Papers by Justin S. Chang
Journal of Korean Society of Transportation, 2017
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Atmospheric Pollution Research, 2020
Abstract For the first time, mobile campaign and building monitoring experiments were conducted i... more Abstract For the first time, mobile campaign and building monitoring experiments were conducted in downtown Seoul, Korea during the 2018/2019 winter period to assess the possibility of the co-benefit of CO2 emission reduction and air quality improvement. Given that CO2 and air pollutants in cities both originate from fossil fuel combustion, monitoring urban CO2 concentrations using a mobile vehicle and from the top of tall buildings can be a potentially effective approach for diagnosing the air quality. The local enhancement values (△species) related to urban emission sources were estimated by eliminating baseline concentrations. The results obtained showed high correlation coefficients between △CO2 and △air pollutants (i.e., 0.753, 0.505, and 0.525 for △CO, △NOX, and △NO2), confirming the applicability of CO2 as an indicator of air pollutant sources in downtown Seoul. The evaluation of the air quality in the study area using air pollutant ratios, including the ratios of CO and NOX/NO2, relative to CO2 showed that the ratios of △CO, △NOX, and △NO2 relative to △CO2 were 5.76, 1.89, and 0.21 ppb ppm−1. The estimated △NO2/△NOX ratio (11%) and a comparison of the △NOX/△CO2 ratios obtained with those reported for other cities in different countries suggested the possibility of a relationship between the current air quality in downtown Seoul and the use of diesel vehicles. Results suggest that the development of municipal policies aimed at mitigating climate change should consider the co-benefit of air quality improvement so as to ensure the effective reduction of CO2 and air pollutant emissions.
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Transportation Research Procedia, 2020
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International Journal of Injury Control and Safety Promotion, 2020
Abstract Road safety performance varies among local municipalities since road safety involves mul... more Abstract Road safety performance varies among local municipalities since road safety involves multiple inputs (e.g. facilities and programs) and multiple outputs (e.g. crashes and casualties). A benchmark analysis between local governments is a useful platform to improve their road safety performances because the analysis can specify which other municipalities’ processes should be consulted to improve their practices. This study employs the data envelopment analysis approach for benchmark analysis. The input-oriented variable returns to scale model is applied to Korea. The outputs are the numbers of crashes and fatalities, and two sets of indexed inputs comprising institutional managements and governmental interventions are visited. In particular, standardized data formatting between, and controllability by, local governments are highlighted as the required properties for inputs. The overall efficiency scores and the nature of returns to scale reveal the under-investments in road safety in Korea. Efficiency scores by each municipality are also provided. This examination shows the projected values of inputs and outputs as well as benchmarks for each municipality. A sensitivity analysis based on the leave-one-out method generates stable efficiency scores across local governments, which shows the robustness of the model. Finally, the incorporation of environmental variables and dynamic analysis is suggested for further studies.
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Transportation Planning and Technology, 2019
ABSTRACT Excess commuting refers to wasteful journey-to-work travel, resulting from the non-optim... more ABSTRACT Excess commuting refers to wasteful journey-to-work travel, resulting from the non-optimal spatial configuration of residences and workplaces. Traditionally, this concept has been employed to analyse the efficiency of the urban structure. This paper, however, examines the spatial equity of excess commuting, which is an essential component of a sustainable urban transport system. The Gini coefficient and GIS mapping are used to measure this spatial equity, supported by data from Seoul’s Tmoney transit card system. Results show the vulnerable regions in terms of horizontal equity of excess commuting in Seoul. Transit supply and jobs-housing balance are identified as the core factors affecting excess commuting in relation to spatial disparities. However, an evaluation of Seoul’s ambitious plan of light-rail construction is considered to be not very helpful in mitigating the current spatial inequality of excess commuting in the city.
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Journal of Korea Planning Association, 2016
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International Journal of Urban Sciences, 2019
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Journal of Tourism Studies, 2016
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Transportmetrica A: Transport Science, 2017
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Transportation Letters, 2016
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This study examines the ramp-up analysis techniques which have been introduced till now and prese... more This study examines the ramp-up analysis techniques which have been introduced till now and presents the strength and weakness of each method. The applicability of each technique was reviewed using a case study involving the data of Cheonan-Nonsan motorway usages where seasonal variations of the data were removed. The results showed that all the techniques except F-test have the same ramp-up period of 12 months. The level of Tamp-up was 65%-72% compared to that of the real traffic volume at the beginning of opening. The demand recovered to the stabilized level as time goes on. To apply the methodology to practical demand forecasts actual surveys of real data of traffic demand should be performed. With these efforts to the patronage ramp-up, more reliable demand analyses can be accompanied.
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Journal of Korean Society of Transportation, 2012
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Journal of Korean Society of Transportation, 2014
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International Journal of Urban Sciences, 2014
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Transportation Letters, 2014
ABSTRACT
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Transportation Research Record: Journal of the Transportation Research Board, 2010
This paper deals with a novel patronage ramp-up analysis model. The ramp-up effect represents the... more This paper deals with a novel patronage ramp-up analysis model. The ramp-up effect represents the delay in ridership take-up during the first periods of new transport services or facilities. This influence is known as one of the external errors of transport demand forecasts, which degrades the reliability of demand studies and economic appraisal for transport schemes. Traditionally, professional judgment and regression analyses have been used to investigate this effect, but the existing methodologies suffer from the inherent limitations of being biased and arbitrary. In this paper, a heuristic F-test is suggested as an alternative framework. The model proposed is tested with road and rail schemes of South Korea. The case studies illustrate the ability of the model to find the ramp-up parameters involving the duration and the ratio of this effect. Subsequently, a numerical example of cost-benefit analysis including ridership ramp-up is provided. The experiment shows that incorporatin...
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Transportation Research Part D: Transport and Environment, 2013
The paper offers a valuation of urban rail noise in South Korea using the hedonic pricing method.... more The paper offers a valuation of urban rail noise in South Korea using the hedonic pricing method. It considers trade-offs in the context of housing prices, locality, and environment intrusion. The model adopted provides a reasonable explanation of the determinants of property values, with a unit increase in dB(A) decreases property value by 0.53% in the Seoul area.
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Journal of Urban Planning and Development, 2021
Abstract Pedestrian crosswalks are not always placed at optimal locations, and some crosswalks ca... more Abstract Pedestrian crosswalks are not always placed at optimal locations, and some crosswalks cause walkers to detour from their shortest routes. Some walkers run the risk of jaywalking to avoid d...
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Papers by Justin S. Chang