• 한국안전학회지
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• 제12권1호
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• pp.29-36
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• 1997

Precision electronic equipments for outdoor use are composed of sophisticated microcircuits that are extremely vulnerable to lightning-caused voltage spike. This transient voltage spike may cause upset, latent failure or Interference on electronic equipments. In order to develop efficient lightning protection measures on AC power lines of a road traffic controller as a electronic equipment for outdoor use, experimental surge immunity tests were conducted according to IEC standard 801-5. The combination of gas tube arrester and metal-oxide varistor was installed at the input of AC power lines and the silicon avalanche suppressor installed at the output of DC power supply for the lightning protection measures.

• 한국전자파학회논문지
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• 제14권4호
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• pp.336-342
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• 2003

본 논문에서는 잡음광의 영향이 심한 환경에서 솔라 셀을 이용하여 잡음광에 의한 저주파 간섭을 소거하는 동시에 강한 잡음광을 수신부의 전원으로 활용할 수 있는 차동검출기를 새로이 소개한다. 솔라 셀에서 검출되는 DC전압을 수신부의 전원으로 사용하고, AC전압을 이용하여 차동검출방식으로 포토다이오드의 잡음전압을 소거함으로써 신호대잡음비가 약 20 dB 개선되었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.438-441
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• 2001

Nonlinear loads change the sinusoidal nature of the ac power current, thereby resulting in the flow of harmonic currents in the ac power system that can cause interference with communication circuits and other type of equipment. To minimize the damage, it is needed to limit harmonics current and voltage. Harmonic measurement system was developed to measure individual voltage and current harmonic continuously and save harmonic data on computer. We measured all 154kV feeders in a steel making company substation. Voltage and current distortion limits for general transmission systems was suggested We found some feeders exceeded current distortion limits. As result voltage harmonic exceeded standard limits.

• 전력전자학회논문지
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• 제20권3호
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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.

• Journal of Power Electronics
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• 제18권3호
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• pp.923-930
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• 2018

Based on the application of an integrated dynamic brake (IDB) system that uses a PWM inverter fed-AC motor drive to operate the piston, a new active zero state PWM (AZSPWM) is proposed to improve the stability and reliability of the IDB system by suppressing the conducted electro-magnetic interference (EMI) noise under a wide range of load torque. The new AZSPWM reduces common-mode voltage (CMV) by one-third when compared to that of the conventional space vector PWM (CSVPWM). Although this method slightly increases the output current ripple by reducing the CMV, like the CSVPWM, it can be used within the full range of the load torque. Further, unlike other reduced common-mode voltage (RCMV) PWMs, it does not increase the switching power loss. A theoretical analysis is presented and experiments are performed to demonstrate the effectiveness of this method.

• 대한전자공학회논문지TC
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• 제39권12호
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• pp.539-546
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• 2002

본 논문에서의 패킷 스케줄러는 무선 채널 환경에서 실시간 비디오 트래픽과 비실시간 인터넷 트래픽을 동시에 서비스한다. 그리고 실시간 트래픽에 대한 지연을 감소 시기키 위하여 누적카운터와 SIR값을 동시에 고려하는 새로운 패킷 스케줄링 알고리즘을 제안한다. 본 알고리즘에서는 실시간 트래픽을 비실시간 트래픽에 비하여 우선적으로 처리한다. 시뮬레이션 결과를 고찰할 때, 실시간 비디오 트래픽과 같이 지연성능에 민감한 서비스의 경우에는 AC(Accumulation Counter) 방식이 기존의 M-LWDF방식보다 더 적합한 알고리즘으로 관찰되었다. 본 논문에서는 HSDPA 시스템과 유사한 구조를 채택하여 시간 축으로는 프레임 주기를 가지며 동시에 코드 축으로는 OVSF 코드를 사용할 수 있는 구조를 채택하여 모의 실험을 수행하였다.

• The Korean Journal of Physiology and Pharmacology
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• 제21권4호
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• pp.397-405
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• 2017

MDL-12330A is a widely used adenylyl cyclase (AC) inhibitor that blocks AC/cAMP signaling. In this study, we demonstrated a novel antitumor activity of this drug in gastric carcinoma (GC) cell lines. In these GC cells, MDL-12330A reduced cell viability and induced cell death in a concentration-dependent manner. At a moderate concentration (${\sim}20{\mu}M$), MDL-12330A mainly induced apoptotic death whereas at concentrations greater than $20{\mu}M$, it increased non-apoptotic cell death. The induction of apoptosis was at least partially regulated by CHOP-mediated DR5 upregulation, as detected by immunoblotting and gene interference assays. More importantly, low concentrations of MDL-12330A effectively enhanced recombinant human tumor necrosis factor (TNF)-related apoptosis-inducing ligand (rhTRAIL)-induced apoptosis and clonogenicity in these gastric cancer cells. This study demonstrates a possible role of MDL-12330A as a potential sensitizer to TRAIL, and suggests a novel therapeutic strategy targeting gastric cancer cells.

• 전력전자학회논문지
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• 제22권4호
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• pp.277-284
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• 2017

For passive power factor correction, the valley fill circuit approach is attractive for low power applications because of low cost, high efficiency, and simple circuit design. However, to vouch for the product quality, two dc-link capacitors in the valley fill circuit should be selected to withstand the peak rectified ac input voltage. The common mode (CM) and differential mode (DM) choke should be used to suppress the electromagnetic interference (EMI) noise, thereby resulting in large size volume product. This paper presents the practical design and implementation of a valley fill flyback converter with reduced dc link capacitors and EMI magnetic volumes. By using the proposed over voltage protection circuit, dc-link capacitors in the valley fill circuit can be selected to withstand half the peak rectified ac input voltage, and the proposed CM/DM choke can be successfully adopted. The proposed circuit effectiveness is shown by simulation and experimentally verified by a 78W prototype.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.908-910
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• 1998

Modern AC electric car has PWM(Pulse Width Modulation) -controlled converters, which give rise to higher harmonics. The current harmonics injected from AC electric car is propagated through power feeding circuit. As the feeding circuit is a distributed constant circuit composed of RLC, the capacitance of the feeding circuit and the inductance on the side of power system cause a parallel resonance and a magnification of current harmonics at a specific frequency. The magnified current harmonics usually brings about various problems. That is, the current harmonics makes interference in the adjacent lines of communications and the railway signalling system. Furthermore, in case it flows on the side of power system, not only overheating and vibration at the power capacitors but also wrong operation at the protective devices can occur. Therefore, the exact assessment of the harmonic current flow must be undertaken at design and planning stage for the electric traction systems. From these point of view, this study presents an approach to model and to analyse traction power feeding system focused on the amplification of harmonic current. The proposed algorithm is applied to a standard AT(Auto-transformer)-fed test system in which electric car with PWM-controlled converters is running.

• Bulletin of the Korean Chemical Society
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• 제34권1호
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• pp.99-106
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• 2013

Polyaniline-yttrium trioxide (PAni-$Y_2O_3$) composites were synthesized by the in-situ polymerization of aniline in the presence of $Y_2O_3$ The composite formation and structural changes in these composites were investigated by X-ray diffraction (XRD), Fourier transform infra red spectroscopy (FTIR), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The direct current (DC) electrical conductivity of the order of $0.51{\times}10^{-2}\;S\;cm^{-1}-0.283\;S\;cm^{-1}$ in the temperature range 300 K-473 K indicates semiconducting behavior of the composites. Room temperature AC conductivity and dielectric response of the composites were studied in the frequency range of 10 Hz to 1 MHz. The variation of AC conductivity with frequency obeyed the power law, which decreased with increasing weight percentage (wt %) of $Y_2O_3$. Studies on dielectric properties shows the relaxation contribution coupled by electrode polarization effect. The dielectric constant and dielectric loss in these composites depend on the content of $Y_2O_3$ with a percolation threshold at 20 wt % of $Y_2O_3$ in PAni. Electromagnetic interference shielding effectiveness (EMI SE) of the composites in the frequency range 100 Hz to 2 GHz was in the practically useful range of -12.2 dB to -17.2 dB. The observed electrical and shielding properties were attributed to the interaction of $Y_2O_3$ particles with the PAni molecular chains.