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A Corpus Language Network Analysis of English Near-synonym Adjectives
Myoungho Ha 한국중원언어학회 2021 언어학연구 Vol.- No.61
This study aims to explore semantic similarities and differences among three near-synonym adjectives, and unveil semantic differences between BNC-based and COCA-based near-synonym adjectives. To achieve this goal, this study analyzes top 100 noun collocates of three near-synonym adjectives which are extracted from BNC and COCA respectively. And it also normalizes the frequency of noun collocates to correctly compare the data extracted from the differently-sized BNC and COCA. The analysis tools include Wmatrix 4 and NetMiner 4.0. Wmatrix 4 is a software tool for corpus analysis and comparison, and NetMiner 4.0 developed by Cyram is a network analysis software package, which performs an exploratory analysis. This study, in detail, analyzes both BNC-based and COCA-based semantic domains shared with all three near-synonym adjectives and ones exclusively shared with each near-synonym adjective. The result of this analysis shows that there are slight semantic differences among three near-synonym adjectives and distinct semantic differences in the real usages of each near-synonym adjective in the BNC-based and COCA-based authentic contexts.
Modeling and Controller Design for a SEries-Connected Output Universal Link Converter
Myoungho Kim,Seung-Ki Sul,Anno Yoo IEEE 2015 IEEE transactions on industry applications Vol.51 No.5
<P>This paper conducts modeling and controller design for a SEries-connected Output Universal Link (SEOUL) converter. The SEOUL converter was proposed to interface multiple distributed power sources to the grid with a reduced amount of reactive components. It employs a high-frequency (HF) transformer instead of a bulky line-frequency transformer like solid-state transformers (SSTs). In addition, it does not use a large dc-link capacitor at the input side and reduces the size of the input filter. This is inherently possible due to its original operating characteristic. The input phase current is not actively controlled but synthesized indirectly by HF power transfer between input and output sides of the SEOUL converter. Therefore, it is important to properly control the HF power transfer part, on which this paper focuses. An analytic model is developed, and a control strategy is proposed based on the model with a decoupling control method. The developed model and the proposed control method were verified by experiments.</P>
Compensation of Current Measurement Error for Current-Controlled PMSM Drives
Myoungho Kim,Seung-Ki Sul,Junggi Lee IEEE 2014 IEEE transactions on industry applications Vol.50 No.5
<P>Accurate measurement of phase current is crucial in a current-controlled permanent-magnet synchronous machine (PMSM) drive system. Current measurement error directly deteriorates torque control performance. This paper analyzes effects of the current measurement error on the phase current and the output voltage of the current controller. Based on the analysis, a compensation method is proposed. The proposed method compensates the offset and scaling errors separately without any additional hardware but using the commanded voltage reference of the current controller. The proposed method can be applied to general current-controlled PMSM drives in the whole operation range. Experimental results verify the effectiveness of the proposed compensation method.</P>
Exploring Academic Vocabulary in Advertising English Corpus
Myoungho Ha 한국중원언어학회 2020 언어학연구 Vol.0 No.57
This study analyzes GSL/AWL and NGSL/NAWL in Advertising English Corpus (AEC) and investigates the efficiency of GSL/AWL and NGSL/NAWL in terms of the distribution and coverage of word families. And it finally develops the Advertising English Academic Word List (AEAWL) that might be well suitable for vocabulary learning and teaching tools in the education settings. For these goals, this study constructed AEC that contains about 3 million running words. The AEC was compiled from three registers such as 131 articles, 30 dissertations, and 10 textbooks as the target corpus. This study has developed a total of 1,417 AEAWL that was extracted from GSL and AWL on the basis of Coxhead’s (2000) three selection criteria: specialized occurrence, range, and frequency. In addition, the study developed a total of 1,358 AENAWL of NGSL plus NAWL. The findings fully confirmed that GSL and AWL were better optimized than NGSL and NAWL in terms of the efficiency. Developing more technical vocabulary remains for further research.
A Dual-Phase-Shift Control Strategy for Dual-Active-Bridge DC-DC Converter in Wide Voltage Range
Myoungho Kim,Martin Rosekeit,Seung-Ki Sul,Rik W. A. A. De Doncker 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper analyzes the dual-phase-shift (DPS) control strategy for a dual-active-bridge (DAB) converter in whole operation range. The DPS has two degree of freedom to control the transferring power, which can improve the performance of the DAB converter than single-phase-shift (SPS) control strategy. This paper derives the reactive power, the rms and the peak current flowing on the transformer and the zero-voltage-switching (ZVS) condition according to the operating conditions. Using this analysis and simulation results, a suitable control strategy for DAB converter is obtained. Experiments are performed to verify the proposed control strategy and to compare with the conventional SPS control strategy. The experimental results show that the proposed method can enhance the overall efficiency and expand the ZVS operation range.
MyoungHo Kim,Sung-Uk Lee 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.7
The desired performance of nonlinear systems by using only proportional-integral-derivative (PID) controllers is difficult to obtain because of its simple structure. To improve the control performance of nonlinear systems, we proposed a PID with a switching action (PIDSA) controller that only adds the switching action of a sliding mode control (SMC) while maintaining the structure of the PID. The PIDSA controller has the simplicity of PID and the robustness of SMC. In addition, a double integral sliding surface (DISS) was designed to match the characteristics of the PID with the switching action. The stability of the overall system was proved for nonlinear systems by performing the Lyapunov stability analysis. Finally, experiments were conducted on a hydraulic manipulator, which is a highly nonlinear system. The results show that the proposed controller exhibits excellent performance and that DISS enhances the performance compared with using an integral sliding surface.