• ETRI Journal
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• v.43 no.5
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• pp.891-899
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• 2021

We propose a stray inductance extraction method on power modules of the few-kilovolts/several-hundred-amperes class using only low voltages and low currents. The method incorporates a double-pulse generator, a level shifter, a switching device, and a load inductor. The conventional approach generally requires a high voltage of more than half the power module's rated voltage and a high current of around half the rated current. In contrast, the proposed method requires a low voltage and low current environment regardless of the power module's rated voltage because the module is measured in a turn-off state. Both theoretical and experimental results are provided. A physical circuit board was fabricated, and the method was applied to three commercial power modules with EconoDUAL3 cases. The obtained stray inductance values differed from the manufacturer-provided values by less than 1.65 nH, thus demonstrating the method's accuracy. The greatest advantage of the proposed approach is that high voltages or high currents are not required.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.5
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• pp.398-412
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• 2023

The Korean government is actively promoting the hydrogen industry as a key driver of economic growth. This commitment is evident in the 2019 hydrogen economy activation roadmap and the 2021 basic plan for hydrogen economy implementation. This study quantitatively analyzes the economic impact of the hydrogen economy using input-output analysis based on the Bank of Korea's 2019 input-output table, projecting its size by 2050. Four parts dealt with production-inducing, value-added creation, employment-inducing, and wage-inducing based on a demand-driven model. The results reveal that transportation had the most remarkable economic effect throughout the hydrogen economy, and production was the least. The hydrogen economy is projected to reach 71.2 trillion won by 2050.

• Journal of Industrial Convergence
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• v.19 no.5
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• pp.1-11
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• 2021

Prior research regarding the macro patterns of industry convergence has focused on the inter-industry patent network and cross-industry movements of products or services. This article provides a novel approach, according to which human resources embodying explicit and implicit knowledge and technologies are important media driving industry convergence. Drawing on GOMS data (2015-2019) and using information of university graduates' academic majors and their occupations, this article proposes an analytic strategy by which to understand the macro patterns and structural features of industry convergence. Specifically, we build unbalanced bipartite networks of major-industry (occupation) relations, and construct the measures of the industry's niche width and the measure of the average degree of convergence of majors that each industry is linked to. By crossing the two measures, we identify four groups of industries(occupations); specialist, generalist, partial convergence, and full convergence. The convergence group is composed of industries (occupations) that acquire human resources from a number of academic majors each of which plays a role of glue connecting several local industries.

• Journal of Ocean Engineering and Technology
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• v.17 no.6
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• pp.38-46
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• 2003

Aim of this article is to propose Micro-Genetic Simulated Annealing (${\mu}GSA$) as a hybrid metaheuristics approach to find the global optimum of nonlinear optimisation problems. This approach combines the features of modern metaheuristics such as micro-genetic algorithm (${\mu}GAs$) and simulated annealing (SA) with the general robustness of parallel exploration and asymptotic convergence, respectively. Therefore, ${\mu}GSA$ approach can help in avoiding the premature convergence and can search for better global solution, because of its wide spread applicability, global perspective and inherent parallelism. For the superior performance of the ${\mu}GSA$, the five well-know benchmark test functions that were tested and compared with the two global optimisation approaches: scatter search (SS) and hybrid scatter genetic tabu (HSGT) approach. A practical application to structural sandwich panel is also examined by optimism the weight function. From the simulation results, it has been concluded that the proposed ${\mu}GSA$ approach is an effective optimisation tool for soloing continuous nonlinear global optimisation problems in suitable computational time frame.

• Journal of information and communication convergence engineering
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• v.10 no.2
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• pp.141-148
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• 2012

This paper presents a simple but efficient scheme incorporating a reputation-based approach and a cross-layer approach, called the SIM scheme, for maintaining reliable connectivity and high performance in ad-hoc wireless networks. The SIM scheme incorporates the following two things: an ad-hoc routing scheme with a reputation-based approach exploiting the game theory concept based on an evolutionarily stable strategy, and a cross-layer approach between the network layer and the transport layer employing a reputation-based approach.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.440-440
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• 2012

Nanomaterials have emerged as new building blocks to construct light energy harvesting assemblies. Size dependent properties provide the basis for developing new and effective systems with semiconductor nanoparticles, quantized charging effects in metal nanoparticle or their combinations in 2 and 3 dimensions for expanding the possibility of developing new strategies for photovoltaic system. As top-down approach, we developed a simple and effective method for the large scale formation of self-assembled Cu(In,Ga)$Se_2$ (CIGS) nanostructures by ion beam irradiation. The compositional changes and morphological evolution were observed as a function of the irradiation time. As the ion irradiation time increased, the nano-dots were transformed into a nano-ridge structure due to the difference in the sputtering yields and diffusion rates of each element and the competition between sputtering and diffusion processes during irradiation. As bottom-up approach, we developed the growth of CIGS nanowires using thermal-chemical vapor deposition (CVD) method. Vapor-phase synthesis is probably the most extensively explored approach to the formation of 1D nanostructures such as whiskers, nanorods, and nanowires. However, unlike binary or ternary chalcogenides, the synthesis of quaternary CIGS nanostructures is challenging because of the difficulty in controlling the stoichiometry and phase structure. We introduced a method for synthesis of the single crystalline CIGS nanowires in the form of chalcopyrite using thermal-CVD without catalyst. It was confirmed that the CIGS nanowires are epitaxially grown on a sapphire substrate, having a length ranged from 3 to 100 micrometers and a diameter from 30 to 500 nm.

• Journal of Digital Convergence
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• v.15 no.2
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• pp.233-238
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• 2017

The purpose of this study is to investigate the necessity of policy approach in terms of complex combination of tourists and fishing villages. In order to achieve the purpose of this study, the policies related to the marine tourism industry were investigated and the laws related to the development of the coastal area and fishing port area were investigated. As a convergence approach to marine tourism policy, First, the development of marine tourism resources should be based on the increase of hydrophilic activities and the characteristics of the four seasons. In particular, the need to dig through support of projects such as the successful model that made aquarium associations etc. that are currently in progress, such as "fishing village experience".

• Journal of the Korea Convergence Society
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• v.13 no.5
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• pp.53-60
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• 2022

The purpose of this study is to identify the causal relationship of the structural model through approach motivation, avoidance motivation, and digital usage recognition in order to prepare a plan for coexistence with dental hygiene targeting 239 students from the dental hygiene department at a university in Gangwon-do. For statistical methods, SPSS Statistics 24.0 program and AMOS 21.0 were used. As a result of the structural equation model analysis, the motivation for approach was found to be significantly related to digital usage recognition and class satisfaction. In addition, digital usage perception was found to be significantly related to class satisfaction, and class satisfaction was shown to be significantly related to department satisfaction and department recommendation. Lastly, department satisfaction was significantly found in department recommendation. In other words, the coexistence plan with dental hygiene (department) is to expand the convergence of digital classes. In order to solve the problem, it is necessary for schools to establish facilities to expand teaching materials for practical classes and to devise teaching methods.

• Journal of applied mathematics & informatics
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• v.30 no.3_4
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• pp.365-380
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• 2012

Non-negative matrix factorization (NMF) is a very efficient method to explain the relationship between functions for finding basis information of multivariate nonnegative data. The multiplicative update (MU) algorithm is a popular approach to solve the NMF problem, but it fails to approach a stationary point and has inner iteration and zero divisor. So the elementwisely alternating projected gradient (eAPG) algorithm was proposed to overcome the defects. In this paper, we use the fact that the equilibrium point is stable to prove the convergence of the eAPG algorithm. By using a classic model, the equilibrium point is obtained and the invariant sets are constructed to guarantee the integrity of the stability. Finally, the convergence conditions of the eAPG algorithm are obtained, which can accelerate the convergence. In addition, the conditions, which satisfy that the non-zero equilibrium point exists and is stable, can cause that the algorithm converges to different values. Both of them are confirmed in the experiments. And we give the mathematical proof that the eAPG algorithm can reach the appointed precision at the least iterations compared to the MU algorithm. Thus, we theoretically illustrate the advantages of the eAPG algorithm.

• ETRI Journal
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• v.36 no.6
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• pp.1051-1061
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• 2014

Technological advances made with the development of digital technology and the Internet have led to the emergence and evolution of digital convergence - the integration of media and communications. This, in turn, has led to the creation of the representative broadcast and communication convergence business model (IPTV service). This study examines the consumption patterns and behaviors of IPTV service customers and explores the process of their continuous use of the IPTV service, thereby endeavoring to contribute to the diffusion of digital convergence services. To survey customers' continuous use of the IPTV service, this study first designs a research framework based on an examination of the existing literature on satisfaction, loyalty, and so on. In addition, research is conducted on the switching barrier of the method of consolidating customers' adherence to a given IPTV service by increasing the burden on them, thereby developing a final research model with which to attempt yet another heterogeneous approach. This enables not only an analysis of the causal relationship with antecedent variables but also a measurement of the explanatory contribution of the antecedent variables' sub-variables.