• 한국재료학회지
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• 제21권6호
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• pp.314-319
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• 2011

Melt foaming method is one of cost-effective methods to make metal foam and it has been successfully applied to fabricate Mg foams. In this research, AZ31 Mg alloy ingot was used as a metal matrix, using AlCa granular as thickening agent and $CaCO_3$ powder as foaming agent, AZ31 Mg alloy foams were fabricated by melt-foaming method at different foaming temperatures. The porosity was above 41.2%~73.3%, pore size was between 0.38~1.52 mm, and homogenous pore structures were obtained. Microstructure and mechanical properties of the AZ31 Mg alloy foams were investigated by optical microscopy, SEM and UTM. The results showed that pore structure and pore distribution were much better than those fabricated at lower temperatures. The compression behavior of the AZ31 Mg alloy foam behaved as typical porous materials. As the foaming temperature increased from $660^{\circ}C$ to $750^{\circ}C$, the compressed strength also increased. The AZ31 Mg alloy foam with a foaming temperature of $720^{\circ}C$ had the best energy absorption. The energy absorption value of Mg foam was 15.52 $MJ/m^3$ at a densification strain of 52%. Furthermore, the high energy absorption efficiencies of the AZ31 Mg alloy foam kept at about 0.85 in the plastic plateau region, which indicates that composite foam possess a high energy absorption characteristic, and the Vickers hardness of AZ31 Mg alloy foam decreased as the foaming temperature increased.

• 한국수산과학회지
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• 제37권6호
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• pp.498-504
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• 2004

Removal of waste generated by Paralichthys olivaceus in the seawater aquarium using a foam separator was investigated. Protein concentration without a foam separator continuously increased until 3 days after stocking and reached at 25 mg/L after 5 days stocking, but protein concentration became lower than the initial protein concentration (2.5 mg/L) with a foam separator. The trends of other fish wastes such as ammonia, total suspended solids (TSS) and chemical oxygen demand (COD) were similar to protein. Dissolved oxygen (DO) in the aquarium decreased below 6.0 mg/L without a foam separator, but with a foam separator the average DO in the aquarium was 7.3 mg/L. Foam separation with the increase of superficial air velocity (SAV) was more effective than that with the fixed SAV. This study showed that wastewater. treatment of seawater aquarium using a foam separator is effective method for a fish waste removal and oxygen supply.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.382-387
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• 2004

Nanoindentation technique has been used to measure the mechanical properties of aluminium alloy foam cell walls. Al-Si-Cu-Mg alloy foams of different compositions and different cell morphologies were produced using powder metallurgical method. Cell morphology of the foam was controlled during production by varying foaming time and temperature. Mechanical properties such as hardness and Young's modulus were calculated using two different methods: a continuous stiffness measurement (CSM) and an unloading stiffness measurement (USM) method. Experimental results showed that hardness and Young's modulus of Al-5%(wt.)Si-4%Cu-4%Mg (544 alloy) precursor and foam walls are higher than those of Al-3%Si-2%Cu-2%Mg (322 alloy) precursor and foam walls. It was noticed that mechanical properties of cell wall are different from those of precursor materials.

• 한국재료학회지
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• 제22권6호
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• pp.309-315
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• 2012

Metal foam has many excellent properties, such as light weight, incombustibility, good thermal insulation, sound absorption, energy absorption, and environmental friendliness. It has two types of macrostructure, a closed-cell foam with sealed pores and an open-cell foam with open pores. The open-cell foam has a complex macrostructure consisting of an interconnected network. It can be exploited as a degradable biomaterial and a heat exchanger material. In this paper, open cell Mg alloy foams have been produced by infiltrating molten Mg alloy into porous pre-forms, where granules facilitate porous material. The granules have suitable strength and excellent thermal stability. They are also inexpensive and easily move out from open-cell foamed Mg-Al alloy materials. When the melt casting process used an inert gas, the molten magnesium igniting is resolved easily. The effects of the preheating temperature of the filler particle mould, negative pressure, and granule size on the fluidity of the open cell Mg alloy foam were investigated. With the increased infiltration pressure, preheat temperature and granule sizes during casting process, the molten AZ31 alloy was high fluidity. The optimum casting temperature, preheating temperature of the filler particle mould, and negative pressure were $750^{\circ}C$, $400-500^{\circ}C$, and 5000-6000 Pa, respectively, At these conditions the AZ31 alloy had good fluidity and castability with the longest infiltration length, fewer defects, and a uniform pore structure.

• 한국염색가공학회지
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• 제31권3호
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• pp.177-186
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• 2019

In this study, we investigated for synthetic hydrotalcite in chloroprene rubber foam. Experiments were carried out to find the optimum content ratio by controlling the contents of MgO and Hydrotalcite. Swelling test in toluene immersion was made to measure the crosslinking density of CR foams, and the cure properties were investigated with flat die rheometer and Mooney viscosity. The difference of hardness, tensile strength and elongation at break were observed after immersing in 7% NaCl or 21% NaCl solutions for a day and four days. In addition, the volume change and water content remaining in CR foam were measured after immersing NaCl solution. As content of MgO increased, the value of the cure torque tended to increase, but it was almost constant above 2phr of MgO. However, the Mooney viscosity decreased with increasing MgO content. The crosslinking density, determined by the swelling ratio, showed that the CR compound without MgO showed a higher degree of swelling. When the content of hydrotalcite/MgO was 3:2, it was the lowest volume change of CR form. Also, As the content of hydrotalcite decreased, the difference of mechanical properties before and after immersion NaCl solution increased.

• 한국미생물·생명공학회지
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• 제17권4호
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• pp.343-348
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• 1989

L. erythrorhizon 세포를 polyurethane foam과 함께 증식시킬 경우 shikonin 유도체가 polyurethane에 효과적으로 흡착됨과 동시에 polyurethane을 사용하지 않은 경우와 비교하여 shikonin 생산량이 현저히 증가하였다. 이 같은 증가는 세포를 polyurethane pore에 고정하여 증식시킴으로써 원활한 세포간 접촉을 유지하고 세포 내에 shikonin 농도를 저하시켜shikonin 생성에 좋은 조건을 제공함에 기인한 것으로 생각되었다. 공정의 생산성을 높이기 위하여 여러가지 배양시스템이 검토되었는데, indole-3-acetic acid(1.75mg/ι)와 kinetin(0.1mg/ι)을 함유하는 Schenk-Hildebrandt 배지 (SHIK 배지) 시스템이 가장 효과적이었다. p-Chlorophenoxyacetic acid (2.0 mg/ι)와 kinetin (0.1 mg/ι)를 함유하는 Schenk-Hildebrandt 배지 (SHND 배지) 시스템에 비교하여 SHIK 배지 시스템에서 Shikonin 생성량은 약 4.5배 증가하였다. Polyurethane을 세포를 고정화하는 지지체로 사용할 경우에는 현재 행하여지고 있는 2단계 배양보다 1단계 배양이 더욱 효과적이며 경제적으로도 매우 유리할 것으로 판단되었다.

• 대한기계학회논문집A
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• 제27권10호
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• pp.1686-1694
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• 2003

The foam-filled tube beams can be used for the front rail and firewall structures to absorb impact energy during frontal or side collision of vehicles. In the case of side collision where bending is involved in the crushing mechanism, the foam filler would be effective in maintaining progressive crushing of the thin-walled structures so that much impact energy could be absorbed. In this study, bending behaviors of the closed-cell-aluminum-alloy-foam-filled stainless steel tube were investigated. The various foam-filled specimens including piecewise fillers were prepared and tested. The aluminum-alloy-foam filling offered the significant increase of bending resistance. Their suppression of the inward fold formation at the compression flange as well as the multiple propagating folds led to the increase of load carrying capacity of specimens. Moreover, the piecewise foams would provide the easier way to fill the thin-walled shell structures without the drawback of strength.

• 한국주조공학회지
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• 제31권3호
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• pp.145-151
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• 2011

Metallic foam has been known as a functional material which can be used for absorption properties of energy and sound. The unique characteristics of Al foam of mechanical, acoustic, thermal properties depend on density, cell size distribution and cell size, and these characteristics expected to apply industry field. Al-Zn-Mg-Cu alloy foams was fabricated by following process; firstly melting the Al alloy, thickening process of addition of Ca granule to increased of viscosity, foaming process of addition of titanium hydride powder to make the pores, holding in the furnace to form of cooling down to the room temperature. Metal foams with various porosity level were manufactured by change the foaming temperature. Compressive strength of the Al alloy foams was 2 times higher at 88% porosity and 1.2 times higher at 92% porosity than pure Al foams. It's sound and vibration absorption coefficient were higher than pure Al foams and with increasing porosity.

• 공업화학
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• 제10권5호
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• pp.731-736
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• 1999

식물성 천연 유지인 콩기름을 peracetic acid로 에폭시화 시킨 후에 황산 촉매 하에서 메탄올과 반응시켜서 OH-value가 186(mg KOH/g)인 폴리올을 합성하였다. 합성한 폴리올에 계면활성제로는 silicon계 B-8409를, 발포제로는 증류수를, 촉매로는 dimethylcyclohexylamine을, 이소시아네이트로는 polymeric MDI를 사용하여 폴리우레탄 포옴을 합성하였다. 형성된 포옴의 밀도, 압축강도, 압축탄성률, cell의 구조 등을 조사하였다. MDI의 당량비를 변화시켜 가며 포옴을 형성시켜 보았으며, MDI index를 105로 고정하고, 발포제, 계면활성제, 촉매의 양을 각각 변화시켜 가며 포옴을 형성시켜 보았다. MDI index가 증가할수록 밀도와 압축 물성이 증가하였다.

• Journal of Animal Science and Technology
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• 제47권6호
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• pp.1033-1040
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• 2005

본 연구는 분리한 ovotransferrin의 식품소재로서의 단백질 특성과 병원성 미생물에 대한 항균능력을 측정하기 위해 실시하였다. 분리한 ovotransferrin의 수분 흡착력을 pH 3, 7, 11의 조건에서 살펴보았을 때 중성조건에서 다소 증가하는 경향을 보였지만 유의적인 차이는 없었다. 기포의 생성과 안정성은 산성조건인 pH 3에서 기포가 가장 적은 양이 발생되었고 시간이 지남에 따라 급속하게 사라지는 경향을 보였으며 중성조건인 pH 7에서는 기포의 감소의 폭이 적어 안정하게 유지됨을 보였다. 온도가 ovotransferrin의 기포의 발생과 안정성에 미치는 영향은 60℃에서 기포의 발생이 가장 높았으나 처리온도가 90℃ 이상이 되면 현저하게 감소하는 것으로 나타났다. Ovotransferrin의 항균 및 항 곰팡이 효과를 측정해 본 결과 농도에 따른 유의적인 저해효과는 없었으나 다만 25mg/ml의 농도로 처리하였을 때 E. coli, S. typhi, P. aerug와 Candida albican에서만 약한 저해 효과를 나타내었다. Albumin과 lysozyme을 ovotransferrin과 혼합사용이 항균 및 항 곰팡이 효과에 영향하는지를 알아본 결과 albumin과 ovotransferrin을 혼합사용 하였을 때 25mg/ml의 농도에서만 S. typhi와 candida albicans의 억제(++) 효과를 보였고 lysozyme과 ovotransferrin의 혼합사용은 12.5mg/ml의 농도에서만 S. typhi에서 약한 저해(+) 효과를 나타냈으며 candida albican에 대해서는 ++정도의 억제효과를 나타내었다. Ovotrnasferrin 자체의 항균 효과는 25mg/ml의 농도에서만 약한 저해효과를 보였으며 ovotransferrin의 항균 및 항 곰팡이 활성을 상승시키기 위한 lysozyme과 albumin의 역할은 그리 크지 않은 것으로 판단되었다.