AlSi10Mg alloys are being actively studied through additive manufacturing for application in the automobile and aerospace industries because of their excellent mechanical properties. To obtain a consistently high quality product through additive manufacturing, studying the flowability and spreadability of the metal powder is necessary. AlSi10Mg powder easily forms an oxide film on the powder surface and has hydrophilic properties, making it vulnerable to moisture. Therefore, in this study, AlSi10Mg powder was hydrophobically modified through silane surface treatment to improve the flowability and spreadability by reducing the effects of moisture. The improved flowability according to the number of silane surface treatments was confirmed using a Carney flowmeter. In addition, to confirm the effects of improved spreadability, the powder prior to surface treatment and that subjected to surface treatment four times were measured and compared using s self-designed recoating tester. The results of this study confirmed the improved flowability and spreadability based on the modified metal powder from hydrophilic to hydrophobic for obtaining a highquality additive manufacturing product.

A study to analyze and solve problems of a stone surface process experiment has presented in this paper. We have taken Taguchi's parameter design approach, specifically orthogonal array, and determined the optimal levels of the selected variables through analysis of the experimental results using S/N ratio.

HF purification performance of an ion exchange membrane(IEM) was evaluated with 0.5% HF spiked with 10ppb of Fe, Ni and Cu nitrates. The result show that after less than five turnovers through an IEM, the metallic impurity concentration drops below 1ppb. The decrease rate can be fitted to a model assuming the experimental tanks to be continuously stirred tank reaction and that the metallic impurity concentration after the IEM is a function of the single-pass purification efficiency of the membrane, the concentration before purification and the metals desorbed form the IEM. The Concentration after purification was investigated up to a cumulative Fe loading of 300ppb in the 23 liter recirculated loop. It increases linearly vs. cumulative loading and can be explained by the Langmuir theory resulting in a purification efficiency at the equilibrium of close to 99.5% in this loading regime.

최근 공공하수처리장의 방류수 수질이 강화됨에 따라 총인 수질 기준을 달성하기 위하여 응집 반응으로 인해 응집제 수요가 늘고 있다. 또한 기후 변화와 이상 기온 현상에 따라 고탁도 유기물 유입이 빈번함에 따라 취수장 및 정수장에서도 응집제 수요가 늘고 있다. 특히 고염기성 무기응집제는 일반 무기응집제와는 달리 응집 범위가 넓고 염기도가 높아 보조응집제(가성소다, 소석회) 등의 추가 사용량이 적으며 탁도의 급격한 변화에서 안정적인 수질 유지가 가능하기 때문에 수요량이 늘고 있는 실정이다. 본 사업은 기업의 제품 생산 공정에서 발생하는 부산물(폐기물)인 30% 염산 및 25% 가성소다 부산물을 활용하여 그림 1과 같이 고염기성 무기응집제를 제조하고자 한다. 본 사업을 통해 생산된 고염기성 무기응집제를 폐수종말처리장 및 정수장에 공급함으로써 염산 부산물 약 4,700톤/년 및 가성소다 부산물 약 3,100톤/년을 재활용할 수 있으며 발생 기업의 폐기물 처리 비용 1.5억원/년 및 고염기성 무기 응집제 구입 비용 1.1억원/년 그리고 신규 사업을 추진함으로써 5.8억원/년의 이윤을 창출할 수 있는 효과를 얻을 수 있을 것으로 예상된다.