• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.495-512
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• 2022

Due to the concentration of population in the city center, the aboveground structures are saturated, and the development of underground structures becomes important. In addition, it is necessary to apply the reinforcement construction method for the pillar part of the adjacent tunnel that can secure stability, economy, and workability to the site. In this study, the tunnel pillar reinforcement method using prestress and grouting was reviewed. There are various reinforcement methods that can compensate for the problems of the side tunnel, but as the tunnel pillar construction method using prestress and grouting is judged to be excellent in field applicability, stability, and economic feasibility, it is necessary to review the theoretical and numerical analysis of the actual behavior mechanism. Therefore, a scaled-down model experiment was conducted. The reduced model experiment was divided into PC stranded wire + steel pipe reinforcement grouting + prestress (Case 1), PC strand + steel pipe reinforcement grouting (Case 2), and no reinforcement (Case 3), and the displacement of the pillar and the earth pressure applied to the wall were measured. Through experiments, it was confirmed that the PC stranded wire + steel pipe reinforcement grouting + prestress method is the most excellent reinforcement method among various construction methods. It was judged that it could be derived.

• Journal of Family Resource Management and Policy Review
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• v.25 no.2
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• pp.13-24
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• 2021

The purpose of this study was to prepare basic data to set the support direction for low-income households in a socioeconomic crisis situation. The study examined the effect of socioeconomic deprivation experience on the longitudinal changes in family conflict and family relationship satisfaction of low-income households. Using five-year data from the 10th to 14th sessions of the Korean Welfare Panel, we examined the longitudinal changes in family conflict and family relationship satisfaction, and the effect of socioeconomic deprivation experience from the reponses of 803 low-income households. We found that the family conflict of low-income households decreased to a weak level with the change of time, and the rate of change in family relationship satisfaction was not meaningful. In the case of families who experienced early socioeconomic deprivation, their initial value of family conflict was higher than that of inexperienced households, and the rate of change was not significant. The results of this study show that when low-income households experience socioeconomic deprivation, they feel psychological pressure and an increase in family anxiety, resulting in high family conflict and low family relationship satisfaction. On the basis of the study results, we recommend extending economic and social assistance to low-income households in the current socioeconomic crisis. The state is also encouraged to help families manage conflicts on their own and resolve problems.

• Korea and Global Affairs
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• v.3 no.1
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• pp.39-76
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• 2019

This paper is to analyze the trend and implications of the publication of China's defense and security white papers. To this end the paper is composed of 5 chapters titled instruction; publication details and composition of China's defense and security white paper; the gist of the white paper on national defense and security during the Chinese president Xi Jinping era; the implications of Chinese white paper on national defense and security during the Chinese president Xi Jinping era; and conclusion. The Chinese Ministry of National Defense had published seven books every two years since 1998 to 2010. In 1995, the ministry published a white paper titled 'China's arms control and disarmament' for the first time. In 2013, it published a white paper titled 'The Diversified Employment of China's Armed Forces' and 'China's Military Strategy' in 2015. All have the common characteristic of being a propaganda policy reflecting China's strategic calculations. It seems that China has began to publish defense white papers in a proactive manner, due to the following factors: (1)pressure on China to demand military transparency from neighboring countries such as the United States; (2)the erosion of the 'China threat.' and (3)confidence in the achievement of China's military modernization. The 'active defensive strategy' and the 'strong defense strategy' of Si Jinping are implied in the words "China's dream is a dream of a powerful country and dream of a strong nation is essential to construct a strong nation." His these strategies have raised security concerns for neighboring countries. We need to maintain and reinforce strong ROK-US security cooperation, and hedging strategies to harmoniously promote ROK-China economic cooperation.

• Journal of the Korean Institute of Gas
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• v.23 no.1
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• pp.27-35
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• 2019

In order to solve the global warming and reduce greenhouse gas emissions, $CO_2$ capture technology was developed by applying oxy-fuel combustion. But there has been such a problem that its economic efficiency is low due to the high price of oxygen gases. ASU is known to be most suitable method to produce large quantity of oxygen, to reduce the oxygen production cost, the efficiency of ASU need to be improved. To improve the efficiency of ASU, exergy analysis can be used. The exergy analysis provides the information of used energy in the process, the location and size of exergy destruction. In this study, the exergy analysis was used for process developing and optimization of large scale ASU. The process simulation of ASU was conducted, the results were used to calculate the exergy. As a result, to reduce the exergy loss in the cold box of ASU, a lower operating pressure process was suggested. It was confirmed the importance of heat leak and heat loss reduction of cold box. Also, the unit process of ASU which requires thermal integration was confirmed.

• Journal of Digital Convergence
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• v.18 no.12
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• pp.279-284
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• 2020

In January 2020, COVID19 plunged the whole planet into a pandemic. This has caused great economic losses and is causing social confusion. COVID19 has a superior infection rate among people with underlying disease such as heart disease, high blood pressure, diabetes, stroke, depression, and cancer. In addition, it was studied that patients with underlying disease had a higher fatality rate than those without underlying disease. In this study, the presence or absence of underlying disease was classified using EEG data. The data used to classify the presence or absence of underlying disease was EEG data provided by Data Science lab, consisting of 33 features and 69 samples. Z-score was used for data pretreatment. Classification was performed using the neural network NEWFM and ZNN engine. As a result of the classification of the presence or absence of the underlying disease, the experimental results were 77.945 for NEWFM and 76.4% for ZNN. Through this study, it is expected that EEG data can be measured, the presence or absence of an underlying disease is classified, and those with a high infection rate can be prevented from COVID19. Based on this, there is a need for research that can subdivide underlying disease in the future and research on the effects of each underlying disease on infectious disease.

• Maritime Security
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• v.2 no.1
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• pp.71-123
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• 2021

Seoul is under increasing pressure to choose between the US-led IndoPacific Strategy (IPS) and China's Belt and Road Initiative (BRI). Accordingly, this paper undertakes a detailed appraisal of the IPS and the BRI in the context of Korea's national policy imperatives. Based on a study of network structure by Daniel Nexon and Thomas Wright (2007), the present study seeks to identify a particular network structure within the IPS and the BRI. Through this analysis, the relationship between the core and the participant states will be addressed. Awareness of specific configurations of the IPS and the BRI is important as these reveal what participant states can expect from each network. According to Nexon and Wright, there are four types of network structure: unipolar anarchy, hegemonic order, constitutional order, and imperial order. Based on this, we argue that the IPS has a constitutional order and the BRI has an imperial order. Therefore, we suggest to Seoul that participating in the IPS may make more room for an independent foreign policy than would a BRI partnership with China. South Korea would benefit by participating in the IPS in terms of its national security, striking a favourable regional balance of power.

• Tunnel and Underground Space
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• v.32 no.2
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• pp.160-172
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• 2022

The design regulations for simple explosive storage in Korea only stipulate standards for the materials and thickness of the wall of the structure because the amount of explosives that can be stored is small. There is concern about secondary damage during an internal explosion in a simple storage facility, and it is necessary to reexamine the current standards. The numerical analysis for the TNT 15 kg explosion inside the simple storage was carried out by setting the factors using the robust experimental design method. The displacement of the structure generated under the same time condition was analyzed, and the contribution was evaluated. The contribution of concrete thickness was the highest, and the contribution of concrete strength and rebar arrangement was lower than that of concrete thickness. The reinforcement diameter contributed extremely little to the displacement. The structural standards of the simple storage that are currently applied are insufficient on blast resistance, and it is necessary to present new design standards. Therefore, the design factor to be applied later analysis and actual experiments were taken into consideration. For the design variables, the thickness of the concrete was 15 cm considering the displacement, the concrete strength was selected as general concrete considering the inlet discharge pressure, the factor with the lowest average displacement was selected for the reinforcement arrangement and the diameter of the reinforcement, the factor with the smallest level was selected in consideration of economic feasibility because the difference in displacement was low.

• Journal of the Korean GEO-environmental Society
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• v.23 no.6
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• pp.5-17
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• 2022

The performance of the relief wells installed for the purpose of controlling seepage of the dam embankment is affected by various parameters such as diameter, spacing, penetration rate, permeability coefficient of the ground, thickness of the foundation layer. Therefore, when the relief wells are adopted for the purpose of reducing seepage pressure, these parameters should be sufficiently reviewed to determine the installation specifications of the relief wells. This study evaluated the effect of the length of the geosynthetics blanket on the performance of the relief wells installed in the downstream part of the dam embankment with blankets in the upstream and downstream part of the dam embankment as countermeasure methods to control seepage of the dam embankment. In the relationship between the length of the upstream and downstream blanket and the discharge, the discharge of the relief wells decreases as the length of the upstream blanket increases, and on the other hand, the discharge of the relief wells decreases as the length of the downstream blanket increases. In the upper and lower blanket length-spacing relationship, as the length of the upstream blanket increases, the spacing of the relief wells increases and as the length of the downstream blanket increases, the spacing of the relief wells decreases. Therefore, when installing the relief wells in parallel with the blanket, it was found that increasing the length of the upstream blanket is more efficient than increasing the length of the downstream blanket in order to minimize the discharge of seepage discharge and to ensure economic feasibility by wider installation of the relief wells.

• Journal of the Korean Institute of Gas
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• v.26 no.5
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• pp.1-9
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• 2022

Selection of a suitable artificial lift is important in terms of efficient operation and economics for oil production. In general, process of well design includes the selection of artificial lift, but the oil recovery could be enhanced by use of hybrid system combined with two types of artificial lift method according to reservoir condition for oil production. Electric submersible pump (ESP), as a presentative artificial lift method, is a manner for supplying the pressure in the lower part of oil well by using of a multi-stage centrifugal pump with an electric energy. However, there is a disadvantage that has a limit to the application period because of mechanical defection on ESP. Accordingly, it is possible to reduce the shutdown time of production well by applying the ESP/Gas lift hybrid system, which is to switch to a gas lift when an ESP is defective. This study describes the effect of ESP/gas lift hybrid system compared with ESP method for a onshore horizontal well locating in the of Permian basin, USA. As a result of study, ESP/gas lift hybrid system could make more effective productivity than ESP method. Also, we quantitatively predicted how much economic benefit would be obtained when the hybrid system was applied in the production well.

• Journal of Korea Water Resources Association
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• v.56 no.9
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• pp.587-602
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• 2023

Due to climate change, population growth, and economic development, the demand for water in the urban water system (UWS) and the energy required for water use constantly increase. Therefore, beyond the traditional method of considering only the water sector, the Nexus approach, which considers synergies and trade-offs between the water and energy sectors, has begun to draw attention. In previous researches, the Nexus methodology was used to demonstrate that the UWS is an energy-intensive system, analyze the water-energy efficiency relationship surrogated by energy intensity, and identify climate (long-term climate change, drought, type), geographic characteristics (topography, flat ratio, location), system characteristics (total supply water amount, population density, pipeline length), and operational management level (water network pressure, leakage rate, water saving) effects on the UWS. Through this, it was possible to suggest the direction of policies and institutions to UWS managers. However, there was a limit to establishing and implementing specific action plans. This study built the energy intensity matrix of the UWS, quantified the impact of city conditions, external influences, and operational management levels on the UWS using the water-energy Nexus model, and introduced water-energy efficiency criteria. With this, UWS managers will be able to derive strategies and action plans for efficient operation management of the UWS and evaluate suitability and validity after implementation.