• Title/Summary/Keyword: Well resistance

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A Study on Consolidation Characteristics by Considering the Initial Radial Compression at Sand Pile Adjacent Ground (샌드파일 주변지반에서 초기 방사방향 압축에 의한 압밀특성 연구)

  • 천병식;여유현
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.11a
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    • pp.649-656
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    • 2000
  • Consolidation of the ground surrounding the sand piles is delayed by well resistance and smear effect. This study is executed to understand the factors that affect the characteristics of consolidation. This was accomplished by utilizing the estimated and measured values of the soil properties through the monitoring of the ground surrounding the sand piles. When it is assumed that the horizontal coefficient is equal to the vertical coefficient of consolidation, the estimated values is exceedingly similar to the measured values. The properties of the initially disturbed soil by the sand pile installation seemed to improve through the process of consolidation with the passage of time. From the results of the analysis of the settlement measurement, the measured values occurred about 60~90% of the predicted values. Considering the initial radical compression deformation, according to the theory of cavity expansion, the difference between the two appears to be in good agreement. In this study, to understand the behavioral characteristics of the ground surrounding the sand piles requires estimation through considering the initial radial compression as well as smear effect of the soil disturbance and well resistance.

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Cooperative Interaction between Acid and Copper Resistance in Escherichia coli

  • Kim, Yeeun;Lee, Seohyeon;Park, Kyungah;Yoon, Hyunjin
    • Journal of Microbiology and Biotechnology
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    • v.32 no.5
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    • pp.602-611
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    • 2022
  • The persistence of pathogenic Escherichia coli under acidic conditions poses a serious risk to food safety, especially in acidic foods such as kimchi. To identify the bacterial factors required for acid resistance, transcriptomic analysis was conducted on an acid-resistant enterotoxigenic E. coli strain and the genes with significant changes in their expression under acidic pH were selected as putative resistance factors against acid stress. These genes included those associated with a glutamate-dependent acid resistance (GDAR) system and copper resistance. E. coli strains lacking GadA, GadB, or YbaST, the components of the GDAR system, exhibited significantly attenuated growth and survival under acidic stress conditions. Accordantly, the inhibition of the GDAR system by 3-mercaptopropionic acid and aminooxyacetic acid abolished bacterial adaptation and survival under acidic conditions, indicating the indispensable role of a GDAR system in acid resistance. Intriguingly, the lack of cueR encoding a transcriptional regulator for copper resistance genes markedly impaired bacterial resistance to acid stress as well as copper. Conversely, the absence of YbaST severely compromised bacterial resistance against copper, suggesting an interplay between acid and copper resistance. These results suggest that a GDAR system can be a promising target for developing control measures to prevent E. coli resistance to acid and copper treatments.

Electrically Programmable Fuse - Application, Program and Reliability (전기적 프로그램이 가능한 퓨즈 - 응용, 프로그램 및 신뢰성)

  • Kim, Deok-Kee
    • Journal of the Microelectronics and Packaging Society
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    • v.19 no.3
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    • pp.21-30
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    • 2012
  • Technology trend and application of laser fuse, anti-fuse, and eFUSE as well as the structure, programming mechanism, and reliability of eFUSE have been reviewed. In order to ensure eFUSE reliability in the field, a sensing circuit trip point consistent with the fuse resistance distribution, process variation, and device degradation in the circuit such as hot carrier or NBTI, as well as fuse resistance reliability must be considered to optimize and define a reliable fuse programming window.

Structural performance of unprotected concrete-filled steel hollow sections in fire: A review and meta-analysis of available test data

  • Rush, David;Bisby, Luke;Jowsey, Allan;Melandinos, Athan;Lane, Barbara
    • Steel and Composite Structures
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    • v.12 no.4
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    • pp.325-350
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    • 2012
  • Concrete filled steel hollow structural sections (CFSs) are an efficient, sustainable, and attractive option for both ambient temperature and fire resistance design of columns in multi-storey buildings and are becoming increasingly common in modern construction practice around the world. Whilst the design of these sections at ambient temperatures is reasonably well understood, and models to predict the strength and failure modes of these elements at ambient temperatures correlate well with observations from tests, this appears not to be true in the case of fire resistant design. This paper reviews available data from furnace tests on CFS columns and assesses the statistical confidence in available fire resistance design models/approaches used in North America and Europe. This is done using a meta-analysis comparing the available experimental data from large-scale standard fire tests performed around the world against fire resistance predictions from design codes. It is shown that available design approaches carry a very large uncertainty of prediction, suggesting that they fail to properly account for fundamental aspects of the underlying thermal response and/or structural mechanics during fire. Current North American fire resistance design approaches for CFS columns are shown to be considerably less conservative, on average, than those used in Europe.

Antimicrobial Resistance of Clinically Important Bacteria Isolated from Burn Wound Infections in Children (화상감염 소아환자에서 분리된 주요 균종에 대한 항생제의 내성률)

  • Kang, Joo Yeon;Shin, Hea Soon
    • Korean Journal of Clinical Pharmacy
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    • v.23 no.1
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    • pp.20-25
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    • 2013
  • Background & Objectives: Burn injury mortality and septic complication are frequent and well-known in burned pediatric patients. The overuse of antibiotics is the base for development of wound infection by resistant microorganisms as well as opportunist agents. Methods: We have carried out a study of the bacterial profile and antimicrobial resistance clinically important bacteria isolated from burn wound infections in children patients. The most common isolate from burn wound cultures was Pseudomonas aeruginosa (26.8%), followed by Staphylococcus aureus (25.4%), Acinetobacter baumannii (12.7%), coagulase negative staphylococcus (12.0%), Enterococcus faecium (7.7%), Escherichia coli (4.9%), Enterococcus faecalis (3.7%), Burkholderia cepacia (3.0%), Enterobacter cloacae (2.3%) and Klebsiella pneumonia (2.3%). Colistin was very significantly effective drug in gram negative organism, such as Pseudomonas aeruginosa and Acinetobacter baumannii. Results & Conclusion: The resistance rates were 65% and 98% to piperacillin, 63% and 97% to ceftazidime, 28% and 50% to levofloxacin. The most effective antibiotic in gram positive organism, such as Staphylococcus aureus, coagulase negative staphylococcus were moxifloxacin. The resistance rates were 83% and 64% to ciprofloxacin, 80% and 17% to clindamycin.

Improvement of prediction methods of power increase in regular head waves using calm-water and resistance tests in waves

  • Chun, Ho-Hwan;Lee, Cheol-Min;Lee, Inwon;Choi, Jung-Eun
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.13 no.1
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    • pp.278-291
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    • 2021
  • This paper applies load variation method to predict speed-power-rpm relationship along with propulsive performances in regular head waves, and to derive overload factors (ITTC, 2018). 'Calm-water tests' and 'resistance test in waves' are used. The modified overload factors are proposed taking non-linearity into consideration, and applied to the direct powering, and resistance and thrust identity method. These indirect methods are evaluated through comparing the speed-power-rpm relationships with those obtained from the resistance and self-propulsion tests in calm water and in waves. The objective ship is KVLCC2. The load variation method predicts well the speed-power-rpm relationship and propulsion performances in waves. The direct powering method with modified overload factors also predicts well. The resistance and thrust identity method with modified overload factor predicts with a little difference. The direct powering method with overload factors predicts with a relatively larger difference.

Evaluation of the Characteristics of the Aluminum Alloy Casting Material by Heat Treatment (AC8A 알루미늄합금 주조재의 열처리에 의한 특성 평가)

  • Lee, Syung Yul;Park, Dong Hyun;Won, Jong Pil;Kim, Yun Hae;Lee, Myung Hoon;Moon, Kyung Man;Jeong, Jae Hyun
    • Corrosion Science and Technology
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    • v.11 no.6
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    • pp.280-285
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    • 2012
  • Aluminum is on active metal, but it is well known that its oxide film plays a role as protective barrier which is comparatively stable in air and neutral aqueous solution. Thus, aluminum alloys have been widely applied in architectural trim, cold & hot-water storage vessels and piping etc., furthermore, the aluminum alloy of AC8A have been widely used in mold casting material of engine piston because of its properties of temperature and wear resistance. In recent years, the oil price is getting higher and higher, thus the using of low quality oil has been significantly increased in engines of ship and vehicle. Therefore it is considered that evaluation of corrosion resistance as well as wear resistance of AC8A material is also important to improve its property and prolong its lifetime. In this study, the effect of solution and tempering heat treatment to corrosion and wear resistance is investigated with electrochemical method and measurement of hardness. The hardness decreased with solution heat treatment compared to mold casting condition, but its value increased with tempering heat treatment and exhibited the highest value of hardness with tempering heat treatment temperature at $190^{\circ}C$ for 24hrs. Furthermore, corrosion resistance increased with decreasing of the hardness, and decreased with increasing of the hardness reversely. As a result, it is suggested that the optimum heat treatment to improve both corrosion and wear resistance is tempering heat treatment temperature at $190^{\circ}C$ for 16hrs.

Genetic Mapping of a Resistance Locus to Phytophthora sojae in the Korean Soybean Cultivar Daewon

  • Jang, Ik-Hyun;Kang, In Jeong;Kim, Ji-Min;Kang, Sung-Taeg;Jang, Young Eun;Lee, Sungwoo
    • The Plant Pathology Journal
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    • v.36 no.6
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    • pp.591-599
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    • 2020
  • Phytophthora root and stem rot reduce soybean yields worldwide. The use of R-gene type resistance is currently crucial for protecting soybean production. The present study aimed to identify the genomic location of a gene conferring resistance to Phytophthora sojae isolate 2457 in the recombinant inbred line population developed by a cross of Daepung × Daewon. Singlemarker analysis identified 20 single nucleotide polymorphisms associated with resistance to the P. sojae isolate 2457, which explained ~67% of phenotypic variance. Daewon contributed a resistance allele for the locus. This region is a well-known location for Rps1 and Rps7. The present study is the first, however, to identify an Rps gene locus from a major soybean variety cultivated in South Korea. Linkage analysis also identified a 573 kb region on chromosome 3 with high significance (logarithm of odds = 13.7). This genomic region was not further narrowed down due to lack of recombinants within the interval. Based on the latest soybean genome, ten leucine-rich repeat coding genes and four serine/ threonine protein kinase-coding genes are annotated in this region, which all are well-known types of genes for conferring disease resistance in crops. These genes would be candidates for molecular characterization of the resistance in further studies. The identified R-gene locus would be useful in developing P. sojae resistant varieties in the future. The results of the present study provide foundational knowledge for researchers who are interested in soybean-P. sojae interaction.

Contact resistance increment of no-insulation REBCO magnet during a quench

  • Im, Chaemin;Cho, Mincheol;Bang, Jeseok;Kim, Jaemin;Hahn, Seungyong
    • Progress in Superconductivity and Cryogenics
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    • v.21 no.1
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    • pp.31-35
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    • 2019
  • The lumped-parameter circuit model for a no- insulation (NI) high temperature superconductor (HTS) magnet has been well understood after many experimental and analytic studies over a decade. It successfully explains the non-linear charging behaviors of NI magnets. Yet, recently, multiple groups reported that the post-quench electromechanical behaviors of an NI HTS magnet may not be well explained by the lumped circuit model. The characteristic resistance of an NI magnet is one of the key parameters to characterize the so-called "NI behaviors" of an NI magnet and recently a few groups reported a potential that the characteristic resistance of an NI magnet may substantially vary during a quench. This paper deals with this issue, the increment of contact resistance of the no-insulation (NI) REBCO magnet during a quench and its impact on the post-quench behaviors. A 7 T 78 mm NI REBCO magnet that was previously built by the MIT Francis Bitter Magnet Laboratory was chosen for our simulation to investigate the increment of contact resistance to better duplicate the post-quench coil voltages in the simulation. The simulation results showed that using the contact resistance value measured in the liquid nitrogen test, the magnitude of the current through the coil must be much greater than the critical current. This indicates that the value of the contact resistance should increase sharply after the quench occurs, depending on the lumped circuit model.

National Measurement Standard of Electrical Resistance using a Room Temperature Resistance Bridge (실온 저항브리지를 이용한 전기저항 측정의 국가표준 기술)

  • Yu, Kwang-Min;Park, Young-Tae;Kang, Jean-Hong;Kim, Han-Jun;Ihm, G.
    • Proceedings of the KIEE Conference
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    • 2002.07b
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    • pp.669-672
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    • 2002
  • Establishment of the Quantum Hall Resistance(QHR) Standard as national resistance standard using a room temperature DCC resistance bridge is described. A simple method are used to obtain the current dependence and error of 10: 1 ratio of the bridge instead of the method using a cryogenic resistance bridge. Measurement uncertainty of the system is estimated as $0.14{\times}10^{-6}$ and it is confirmed that the QHR standard is agreed well with the QHR of other NMIs using the cryogenic resistance bridge within the uncertainty, More improvement about performance of the QHR device and 10: 1 ratio accuracy is still under progress.

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