• Journal of Korea Foundry Society
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• v.43 no.6
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• pp.325-329
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• 2023

높은 주조 품질을 요구받고 있는 대부분의 다이캐스팅업체들은 양산공정을 통해 사용되고있는 용탕의 청정도를 평가하고 모니터링을 해야만 한다. 여러 가지 평가방법들을 사용할 수 있지만 현장에서는 일부 측정방법만이 다이캐스팅에 적용되고 있으며 목적에 맞게 적절하게 사용하여야 한다. 세 가지 가능한 평가 방법인 K-Mold, 기계적물성 평가 및 PoDFA(다공성 디스크 여과 장치) 를 대상으로 소개하고자 한다. 우선, 각 방법들은 서로 사용 목적 목적에 따라 선택될 수 있으며 K-Mold는 현장에서 빠르고 간단하게 적용할 수 있는 방법으로 일정한 규격화된 시편의 파면을 만들고 파단면 관찰을 통해 일정한 크기 이상의 산화물 갯수를 확인하여 용탕의 품질을 관리하는 편리한 평가방법 중 하나다. 기계적 물성 테스트는 용탕 청결도에 대한 정성적, 정량적 정보를 모두 확인할 수 있으며 샘플링 테스트에 적합한 시험법이라 할 수 있다. 또한, PoDFA는 용탕내에 개재물의 종류별 정밀분석과 양에 대한 상대적 비교 분석으로써 현장의 많은 경험을 통하여 데이터 축적하고 분석하는 방법으로 사용방법에 대한 전문교육이 필요하다.

• Applied Biological Chemistry
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• v.40 no.3
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• pp.184-188
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• 1997

A bacterial strain, producing extracellular inulin fructotransferase which converts inulin into di-D-fructofuranose 1,2':2,3' dianhydride(DFA III), was isolated from soil and presumed as Bacillus sp.. The highest production of the enzyme was obtained by using medium containing Jerusalem artichoke extract as carbon source, peptone as organic nitrogen source, and $NH_4H_2PO_4$, as inorganic source. Under optimum condition, the enzyme activity of the culture broth supernatant reached maximal 2.61 units/ml after cultivation for 45 hrs.

• Journal of Korea Foundry Society
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• v.22 no.3
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• pp.130-136
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• 2002

The growing use of aluminum for castings over the past decade has brought with it the increased scrutiny of component properties. One area that has received much attention is the effect of in inclusions - or impurities particles held in the metal - on casting properties. A new method of electromagnetic separation for removal of inclusions in aluminum alloy melts is proposed. The principle is that as the electromagnetic force induced in metal acts on inclusions due to low electric conductivity, they are moved to the direction opposite to electromagnetic force and can be separated and removed from the melt. Experiments were carried out on A356 melt mixed alumina particles and commercial Al alloys of ADC 10 and 12. In the experiment using A356, it was proved that $Al_2O_3$ particles was separated and removed continuously from matrix melt by electromagnetic force. Based on these results, the continuous separation experiment that used ADC 10, 12 was carried and the cleanliness of melt was assessed by the amount of porosity, hydrogen contents, PoDFA and mechanical properties through tensile test. As the results of analyses, the amount of porosity and hydrogen contents decreased without variation of chemical composition in the specimen that passed the electromagnetic continuous separator. In addition, tensile strength and elongation of this specimen increased by $20{\sim}30%$ because of reduction of inclusions.