• 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.

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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.

The Factors Affecting Kyrgyzstan's Bilateral Trade: A Gravity-model Approach

  • Allayarov, Piratdin;Mehmed, Bahtiyar;Arefin, Sazzadul;Nurmatov, Norbek
    • The Journal of Asian Finance, Economics and Business
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    • v.5 no.4
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    • pp.95-100
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    • 2018
  • The study investigates the factors that affect Kyrgyzstan's bilateral trade flows with its main trading partners and attempts to predict trade potential for Kyrgyzstan. Using panel data, the gravity model is applied to estimate Kyrgyzstan's trade from 2000 to 2016 for its 35 main trading partners. The coefficients derived from the gravity-model estimation are then used to predict trade potential for Kyrgyzstan. Results proved to be successful and explained 63% of the fluctuations in Kyrgyzstan's trade. According to the results, Kyrgyzstan's and its partners' GDP have a positive effect on trade, while distance and partners' population prove to have a negative effect. Predicted trade potential reveals that neighboring countries (China, Kazakhstan, Uzbekistan, and Tajikistan) and Russia still have a significant trade potential. Kyrgyzstan, being a less developed economy, even by Central Asia standards, can only achieve its goals of reducing poverty and becoming more developed by increasing its overall trade with the rest of the world. Therefore, it is essential to study the main determinants of Kyrgyzstan's bilateral trade. In this way, we can help policy makers formulate policies to expand Kyrgyzstan's trade. This study is the first attempt to apply to the gravity model to Kyrgyzstan in an attempt to predict trade potential.

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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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.

A Study on Inner Zone Trip Estimation Method in Gravity Model (중력모형에서 존내 분포통행 예측방법에 관한 연구)

  • Ryu, Yeong Geun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.5D
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    • pp.763-769
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    • 2006
  • Gravity Model estimates target year's distributed trips using three variables like as origin zone's trip production, destination zone's trip attraction and traffic impedance between origin zone centroid and destination zone centroid. Estimating inner zone trip by gravity model is impossible because traffic impedance of inner zone has "0" value. So till today, for estimating inner zone trips, other methods like growth factor model are used. This study proposed inner zone trip estimation method that calculates inner zone's traffic impedance using established gravity model and estimates inner zone trips by putting calculated traffic impedance into the gravity model. 1988 year's surveyed O-D as basic year's O-D, proposed method's and existing methods(growth factor method and regression model)'s estimated results of 1992 year's and 2004 year's were compared with each year's real O-D by $x^2$, RMSE, Correlation coefficient. And resulted that the proposed method is superior than other existing methods.

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A Study on the Utilization of Arbitration for Promoting Trade in the South American Market (남미시장 교역 활성화를 위한 중재 활용방안에 관한 연구)

  • Ahn, Tae-Kun;Kim, Sung-Ryong
    • Journal of Arbitration Studies
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    • v.26 no.2
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    • pp.91-114
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    • 2016
  • The purpose of this study is to promote trade between Korea and South American countries. Korea's trade with South America has decreased recently. This study analyzed the effects of arbitration on trade between Korea and South America. To this end, we conducted an analysis of the gravity model of trade between Korea and South America. The gravity model is a research method that is widely used to analyze the pattern of international trade. The dependent variables of the gravity model were trade in Korea and South America. The independent variables were GDP, population, and distance between Korea and South America. In addition, dummy variables were the FTA and whether to join the New York Convention or Washington Convention. Joining either Convention indicated the establishment of an international arbitration system. As a result, an arbitration system appeared to be effective in increasing trade. Depending on the results it shows the importance of utilizing the system of arbitration in South America. So this study analyzed the current status of arbitration in South America. To companies doing business in South America it provided the implications for an arbitration system there. Also it proposed a method for increasing trade for the Korean government and institutions.

A Green House Gas Emission Estimation Based on Gravity Model and Its Elasticity (중력모형을 이용한 온실가스 배출량추정 및 탄력성분석)

  • Im, Yong-Taek
    • Journal of Korean Society of Transportation
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    • v.29 no.4
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    • pp.85-93
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    • 2011
  • Many policies, such as transit-oriented development, encouraged use of bicycle and pedestrian, reduction of green house gas (GHG) and etc., have been deployed to support transport sustainability. Although various studies regarding GHG were presented, no one has yet adequately explained the behavior of travelers. This paper proposes a GHG emission model by highlighting its sensitivity, elasticity with regard to such travel cost as travel time, travel fare, and GHG pricing, introduced to reduce the amount of GHG in transportation system. For better estimation of GHG, the proposed model adopts (1) a production-constrained gravity model and (2) the travel distance from the origin and the destination (OD). The gravity model has a merit that it considers travel pattern between OD pairs. The model was tested with an example, and the promising results confirmed its validation and applications.

A gravity Model For The Catchments Between Parks (도시 근린공원간의 포착력에 대한 동력모형검증)

  • 권상준;심경구
    • Journal of the Korean Institute of Landscape Architecture
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    • v.21 no.2
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    • pp.1-7
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    • 1993
  • This study suggests one hypothesis: The strength between the catchment foreces of urban community parks can be represented to a gravity model. The gravity model is derived from the related of two subjects, witch is related with their distance. A grvity model for the catchments between parks is represented as followed formula: Iij=${\alpha}$${\times}$ $\frac{Pi$.$Pj}{${\beta}$r}$(formula) Here, Iij is a total number of the vistors of park i and j in a year. Pi is population of the catchment area of park i. Pj is population of the catchment area of park j. ${\alpha}$and, ${\beta}$ are parameters. This formula is testified in the case of Chong-ju community parks.

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