• Economic and Environmental Geology
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• v.43 no.2
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• pp.149-162
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• 2010

The most serious problem in oil stockpiles with artificial underground cavern is maintaining the stability of ground water system. In order to understand the ground water system around K-1 site, we determined the regional flow direction and level distribution of groundwater, and investigated the major geologic factors influencing their flow system. Reactivated surface along the contact between granite and gneiss, and fractures and faults along the long acidic dyke may contribute as important pathways for groundwater flow. Within K-1 site, groundwater level fluctuation is closely related to the rainfall events and injection from surface or influx water. In this project, the effect of groundwater pumping from the southern wells was examined. Based on equations relating water level drawdown to pumping rate at those wells, their pumped outflow of groundwater ranged from $80\;m^3$/day to less than $250\;m^3$/day. The modeling results with MODFLOW imply that the previous groundwater pumping at distance of 1.2 km may not affect the groundwater level variations of the K-1 site. However, continuous pumping work at quantity over $250\;m^3$/day in this area will be able to affect the groundwater system of the K-1 site, particularly along the acidic dyke.

• Economic and Environmental Geology
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• v.46 no.6
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• pp.495-508
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• 2013

Recently, stable isotopes (${\delta}^{18}O$ and ${\delta}D$) of water are increasingly analyzed using laser-based technologies. These methods have advantages over Isotope Ratio Mass Spectrometry (IRMS) in that they can be used for in-situ measurements and require much less maintenance and preparation work. Two types of laser-based methods are currently available, which have different analytical principles; OA-ICOS (off-axis integrated cavity output spectroscopy) and WS-CRDS (wavelength-scanned cavity ring-down spectroscopy). In the WS-CRDS instrument, water is vaporized at controlled environment and transferred to an optical cavity by nitrogen carrier gas, and stable isotopic compositions of water vapor are measured using the degree of absorbance of specific wavelengths and the ratios of attenuation time of the laser intensity with the sensitivity of ppb to tens of ppt level. In this study, we introduce the principle of the WS-CRDS technology and the performance results including stability and comparisons with Isotope Ratio Mass Spectrometry (IRMS) and suggest possible applications of various topics in isotope hydrology.

• Journal of Korea Port Economic Association
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• v.32 no.4
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• pp.193-209
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• 2016

The Mekong River is a river in the south-eastern part of the continent of Aisa. It flows through the countries of Thailand, Lao PDR, Cambodia, Myanmar, and Vietnam that are located in Indochina and are members of ASEAN. These countries are growing rapidly and many others have entered into these markets. As the number of manufactures has increased, logistics markets become very attractive to our logistics companies that want to expand their business. This study focuses on four countries, Lao PDR, Cambodia, Myanmar, and Vietnam, which have potential economic growth and shows the environment of logistics with current logistics infrastructure and related investment law and system. The goal of this study to provide, with strength, weakness, opportunities, and threats(SWOT) analysis, some strategies to enter 4 countries' logistics market with SWOT and the strategies are as follows; First, foreign direct investment in logistics is linked with logistics infrastructure projects. Our government should strengthen its role to find cooperation programs that make connect with logistics business. Second, a logistics company is better off in a consortium with other manufacturers or other logistics companies to ensure minimum cargo and reduce entry risks. Finally, the four countries' roles as a logistics bases need to divided according to their environments, to benefits of logistics connecting between India and China.

• Journal of Digital Convergence
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• v.11 no.11
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• pp.107-115
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• 2013

The Old Town of Daejeon has significantly gone down due to population decrease and vacancy of buildings. To resolve these problems, it is necessary to develop revitalization measures with unique features, but it is also important to use historical and cultural resources from a certain point for the regeneration of local community. The Old Town of Daejeon has a number of industrial structures and architectural heritages that give character to the spaces, but most of them are being impoverished without any use although they have universal value. This study examined the standards to evaluate the importance and value of modern industrial heritages as historical resources that contributed to the development of local community and discussed case studies to review the value and use of industrial heritages that laid the foundation of Daejeon's development as a modern city to address the needs for urban regeneration through preservation and use of modern industrial heritages. Also, the limitations of administrative efforts were identified and the solutions were sought to address the needs to gather efforts with local government offices and the private sector. In conclusion, this study suggests an active and open policies to use cultural heritages through the use of modern industrial heritages for the revitalization of local communities based on the study of policies for the communication of urban users and community cultural spaces, preservation of landscapes including industrial heritages, and preservation in connection to social organizations and social companies, and that it is necessary to provide policies followed by efforts, i.e., to arbitrate the owners.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.596-608
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• 2018

As urban infrastructure is aging, the possibility of accidents due to the failures or breakdowns of infrastructure increases. Especially, aging underground infrastructures like sewer pipes, waterworks, and subway have a potential to cause an urban ground sink. Urban ground sink is defined just as a local and erratic collapse occurred by underground cavity due to soil erosion or soil loss, which is separated from a sinkhole in soluble bedrock such as limestone. The conventional measurements such as differential settlement gauge, inclinometer or earth pressure gauge have a shortcoming just to provide point measurements with short coverage. Therefore, these methods are not adequate for monitoring of an erratic subsidence caused by underground cavity due to soil erosion or soil loss which occurring at unspecified time and location. Therefore, an alternative technology is required to detect a change of underground physical condition in real time. In this study, the feasibility of a novel magnetic resonance based monitoring method is investigated through laboratory tests, where the changes of path loss (S21) were measured under various testing conditions: media including air, water, and soil, resonant frequency, impedance, and distances between transmitter (TX) and receiver (RX). Theoretically, the transfer characteristic of magnetic field is known to be independent of the density of the medium. However, the results of the test showed the meaningful differences in the path loss (S21) under the different conditions of medium. And it is found that the reflection coefficient showed the more distinct differences over the testing conditions than the path loss. In particular, input reflection coefficient (S11) is more distinguishable than output reflection coefficient (S22).

• Tunnel and Underground Space
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• v.30 no.6
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• pp.573-590
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• 2020

This study presents the current status of DECOVALEX-2023 project Task G and our research results so far. Task G, named 'Safety ImplicAtions of Fluid Flow, Shear, Thermal and Reaction Processes within Crystalline Rock Fracture NETworks (SAFENET)' aims at developing a numerical method to simulate the fracture creation and propagation, and the coupled thermohydro-mechanical processes in fracture in crystalline rocks. The first research step of Task G is a benchmark simulation, which is designed for research teams to make their modelling codes more robust and verify whether the models can represent an analytical solution for displacements of a single rock fracture. We reproduced the mechanical behavior of rock and embedded single fracture using a three-dimensional grain-based distinct element model for the simulations. In this method, the structure of the rock was represented by an assembly of rigid tetrahedral grains moving independently of each other, and the mechanical interactions at the grains and their contacts were calculated using 3DEC. The simulation results revealed that the stresses induced along the embedded fracture in the model were relatively low compared to those calculated by stress analysis due to stress redistribution and constrained fracture displacements. The fracture normal and shear displacements of the numerical model showed good agreement with the analytical solutions. The numerical model will be enhanced by continuing collaboration and interaction with other research teams of DECOVALEX-2023 Task G and validated using various experiments in a further study.

• Journal of Korean Library and Information Science Society
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• v.53 no.4
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• pp.267-292
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• 2022

This study is a basic study to establish a comprehensive plan for operating the Hanam Library, a regional base library that will be built in Gwangsan-gu, Gwangju Metropolitan City. We investigated opinions about the collection, library program, role and task of a regional base library and the operation of the cooperative shared storage. As a result of the study, the information resources that users prefer are a book form of the literary subject, and preferred library services are the use of information resources and participation in cultural events. Public library librarians answered conducting user-centered services and carrying out a cooperative projects between libraries are important and they recognized cooperative acquisition as a task should be performed first. In addition, opinions about the operation of cooperative shared storage is generally positive. The regional base library managers said that it is important to establish library governance by clarifying the status and role of the library and that as a public library, and to promote information services and cooperation projects for local users. The results of this study can be expected to be the useful basic material for the establishment of the Hanam Library comprehensive operation plan.

• Journal of Family Resource Management and Policy Review
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• v.28 no.2
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• pp.11-25
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• 2024

The purpose of this study is to compare the child care time, as well as the perceptions of and satisfaction with the time use, of fathers and mothers in dual-income families with preschool children. 444 time use data were gathered from the Statistics Korea Life Time Surveys in 2019. The results of this study are as follows. First, the total child care time of the two parents per family on a working day was 72.1 min on average, and more time was spent on primary care than on developmental care. Second, the father's child care time on a working day was 40.8 min on average, and the mother's time, almost three times more-110.3 min, which show a significant difference. By type of care, the mother's care time was about three times more than that of father for primary care, and about two times more for developmental care. Third, the mother's primary care time differed by household income level, and the primary care time of both fathers and mothers differed according to the number of their working hours weekly. Fourth, both fathers and mothers felt somewhat tired and had a time deficit, but mothers were less satisfied than fathers with the division of household tasks between them. To encourage fathers' voluntary participation in child care, they must be informed of their joint responsibility with their spouse as parents must be emphasized under the term "co-parenting." It is necessary to expand systems that support parental care and promote a family-friendly culture in workplaces to guarantee the rights of parents.

• Economic and Environmental Geology
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• v.55 no.5
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• pp.511-519
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• 2022

In order to develop an air-stripping based remediation process to remove the TOC (Total Organic Carbon) in groundwater around the underground LPG storage cavern, the laboratory scale experiments at various conditions (change of air injection volume and temperature, the application of ultrasonic treatment, etc.) for two types of groundwater (initial TOC concentration of 608 mg/L and 153 mg/L, respectively). From results of experiment, as the air injection rate for stripping into groundwater increased from 2 L/min to 11 L/min and as the air-stripping time increased from 1 hour to 24 hour, the TOC removal efficiency of air-stripping increased. However, the TOC concentration of treated groundwater was higher than the discharge tolerance limit (100 mg/L) even after 24 hour stripping at the maximum air injection rate of 11 L/min. The main compounds of the TOC in groundwater were identified as methanol and propane and the long stripping time (more than 24 hour) was needed to separate the methanol from groundwater because of the affinity between water and methanol. At 20℃ and 4 L/min of air injection, the TOC removal efficiency increased to 59.1% after 24 hour air-stripping. When the temperature of groundwater increased to 30℃ and 40℃, the TOC removal efficiency increased up to 80.0% and 82.8%, suggesting that more than 24 hour air-stripping at 40℃ is needed to lower the TOC concentration to below 100 mg/L and the additional TOC removal process as well as the air-stripping is necessary. When the temperature increased to 60℃ and the ultrasonic treatment was conjugated with the air-stripping, the TOC removal efficiency increased to 87.8% within 5 hour stripping and the final TOC concentration (72.4 mg/L) was satisfied with the TOC discharge tolerance limit. The TOC removal efficiency for groundwater having low TOC concentration (153 mg/L) also showed similar removal efficiency of 89.7% (the final TOC concentration: 18.9 mg/L). Results in this study supported that the air-stripping conjugated with the ultrasonic treatment could remove successfully the TOC in groundwater around the underground LPG strorage cavern.

• Korean Journal of Construction Engineering and Management
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• v.15 no.1
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• pp.87-100
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• 2014

Environmental problems and the shortage of natural resources are currently gathering more attention in Korea and international countries. With these problems, it is reported that most current domestic buildings are emitting approximately 138 million tons of greenhouse gas. According to a recent report from the investigation of Korean housing population, the total number of households is approximately 12.9 millions, and the apartments that were built more than 15 years ago amounted to 3.1 millions. This shows that the rates of old apartment housings are increasing. Therefore, it is necessary to consider the deteriorated facilities and environmental improvement. Also, the construction industry is benefited by improving these housings which may need either remodeling or reconstruction. Environmental friendly buildings are a rising consideration for remodeling and reconstruction projects; it helps to determine many business matters in construction. The main purpose of this research is to improve environmental condition in apartments with comparison analysis between remodeling and reconstruction alternatives. This research is focused on characteristics of remodeling and reconstruction and it sets up the same condition with each level in order to evaluate the value of environmental friendliness and analyze its definition. The result of this research provides a unique emitting rate at a novel framework and this will cause the reduction of $CO_2$. It is analyzed that the remodeling construction can reduce the great amount of $CO_2$. Therefore, it will be a good decision guideline in selecting the most eco-friendly alternative to improve environment for building construction. Although reconstruction is a popular alternative nowadays in Korea, this research can provide a reason why decision makers should put more emphasis on remodeling as an environment-friendly alternative.