• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.3
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• pp.201-207
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• 2021

Deep learning, a type of machine learning, performs learning while changing the weights as it progresses through each learning process. Tensor Flow and Keras provide the results of the end of the learning in graph form. Thus, If an error occurs, the result must be discarded. Consequently, existing technologies provide a function to roll back learning results, but the rollback function is limited to results up to five times. Moreover, they applied the concept of MLOps to track the deep learning process, but no rollback capability is provided. In this paper, we construct a system that manages the intermediate value of the learning process by blockchain to record the intermediate learning process and can rollback in the event of an error. To perform the functions of blockchain, the deep learning process and the rollback of learning results are designed to work by writing Smart Contracts. Performance evaluation shows that, when evaluating the rollback function of the existing deep learning method, the proposed method has a 100% recovery rate, compared to the existing technique, which reduces the recovery rate after 6 times, down to 10% when 50 times. In addition, when using Smart Contract in Ethereum blockchain, it is confirmed that 1.57 million won is continuously consumed per block creation.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.2
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• pp.31-38
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• 2021

The aim of this study is to evaluate the possibility of treating slaughterhouse by-products using microbial electrolysis cells (MECs). The diluted pig liver was fed to MEC reactors with the influent COD concentrations of 772, 1,222, and 1,431 mg/L, and the applied voltage were 0.3, 0.6, and 0.9 V. The highest methane production of 5.9 mL was obtained at the influent COD concentration of 1,431 mg/L and applied voltage of 0.9 V. In all tested conditions, COD removal rate was increased as the influent COD concentration increased with average removal rate of 62.3~81.1%. The maximum methane yield of 129~229 mL/g COD was obtained, which is approximately 80% of theoretical maximum value. It might be due to the bioelectrochemical reaction greatly increased the biodegradability of pig liver. Future research is required to improve the methane yield and digestibility through optimizing the reactor design and operating conditions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.171-179
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• 2020

In this study, a local corrosion environment monitoring was conducted using steel box specimen fabricated to be the same as actual steel bridge members. The steel box specimen that obtained the same corrosion environment as a steel bridge was classified into the upper plate, bottom plate and web plate. Atmospheric corrosion monitoring sensors(ACM sensors) were installed in each corrosion monitoring member of a steel box specimen to measure the corrosion current and examine time of wetness for each monitoring member. The time of wetness and accumulated corrosion current of each monitoring member were calculated from the measured corrosion current using ACM sensors. The corrosion environment that appeared for each of the steel box members was evaluated from monitoring corrosion environment data as the corrosion current, time of wetness, mean corrosion depth of each monitoring member. Additionally, the atmospheric corrosion environment monitoring was also conducted to compare with the local corrosion environment of steel box members. From these local corrosion environment monitoring for the steel box specimen, the relationship between the relative corrosion environment and mean corrosion depth of each steel box member was examined.

• Journal of Korean Society of Forest Science
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• v.111 no.2
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• pp.287-301
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• 2022

This study aims to propose a crane-tip control method to intuitively control the end-effector vertically or horizontally for improving the crane work efficiency and to confirm the control performance. To verify the control performance based on experimental variables, a laboratory-scale crane was manufactured using an electric cylinder. Through a forward and reverse kinematics analysis, the crane was configured to output the position coordinates of the current crane-tip and the joint angle at each target point. Furthermore, a method of generating waypoints was used, and a dead band using lateral boundary offset (LBO) was set. Appropriate parameters were selected using bang-bang control, which confirmed that the number of waypoints and LBO radius were associated with positioning error, and the cylinder speed was related to the lead time. With increased number of waypoints and decreased LBO radius, the positioning error and the lead time also decreased as the cylinder speed decreased. Using the proportional control, when the cylinder velocity was changed at every control cycle, the lead time was greatly reduced; however, the actual control pattern was controlled by repeating over and undershoot in a large range. Therefore, proportional control was performed by additionally applying velocity gain that can relatively change the speed of each cylinder. Since the control performed with in a range of 10 mm, it was verified th at th e crane-tip control can be ach ieved with only th e proportional control to which the velocity gain was applied in a control cycle of 20 ms.

• Journal of Korea Entertainment Industry Association
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• v.14 no.2
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• pp.165-176
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• 2020

Customized medical care and services timely providing effective prevention and treatment by collecting and using individuals' biomedical data are recently possible and utilized for users' health care. They are developed as the real-time health care services and information is provided to individuals by using smart phones, PC, tablet, etc. Interactive communication is supported by informing managers of analysis data and results, through collected data. It is therefore the time for constructing health care. This study attempts to prepare for patent applications of technical development at this time, by analyzing the tendency of smart wearable health care technologies, including biological signal-based health care devices and real-time health care system. Patents regarding smart wearable health care technologies were reported to have the relatively higher concentration of research development. Korea focuses on patent activities for real-time health care systems across the intervals of analysis, while U.S and European countries actively make efforts for patent activities regarding health care devices Japan conduct patent activities across health care devices and systems, based on bio-technologies. Korea has recently dominated the market of patents for bio-technologies-based health care devices and real-time health care devices and also appears to secure patents for the technologies and the market, so entry barriers to the market of smart wearable health care technologies are determined to be higher in Korea. It is important to establish the portfolios of patents, by securing patent rights for the figures of products, manufacturing methods and other related technical systems, if technologies are planned to be commercialized.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.4
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• pp.209-218
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• 2021

Studies of pore structure in shale gas reservoirs are essential to increase recovery rates, which is in the spotlight concerning unconventional resources. In this study, the distribution of pores in shale gas reservoir sample were observed using Scanning Electron Microscope Particle Analysis (SELPA), which is appropriate to analyze the distribution of particle or shape for sample in large area. A sample from the A-068 borehole drilled in the Liard Basin was analyzed; calcite is the main mineral. The pore size ranges from tens of nanometers to hundreds of micrometers and the contribution of each pore size to overall sample porosity was determined using SELPA. The distribution of pores was determined by observing the surface in the same area at magnifications of ×1000, ×3000 and ×5000. Pores less than 100 nm were observed at high magnifications and confirm that small-scale pore distribution can be analyzed and identified rapidly using SELPA. The method introduced in this study will be useful to understand pore structures in unconventional reservoirs.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.12
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• pp.889-898
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• 2022

In this paper, parallel computing method on the three-dimensional electromagnetic field is proposed. The present electromagnetic scattering analysis is conducted based on the time-harmonic vector wave equation and the finite element method. The edge-based element and 2^nd -order absorbing boundary condition are used. Parallelization of the elemental numerical integration and the matrix assemblage is accomplished by allocating the partitioned finite element subdomain for each processor. The graph partitioning library, METIS, is employed for the subdomain generation. The large sparse matrix computation is conducted by MUMPS, which is the parallel computing library based on the multi-frontal method. The accuracy of the present program is validated by the comparison against the Mie-series analytical solution and the results by ANSYS HFSS. In addition, the scalability is verified by measuring the speed-up in terms of the number of processors used. The present electromagnetic scattering analysis is performed for a perfect electric conductor sphere, isotropic/anisotropic dielectric sphere, and the missile configuration. The algorithm of the present program will be applied to the finite element and tearing method, aiming for the further extended parallel computing performance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.1-9
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• 2006

An analysis of the annual frequency of collapse(AF) is performed for each bridge pier exposed to ship collision. From this analysis, the impact lateral resistance can be determined for each pier. The bridge pier impact resistance is selected using a probability-based analysis procedure in which the predicted annual frequency of bridge collapse, AF, from the ship collision risk assessment is compared to an acceptance criterion. The analysis procedure is an iterative process in which a trial impact resistance is selected for a bridge component and a computed AF is compared to the acceptance criterion, and revisions to the analysis variables are made as necessary to achieve compliance. The distribution of the AF acceptance criterion among the exposed piers is generally based on the designer's judgment. In this study, the acceptance criterion is allocated to each pier using allocation weights based on the previous predictions. To determine the design impact lateral resistance of bridge components such pylon and pier, the numerical analysis is performed iteratively with the analysis variable of impact resistance ratio of pylon to pier. The design impact lateral resistance can vary greatly among the components of the same bridge, depending upon the waterway geometry, available water depth, bridge geometry, and vessel traffic characteristics. More researches on the allocation model of AF and the determination of impact resistance are required.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6A
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• pp.625-639
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• 2009

Experimental and analytical studies are performed on the mechanical behavior of concrete-filled tubular(CFT) truss girders for different f/L ratios. Bending tests are conducted on two CFT truss girder specimens to determine fundamental structural characteristics such as the strength and deformation properties. Nonlinear material models for CFT members subjected to an axial compressive force are compared in this paper by using the nonlinear finite element program, ABAQUS. Previous researchers have proposed several nonlinear stress-strain models of confined concrete. In this study, the nonlinear analyses are performed applying several stress-strain models for confined concrete proposed by Mander, Sakino, Han, Susantha and Ellobody, and the results are compared with the experimental results in terms of load-deflection and load-strain relationships. Based on the comparisons of the load-deflection relationships, the models proposed by Mander and Susantha provide a maximum load about 12.0~13.8% higher and that by Sakino gives a maximum load about 7.6% higher than the experimental results. The models proposed by Han and Ellobody give a maximum load only about 0.2~1.2% higher than the test results, showing the best agreement among the proposed stress-strain models. However, the load-strain relations predicted by the existing models generally provide conservative results exhibiting larger strains than the experimental data.

• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.4
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• pp.161-172
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• 2023

Autonomous driving vehicles recognize the surroundings through various sensors mounted on the vehicle and control the vehicle based on the collected information. The level of autonomous driving technology is improving due to the development of sensor technology and algorithms that process collected data, but the implementation of perfect autonomous driving technology has not been achieved. To overcome these limitations, through autonomous cooperative driving centered on infrastructure. In this study, developed a position correction sign that provides a reference for positioning of autonomous vehicles. First of all, an analysis was performed on the current status of positioning technology for autonomous driving. And measure the number of point clouds for the 1st sample consisting of two square reflective surfaces and 2nd sample that increased the vertical length of each reflective surface. Experimental results show that both primary and secondary products are installed at least 15 m apart It could be recognized as a sensor, and it was confirmed that the secondary production that increased the length of the top and bottom had a higher number of point clouds than the primary production and better expressed the shape of the facility.