• Tunnel and Underground Space
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• v.31 no.1
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• pp.10-24
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• 2021

Rock mass classification for construction of underground facilities is essential to secure their stabilities. Therefore, the reliable values for rock mass classification from the precise information on rock discontinuities are most important factors, because rock mass discontinuities can affect exclusively on the physical and mechanical properties of rock mass. The conventional classification operation for rock mass has been usually performed by hand mapping. However, there have been many issues for its precision and reliability; for instance, in large-scale survey area for regional geological survey, or rock mass classification operation by non-professional engineers. For these reasons, automated rock mass classification using LiDAR becomes popular for obtaining the quick and precise information. But there are several suggested algorithms for analyzing the rock mass discontinuities from point cloud data by LiDAR scanning, and it is known that the different algorithm gives usually different solution. Also, it is not simple to obtain the exact same value to hand mapping. In this paper, several discontinuity extract algorithms have been explained, and their processes for extracting rock mass discontinuities have been simulated for real rock bench. The application process for several algorithms is anticipated to be a good reference for future researches on extracting rock mass discontinuities from digital point cloud data by laser scanner, such as LiDAR.

• Journal of Environmental Health Sciences
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• v.47 no.4
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• pp.339-355
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• 2021

Background: Particulate matter (PM₁₀, PM_2.5) and black carbon contribute to poor air quality in urban areas, and can also affect indoor environments. Exposure to PM can be associated with respiratory and lung diseases. Objectives: This study investigated the indoor and outdoor concentration distribution patterns of PM₁₀, PM_2.5, and black carbon at an apartment building, a typical residential space in the metropolitan areas of South Korea, by season, day of the week (weekday vs. weekend), and time of the day. It aims to obtain foundational data for the effective management of pollutants and investigate the difference in pollution levels between indoor and outdoor environments. Methods: Indoor and outdoor concentrations of PM and black carbon were measured at an apartment building located in Namyangju, Gyeonggi-do Province, using dust sensors and an Aethalometer AE51 (AethLabs, San Francisco, CA, USA) over the course of a year from June 2020 to May 2021. The concentration distribution patterns were analyzed by season and time of day. Results: PM₁₀ and PM_2.5 concentrations in the outdoor environment were higher than those in the indoor environment, regardless of the season. By contrast, the indoor black carbon concentration was higher than that in the outdoor environment during summer and autumn. The concentrations of PM₁₀, PM_2.5 and black carbon were found to be higher on weekdays than during weekends, especially during rush hour, with concentrations of 25.92~56.58 ㎍/m³, 21.12~44.82 ㎍/m³, 0.63~3.40 ㎍/m³. Conclusions: The outdoor concentrations of PM₁₀, PM_2.5, and black carbon were higher during the weekdays, especially during rush hour, than during weekends. This study is expected to provide basic data for the health management of apartment occupants because it is measured over a period of more than one year.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.39 no.6
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• pp.571-585
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• 2021

Various studies have analyzed urban decline at a universal level using the general characteristics of declining cities. However, urban decline at the city level should be considered because this decay occurs based on the unique attributes of a particular city. In addition, since this phenomenon occurs and spreads in microspaces, studies should consider smaller spatial units continuously. This study aims to develop an urban decline measurement model that considers regional characteristics to analyze the urban decline of Ulsan Metropolitan City over time and space. The index value of Ulsan, compared to the national average, is calculated and reflected in the weight to reflect regional characteristics in the model. In addition, after analyzing urban decline by administrative dong units, we also performed analysis by counting district units using spatial hierarchical structure to demonstrate evaluation on smaller unit spaces. As a result of analyzing urban decline patterns by associating the index calculated using the model with the social phenomenon of Ulsan Metropolitan City, urban decline formed clusters and spread to adjacent regions over time. In addition, results confirmed that external factors such as new towns and urban regeneration projects affect urban decline. By illustrating the degree of urban decline proposed measurement model used in this study, it is possible to present the priority of areas required for urban regeneration projects. Results are also helpful to test the effectiveness of completed or presently-implemented urban regeneration projects.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.561-577
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• 2021

The compacted bentonite buffer in a geological repository for high-level radioactive waste disposal is saturated due to groundwater inflow. Saturation of the bentonite buffer results in bentonite swelling and bentonite penetration into the rock discontinuities present around the disposal hole. The penetrated bentonite is exposed to groundwater flow and can be eroded out of the repository, resulting in bentonite mass loss which can affect the physical integrity of the engineered barrier system. Hence, the evaluation of buffer-rock interactions and coupled behavior due to groundwater inflow and bentonite penetration is necessary to ensure long-term disposal safety. In this study, the effects of the bentonite penetration and swelling on the physical properties of jointed rock mass were evaluated using the quasi-static resonant column test. Jointed rock specimens with bentonite penetration were manufactured using Gyeongju bentonite and hollow cylindrical granite rock discs obtained from the KAERI underground research tunnel. The effects of vertical stress and saturation were assessed using the P-wave and S-wave velocities for intact rock, jointed rock and jointed rock with bentonite penetration specimens. The joint normal and joint shear stiffnesses of each joint condition were inferred from the wave velocity results assuming an equivalent continuum. The joint normal and joint shear stiffnesses obtained from this study can be used as input factors for future numerical analysis on the performance evaluation of geological waste disposal considering rock discontinuities.

• Land and Housing Review
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• v.13 no.2
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• pp.65-79
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• 2022

To suggest implications of future housing problems, this study investigates which characteristics affect the housing satisfaction of young single households. Using the survey data, we perform the multiple regression and decision tree models based on the SPSS Statistics 25.0. Our empirical results show several key features. First, housing characteristics and intention to continue single households had a positive (+) effect on housing satisfaction, in the order of natural, housing, physical characteristics, and intention to continue single households. Second, housing characteristics and intention to marry in the future had a positive (+) effect on housing satisfaction in the order of natural, housing, and physical characteristics. Third, housing characteristics and intention to increase household members in the future had a positive (+) effect on housing satisfaction, in the order of natural, housing, and physical characteristics satisfaction. Finally, the results of the decision tree model show that the natural characteristics were over 3.4, and housing satisfaction was the highest in the case of Jeonse. The results of this study provide three implications for policymakers. First, improving the residential environment of young single households is important. Second, providing customized housing for young single households could enhance the housing satisfaction of young people. Finally, housing provision needs to be carried out with suitable space for the lifestyle of young single households.

• SUVANNABHUMI
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• v.14 no.2
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• pp.117-148
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• 2022

The full impact of COVID-19 has yet to be felt: while it may not define the new decade, it is clear that its immediate significance was to test many of the basic operating assumptions and procedures of global civilization. Even as vaccines are developed and utilized and even as it is possible to see the beginning of the end of COVID-19 as a discrete historical event, it remains unclear as to its ultimate importance. That said, it is evident that the academic exploration of Southeast Asia will also be affected by both the global and regional experiences of the pandemic. "Breakthroughs of Area Studies and ASEAN in the Era of Homo Untact" promises to help reconceptualize the study of the region by highlighting the importance of redefined spatial relationships and new potentially depersonalized modes of communication. This paper acknowledges these issues by suggesting that the transformations caused by the pandemic should motivate scholars to raise new questions about how to understand humanity-particularly as it is defined by societies, nations and regions. Given that COVID-19 (and the response to it) has altered many of the fundamental rhythms of globalized regions, there is sufficient warrant for re-examining both the ways in which disease, health and their related spaces affect the perceptions of Southeast Asia. To achieve "breakthroughs" into the investigation of the region, it makes sense to have another glance at the ways in which the discourses about diseases and health may have helped to inscribe definitions of Southeast Asia-or, at the very least, the nations, societies and peoples who live within it. In order to at least consider these larger issues, the discussion will concentrate on a formative moment in the conceptualization of Southeast Asia-British engagement with the region in the late 18^th and early 19^th centuries. To that end three themes will be highlighted: (1) the role that British diplomatic and military narratives played in establishing the information priorities required for the construction of colonial knowledge; (2) the importance not only of "colonial knowledge" but information making in its own right; (3) in anticipation of the use of big data, the manner in which manufactured information (related to space and disease) could function in shaping early British perceptions of Southeast Asia-particularly in Batavia and Java. This discussion will suggest that rather than see social distancing or increased communication as the greatest outcome of COVID-19, instead it will be the use of data-that is, big, aggregated biometric data which have not only shaped responses to the pandemic, but remain likely to produce the reconceptualization of both information and knowledge about the region in a way that will be at least as great as that which took place to meet the needs of the "New Imperialism." Furthermore, the definition and articulation of Southeast Asia has often reflected political and security considerations. Yet, the experience of COVID-19 could prove that data and security are now fused into a set of interests critical to policy-makers. Given that the pandemic should accelerate many existing trends, it might be foreseen these developments will herald the triumph of homo indicina: an epistemic condition whereby the human subject has become a kind of index for its harvestable data. If so, the "breakthroughs" for those who study Southeast Asia will follow in due course.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.26 no.1
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• pp.47-59
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• 2023

Due to climate change and urbanization, abnormally high temperatures and heat waves are expected to increase in urban and deteriorate thermal comfort. Planting of street trees and changing the albedo of urban surfaces are the strategies for mitigating the thermal environment of urban, and both of these strategies affect the exposure and blocking of radiative fluxes to pedestrians. After measuring the shortwave and longwave radiation according to the ground surface with different albedo and the presence of street trees using the CNR4 net radiometer, this study analyzed the relationship between this two strategies in terms of thermal environment mitigation by calculating the MRT(Mean Radiant Temperature) of each environment. As a result of comparing the difference between the downward shortwave radiation measured under the right tree and at the control, the shortwave radiation blocking effect of the tree increased as the downward shortwave radiation increased. During daytime hours (from 11 am to 3 pm), the MRT difference caused by the albedo difference(The albedo of the surfaces are 0.479 and 0.131, respectively.) on surfaces with no tree is approximately 3.58℃. When tree is present, the MRT difference caused by the albedo difference is approximately 0.49℃. In addition, in the case of the light-colored ground surface with high albedo, the surface temperature was low and the range of temperature change was lower than the surrounding surface with low albedo. This result shows that the urban thermal environment can be midigate through the planting of street trees, and that the ground surface with high albedo can be considered for short pedestrians. These results can be utilized in planning street and open space in urban by choosing surfaces with high albedo along with the shading effect of vegetation, considering the use by various users.

• Journal of the Korean Regional Science Association
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• v.39 no.3
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• pp.3-12
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• 2023

The issue to be discussed is set as the relationship between urban fragmentation and urban heat phenomena. The fragmentation is recognized as a negative form that commonly occurs in the process of urbanization. The purpose of this study is to examine the relationship between urbanization entropy and heat phenomenon by looking at the five major cities in Korea. The employed methods are InVEST Urban Cooling Model and MSPA (Morphological Spatial Pattern Analysis) by using the meteological data for the July 2018. The major results are as follows; First, a low rank correlation(rho=-0.3) is found in the relation between entropy and Cooling Capacity Index (CCi). Second, a very high level of rank correlation is observed between entropy and Average Temperature(℃)(rho=0.9). The implications are that 1) a city with a large degree of sprawling development can have a negative effect on urban heat phenomena; 2) the composition of land use including dispersion and concentration in non-urbanized areas, which has the characteristics of open space, can affect the urban thermal environment. Due to the limited number of case studies, it is appropriate to understand that a possibility, not generalization, is observed between entropy and heat phenomena in urbanized areas.

• Nuclear Engineering and Technology
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• v.25 no.4
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• pp.529-538
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• 1993

A stochastic way using continuous time Markov process is presented to model the one-dimensional nuclide transport in fractured rock matrix as an extended study for previous work ［1］. A nuclide migration model by the continuous time Markov process for single planar fractured rock matrix, which is considered as a transient system where a process by which the nuclide is diffused into the rock matrix from the fracture may be no more time homogeneous, is compared with a conventional deterministic analytical solution. The primary desired quantities from a stochastic model are the expected values and variance of the state variables as a function of time. The time-dependent probability distributions of nuclides are presented for each discretized compartment of the medium given intensities of transition. Since this model is discrete in medium space, parameters which affect nuclide transport could be easily incorporated for such heterogeneous media as the fractured rock matrix and the layered porous media. Even though the model developed in this study was shown to be sensitive to the number of discretized compartment showing numerical dispersion as the number of compartments are decreased, with small compensating of dispersion coefficient, the model agrees well to analytical solution.

• Korean Journal of Cognitive Science
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• v.34 no.1
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• pp.39-66
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• 2023

New media moved the place of social exchange to the Internet, allowing large groups to communicate in one place beyond the limits of time and space. Recent studies have also reported cases in which human social abilities do not keep up with the expansion of group scale through social media. In this context, current study investigated how human perception of social information is affected by the expansion of the group scale in the context of majority bias. Using Internet-based task, the psychological processes that group ratio and group size are perceived and affect majority-biased social information use were investigated, and whether group scale moderates those processes was examined. The group ratio has a positive effect on the majority bias, and the relationship was partially mediated by ratio perception. Group scale did not moderate the relationship between group ratio and ratio perception. On the other hand, the correlation between group size and majority-biased social information use was not significant. Group scale moderates group size perception. The group size and size perception showed positive correlation under the smaller group scale condition. However under the extended group scale condition, the perceived group size became significantly lower and lost its correlation with group size. These results provide evidence that the psychological mechanism related to group size perception was not properly responding to the expansion of the group scale. Furthermore, the possibility of a specific psychological mechanism for processing group size information and the form of information input specifically accepted by majority bias were discussed from perspective of evolutionary psychology.