing soil organic carbon emission from soils against climate changes.

Numerical simulation of wind loading on roadside noise mitigation structures

  • TSE, K.T.;Yang, Yi;Shum, K.M.;Xie, Zhuangning
    • Wind and Structures
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    • v.17 no.3
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    • pp.299-315
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    • 2013
  • Numerical research on four typical configurations of noise mitigation structures and their characteristics of wind loads are reported in this paper. The turbulence model as well the model parameters, the modeling of the equilibrium atmospheric boundary layer, the mesh discretization etc., were carefully considered in the numerical model to improve the numerical accuracy. Also a numerical validation of one configuration with the wind tunnel test data was made. Through detailed analyses of the wind load characteristics with the inclined part and the wind incidence angle, it was found that the addition of an inclined part to a noise mitigation structure at-grade would affect the mean nett pressure coefficients on the vertical part, and that the extent of this effect depends on the length of the inclined part itself. The magnitudes of the mean nett pressure coefficients for both the vertical part and the inclined part of noise mitigation structure at-grade tended to increase with length of inclined part. Finally, a comparison with the wind load code British/European Standard BS EN 1991-1-4:2005 was made and the envelope of the mean nett pressure coefficients of the noise mitigation structures was given for design purposes. The current research should be helpful to improve current wind codes by providing more reasonable wind pressure coefficients for different configurations of noise mitigation structures.