• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.40 no.6
• /
• pp.633-641
• /
• 2020

Residential complexes offer a sense of community and convenience, but making closed and privated space have been criticized.Closed urban spaces have issues encouraging residential segregation.large apartment complexes over 1,000 households,the most poular housing type in Korea, seems to make urban space more closed and privated than ever before. Our study puts forward and tests the hypothesis that large apartment complexes with over 1,000 households are linked to residential segregation. First of all, we examined the degree of residential segregation of metropolitan cities in Korea over a nine-year period (2011-2019). The dissimilarity index and the delta index were used for determining the extent of residential segregation. Next, we tested our hypothesis by Spearman's rank correlation analysis. Spearman's rank correlation analysis was performed on the residential segregation index per administrative division ("dong") and the number of large apartment complexes per administrative division ("dong").

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2018.11a
• /
• pp.157-158
• /
• 2018

In this study, the current tendency to replace a large amount of material admixture, which is fly ash (FA) and blast furnace slag (BS), into concrete is that high-grade cheese high admixture of high fluidity concrete In consideration of the substitution rate, we considered J-Ring to investigate the influence on the segregation resistance and the method of evaluating the classical segregation. In addition to the admixture replacement rate in the study results, the EIS using J-Ring became lower and the percentage of vehicles with segregation increased. Such a tendency is considered to be positive when J-Ring is used when segregation is judged if segregation degree is similar to EIS using J-Ring.

• Journal of the Economic Geographical Society of Korea
• /
• v.18 no.1
• /
• pp.1-16
• /
• 2015

It is widely believed that increasing socio-economic polarization inspired by globalization and economic restructuring worsens residential segregation by class in Korean cities. However, the existing literature falls short in showing the recent changes of the residential segregation, particularly after the 1997 financial crisis, with reliable and systematic segregation measures. Noting that there are the two major dimension in residential segregation - evenness-concentration and exposure-clustering - this study introduced not only global measure (dissimilarity index and isolation/interaction index) but also local measures (location quotient and Local Moran's I) for each dimension. These measures are applied to the case study of Seoul in the 2000s. The class is defined by education attainment and the data is obtain through the MicroData System Service System(MDSS). The result shows that the residential segregation by education attainment persists through 2000s and even get worse in some dimension. More significantly, it turns out that high-class and low-class residence are nearly mirror-images of each other, indicating high segregation.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2018.05a
• /
• pp.140-141
• /
• 2018

There are three types of high fluidity concrete: powder based, VMA based, and combined. In the case of the powder based high fluidity concrete mixture, according to the textbook, increased viscosity due to the replaced fly ash can prevent segregation of coarse aggregate. On the other hand, decreased density of the powder due to the fly ash replacement can causes segregation but there is no report on this issue. Therefore, in this research, the segregation resistance and segregation evaluation method for powder based high fluid concrete mixture are evaluated. As a result, with increased replacing ration of supplementary materials, EIS value was decreased and apparently segregation resistance was increased. However, from the compressive strength evaluation depending on height of the cylindrical specimen, it was confirmed that the different of strength difference between top and bottom part of the specimen. Thus, following research regarding vertical segregation should be studied.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2019.05a
• /
• pp.139-140
• /
• 2019

In this study, we considered the influence on segregation resistance at the time of substitution of FA and BS, which are substance admixtures of high fluidity concrete. According to the research results, EIS, which is an index of segregation in high fluidity concrete replacement, showed a low value, and the composition also showed a higher value than OPC. Therefore, it is confirmed that the resistance to segregation at the time of admixture replacement of high fluidity concrete is improved.

• Journal of the Korean Geographical Society
• /
• v.42 no.4
• /
• pp.616-631
• /
• 2007

Residential differentiation is an academic theme which has been given enormous attention in urban studies. This is due to the fact that residential segregation can be seen as one of the best indicators for socio-spatial dialectics occurring on urban space. Measuring how one population group is differentiated from the other group in terms of residential space has been a focal point in the residential segregation studies. The index of dissimilarity has been the most extensively used one. Despite its popularity, however, it has been accused of inability to capture the degree of spatial clustering that unevenly distributed population groups usually display. Further, the spatial indices of segregation which have been introduced to edify the problems of the index of dissimilarity also have some drawbacks: significance testing methods have never been provided; recent advances in spatial statistics have not been extensively exploited. Thus, the main purpose of the research is to devise a spatial separation measure which is expected to gauge not only how unevenly two population groups are distributed over urban space, but also how much the uneven distributions are spatially clustered (spatial dependence). The main results are as follows. First, a new measure is developed by integrating spatial association measures and spatial chi-square statistics. A significance testing method based on the generalized randomization test is also provided. Second, a case study of residential differentiation among groups by educational attainment in major Korean metropolitan cities clearly shows the applicability of the analytical framework presented in the paper.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.923-926
• /
• 2008

Currently more high flow and high performance concrete is used for construction of buildings in the world. However, when high flow and high performance concrete put high performance water reducing agent in quantity to improve flow, it has a negative effect on concrete structures since segregation arises from it though flow will be improved. There are naked-eye observation, coarse aggregate washing test, L Flow test for permeation among reinforcing rods and measurement of viscosity to judge concrete segregation resistance. However, it is difficult to apply them to practical affairs since they are very complicated and troublesome. Therefore, the study analyzed EIS dividing slump flow value into slump value, how to valuate concrete segregation resistance more easily, on the basis of the existing reference materials to propose EIS. As the results, in the event of high flow concrete, it is desirable that EIS value is prescribed to be less than 2.5 at the time of managing segregation. Also, at the time of prescribing EIS with performance, it is judged that it is desirable to manage segregation as less than 2.2 (Grade 1), 2.2$\sim$2.4 (Grade 2) and more than 2.6 (Grade 3).

• YAKHAK HOEJI
• /
• v.21 no.2
• /
• pp.95-100
• /
• 1977

The effects of the particle size on the homogeneity of mixing and segregation of caffeine-lactose (1:99) mixture were studied. Using the two kinds of caffein, milled and unmilled caffein, V-type blender, the degree of mixing according to the particle size was predicted and the experiment on the change of mixedness by mixing time was carried out by the method derived from mixing index theory by Poole et al. and Hersey. the results could be summarized as follows; (1) The homogeneity of mixing was greatly affected by the particle size and the particle size should be reduced to the adepuate level to attain the desirable mixedness. (2) The homogeneity was not proportional to the mixing time and optimum mixing time for caffein-lactose was about 10 minutes. (3) Segregation tendency was increased by the particle size increase and greatly affected by the flow time in the segregation cell.

• Journal of the Korean Regional Science Association
• /
• v.32 no.3
• /
• pp.17-27
• /
• 2016

In order to solve the problem of how to estimate the residential segregation, the Spatial Concentration Index(SCI) and Location quotient(LQ) are able to be one of alternative methods, and a comprehensive analysis of the residential segregation phenomenon in the seoul metropolitan area is the aim of the study. The results of SCI show that residential concentration areas in low-rent are some Gyeonggi-do's downtown(Bucheon-si, Suwon-si) as well as rural and urban-rural complex outskirts of the metropolitan area. The results of changing of SCI from 2011 to 2014, downward changes appeared thirteen districts and upward changes appeared fourteen districts. Especially downward change district was Sosa-gu, Bucheon-si and upward change district was Yeongtong-gu, Suwon-si. In conclusion, that high rent level groups are more concentration on specific area than low rent level groups. By decreasing residential concentration districts in low-rent level group, 'diversity' districts have been increasing in seoul metropolitan but the phenomenon of residential concentration in high and low level group have been being intensified. These results could be confirmed by quantitative through LQ. Methodologically LQ would strengthen the explanatory power of SCI, and ongoing research of SCI in conjunction with other quantitative methods will need.

• Journal of the Korean Geotechnical Society
• /
• v.26 no.4
• /
• pp.5-14
• /
• 2010

Three years of frost heave field experiments were conducted to evaluate a method for reducing heave using a recycled tire powder-soil mixture. By mixing Tomakomai soil with 20% recycled tire powder, frost heave amount was drastically decreased. The results of the field experiment confirm that recycled tire powder is an excellent material for use in controlling the total amount of heave. The restraining effect of a recycled tire powder-soil mixture is qualitatively analyzed based on amount of frost heave, frost heave ratio, thermal conductivity, permeability and segregation potential theory.