• 한국환경과학회지
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• 제11권1호
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• pp.75-83
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• 2002

The removal performance of copper ion was studied using Na-P1 zeolites synthesized from Jeju scoria. The scoria which is found in large amounts in Jeju Island, was sampled at four regions, Jeju-shi Bonggae-dong(A). Pukcheju-gun Hanlim-eup Sangmyong-ri Mangoreum(B), Pukcheju-gun Hanlim-eup Keumag-ri(C) and Namcheju-gun Andeok-myun Dongkwang-ri(D). Synthetic Na-P1 zeolites used in this study were more effective than natural zeolite and scoria for the removal of copper ion. The removal performances of copper ion decreased in the order of Na-P1(D) > Na-P1(C) > Na-P1(B) > Na-P1(A) among Na-P1 synthesized from the scoria according to region. These results showed the same trend with cation exchange capacity(CEC) for each synthetic zeolite, i.e., the synthetic Na-P1 zeolite with a higher CEC showed a higher removal performance. The effective diffusion coefficients of copper ion by synthetic Na-P1 zeolites were one hundred and ten times higher than those by a pure zeolite 4A and the zeolite A synthesized from coal fly ash, respectively.

• 한국재료학회지
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• 제11권9호
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• pp.802-809
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• 2001

Electroplating is an attractive alternative deposition method for copper with the need for a conformal and conductive seed layer In addition, the Cu seed layer should be highly pure so as not to compromise the effective resistivity of the filled copper interconnect structure. This seed layer requires low electrical resistivity, low levels of impurities, smooth interface, good adhesion to the barrier metal and low thickness concurrent with coherence for ensuring void-free fill. The electrical conductivity of the surface plays an important role in formation of initial Cu nuclei, Cu nucleation is much easier on the substrate with higher electrical conductivities. It is also known that the nucleation processes of Cu are very sensitive to surface condition. In this study, copper seed layers deposited by magnetron sputtering onto a tantalum nitride barrier layer were used for electroplating copper in the forward pulsed mode. Prior to electroplating a copper film, the Cu seed layer was cleaned by plasma H$_2$ and $N_2$. In the plasma treatment exposure tome was varied from 1 to 20 min and plasma power from 20 to 140W. Effects of plasma pretreatment to Cu seed/Tantalum nitride (TaN)/borophosphosilicate glass (BPSG) samples on electroplating of copper (Cu) films were investigated.

• 한국재료학회지
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• 제15권9호
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• pp.555-559
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• 2005

An oxygen free copper severely-deformed by eight cycles (an equivalent strain of $\~6.4$) of accumulative roll-bonding (ARB) was annealed at various temperatures ranging from 100 to $300^{\circ}C$. The annealed copper was characterized by transmission electron microscopy (TEM) and tensile & hardness test. TEM observation revealed that the ultrafine grains developed by the ARB still remained up to $150^{\circ}C$, however above $200^{\circ}C$ they were replaced by equiaxed and coarse grains due to an occurrence of the static recrystallization. Tensile strength and hardness of the copper decreased slightly with the annealing temperature up to $150^{\circ}C$, however they dropped largely above $200^{\circ}C$. Annealing characteristics of the copper were compared with those of a commercially pure aluminum processed by ARB and subsequently annealed.

• 전기화학회지
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• 제10권3호
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• pp.175-178
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• 2007

Pure iron, Fe-0.4, and 1.2 wt.%Cu alloys were examined by conducting the electrochemical techniques in the weakly alkaline solution, pH9, controlled by $Ca(OH)_2$, solution added with 0.02M NaCl. The $R_P$ measured from ac impedance, selected 10 kHz and 10mHz, in weakly alkaline solutions containing chloride ions indicated that the addition of copper up to 1.2wt.% into the pure iron significantly improved the pitting resistance of iron. In contrast to alloy, the pure iron showed the rapid pitting occurrences in drying period. During the drying period, the corrosion potential of pure iron was shifted to less noble value, pitting initiation.

• 한국재료학회지
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• 제21권5호
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• pp.263-267
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• 2011

The present study was carried out to evaluate the microstructural and mechanical properties of cross-roll rolled pure copper sheets, and the results were compared with those obtained for conventionally rolled sheets. For this work, pure copper (99.99 mass%) sheets with thickness of 5 mm were prepared as the starting material. The sheets were cold rolled to 90% thickness reduction and subsequently annealed at $400^{\circ}C$ for 30 min. Also, to analyze the grain boundary character distributions (GBCDs) on the materials, the electron back-scattered diffraction (EBSD) technique was introduced. The resulting cold-rolled and annealed sheets had considerably finer grains than the initial sheets with an average size of 100 ${\mu}M$. In particular, the average grain size became smaller by cross-roll rolling (6.5 ${\mu}M$) than by conventional rolling (9.8 ${\mu}M$). These grain refinements directly led to enhanced mechanical properties such as Vickers micro-hardness and tensile strength, and thus the values showed greater increases upon cross-roll rolling process than after conventional rolling. Furthermore, the texture development of <112>//ND in the cross-roll rolling processed material provided greater enhancement of mechanical properties relative to the case of the conventional rolling processed material. In the present study, we systematically discuss the enhancement of mechanical properties in terms of grain refinement and texture distribution developed by the different rolling processes.

• 대한화학회지
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• 제55권4호
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• pp.620-625
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• 2011

구리수은막 전극(CBMFE)으로 전위차 역적정함으로써 이소니아자이드(INH)를 정량하는 간단하고 빠른 방법이다. 순수한 형태와 투약형태에 대해서 1.0-10.0 mg 범위에서 정량 할 수 있도록 적정조건을 설정하였다. 방법의 정밀도와 정확도는 통계적인 방법으로 평가되었으며, 정제와 시럽속에 함유된 INH 정량법은 F-시험과 t-시험을 통하여 영국약전(BP) 방법과 비교하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.55-59
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• 2003

Rotor in small-medium induction motor has been usually manufactured by aluminum diecasting. In order to improve efficiency of induction motors, however, it is desirable that pure aluminum is replaced by high electrical conductivity copper alloy. For this purpose, a rotor is thixoformed with Cu-Ca alloy. Thermomechanical processing(TMP) is carried out to modify the semi-solid microstructure of the alloy and final microstructures and filling defects of thixoformed Cu- rotors are investigated. The characteristics of thixoformed Cu-rotor such as motor efficiency and torque are compared with those of Al rotor.

• 한국표면공학회지
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• 제36권2호
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• pp.194-199
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• 2003

Polarization measurements were peformed to investigate the electrochemical behavior of copper ions and limiting current density in waste rinse water from copper electroplating processes. A newly designed cyclone type electrolyzer was tested to recover the copper powder. Synthetic solutions were prepared using analytical grade $CuSO_4$ to the desired waste water concentration and pH was adjusted with $H_2$$SO_4$. Electrowinning was peformed at room temperature and the solution was cycled with a pump. Results showed that more than 99 percent of Cu was recovered and the size of the recovered Cu powder ranges from 0.1 - $0.5\mu\textrm{m}$. The chemical composition of the Cu powder mainly consists of $Cu_2$O and Cu and can be easily reduced to pure Cu powder.

• 한국분무공학회지
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• 제25권2호
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• pp.68-73
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• 2020

In the present study, experiments on the film boiling of liquid droplets on oxidized copper surface was conducted. The shape of pure water droplets was observed, and the evaporation rate of them was measured during the film boiling evaporation process. The droplet of initial volume 16 ~ 30 µl was applied onto the oxidized copper surface heated up to 300 ~ 500℃, then the shape of the droplet was analyzed during the film boiling evaporation. Experimental results showed that there was good correlation between dimensionless volume and dimensionless time. However, a significant difference in evaporation rate for small and large droplets discussed in previous study was not found.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1470-1474
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• 2004

'Nanofluids' means suspension of common fluids with particles of the order of nanometers in size. The present research is an experimental study of critical heat flux (CHF) behavior in pool boiling of $water-TiO_2$ nanofluids under atmospheric pressure. CHF for pure water and $water-TiO_2$ nanofluids were respectively measured using disk-type copper block heater with 10mm diameter, and CHF of water with surfactant was also measured to consider the effect of surfactant used to disperse nanoparticle. The results show a large increase in CHF for $water-TiO_2$ nanofluids compared to pure water. After CHF occurred, heat flux in pool boiling for $water-TiO_2$ nanofluids was maintained in considerable value, but not for pure water.