• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1674-1683
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• 2016

In this paper, a Finite Control Set Model Predictive Control (FCS-MPC) for a five level cascaded multilevel inverter (CMLI) with reduced switch topology is proposed. Five switches are used here instead of conventionally used eight switches. The main contribution of this paper is to make the MPC controller work for the reduced switch topology using only 19 voltage vectors in place of conventional 61 voltage vectors for a five level CMLI. This simplifies the execution of the MPC algorithm, paving a way for the significant reduction in the computational time. The controller makes use of the excellent ability of MPC to multitask, by adding one more objective which is to reduce the average switching frequency in addition to controlling the load current. This is especially important, since switching losses and therefore switching frequency is significant for high-power applications. The trade-off of this MPC is that the current is not as smooth as the 61 vector scheme, but well within the limits of IEEE standards. The results shown prove that this MPC works well in steady state and dynamic conditions too.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.3
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• pp.479-491
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• 1994

In this paper, we proposed cell priority control with 2-level thresholds, which was considered cell loss and cell delay requirement, in ATM switch with output buffer. Priority control mechanism presented in this paper improved cell loss rate for cell loss censitive cell and cell delay for delay censitive cell. In this mechanism cell loss rate and mean cell delay of cell priority control mechanism were obtained theoretically. The results show that cell loss rate and mean cell delay improvement become better by adjusting two thresholds according to QOS characteristics.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.318-321
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• 2002

A static var compensator using hybrid cascade 5-level PWM inverter is presented for high voltage/high power applications. The proposed system is modelled by circuit DQ transformation, and thus an equivalent circuit is obtained which reveals the important characteristics of the system and lead to the related equations. The proposed system has advantages of hybrid structure which enhances the better utilization of power semiconductor switches, that is, both high power-low frequency switch, GTO and low power-high frequency switch, IGBT can be used in the same circuit. In this paper, circuit structure and characteristics is presented and the validity of the characteristics analysis is shown through PSIM simulation.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1819-1829
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• 2018

A three-phase, three-switch, and three-level boost-type PWM rectifier (Vienna rectifier) is proposed as an active front-end power factor correction (PFC) rectifier for telecom loads. The proposed active front-end PFC rectifier system is modeled by the switching cycle average model. The relation between duty ratios and DC link capacitor voltages is derived in terms of the system input currents. Furthermore, the feasible switching states are identified and applied to the proposed system to reduce the switching stress and DC ripples. A detailed equivalent circuit analysis of the proposed front-end PFC rectifier is conducted, and its performance is verified through simulations in MATLAB. Simulation results are verified using an experimental setup of an active front-end PFC rectifier that was developed in the laboratory. Simulation and experimental results demonstrate the improved power quality parameters that are in accordance with the IEEE and IEC standards.

• Asia-Pacific Journal of Business
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• v.12 no.3
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• pp.193-212
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• 2021

Purpose - This study investigates the effect of auditor change on client firm's accounting (financial statement) comparability. Design/methodology/approach - The comparability of accounting information is measured by the difference in accruals between the two firms. Additionally, the study uses earnings-stock return relationship as another proxy of accounting comparability. In particular, the paper examines whether there is a systematic difference between initial audit years and the other years with respect to the client firm's accounting comparability. Moreover, current study tests how changes in auditor size or industry expertise before and after the switch of auditors affect the accounting comparability. Findings - The results show that the level of accounting comparability is lower in the year of auditor change than in the other years. Furthermore, this lower level of comparability is derived by the observations that switch their auditors from non-Big4 to non-Big4 or from non-specialist to non-specialist. These results are consistent when accounting comparability is measured by different proxies. Research implications or Originality - The findings of this study provide important policy implications for the regulations related with auditor selection.

• Journal of Internet of Things and Convergence
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• v.6 no.1
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• pp.97-102
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• 2020

Multi-Channel Switch ICs for IoT have integrated several solid state structure low ON-resistance bi-directional relay MOS switches with level shifter to drive high voltage and they should be independently controlled by external serialized logic control. These devices are designed for using in applications requiring high-voltage switching control by low-voltage control signals, such as medical ultra-sound imaging, ink-jet printer control, bare board open/short and leakage test system using Kelvin 4-terminal measurement method. This paper describes implementation of analog switch control block and its verification using Field programmable Gate Array (FPGA) test pattern generation. Each block has been implemented using Verilog hardware description language then simulated by Modelsim and prototyped in a FPGA board. Compare to conventional IC, The proposed architecture can be applied to fields where multiple entities need to be controlled simultaneously in the IoT environment and the proposed pattern generation method can be applied to test similar types of ICs.

• Journal of the Korea Society of Computer and Information
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• v.17 no.5
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• pp.147-155
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• 2012

Police education has shown a pronounced improvement during three eras in American police history. as the Reform Era arrived, the police academy was invented. With it, citizen expectations for the police expanded, and the level of competence exhibited by police grew. After the 1960s came the invention of the FTO and the creation of ongoing, in-service training requirements. in recent years, academics in many places-but by no means everywhere-are taking a more collegial approach to training, aimed especially at COP- style policing and the achievement of genuine professionalism. The Korean police training system is less efficient in education methodology, more inappropriate in the switch system of school education and practice, and poorer in educational environment, among others. Based on my findings, this paper recommends several improvement tips. First, legal stipulations on police training should be integrated and detailed. Second, active participation by preliminary police officers should be emphasized in the class of police training. Third, contents and hours for practice should be emphasized to maximize effects of the "switch system." Fourth, the educational environment of the Academy should be improved.

• The Korean Journal of Physiology and Pharmacology
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• v.26 no.5
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• pp.347-355
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• 2022

Abdominal aortic aneurysm (AAA) is a life-threatening disorder worldwide. Fibroblast growth factor 21 (FGF21) was shown to display a high level in the plasma of patients with AAA; however, its detailed functions underlying AAA pathogenesis are unclear. An in vitro AAA model was established in human aortic vascular smooth muscle cells (HASMCs) by angiotensin II (Ang-II) stimulation. Cell counting kit-8, wound healing, and Transwell assays were utilized for measuring cell proliferation and migration. RT-qPCR was used for detecting mRNA expression of FGF21 and activating transcription factor 4 (ATF4). Western blotting was utilized for assessing protein levels of FGF21, ATF4, and markers for the contractile phenotype of HASMCs. ChIP and luciferase reporter assays were implemented for identifying the binding relation between AFT4 and FGF21 promoters. FGF21 and ATF4 were both upregulated in Ang-II-treated HASMCs. Knocking down FGF21 attenuated Ang-II-induced proliferation, migration, and phenotype switch of HASMCs. ATF4 activated FGF21 transcription by binding to its promoter. FGF21 overexpression reversed AFT4 silencing-mediated inhibition of cell proliferation, migration, and phenotype switch. ATF4 transcriptionally upregulates FGF21 to promote the proliferation, migration, and phenotype switch of Ang-II-treated HASMCs.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.2
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• pp.120-126
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• 2006

A gate driver with Boot-strap chain is proposed to drive Multi-level PDP sustain switches. The proposed gate driver uses only one boot-strap capacitor and one diode per each MOSFETs switch without floating power supply. By adoption of this gate driver circuits, the size, weight and the cost of the driver board can be reduced.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.309-312
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• 2000

Single-phase multi-level AC-DC converter is proposed that is composed of diode bridge and switch. The number of the supply current level is depending on the individual current level of the converter. A converter circuit the number of the level is equal to $\textrm{2}^{M+1}$-1 The proposed circuit has converter with 31 current levels. When the number of current level is increased smoother sinusoidal waveform can be obtained directly and it is possible to control the supply current almost continuously from zero to maximum without step changes of generating high voltage as pulse width modulation switching loss is decreased it has an advantage in large capacity. it is illustrated technique are confirmed the validity and effectiveness through the simulation & experiments