• Title/Summary/Keyword: Gravity Model

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Development of Advanced Gravity Model Using Accordance Rate Of Observed O-D Value and Derived O-D Value from Gravity Model (실측 O-D값과 중력모형 재현 O-D값의 일치비율을 이용한 개선 중력모형 개발)

  • Ryu, Yeong-Geun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.1
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    • pp.287-295
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    • 2013
  • This paper developed advanced gravity model for higher estimation accuracy, that deals with residuals. Previously studied paper using gravity model's residual, residual calculated that observed O-D value minus derived O-D value from gravity model, and this residual added to the target year's estimated value from gravity model. In this paper, residuals calculated on gravity model parameter estimation process, and this residual is revealed the same value that observed O-D value devided by derived O-D value from gravity model. And case study resulted that developed new gravity model that applied accordance rate of observed O-D value and derived O-D value from gravity model has higher estimation accuracy than other gravity models as basic gravity model and residual plused gravity model.

Development of an Improved Gravity Model using Residual (잔차를 이용한 개선 중력모형의 개발)

  • Ryu, Yeong Geun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.3D
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    • pp.417-424
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    • 2006
  • To get more accurate trip distribution estimation results, this study developed an improved gravity model. Using three different year's O-D table resulted from person trip survey, this study analyzed correlative between basic year's residuals and target year's residuals by gravity model. And resulted that the two have linear correlation. From this, improved gravity model was developed as adding basic year's residual to present gravity model. Developed gravity model was compared to present gravity model by estimation accuracy, and revealed that distributed trips from improved gravity model was more closer to real O-D than distributed trips from present gravity model.

Analysis Distribution and Feature of Lunar Gravity Field Using SGM90d Model (SGM90d모델을 이용한 달 중력장 분포 및 특징 분석)

  • Huang, He;Yun, Hong-Sic;Lee, Dong-Ha
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.27 no.2
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    • pp.129-138
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    • 2009
  • The lunar gravity field is an important source to understand the lunar interior structure, dichotomy and magma ocean of the moon, furthermore it can be used to study the origin and evolution history of the moon. In this paper, we firstly investigated the history of lunar exploration were performed for determining the lunar gravity field, in addition to investigating the procedure of progress related with the lunar gravity field model and gravity observations techniques. After, we determined practically the gravity anomalies of the moon using the new lunar gravity model, SGM90d (SELENE Gravity Model), which were developed by processing the tracking data from SELENE, the japanese lunar mission. Finally, we compared the lunar gravity anomalies from SGM90d model to the those from existing lunar gravity model (LP165P). As results from the comparison, we can make a sense that 4-way Doppler observations of SELENE is very effective to measure the gravity field on the farside of the moon. The precise lunar gravity field model including the farside of the moon which can be more helpful to understand the dichotomy of moon and to establish the detailed distribution of lunar gravity field, such as a mascon.

Precision Coordinate Transformation and Gravity Acceleration Algorithms (정밀좌표변환 및 중력가속도 계산 알고리듬 분석)

  • Kim, Jeong-Rae;Noh, Jeong-Ho
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.19 no.4
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    • pp.30-36
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    • 2011
  • Inertial navigation systems requires gravity model to compute gravity acceleration and its trajectory accuracy depends on the gravity model accuracy especially for a long range flight. The gravity model accuracy is important for satellite orbit prediction as well. The precision gravity model requires a precision coordinate transformation between inertial and Earth fixed coordinates. Precision gravity acceleration algorithms with a coordinate transform are studied and a computer program is developed. The effects of individual model components on trajectory error are analyzed.

Validity of Gravity Models for Individual Choies (개인별 선택행위에서의 동력모형의 유효성)

  • 음성직
    • Journal of Korean Society of Transportation
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    • v.1 no.1
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    • pp.43-47
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    • 1983
  • Within the conventional transportation planning process, "trip distribution" has a significant role to play. The most widely applied trip distribution model is the gravity model, for which Wilson provided the theoretical basis in 1967. The concept of the gravity model, however, still remains ambiguous if we analyze the "trip distribution" with a disaggregate data set. Thus, this paper hypothesizes that the gravity technique is still valid even with the disaggregate data set, by proving that the estimated coefficients of the gravity model, which is derived under the principle of entropy maximization, are identical with those of the multinomial logit model, which is derived under the principle of individual utility maximization.tility maximization.

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Improving the linear flexibility distribution model to simultaneously account for gravity and lateral loads

  • Habibi, AliReza;Izadpanah, Mehdi
    • Computers and Concrete
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    • v.20 no.1
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    • pp.11-22
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    • 2017
  • There are two methods to model the plastification of members comprising lumped and distributed plasticity. When a reinforced concrete member experiences inelastic deformations, cracks tend to spread from the joint interface resulting in a curvature distribution; therefore, the lumped plasticity methods assuming plasticity is concentrated at a zero-length plastic hinge section at the ends of the elements, cannot model the actual behavior of reinforced concrete members. Some spread plasticity models including uniform, linear and recently power have been developed to take extended inelastic zone into account. In the aforementioned models, the extended inelastic zones in proximity of critical sections assumed close to connections are considered. Although the mentioned assumption is proper for the buildings simply imposed lateral loads, it is not appropriate for the gravity load effects. The gravity load effects can influence the inelastic zones in structural elements; therefore, the plasticity models presenting the flexibility distribution along the member merely based on lateral loads apart from the gravity load effects can bring about incorrect stiffness matrix for structure. In this study, the linear flexibility distribution model is improved to account for the distributed plasticity of members subjected to both gravity and lateral load effects. To do so, a new model in which, each member is taken as one structural element into account is proposed. Some numerical examples from previous studies are assessed and outcomes confirm the accuracy of proposed model. Also comparing the results of the proposed model with other spread plasticity models illustrates glaring error produced due to neglecting the gravity load effects.

Comparison Study of O/D Estimation Methods for Building a Large-Sized Microscopic Traffic Simulation Network: Cases of Gravity Model and QUEEENSOD Method (대규모 미시교통시뮬레이션모형 구축을 위한 O/D 추정 방법 성능 비교 - 중력모형과 QUEENSOD 방법을 중심으로 -)

  • Yoon, Jung Eun;Lee, Cheol Ki;Lee, Hwan Pil;Kim, Kyung Hyun;Park, Wonil;Yun, Ilsoo
    • International Journal of Highway Engineering
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    • v.18 no.2
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    • pp.91-101
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    • 2016
  • PURPOSES : The aim of this study was to compare the performance of the QUEENSOD method and the gravity model in estimating Origin-Destination (O/D) tables for a large-sized microscopic traffic simulation network. METHODS : In this study, an expressway network was simulated using the microscopic traffic simulation model, VISSIM. The gravity model and QUEENSOD method were used to estimate the O/D pairs between internal and between external zones. RESULTS: After obtaining estimations of the O/D table by using both the gravity model and the QUEENSOD method, the value of the root mean square error (RMSE) for O/D pairs between internal zones were compared. For the gravity model and the QUEENSOD method, the RMSE obtained were 386.0 and 241.2, respectively. The O/D tables estimated using both methods were then entered into the VISSIM networks and calibrated with measured travel time. The resulting estimated travel times were then compared. For the gravity model and the QUEENSOD method, the estimated travel times showed 1.16% and 0.45% deviation from the surveyed travel time, respectively. CONCLUSIONS : In building a large-sized microscopic traffic simulation network, an O/D matrix is essential in order to produce reliable analysis results. When link counts from diverse ITS facilities are available, the QUEENSOD method outperforms the gravity model.

An Analysis of Spatial Differences in the Efficiency of Regional Industrial Enterprises in China

  • Qingsong Pang;Yanan Sun;Sangwook Kim
    • Journal of the Korea Society of Computer and Information
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    • v.29 no.1
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    • pp.263-271
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    • 2024
  • This paper analysis of spatial differences in the efficiency of regional industrial enterprises in China from 2011 to 2021. The efficiency analysis uses the DEA-CCR model. The input variables for efficiency analysis are total assets and annual average employees, and the output variables are revenue from principal business and total profits. Using trend surface analysis and gravity center model, to analysis the spatial differences of efficiency in different regions. From the results of the gravity center model, the coordinates of the gravity center of China's regional industrial enterprise efficiency in 2011 are 112.303°E & 34.239°N, and 2021 are 111.753°E & 33.791°N, which indicates that the gravity center of the efficiency of China's regional industrial enterprises in the 2011-2021 period generally moves to the southwest. From the results of the trend surface analysis, the efficiency of industrial enterprises in China's regional industrial enterprises appears to show spatial differences in both the eastwest and the northsouth directions.

The Precision Geoid Development based on Various Gravity Data (다양한 중력자료를 이용한 우리나라 정밀 지오이드 모델 개발)

  • Lee, Ji-Sun;Kwon, Jay-Hyoun;Keun, Young-Min
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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    • 2010.04a
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    • pp.35-37
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    • 2010
  • To construct precision geoid model, the gravity data having equal distribution and quality is necessary. In previous study, however, the geoid model has low precision since the biased distributed gravity data and some unverified data has been used and the gap between land and ocean exists. Now, the airborne and land gravity data was collected by various survey and the ship-borne gravity data and altimeter data has been achieved. Therefore, the precision geoid model development would be possible. And the GPS/Leveling data obtained by NGII could be used for construction of hybrid geoid in Korea. In this study, the procedure of geoid construction based on airborne, land, ship-borne and altimeter data using Remove-Restore technique will be explained. And the verification of gravimetric geoid and hybrid geoid would be introduced.

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3-D Gravity Terrain Inversion for High Resolution Gravity Survey (고정밀 중력 탐사를 위한 3차원 중력 지형 역산 기법)

  • Park, Gye-Soon;Lee, Heui-Soon;Kwon, Byung-Doo
    • Journal of the Korean earth science society
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    • v.26 no.7
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    • pp.691-697
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    • 2005
  • Recently, the development of accurate gravity-meter and GPS make it possible to obtain high resolution gravity data. Though gravity data interpretation like modeling and inversion has significantly improved, gravity data processing itself has improved very little. Conventional gravity data processing removes gravity effects due to mass and height difference between base and measurement level. But, it would be a biased density model when some or whole part of anomalous bodies exist above the base level. We attempted to make a multiquadric surface of the survey area from topography with DEM (Digital Elevation Map) data. Then we constituted rectangular blocks which reflect real topography of the survey area by the multiquadric surface. Thus, we were able to carry out 3-D inversions which include information of topography. We named this technique, 3-D Gravity Terrain Inversion (3DGTI). The model test showed that the inversion model from 3DGTI made better results than conventional methods. Furthermore, the 3-dimensional model from the 3DGTI method could maintain topography and as a result, it showed more realistic geologic model. This method was also applied on real field data in Masan-Changwon area. Granitic intrusion is an important geologic characteristic in this area. This method showed more critical geological boundaries than other conventional methods. Therefore, we concluded that in the case of various rocks and rugged terrain, this new method will make better model than convention ones.