• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.166-167
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• 2019

In this study, to test the performance of concrete used as a concrete admixture as a recycling method of CGS, gypsum was mixed and the chloride ion penetration resistance test of CGS and BFS substituted concrete was conducted. As a result, it was found that without gypsum type test specimen, the CGS sustituted test specimens had lower chloride ion penetration resistance than the BFS substituted specimens. When gypsum was added, it was confirmed that the chloride ion penetration resistance was poor regardless of the type of admixture. In addition, it was confirmed that both admixtures were less resistant to chloride ion penetration than OPC, regardless of the presence of gypsum. However, considering the uneven quality variation of coal, which greatly affects the quality of CGS, further research is needed.

• Transactions on Electrical and Electronic Materials
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• v.12 no.6
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• pp.245-248
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• 2011

The scaling down of metal oxide semiconductor field-effect transistors (MOSFETs) for the last several years has contributed to the reduction of the scaling variables and device parameters as well as the operating voltage of the MOSFET. At the same time, the variation in the electrical characteristics of MOSFETs is one of the major issues that need to be solved. Especially because the issue with variation is magnified as the drive voltage is decreased. Therefore, this paper will focus on the variations between electrical characteristics and drain voltage. In order to do this, the test patterned multi-finger MOSFETs using 90-nm process is used to investigate the characteristic variations, such as the threshold voltage, DIBL, subthreshold swing, transconductance and mobility via parasitic resistance extraction method. These characteristics can be analyzed by varying the gate width and length, and the number of fingers. Through this modeling scheme, the characteristic variations of multi-finger MOSFETs can be analyzed.

• Bulletin of the Society of Naval Architects of Korea
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• v.22 no.2
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• pp.35-48
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• 1985

The present work develops a method of evaluating thrust deduction and wake for different loads of the propeller using the concerted application of the theoretical tools and experimental techniques. It also shows the applicability of the new method to the design of optimum hull form. Firstly, the problem of hull-propeller interaction was analyzed in terms of inviscid as well as viscous components of the thrust deduction and wake. The wavemaking resistance of a hull and propeller were mathematically represented by sources on the hull surface and sink on the propeller plane, respectively. The strength of sink was determined by utilizing the radial distributions of propeller load and nominal wake. The resistance increment due to a propeller and the axial perturbation flow induced by the hull in the propeller plane were calculated. Especially, the inviscid component of the thrust deduction was calculated by subtraction the wavemaking resistance of a bare hull, the wavemaking resistance of a free-running propeller and the augmentation of propeller resistance due to hull action from the wavemaking resistance of the hull with a propeller. The viscous components of the thrust deduction and wake were estimated as functions of propeller load which were established by the propeller load varying test after deduction the calculated inviscid components. Secondly, an analysis method of powering performance was developed based on the potential theory and the propeller load varying test. The hybrid method estimates the thrust deduction, wake and propeller open-water efficiency for different propeller load. This method can be utilized in the analysis of powering performance for the propeller load variation such as the added resistance due to hull surface roughness, the added resistance due to wind, etc. Finally, the hybrid method was applied to the optimum design of hull form. A series of afterbody shapes was obtained by systematically varying the waterplane and section shapes of a parent afterbody without changing the principal dimensions, block coefficient and prismatic coefficient. From the comparison of the predicted results such as wavemaking resistance, thrust deduction, wake and delivered power, an optimum hull form was obtained. The delivered power of the optimized hull form was reduced by 5.7% which was confirmed by model tests. Also the predicted delivered power by the hybrid method shows fairly good agreement with the test result. It is therefore considered that the new analysis method of powering performance can be utilized as a practical tool for the design of optimum hull form as for the analysis of powering performance for the propeller load variation in the preliminary design stage.

• Tribology and Lubricants
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• v.12 no.4
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• pp.28-34
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• 1996

The lubrication characteristics of high-speed ball bearings have been investigated empirically using 45mm bore split inner ring ball bearings employed in small industrial gas turbine engines with oil-jet lubrication method. For the close structural simulation, experiments carried out with bearing mounting supports of real engines, such as bearing housings and oil nozzle assemblies with squeeze film dampers. Thus the results of tests can be directly applied to the design and the development of gas turbine engines. Testing was done by varying operating speeds, axial load on bearings, and lubricant flow rates. During testing, the temperature of bearing at outer-ring face, the power consumption of the driving motor, and the rotating resistance of the bearing were measured. From this study, the representative factors for lubrication characteristics at high speed was found, and the most important one was not operating speed but axial load up to 1.95 million dmN speed and 2969 N axial load. Furthermore, the detailed variation of the rotational resistance of the bearing could be visualized by measuring the change of the radial load under the bearing supports. The rotational resistance consists of the frictional resistance and the bearing-cavity oil resistance.

• Journal of Power System Engineering
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• v.15 no.6
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• pp.73-80
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• 2011

The experimental investigation focuses on an influence of artificial aging time in longitudinal butt welded Al 6013-T4 aluminum alloy on the fatigue crack growth resistance. The preferred welding processes for this alloy are frequently tungsten inert gas welding (TIG) process due to its comparatively easier applicability and better weldability than other gas metal arc welding. Fatigue crack growth tests were carried out on compact tension specimens (CT) in longitudinal butt TIG welded after T82 heat treatment was varied in three artificial aging times of 6 hours, 18 hours and 24 hours. Of the three artificial aging times, 24 hours of artificial aging time are offering better resistance against the growing fatigue cracks. The superior fatigue crack growth resistance preferred spatial variation of materials within each specimen in the Paris equation based on reliability theory and fatigue crack growth rate by crack length are found to be the reasons for superior fatigue resistance of 24 hours of artificial aging time was compared to other joints. The highest of crack propagation resistance occurs in artificial aging times of 24 hours due to the increase in grain size (fine grained microstructures).

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.3
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• pp.173-178
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• 2009

We have investigated the electrical properties of oxide metal thin film device. The device has been fabricated top-top electrode structure and its transport properties are measured in order to study the resistance change. Electrical properties with linear voltage sweep on a electrodes are used to show the variation of resistance of oxide metal thin film device. Fabricated oxide metal thin film device with MIM structure is changed from a low conductive Off-state to a high conductive On-state by the external linear voltage sweep. The $Si/SiO_2/MgO$ device is switched from a high resistance state to a low resistance state by forming. Consequently, we believe oxide metal is a promising material for a next-generation nonvolatile memory and other electrical applications.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.69-72
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• 2001

In this paper, we study about a acupuncture point and a non-acupuncture point resistance characteristics for acupuncture research. For this study, we devised resistance variation measurement system. This system is consist of 4-channel skin resistance measuring parts, filters, 12bit A/D convertor, 8051 micro-controller, and personal computer The developed system insert a low current to skin and obtains voltages from standard resistor that is convected to measurement circuit in series. The obtained voltage is converted to 12bit digital signal. Therefore the converted signal is changed to skin resistance by calculation in the personal computer. As the results of experiment, the resistance of acupuncture point and non-acupuncture point are different from each other. The acupuncture point has very fast current flows than the other non- acupuncture point.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.3 no.4
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• pp.256-262
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• 1991

The corrosion effects on thermal contact resistance were experimentally studied for a given contact interface of a couple of metals. 2 cylindrically shaped test pieces, the one was carbon steel whose surface was machined by lathe and the other was stainless steel, ground, were come into contact under pressure, and then submerged to $HNO_3$ gas environment. While the corrosion process was going on, the thermal contact resistance was measured with time. The experiment was performed for 2 cases; 1) Highly compress the test pieces and then bring them to $HNO_3$ gas environment. 2) Anteriorly corrode the interface under low contact pressure and then increase the contact pressure. The results were as follows; In 1st. case of experiment, the thermal contact resistance seemed to be very stable, and showed low values with a tendancy of small decrease with time. But in 2nd. case the resistance was unstable and jumped to a value of 200-250% more then that expected for uncontaminated interface. More over it demonstrated some increase with time.

• 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.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.2
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• pp.162-168
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• 2007

Compatible and incompatible interactions of near-isogenic lines containing one of Xa1, Xa3, and Xa7 resistance genes with Japanese bacterial blight isolates (T7174, T7147, and T7133) were examined in order to determine the variation of bacterial blight resistance and the stability of resistance gene. IRBB 101 line having a Xal gene was compatible (host susceptible) with T7147 and T7133 isolates but incompatible (host resistant) with T7174 isolate at all the tested rice growth stages. IRBB 103 line having a Xa3 gene was susceptible or moderately resistant to the three isolates at seedling and maximum tillering stage but resistant at heading stage. IRBB 101 line having a Xa7 gene was semi-compatible with the three isolates at seedling stage but incompatible at the other growth stages. Overall there were clear differences between compatible and incompatible interactions of rice with Xanthomonas oryzae pv. oryzae races. In the mixed inoculations of compatible and incompatible isolates, the lesion length from near-isogenic lines decreased as the ratios of incompatible races increased. When the distinction between compatible and incompatible isolates was unclear, there was almost no variation of lesion length regardless of mixed ratios. The pathogenicity of the mixed races in the incompatible Interactions increased rather than the individual inoculation whereas the lesion length of compatible interactions was similar to that of the individual inoculation. These data indicate the incompatible races inhibit the virulence of a compatible race but compatible races increase the disease occurrence due to incompatible races. Furthermore, IRBB 107 line that showed resistance to all the isolates at all the tested growth stages was considered as a good parent f3r breeding of resistant variety.