• Earthquakes and Structures
• /
• v.11 no.5
• /
• pp.823-840
• /
• 2016

The plastic hinge lengths of beams and columns are a critical demand parameter in the nonlinear analysis of structures using the finite element method. The numerical model of a plastic hinge plays an important role in evaluating the response and damage of a structure to earthquakes or other loads causing the formation of plastic hinges. Previous research demonstrates that the plastic hinge length of reinforced concrete (RC) columns is closely related to section size, reinforcement ratio, reinforcement strength, concrete strength, axial compression ratio, and so on. However, because of the limitations of testing facilities, there is a lack of experimental data on columns with large section sizes and high axial compression ratios. In this work, we conducted a series of quasi-static tests for columns with large section sizes (up to 700 mm) and high axial compression ratios (up to 0.6) to explore the propagation of plastic hinge length during the whole loading process. The experimental results show that besides these parameters mentioned in previous work, the plastic hinge of RC columns is also affected by loading amplitude and size effect. Therefore, an approach toward considering the effect of these two parameters is discussed in this work.

• Applied Microscopy
• /
• v.46 no.1
• /
• pp.37-44
• /
• 2016

In this study $TiO_2$/reduced graphene oxide ($TiO_2/rGO$) bipyramid with tunable nanostructure was fabricated by two-step solvothermal process and subsequent heat-treatment in air. The as-synthesized anatase $TiO_2$ nanocrystals possessed morphological bipyramid with exposed dominantly by (101) facets. Polyethylenimine was utilized during the combination of $TiO_2$ and graphene oxide (GO) to tune the surface charge, hindering the restack of graphene during solvothermal process and resulting in 1 to 5 layers of rGO wrapped on $TiO_2$ surface. After a further calcination, a portion of carbon quantum dots (CQDs) with a diameter about 2 nm were produced owing to the oxidizing and cutting of rGO on $TiO_2$. The as-prepared $TiO_2/rGO$ hybrid showed a highly photocatalytic activity, which is about 3.2 and 7.7 times enhancement for photodegradation of methyl orange with compared to pure $TiO_2$ and P25, respectively. We assume that the improvement of photocatalysis is attributed to the chemical bonding between rGO/CQDs and $TiO_2$ that accelerates photogenerated electron-hole pair separation, as well as enhances light harvest.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.12
• /
• pp.5405-5411
• /
• 2011

The effects of heat input (1.5~3.6 kJ/mm) and post weld heat treatment (PWHT, $600^{\circ}C$, 40hr.) on the TMCP HSB600 steel weldments made by GMAW process were investigated. The tensile strengths and hardness of as-welded specimens were decreased as heat input increased, but CVN (Charpy V-Notch) impact energy did not show any differences. The fine-grained acicular ferrite was mainly formed in the low heat input while polygonal and side plate ferrites were dominated in the high heat inputs. Meanwhile, tensile strength and hardness of PWHT weldments were decreased due to the coarsening and globular of microstructure as well as reduction of residual stresses.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.2
• /
• pp.269-278
• /
• 2016

In order to maintain customer voltages within allowable limit($220{\pm}13V$) as much as possible, tap operation strategy of SVR(Step Voltage Regulator) installed in distribution system is very important, considering the scheduled delay time(30 sec) of SVR. However, the compensation of BESS(Battery Energy Storage System) during the delay time of SVR is being required because the customer voltages in distribution system interconnected with PV(Photovoltaic) system have a difficultly to be kept within allowable limit. Therefore, this paper presents the optimal voltage stabilization method in distribution system by using coordination operation algorithm between BESS and SVR. It is confirmed that customer voltage in distribution system can be maintained within allowable limit($220{\pm}13V$).

• Journal of the Korean Society of Industry Convergence
• /
• v.26 no.6_3
• /
• pp.1315-1323
• /
• 2023

Rehabilitation assistive devices not only assist the rehabilitation therapy and daily life of the disabled and the elderly, but also assist the labor of their caregivers, so various functions are required to improve their quality of life. In this study, a design method considering its practicality is introduced for an active rehabilitation assistive device that can perform both standing and walking assistance by driving various actuators. For this purpose, the force required to assist standing was calculated using statics with the body segmentation method. Also, the overturning stability of the device was verified for various physical conditions and postures. The actuator in the active rehabilitation assistive device was operated by a patient using a graphical user interface in an embedded computer and a touch panel for easy usage. The detailed design was performed for implementation through the help of 3D-CAD and the finite element analysis, and a prototype was produced. Finally, it was proven that the design goal was satisfied by experimental validation.

• ALGAE
• /
• v.39 no.3
• /
• pp.207-222
• /
• 2024

In this study, the regulation of abscisic acid (ABA) on cell growth and lipid biosynthesis was investigated under salt-induced stress in Chlorella pyrenoidosa. It is found that as suffering from only salt stress, although the lipid content of single cell was improved, the inhibitory effects of stress on cell proliferation was visible. When the algal cells were exposed to salt stress and ABA conditions, lipid productivity was increased (45.35 mg L^-1 d^-1) by 1.17-fold compared to that of control cells (20.91 mg L^-1 d^-1), and the inhibition to cell growth was relieved. Transcriptomic analysis revealed that after adding ABA, these genes involved in antioxidant activity, jasmonic acid (JA) biosynthesis, and lipid biosynthesis were upregulated. Subsequently, we observed that the levels of glutathione, total antioxidant capacity, trehalose, and JA were elevated and the levels of reactive oxygen species were reduced. This study presents an effective approach to improve lipid production in algal cells, a new mechanism on that ABA alleviates intracellular oxidative stress through JA signaling pathway was elaborated.

• Journal of Technologic Dentistry
• /
• v.12 no.1
• /
• pp.23-45
• /
• 1990

This study aimed at inquiring into the basic theory on co-operative education, grasping and analyzing the present situation of the junior health college, the present condition of co-operative education and into problem. and seeking to find a solution to activate the co-operative edcation of the junior health colleges. For this purpose this study compared the co-operative education system in our country with that of foreign countries revolving around the related literature to co-operative education, analyzed it, and the pointed out its problem. And this study classified into the solution of establishing co-operative education system, the solution of consolidating the on-the-spot training system, the solution to activate the co-operative education of the junior health college. First this study suggested three methods as a part of establishing co-operative education system as below. 1. The need to set up the ideology concerning co-operative education. 2. The construction of the advisory committee for co-operative education. 3. The establishment of an agency for co-operative education. And this study suggested nine methods as the method of consolidating the on-the-spot training as below. 1. The execution of the basic research for the on-the-spot training. 2. The reorganization of the existing curriculum into the curriculum the industrial organization requires. 3. The establishing of the system in a closer cooperation with the industrial organization for the on-the-spot training. 4. The participation in solving commonly the problems of the industrial organization and in education. 5. The establishing of the guidance system assuming exclusive charge of the on-the-spot training. 6. The submission of the evaluation sheet for the on-the-spot training. 7. The extension of the period of the on-the-spot training and the reorganization of an educational system. 8. The persistent support for the on-the-spot training at the governmental dimension. 9. The securing of the educational dost spent on the on-the-spot training and the imposition of benefits on the industrial organization.

• Journal of The Korean Association of Information Education
• /
• v.8 no.2
• /
• pp.213-224
• /
• 2004

Textbooks are the basic materials for school education and the best instruments that the teachers can use. The textbooks for information and communication technology education that are authorized by the superintendent of schools are currently used in the elementary schools and the various kinds of the ICT textbooks are adopted in accordance with the cities and provinces. In this study, we make a comparative study of the 11 ICT textbooks for year 4 students from the view points of the present conditions, the organizations, and the contents. Also, using Romey's method we investigate them whether their contents are suitable for the inquiring activities. We expect that our study will be the basis of the development of the next authorized ICT textbooks and contribute to the ICT education.

• Journal of Practical Engineering Education
• /
• v.15 no.1
• /
• pp.223-232
• /
• 2023

The Work-Study parallel program has been promoted as a key policy to resolve the mismatch between industrial sites and school education and realize a competency-centered society, and as of December 2022, 16,664 companies participated in the training. Learning companies play a very important role as education and training supply organizations that conduct field training. In this study, for the evaluation of learning companies participating in work-study program, the authors derive important factors that determine the quality of on-site education and training by analyzing the cognitive structure of experts in charge of the company and present evaluation indicators for learning enterprises. Therefore, it is intended to lay the foundation for promoting the quality of work-study parallel program.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.6
• /
• pp.695-702
• /
• 2023

The purpose of this study is to develop an early childhood artificial intelligence education programs in kindergartens. In order to achieve the purpose of the study, a four-step program development procedure was taken: documentary analysis, program design and development, execution, and assessment. This study presented the purpose and goals, educational content, teaching-learning methods, and evaluation of the early childhood artificial intelligence education program in kindergarten. By implementing an artificial intelligence education in the process of developing the program, the practicality and utilization of the program were secured. This study is meaningful in that it derives practical support measures to apply and activate artificial intelligence education programs in the field of early childhood education.