• Journal of Power Electronics
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• v.10 no.2
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• pp.132-137
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• 2010

Interleaving techniques are widely used to reduce input/output ripples and to increase the power capacity of boost converters operating in critical conduction mode. Two types of phase-shift control schemes are studied in this paper, the turn-on time shifting method and the turn-off time shifting method. It is found that although the turn-off time shifting method exhibits better performance, it suffers from sub-harmonic oscillations at high input voltages. To solve this problem, an intensive quantitative analysis of the sub-harmonic oscillation phenomenon is made in this paper. Based upon that, a novel modified turn off time shifting control scheme for interleaved boost converters operating in critical conduction mode is proposed. An important advantage of this scheme is that both the master phase and the slave phase can operate stably in critical conduction mode without any oscillations in the full input voltage range. This method is implemented with a FPGA based digital PWM control platform, and tests were carried out on a two-phase interleaved boost PFC converter prototype. Experimental results demonstrated the feasibility and performance of the proposed phase-shift control scheme.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.5
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• pp.458-465
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• 2013

This paper proposes a novel soft-switched auxiliary resonant circuit to provide a Zero-Voltage-Transition at turn-on for a conventional PWM boost converter in a PFC application. The proposed auxiliary circuit enables a main switch of the boost converter to turn on under a zero voltage switching condition and simultaneously achieves both soft-switched turn-on and turn-off. Moreover, for the purpose of an intelligent multi-chip power module fabrication, the proposed circuit is designed to satisfy several design constraints including space saving, low cost, and easy fabrication. As a result, the circuit is easily realized by a low rated MOSFET and a small inductor. Detail operation and the circuit waveform are theoretically explained and then simulation and experimental results are provided based on a 1.8 kW prototype PFC converter in order to verify the effectiveness of the proposed circuit.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.720-722
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• 2003

This paper Presents a design schemes to minimize torque ripple in 6/4 Switched Reluctance Motor (SRM) using transient Finite Element Analysis (FEA) in which the magnetic field is combined with a driving circuit. Pole arcs and switching angles are major design factors. If these design factors are considered independently, the enhancement of SRM Performance is restricted. Therefore, this paper proposes not only optimal combination of stator pole arc and rotor pole arc but also the turn-on and turn-off angles as a function of pole arcs. Especially, turn-on and turn-off angle are formulated from a voltage equation and feasible design ranges are suggested with variable speed.

• Transactions of Materials Processing
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• v.14 no.6 s.78
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• pp.533-540
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• 2005

The hemming process, composed of flanging, pre-hemming and main hemming, is the last one of a series of forming processes conducted on the automotive panels, having greater influence on the outward appearance of cars rather than on their performance. The hem quality can be quantitatively defined by the hemming defects including turn-down/up, warp and roll-in/out. However, it is difficult to evaluate and predict the hem quality through an experimental measurement or a numerical calculation since the size of defects is very small. This study aims to precisely evaluate the hemming defects, especially turn-down and roll-in, through numerical and experimental approaches and to investigate the influence of process parameters on the hem quality, focused on how to simulate the same conditions as in the experiment by the finite element analysis (FEA). The FEA results on the turn-down and roll-in obtained from a model composed of the optimum-sized elements, including a spring element linked to the flanging pad, and given the double master contact condition between the inner and outer panels, had a good correlation with the experimental data. It is thought possible to make an early estimate of the hem quality in a practical automotive design by applying the methodology proposed in this study.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1445-1453
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• 2017

In this study, a new zero-voltage transition (ZVT) buck converter with coupled inductor using a synchronous rectifier and a lossless clamp circuit is proposed. The regular buck converter with tapped inductor has extended duty cycle for high step-down applications. However, the leakage inductance of the coupled inductor produced considerable voltage spikes across the switch. A lossless clamp circuit is used in the proposed converter to overcome this problem. The freewheeling diode was replaced with a synchronous rectifier to reduce conduction losses in the proposed converter. ZVT conditions at turn-on and turn-off instants were provided for the main switch. The synchronous rectifier switch turned on under zero-voltage switching, and the auxiliary switch turn-on and turn-off were under zero-current condition. Experimental results of a 100 W-100 kHz prototype are provided to justify the validity of the theoretical analysis. Moreover, the conducted electromagnetic interference of the proposed converter is measured and compared with its hard-switching counterpart.

• The Journal of the Korea Contents Association
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• v.22 no.3
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• pp.413-429
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• 2022

"Tourist Gaze" discussion in the 21st century introduces that tourist is the post-modern and post-fordism figure. Festival visitors can be said as one of the post-modern tourists, so this figure has "performance turn" feature as well. It will be discussed here why festival visitors of the Edinburgh Fringe Festival want to visit the festival. As post-modern and post-fordism figure, festival visitors want to experience autonomy, competence and relationshjp based on the performance turn.

• Journal of Environmental Science International
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• v.32 no.11
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• pp.757-765
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• 2023

Lead, a heavy metal widely employed in various industries, continues to pose a threat to both human health and the environment. Therefore, the development of a sensor capable of rapidly and accurately detecting lead(II) ions in real-time at contaminated sites is crucial. In this study, we have engineered a fluorescent sensor with the ability to efficiently detect lead(II) ions under actual environmental conditions, including tap water and freshwater. The compound, tetraphenylethylene carboxylic acid derivative (TPE-COOH), exhibits high selectivity and sensitivity toward lead(II) ions in aqueous solution, where the interaction between TPE-COOH and lead(II) ions leads to its aggregation, thus triggering a fluorescence "turn-on" based on the aggregation-induced emission (AIE) mechanism. Impressively, compound TPE-COOH proficiently detects lead(II) ions within a range of 30 to 100 𝜇M in tap water and freshwater, even in the presence of various interfering substances.

• SUVANNABHUMI
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• v.16 no.1
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• pp.15-38
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• 2024

In this paper, I will pursue initial ideas I formulated in 2012 about the permeation of Korean influences in Philippine popular culture, particularly in the production of serialized TV drama/soap operas or the "teleserye" [tele for television + "serye" or series; thus, TV drama series]. I called the phenomenon the "Korean Turn" as I observed the emulation of Korean televisual drama (nowadays called K-Drama) modes and practices by local production through various means of cultural appropriation. This time, I will expand my exploration to other aspects of Philippine entertainment and other cultural practices. I will also update my observations on the continuing "Korean turn" in the teleserye. I will argue, on the one hand, about the success and soft power of hallyu or the "Korean wave" in the Philippines; and on the other, about Philippine culture's enduring ingenuity in its reception and repurposing of hallyu. Ideas to be yielded here will form part of a potential framework in understanding the dynamics of the interface between Korean and Philippine cultures, in the context of globalization. I assert that popular culture remains to be an undervalued field of inquiry, as far as these contexts are concerned.

• Journal of Engineering Education Research
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• v.9 no.4
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• pp.5-9
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• 2006

In this research, a case study for cooperative learning practiced in a design class for environmental engineering was presented. Designing a treatment facility for urban diffuse pollution was a main problem given to the participants. Turn-key system for civil works were simulated throughout class works. Twenty five students were grouped into four virtual companies and assigned own position from chairperson to workers. Each group competed throughout establishing design concept regarding order, expense calculation, process distribution, actual calculation. Best design with lowest bidding won the first place. For evaluating class effectiveness, one student from each group were monitored thorough semester. Participants were improved for their understanding about company establishment, turn-key system management, awareness about personal management, and presentation skills. Tension of the class was effectively elevated as well.

• Journal of Korea Multimedia Society
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• v.7 no.3
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• pp.377-387
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• 2004

This paper describes a tree-based conversational interface supporting efficient presentation of turn relations on online conversation. Most of conventional conversational interfaces are difficult to make use of formal conversation such as group meeting, decision-making, etc. due to very simplicity of a con versational interface and restriction of data structure of conversational messages. And a tree-based conversational interface supports formal conversation, but they are difficult to present turn relations because of jumpy display by locations of replied turns and distance between replied turns, etc. So this paper suggests a tree-based conversational interface to present efficiently turn relations using XML-based messages with merits of a text-based interface. The suggested conversational interface was implemented by using XML-, DOM, and JDK. And this paper showed that the conversational interface could be applied to conversation system using client- server architecture. Applications for the conversational interface are as follows: collaboration, distance teaming, online game, etc.