• Journal of the Korean Institute of Gas
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• v.26 no.4
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• pp.9-17
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• 2022

This paper is the continuation of our previous paper, which we refer to as numerical analysis of phase behavior and flow properties in an injection tubing during gas phase CO₂ injection. Our study in this paper show the results during supercritcal CO₂ injection under the same project. Geological CO₂ storage technology is one of the most effective method to decrease climate change due to high injectivity and storage capacity and economics. A demonstration-scale CO₂ storage project was performed in a deep aquifer in the Pohang basin, Korea for a technological development in a large-scale CO₂ storage project. A problem to consider in the early stage design of the project was to analyze CO₂ phase change and flow characteristics during CO₂ injection. To solve this problem, injection conditions were decided by calculating injection rate, pressure, temperature, and thermodynamic properties. For this research, we simulated and numerically analyzed CO₂ phase change from liquid to supercritical phase and flow characteristics in injection tubing using OLGA program. Our results provide discharge pressure and temperature conditions of CO₂ injection combined with a pressure of an aquifer.

• Journal of International Area Studies (JIAS)
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• v.16 no.2
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• pp.121-146
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• 2012

The purpose of this paper is to study on China's emergence and its influence on international society against the U.S. hegemony. Recently, China's influence has proliferated in Central Asia as well as East Asia at a rapid rate. China, through its soft balancing strategy, increased its influence in Central Asia in response to the U.S. power and behavior. This study analyzes the relationship among China and Central Asia with the view of soft balancing theory. In order to determine whether China's strategy on Central Asia is soft balancing, this paper presents three indicators: 1) Second-tier major power is willing to take a strategy that increase diplomatic cost of hegemony or counter the hegemony influence through using regional and global multilateral cooperation. 2) Second-tier major power is willing to not only increase its influence by strengthening regional economic cooperation, but also check the extension of the hegemony economic influence into its boundary. 3) Second-tier major power intends to prevent expanding hegemony military influence into the region through limited military cooperation and increasing military spending, and denying territory. This paper analyze China's multi-polar strategy, economic and energy cooperation with Central Asia countries, and the military and security cooperation with multilateral organizations such as SCO.

• Journal of the Korean Geotechnical Society
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• v.22 no.9
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• pp.45-59
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• 2006

The successful performance of any numerical geotechnical simulation depends on the accuracy and efficiency of the numerical implementation of constitutive model used to simulate the stress-strain (constitutive) response of the soil. The corner stone of the numerical implementation of constitutive models is the numerical integration of the incremental form of soil-plasticity constitutive equations over a discrete sequence of time steps. In this paper a well known two-surface soil plasticity model is implemented using a generalized implicit return mapping algorithm to arbitrary convex yield surfaces referred to as the Closest-Point-Projection method (CPPM). The two-surface model describes the nonlinear behavior of coarse-grained materials by incorporating a bounding surface concept together with isotropic and kinematic hardening as well as fabric formulation to account for the effect of fabric formation on the unloading response. In the course of investigating the performance of the CPPM integration method, it is proven that the algorithm is an accurate, robust, and efficient integration technique useful in finite element contexts. It is also shown that the algorithm produces a consistent tangent operator $\frac{d\sigma}{d\varepsilon}$ during the iterative process with quadratic convergence rate of the global iteration process.

• Journal of Digital Convergence
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• v.20 no.3
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• pp.459-468
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• 2022

The outbreak of COVID-19 is facing a global crisis. Therefore, this study comprehensively reviews the risk perception, tourism attitude, and tourism intention of potential tourists in the COVID-19 situation. As a research finding, three factors were derived for tourism risk perception: physical risk, social risk, and performance risk. It is verified that social risk to be a significant factors affecting tourism attitude. Also, it proved that social risk, performance risk to be important factors affecting tourism intention. A t-test was conducted to examine the implications of demographic characteristics(gender, age, job) in the study. As a result of the analysis, it was found that potential tourists in their 20's age perceived social risk as more important than other age groups. In addition, potential tourists in their 20's showed more positive tourism attitudes than other age groups. As a result of analyzing differences according to job, it was found that the student group had higher social risk, tourism attitude, and tourism intention than other occupational groups. Based on the research results, it can help derive strategies to reduce tourists' perception of risk in special situations such as COVID-19 and contribute to academia.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.3
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• pp.155-163
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• 2023

Real-time monitoring technology is critical for ensuring the safety and reliability of nuclear power plant structures. However, the current seismic monitoring system has limited system identification capabilities such as modal parameter estimation. To obtain global behavior data and dynamic characteristics, multiple sensors must be optimally placed. Although several studies on optimal sensor placement have been conducted, they have primarily focused on civil and mechanical structures. Nuclear power plant structures require robust signals, even at low signal-to-noise ratios, and the robustness of each mode must be assessed separately. This is because the mode contributions of nuclear power plant containment buildings are concentrated in low-order modes. Therefore, this study proposes an optimal sensor placement methodology that can evaluate robustness against noise and the effects of each mode. Indicators, such as auto modal assurance criterion (MAC), cross MAC, and mode shape distribution by node were analyzed, and the suitability of the methodology was verified through numerical analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4C
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• pp.205-212
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• 2008

In this research, the effect of rock mass weathering on the side shear resistance of drilled shaft socketed into igneous-metamorphic rock was investigated. For that, 23 cast-in-place concrete piles with diameters varying from 400mm to 1,500mm were constructed at four different sites, and the static axial load tests were performed to examine the resistant behavior of the piles. A comprehensive field/laboratory testing program at the field test site was also performed to describe the in situ rock mass conditions quantitatively. The side shear resistance of rock socketed piles was found to have no intimate correlation with the compressive strength of the intact rock. However, the global rock mass strength, which was calculated by the Hoek and Brown criteria, was found to closely correlate to the side shear resistance. The ground investigation data regarding the rock mass conditions (e.g. $E_m$, $E_{ur}$, $p_{lm}$, RMR, RQD, j) were also found to be highly correlated with the side shear resistance, showing the coefficients of correlation greater than 0.75 in most cases. Additionally, the applicability of existing methods for the side shear resistance of weathered granite-gneiss was verified by comparison with the field test data. The existing methods which consider the effect of rock mass condition were modified and/or extended for weathered rock mass where mass factor j is lower than 0.15, and RQD is below 50%.

• The Journal of the Convergence on Culture Technology
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• v.9 no.2
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• pp.437-444
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• 2023

With the development of modern society, society provides people with a quick and convenient life, but it also causes anxiety, depression, other psychological and mental illnesses, so art can also be used as a way and path to treating psychological disorders. Art therapy is a creative method of delivery used in therapy, resulting from the fusion of art and psychotherapy. Art is a service and public art activity, mainly aimed at solving human psychological problems, providing nonverbal expression and communication opportunities, and treating psychological and psychological entanglement by improving emotion, stability, and indirectly inappropriate behavior through multi-disciplinary convergence. Art therapy, as an independent discipline, began in Europe in the 3rd and 40th centuries and was mainly influenced by two psychologists, Sigmund Freud and Carl (Gustav Jung). We Starting with the theoretical foundation of psychoanalysis, this paper explores the effectiveness of modern people's psychotherapy, analyzes the similarities between the two ideas, explores the application of art therapy and the development of science and technology, and provides the public with various ways of art therapy and the validity of science and technology.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5A
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• pp.699-707
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• 2008

For most structural evaluation of bridge integrity, it is very important to measure the geometric profile, which is a major factor representing the global behavior of civil structures, especially bridges. In the past, because of the lack of appropriate methods to measure the deflection profile of bridges on site, the measurement of deflection has been restricted to just a few discrete points along the bridge, and the measuring points have been limited to the locations installed with displacement transducers. Thus, some methods for predicting the static deflection by using fiber optic strain sensors has been applied to simply supported bridges. In this study, a method of estimating the static deflection profile by using strains measured from suspension bridges was proposed. Based on the classical deflection theory of suspension bridges, an equation of deflection profile was derived and applied to obtain the actual deflection profile on Namhae suspension bridge. Field load tests were carried out to measure strains from FBG strain sensors attached inside the stiffening girder of the bridge. The predicted deflection profiles were compared with both precise surveying data and numerical analysis results. Thus, it is found that the equation of predicting the deflection profiles proposed in this study could be applicable to suspension bridges and the FBG strain sensors could be reliable on acquiring the strain data from bridges on site.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.372-379
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• 2023

International oil prices are expected to increase from $85 a barrel this year to up to $100 a barrel in the second half of the year; this is likely to increase orders for offshore plants in the global market. One main characteristic of offshore plants is that a large helideck is located on the top side, and aluminum alloys are used as the basic material of the structure for weight reduction and corrosion resistance. Shipowners are increasing the size of helicopters to quickly evacuate lives in the event of an emergency, and the safety use load of devices that can stably secure helicopters to the deck is also required to increase. Owing to the nature of the aluminum material, the structural strength caused by welding is greatly reduced; therefore, the fixing device must be designed by embedding it in the deck and fixing it with bolts. In this study, a model applying aluminum alloy 6082-T6 was developed to develop a helicopter fastening device that can be used for large helidecks (diameter = 28 m). The developed item was verified through nonlinear structural strength calculation to satisfy the load used for the actual fastening condition. The load condition with a 45° showed a lower ultimate strength than the 90° case owing to local plastic collapse. The nonlinear structural collapse behavior showed a result similar to that of the experimental test. The main contents derived from this study are considered to be reference materials when evaluating the structural strength of similar aluminum equipment.

• Anxiety and mood
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• v.19 no.2
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• pp.77-82
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• 2023

Objective : During the coronavirus disease 2019 (COVID-19) pandemic, hospital avoidance had a significant impact on public health. We investigated the factors associated with hospital avoidance and explored practical strategies hospitals could employ to address this phenomenon. Methods : We conducted a patient experience survey in a general hospital in Korea during the COVID-19 pandemic. Between July 6, 2020, and July 20, 2020, a total of 842 patients who had previously visited hospitals before the COVID-19 outbreak participated. Self-reported hospital avoidance, factors associated with hospital avoidance, and satisfaction with the hospital's infection control policies were the main outcomes. Binary logistic regression analysis was used to identify associated factors. Results : Data indicated that 29.9% (n=252) of the respondents avoided visiting the hospital after the COVID-19 outbreak. Satisfaction with the hospital infection control policy (odds ratio [OR]=2.297, p<0.001), female sex (OR=1.619, p<0.05), and higher educational level (OR=1.884, p<0.001) were associated with hospital avoidance. The "entrance body temperature check" was the most satisfactory policy among the hospital's infection control policies. Conclusion : To manage hospital avoidance during an infectious disease crisis, targeted policies for at-risk groups and hospital policies to reassure and satisfy patients are needed.