• 지질공학
• /
• 제24권1호
• /
• pp.69-79
• /
• 2014

본 연구의 목적은 토양침식에 관련되는 강우특성, 토양경사도, 그리고 지질특성의 상대적인 중요도를 규명하는데 있다. 이 목적을 달성하기 위하여, 강우강도, 토양경사도, 지질특성의 각각 다른 조건에서 실내 인공강우실험 및 현장조사를 실시하였다. 실내시험 결과에 의하면, 토양침식량은 토양 경사도가 강우강도보다 크게 영향을 받았다. 유출량은 강우량에 비례하며, 점토함량이 높을수록 증가한다. 따라서 토양의 유기물과 점토 함량이 큰 토양에서 토양침식량이 크게 증가 하였다. 현장시험 결과로는 토양경사가 큰 지역 및 퇴적암 지역보다 변성암 지역에서 보다 큰 침식량이 계산되었다. 이러한 실험의 결과는 토양침식량을 예측하는 모델개발에 있어서 기반암 풍화의 산물인 토양에서의 지질특성이 침식 및 침식후의 퇴적특성을 잘 반영하고 있음을 보여준다.

• Journal of Welding and Joining
• /
• 제5권2호
• /
• pp.27-34
• /
• 1987

The characteristics of arc sprayed layer were studied with hardness test and microstructural observation. The erosion resistance of arc sprayed layer was also evaluated using a method of steel ball blasting test which was proposed in this study as a test method for measuring the erosion properties in the impact wear condition. By an impact of the molten droplets on the redeposited substrate, lamella structure was formed which contains laminated oxide layers, fissures, and porosities. As a result of mechanical tests, it was shown that the sprayed specimen showed higher hardness than the substrate, but it resulted in higher erosion rate than the substrate. The poor erosion property obtained with a sprayed coating was considered to be attributable to easy flaking off the the layers laminated with brittle oxide layers.

• Tribology and Lubricants
• /
• 제9권1호
• /
• pp.55-61
• /
• 1993

Recently, due to the erosion damage that were generated increasingly at alloy metals of slide bearing by cavity of lubricating oil with tendency of high speed and high output of reciprocating engine, there is a need to study the process on the formation of cavitation erosion, and the characteristic of cavitation erosion at lubricating oil environments under various condition for marine ship. Therefore, the apparatus of cavitation erosion experiment used 20 KHz, $24 \mu m$ piezoelectric vibrator. The main results obtained through this test method are as follows: 1. The max. erosion rate at lubricating oil environments was related to the change of space, oil film thickness, and shown to tendency of gear oil>system oil>turbine oil>mixed oil environments with different viscosity. 2. The pitted hole by cavitation erosion at high viscosity oil environments became small and deep, and in addition to, they appeared to be wide and shallow at low viscosity.

• 한국표면공학회지
• /
• 제23권2호
• /
• pp.11-17
• /
• 1990

The erosion characteristice of plasma-sprayed tungsten carbide chromium carbide coatings were investigated. Erosion tests were perfomed at room temperature by using Al2O3 and SiC particles accleerated in air stream. Weight losses of the coatings were measured over a range of paricle velocities and impingement angle. It was found that, for both of this coatings, the maximum erosion occurrd at a normal angle of impact, and the erosion rate at this impact angle was a power function of pparticle velocity. The values of the velocty emponent were between 3.07 and 3.50 Erosion value of chromium carbide coating was higher than that of tungsten carbide coating.

• Corrosion Science and Technology
• /
• 제20권3호
• /
• pp.143-151
• /
• 2021

In this study, optimal shot peening process conditions were investigated for improving the cavitation erosion resistance of gray cast iron under a marine environment. Shot peening was performed with variables of injection pressure and injection time. The durability was then evaluated through cavitation erosion test which was conducted according to the modified ASTM G-32 standard. The tendency of cavitation erosion damage according to shot peening process condition was investigated through weight loss rate, surface and cross-sectional analysis of the specimen before and after the test. As a result, the shot peening process condition that could minimize cavitation erosion was when the injection pressure was the lowest and when the injection time was the shortest. This was because the flake graphite exposed on the gray cast iron surface could be easily removed under such condition. Therefore, the notch effect can be prevented by surface modification. In addition, the cavitation erosion damage mechanism of gray cast iron was discussed in detail.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2006년도 춘계 학술발표회 논문집
• /
• pp.455-465
• /
• 2006

In this study, the effect of scour was evaluated by regional and geotechnical characteristics and back data were accumulate for the design against scour through the local erosion characteristics evaluation of the Inchon coast. The erosion characteristics for the undisturbed soil samples collected near the main locations at the Incheon 2nd bridge, the Hwangyeong bridge, and a coast road in Songdo, are determined quantitatively through the scour rate tests. On the basic soil properties test, the bed around the Inchon coast chiefly consists of fined grained soils, and the soil samples were classified as silty clay(ML) or clay(CL) under the Unified Soil Classification System. On the scour rate test, the critical shear stress increases when the undrained shear strength increases as of the general trend of fine grained soils, and the average scour rate for the maximum velocity by 100 year flood is 173mm/hr at the Incheon 2nd bridge, 67mm/hr at the Hwangyeong bridge and 10mm/hr at a coast road in Songdo, respectively. Comparing to the scour rate of coarse grained soil, that of the bed around the Inchon coast is turned out to be very low. Therefore, the relative ability of the bed around the Inchon coast to resist erosion is assumed to be very high.

• Journal of Electrical Engineering and Technology
• /
• 제12권6호
• /
• pp.2348-2352
• /
• 2017

The electrical contact characteristics including temperature rise, contact resistance and arc erosion rate of the $Ag-SnO_2$ materials with increased $SnO_2$ content were investigated during the repeated make-and-break operations. The thickness of arcing melting layer reduces by half and the arc erosion rate decreases more than 70% under 10000 times operations at AC 10 A with the $SnO_2$ content increasing from 15 wt.% to 45 wt.%, on one hand, temperature rise and contact resistance increase obviously but could be reduced to the same order of conventional $Ag-SnO_2$ materials by increasing the contact force. The microstructure evolution and the effect of $SnO_2$ on the arc erosion, contact resistance were analyzed.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
• /
• pp.185-186
• /
• 2000

For the quantitative investigation of the erosion of MgO layers in real ac-PDP cells, we constructed a microscopic spectrophotometer which is capable of measuring transmission spectra from the area as small as 20 ${\times}$ 20 ${\mu}m^2$. In the test on the sputtered MgO films with a thickness gradient, we were able to probe the thickness variation of 1000 nm over $1000-{\mu}m$ distance. Using this instrument, we were able to determine not only the erosion rate at the particular position of ac-PDP cells but also the relative erosion rate at different positions in a single ac-PDP cell.

• Journal of Welding and Joining
• /
• 제15권1호
• /
• pp.125-134
• /
• 1997

This study was conducted by L9 orthogonal array to obtain optimum spray parameters for This study was conducted by L9 orthogonal array to obtain optimum spray parameters for $Cr_3C_2 - 7wt%$(80wt%Ni-20wt%Cr) coating powder. The factors were hydrogen flow rate, oxygen flow rate, gun-to-work distance, powder feed rate. And evaluation methods for the coating were surface roughness, oxygen concentration, micro-hardness, pore size and distribution, low angle ($30^{\circ}$) erosion rate, and microstructure of coating. The optimum HVOF spray conditions were proved as follows : hydroen flow rate ; 681 SLPM, oxygen flow rate ; 215 SLPM $H^2/O^2 ratio= 3.16), gun-to-work distance ; 22cm, powder feed rate; 25g/min. The hardness (Hv300) was 1147 and the erosion rate ($30^{\circ}$degree) was $3.16\times10^{-4}$g/g. It is believed that the optimized spray conditions can be improved the wear-resistance and anti-erosion characteristics of the coating.

• 전기학회논문지
• /
• 제68권1호
• /
• pp.61-68
• /
• 2019

Only the power is converted from AC to DC, in accordance with IEC 60587 based test method, in order to develop the LSR(Liquid Silicone Rubber) insulator material for HVDC, the experiment of Inclined Plate Tracking and Erosion Resistance was conducted. A contaminant (2.5 mS/cm: ammonium chloride) was applied at a rate of 0.3 ml/min and a voltage of ${\pm}3.5kV$, and was evaluated on the basis of 60 mA/2s. The samples were prepared by dispersing LSR/Nano silica_25wt% Composites in LSR. The erosion phenomena of surface discharge and tracking due to DC polarity and negative polarity were measured by image, leakage current maximum and thermal camera. The thermal imaging camera measured the surface temperature generated by the joule heat of the leakage current due to the drying discharge and the conductive current. After the measurement, the tracking and erosion mechanisms were evaluated for erosion weight, erosion depth and erosion length. Positive and negative polarity of LSR/Nano Silica_25wt% composite Tracking and erosion results show that positive polarity is more severe than negative polarity.