• Composites Research
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• v.23 no.5
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• pp.1-7
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• 2010

To increase the adhesive strength of acrylonitrile butadiene rubber(NBR) and steel plate, the atmospheric pressure flame plasma(APFP) treatment device is applied. The effect of various conditions(processing velocity and distance) is experimentally investigated to ascertain the optimum conditions to yield the best adhesive properties. It is found that the optimum distance between burner port and steel plate is 40mm and the optimum processing velocity is 50m/min at given condition. When the surface is coated twice with the bonding agent, the adhesion strength of APFP treated steel plate is increased to about 20.5%. It suggests that the surface modification of steel by flame plasma treatment at atmospheric pressure is a proper and applicable method to improve the adhesion strength between steel and rubber.

• Journal of the Korean Society for Advanced Composite Structures
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• v.2 no.3
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• pp.30-35
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• 2011

This study investigates the optimum section properties of newly developed steel-concrete composite beam. For that purpose we developed computer program calculating section properties. The suggested new beam section highly contribute to save inter-story height and reduce construction duration and cost compared with conventional steel works such as H-beam and column + RC slab system. But the section shape have different section modulus with upper and lower fiber because of the unsymmetric cross section. Therefore the parametric study on thickness-ratio of top and bottom flange plate is needed. In this paper the change of neutral axis and section modulus for thickness-ratio of up and down flage plate is analysed and discussed.

• Journal of the Korean institute of surface engineering
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• v.40 no.6
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• pp.262-270
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• 2007

Recently, there has been a new appreciation of aluminum alloys as materials that are capable of reducing the environment load. This is because aluminum alloys are lightweight, easy to recycle, permit miniaturization, and have environmental friendly properties. In this study, we investigated the mechanical and electrochemical properties of 5083F aluminum alloys using slow strain rate test(SSRT) and potentiostatic tests under various potential conditions. In the potentiostatic tests, the current density in the potential range from -0.7 to -1.4V after 1,200 s was low. After considering the results of the potentiostatic tests, maximum tensile strength, yield strength, elongation, time-to-fracture, observation of fractured specimen and fractography analysis, the optimum protection potential range was between -1.3 and -0.7V(Ag/AgCl).

• KIEAE Journal
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• v.2 no.3
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• pp.63-70
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• 2002

This study aims to provide the fundamental date of HUANGTO GUDUL for applying to current house heating system. It has been used as a traditional heating system in Korea for a long time and disappeared in the course of industrialization in Korea last a few decades and these days is tend to be widely adopted as house heating system. Even though it is known that the traditional heating system of HUANGTO GUDUL is good for ecological environment house and a kind of the natural friendly heating system for optimum residential heating environment, there are few systematic researches and analysed data of it. In order to analyse the characteristics of HUANGTO GUDUL, the existing materials of it's historical change was studied. And the architectural prospects of the use of GUDUL on the point of view of environmental ecology. The data of relationship between the mechanic properties and the workability of GUDUL materials and the environmental index such as the heating environment, relative humidity, and deodorization ratio and so on. And the heating effectiveness of GUDUL was compared with existing modem materials by experimental analysis. The results stated above can be grafted architecture and will be offered the optimum heating environment.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.2
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• pp.103-116
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• 1993

Recently, engineering ceramics called as the 3 material have been concerned significantly with some excellent mechanical properties and many functions as new materials for high precision mechanical components and engineering parts for at large. Then, for designing engineering parts using engineering ceramics, bending strength value data with high reliability is more essential than any other mechanical properties. But, because of brittleness and structural characteristic, it is very hard to grind with conventional tools, and the generation of cracks and various defects of engineering ceramics parts during grinding machining process are serious problems. Thus, in present study, surface grinding experiments with various machining conditions using resin bond diamond wheels are carried out to obtain the most excellent guality of testpiece surface and optimum step of grinding process for the high efficient stock removal rate to save running time. As the results from grinding experiments and 3-points bending strength test of ground Al2O3 ceramics parts on Korean Standard, manufactured in our country and Japan, basic technology and know-how to develop the optimum grinding machining conditions and also high bending strength values with high reliability are obtained.

• Magazine of the Korean Society of Agricultural Engineers
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• v.15 no.1
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• pp.2904-2912
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• 1973

The density of soil is one of the most important of its engineering properties, and many soil-engineering operations directed toward improving the density characteristics of matecal. This report is a study on relationship between density, permiabilty and other physical properties of compacted soil in various desity grades. The results of the study can be summariged as follow: 1. The optimum moisture content of soil increses with increasing of fine particles and a relationship between both parameter is $w_0=0.1765.n$ Where, n is passing percentage from #200 sieve. 2. The porosity of soil increases with increasing of optimum water content as $e=aw_0+b$ without having relation to compaction ratio. 3. The increment of permeability of soil is high when the compaction ratio is increased and the phenomenon is conspicuous in case of course soil and non-plastic soil. 4. The permeability of soil decreases with increasing of optrimum water content and the phenomenon is conspicuous when compaction ratio decreases. And the permeability is almost constant when optimum water content is more than 25 percent, even though compaction ratio changes. 5. The permeablity of soil increanses when the amount of fine particles is very few, the permeability is almost constant as being impervious condition without having relation to compaction ratio when there in more than 90 percent of fine particles(less than #200 sieve).

• Journal of the Korean Vacuum Society
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• v.8 no.3A
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• pp.194-200
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• 1999

In this paper studied was the piezoelectric properties of the $\beta$-PVDF organic thin films prepared by physical vapour deposition method. The molecular orientation of organic thin films was controlled by the application of an electric field and variation of substrate temperature during the evaporation process. Optimum conditions of manufacturing $\beta$-PVDF organic thin film by physical vapor deposition method is to keep at the substrate temperature of $80^{\circ}C$, at the applied electric field of 142.8 kV/cm. The voltage output coefficient increased from 1.39 to 7.04V increasing the force moment.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.225-225
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• 2010

In this study, the optimum structure of a magnetic thin film inductor was designed for application of DC-DC converters. The $Ni_{81}Fe_{19}$ (at%) alloy was selected as a high-frequency($\geq$ MHz) magnetic thin film core material and deposited on various substrates (bare Si, $SiO_2$ coated Si) using a high vacuum RF magnetron sputtering system. As-deposited NiFe thin films show similar magnetic properties compared to bulk NiFe alloys, indicating that they have a good film quality. The optimum design of solenoid-type magnetic thin film inductors was performed utilizing a Maxwell computer simulator (Ansoft HFSS V7.0 for PC) and parameters obtained from the magnetic properties of magnetic core materials selected. The high-frequency characteristics of the inductance(L) and quality factor(Q) obtained for the designed inductors through simulation agreed well with those obtained by theoretical calculations, confirming that the simulated result is realistic. The optimum structure of high-performance ($Q{\geq}60$, $L\;=\;1{\mu}H$, efficiency${\geq}90%$), high-frequency (${\geq}5MHz$), and solenoid-type magnetic thin film inductors was designed successfully.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.127-130
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• 1999

Physical properties and microstructure of slag blended cement were investigated to evaluate the influence of sulphates and chlorides. The compressive strength developed as high chloride content dust and gypsum added and accordingly the microstructure modification was showed. The deviation of pore size distribution and hydrates was also observed. From these results we discussed optimum condition of gypsum and high chloride content dust leading to physical properties in this study.

• Journal of the Korean Ceramic Society
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• v.12 no.2
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• pp.3-9
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• 1975

The continuous grading method of pyrophyllite particles was adopted to prepare the refractories for ladle. The optimum conditions of fabrication adjusting the binders, the amount of water, the forming pressure and the firing temperature were investigated. The various properties, such as strength, density, porosity, thermal shock, corrosion resistance to slag were measured and compared with properties of ladle bricks presently used at local steel plants. The specimen studied in the present investigation showed a rather superior properties to theconventional product available locally.