• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.2
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• pp.77-92
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• 2021

For the construction of a large underground space with a complex plant installed, it is necessary to analyze the stability considering the ground conditions and various load conditions. In this paper, finite element analysis was performed to analyze the support load that can be used in the design of a large underground space for high-density arrangement of complex plant. An analysis of underground continuous wall (D-wall) was performed considering the load and horizontal earth pressure in the large underground space. In addition, foundation ground analysis was carried out according to the load condition of the complex plant. In order to shorten the construction period, increase the space layout utilization, and secure the stability of the plant structure when installing the complex plant underground, the pipe rack module structure analysis was conducted. This study proposes a design and construction method for the optimal arrangement of underground complex plants using the analysis results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.3
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• pp.167-174
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• 2022

This study investigates the behavior of a jointless bridge that integrates superstructure and abutment without an expansion joint. Based on the sensitivity analyses conducted in previous studies, a shell-based model was determined to be the most suitable numerical analysis model for jointless bridges due to the similarity of the model's results compared with the obtained displacement shape, which was influenced by relative errors, precision, and practical aspects. Accordingly, the behavior of a jointless bridge was analyzed at various wall depths using shell element-based and solid element models. In addition, the results of MIDAS Civil and ABAQUS analysis programs were compared. In the case of semi-integrated bridges (A and B), the displacement decreased as the wall depth increased due to the ground reaction force in Case 1 under a linear spring condition and +30℃. In the case where temperature was -30℃, the change in displacement was small because the ground reaction did not occur. As for bridge C (a fully integrated alternating bridge) and bridge D (an integrated chest wall alternating bridge), the displacement decreased as the wall depth increased at both +30 and -30℃ due to pile resistance. As for the comparison between the analysis programs used, the relative error in Case 1 was small, whereas a significant difference in Case 2 was observed. The foregoing variation is possibly due to the difference in the application of the nonlinear spring in the programs.

• Journal of the Korean Geotechnical Society
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• v.39 no.7
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• pp.5-15
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• 2023

The evaluation of passive earth pressure plays a crucial role in the design of earth-retaining structures such as retaining walls and temporary earth-retaining walls to withstand horizontal earth pressure. In the earth pressure theory, active and passive earth pressures represent the earth pressures at the limit state, where the wall displacement reaches the maximum allowed displacement. In the design of earth-retaining structures, the passive earth pressure is considered as the resisting force. In this context, the limit displacement at which passive earth pressure occurs is significantly greater than that associated with the active earth pressure. Therefore, it is irrational to apply this displacement directly to the calculation of passive earth pressure. Instead, it is necessary to consider the mobilized passive earth pressure exerted at the allowable horizontal displacement to evaluate the structural stability. This study proposes an allowable wall displacement, denoted as 0.002 H (where H represents the excavation depth), based on a literature review that focuses on sandy soils. To calculate the mobilized passive earth pressure from the wall displacement, a semi-empirical equation is proposed. By analyzing the obtained data on mobilized passive earth pressure, a reduction factor applicable to Rankine's passive earth pressure is proposed for practical application in sandy soils under different wall movement types.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.2
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• pp.505-513
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• 2014

This paper investigated the effect of joint on the earth pressure against an excavation wall in rockmass with the consideration of various rock and joint conditions. For this purpose, this study briefly reviewed of the previous earth pressure studies, and then numerical parametric studies were conducted based on the Discrete Element Method (DEM) to overcome the limitations of the previous studies. The numerical tests were carried out with the controlled parameters including rock types and joint conditions (joint shear strength, joint inclination angle, and joint set), and the magnitude and distribution characteristics of the induced earth pressure were investigated considering the interactions between the ground and the excavation wall. In addition, the earth pressures induced in rock stratum were compared with Peck's earth pressure for soil ground. The results showed that the earth pressure against an excavation wall in jointed rockmass were highly affected by different rock and joint conditions and thus different from Peck's empirical earth pressure for soil ground.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.141-146
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• 2016

Geotechnial engineering projects that requires excavation activity can cause massive ground deformation and this can damage adjacent structures. Depending on the engineering characteristics of ground material and the excavation depth, the ground movement is various. To overcome this issue, the ground deformation is monitored by multiple sensors. Typically, an inclinometer is installed behind the support wall. In this paper, we present an adaptive duty-cycling control mechanism using wireless sensors for monitoring ground deformation in excavations. The proposed mechanism dynamically adjusts the sleep time based on the urgency degree of sensed data from inclinometer. Through analytical evaluation of expected latency time, we confirm our adaptive duty-cycling mechanism has lower latency compared with periodic duty-cycling mechanism under variable conditions.

• Journal of Soil and Groundwater Environment
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• v.8 no.4
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• pp.12-20
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• 2003

This study presents a mathematical model for simulating the fate and transport of a reactive organic contaminant, TCE, degraded by cometabolism in dual-porosity soils during the installation of in situ biobarrier. To investigate the effect of dual-porosity on transport and biodegradation of organic hydrocarbons, a bimodal approach was incorporated into the model. Modified Monod kinetics and a microcolony concept were employed to represent the effects of biodegrading microbes on the transport and biodegradation of an organic contaminant. The effect of permeability reduction in biobarrier due to biomass accumulation on the flow field were examined in the simulation of a hypothetical field-scale in situ bioaugmentation. Simulation results indicate that the presence of the immobile region can decrease the bioavailability of biodegradable contaminants and that the placement of microbes and nutrients injection wells should be considered for an effective installation of biobarrier during in situ bioaugmentation scheme.

• Journal of the Korean Institute of Gas
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• v.12 no.4
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• pp.14-20
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• 2008

In this numerical study, the leakage safety of the LNG tank in which is constructed by membrane inner tank-plywood-polyurethane form-plywood-prestressed concrete structures has been presented for four leakage analysis models. The LNG leak criterion of the tank wall with a storage capacity of $200,000\;m^3$ is analyzed based on the thermal resistance technique. This means that if the cryogenic temperature of a leaked LNG is detected at the outer side of the PC wall, it may be leaked through the wall thickness of the tank. The calculated results based on the thermal resistance method between two walls show that the plywood, PUF, and another plywood walls may block the leakage of the leaked LNG even though the strength of these walls is already collapsed by a leaked LNG pressure. But, the leaked LNG may pass the thickness of the prestressed concrete wall for a period of elapsed time even though the PC outer tank supports the leaked LNG pressure. Thus, the PC outer tank may extend the leakage time of a leaked LNG.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.3
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• pp.242-248
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• 2017

Recently, Population has been concentrated in cities due to rapid economic growth. As a result, urban buildings are becoming more dense, high-rise, and diversified. The shape of these urban buildings increases the risk of fire, accidents and crime. The narrow living space has the characteristic of the unchanged floor. In case of a fire, the living space of the narrow residence is large in the damage because the smoke diffusion rate is fast. The radio wave transmittance and transmission distance of wireless communication used in fire fighting operations vary depending on the type of building materials and buildings. Therefore, this paper analyzes the building materials and structural characteristics of the narrow residential space for efficient fire fighting operations. We have developed a communication environment solution for a narrow residential space for the optimal fire fighting operation through the measurement of the radio wave transmittance and the transmission distance of the wireless communication.

• Journal of Conservation Science
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• v.30 no.1
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• pp.55-65
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• 2014

On this studyed, the Wibongsa BoGwangMyungJun BaekEuiKwanEum wall-painting was conservation of Scientific research ahead. This study carried out Grain size analysis, SEM-EDS, XRD, P-XRF, FT-IR and ultrasonic exploration for wall-painting. As a result, walls layer used to mineral particles size was mixing the medium-texture and fine texture. painting layers pigments used to base paintings was ocher, white pigments was hobun, red pigments was suckganju, green pigments was suckruk. Also BackuiKannon wall-painting walls damage reason of that was long-term physical shocks. painting layers damage was include detachment or powders. it is affected by temperature and humidity. Therefore in the future conservation of wall-paintings through scientific analysis based on such data, conservation processing is performed through the preservation and enhance the stability of the paintings as a basis for the conservation of management can be utilized.

• The Journal of Engineering Geology
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• v.18 no.3
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• pp.277-285
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• 2008

For the soil nailing, recently, its application is expanded, but there is no officially approved method to design it yet. Furthermore, there are a great number of design valuables in soil nailing, it is also used without clear data under the situation that uncompleted detailed research on the sensibility between design variables. Especially, there has no deal with the installation angle of the nail - the major contents in this study. Therefore, this study based on the theoretical estimation analyzed safety rate about the angle of the nail, unit weight, adhesive force, internal friction angle and tensile farce worked on nail in the case of the rear of pond side is both horizontal and perpendicular. As a result, it could be verified that the safety rate increased on every cases in the situation of the nail installation angle was in upward direction than in downward direction.