• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.1
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• pp.1-10
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• 2016

Drivers for LED MR16 retrofit lamps need to be compatible with the dimmers and electronic transformers which originally operated with the halogen lamps to be replaced. We present a two-stage MR16 LED driver consisting of a boost converter in the first stage and a buck converter in the second stage. Our design has been analyzed in the frequency domain using simulations to demonstrate that it effectively suppresses the high-frequency components of the AC output of the electronic transformer. Experiment results with a driver prototype verify the simulation results as well as dimmability.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.4
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• pp.885-891
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• 2011

In this paper, we studied dc leakage current properties analysis of LED lamps of road and landscape lighting when leakage current appeared in dc power line. Generally, converter of LED lighting is divides to insulated type and non-insulated type according to components. When electric leakage happened in AC power line, earth leakage breaker(ELB) senses leakage current and interrupts electric circuit. In dc power source, We need experimental verification about dc electric leakage for electricity safety. In normal wiring conditions and in the water, in case of using insulated type of converter, dc leakage current did not occur. However, in case of using non-insulated type of converter, dc leakage current occurred and passed through into the ground. We found that there is a hazard of electric shock by dc leakage current. We expect that the results of these studies would be helpful for electrical safety of LED lamps for road and landscape lighting.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.92-93
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• 2019

항로표지 사용하는 육지초인용 전구식 대형 등명기의 메탈할라이드 램프는 수명이 1,000시간으로 LED 광원과 비교하여 매우 짧은 수명으로 유지관리에 어려움이 발생하고 있으며 전구식 회전형 대형 등명기는 고압방전등 및 AC 모터를 사용하고 있어 고장 발생 빈도가 높고 긴급수리에 장시간이 소용되어 기능 유지가 어려운 실정이다. 본 연구에서는 회전형 대형등명기의 렌즈를 사용하고 자동절환이 가능한 광원부 기구 개선 및 광원을 고출력 LED로 대체하고 기존 회전형 대형등명기의 렌즈에 적합한 고효율 LED 반사판을 설계·제작하여 광학특성을 측정하고 분석하였다. 또한 광학특성에 적합한 연안등대에 시범설치를 통하여 성능 검증 및 운영 개선을 통한 실용화 연구를 수행하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.3
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• pp.262-272
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• 2015

An integrated two-in-one transformer applicable to PSUs for a 120 W LED TV is proposed. This transformer comprises a PFC inductor and an LLC transformer placed and integrated on an E-I-E type magnetic core. Performance is evaluated by observing the coupling coefficients of the proposed two-in-one transformer under various air gap topologies. Among the topologies studied, an integrated transformer with centered air gap shows stable operational characteristics with a minimized mutual coupling (interference). Furthermore, applicability of the proposed integrated transformer to PSUs for a 120 W LED TV is studied from the viewpoint of integrating different magnetic components into one core, resulting to low weight, low cost, and high power density.

• Biomolecules & Therapeutics
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• v.22 no.6
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• pp.525-531
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• 2014

In the present study, we investigated whether apigenin significantly affects tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$)-induced production and gene expression of MUC5AC mucin in airway epithelial cells. Confluent NCI-H292 cells were pretreated with apigenin for 30 min and then stimulated with TNF-${\alpha}$ for 24 h or the indicated periods. The MUC5AC mucin gene expression and mucin protein production were measured by reverse transcription - polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Apigenin significantly inhibited MUC5AC mucin production and down-regulated MUC5AC gene expression induced by TNF-${\alpha}$ in NCI-H292 cells. To elucidate the action mechanism of apigenin, effect of apigenin on TNF-${\alpha}$-induced nuclear factor kappa B (NF-${\kappa}B$) signaling pathway was also investigated by western blot analysis. Apigenin inhibited NF-${\kappa}B$ activation induced by TNF-${\alpha}$. Inhibition of inhibitory kappa B kinase (IKK) by apigenin led to the suppression of inhibitory kappa B alpha ($I{\kappa}B{\alpha}$) phosphorylation and degradation, p65 nuclear translocation. This, in turn, led to the down-regulation of MUC5AC protein production in NCI-H292 cells. Apigenin also has an influence on upstream signaling of IKK because it inhibited the expression of adaptor protein, receptor interacting protein 1 (RIP1). These results suggest that apigenin can regulate the production and gene expression of mucin through regulating NF-${\kappa}B$ signaling pathway in airway epithelial cells.

• Information Display
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• v.21 no.2
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• pp.16-24
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• 2020

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.4
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• pp.4-12
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• 2013

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.2
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• pp.72-75
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• 2011

In this paper, the voltage across the LED system supplied by positive voltage of power supply system the power consumption of the LED itself, and uses a lot of transformers and analog devices, such as converter startup problems and constant temperature even when the voltage driving abnormally LED current in the destruction caused by the flow of a lot of problems can occur. In this paper, we obtain the technology of consistent current using PWM(pulse width modulation) mode in order to minimize analog devices and eventually discuss the technology to develop consistent output converter using power drive IC.

• Journal of Power Electronics
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• v.13 no.4
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• pp.609-618
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• 2013

This paper proposes a primary side constant power control scheme for TRIAC dimmer compatible LED drivers. The LED driver is a Flyback converter operated in boundary conduction mode (BCM) to minimize the switching loss. With the proposed control scheme, the input power of the Flyback converter can be controlled by the TRIAC dimming angle, which is not affected by AC input voltage variations. Since the output voltage is almost constant for LED loads, the output current can be changed by controlling the input power with a given conversion efficiency. The isolated feedback circuit is eliminated with the proposed primary side control scheme, which dramatically simplifies the whole circuit. In addition, the input current automatically follows the input voltage due to the BCM operation, and the resistive input characteristic can be achieved which is attractive for TRIAC dimming applications. Experimental results from a 15W prototype verify the theoretical analysis.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.914-919
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• 1998

A Capacitor Commutated Converter (CCC) has less difficulty of commutation failure in comparison to the conventional line commutated converter. This paper proposes the Ar1R control of the CCC in the inverter operation, which deserves as the Ar1R of the conventional converter. The CCC can be operated in high power factor area by using the proposing Ar1R control. The voltage stability at an AC bus connected the CCC inverter is investigated and estimated its ability of preventing the AC voltage collapse. To estimate the voltage stability, this paper developed the simplified converter mathematical model and led the VSF index. The results shows that the AC voltage stability is guaranteed and enables the interconnection to an weak AC system, when compensation factor of the compensation capacitor is higher than 200%.