• 한국건설관리학회논문집
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• 제17권2호
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• pp.135-145
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• 2016

최근 국내 공동주택 골조공사에 있어서 소음저감형 알루미늄 거푸집의 활용이 증가하고 있다. 그러나 현재까지 개발된 소음저감형 알루미늄 거푸집은 복잡한 작업프로세스로 인해 작업 생산성이 저하되고, 특히 설치 해체 작업 시 알루미늄의 물성으로 인해 발생하는 소음을 여전히 방지하지 못한다는 문제점을 지니고 있다. 따라서 본 연구의 목적은 새로운 소음저감형 알루미늄 거푸집의 최적 개념디자인을 제안하고, 최적 개념디자인을 토대로 제작된 워킹목업(Working Mock-up)의 기술적 타당성을 검토하는 것이다. 이를 위해 본 연구에서는 기존 알루미늄 거푸집의 분석을 통해 새로운 형태의 소음저감형 알루미늄 거푸집 개넘디자인 3개 안을 도출하였으며, 현장 전문가 설문조사를 통해 AHP 분석을 수행하였다. AHP 분석 기법을 활용하여 Trade-off Analysis를 수행한 결과, 안전성(0.52)과 작업편의성(0.54) 부분에서 가장 높은 가중치 값이 도출된 '드롭다운 동바리와 가변빔이 적용된 소음저감형 시스템 알루미늄 거푸집'이 최적 개념디자인으로 선정되었다. 본 연구를 통해 도출된 소음저감형 알루미늄 시스템 거푸집의 최적 개념디자인은 기존 소음저감형 시스템 거푸집의 문제점을 해결하고, 실질적인 소음저감은 물론 작업 편의성 및 노무자의 안전성이 제고된 실제 소음저감형 알루미늄 거푸집의 개발에 활용될 수 있을 것으로 기대된다.

• 소성∙가공
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• 제14권4호
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• pp.319-326
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• 2005

In this study, the nano-deformation behavior of semi-solid Al-Si alloy was investigated using a molecular dynamics simulation as a part of the research on the surface crack behavior in thixoformed automobile parts. The microstructure of the grain-size controlled Al-Si alloy consists of primary and eutectic regions. In eutectic regions the crack initiation begins with initial fracture of the eutectic silicon particles and inside other intermetallic phases. Nano-deformation characteristics in the eutectic and primary phase of the grain-size controlled Al-Si alloy were investigated through the molecular dynamics simulation. The primary phase was assumed to be single crystal aluminum. It was shown that the vacancy occurred at the zone where silicon molecules were.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.299-302
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• 2005

Semisolid A356 slurries were prepared by electromagnetic stirring casting and by inoculation of Al-5Ti-B master alloy. As stirring time and addition of Al-5Ti-B are different, the grain size of the primary phase is different. Through the experiment of rheocast in a Buhler horizontal die casting machine, it was found that the finer the equiaxed primary dendrites, the smoother the die filling and better cast quality. Small equiaxed primary dendrite also results in less liquid segregation on the surface.

• 대한금속재료학회지
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• 제47권6호
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• pp.356-362
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• 2009

In order to vary the primary recrystallization textures, AA 1050 sheets were cold rolled in two different manners. Differences in cold rolling schedule gave rise to the formation of different cold rolling textures also leading to the formation of different primary recrystallization textures. Upon annealing for grain growth, changes in microstructure and texture hardly occurred in the sample depicting Cube recrystallization texture, while grain growth was accompanied with the development {001}<100> Cube texture in the sample displaying a recrystallization texture comprising of weak rolling texture components. The selective growth of Cube oriented grains is attributed to the high mobility of their grain boundaries.

• Bulletin of the Korean Chemical Society
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• 제15권2호
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• pp.132-138
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• 1994

Bis(diethylamino)aluminum hydride was utilized in a systematic study of the approximate rates and stoichiometry of the reaction of excess reagent with 55 selected organic compounds containing representative functional groups under standardized conditions (THF, $0^{\circ}C$, reagent to compound=4 : 1) in order to define the characteristics of the reagent for selective reductions. The reducing action of BEAH was also compared with that of the parent aluminum hydride. The reducing action of the reagent is quite similar to that of aluminum hydride, but the reducing power is much weaker. Aldehydes and ketones were readily reduced in 1-3 h to the corresponding alcohols. However, unexpectedly, a ready involvement of the double bond in cinnamaldehyde was realized to afford hydrocinnamyl alcohol. The introduction of diethylamino group to the parent aluminum hydride appears not to be appreciably influential in stereoselectivity on the reduction of cyclic ketones. Both p-benzoquinone and anthraquinone utilized 2 equiv of hydride readily without evolution of hydrogen, proceeded cleanly to the 1,4-reduction products. Carboxylic acids and acid chlorides underwent reduction to alcohols slowly, whereas cyclic anhydrides utilized only 2 equiv of hydride slowly to the corresponding hydroxylacids. Especially, benzoic acid with a limiting amount of hydride was reduced to benzaldehyde in a yield of 80%. Esters and lactones were also readily reduced to alcohols. Epoxides examined all reacted slowly to give the ring-opened products. Primary and tertiary amides utilized 1 equiv of hydride fast and further hydride utilization was quite slow. The examination for possibility of achieving a partial reduction to aldehydes was also performed. Among them, benzamide and N,N-dimethylbenzamide gave ca, 90% yields of benzaldehyde. Both the nitriles examined were also slowly reduced to the amines. Unexpectedly, both aliphatic and aromatic nitro compounds proved to be relatively reactive to the reagent. On the other hand, azo- and azoxybenzenes were quite inert to BEAH. Cyclohexanone oxime liberated 1 equiv of hydrogen and utilized 1 equiv of hydride for reduction, corresponding to N-hydroxycyclohexylamine. Pyridine ring compounds were also slowly attacked. Disulfides were readily reduced with hydrogen evolution to the thiols, and dimethyl sulfoxide and diphenyl sulfone were also rapidly reduced to the sulfides.

• 한국대기환경학회지
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• 제34권2호
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• pp.331-341
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• 2018

Hazardous air pollutants(HAPs) in the atmosphere are regulated as major air pollutants in Korea by the Air Pollution Control Act. In order to manage and control HAPs, accurate standards, which are traceable to the International System of Units(SI), are required. In this study, primary standard gas mixtures(PSMs) of volatile organic compounds(VOCs) which are specified as HAPs were developed at $1{\mu}mol/mol$ levels. The selected fourteen VOCs include Benzene, Toluene, Ethylbenzene, m-Xylene, Styrene, o-Xylene, Chloroform, 1,1,2-Trichloroethane, Trichloroethylene, Tetrachloroethylene, 1,1-Dichloroethane, Carbon tetrachloride, 1,3-Butadiene, and Dichloromethane. The HAPs PSMs were gravimetrically prepared in aluminum cylinders and their consistency was verified within the relative expanded uncertainty of 0.71% (k=2). Potential adsorption loss onto the internal surface of cylinders was estimated by cylinder-to-cylinder division method. No adsorption loss was observed within the uncerainty of 0.53%. The long-term stability of the HAPs PSMs was evaluated comparing with freshly prepared HAPs PSMs. The HAPs PSMs were stable for one year within the uncertainty of 0.38%. The final uncertainty of the PSMs was determined by combining the preparation uncertainty, verification uncertainty, and stability uncertainty. Finally, traceable and stable HAPs PSMs at $1{\mu}mol/mol$ levels were developed with the uncertainty of less than 0.76% in high-pressure aluminum cylinders.

• 대한조선학회논문집
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• 제48권3호
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• pp.189-199
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• 2011

Austenite stainless steel(ASS), aluminum alloy and nickel steel alloy are the most widely used in many cryogenic applications due to superior mechanical properties at low temperature. The Face-Centered Cubic(FCC) and Hexagonal Close-Packed(HCP) materials are used for the primary and secondary insulation barrier of Liquefied Natural Gas(LNG) carrier tank and various kinds of LNG applications currently. In this study, tensile tests of ASS, aluminum alloy and nickel steel alloy were carried out for the acquisition of quantitative mechanical properties under the cryogenic environment. The range of thermal condition was room temperature to $-163^{\circ}C$ and strain rate range was 0.00016/s to 0.01/s considering the dependencies of temperatures and strain rates. The comprehensive test data were analyzed in terms of the characteristics of mechanical behavior for the development of constitutive equation and its application.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.715-718
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• 2001

This study uses traditional alum coagulation and sedimentation process to treat CMP wastewater from cleaning after polishing. The primary goal is to successfully recycle both solid fines and water for semiconductor manufacturing. Results indicated that CMP wastewater may be successfully treated to recover clean water and fine particles by alum coagulation. The optimum operating conditions for coagulation are as fellowing: alum dosage of 10 ppm, pH at 5, rapid mixing speed at 800 rpm, 5 min rapid mixing time, and long slow mixing time. The treated water with low turbidity and an average residual aluminum ion concentration of 0.23 ppm may be considered for reuse. The settled sludge after alum coagulation contains mainly SiO$_2$particle with a minor content of aluminum (1.7 wt%) may be considered as raw materials for glass and ceramic industry.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.127-127
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• 2017

Aluminum is the most abundant metallic element in the Earth's crust and considered as the most limiting factor for plant productivity in acidic soils. The inhibition of root growth is recognized as the primary effect of Al toxicity. Seeds of wheat cv. Keumkang (Korean cultivar) were germinated on petridish for 5 days and then transferred hydroponic apparatus which was treated with $0{\mu}M$ $AlCl_3$ (control), $100{\mu}M$ $AlCl_3$ and $150{\mu}M$ $AlCl_3$ for 5 days. The length of roots, shoots and fresh weight of wheat seedlings were decreased under aluminum stress. The concentrations of $K^+$, $Mg^{2+}$ and $Ac^{2+}$ were decreased whereas $Al^{3+}$ and $P_2O_5{^-}$ concentration was increased under aluminum stress. Using confocal microscopy, the fluorescence intensity of aluminum was increased with morin staining. In this study, a proteome analysis was performed to identify proteins, which is responsible to aluminum stress in wheat roots. In 10-day-old seedlings, proteins were extracted from roots and separated by 2-DE, stained by CBB. Using image analysis, a total of 47 differentially expressed protein spots were selected, whereas 19 protein spots were significantly up-regulated such as s-adenosylmethionine, oxalate oxidase, malate dehydrogenase, cysteine synthase, ascorbate peroxidase and 28 protein spots were significantly down-regulated such as heat shock protein 70, o-methytransferase 4, enolase, amylogenin by aluminum stress following protein spots analyzed by LTQ-FTICR mass spectrometry. The results provide the global picture of Al toxicity-induced alterations of protein profiles in wheat roots, and identify the Al toxicity-responsive proteins related to various biological processes that may provide some novel clues about plant Al tolerance.

• 한국포장학회지
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• 제24권1호
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• pp.13-16
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• 2018

Powdered infant formula is susceptible to oxidation in the presence of oxygen. Even though the product is usually packaged in nitrogen atmosphere, the oxygen ingress through the package layer may occur in case of flexible pouches and affects the oxidation of the product. $O_2$ barrier of the package is thus important variable to protect the product from oxidative deterioration. $O_2$ barrier property was investigated for aluminum-laminated small pillow packs of $3.5{\times}17.5cm$. Storage temperature and combination of primary and secondary packages were evaluated as variables affecting the barrier for conditions of empty pouch flushed with nitrogen. Apparent oxygen transmission rate of the primary package exposed to air was $2.32{\times}10^{-3}mL\;(STP)\;atm^{-1}\;d^{-1}$ at $30^{\circ}C$ and its temperature dependence could be explained by activation energy of $28.5kJ\;mol^{-1}$ in Arrhenius relationship. The additional secondary package of nylon/PE film containing 20 primary packages was ineffective in modulating package $O_2$ transmission and was only marginally helpful when combined with oxygen scavenger. The same was true in suppressing the product oxidation when the primary package was filled with 14 g of the formula.