• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.585-592
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• 2002

Discharge capacity of PBD is the most important factor of specification items to control any product of PBD. There is no standard specification for the PBD. Because the degree of discharge capacity is related to well resistance, install depth, maximum strain etc in the field. Discharge capacity test of PBD, permeability test of filter are conducted using PBD materials used in Korea. This paper proposes the critical discharge capacity for deep PBD under condition of non well resistance based upon their test and theoretical calculation. It was found that discharge capacity more than about 10 ㎤/sec is enough to undergo designing of deep PBD without well resistance.

• Mycobiology
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• 제31권3호
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• pp.173-178
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• 2003

India has maximum genetic materials in early cauliflower, which grow in subtropical conditions. Different disease parameters like linear growth, maximum growth rate per day, AUDPC, apparent infection rate and percent diseased area were calculated in artificially inoculated plants. Apparent infection rate is not co-related with the black rot disease incidence and should never be considered during characterization of disease resistance and varietal screening. Based on the above disease parameters Kunwari-18, Phool Gobhi Kunwari, Kataki-7 and BT-10-2 were selected as moderately resistance to black rot in early cauliflower. These lines can be used for black rot prone area and also for black rot disease improvement programme. Considering the qualitative and quantitative parameters, slow rotting resistance cauliflower lines are selected as such for cultivation and would be best suited in integrated disease programme.

• Geomechanics and Engineering
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• 제33권2호
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• pp.133-140
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• 2023

Soil erosion can cause scouring and failures of underwater structures, therefore, various soil improvement techniques are used to increase the soil erosion resistance. The microbially induced calcium carbonate precipitation (MICP) method is proposed to increase the erosion resistance, however, there are only limited experimental and numerical studies on the use of MICP treatment for improvement of surface erosion resistance. Therefore, this study investigates the improvement in surface erosion resistance of sands by MICP through laboratory experiments and numerical modeling. The surface erosion behaviors of coarse sands with various calcium carbonate contents were first investigated via the erosion function apparatus (EFA). The test results showed that MICP treatment increased the overall erosion resistance, and the contribution of the precipitated calcium carbonate to the erosion resistance and critical shear stress was quantified in relation to the calcium carbonate contents. Further, these surface erosion processes occurring in the EFA test were simulated through the coupled computational fluid dynamics (CFD) and discrete element method (DEM) with the cohesion bonding model to reflect the mineral precipitation effect. The simulation results were compared with the experimental results, and the developed CFD-DEM model with the cohesion bonding model well predicted the critical shear stress of MICP-treated sand. This work demonstrates that the MICP treatment is effective in improving soil erosion resistance, and the coupled CFD-DEM with a bonding model is a useful and promising tool to analyze the soil erosion behavior for MICP-treated sand at a particle scale.

• 마이크로전자및패키징학회지
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• 제12권4호통권37호
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• pp.331-338
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• 2005

The rapid advances in high power light sources and arrays as encountered in incandescent lamps have induced dramatic increases in die heat flux and power consumption at all levels of high power LED packaging. The lifetime of such devices and device arrays is determined by their temperature and thermal transients controlled by the powering and cooling, because they are usually operated under rough environmental conditions. The reliability of packaged electronics strongly depends on the die attach quality, because any void or a small delamination may cause instant temperature increase in the die, leading sooner or later to failure in the operation. Die attach materials have a key role in the thermal management of high power LED packages by providing the low thermal resistance between the heat generating LED chips and the heat dissipating heat slug. In this paper, thermal transient characteristics of die attach in high power LED package have been studied based on the thermal transient analysis using the evaluation of the structure function of the heat flow path. With high power LED packages fabricated by die attach materials such as Ag paste, solder paste and Au/Sn eutectic bonding, we have demonstrated characteristics such as cross-section analysis, shear test and visual inspection after shear test of die attach and how to detect die attach failures and to measure thermal resistance values of die attach in high power LED package. From the structure function oi the thermal transient characteristics, we could know the result that die attach quality of Au/Sn eutectic bonding presented the thermal resistance of about 3.5K/W. It was much better than those of Ag paste and solder paste presented the thermal resistance of about 11.5${\~}$14.2K/W and 4.4${\~}$4.6K/W, respectively.

• The Plant Pathology Journal
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• 제37권2호
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• pp.200-203
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• 2021

Rice blast caused by the filamentous fungus Magnaporthe oryzae, is arguably the most devastating rice disease worldwide. Development of a high-throughput and reliable field blast resistance evaluation system is essential for resistant germplasm screening, resistance genes identification and resistant varieties breeding. However, the occurrence of rice blast in paddy field is easily affected by various factors, particularly lack of sufficient inoculum, which always leads to the non-uniform occurrence and reduced disease severity. Here, we described a procedure for adequately inducing the occurrence of rice seedling blast in paddy field, which involves pretreatment of diseased straw, initiation of seedling blast for the first batch of spreader population, inducing the occurrence of the second batch of spreader population and test materials. This procedure enables uniform and consistent infection, which facilitates efficient and accurate assessment of seedling blast resistance for diverse rice materials.

• 열처리공학회지
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• 제12권1호
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• pp.40-46
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• 1999

Rotary bending fatigue tests were carried out to investigate the improvement of fatigue limit in annealed and austempered spheroidal graphite cast iron. Main results obtained are as follows. (1) The tensile strength(hardness) of Series C is higher than that of Series B, and fatigue limits are 245MPa in Series C, 230MPa in Series B and 195MPa in Series A, respectively. (2) The fatigue limits of Series B and Series A are mainly governed by the resistance to fatigue crack initiation. Whereas, the fatigue limit of Series C is governed by the resistance to fatigue crack initiation and growth. The defect size and the resistance to crack initiation and growth should be considered to clarify the fatigue properties in spheroidal graphite cast iron. (3) Improvement of fatigue limit by half-austempering is more reasonable than that of full-austempering treatment in multi defective materials as spheroidal graphite cast iron.

• 한국정보통신학회논문지
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• 제14권7호
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• pp.1687-1692
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• 2010

본 논문에서는 Blu-ray 디스크의 기록을 위한 Laser Diode의 온도특성을 고려한 기록품질의 개선방법에 대해 연구했다. 주변 온도변화에 따라 Blu-ray Laser Diode는 전류-전압 관계로부터 미분저항이 변화하게 되는데 이러한 미분저항이 저온에서 기록품질에 미치는 영향에 대해 분석하고 개선하는 방법을 제안한다.

• 한국표면공학회지
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• 제16권3호
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• pp.98-107
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• 1983

A study on the improvement of wear resistance of brasses by electroplating and diffusion treatment of tin was carried out. The optimum condition of the treatment obtained was as follows. Plating thickness of tin : 5 - 9 $\mu\textrm{m}$ Condition of diffusion treatment : atmosphere ; fused nitrate bath (KNO3 + NaNO3) temperature and time ; 1st step 320$^{\circ}C$, 60min. and 450$^{\circ}C$, 30min. During the diffusion treatment, internetallic compounds of Cu-Sn were formed and these compounds were identified as η, $\varepsilon$ and $\delta$ phase from the outer tin layer. It was considered that the improvement of wear resistance of brasses by the treatment is because of the formation of intemetallic compounds particalarly $\varepsilon$phase which is very hard, between soft tin layer brass.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 추계학술대회
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• pp.503-505
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• 2009

본 논문에서는 Blu-ray 디스크의 기록을 위한 Laser Diode의 온도특성을 고려한 기록품질의 개선방법에 대해 연구했다. 주변 온도변화에 따라 Blu-ray Laser Diode는 전류-전압 관계로부터 미분저항이 변화하게 되는데 이러한 미분저항이 기록품질에 미치는 영향에 대해 분석하고 개선하는 방법을 제안한다.

• Advanced Composite Materials
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• 제18권2호
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• pp.121-134
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• 2009

The present study investigated, both experimentally and numerically, the improvement of low-velocity impact damage resistance of carbon fiber reinforced plastic (CFRP) laminates due to through-the-thickness stitching. First, we conducted drop-weight impact tests for stitched and unstitched laminates. The results of damage inspection confirmed that stitching did improve the impact damage resistance, and revealed that the improvement effect became greater as the impact energy increased. Moreover, the stitching affected the through-the-thickness damage distribution. Next, we performed FEM analysis and calculated the energy release rate of the delamination crack using the virtual crack closure technique (VCCT). The numerical results revealed that the stitching affected the through-the-thickness damage distribution because the stitch threads had a marked effect on decreasing both the modes I and II energy release rate around the bottom of the laminate. Comparison of the results for models that contained delaminations of various sizes revealed that the energy release rate became lower as delamination size increased; therefore the stitching improved the impact resistance more effectively when the impact energy was higher.