• Advances in Computational Design
• /
• v.7 no.4
• /
• pp.281-295
• /
• 2022

Tensile property is one of the excellent properties of ultra-high performance concrete (UHPC), and uniaxial tensile test is an important and challenging mechanical performance test of UHPC. Traditional uniaxial tensile tests of concrete materials have inherent defects such as initial eccentricity, which often lead to cracks and failure in non-test zone, and affect the testing accuracy of tensile properties of materials. In this paper, an original integrated design scheme of mould and end fixture is proposed, which achieves seamless matching between the tension end of specimen and the test fixture, and minimizes the cumulative eccentricity caused by the difference in the matching between the tension end of specimen and the local stress concentration at the end. The stress analysis and optimization design are carried out by finite element method. The curve transition in the end of specimen is preferred compared to straight line transition. The rationality of the new integrated design is verified by uniaxial tensile test of strain hardening UHPC, in which the whole stress-strain curve was measured, including the elastic behavior before cracking,strain hardening behavior after cracking and strain softening behavior.

• Earthquakes and Structures
• /
• v.13 no.5
• /
• pp.455-464
• /
• 2017

This paper develops a new method for analyzing the structural seismic behavior of single-layer reticulated shells based on exponential strain energy density (ESED). The ESED method reveals a characteristic point from a relationship between ESED sum and peak seismic acceleration. Then, the characteristic point leads to an updated concept of structural failure and an ESED-based criterion for predicting structural failure load. Subsequently, the ESED-based criterion and the characteristic point are verified through numerical analysis of typical single-layer reticulated shells with different configurations and a shaking table test of the scale shell model. Finally, discussions further verify the rationality and application of the ESED-based criterion. The ESED method might open a new way of structural analysis and the ESED-based criterion might indicate a prospect for a unified criterion for predicting seismic failure loads of various structures.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.5
• /
• pp.1935-1944
• /
• 2018

With the increase of the production of energy from renewable, it becomes important to look at techniques to store this energy. Therefore, a single winding bearingless flywheel motor (SWBFM) specially for flywheel energy storage system is introduced. For the control system of SWBFM, coupling between the torque and the suspension subsystems exists inevitably. It is necessary to build a reasonable radial force mathematical model to precisely control SWBFM. However, SWBFM has twelve independently controlled windings which leads to high-order matrix transformation and complex differential calculation in the process of mathematical modeling based on virtual displacement method. In this frame, a Maxwell tensor modeling method which is no need the detailed derivation and complex theoretical computation is present. Moreover, it possesses advantages of universality, accuracy, and directness. The fringing magnetic path is improved from straight and circular lines to elliptical line and the rationality of elliptical line is verified by virtual displacement theory according to electromagnetic torque characteristics. A correction function is taken to increase the model accuracy based on finite element analysis. Simulation and experimental results show that the control system of SWBFM with radial force mathematical model based on Maxwell tensor method is feasible and has high precision.

• Journal of Technology Innovation
• /
• v.16 no.2
• /
• pp.167-200
• /
• 2008

This work firstly aims to analyse how the policy makers had been able to sort out the two policy issues, 'how did the MOST establish the inter-departmental project' and 'why did the MOST give a legal power to the private experts', in the process of policy making for Highly Advanced National(HAN) project, called G7 Project, which had been implemented for 10 years in 1990s. Then, this will discuss the policy implications available to the similar policy areas in the future. The result shows that the agenda setting of the G7 Project, one of the successful national R&D projects in Korea, had been initiated by a few leaders who had have the perspective of pioneer. In addition, this explains that private experts had more played than civil servant did in the process of policy formation, which had been backed up by the R&D plannin4g system then introduced in R&D management process for the frist time. This case study will provide policy makers with the opportunities to remind 'the necessities of the policy management by the system not actors', 'more effective management of distribution policy' and 'the better role of related experts in the policy making process'. Also, above issues will make both the practitioners and the researchers again consider how to improve the rationality and effectiveness of the policy making process in the field of science and technology.

• Journal of Korea Port Economic Association
• /
• v.35 no.4
• /
• pp.121-146
• /
• 2019

This study investigates the innovation resistance when blockchain technology is introduced for the shipping and port industry. For the development of a research model with suitable measures, we review and focus on innovation resistance factors with the blockchain technology derived from previous studies. In this research, we consider four factors (innovation characteristics, consumer characteristics, environmental characteristics, and cost characteristics) with innovation resistance as dependent variables. The innovation characteristics include relative benefits, complexity, and perceived risk. The consumer characteristics consider attitude toward existing products, innovation, and self-efficacy. Social impact variables are environmental characteristics and rationality of cost. In the statistical analysis, we set up eight hypotheses to test the significances between variables and find the following four empirical results. First, the relative advantage and the perceived risk have a significant effect on innovation characteristic, but the complexity of this characteristic has no significant effect on innovation resistance. Second, the rationality of cost has no significant effect on innovation resistance. Third, the attitude toward existing products has a positive effect and the innovation of the consumer characteristic has a negative effect on innovation resistance, while the self-efficacy has no significant effect. Finally, the social impact has a significant effect on innovation resistance to blockchain in the shipping and port industry.

• Journal of Contemporary Eastern Asia
• /
• v.20 no.1
• /
• pp.120-133
• /
• 2021

This paper proposes an interpretation of Charles Ess's pros hen pluralism, especially concerning what constitutes the single end point (hen) toward which the pluralistic viewpoints converge (pros). The single end point, I argue, is constituted by an empirical social reality that obtains in the world at a particular period. In other words, it is the fact that we happen to agree largely and broadly on several ethical issues that serves as the end point in Ess's theory. The reason is that humans happen largely to share the same goals and values qua human beings, such as the desire for communication and cooperation with one another. It is not their rationality, or any other permanent and ideal characteristic, that serves as the source of normativity for human beings, but rather the contingent facts that obtain at a particular place and time, facts that humans happen to agree on. This raises an obvious objection of what to do with those who might cherish a very different set of values. The answer is that the globalized nature of the world today, especially deepened by information technology, makes it increasingly difficult for any groups to remain isolated. This does not imply, however, that disagreements are not possible. On the contrary, disagreements are a part of the whole process from the beginning. At the theoretical level, there is always a need for those who disagree on the theoretical issues rationally to persuade one another. This is also part of the empirical reality referred to earlier.

• Journal of Power Electronics
• /
• v.16 no.5
• /
• pp.1698-1705
• /
• 2016

In this paper, a hardware-in-the-loop simulation platform for MMCs is established, which connects a real time digital simulator (RTDS) and a designed MMC controller with optical fiber. In this platform, the converter valves are simulated with a small time step of 2.5 microsecond in the RTDS, and multicore technology is implemented for the controller so that the parallel valve control is distributed between different cores. Therefore, the designed controller can satisfy the requirements of real-time control. The functions of the designed platform and the rationality for the designed controller are verified through experimental tests. The results show that different modulation modes and various control strategies can be implemented in the simulation platform and that each control objective can been tracked accurately and with a fast dynamic response.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.8
• /
• pp.1908-1916
• /
• 2015

In reacting to disasters, rationality only relies on human experience leads to huge lose. Accordingly, in order to prepare for national emergency due to diverse and complicated disaster, the government needs to transfer into cooperation-based disaster management system using smart UT. Hence, this paper analyzes current disaster management systems' problems and considers resolution in fulfilling the requirement in safety. Then, it suggests service structure for technically effective UT utilization and considers u-Gov's role in preparing unpredictable disasters.

• Geomechanics and Engineering
• /
• v.32 no.3
• /
• pp.245-254
• /
• 2023

Through qualitative analysis and quantitative analysis, the contradictory conclusions about the stability of the settled goaf with two-layer coal seams subject to building load were obtained. Therefore, it is necessary to combine the additional stress method and numerical simulation to further analyze the foundation stability. Through borehole analysis and empirical formula analogy, the height of water-conducting fracture zone in No.4 coal and No.9 coal were obtained, providing the calculation range of water-conducting fracture zone for numerical simulation. To ensure the accuracy of the elastic modulus of broken gangue, the stress-strain curve were obtained by broken gangue compression test in dried state of No.4 coal seam and in soaking state of No.9 coal seam. To ensure the rationality of the numerical simulation results, the actual measured subsidence data were retrieved by numerical simulation. FISH language was used to analyze the maximum building load on the surface and determine the influence depth of building load on the foundation. The critical building load was 0.16 MPa of No.4 settled goaf and was 1.6 MPa of No.9 settled goaf. The additional stress affected the water-conducting fracture zone obviously, resulted in the subsidence of water-conducting fracture zone was greater than that of bending subsidence zone. In this paper, the additional stress method was analyzed by numerical simulation method, which can provide a new analysis method for the treatment and utilization of the settled goaf.

• Geomechanics and Engineering
• /
• v.18 no.4
• /
• pp.439-448
• /
• 2019

The bearing capacity of roadside support is the key problem in gob-side entry retaining technology. To study the cooperative bearing characteristics of the roof-roadside support-floor along the gob-side entry retaining, a mechanical model of the composite structure of the roof-roadside support-floor was first established. A method for determining the structural parameters of gob-side entry retaining was then proposed. Based on this model, adaptability analysis of roadside support was carried out. The results showed that the reasonable width of the gob-side entry roadway was inversely proportional to the mining height, and directly proportional to the bearing strength of the roof and floor. And the reasonable width of the "flexible-hard" roadside support was directly proportional to its own strength, and inversely proportional to the width of the gob-side entry retaining. When determining the position and size of the roadside support along the gob-side entry retaining, the surrounding rock environment should be fully considered. Measured results from case study also show the rationality of the model and calculation method.