• 멤브레인
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• 제8권3호
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• pp.130-137
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• 1998

막결합형 활성슬러지 시스템의 운전에서 운전 시간에 따른 막 여과 특성의 변화를 살펴보았다. 슬러지의 순환 과정에서 전단력에 의한 플럭 크기의 변화가 여과 저항에 미치는 영향을 살펴보기 위해 여과 저항 모델식을 사용하였으며 또한 케이크 층의 특성 변화를 살펴보기 위해 입자의 비저항을 측정하였다. 플럭의 크기는 운전 초기 4~6시간 내에 급격한 감소 양상을 보였으며 이후 서서히 감소하여 20$\mu$m 부근의 값을 유지하였다. 운전 시간에 따른 입자의 비저항의 증가는 시간에 따른 입자 크기의 감소로부터 예상되는 결과와 잘 일치하였다. 플럭의 구성 성분 중에서 용존 유기물과 미생물이 플럭스 감소에 미치는 영향은 상대적으로 작았으며 콜로이드성 입자가 가장 큰 플럭스 감소 요인으로 작용하였다. 미생물 플록과 비교하여 콜로이드성 입자는 높은 비저항을 가졌으며 이로 인해 상대적으로 높은 케이크 저항을 나타내었다.

• 동력기계공학회지
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• 제6권1호
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• pp.74-81
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• 2002

The characteristics of corrosion resistance for the surface of ductile cast iron(GCD40) by plasma nitriding process have been studied in terms of electrochemical polarization behaviors including corrosion potential($E_{corr}$), anodic polarization trends, polarization resistance($R_p$), and also have been studied microstructures, hardness and specific wear of nitrided layer Nitrided layer showed an enhanced hardness values in all the plasma nitriding condition investigated. In the result of wear test, specific wear of nitrided specimens were much decreased than that of non-treated specimens. In the results of XRD, ${\gamma}'phase\;and\;{\varepsilon}$ phase were detected in nitrided surface. And it was found that ${\varepsilon}$ phase was decreased and ${\gamma}'phase$ was increased respectively, as the nitriding time became longer. In the test of corrosion resistance, natural potentials in all the nitrided specimens were towards noble directions than in the case of non-treated specimens. The measurement of electrode potentials revealed that corrosion resistivity of plasma nitrided specimens were higher than in the case of the non-treated specimens.

• 한국생산제조학회지
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• 제19권1호
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• pp.128-133
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• 2010

The Titanium has many superior characteristics which are specific strength, heat resistance, corrosion resistance, organism compatibility, non-magnetic and etc. and their quantity are abundant. this study performed turning operation of Ti-6Al-4V alloy using the TiAlN Coated Tool which treated Physical Vapor Deposition. Experimental works are also executed to measure cutting force, tool wear, chip figuration and surface roughness for different cutting conditions. As a result of study. Cutting depth influences on the cutting force much more than the feed rate and the value of the cutting force is the most stable at the depth of 1.0mm. And tool wear was serious at over 100m/min of cutting speed and cutting condition was excellent at 1.0mm of cutting depth.

• The Plant Pathology Journal
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• 제38권6호
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• pp.616-628
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• 2022

Resistance to pyraclostrobin due to a single nucleotide polymorphism at 143rd amino acid position on the cytochrome b gene has been a major source of concern in red pepper field infected by anthracnose in Korea. Therefore, this study investigated the response of 24 isolates of C. acutatum and C. gloeosporioides isolated from anthracnose infected red pepper fruits using agar dilution method and other molecular techniques such as cytochrome b gene sequencing, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and allele-specific polymerase chain reaction (PCR). The result showed that four isolates were resistant to pyraclostrobin on agar dilution method and possessed GCT (alanine) codon at 143rd amino acid position, whereas the sensitive isolates possessed GGT (glycine). Furthermore, this study illustrated the difference in the cytochrome b gene structure of C. acutatum and C. gloeosporioides. The use of cDNA in this study suggested that the primer Cacytb-P2 can amplify the cytochrome b gene of both C. acutatum and C. gloeosporioides despite the presence of various introns in the cytochrome b gene structure of C. gloeosporioides. The use of allele-specific PCR and PCR-RFLP provided clear difference between the resistant and sensitive isolates. The application of molecular technique in the evaluation of the resistance status of anthracnose pathogen in red pepper provided rapid, reliable, and accurate results that can be helpful in the early adoption of fungicide-resistant management strategies for the strobilurins in the field.

• The Plant Pathology Journal
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• 제20권1호
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• pp.22-29
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• 2004

Many important horticultural and field crops are susceptible to virus infections or may possess a degree of resistance to some viruses, but become infected by others. Plant viruses enter cells through the presence of wounds, and replicate intracellularly small genomes that encode genes required for replication, cell-to-cell movement and encapsidation. There are numerous evidences from specific virus-host interactions to require the involvement of host factors and steps during viral replication cycle. However, viruses should deal with host defense responses either by general or specific mechanisms, targeting viral components or genome itself. On the other hand, the host plants have also adapted to defend themselves against viral attack by operating different lines of resistance responses. The defense-related interactions provide new insights into the complex molecular strategies for hosts for defense and counter-defense employed by viruses.

• 전기의세계
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• 제22권6호
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• pp.33-51
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• 1973

To lower the earth resistance shall be one of the most effective method for the prevention of lightening damage on power transmission line. In this report, in order to investigate various characteristic necessary to lowering the earth resistance, the following experiments have been made at 154KV U1San-PoHang T/L, 154KV YoSu-SoonChun T/L and so on. 1. Measurement of Earth specific resistance, 2. Efficiency of Earthing of concrete foundation for steel structure., 3. Efficiency of Earthing with counter poise., 4. Compound impulse test with foundation of steel structure and counter poise. With the above investigate a guidance have been prepared for the effective work-performance of steel structure.

• Journal of Welding and Joining
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• 제17권5호
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• pp.77-82
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• 1999

Resistance spot welding process is completed in very short time and there are many factors affecting on the generation of heat. It is difficult to control these experimental factors and monitor distribution of the temperature and stresses in the experimental analysis case. and too much time and expense are required for the experimental trials to fine proper welding condition. So numerical analyses have been attempted steadily, but most numerical analyses on the resistance spot welding are mainly focused on thermal behavior. Therefore, in this paper, the numerical analysis of mechanical behavior as well as heat conduction is carried out for the spot welding process. For this numerical analysis, axial symmetric computer program for the spot welding analysis by F.E.M. has been developed considering heat conduction and thermal elastic-plastic theory. Material properties depending on temperature such as density, heat conductivity, heat expansion coefficient, specific heat, yield stress, elastic modulus, and specific resistance are considered. Using the results of temperature distribution obtained from heat conduction analysis, the thermal elastic-plastic analysis is carried out to clarify mechanical behavior of spot welded specimen. In order to evaluate the effect of residual stresses, numerical analyses are carried out under tension-shear load in two cases respectively; one with residual stress, the other without residual stresses.

• 전기전자학회논문지
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• 제20권2호
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• pp.181-183
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• 2016

탄화규소(Silicon Carbide) 기반의 1200 V급 Merged Pin Schottky(MPS) 다이오드의 구조를 2D-atlas simulation tool을 사용하여 최적화 및 설계하였다. 최적화된 항복전압과 온-저항 값을 얻기 위해 본 소자에서 중요한 파라미터인 P-Grid의 도핑농도와 에피층의 도핑농도를 각각 $2{\sim}10{\times}10^{17}cm^{-3}$, $2{\sim}10{\times}10^{16}cm^{-3}$으로 변화시키면서 소자의 전기적 특성을 분석하였으며, 그 후 P-Grid의 Space값을 $1{\sim}5{\mu}m$로 설계하여 이에 따른 항복전압과 온-저항의 값을 확인하였다. 항복전압과 온-저항은 서로 trade-off 관계에 있기 때문에 각 변수에서 도출된 값들을 Baliga's Figure Of Merit (BFOM)식에 대입하여 비교하였다. 그 결과 고전압 소자에 적용 가능한 1200 V급 4H-SiC MPS다이오드를 최적화 및 설계를 도출하였다.

• ETRI Journal
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• 제26권1호
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• pp.7-13
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• 2004

To improve the characteristics of breakdown voltage and specific on-resistance, we propose a new structure for a LDMOSFET for a PDP scan driver IC based on silicon-on-insulator with a trench under the gate in the drift region. The trench reduces the electric field at the silicon surface under the gate edge in the drift region when the concentration of the drift region is high, and thereby increases the breakdown voltage and reduces the specific on-resistance. The breakdown voltage and the specific on-resistance of the fabricated device is 352 V and $18.8 m{\Omega}{\cdot}cm^2$ with a threshold voltage of 1.0 V. The breakdown voltage of the device in the on-state is over 200 V and the saturation current at $V_{gs}=5V$ and $V_{ds}$=20V is 16 mA with a gate width of $150{\mu}m$.

• ETRI Journal
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• 제36권5호
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• pp.829-834
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• 2014

In this paper, a lateral power metal-oxide-semiconductor field-effect transistor with ultra-low specific on-resistance is proposed to be applied to a high-voltage (up to 200 V) integrated chip. The proposed structure has two characteristics. Firstly, a high level of drift doping concentration can be kept because a tilt-implanted p-drift layer assists in the full depletion of the n-drift region. Secondly, charge imbalance is avoided by an extended trench gate, which suppresses the trench corner effect occurring in the n-drift region and helps achieve a high breakdown voltage (BV). Compared to a conventional trench gate, the simulation result shows a 37.5% decrease in $R_{on.sp}$ and a 16% improvement in BV.