• E2M - 전기 전자와 첨단 소재
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• 제8권4호
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• pp.495-503
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• 1995

As lengthen gap leng of artificial needle shape void 0.24.rarw.1.5[mm]), the amplitude of AE(Acoustic Emission) pulses was enlarged and number of pulses be generated was few. The longer gap length of void, the shorter breakdown time. As a result of this, I found that existen of void in insulation mate was fatal deterioration of insulation. According to phase angle of applied voltage, time being void was scattered largely in region of phase angle of pulses of origination in phase angle of applied voltage. The result will be used to analysis of void diagnosis.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.480-484
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• 2006

We propose a new PDP cell structure named DIDE (Dual Ignition Discharge Electrodes) structure with a long electrode gap to realize a high luminous efficacy. Suggested DIDE structure basically has a long electrode gap $(200{\mu}m{\sim}400{\mu}m)$, nevertheless, because of auxiliary electrodes formed on the front panel, can be driven at relatively low voltage. The discharge characteristic of DIDE structure was much different from that of conventional structure, which was analyzed by IR emission images using IICCD (Image Intensified Charge Coupled Device). The study can explain some particular characteristics of DIDE structure. As a result, the long electrode gap and low voltage effect can be expected in DIDE structure, and a very high luminous efficacy of 7.5 lm/W has been achieved in monochrome green test panel adopting the new cell structure with Ne-Xe (12%) mixture at 400 torr.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.95-98
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• 2003

The positive column discharge characteristics in the long gap (440 ${\mu}m$) are investigated based on the voltage distribution among three electrodes. In particular, the effects of the amplitude and width of the short pulse applied to the address electrode on the positive column discharge characteristics are examined intensively. By proper controlling of the amplitude and width of the address short pulse, it is found that the positive column discharge in the long gap is well constructed. As a result, under the stable static voltage margin condition, the firing and sustaining voltages are as low as those of conventional short gap(60 ${\mu}m$) discharge($V _f=220V$, $V_s=150V$) and the color purity is improved. Moreover, the luminous efficiency increases up to 60% in comparison with the conventional case.

• 한국자동차공학회논문집
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• 제4권1호
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• pp.123-133
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• 1996

From the experimental study of wire-cut Electric Discharge Machining of alloyed tool steel and tungsten carbide, the characteristics such as cutting speed, surface roughness has been observed and evaluated for various conditions. Cutting speed is improved as peak discharge current and wire tension become increased, and gap voltage and spark cycle decreased. Surface roughness can be better when peak discharge current and gap voltage become smaller, or spark cycle and wire tension become larger. Secondary cut is recommended to obtain high precision and good quality.

• Journal of Welding and Joining
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• 제13권4호
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• pp.75-84
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• 1995

In GMA welding of sheet metal, the short circuit metal transfer mdoe is preferred because of its low heat input and capability of bridging the root gap. The molten electrode is transferred to the workpiece during repectitive short circuit in the model. The waveform of welding current or voltage and the frequency of short circuiting are affected by a number of factors including: magnitude of welding current and voltage, root gap, electrode extension, power supply characteristics, and so on. In this study experimental models were proposed, which are able to determine the relationship between the root gap and short circuit frequency and the relationship between the root gap and appropriate welding speed that produces the good quality of back bead without burn through. Using the experimental models, the root gap can be obtained from measuring the short circuit frequency, and then the appropriate weldig speed to the root gap can be determined. Thus a back bead control system was constructed by controlling the welding speed for maintaining the quality of back bead. The developed system has shown the successful capability of back bead control.

• 전기학회논문지
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• 제63권1호
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• pp.80-84
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• 2014

The discharge characteristics of Surface Dielectric Barrier Discharge (SDBD) reactor are investigated to find optimal driving condition with adjusting various parameter. When the high voltage with sine wave form is applied to SDBD source, successive pulsed current waveforms are observed owing to multiple ignitions through the long discharge channel and wall charge accumulation on the dielectric surface. The discharge voltage, total charge between dielectrics, mean energy and power are calculated from measured current and voltage according to electrode gap and dielectric thickness. Discharge mode transition from filamentary to diffusive glow is observed for narrow gap and high applied voltage case. However, when the diffusive discharge is occurred with high applied voltage, the actual firing voltage is always lower than that with low driving voltage. The $Si_3N_4$, $MgF_2$, $Al_2O_3$ and $TiO_2$ are considered for dielectric protection and high secondary electron emission coefficient. SDBD with $MgF_2$ shows the lowest breakdown voltage. $MgF_2$ thin film is proposed as a protection layer for low voltage atmospheric dielectric barrier discharge devices.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.605-608
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• 2001

With the intention of investigating the breakdown properties of oil-immersed transformer oils in temperature range of $20\sim100[^{\circ}C]$, we are made researches AC breakdown in the gap of $500\sim2500[{\mu}m]$. The classification for the physical properties of oil for oil-immersed transformer by FTIR and H-NMR experiments was confirmed to type of mineral oils. As the dependance of breakdown properties due to electrode gap length variation, breakdown voltage was found increasing according to the increase of gap, while dielectric strength was decreasing. As a result the characteristics for AC breakdown, It goes to prove that the breakdown voltage was increased to $90[^{\circ}C]$ but decreased over $90[^{\circ}C]$ in the temperature range. Also, breakdown voltage was found increasing in the increase of gap and the rising of temperature according to Weibull distribution.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.254-257
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• 1997

In this paper, we investigated the effects of gap length and tip radius influenced in breakdown of mineral based insulation oil Electrode system was needle-plane geometry It is to model conductive extrusions in oil filled electrical power apparatus. The tip radius of needle electrode was 5, 10, 20 and 25${\mu}{\textrm}{m}$, respectively. We measured breakdown voltage for each of tip radius with increasing electrode gap, 2mm to 12mm. It was calculated electrical breakdown strength at tip using Mason\`s equation from breakdown voltage As gap lenght increased. breakdown strength increased linearly. But, as tip radius of needle increased, breakdown strength decreased exponentially. It can be explained by tole phenomenon that electron is easily injected, as tip radius increases, and effective work function decreases. When appling DC voltage. breakdown 7tr7ilgtll was higher wheal polarity of needle was negative than positive. It is because of the space charge effect ill accordance with the influence of liquid motion.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1480-1482
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• 2000

This paper investigated that resonant frequencies of Air-Gap microstrip patch antenna were tunable when piezoelectric material were used as the antenna substrates. The resonant frequencies of the air-gap antenna using the piezoelectric substrate were able to be controlled by applied AC voltage. The frequency variation of the antenna was great when PZT were applied voltage of the resonant frequency.

• 전력전자학회논문지
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• 제27권1호
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• pp.80-83
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• 2022

This paper proposes an initial rotor polarity detection algorithm of a single-phase permanent magnet synchronous motor (SP-PMSM) related to stable open-loop starting for sensorless operation. Generally, the SP-PMSM needs an asymmetric air-gap structure to can avoid the initial starting failure at zero torque point. Therefore, the rotor polarity information can be obtained by using the DC offset current direction of a stator current through a high frequency voltage injection into an SP-PMSM with an asymmetric air gap. In this paper, the proposed rotor initial polarity detection algorithm is verified through several experimental results.