• Journal of Korean Association for Spatial Structures
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• v.19 no.1
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• pp.75-82
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• 2019

In the precedent study, the retractable-roof spatial structure was selected as the analytical model and a tuned mass damper (TMD) was installed to control the dynamic response for the earthquake loads. Also, it is analyzed that the installation location of TMD in the analytical model and the optimal number of installations. A single TMD mass installed in the analytical model was set up 1% of the mass of the whole structure, and the optimum installation location was derived according to the number of change. As a result, it was verified that most effective to install eight TMDs regardless of opening or closing. Thus, in this study, eight TMDs were installed in the retractable-roof spatial structure and the optimum mass ratio was inquired while reducing a single TMD. In addition, the optimum mass distribution ratio was identified by redistributing the TMD masses differently depending on the installation position, using the mass ratio of vibration control being the most effective for seismic load. From the analysis results, as it is possible to confirm the optimum mass distribution ratio according to the optimum mass ratio and installation location of the TMD in the the retractable-roof spatial structure, it can be used as a reference in the TMD design for large space structure.

• Journal of Korea Planning Association
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• v.54 no.7
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• pp.58-69
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• 2019

This study suggested the necessity of introducing the future-oriented new industrial complex as a way to enhance the competitiveness of the industrial complex in response to the industrial ecosystem change caused by the 4th industrial revolution. To evaluate the location suitability for the new industrial complex, location indices were developed in this study. The flexibility of location and connectivity to neighboring areas of the future-oriented new industrial complexes were the focused subjects of this study. In-depth expert consultation and Delphi survey were conducted to construct an index system and to measure the indices. Afterwards, the AHP analysis was conducted to elucidate the weighting by indicators. As a result, the indicators of industrial innovation environment were the most important in the major category. In addition, the convenience of workers, especially urban environment, was analyzed as an important factor for success of the future-oriented new industrial complex. The indicators which are closely related to the concept and purpose of the future-oriented new industrial complex turned out to have the higher weight compared to other indicators. From the point of view of the developers of the industrial complexes or tenant companies, the implications for deriving suitable locations for development of industrial complexes among urban under-utilized sites are suggested. Furthermore, It is expected that the government will be able to apply the development system to stimulate the development of these new industrial complexes and to prepare guidelines for selecting locations.

• Composites Research
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• v.34 no.4
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• pp.257-263
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• 2021

Composite materials have been widely applied for fabricating pressure vessels used for storing gaseous and liquid fuel because of their high specific stiffness and specific strength. Accordingly, the accurate measurement of their mechanical property, particularly the burst pressure or fracture strain, is essential prior to the commercial release. However, verification of the safety of composite pressure vessels using conventional test methods poses some limitations because it may lead to the deformation of the load transferring media or provoke an additional energy loss that cannot be ignored. Therefore, in this study, the segment-type ring burst test device was designed considering the theoretical load transferring ratio and applicable displacement of the vertical column. Moreover, to verifying the uniform distribution of pressure of the segment type ring burst test device, the hoop stress and strain distribution of ring specimens were compared with that of the hydraulic pressure test method via FEM. To conduct a simulation of the fracture behavior of the composite pressure vessel, a Hashin failure criterion was applied to the ring specimen. Furthermore, the fracture strain was also measured from the experiment and compared with that of the result from the FEM.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.119-128
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• 2020

An ultrasonic multiple scattering simulation using cross-section of fine dust particles were proposed. These days, along with awareness of air pollution, social interest in fine dust is increasing. In the construction field, awareness of fine dust is increasing, and research on preparing various countermeasures is underway. The light scattering method fine dust meter currently in use is affected by environmental factors such as relative humidity, and reliability problems in terms of accuracy are continuously reported. However, the transmission of ultrasonic waves can directly reflect the physical change of the medium based on the mechanical wave. Using these advantages of ultrasonic waves, fine dust measurement simulation was performed using the scattering cross section and ultrasonic multiple scattering theory. The shape data of the fine dust particles were collected using a SEM (Scanning Electron Microscope), and a cross-section according to the fine dust particles was derived through numerical analysis. As a result of signal processing, the error for the number density corresponding to each cross-section is minimum 19, maximum 3455.

• Journal of the Korean Applied Science and Technology
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• v.38 no.1
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• pp.300-308
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• 2021

In this study, 3D networked poly(sodium acrylate) gel was polymerized and controlled with the crosslinking environment to evaluate the mechanical properties and swelling behavior. In general, as the degree of crosslinking in a pre-gelled solution increases, the swelling ratio of the 3D networked gel decrease while the mechanical strength of the gel increases. Interestingly, this study demonstrates that the polymerization and crosslinking efficiency in gelling process could be depended on the crosslinking environment by evaluating the number of elastically cross-links in 3D networked gel. As a result, the number of elastically corss-links would be changed with 3.6 times as varying of the crosslinking environment while keeping the degree of crosslinking. It is expected that the 3D networked gel would be optimized as an effective absorbing agent for VOCs by using the gel evaluation method based on the number of elastically cross-links.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.6
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• pp.214-227
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• 2021

The purpose of this study is to find the driving difficulty of automated vehicles in terms of road infrastructure operation. It was judged out of this study that the level of automated driving would be enhanced if the road situation recognition ability was advanced through the presentation of infrastructure information during the difficult driving situations. The difficulty evaluation index was divided into three stages, and a survey of experts and an AHP were conducted. The result of the AHP showed that the driving difficulty of the interrupted flow was much higher than that of the uninterrupted flow. The AHP results also showed that and the driving difficulty of unsignalized intersections and roundabouts under an interrupted flow was evaluated as the highest. The top six driving situations with high difficulty were also evaluated to occur under unsignalized intersections and roundabouts.

• Korean small business review
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• v.43 no.1
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• pp.35-50
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• 2021

The youth job problem is becoming more serious due to COVID-19. To solve this problem, a "good job platform" was proposed that allows young job seekers to easily and conveniently find excellent SMEs they want to work for. This study developed a "good job self-assessment model" that grasps the preferred jobs of young job seekers and evaluates SMEs and applied them in the platform. In this process, the characteristics of good jobs from the viewpoint of job seekers were identified through conjoint analysis from the viewpoint of salary level, performance compensation, working environment, corporate soundness, and organizational culture. Next, the importance of 13 detailed evaluation items was reflected through AHP for industry, academia, and research experts. The self-assessment model of this study can be used as a tool to improve awareness that changes the SME environment into a job favored by young job seekers. As a result, it could provide an opportunity to change the job problem from providing cost-oriented support to a qualitative solution.

• Journal of the Korean Geotechnical Society
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• v.23 no.3
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• pp.141-147
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• 2007

Various approaches have been developed for the dynamic response analysis of piles. In one of the approaches, the soil-pile interaction is approximated by using parallel nonlinear springs, namely the p-y curves. Currently available p-y curve recommendations are based on static and cyclic lateral load tests. Other researchers have attempted to extend the p-y curves by incorporating the effects of liquefaction on soil-pile interaction and derived scaling factors of p-y curves to account fur the liquefaction. However, opinions on the scaling factors vary. In this study, the sealing factors, which reflect the variation of the elastic moduli of surrounding soils, were established combining the relationship between excess pore pressures and the natural frequencies of a soil-pile system obtained from Ig shaking table tests and the relationship between the elastic moduli of surrounding soils and the natural frequencies of a soil-pile system obtained from numerical analyses. As a result, the scaling factors were presented in an exponential function.

• Journal of the Korea Society of Computer and Information
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• v.14 no.6
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• pp.107-116
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• 2009

Even though there are growing numbers of IT utilization in many organizations, they are required to use only constrained amount of resources due to the decrease in IT Investment, following economic recession. Besides, the CEOs in those organizations are required to assess how IT Investment, which has been gradually increased during the industrial growth, affects their organizational performances. Thus, they began to enforce IT governance so as to measure IT efficiency and minimize business risks. As a result, they improved the decision making process of IT Investment, enforced IT value assessment, and established the IT Investment-performance evaluation process as well. In this article, I aimed to make it clear how IT Investment affects the IT Performance by analyzing the effects of the factors constituting the IT Investment managing system and the Process Maturity on the User Satisfaction. This analysis can suggest a practical IT Investment-performance model, which can increase organizational performances.

• Explosives and Blasting
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• v.41 no.4
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• pp.41-50
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• 2023

This study, a vertical double-deck method using an electronic detonator was applied to increase excavation volume and reduce blast pollution. In the double deck method, there is a possibility that blasting efficiency may be reduced if bottom deck blasting is carried out without the free surface being completely formed after upper deck blasting. And for this reason, the blasting efficiency of the double deck method varies depending on the deck delay time. Therefore, in this study, we proposed four deck delay times applying 1 to 5 times the hole delay time. And blasting efficiency was evaluated according to fragmentation analysis. As a result of the fragmentation evaluation, the fragmentation of pattern 4 (deck delay time = hole delay time×5) was the best, but it was confirmed that fragmentation efficiency increased significantly from pattern 3 (deck delay time = hole delay time×3). Accordingly, it is analyzed that when blasting a vertical double deck, the deck delay time must be at least three times the hole delay time to obtain an efficient blasting effect.