• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.4
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• pp.587-594
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• 2023

In this paper, we present the design and optimization process of an on-body microstrip patch antenna with a paired T-type defect for monitoring fracture recovery of human legs. This antenna is designed to be light, thin and compact despite the improvement of return loss and bandwidth performance by adjusting the size of the T-type defect. The structure around the applied human leg is structured as a 5-layer dielectric plane, and the complex dielectric constant of each layer is calculated using the 4-pole Cole-Cole model parameters. In a normal case without bone fracture, the return loss of the on-body antenna is -66.71dB at 4.0196GHz, and the return loss difference ΔS₁₁ is 37.95dB when the gallus layer have a length of 10.0mm, width of 1.0mme, and height of 2.0mm. A 3'rd degree polynomial is presented to predict the height of the gallus layer for the change in return loss, and the polynomial has a very high prediction suitability as RSS = 1.4751, R² = 0.9988246, P-value = 0.0001841.

• Journal of the Korea Society of Computer and Information
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• v.28 no.8
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• pp.103-109
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• 2023

In this paper, we propose a smart wall switch based on IEEE 802.11b/g/n standard 2.4GHz band communication. As the 4th industrial era evolves, smart home solution development is actively underway, and application cases for smart wall switches are increasing. Most of the Chinese products that preoccupy the market through price competitiveness use Bluetooth and Zigbee communication switches. However, while ZigBee communication is low power, communication speed is slower than Bluetooth and network configuration through a separate hub is additionally required. The Bluetooth method has problems in that the communication range and speed are lower than Wi-Fi communication, the communication standby time is relatively long, and security is weak. In this study, an IEEE 802.11b/g/n smart wall switch applied with Wi-Fi communication technology was developed. In addition, through the two-wire structure, it is designed so that no additional cost is incurred through the construction of a separate neutral line in the building. The result of the study is more than 30% cheaper than the existing wall switch, so it is judged that it will be able to preoccupy the market not only in terms of technological competitiveness but also price competitiveness.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.65-85
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• 2023

The use of TBM (Tunnel boring machine) has increased worldwide due to its performance together with the benefit of being safely and environmentally friendly compared to conventional tunneling. In particular, EPB (Earth Pressure Balanced) TBM is widely used because it can be applied to various grounds compared to Open TBM. Also EPB TBM has a simple mechanical structure and advantages in cost, requires less ground area than Slurry TBM. EPB TBM has advantages in soft ground, and more importantly, can extend its applicability by use of appropriate soil conditioning, which improves mechanical and hydrological properties of excavated soil and increases the excavation performance of EPB TBM. Various studies suggested the proper mixing ratio and injection ratio, but almost they are limited to laboratory test under atmospheric pressure such as slump test. Actual field conditions may differ depending on the ground and mechanical condition. In this study, first the amount of used soil conditioning used in the field with various grounds from hard rock to soft ground was estimated through laboratory tests and compared with the estimate in design stage. And also it was compared with the amount used during actual excavation. In addition, experience of soil conditioning for the problems of cutter head clogging and groundwater inrush that occurred during excavation is discussed. Finally, lesson learned for the use of soil conditioning in difficult ground condition such as mixed ground are reviewed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.157-173
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• 2023

Although this site is designed with a non-vibration excavation method for a section of 265 m, there are concerns about decline of constructability and economic feasibility. For this reason, the low-vibration electronic detonator blasting method was suggested. To evaluate the applicability of the low-vibration electronic detonator blasting method, the damage range of blasting vibration of low-vibration electronic detonator blasting applied just before the site (suggestion I) and low-vibration electronic detonator blasting constructed close range the subway like this site (suggestion II) was analyzed. As a result of comparing the blasting vibration damage ranges of the two suggestions, the damage range of suggestion II was calculated more conservatively. Considering the specificity of the close range of this site, suggestion II was selected for design change for safer construction. As a result, it is predicted that there will be no damage to the structure even if the 72 m section out of the non-vibration excavation 265 m section is changed to the Low-vibration electronic detonator blasting. And it is evaluated that high economic benefits can be obtained because the total expected excavation period can be reduced by 144 days from 662.5 days.

• Journal of Service Research and Studies
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• v.12 no.3
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• pp.1-25
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• 2022

This study was conducted for technology development and industrial and enterprise system design for the sustainable life of mankind. Human society is facing a crisis. As the power of mankind has increased due to the development of nuclear weapons and information and communication technologies, the risk of human society has greatly increased. The value of growth and freedom is increasing due to capitalism and democratic systems, so technological innovation is accelerating, and industries and companies are growing significantly. New technologies and industries can greatly develop human society and put it at risk. This study was conducted with the aim of redesigning technology, industry, and enterprise systems so that humans who live on Earth can be more sustainable for a longer time. It presented a practical alternative for a long-term sustainable human society. It suggested alternatives for what philosophy and methodology should be developed for the whole of humanity and in each individual national society, for developing technologies, fostering industries, and operating corporate systems. First of all, the problems of the technology development system, industrial system, and enterprise system of human society were analyzed. The characteristics and problems were analyzed in terms of sustainability of human society. The necessary and sufficient conditions for an alternative system to solve the raised problems were derived. A system that satisfies these conditions was designed and presented. The alternative system was named as a servicism system as a system based on the service philosophy. The structure, operation model, and implementation plan of the new technology industry enterprise system were presented. In the future, follow-up studies are needed to be concreted at the level of individual countries and human society as a whole.

• Journal of the Korean Geotechnical Society
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• v.23 no.7
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• pp.65-76
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• 2007

Recently, there have been many construction projects on soft ground with growth of industry and various construction problems concerning soft soil behavior also have been reported. Especially, foundation piles of abutments and (or) buildings which were constructed on the soft ground have been suffering from a lot of stability problems of inordinary displacement due to lateral flow of soft ground. Although many researches for this phenomena have been carried out, it is still difficult to assess the mechanism of lateral flow on soft ground quantitatively. And reliable design method for judgement of lateral flow occurrence is not established yet. In this study, PNN (probabilistic neural network) and CNN (committee neural network) theories were applied for judgment of lateral flow occurrence based on eat data compiled from Korea and Japan. Predictions of PNN and CNN models for new data which were not used during model development are compared with those predicted by conventional empirical methods. It was found that the developed PNN and CNN models can predict more precise and reliable judgment of lateral flow occurrence than conventional empirical methods.

• Journal of the Korean Geotechnical Society
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• v.22 no.6
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• pp.15-26
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• 2006

Although numerous investigations have been performed over the years to predict the behavior and bearing capacity of piles, the mechanisms are not yet entirely understood. The prediction of bearing capacity is a difficult task, because large numbers of factors affect the capacity and also have complex relationship one another. Therefore, it is extremely difficult to search the essential factors among many factors, which are related with ground condition, pile type, driving condition and others, and then appropriately consider complicated relationship among the searched factors. The present paper describes the application of Artificial Neural Network (ANN) in predicting the capacity including its components at the tip and along the shaft from dynamic load test of the driven piles. Firstly, the effect of each factor on the value of bearing capacity is investigated on the basis of sensitivity analysis using ANN modeling. Secondly, the authors use the design methodology composed of ANN and genetic algorithm (GA) to find optimal neural network model to predict the bearing capacity. The authors allow this methodology to find the appropriate combination of input parameters, the number of hidden units and the transfer structure among the input, the hidden and the out layers. The results of this study indicate that the neural network model serves as a reliable and simple predictive tool for the bearing capacity of driven piles.

• Korea Science and Art Forum
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• v.23
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• pp.149-162
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• 2016

Here are background, method, scope, main contents of this research. As the interests increased in recent about the construction in complex and diverse areas, construction is locally connected to human life like to coexistence of the technology and culture. The local development should not be fragmentary construction to improve local recycling ability. Local society should be inherited by modern cultural perspective through a variety of local culture and coexistence. Effective decision making analysis is necessary to build a livable area with a combination of high-tech industry. For this reason, this paper will study the political analysis for decision making at the planning stage of construction in point of fusion of technology and culture by using unstructured data analysis. Conclusion is as in the following. Local planning stage of construction describes diverse meanings of intangible and intangible factors as political factor. Technology factors have various qualitative and quantitative factors in construction field. Understanding decision making at the planning stage of construction means not only visible 'technology factor' such as structure, method, shape, and so on, but also invisible 'culture factor' such as spirit of age, religion, learning, and life-style reflected in formation process of space, and insight of brain power about art.

• Composites Research
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• v.36 no.3
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• pp.211-216
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• 2023

When designing ships and aircraft structures, it is important to design them to satisfy weight reduction and strength. Currently, studies related to topology optimization using 3D printed composite materials are being actively conducted to satisfy the weight reduction and strength of the structure. In this study, structural analysis was performed to analyze the applicability of 3D printed composite materials to the flight control surface, one of the parts of an aircraft or unmanned aerial vehicle. The optimal topology shape of the flight control surface for the bending load was analyzed by considering three types (hexagonal, rectangular, triangular) of the topology shape of the flight control surface. In addition, the bending strength of the flight control surface was analyzed when four types of reinforcing materials (carbon fiber, glass fiber, high-strength high-temperature glass fiber, and kevlar) of the 3D printed composite material were applied. As a result of comparing the three-point bending test results with the finite element method results, it was confirmed that the flight control surface with hexagonal topology shape made of carbon fiber and Kevlar had excellent performance. And it is judged that the 3D printed composite can be sufficiently applied to the flight control surface.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.511-518
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• 2009

This study was intended to compare and evaluate the adhesion of High flowing Self-compacting Concrete (HSCC), Conventional Concrete (CC) and deformed bar based on concrete strength 3 (30, 50 and 70 MPa), among the factors affecting the bond strength between concrete and rebar, after fabricating the specimen by modifying the rebar position at Horizontal reinforcement at bottom position (HB), horizontal reinforcement at top position (HT) and vertical reinforcement type (V). As a result of measuring bond strength of HB/HT rebar to evaluate the factor of the rebar at top position, the bond strength of HB/HT rebar at 50 and 70 MPa was 1.3 or less and at 30 MPa, HSCC and CC appeared to be 1.2 and 2,1, respectively. Thus, when designing the anchorage length according to the concrete structure design standard (2007) at HSCC 30, 50 and 70 MPa, it would be desirable to reduce the correction factor of anchorage length of the horizontal reinforcement at top position, which is suggested for the reinforcement at top position, to less than 1.3 of CC.