• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1497-1498
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• 2011

본 논문에서는 -50[$^{\circ}C$]환경에서 케이블 접속함의 극한지역 적용가능 여부를 확인하기 위해 접속함의 주재료인 Etylene Propylene Rubbe(EPR), Silicone Rubber(SR) 및 Epoxy의 물성 및 특성 평가 시험을 진행하였다. 실험방법은 DSC(Differential Scanning Calorimetry)를 사용하여 10[$^{\circ}C$]/min의 승온속도로 각각의 온도구간에서 샘플들의 Tg(Glass Transition Temperature)를 측정하였고, UTM(Universal Testing Machine)으로 -50[$^{\circ}C$]~ 상온에서 인장강도 및 신율을 측정하였다. 본 연구를 동하여, 극한지역의 전력계통 연계 안정성 및 신뢰성 향상을 위한 기초적인 Data-base를 구축했다.

• Smart Structures and Systems
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• 제30권2호
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• pp.183-193
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• 2022

Structural health monitoring and structural vibration control are multidisciplinary and frontier research directions of civil engineering. As intelligent materials that integrate sensing and actuation capabilities, shape memory alloys (SMAs) exhibit multiple excellent characteristics, such as shape memory effect, superelasticity, corrosion resistance, fatigue resistance, and high energy density. Moreover, SMAs possess excellent resistance sensing properties and large deformation ability. Superfine NiTi SMA wires have potential applications in structural health monitoring and micro-drive system. In this study, the mechanical properties and electrical resistance sensing characteristics of superfine NiTi SMA wires were experimentally investigated. The mechanical parameters such as residual strain, hysteretic energy, secant stiffness, and equivalent damping ratio were analyzed at different training strain amplitudes and numbers of loading-unloading cycles. The results demonstrate that the detwinning process shortened with increasing training amplitude, while austenitic mechanical properties were not affected. In addition, superfine SMA wires showed good strain-resistance linear correlation, and the loading rate had little effect on their mechanical properties and electrical resistance sensing characteristics. This study aims to provide an experimental basis for the application of superfine SMA wires in engineering.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.930-933
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• 2001

Titanium Alloys used in this experiment has an good corrosion resistance and specific strength, and is the new material developed for medical supplies living goods. In this study the rolled titanium alloy is done by annealing, solution heat-treatment and aging and then is worked by wire EDM. With changing the process conditions, the process properties of surface hardness, surface roughness, shape of process surface and the analysis of ingredients are measured through experiment repeating main cut and finish cut. It is confirmed to gain good measure values as increasing the number of processing of wire EDM. In this experiment the phenomena of processing is studied and the appropriate process condition is proposed.

• 동력기계공학회지
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• 제9권4호
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• pp.90-95
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• 2005

The wire-arc process is a low-cost thermal spray method simply utilizes electrical energy to melt the feedstock wire. It is more userful for field applications, especially to coat large surface area. In this paper, a special Fe-based alloy coatings by using the wire-arc process were developed. Nanoscale composite coatings were achieved either during spraying or through a post heat treatment. As-sprayed Fe-based alloy coatings had been an amorphous matrix structure, after heating to $700^{\circ}C$ for 10 minutes a solid state transformation occurred in the some fraction of amorphous matrix which resulted in the formation of nanostructured recrystallized phase. Scanning electron microscopy (SEM) and field emotional scanning electron microscope(FE-SEM) were applied to analyze the microstructure of the coatings. Additionally hardness and bend resistance of the Fe-based alloy coatings were examined, and these results were compared with those of partially stabilized zirconia(PSZ) coatings by using the plasma spray process.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.497-499
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• 2003

This paper analyses the lightning overvoltage with earth of grounding wire and installation types of arresters in double circuits distribution systems. First, the model for analysis is selected severer case between upper line and lower line when the direct lightning surge strikes on the overhead grounding wire. The lightning overvoltage is variously calculated with earth distance between overhead grounding wires. This paper also analyses the effect of the installation distance between arrestors and the earth resistance of overhead grounding wire. From these results, authors examine the rationality of BIL that is applied in distribution system.

• 전기학회논문지P
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• 제66권4호
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• pp.219-223
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• 2017

In this paper, we calculated the losses in the high voltage lines of power distribution system. The losses caused by high voltage lines are calculated using maximum current, resistance, loss factor, and dispersion loss factor. The accurate extraction of these factors are very important to calculate the losses exactly. Thus, the maximum loads are subdivided to regions and calculated monthly for more accurate maximum current calculation. Also, the composite resistance is calculated according to the ratio of the used wire types. In order to calculate the loss factor, the load factors according to the characteristics of each region were calculated. Finally, the losses of the distribution system is calculated by adding the losses by the transformers and the low voltage lines.

• 한국전기전자재료학회논문지
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• 제30권5호
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• pp.301-306
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• 2017

Wire electrical discharge machining (WEDM) process was evaluated to slice Silicon (Si) for various applications. Specifically, various Si workpieces with various resistances, such as single and multi crystalline Si bricks and wafers were used. As conventional slicing processes, such as slurry-on or diamond-on wire slicing, are based on mechanical abrasions between Si and abrasive, there is a limitation to decrease the wafer thickness as well as kerf-loss. Especially, when the wafer thickness is less than $150{\mu}m$, wafer breakage increases dramatically during the slicing process. Single crystalline P-type Si bricks and wafers were successively sliced with considerable slicing speed regardless of its growth direction. Also, typical defects, such as microcracks, craters, microholes, and debris, were introduced when Si was sliced by electrical discharge. Also, it was found that defect type is also dependent on resistance of Si. Consequently, this study confirmed the feasibility of slicing single crystalline Si by WEDM.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.2173-2174
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• 2011

At the moment, the section insulators for different phases used for over head contact wire system has been all imported since its first application. However, because the section insulators need frequent maintenance and replacement due to the wear by the friction with pantograph and the contamination, which causes its life shorter than as expected, it is required to develop the insulation material with better wear-resistance characteristics and contamination-resistance characteristics. In this thesis, the author developed the section insulator which adopts Teflon tube insulation material which is composed of the Teflon material with the excellent electrical characteristics and wear-resistance characteristics for a longer expected life than that made of conventional FRP.

• 전기학회논문지P
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• 제59권4호
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• pp.434-439
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• 2010

This study fabricated a simulation facility which reduced the structure of a current distribution line to 50:1 in order to analyze the induced lightning shielding effect of a 22.9kV-Y distribution line according to ground resistance capacity, grounding locations, etc. When installing an overhead ground wire, the standard for grounding a distribution line with a current of 22.9kV-Y requires that ground resistance in common use with the neutral line be maintained less than $50\Omega$every 200m span. The reduced line for simulation had 7 electric poles and induced lightning was applied to the ground plane 2m apart from the line in a direction perpendicular to it using an impulse generator. If induced voltage occurred in the line and induced current flowed through the line due to the applied current, the induced voltage and current of the 'A' phase were measured respectively using an oscilloscope. When all 7 electric poles were grounded with a ground resistance of less than $50\Omega$ respectively, the combined resistance of the line was $7.4\Omega$. When an average current of 230A was applied, the average induced voltage and current measured were 1,052V and 13.8A, respectively. Under the same conditions, when the number of grounding locations was reduced, the combined resistance as well as induced voltage and current showed a tendency to increase. When all 7 electric poles were grounded with a ground resistance of less than $100\Omega$, the combined resistance of the line was $14.9\Omega$. When an average current of 236A was applied, the average induced voltage and current of the 'A' phase calculated were 1,068V and 15.6A, respectively. That is, in this case, only the combined resistance was greater than when all 7 electrical poles were grounded, and the induced voltage and current were reduced. Therefore, it is thought that even though ground resistance is slightly higher under a construction environment with the same conditions, it is advantageous to ground all electric poles to ensure system safety.

• 전기전자학회논문지
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• 제8권1호
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• pp.63-72
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• 2004

The supply voltage has been drop rapidly and the total length of the wire increased exponentially in the nanometer SoC design environment. The ideal supply voltage was dropped sharply by the resistance and parasitic devices which stayed on the kilometers-long wire length. Even worse, it could severely affect the functional behavior of the block of the design. To analyze the effects of the long wire of the SoC while maintaining the accuracy, the modeling of the current and the RC conversion of the parasitic techniques are researched and applied. By these modeling and conversion, the multi-million gates HDTV Chipset can be analyzed within a day. The benchmark analysis of the HDTV SoC showed the superiority to the conventional methods in performance and accuracy.