• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권1호
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• pp.23-29
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• 2005

This paper presents the characteristics of leakage currents flowing through ZinC Oxide(ZnO) surge arrester blocks under mixed direct and 60 Hz alternating voltages. A mixed voltage, in which an alternating voltage is superimposed upon a direct voltage, appears on the HVDC system network. The mixed direct and alternating voltage generator with a peak open-circuit of 10 kV was designed and fabricated. The leakage currents and V-I curves for the fine and used ZnO surge arrester blocks were measured as a function of the voltage ratio k, where the voltage ratio k is defined as the ratio of the peak of alternating voltage to the peak of the mixed voltages. The resistive component in the leakage current in the low conduction region is significantly increased with increasing the voltage ratio k. The V-I characteristic curves for the mixed voltages lies between the direct and alternating characteristics, and the cross-over phenomenon in the high conduction region was appeared.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 추계종합학술대회
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• pp.494-497
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• 2002

본 논문에서는 halo doping profile을 갖는 나노구조 LDD MOSFET의 문턱전압에 대한 시뮬레이션 결과를 나타내었다. 소자 크기는 generalized scaling을 사용하여 100nm에서 40nm까지 스케일링하였다. Van Dort Quantum Correction Model(QM)을 사용하여 정전계 스케일링과 정전압 스케일링에 대한 문턱 전압과 각각의 게이트 oxide 두께에 대한 direct tunneling 전류를 조사하였다. 게이트 길이가 감소할 때 정전계 스케일링에서는 문턱전압이 감소하고, 정전압 스케일링에서는 문턱전압이 증가하는 것을 알 수 있었고, 게이트 oxide두께가 감소할 때 direct tunneling 전류는 증가함을 알 수 있었다. 감소하는 채널 길이를 갖는 MOSFET 문턱전압에 대한 roll-off 특성을 최소화하기 위해 generalized scaling에서 $\alpha$값은 1에 가깝게 되는 것을 볼 수 있었다.

• 유통과학연구
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• 제19권6호
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• pp.21-28
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• 2021

Purpose: Facing numerous challenges, organizational management is one of the most important research areas for organizations which handles workers' behaviors when they are within their workplace and organization to make more profits. The current research aims to analyze the effect of organizational management factors on direct employee consultation in distribution channels. Research design, data, and methodology: To achieve the purpose of the study and provide adequate empirical results, the current authors conducted the structural equation analysis using IBM AMOS 24.0 and collected 387 U.S employees in distribution channels (Wholesale and Retail shops). Results: Investigating the relationships between three organizational management factors and direct employee consultation, we found out that organizational practitioners in distribution channels face numerous challenges that must be resolved to ensure effective direct employee consultation to benefit employees. Empirical findings suggest that practitioners and leaders in distribution channels should focus on developing employee psychological management and utilizing direct employee consultation. Conclusions: In sum, the present research concludes that it must ensure that the employee in distribution channels should be a comfortable environment to appropriately respond to consultations. An approachable management team is ideal for employee consultations to find the right ways to keep employees at par with the consultation issues.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
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• pp.132-135
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• 2000

Direct current corrosion have being investigated by lots of scientists but Alternating current corrosion was ignored because the corrosion rate by AC was very small. Recently however, AC corrosion accidents have been reported in many other countries. So the study of AC corrosion is to be necessary in these days. In this paper, several experiments which intentionally imposed the AC or DC to the specimens also imposed AC and DC at the same time was carried out in the laboratory to examine the AC corrosion characteristics and in addition applied the same way in the field. Moreover, while the field investigations of the abnormal corrosion failures. It was the AC that caused one of corrosion failures.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권3호
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• pp.266-273
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• 2012

In conventional direct torque control (DTC) using space-vector modulation (SVM) of induction machine (IM) drives, at least three current sensors are needed. In this paper, a low-cost SVM-DTC strategy is proposed, in which only a single current sensor is used. The position of the voltage space vector is divided into two areas: effective and non-effective area. If it is located in the non-effective area, the voltage space vector will be shifted into the effective area with minimum distortion. Further, the switching frequency remains constant. The simulation is carried out on a MATLAB/Simulink platform and the simulated results verify the effectiveness of the proposed strategy.

• 한국자기공명학회논문지
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• 제23권2호
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• pp.46-50
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• 2019

Spin orbit torque would be applied as the next generation of MRAM, so many researchers are interested in related field. To make a more efficient device, electric current should convert into spin current with high efficiency. Moreover, it becomes important to measure efficiency of spin orbit torque accurately. We measured spin torque FMR of W/CoFeB hetero structure system with direct current. The efficiencies of the damping like torque and field like torque were measured by using the linewidth and on-resonance field proportional to direct current. In addition, we analyzed that a quadratic shift of the on-response field was caused by the Joule heating.

• 센서학회지
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• 제29권5호
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• pp.283-292
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• 2020

Current sensors that use a Hall element and Hall IC to measure the magnetic fields generated in steel silicon core gaps do not distinguish between direct and alternating currents. Thus, they are primarily used to measure direct current (DC) in industrial equipment. Although such sensors can measure the DC when installed in expensive equipment, ascertaining problems becomes difficult if the equipment is set up in an unexposed space. The control box is only opened during scheduled maintenance or when anomalies occur. Therefore, in this paper, a method is proposed for facilitating the safety management and maintenance of equipment when necessary, instead of waiting for anomalies or scheduled maintenance. A Bluetooth 4.0 low-energy current-sensor system based on near-field communication is used, which compensates for the nonlinearity of the current-sensor output signal using a piecewise linear model. The sensor is controlled using its generic attribute profile. Sensor nodes and cell phones used to check the signals obtained from the sensor at 50-A input currents showed an accuracy of ±1%, exhibiting linearity in all communications within the range of 0 to 50 A, with a stable output voltage for each communication segment.

• Journal of Power Electronics
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• 제12권3호
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• pp.410-417
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• 2012

In this paper, a direct current control method based on a one-cycle controller (DCOCC) for double frequency buck converters (DF buck) is proposed. This control method can make the average current through the high frequency and low frequency inductors of a DF buck converter equal. This is similar to the average current control method. However, the design of the loop compensator is much easier when compared with the average current control. Since the average current though the high frequency and low frequency inductors is equivalent, the current stress of the high frequency switches and the switch losses are minimized. Therefore, the efficiency of the DF buck converter is improved. Firstly, the operation principle of DCOCC is described, then the small signal models of a one cycle controller and a DF buck converter are presented based on the state space average method. Eventually, a system block diagram of the DCOCC controlled DF buck is established and the compensator is designed. Finally, simulation and experiment results are given to verify the correction of the theory analysis.

• 한국전기전자재료학회논문지
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• 제27권2호
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• pp.104-109
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• 2014

To operate organic light emitting device (OLED) with alternating current (AC) power source without AC/DC(direct current) converter, we fabricated the fluorescent OLED and measured the emission characteristics with AC and DC. The OLED operated by AC showed higher maximum current efficiency of 8.2 cd/A and maximum power efficiency of 8.3 lm/W. But current efficiency and power efficiency of AC driven OLED showed worse than DC driven OLED at high voltage above 10 V. This result can be explained by the peak voltage of AC was $\sqrt{2}$ times than DC, In case of low driving voltage the emission characteristics were improved by the peak voltage of AC, but in case of high driving voltage the emission efficiencies were decreased by the roll off phenomena. Finally, serial OLED arrays using twelve OLEDs driven by AC 110 V showed average voltage of 9.17 V, voltage uniformity of 99.0%, average luminance of $1,175cd/m^2$, luminance uniformity of 94.4%.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.522-524
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• 2018

A New Direct AC LED Driver has been proposed for wide output power range and precise constant current regulation using an advanced auto commutation topology. The conventional shunt regulation method provides a stepped input current shape by fixed regulation references in the linear regulator of the each channel, which results in poor current regulation and high THD. The conventional method needs to assign a linear regulator in each LED channel so that the number of linear regulator increases when extending the number of channels especially at high power application. The proposed regulation method can drive multiple switches to regulate each LED channel current by a single amplifier with sinusoidal reference so that large number of LED channel can be simply extended with less BOM cost and low THD is obtained with the accurate current regulation thanks to the sinusoidal input current control in the closed loop control. To confirm the validity of the proposed circuit, theoretical analysis and experimental results from a 20-W LED driver prototype are presented.