• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.85-91
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• 2015

Current world aircraft industry studies on the precision of the product are in active progress. Particularly in terms of improving the quality of processed products in terms of the surface roughness of the dimensional accuracy, fatigue strength, and corrosion resistance, which affect a lot of research on surface roughness, has been investigated. In this study of aluminum alloy, 7075 aircraft aluminum is used in a cutting CNC lathe machine for the cutting speed and feed rate according to the cutting experiments that were conducted. Additionally, the machine tool of the cooling method soluble cutting oil, insoluble cutting oil by cooling, and cooling the workpiece by cutting surface roughness will be investigated. Through the method and soluble cutting oil coolant cooled by the cutting speed increases, the value of surface roughness showed a regular result. Tool nose radius of 0.8 mm than 0.4 mm picture of when approximately 50 of the surface roughness values were less.

• Nuclear Engineering and Technology
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• v.44 no.8
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• pp.945-952
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• 2012

The sorption of selenium ions onto iron and iron compounds as a disposal container material and its corrosion products, and onto bentonite as a buffer material, was studied to understand the behaviors of selenium in a waste repository. Selenite was sorbed onto commercial magnetite very well in solutions at around pH 9, but silicate hindered their sorption onto both magnetite and ferrite. Unlike commercial magnetite and ferrite, flesh synthesized magnetite, green rust and iron greatly decreased selenium concentration even in a silicate solution. These results might be due to the formation of precipitates, or the sorption of selenide or selenite onto an iron surface at below Eh= -0.2 V. Red-colored Se(cr) was observed on the surface of a reaction bottle containing iron powder added into a selenite solution. Silicate influences on the sorption onto magnetite and iron for selenide are the same as those for selenite. Even though bentonite adsorbed a slight amount of selenite, the sorption cannot be ignored in the waste repository since a very large quantity of bentonite is used.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.5
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• pp.589-600
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• 2014

Tuberculation and slime accumulated in water mains play an important role in modifying water quality of drinking water. Therefore, in this study, it was investigated that what materials were accumulated, and what components were included in the tuberculation and slime of water mains. The Various tuberculation and slime sample were collected from the 12 water mains to analyze their physical and chemical properties and crystal structure. As a analysis method, VSS(Volatile suspended solid), SEM(scanning electron microscope), EDS(Energy Dispersive X-ray spectroscope), ICP(Inductively Coupled Plasma Mass Spectrometer) and XRD(X-Ray Diffractomete) were used. The results of analysis on the samples, the representative materials were verified such as iron corrosion products, the fine sand particles generated during backwash, fine particles of activated carbon, aluminum used in coagulation process, and manganese included in raw water.

• Journal of Radiation Protection and Research
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• v.14 no.2
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• pp.37-44
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• 1989

An improved water chemistry technique was studied to reduce radioactivity build-up in reactor coolant system. The technique is convering the current coordinated lithium-boron chemistry regime to the elevated lithium chemistry regime in order to maintain high pH. Correlations between reactor coolant pH and radioactivity build-up were analized by using pH data from domestic PWRs. Consequently, it was founded that high pH chemistry was moer effective for radioactivity build-up reduction than current chemistry regime. This fact had revealed that much portion of reactor coolant corrosion products were nickel ferrite rather than magnetite, and that pH value ranging 7.0-7.4 was appropriate for high-pH chemistry operation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.4
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• pp.121-127
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• 2008

Automatic grease lubricator is an equipment that provides adequate amount of fresh grease constantly to the shaft and bearings of machines. It minimizes the friction heat and reduces the friction loss of machines to the least. This paper is developing an automatic grease lubricator using a mode of the gas generation type from galvanic electricity. The ultimate goal of this equipment is to lubricate an adequate amount of grease with galvanic corrosion. In an electrolyte, combining anode(Mo) with cathode(Zn) is pressing out hydrogen gas of an galvanic element with galvanic reaction. The characteristics of this method is continuous flowing small hydrogen gas and controling the usage of the amount of the generation of hydrogen gas. The exterior body of grease lubricator was analyzed by Digital Mock-up of CATIA V5 and finite element analysis. The maximum stress is distributed over the outlet part where the grease lubricator suddenly narrowly contracts. The outlet part is analyzed with different constructed angle due to the different loading and setting angles. Using the analyzed design, RP trial products were producted and tested.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.5
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• pp.334-342
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• 2009

Trends in the automotive market require the application of new engine technologies, which allows for the use of different types of fuel. Since ethanol is a renewable source of energy and has lower $CO_2$ emissions than gasoline, ethanol produced from biomass is expected to be used more frequently as an alternative fuel. It is recognized that for spark ignition (SI) engines, ethanol has the advantages of high octane number and high combustion speed. Due to the disadvantages of ethanol, it may cause extra wear and corrosion of electric fuel pumps. On-board hydrogen production out of ethanol is an alternative plan. This paper investigates the influence of ethanol fuel on SI engine performance, thermal efficiency and emissions. The combustion characteristics with hydrogen-enriched gaseous fuel from ethanol are also examined. As a result, thermal efficiency increase compared to gasoline. Also, reductions in $CO_2$, NOx, and THC combustion products for ethanol vs. gasoline are described.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2016.11a
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• pp.271-274
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• 2016

본 논문에서는 오존층 파괴 및 지구 온난화에 악영향을 미치는 할로겐화합물 소화약제를 대체하여 개발된 청정소화약제인 할로겐화합물 청정소화약제(Halocarbon clean agent)의 열분해 생성물(thermal decomposition products)의 영향에 평가하고자 한다. 이를 위해 할로겐화합물 청정소화약제인 HFC-125가 화원 크기의 변화에 따른 열분해 생성물의 미치는 영향을 측정하기 위해 소화시험을 실시하였고 금속(철), 비철금속(구리), 유리 시편의 부식성과 전자부품(SD-Card) 작동여부를 평가 하였다. 금속 및 비철금속 시편의 부식성을 측정하기 위해 디지털 카메라를 통해 이미지를 촬영하고 그래픽 편집 소프트웨어를 이용하여 채도(saturation)를 측정하여 부식성의 정도를 분석하였다. 금속, 비철금소, 유리 시편의 부식성 분석 결과, 화원의 크기가 증가할수록 금속 및 비철금속의 부식성이 증가하였다. 즉, 화원의 크기(fire size)에 따라 열분해 생성물질도 증가하여 금속 및 비철금속의 부식을 증가시키는 것으로 사료된다.

• Journal of the Korean Ceramic Society
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• v.46 no.5
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• pp.534-539
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• 2009

Reaction Bonded Silicon Carbide(RBSC) has been used for engineering ceramics due to low-temperature fabrication and near-net shape products with excellent structural properties such as thermal shock resistance, corrosion resistance and mechanical strength. Recently, attempts have been made to develop hot gas filter with gradient pore structure by RBSC to overcome weakness of commercial clay-bonded SiC filter such as low fracture toughness and low reliability. In this study a fabrication process of porous RBSC with multi-layer pore structure with gradient pore size was developed. The support layer of the RBSC with multi-layer pore structure was fabricated by conventional Si infiltration process. The intermediate and filter layers consisted of phenolic resin and fine SiC powder were prepared by dip-coating of the support RBSC in slurry of SiC and phenol resin. The temperature of $1550^{\circ}C$ to make Si left in RBSC support layer infiltrate into dip-coated layer to produce SiC by reacting with pyro-carbon from phenol resin.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.30-31
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• 2015

Usually, carbonation of concrete causes pH reduction and corrosion of steel, it leads to decrease of durability. However, CaCO₃, as results of reaction with hydrates products and CO₂, can contribute to improvement of compressive strength. Based on this theory, using carbonation depth, the researches about CO₂ absorption of plain concrete and concrete containing CO₂ reactive materials has been performed. But, the researches has limitation about using one material, therefore, for this study, considering various CO₂ reactive materials, experiment has been proceeded. With water to binder ratio 50%, after initial curing for 2days, accelerated carbonation was performed for 28days, and carbonation depth and compressive strength were measured. As results of carbonation depth, specimen containing desulfurized slag, zeolite showed the highest CO₂ absorption, in case of compressive strength, specimens with MgO were indicated as highest compressive strength.

• Journal of the Korean institute of surface engineering
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• v.43 no.2
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• pp.64-72
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• 2010

CuSnZn electroplating was investigated as alternative to Ni plating. Evaluation of electrolyte and plating process was performed to control physical characteristics of the film, and to collect practical data for application. Hull-cell test was conducted for basic comparison of two commercialized products and developed product. Based on hull-cell test results, long term test of three electrolytes was performed. Various analysis on long term tested electrolyte and samples have been done. Reliable and practical data was collected using FE-SEM (FEI, Sirion), EDX (ThermoNoran SIX-200E), ICP Spectrometer (GBC Scientifi c, Integra XL), FIB (FEI, Nova600) for anlysis. Physical analysis and reliability test of the long term tested film were also carried out. Through this investigation plating time, plating speed, electrolyte composition, electrolyte metal consumption, hardness and corrosion resistance has been compared. This set of data is used to predict and control the chemical composition of the film and modify the physical characteristics of the CuSnZn alloy.