• Entomological Research
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• v.48 no.5
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• pp.400-404
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• 2018

In this study, we investigated resistance to the organophosphates chlorpyrifos in Tunisian populations of Culex pipiens pipiens. Three field populations were collected from Northern and central Tunisia between 2003 and 2005 and used for the bioassays tests. Our results registered moderate and high levels of resistance to chlorpyrifos which ranged from 33.8 to 111. The chlorpyrifos resistant populations were highly resistant to propoxur indicated an insensitive acetylcholinesterase 1 (AChE 1). The highest frequency of AChE 1 resistant phenotypes (64%) was recorded in the most resistant population (sample # 1). Bioassays conducted in the presence of synergists showed that not esterases were involved as the resistance mechanism to chlorpyrifos. However, CYP450 was partly involved in the resistance of the most resistant sample (# 1). Starch electrophoresis showed that three esterases were present in studied samples: A2-B2, A4-B4 and B12. Results are discussed in relation to the selection pressure caused by insecticide treatments.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.5
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• pp.278-286
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• 2020

Reynolds-averaged Navier-Stokes simulations have been performed to investigate an effect of numerical region with high resolution for Kelvin wave around KRISO container ship on its resistance. In the present study, 13 millions cells were used to describe wave profile along the ship hull and Kelvin wave patterns. In order to control a size of numerical region with high resolution for waves around the hull, we employed relaxation zones from a side boundary of numerical domain in which Kelvin wave was suppressed. When the far-field Kelvin wave was not precisely resolved due to the relaxation zone, the instantaneous history of ship resistance was affected although the time average of ship resistance showed -1.15~2.1 % errors. Especially, the damping characteristics of ship resistance in time history was significant when using a large relaxation zone in the side boundary.

• Journal of Korean Association for Spatial Structures
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• v.23 no.2
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• pp.61-68
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• 2023

A two-hour fire-resistance PC hollow slab for residential use was developed to secure structural and fire-resistance performance and to be applied to the general building and apartment housing markets. Compared to the existing hollow slab, in order to secure the same or better structural performance and economic feasibility by reducing the quantity, it was attempted to secure the fire resistance performance by reducing the concrete filling rate in the cross section and adjusting the thickness of the upper and lower flanges by optimizing the hollow shape in the cross section of the slab. For structural performance evaluation, experiments were performed on PC hollow slabs by varying the member thickness and the presence or absence of overlaid concrete, and all of the experimental results showed that the design strength was sufficiently exhibited and that stability during construction was possible. The developed synthetic PC hollow slab has secured fire resistance and residential performance so that it can be applied to all buildings, and it is intended to be immediately applied to the field.

• Corrosion Science and Technology
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• v.22 no.6
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• pp.399-407
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• 2023

This study investigated the formation of oxide films on 6061 aluminum (Al) alloy and their impacts on corrosion resistance efficiency by regulating anodization voltage. Despite advantageous properties inherent to Al alloys, their susceptibility to corrosion remains a significant limitation. Thus, enhancing corrosion resistance through developing protective oxide films on alloy surfaces is paramount. The first anodization was performed for 6 h with an applied voltage of 30, 50, or 70 V on the 6061 Al alloy. The second anodization was performed for 0.5 h by applying 40 V after removing the existing oxide film. Resulting oxide film's shape and roughness were analyzed using field emission-scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). Wettability and corrosion resistance were compared before and after a self-assembled monolayer (SAM) using an FDTS (1H, 1H, 2H, 2H-Perfluorodecyltrichlorosilane) solution. As the first anodization voltage increased, the final oxide film's thickness and pore diameter also increased, resulting in higher surface roughness. Consequently, all samples exhibited superhydrophilic behavior before coating. However, contact angle after coating increased as the first anodization voltage increased. Notably, the sample anodized at 70 V with superhydrophobic characteristics after coating demonstrated the highest corrosion resistance performance.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.277.1-277.1
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• 2016

We report on synthesis of large-area MoS2 using chemical vapor deposition (CVD). Relatively uniform MoS2 are obtained. To fabricate field-effect transistor (FET) devices, MoS2 films are transferred to another SiO2/Si substrate using polystyrene (PS) and patterned using oxygen plasma. In addition, to reduce contact resistance, synthesis of graphene used as channel. Device characteristics are presented and compared with the reported results.

• KSBB Journal
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• v.6 no.3
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• pp.223-230
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• 1991

Using the shuttle vector pECCGl between Escherichia coli and Corynebacterium glutamicum and C. glutamicum strain JS231 grown in the medium supplemented with penicillin-G, which inhibits the formation of cross-links in the peptidoglycan of bacterial cell wall, various parameters involved in electroporation system including resistance, electric field strength, capacitance, DNA concentration, and cell density were investigated independently and optimized for the high efficiency transformation of coryneform bacteria. Using cells grown with 0.3U/ml of penicillin-G and harvested at A600 of 0.7-0.8, transformation efficiencies of 107-l08 transformants/$\mu\textrm{g}$ of DNA with Corynebcctertum glutamicum strain JS231 and wild type ATCC13032 were achieved under conditions of 12.5kV/cm of electric field strength, 400 ohms of resistance, $25\mu$F of capacitance, 3$\times$108 cells per transformation(1.2$\times$1010 cells/ml) and 100ng of plasmid DNA per transformation.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.285-291
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• 1998

During recent years, the durability of concrete structures has been considered in concret practice and material research. To preserve the brittleness of concrete as well as energy absorption and impact resistance, amount of fiber usage has greatly increased in the field of public works. Ultra fine powder, silica fume, mixed into concrete, it reduce void of concrete structure. Especially, there's a great effect for strength improvement of concrete by initial pozzolanic reactions. For these reasons, if silica fume mixed into concrete, it decrease the total void by microfilter effect . Pozzolan reaction, between cement particle and silica powder, can elaborate the micro structure of matrix. And so, in this paper, we deal SFRC for the purpose of efficiently using of industrial by-products(silica fume). Also we performed the test for durability such as freeze-thaw resistance and accelerated carbonation of SFRC using silica fume.

• Korean Journal of Weed Science
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• v.32 no.3
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• pp.170-173
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• 2012

China is one of most important countries for production and consumption of herbicide. Although the chemical weeding technology promoted the development of agricultural modernization in Chinese, it led to the negative effects to agriculture. In particular, the weeds resistant herbicide in paddy field had been serious challenge for safe production of rice. The chemical control technology for weed resistant herbicide with effective, low cost and safety characteristic will be key problem being solved in futhure.

• Biomedical Science Letters
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• v.11 no.3
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• pp.295-299
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• 2005

Staphylococcus aureus is an important animal and human pathogen implicated in a variety of disease including food-poisoning caused by staphyloccal enterotoxins (SEs). In order to investigate the difference in genomic types and to monitor the transmission of S. aureus isolates, a total of 25 S. aureus isolates from different sources were determined for their genotypic characteristics by pulsed-field gel electrophoresis (PFGE) in addition to their ability to enterotoxin production and antibiotic resistance patterns in this study. All the isolates were susceptible to amikacin, and the resistance pattern to ampicillin and penicillin were most common among 14 different patterns. Eleven of 24 isolates produced one of three SEs, SEA, SEC or SED. Sixteen representative PFGE patterns were obtained by Smal restriction fragments of S. aureus isolates. Analysis of dendrogram based on PFGE band patterns suggested that food-poisoning outbreaks be caused by the diverse sources of food, of which their raw materials were infected with S. aureus. Also, it could be concluded that PFGE was a powerful tool for epidemiological tracing of infection source for food-initiated outbreaks.

• 전기의세계
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• v.22 no.3
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• pp.25-34
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• 1973

In this paper, the characteristics of a single phase induction motor which is considered the space harmonic flux by the double revolving field theory is analysed. As the rotor resistance for the fundamental flux is separated from the resistance for the rotor bar and end-ring, and the rotor leakage reactnace is separated from the skew leakage reactance and the other, so the circuit constants for the space harmonic flux is expressed by the circuit constants for the fundamentals. As the ratio of the circuit constants for the magnetizing reactance is used, the generalized equivalent circuit is made up. the characteristic equation which is able to analysis the subdivided characteristics by the above circuit is induced. The ratio of the circuit constants and the skew angle being changed, the variations of the torque-speed characteristics for the fundamentals and harmonics is examined by this equation.