• Journal of Power Electronics
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• v.18 no.2
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• pp.482-491
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• 2018

The practical design methodology of a three-phase dual active bridge (3ph-DAB) converter applied to low voltage direct current (LVDC) applications is proposed by using a mathematical model based on the steady-state operation. An analysis of the small-signal model (SSM) is important for the design of a proper controller to improve the stability and dynamics of the converter. The proposed lead-lag controller for the 3ph-DAB converter is designed with a simplified SSM analysis including an equivalent series resistor (ESR) for the output capacitor. The proposed controller can compensate the effects of the ESR zero of the output capacitor in the control-to-output voltage transfer function that can cause high-frequency noises. In addition, the performance of the power converter can be improved by using a controller designed by a SSM analysis without additional cost. The accuracy of the simplified SSM including the ESR zero of the output capacitor is verified by simulation software (PSIM). The design methodology of the 3ph-DAB converter and the performance of the proposed controller are verified by experimental results obtained with a 5-kW prototype 3ph-DAB converter.

• Nuclear Engineering and Technology
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• v.41 no.7
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• pp.893-906
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• 2009

The present work presents the development of a Large Eddy Simulation (LES) methodology viable for complex geometries and suitable for the simulation of rod-bundles. The use of LES and Direct Numerical Simulation (DNS) allows for a deeper analysis of the flow field and the use of stochastical tools in order to obtain additional insight into rod-bundle hydrodynamics. Moreover, traditional steady-state CFD simulations fail to accurately predict distributions of velocity and temperature in rod-bundles when the pitch (P) to diameter (D) ratio P/D is smaller than 1.1 for triangular lattices of cylindrical pins. This deficiency is considered to be due to the failure to predict large-scale coherent structures in the region of the gap. The main features of the code include multi-block capability and the use of the fractional step algorithm. As a Sub-Grid-Scale (SGS) model, a Dynamic Smagorinsky model has been used. The code has been tested on plane channel flow and the flow in annular ducts. The results are in excellent agreement with experiments and previous calculations.

• Journal of Distribution Science
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• v.20 no.8
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• pp.105-114
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• 2022

Purpose: The technology acceptance model (TAM) refers to a theory that maps the possibility or extent to which users can accept an innovative technology. The purpose of the current research is to investigate the mediating effect of TAM between online review and behavior intention for promoting golf app's distribution. Research design, data and methodology: In order to examine the relationship between app usage reviews, TAM, and behavioral intentions of golf app participants, the present author collected total 170 responses from South Korean participants based on web-based survey system. The main methodology which was selected by this study is mediation causality analysis that Baron and Kenny suggested. Results: The statistical findings definitely indicated that TAM mediating role exists between the positive emotion of golf app users regarding online reviews and positive behavior intention of golf app, which means that all three steps of mediation causality analysis were statistically significant. Conclusions: The present research concludes that the correct utilization of innovation in the design and implementation of the technology features translates into performance excellence. The model can be used to increase the online presence through innovation as a primary drive toward providing more convenience and accessibility to the users through mobile golf apps.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.68-72
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• 2005

Leuconostoc citreum is one of the representative strains of Leuconostoc spp. that show fast growth rates in fermented vegetables. Sequential experimental designs including the Plackett-Burman design, fractional factorial design, steepest ascent analysis, central composite design and response surface methodology were introduced tooptimize and improve the medium for Leuconostoc citreum. Fifteen medium ingredients were examined and glucose (20 g/l), yeast extract (12.5 g/l), sodium acetate trihydrate (6.12 g/l), potassium phosphate (42.55 g/l) and dibasic ammonium citrate (4.12 g/l)were chosen as the best components to give a critical and positive effect for cell-growth. The biomass was increased to 2.79 g/l (169%), compared to the 1.65 g/l in MRS medium.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.206-210
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• 2015

The most important thing for NOVEC gas fire extinguishing equipment is to release NOVEC gas, which contained in the extinguishing container, to the safety section by the time appointed. For this matter, it is significant to decide arrangement and size of the proper piping equipment. This study has developed the design methodology of NOVEC gas fire extinguishing equipment in use of pipe network analysis techniques. Based on the design methodology, each design coefficient is chosen. It is found that the calculated result, which is 6.498 seconds, has been counted within the 10 seconds limit, which is fairly satisfied with extinguishing releasing time based on the developed methodology. At that time, the pressure loss is 21.09bar.

• Asia-Pacific Journal of Business
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• v.13 no.3
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• pp.209-225
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• 2022

Purpose - The domestic technology trading market is composed of a technology trading platform with the participation of technology trading institutions. The institution that operates the technology trading platform provides various support for technology transaction. The purpose of this study is to suggest improvement plans through analysis of the services provided by the technology trading platform. Design/methodology/approach - TA model was built based on existing research and the importance and satisfaction of each evaluation item of the model were identified through the hierarchical analysis process and expert opinion gathering. Then importance-satisfaction correlation analysis was applied. Findings - As a result of analyzing the importance of the technology trading platform, supply technology information, technology value evaluation, and demand technology information are in order. Technology marketing and demand technology information are areas that require focus management and there are differences according to experience and low-skilled people suggest the need to improve technology value evaluation service. Research implications or Originality - This study is significant in that it evaluated the operational performance of a technology trading platform that had not been addressed for 15 years and suggested improvement measures. Initially a series of technology transaction processes such as technology value evaluation technology matching and technology commercialization support were expanded from simple information on previous technology and this study includes these changes.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1347-1356
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• 2024

Measuring the residual stress in the components in nuclear power plants is crucial to their safety evaluation. The instrumented indentation technique is a minimally invasive approach that can be conveniently used to determine the residual stress in structural materials in service. Because the indentation behavior of a structure with residual stresses is closely related to the elastic-plastic behavior of the indented material, an accurate understanding of the elastic-plastic behavior of the material is essential for evaluation of the residual stresses in the structures. However, due to the analytical problems associated with solving the elastic-plastic behavior, empirical equations with limited applicability have been used. In the present study, the impact of the non-equibiaxial residual stress state on indentation behavior was investigated using finite element analysis. In addition, a new nonequibiaxial residual-stress prediction methodology is proposed using a convolutional neural network, and the performance was validated. A more accurate residual-stress measurement will be possible by applying the proposed residual-stress prediction methodology in the future.

• Knowledge Management Research
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• v.8 no.1
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• pp.49-63
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• 2007

This paper presents a new methodology that allows the influence of technological obsolescence and technology composite competitiveness to estimate technology economic life. In this paper the patent citation life analysis is used to estimate technology representative life, and technology residual life analysis is employed to estimate residual life using the linear and inverse functions. The technology economic life will be determined by combining the estimation results of patent citation life analysis and technology residual life analysis. This paper includes an example of applying it to the US patent data for 5 communications areas. Therefore, this logical concept can be applied usefully to determine the technology economic life and be expected to contribute to obtain credibility of technology valuation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.1
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• pp.11-18
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• 2018

Two-dimensional (2D) materials such as transition metal dichalcogenides have attracted tremendous scientific interests owing to their potential of solving the zero band-gap issue of graphene. In this work, the research areas and technology evolutionary dynamics of the 2D materials were identified using the scientometric method focusing on keyword mapping and clustering. The time-series analysis showed that the technological progress of 2D material is in the early growth period. The overlay mapping analysis were carried out to investigate the technology evolution of 2D materials with time. The strategic diagram of co-word analysis classifying the topological positions of keyword was derived to support the analysis results. It is conjectured that extensive research will be conducted widely on the application of 2D materials not only in electronic and optoelectronic devices, but also in various other fields such as biomedical applications, and that their development will be more rapid based on accumulated results of extant graphene research.

• Journal of the Korean Society of Food Culture
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• v.38 no.2
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• pp.83-98
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• 2023

This study summarizes the research methods, subjects, research processes, and achievements of major researchers by analyzing previous research results on Korean food history. The goal of the current study aimed to seek the methodology and direction of 'food history research'. Literature data from 1945 to 2022 were examined. Results of excavation research on ancient food literature were divided into the following stages: the 1980s, when the foundation for 'cataloging' was laid, and the 2000s, when 'digitization' was achieved. Achievements of each period were collected, and the achievements and limitations were analyzed. Next, the research results were classified into 'Food technology history', 'Recipe change history', and 'Food culture and dietary history'. We observed that around the 2000s, anthropology and folklore research perspectives were reflected, and the research on 'history of diet' reached a turning point. Our results indicate the possibility that food history can develop as a special historical area. This could be achieved by establishing an exchange system with other disciplines and creating a systematic curriculum.