• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.921-932
• /
• 2010

Metropolitan railway headway is calculated and decided by external conditions such as appropriate level of service and competitiveness rather than passenger demand for the peak time which is based on transport passenger capability of train. On contrast of inter-city urban railways, train time intervals of sub-urban metropolitan railway were fixed more than 20 mins in the peak time which results in low level of convenience. Big gap of headway brings a vicious circle of deteriorating competitiveness and decreasing the number of customers. Also this time gap of train interval results in stagnation of passenger demand, and makes it difficult to reduce headway. This thesis is a basic research to identify headway problems and their solutions of metropolitan railway. This thesis suggests passenger demand and the calculated standard for setting the headway, and reviews the level of passenger crowdedness, the numbers of coach for each train and time-competitiveness. At the last, thesis suggests the need for making headway by means of train services throughout benefit & cost analysis. And it also recommends the improved calculating method of setting up headway considering the different train headway standards by regional situation, flexibility in the number of coaches for a train, government policy to activate railway business and the need for setting up the standard for train service level.

• Journal of Korean Society for Atmospheric Environment
• /
• v.33 no.1
• /
• pp.31-44
• /
• 2017

The aim of this study is to evaluate the accuracy and variability of the oak pollen concentrations over the Seoul metropolitan region (SMR) simulated by the Community Multiscale Air Quality (CMAQ)-based pollen dispersion model, which is the CMAQ-pollen model integrated with the improved oak pollen emission model(PEM-oak). The PEM-oak model developed is based on hourly emission flux parameterization that includes the effects of plant-specific release, meteorological adjustment, and diurnal variations of oak pollen concentrations. A 33 day-run for oak pollen simulation was conducted by the CMAQ-pollen model with a 3 km spatial resolution for the SMR during the 2014 spring pollen season. Modeled concentrations were evaluated against the hourly measurements at three Burkard sampling sites. Temporal variations of oak concentrations were largely well represented by the model, but the quantitative difference between simulations and measurements was found to be significant in some periods. The model results also showed that large variations in oak pollen concentrations existed in time and space and high concentrations in the SMR were closely associated with the regional transport under strong wind condition. This study showed the effective application of the CMAQ-pollen modeling system to simulate oak pollen concentration in the SMR. Our results could be helpful in providing information on allergenic pollen exposure. Further efforts are needed to further understand the oak pollen release characteristics such as interannual variation of the oak pollen productivity and its spatio-temporal flowering timing.

• Journal of Korean Society for Atmospheric Environment
• /
• v.34 no.1
• /
• pp.101-119
• /
• 2018

In this study, we analyzed long-term measurements and air quality simulation results of four criteria air pollutants ($PM_{10}$, $O_3$, $NO_2$, and $SO_2$) for 10 years, from 2006 to 2015, with emphasis on trends of annual variabilities. With the observation data, we conducted spatial interpolation using the Kriging method to estimate spatial distribution of pollutant concentrations. We also performed air quality simulations using the CMAQ model to consider the nonlinearity of the secondary air pollutants such as $O_3$ and the influence of long-range transport. In addition, these simulations are used to deduce the effect of long-term meteorological variations on trends of air quality changes because we fixed the emissions inventory while changing meteorological inputs. The nation-wide inter-annual variability of modeled $PM_{10}$ concentrations was $-0.11{\mu}g/m^3/yr$, while that of observed concentrations was $-0.84{\mu}g/m^3/yr$. For the Seoul Metropolitan Area, the inter-annual variability of observed $PM_{10}$ concentrations was $-1.64{\mu}g/m^3/yr$ that is two times rapid improvement compared to other regions. On the other hand, the inter-annual variability of observed $O_3$ concentrations is 0.62 ppb/yr which is larger than the simulated result of 0.13 ppb/yr. Magnitudes of differences between the modeled and observed inter-annual variabilities indicated that decreasing trend of $PM_{10}$ and increasing trend of $O_3$ are more influenced by emissions and oxidation states than meteorological conditions. We also found similar patterns in $NO_2$. However, $NO_2$ trends showed greater regional and seasonal differences than other pollutants. The analytic approach used in this study can be applicable to estimate changes in factors determining air quality such as emissions, weather, and surrounding conditions over a long term. Then analysis results can be used as important data for air quality management planning and evaluation of the chronic impact of air quality.

• Journal of Korean Society of Transportation
• /
• v.24 no.4 s.90
• /
• pp.7-17
• /
• 2006

The purpose or this paper is to investigate the relationship between highway improvement and Induced Travel Demand(ITD) focusing on the Seoul metropolitan area data. In addition, authors tried to estimate basic unit of demand elasticity focusing on zone and trip purpose which can be applied for the ITD forecasting. The results are based on the 2002 Metropolitan Household Transportation Survey Data, where the demand elasticity (DE) is -0.582 in Seoul, -0.597 in Incheon and -0.559 in Gyounggi province, respectively. This study revealed part of the relationship between highway improvement and ITD for metropolitan region and provided the framework for yielding real estimated values by applying the concept of demand elasticity in terms of the relationship by using regional and long-term data. We expect that the basic unit of demand elasticity focusing on zone and trip purpose can be applied for the ITD forecasting to analyze the whole demand exactly The estimated DE's for age group and day of week can also be used for Proper transportation management and transport Policy making. Some limitations have also been discussed.

• Atmosphere
• /
• v.29 no.5
• /
• pp.511-523
• /
• 2019

A new Korean Meteorological Administration (KMA) airborne measurement platform has been established for regular observations for scientific purpose over South Korea since late 2017. CRDS G-2401m analyzer mounted on the King Air 350HW was used to continuous measurement of CO₂, CH₄ and CO mole fraction. The total uncertainty of measurements was estimated to be 0.07 ppm for CO₂, 0.5 ppb for CH₄, and 4.2 ppb for CO by combination of instrument precision, repeatability test simulated in-flight condition and water vapor correction uncertainty. The airborne vertical profile measurements were performed at a regional Global Atmosphere Watch (GAW) Anmyeon-do (AMY) station that belongs to the Total Carbon Column Observing Network (TCCON) and provides concurrent observations to the Greenhouse Gases Observing Satellite (GOSAT) overpasses. The vertical profile of CO₂ shows clear altitude gradient, while the CH₄ shows non-homogenous pattern in the free troposphere over Anmyeon-do. Vertically averaged CO₂ at the altitude between 1.5 and 8.0km are lower than AMY surface background value about 7 ppm but higher than that observed in free troposphere of western pacific region about 4 ppm, respectively. CH₄ shows lower level than those from ground GAW stations, comparable with flask airborne data that was taken in the western pacific region. Furthermore, this study shows that the combination of CH₄ distribution in free troposphere and trajectory analysis, taking account of convective mixing, is a useful tool in investigating CH₄ transport processes from tropical region to Korean region in winter season.

• Environmental Analysis Health and Toxicology
• /
• v.21 no.1 s.52
• /
• pp.45-56
• /
• 2006

This study was conducted to investigate seasonal distributions of fine particles ($PM_{2.5}$) and associated polycyclic aromatic hydrocarbons (PAHs) at three cities. $PM_{2.5}$ samples were collected on glass fiber filters at urban (Chuncheon), metropolitan (Seoul), and industrial complex sites (Ulsan) from September, 2002 to February, 2004 using the Andersen FH 95 Particulate Sampler. About five 24-hour samples were collected from each site per season. The filters were analyzed for mass and six selected PAHs concentrations. $PM_{2.5}$ concentrations were the highest either in winter or spring, which could be attributed to the increase of fossil fuel combustion in winter or the transport of yellow sand to the Korean peninsula from China in spring, respectively. Regional $PM_{2.5}$ concentrations were higher in the order of Seoul>Chuncheon>Ulsan without statistical difference among cities. The filters were extracted using dichloromethane in an ultrasonicator and analyzed for six PAHs (anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, and benzo[a]pyrene) with HPLC. Total PAHs concentrations were statistically different among seasons in each site, and the highest concentrations were observed in winter at each sampling site. For total samples collected, the median total PAHs concentrations in Chuncheon ($4.6ng/m^3$) and Seoul ($4.4ng/m^3$) were approximately two times higher than that in Ulsan ($2.1ng/m^3$). Chrysene was a component found in the highest proportion among total PAHs at each site. Carcinogenic risks calculated based on the BaP toxic equivalency factors (TEFs) over the whole sampling period were higher in the order of Chuncheon>Seoul>Ulsan. This study suggests that the atmosphere of Chuncheon is contaminated with particulate matter and PAHs at the levels equivalent to those of Seoul and that an appropriate measure needs to be taken to mitigate human health risks from inhalation exposure to airborne fine particles.

• Journal of the Korean Geosynthetics Society
• /
• v.19 no.1
• /
• pp.75-82
• /
• 2020

There have been often cases of collapse for geogrid reinforced soil (GRS) retaining wall. Hence, social interest in the reinforcement and restoration of the collapsed GRS wall is increasing day by day. However, there are only few researches. For this reason, a series of numerical analyses using the Plaxis 2D program was conducted in this study to analyze the suitable reinforcement methods that can be applied on the existing damaged GRS wall caused by overturning of the modular blocks facing and the surface settlement at the backfill as the results from the design failure. The restoration plan used in this study is composed of two cases: (Case 1) soil nailing reinforcement and reinforced concrete (RC) wall facing construction on the existing damaged GRS wall; and (Case 2) removal of the entire damaged GRS wall and then reconstruction. The results on the internal stability of the GRS wall show that Case 1 obtained a greater safety factor than Case 2 for tensile force while Case 2 had a greater safety factor than Case 1 for pullout failures. Case 1 was found to be more stable than Case 2 in terms of the global slope safety by shear strength reduction method and the external deformation behavior by numerical analysis. In this study, the existing damaged GRS wall which was reinforced using Case 1 method shows more stable external behavior.

• Journal of the Korean Geographical Society
• /
• v.47 no.1
• /
• pp.13-36
• /
• 2012

This paper is to reconsider comprehensively and systematically major issues on transnational immigrants, increased rapidly since the beginning of the 1990s, and their impacts on socio-spatial changes in S. Korea. Foreign immigrants who have moved on the contexts of unevenness of globalization and advancces in transport & telecommunication technology on the global level and of economic development and shortage of cheap and unskilled workers have been distributed unevenly, concentrating on the Capital region and local areas with industrial complexes. Foreign workers seems to have some negative influences on regional economies in the long-term, though positive in the short-term. Domestic people seem to have an ambivalent attitude which accepts necessity of multi-culture, while simultaneously continues to be self-confident on ethnic homogeneity. The Korean government has launched multicultural policies for foreign immigrants by the mid-2000, but still continues some policies with assimilationism and differential exclusionism, marginalizing them socio-spatially, while lacking local government's policy and programmes. In conclusion, in order to resolve these problems and to transfer multicultural societal space of Korea, a geography of transnational migration which promotes especially discourse and policy with authentic multiculturalism, extending roles of local government, and ensuring glocal citizenships.

• The Journal of Bigdata
• /
• v.5 no.1
• /
• pp.109-124
• /
• 2020

In Korea, despite much interest in real estate, it is not easy to predict prices. Because apartments are both residential spaces and investment materials. Key figures affecting the price of apartments vary widely, and there are also regional characteristics. This study was conducted to derive the factors and characteristics that affect the sale price of apartments in S City, Gyeonggi-do. In general, people diagnose that better subway accessibility leads to higher apartment sales price. Nevertheless, in the case of S City, the price was slightly lower as it was closer to Line 1, but the higher the subway accessibility at Shinbundang Line, the higher the price. The five-year average of government bonds and the price were inversely related, and it was found to be proportional to the M2 balance and the price. The floor area ratio and the total number of parking lots had a great influence on the price, and the presence of department stores and discount marts within 1.5 km were the most important factors in the area of cultural aspect.

• Journal of Korea Port Economic Association
• /
• v.28 no.3
• /
• pp.27-44
• /
• 2012

The offshore wind farm is increasingly attractive as one of future energy sources all over the world. In addition, the capacity of an offshore wind turbine gets larger and its physical characteristics are big and heavy. In this regard, a special port is necessary to assemble, store, and transport the offshore wind systems, supporting to form the offshore wind farms. Thus, this study aims to provide a policy maker which evaluation factors can significantly affect to the optimal site selection of a offshore wind port. For this, Fuzzy-AHP method is applied to capture the relative weights. The results of this study can be summarized as follows. Five criteria in level I was defined such as the accumulation factor, the regional factor, the economic factor, the location factor, and the consortium factor. Of these, the accumulation factor(37.4%), the location factor(34.2%), and the economic factor( 24.5%) were analyzed by major factors. In level II, three assessment items of each factor were selected so that total fifteen items were formed. To sum up, the site selection of offshore wind port should consider the density of the wind industry, cargo volume of securing the economic operation of terminals, the development degree of offshore wind related industry, and the proximity to the offshore wind farms. In other words, the construction of offshore wind port should be paid attention to considering not only the proximity to offshore wind farms but also the preference of turbine manufacturing companies.