• Journal of the Korean Geosynthetics Society
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• v.18 no.2
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• pp.45-54
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• 2019

This paper describes the results of finite element analysis (FEA), in order to investigate a characteristics of pile pullout behavior according to the conditions of the relative density and fines content in original ground. In the FEA, a boundary elements and strength reduction factors ($R_{inter}$) on pile-soil interface were applied to simulate appropriately the shear behavior at the pile-soil interface, and then the reliability of numerical analysis method was verified by comparison of FEA results and previous experimental research(You et al., 2018). In addition, a the deformation characteristics at the pile-soil interface and determination method of $R_{inter}$ value was laid out. The results showed that the FEA, based on the analytical model applied in this study simulates appropriately the characteristics of the pile-soil interface by pullout model test of pile. In order to apply the suggested $R_{inter}$ value, it is necessary to consider the condition of the relative density and the fines content in ground.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.2
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• pp.50-53
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• 2019

In this study, polycrystalline silicon thin film useful for the solar cells was fabricated by AIC(Aluminum Induced Crystallization) process. A diffusing barrier for this process is prepared with $Al_2O_3$. For the maximization of the grain size of the polycrystalline silicon, a selective blasting of the $Al_2O_3$ diffusing barrier was conducted before annealing treatment. The heat treatment for the activation of the amorphous-Si (a-Si) layer was carried out with Rapid Thermal Annealing (RTA) process. Crystallization of the a-Si layer was analyzed with XRD. It was confirmed that a-Si was crystallized at $500^{\circ}C$ and the silicon crystal is observed to be formed and the grain size of the polycrystalline silicon was observed to be $15.9{\mu}m$.

• Journal of the Korean Geosynthetics Society
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• v.18 no.3
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• pp.1-9
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• 2019

In this study, the effect of ground improvement was to be verified by granular compaction pile from the ground reclaimed with Fly Ash landfill site. The depth and strength parameters of the Fly ash layer was determined using the ground investigation and cone penetration test. And the STONE C program was used to predict the strength parameter, bearing capacity and settlement of the improved ground. As a result of the plate bearing test, the bearing capacity of improvement ground was higher than the design load and the settlement was smaller than the reference value. After the construction, the improvement effect by the cone penetration test was confirmed. The cone penetration resistance value($q_c$) increased by 250% to 500% and the effect was excellent.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.6
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• pp.237-243
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• 2020

In this study, a silane-based coating was applied to improve corrosion resistance and thermal efficiency performance of a brazed plate heat exchanger (BPHE) composed of stainless plate and copper (Cu) brazing. Although the selected coating material was applied to the BPHE by evaluating the corrosion and contact angle according to the coating material, the result of the heat transfer performance evaluation showed that the thermal efficiency was lower than that of the uncoated BPHE. It was analyzed that the adhesion of the coating agent to the flow path inside the BPHE and the residual coating agent on the surface acted as heat resistance, preventing heat transfer. This is due to the structural characteristics of the BPHE in which a fine flow path exists inside, and it is believed that manufacturing after coating the surface of the flow path in advance in the manufacturing process of the BPHE can improve heat transfer performance.

• Journal of the Korean Geosynthetics Society
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• v.20 no.2
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• pp.35-43
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• 2021

In this paper, the sub-structuring technique-applied train-bridge interaction analysis model, which is formulated based on the simplified three-dimensional train-bridge interaction analysis model for high-speed bridge-train interaction analysis, is presented. In the sub-structuring technique, the super-structure and the supporting structure of railway bridges can be modeled as sub-structures, and train-bridge interaction analysis can be efficiently performed. As a train analysis model, two-dimensional train model is used, and the Lagrange equation of motion is applied to derive the equation of motion of two-dimensional train. In the sub-structuring technique, the number of degrees of freedom can be reduced by using the condensation method, thus reducing the time and cost for calculating the eigenvalues and eigenvectors, and the time and cost for the subsequent calculation. In this paper, Guyan reduction method is used as sub-structuring technique. By combining simplified three-dimensional bridge-train interaction analysis and Guyan reduction method, the efficient and accurate bridge-train interaction analysis can be performed.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.1
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• pp.43-47
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• 2022

In this study, we demonstrated an eco-friendly thin-metallic-film-based heater which can be operated in water. Based on the materials stability, Mo was selected as the heating element to secure long-term stability. Using a magnetron sputtering, 40 nm-thick Mo layers were deposited onto a glass substrate, followed by the deposition of 60-nm-thick ZnO layer to prevent oxidation during the heater fabrication process. Then, PVB (Polyvinyl Butyral) was applied on top of ZnO layer and an additional glass substrate was placed, which were heated at 150℃ for 2 hr. The PVB was cured with strong adhesion by the processing condition. We operated the Glass/Mo/ZnO/Glass heater in water, and it was shown that the water temperature reached 50℃ within 2 minutes, with a minimal resistance change of the heater. Finally, the heaters exhibit a semi-transparency, and this aesthetic advantage is expected to contribute to the added value of the heater.

• Journal of the Korean Geosynthetics Society
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• v.20 no.4
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• pp.33-41
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• 2021

Feldspar, along with Quartz, are the most frequently produced minerals in Korea; however, the potential value is estimated to be significantly low because of the scarce research on the development and application of material properties, except for their limited use in manufacturing minerals, glass, and paints. In this study, we analyzed the eco-friendly material and reactivity improvement characteristics of weathered feldspar through activation technique. The joint structural features observed on the surface of the weathered feldspar show that the joint arrangements are irregularly distributed, and the cavities are interconnected. Due to the irregularly connected cavities on the surface of weathered feldspar, the reaction area of the weathered feldspar is increased; hence the weathered feldspar is considered as a highly reactive pozzolan material when combined with cement. As a result of applying the thermal, mechanical, and chemical activation techniques to improve the functionality of the weathered feldspar, the cation exchange capacity, density, and uniaxial compression strength characteristics were improved. It is considered that weathered feldspar by these porous characteristics can be used as an eco-friendly construction material with excellent physical and chemical properties.

• Journal of the Korean Geosynthetics Society
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• v.21 no.3
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• pp.71-78
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• 2022

In this study, the applicability of underground displacement sensors was considered through rock blasting tests to develop a relatively inexpensive and efficient slope failure prediction system that can quickly detect the risk of slope failure in advance and issue predictions and warnings with accurate judgment. In the blasting experiment, the sensor located close to the blasting source showed a large displacement due to crushing inside the rock and the sensor located away from the blasting source showed a relatively small strain. This study confirmed that the wired and wireless type underground displacement sensor system can be applied to measure the behavior of the rock slope, and it can be used as a basic data for establishing an early warning system to predict slope failure.

• Journal of the Korean Geosynthetics Society
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• v.22 no.3
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• pp.71-86
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• 2023

Rock blasting tests using underground penetration-type displacement sensors were conducted, and three-dimensional finite element numerical analyses were performed to assess their applicability and mitigate slope hazards during rock blasting. Additionally, parameters influencing vibration velocity were investigated during the tests. The results confirmed that underground penetration-type displacement sensors are suitable for monitoring rock slope behavior, and the numerical analyses revealed that the most influential parameter on vibration velocity during rock blasting is the unit weight. Furthermore, it was observed that vibration velocity decreases significantly with distance from the blast source, and proximity to the source leads to substantial variations in vibration velocity due to differences in elastic modulus and unit weight. Changes in internal friction angle and adhesive strength had minimal impact.

• Journal of the Korean Geosynthetics Society
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• v.22 no.1
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• pp.1-7
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• 2023

This study has utilized self-assembled monolayers technology to improve electrical property of graphene-oxide, which has been seperated graphine powder through a chemical exfoliation. Aluminum sulfate (Al₂(SO₄)₃) was applied on graphene-oxide as a reactant, and the fundamental research was carried out to apply on the self-sensing of cement-based construction structures. Electric resistance measurement result has shown that cement-composites with GO and Al-GO can be used as a conductor, electric resistance of GO and Al-GO contained composites improved by 10.2% and 15.9% respectively when compared to the standard cement-composite. Microstructure analyzation shown the formation of Al(OH)₃ gel when Al-GO was added, which is speculated to result the smooth flow of current by improving the density of cement-composite. This implies that graphene-oxide has a possibility to be utilized as smart building materials and construction structure itself rather than just a structure.