• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.259.1-259.1
• /
• 2014

Recently non-thermal plasma has been frequently applied to various research fields. The liquid plasma have received much attention lately because of interests in surgical and nanomaterial synthesis applications. Especially, intensive researches have been carried out for non-thermal plasma in liquid by using various electrode configurations and power supplies. We have developed a bioplasma source which could be used in a liquid, in which outer insulator has been covered onto the outer electrode. Also we have also put an insulator between the inner and outer electrode. Based on the surface discharge mode, the nonthermal bioplasma has been generated inside a liquid by using an alternating current voltage generator with peak voltage of 12 kV under driving frequency of 22 KHz. Here the discharge voltage and current have been measured for electrical characteristics. Especially, We have measured discharge and optical characteristics under various liquids of deionized (DI) water, tap water, and saline by using monochromator. We have also observed nitric oxide (NO), hydrogen peroxide (H2O2), and hydroxyl (OH) radical species by optical emission spectroscopy during the operation of bioplasma discharge inside various kinds of DI water, tap water, and saline. Here the temperature has been kept to be $40^{\circ}C$ or less when discharge in liquid has been operated in this experiment. Also we have measured plasma temperature by high speed camera image and density by using either H-alpha or H-beta Stark broadening method.

• 수산해양기술연구
• /
• 제37권2호
• /
• pp.147-152
• /
• 2001

본 연구에서는 수도수 중에서 Mg합금유전양극에 의한 연강재 온수보일러의 음극방식특성을 연구한 결과 다음과 같은 결론을 얻었다. 1) 온수보일러 관체의 개로전위에서나 전위가 높은 구간에서 모재의 부식전류밀도가 용접부위의 부식전류밀도보다 더 적게 배류된다. 2) 주조된 표면 그대로의 Mg합금 유전양극의 전류밀도는 주조된 표면을 연마한 상태의 Mg합금 유전양극의 전류밀도보다 더 많이 배류된다. 3) Mg합금 유전양극으로부터 거리가 멀어질수록 연강재 온수보일러의 음극방식전위는 높게 나타나고, 음극방식시간이 경과하면서 방식전위는 높게 나타나다가 6-10일 이후부터 방식전위는 안정되고 있다.

• 암석학회지
• /
• 제22권1호
• /
• pp.63-70
• /
• 2013

우리는 선광팬, 일회용 체, 수돗물을 이용해 효과적이고 간편하게 저어콘을 분리하는 방법을 보고한다. 먼저 $230{\mu}m$ 이하로 분말화 한 시료를 약 $10^{\circ}$ 정도 기울인 선광팬에 넣고 물을 흘려보낸다. 밀도가 낮은 입자들과 더불어 선광팬으로부터 넘쳐흐른 물을 망간격이 ${\sim}70{\mu}m$인 체로 걸러낸다. 물의 공급량이 초당 0.1 리터이고 수도꼭지의 높이가 수면으로부터 20-25 cm일 때 가장 효율적으로 저어콘이 분리되었다. 수돗물을 공급한지 20-30분 정도 지나면 다음 작업인 자력 분리(필요시 중액 분리) 또는 저어콘 수선별을 진행할 수 있을 만큼 중광물들이 팬에 모인다. 이 방법은 중액을 사용하는 고전적 방법에 비해 안전하며, 저어콘 뿐만 아니라 모나자이트와 같은 다른 중광물의 분리에도 사용될 수 있다.

• 한국건설순환자원학회논문집
• /
• 제9권2호
• /
• pp.216-222
• /
• 2021

해수 담수화 플랜트에서 배출되는 농축수의 새로운 활용방안을 모색하기 위한 실험이다. 본 연구에서는 염화이온 고정화 효과가 뛰어난 메타카올린을 주요 결합재로 하고 활성화제로 10%와 20%의 산화칼슘을 치환하였다. 그리고 정수(tap-water; TW)와 농축수(reverse osmosis desalination water; RW)를 혼합수로 사용하였다. 실험결과 RW를 사용한 mixture는 TW 보다 더 높은 압축강도를 보였다. 또한 낮은 물-흡수율과 높은 밀도를 나타내었다. RW를 혼합수로 사용한 mixture에서는 Friedel's salt라는 수화반응물질을 관찰할 수 있었다. 강재의 부식문제를 고려한다면 RW는 무철근 콘크리트, 벽돌, 경계석 등의 제품에 적용할 수 있을 것으로 판단된다. 본 연구를 통해 RW의 해양 방출이외에 새로운 활용방안을 제시한 것에 의미 있다고 생각된다.

• 소성∙가공
• /
• 제6권2호
• /
• pp.145-151
• /
• 1997

In order to obtain high quality products in powder metallurgy, it is important to control and understand the densification behavior of metal powders. The effect of the characters of powders on the compaction behavior was studied in this study by using three types of powders produced by the gas atomization, the centrifugal atomization and the twin roll-pulverization. The shape of the powders was a major factor in the apparent or tap density, and the deformation resistance of the matrix of the powders was a major factor in compactibility. Han's yield function (eq.2) for metal powders was simplified from the relationship based on the experimental results of copper powders. In spite of some assumptions, the calculated compaction curves using a new yield functionw was in accordance with the experimental results.

• 한국수산과학회지
• /
• 제12권4호
• /
• pp.261-266
• /
• 1979

부산 근교에서 생산되는 고등 소채류에 대한 세균오염상태를 파악하고 세척, blanching등 처리방법에 따른 세균 제거율과 IMViC system에 의한 대장균군 동정시험 결과를 요약하면 다음과 같다. 1. 엽채류는 과채류에 비하여 분편소대장균의 오염도가 높았다. 2. 수도수로 세척했을 때 생균수 제거율에 있어서는 약 $70\%$, 엽채류에 있어서는 약 $20\%$ 있다. 3. 엽채류를 시판 서첵제로 세척했을 때 생균수 제거율을 약 $80\%$ 수도수로 세척했을때보다 $3\~4$배의 세척 효과가 없었다. 4. 2배의 끊는물에서 1분간 blanching했을 때 생균수 잔재율은 $0.1\%$ 이하있다. 5. 대장균군의 조성은 Eschrichia colr group $18\%$ Citrobacter freundii group $22\%$, Klebsiella aerogenes group $60\%$였으며 이중 Escherichia coli type I 이 $16\%$를 차지하였다. 6. 대장균군 확정시험 배지인 BGLB의 신선성은 약 $80\%$ 였다.

• 한국재료학회지
• /
• 제23권11호
• /
• pp.607-612
• /
• 2013

A powder in sheath rolling method was applied to the fabrication of a carbon nano tube (CNT) reinforced aluminum composite. A 6061 aluminum alloy tube with outer diameter of 31 mm and wall thickness of 2 mm was used as a sheath material. A mixture of pure aluminum powder and CNTs with a volume content of 5% was filled in the tube by tap filling and then processed to an 85% reduction using multi-pass rolling after heating for 0.5 h at $400^{\circ}C$. The specimen was then further processed at $400^{\circ}C$ by multi-pass hot rolling. The specimen was then annealed for 1 h at various temperatures that ranged from 100 to $500^{\circ}C$. The relative density of the 5vol%CNT/Al composite fabricated using powder in sheath rolling increased with increasing of the rolling reduction, becoming about 97% after hot rolling under 96 % total reduction. The relative density of the composite hardly changed regardless of the increasing of the annealing temperature. The average hardness also had only slight dependence on the annealing temperature. However, the tensile strength of the composite containing the 6061 aluminum sheath decreased and the fracture elongation increased with increasing of the annealing temperature. It is concluded that the powder in sheath rolling method is an effective process for fabrication of CNT reinforced Al matrix composites.

• 소성∙가공
• /
• 제24권4호
• /
• pp.287-292
• /
• 2015

The possibility of chemical precipitation for recycled ammonium paratungstate (APT) was studied. WO₃ particles were synthesized by chemical precipitation method using a 1:2 weight ratio of APT:DI-water. At the 500℃ sintering temperature, the X-ray diffraction results showed that APT completely decomposed to WO₃. For the granulated powder WC-Co, vacuum heat treatment at proper temperatures increases tap density and flow-ability. Hardness of the WC-Co thermal spray coating layer was measured in the range HV 831~1266. Spray conditions for the best characteristic values were an oxygen flow rate=1500 scfh, a fuel flow rate = 5.25gph and a gun distance = 320mm.

• 한국분말재료학회지
• /
• 제10권2호
• /
• pp.97-102
• /
• 2003

The powder-in sheath rolling was applied to the fabrication of $Al/Al_2O_3$ composite. A stainless steel tube with outer diameter of 12 mm and wall thickness of 1 mm was used as a sheath. Mixture of aluminum powder and $Al/Al_2O_3$ particles of which volume content was varied from 5 to 20 vol.% was filled in the tube by tap filling and then rolled to 75% reduction at ambient temperature. The re]]ed specimen was sintered at 56$0^{\circ}C$ for 0.5 hr. The $Al/Al_2O_3$ composite fabricated by the sheath rolling and subsequent sintering showed the relative density higher than 0.96. The tensile strength of the composite increased with the volume content of $Al_2O_3$ particles, and it reached a maximum of 90 MPa which is 1.5 times higher than unreinforced material. The elongation decreased with the volume content of $Al_2O_3$ particles. It is concluded that the powder-in sheath rolling is an effective method for fabrication of $Al/Al_2O_3$ composite.

• 한국분말재료학회지
• /
• 제21권1호
• /
• pp.50-54
• /
• 2014

A powder-in-sheath rolling method was applied to a fabrication of a carbon nano tube (CNT) reinforced aluminum composite. A STS304 tube with an outer diameter of 34 mm and a wall thickness of 2 mm was used as a sheath material. A mixture of pure aluminum powders and CNTs with the volume contents of 1, 3, 5 vol was filled in the tube by tap filling and then processed to 73.5% height reduction by a rolling mill. The relative density of the CNT/Al composite fabricated by the powder-in-sheath rolling decreased slightly with increasing of CNTs content, but exhibited high value more than 98. The grain size of the aluminum matrix was largely decreased with addition of CNTs; it decreased from $24{\mu}m$ to $0.9{\mu}m$ by the addition of only 1 volCNT. The average hardness of the composites increased by approximately 3 times with the addition of CNTs, comparing to that of unreinforced pure aluminum. It is concluded that the powder-in-sheath rolling method is an effective process for fabrication of CNT reinforced Al matrix composites.