• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 E
• /
• pp.1788-1790
• /
• 1998

The dielectric layers in AC plasma display panel(AC PDP) are essential to the discharge cell structure, because they protect metal electrodes from sputtering by positive ion bombarding in discharge plasma and form a sheath of wall charges which are essential to memory function of AC PDP. This layer should have high dielectric strength and also be transparent because the luminance of PDP is strongly correlated this layer. In this paper, we discussed the dielectric strength and transparency of the dielectric layer under various conditions. As a result, on the $15{\mu}m$ thickness, the minimum dielectric strength was $29V/{\mu}m$ and the transmittance coefficient was about 80% after $570^{\circ}C$ firing process. It can be proposed that the resonable dielectric thickness in AC PDP is $15{\mu}m$ because it has about 80V margin on the maximum applied voltage.

• 전기학회논문지
• /
• 제63권6호
• /
• pp.780-785
• /
• 2014

To assess the deterioration condition of stator insulation, diagnostic and AC dielectric strength tests were performed on five high voltage (HV) motors (2,000 HP, 6.6 kV) for boiler feed-water pump (BFP). Two HV motors for BFP were installed per unit. Following the long term rewinding program, the diagnostic test was performed on five 6.6 kV motors during the planning maintenance period. After completing diagnostic test, AC dielectric strength test was done on the stator windings of HV motors. The AC dielectric strength test was conducted at 15 kV for one minute. Dielectric strength test and diagnostics test results confirmed that the stator insulation was judged to be in serviceable condition in the five 6.6 kV motors.

• 한국전자파학회논문지
• /
• 제22권10호
• /
• pp.1016-1019
• /
• 2011

본 논문에서는 코드 영역에서의 pilot 채널의 전기장 강도를 측정하여 WCDMA 기지국에서 방사되는 전기장 강도의 최대값을 예측하였다. 사용된 방법의 타당성을 제시하기 위하여 자체 제작한 시험 기지국에서 광선 추적법을 이용한 이론값과 전체 대역에 대한 전기장 강도 측정 결과와 비교하여 90 % 이상 일치함을 확인하였다. 그리고 실제 운용 중인 기지국을 대상으로 채널 전체에 대한 전기장 강도 측정 결과를 논문에서 제안한 방법으로 예측한 결과와 비교하였다. 비교한 결과, pilot 채널을 이용하면 최대 트래픽 상태의 전기장 강도를 예측할 수 있음을 확인하였다. 본 측정방법은 국내 무선국 전기장 강도 검사에 효과적으로 적용될 수 있다.

• 한국세라믹학회지
• /
• 제34권8호
• /
• pp.877-885
• /
• 1997

The dependence of strength, crack growth, fracture mode and degree of domain rearrangement of PZT ceramics on poling strength were studied. The PZT [(Pb0.94Sr0.06)(Zr0.46Ti0.54)O3+Nb(trace)] specimens were poled at 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 kv/mm, and the strength of the specimens was measured by 3 point flexure system. The bending strength of the specimen decreased in different modes according to the bending directions; xz, zx and yz plane direction with x axis of the poling direction in Cartesian coordinate system. The strength differences between the directions increased as the poling strength increased. The fracture mode transferred to intergranular fracture mode from transgranular one as the poling strength increased. The mechanical breakdown occurred when the poling strength higher than 3 kV/mm was applied to the specimen. It was observed that the crack length increased in the normal direction to the poling direction, however, decreased in the parallel direction to the poling direction when the poled PZT specimen was indented by the Vickers indenter. However, the crack produced by indentation continuously was continuously increased little by little after indentation on the specimen. The domain rearrangement occurred as the poling strength increased and the domains were rearranged more effectively when the electric field was continuously increased little by little.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
• /
• pp.45-46
• /
• 2016

As the demand for super tall buildings is currently increased in domestic and foreign countries, some kinds of ultra-high strength concretes are being developed actively. Since the cross section of concrete becomes smaller thanks to such kinds of ultra-high strength concretes, the concrete structures can be much bigger, more gigantic and much ultra-high. And as another benefit which is generated thanks to the enhancement of the durability performance, the maintenance expenses are also saved. However, since low W/B ultra-high concrete has a high possibility that many cracks can occur in the initial period due to the self-shrinkage caused by the self-desiccation as one of the blending characteristics, the problem becomes bigger by influencing the safety of a structure. Therefore, in this study, it is intended to analyze the effects of substituting some limestone-based ultra-high strength mortar with electric arc furnace oxidizing slag fine aggregates on the self-shrinkage of mortar.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
• /
• pp.263-263
• /
• 2008

This paper describes the electrical strength of a toughened glass stem insulators employed for electric railways. The broken glass stem insulators for comparison were taken at site. According to the international standards, electrical strength tests with 60[Hz] voltage and with impulse voltage were carried out to them under dry and wet condition and the results were corrected by considering the temperature and humidity factors. Based on the experimental results, the electrical strength of broken glass stem insulators was compared with those of sound ones and surface flashover characteristics were also discussed. As a result, it was confirmed that the electrical discharge is formed by bridging each end of the insulator shell. The experimental results are expected to be utilized as data for electrically identifying the failure causes of glass insulators.

• 소성∙가공
• /
• 제31권2호
• /
• pp.57-63
• /
• 2022

The current study performed formability analysis of a heat exchanger separator for an electric vehicle to apply a high-strength aluminum sheet based on parametric analysis. Mechanical properties for sheet metal forming simulation were evaluated by tensile test, bulge test, and Nakajima test. Two-stage crash forming was established by considering the mass production process using conventional low-strength aluminum sheets. In this study, FEM for the two-stage forming process was conducted to optimize the corner radius and height for improving the formability. In addition, the possibility of a one-stage forming process application was confirmed through FEM. The prototype of the sample was manufactured as FEM results to validate the parametric analysis. Finally, this result can provide a one-stage forming process design method using the high-strength aluminum sheet for weight reduction of a heat exchanger separator for an electric vehicle.

• Structural Engineering and Mechanics
• /
• 제82권6호
• /
• pp.713-724
• /
• 2022

Effects of coal tensile strength and plow configuration on the coal fragmentation process was modeled by two-dimensional particles flow code (PFC2D). Three tensile strength values, 0.5, 1,5 and 3.5 MPa were considered in this numerical study. The cutters of plow penetrated in the coal for 4 mm at a rate of 0.016 m/s. According to the PFC manual, the local damping factor was 0.7. Three failure mechanism of coal during the fragmentation process by plow were modelled. The coal material beneath the cutters showed the elastic, plastic and fracturing behaviors in this analysis. In all the models, the plastic zone was fractured and some micro-cracks were induced but the elastic zone remained undamaged. It was observed that the tensile strength affected the failure mechanism of coal significantly and as it increased the extent of the fractured zone underneath the plow cutter decreased during the fragmentation process.

• 한국구조물진단유지관리공학회 논문집
• /
• 제21권4호
• /
• pp.97-103
• /
• 2017

본 논문은 전기로 산화슬래그 골재를 사용하여 콘크리트를 제작하여 물리적 성능을 평가하였다. 실험은 전기로 산화슬래그 골재를 치환하여(잔골재-굵은골재) 0%-0%, 0%-100%, 50%-100%, 100%-100%으로 각 4수준으로 일반강도영역 W/C 45%와 고강도영역인 W/C 30%의 2수준으로 제작하여 진행하였다. 굳지 않은 콘크리트에서는 공기량, 플로우 및 슬럼프, 단위용적질량 실험을 진행하였으며, 경화 콘크리트에서는 압축강도 및 휨강도, 단위용적질량 실험을 통하여 물리적 특성을 검토하였다. 본 연구의 실험결과 전기로 산화슬래그의 혼입량이 증가함에 따라 콘크리트의 강도 증진 효과가 나타났으며, 이는 전기로 산화슬래그 골재 내에 ${\beta}-C2S$로 인하여 골재 내외부에서 강도 증진 효과를 발휘한 것으로 사료된다.

• 한국기계가공학회지
• /
• 제20권12호
• /
• pp.44-53
• /
• 2021

As environmental issues have emerged worldwide, emission gas regulations have been strengthened. In the construction machinery sector, studies have been actively conducted to utilize the power source of electric motors owing to the increasing demand for zero emissions. In this study, the gear specifications of an electric axle for construction machinery were selected by considering the specifications of the motor, gear tooth contact pattern, and face load factor. The gear strength evaluation was performed at the system level using the simulation model. The bending and contact strength of the spiral bevel gears and the bending strength of the planetary gear set showed a safety factor of 1 or more. However, the contact strength of the planetary gear set showed a safety factor of 0.92. Conservative results were derived by performing the analysis under the rated load condition of the motor. However, the ratio of the equivalent torque to the rated torque of the motor was 45% or less, hence, it was determined that no difficulties should arise regarding the durability of the axle.