• 도시과학
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• 제12권2호
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• pp.13-18
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• 2023

This study investigates the effect of polyvinyl alcohol (PVA) fiber and silica fume addition on the chloride penetration resistance of alkali-activated slag. Silica fume was added to replace slag at the dosage of 0, 5, 10, and 20% by weight of the binder, while PVA fiber was added at the dosage of 0, 1, and 2% by volume of the mixture. Samples were synthesized via alkali activator with 1.0 of silicate modulus and cured at room temperature for 28 days. Compressive strength test, permeable voids volume test, water absorprtion test, and rapid chloride penetration test were conducted for measuring the charaterisitics of alkali-activaed slag. The results showed that increasing silica fume content up to 10% in alkali-activated slag improved compressive strength and chloride penetration resistance. Addition of PVA fibers up to 1% by volume enhanced strength and chloride penetration resistance, but exceeding this led to reduced strength and durability due to increased void formation in the matrix.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1597-1599
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• 2007

In TFT-LCD, mura is a defect which degrades the display quality. The resistance difference between gate lines is the main cause of H-Block mura. Two methods could eliminate this defect. A thinner gate layer or gate fan-out pattern decrease mura level. H-Block mura has been reduced after implementing the new schemes.

• Tribology and Lubricants
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• 제16권4호
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• pp.253-258
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• 2000

Frictional behavior of wire electric discharge machined surfaces of spheroidized annealed STDll steel was investigated. The surfaces were produced with a various series of finish cuts where pulse energy was reduced with increase in the number of finish cuts. Roughness and micro-hardness of the surfaces were also measured. It is observed that the increase in the number of finish cuts produces the surface exhibiting lower frictional resistance followed by higher resistance after considerable wear. Effects of finish cuts on the friction characteristics are discussed with the aid of roughness and micro-hardness of the surfaces.

• International Journal of Korean Welding Society
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• 제1권1호
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• pp.13-16
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• 2001

High speed seam weldability of tin coated steels was investigated. Welding was performed by the laboratory wire seam welder that was equipped with process monitoring system Test results showed that increase in applied current and pressure reduced the total resistance across the welding electrodes. Lower and upper limits of welding current increased as the sheet thickness increased, while the acceptable welding condition range decreased. However, extremely low electrode pressure produced unstable welding condition range. The results also demonstrated that slower welding speeds widened the optimum welding heat input range.

• The Plant Pathology Journal
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• 제32권3호
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• pp.228-241
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• 2016

In our previous study, we reported that a novel endophytic bacterium Bacillus oryzicola YC7007 has suppressed bacterial diseases of rice via induced systemic resistance and antibiotic production. This endophytic strain, B. oryzicola YC7007 was used as a biological control agent against bakanae disease of rice caused by Fusarium fujikuroi, and its mechanism of interaction with the pathogen and the rice was further elucidated. Root drenching with B. oryzicola YC7007 suspension reduced the disease severity of bakanae significantly when compared with the untreated controls. The treatments of B. oryzicola YC7007 suspension ($2.0{\times}10^7cfu/ml$) to the rice rhizosphere reduced bakanae severity by 46-78% in pots and nursery box tests containing autoclaved and non-autoclaved soils. Moreover, in the detached rice leaves bioassay, the development of necrotic lesion and mycelial expansion of F. fujikuroi were inhibited significantly by spraying the culture filtrate of B. oryzicola YC7007. Drenching of ethyl acetate extracts of the culture filtrate to the rhizosphere of rice seedlings also reduced the bakanae disease severity in the plant culture dish tests. With the root drenching of B. oryzicola YC7007 suspension, the accumulation of hydrogen peroxide was observed at an early stage of rice seedlings, and a hormonal defense was elicited with and without pathogen inoculation. Our results showed that the strain B. oryzicola YC7007 had a good biocontrol activity against the bakanae disease of rice by direct inhibition, and was also capable of inducing systemic resistance against the pathogen via primed induction of the jasmonic acid pathway.

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3553-3558
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• 2014

The reduced graphene oxide(rGO)/aluminum phosphate($AlPO_4$)-coated $LiMn_{1.5}Ni_{0.5}O_4$ (LMNO) cathode material has been developed by hydroxide precursor method for LMNO and by a facile solution based process for the coating with GO/$AlPO_4$ on the surface of LMNO, followed by annealing process. The amount of $AlPO_4$ has been varied from 0.5 wt % to 1.0 wt %, while the amount of rGO is maintained at 1.0 wt %. The samples have been characterized by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. The rGO/$AlPO_4$-coated LMNO electrodes exhibit better cyclic performance compared to that of pristine LMNO electrode. Specifically, rGO(1%)/$AlPO_4$(0.5%)- and rGO(1%)/$AlPO_4$(1%)-coated electrodes deliver a discharge capacity of, respectively, $123mAhg^{-1}$ and $122mAhg^{-1}$ at C/6 rate, with a capacity retention of, respectively, 96% and 98% at 100 cycles. Furthermore, the surface-modified LMNO electrodes demonstrate higher-rate capability. The rGO(1%)/$AlPO_4$(0.5%)-coated LMNO electrode shows the highest rate performance demonstrating a capacity retention of 91% at 10 C rate. The enhanced electrochemical performance can be attributed to (1) the suppression of the direct contact of electrode surface with the electrolyte, resulting in side reactions with the electrolyte due to the high cut-off voltage, and (2) smaller surface resistance and charge transfer resistance, which is confirmed by total polarization resistance and electrochemical impedance spectroscopy.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권5호
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• pp.442-455
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• 2016

The resistance and seakeeping performance of a high-speed monohull vessel were investigated through a series of model tests in a towing tank. The hull had a slender wave-piercing bow, round bilge, and small deadrise angle on stern. Tests on the bare hull in calm water were first conducted and tests on spray rails followed. The spray rails were designed to control the flow direction and induce a hydrodynamic lift force on the hull bottom to reduce trim angle and increase rise of the hull. The maximum trim of the bare hull was $4.65^{\circ}$ at the designed speed, but the spray rails at optimum location reduced trim by $0.97^{\circ}$. The ship motion in head seas was examined after the calm water tests. Attaching the rails on the optimum location effectively reduced the pitch and heave motion responses. The vertical acceleration at the fore perpendicular reduced by 11.3%. The effective power in full scale was extrapolated from the model test results and it was revealed that the spray rails did not have any negative effects on the resistance performance of the hull, while they effectively stabilized the vessel in calm water and waves.

• 수산해양기술연구
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• 제22권1호
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• pp.1-5
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• 1986

In order to improve the net-mouth height of dragged gears, the authors devised models of floatingcollars of nylon cloth instead of floats and experimented with 4 types-A type (length 65em, breadth 3em), B type (length 65em, breadth 4em), C type (length 65em, breadth 5em) and D type (length 65 em, breadth 6em) attached respectively to the front edge of square of a model net after preliminary experimentation. These various types of floating collars were experimented in a circulating water channel to evaluate the characteristics of net-mouth height and hydrodynamic resistance and the effect of the length of bridles were also examined. The results obtained were as follows: 1. In case of attaching floats, the model net-mouth height reduced from 80 em to 20 em when current velocity was increased from 0.25m/see to 1m/sec. 2. In case of attaching floating collars, the model net-mouth heights were maintained 70 em, 71 em, 80 em, 78 em in maximum and 55 em, 63 em, 69 em, 73 em in minimum respectively even the current volocity was increased from 0.25 m/see to 1 m/see. 3. The model net-mouth height was reduced to 10 em maximum according to the current velocity and types of floating collars when the bridles were shortened 3~4 mm in length. 4. Hydrodynamic resistance of D type only was increased to 700 g in maximum and those of A, B, C type were reduced to 460 g in maximum at current velocity beyond 0.5 m/ see when bridles were shortened 3-4 mm in length. 5. But the model net-mouth heights became higher in accordance with breadth of floating coliars, B type was the best for this model net in case that hydrodynamic resistance was taken into account.

• Journal of Microbiology and Biotechnology
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• 제18권11호
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• pp.1853-1857
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• 2008

Salmonella contamination in chicken meat was studied with 100 chicken meat samples purchased from 55 shops located in various regions. A total of 21 isolates of Salmonella enterica were isolated from 21 chicken meat samples from four shops located at open markets, whereas there were none from supermarkets with well-equipped cold systems. Among these, 18 isolates were identified as Salmonella enterica serotype Haardt (S. Haardt) and three isolates were S. enterica serotype Muenchen. When the minimal inhibitory concentrations of the S. Haardt isolates were assayed with the agar dilution method to determine susceptibility to ampicillin, chloramphenicol, sulfisoxazole, tetracycline, and nalidixic acid, all 18 isolates were resistant to tetracycline and nalidixic acid and nine of these were resistant to ampicillin. These isolates showed reduced susceptibility to eight fluoroquinolones including ciprofloxacin, enrofloxacin, levofloxacin, gatifloxacin, gemifloxacin, moxifloxacin, norfloxacin, and ofloxacin. When quinolone resistance determining regions of gyrA and gyrB were sequenced, every isolate had the same missense mutation Ser83$\rightarrow$Tyr (TCC$\rightarrow$+TAC) in gyrA, whereas no mutation was found in gyrB. Pulsed-field gel electrophoresis with XbaI revealed a close relationship among these isolates, suggesting a contamination of raw chicken meat with clonal spread of nalidixic acid-resistant and quinolone-reduced susceptibility S. Haardt in chickens. Results in this study show the importance of a well-equipped cold system and the prudent use of fluoroquinolone in chickens to prevent the occurrence of quinolone-resistant isolates.

• Archives of Pharmacal Research
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• 제21권6호
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• pp.671-676
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• 1998

Five hundred and seventy clinical strains of Pseudomonas aeruginosa were isolated from August 1993 to August 1994 in Korea and screened for their resistance to ciprofloxacin, norfloxacin, and ofloxacin. Among these, two P. aeruginosa strains (PA150 and PA300) were selected based on their strong resistance (MICs > 50mcg/ml) to all three quinolones. The susceptible strain as well as two resistant strains had proton gradient-dependent efflux system. Efflux system in PA300 showed different specificities to ofloxacin and ciprofloxacin while PA150 had less permeability for ofloxacin. Ofloxacin had a less inhibitory action on DNA synthesis in permeabilized cells of PA150 and PA300 than 1771M. When quinolone resistance determining region (QRDR) in gyrA was sequenced, PA300 had one missense mutation, Asn 116Tyr, which was newly reported in this work. The results showed that PA150 became ofloxacin resistant by reduced ofloxacin accumulation due to the existence of efflux system and low permeability, while resistance of PA300 was due to the efflux system and a mutation in QRDR of gyrA -the target site of quinolone.