The current density in copper electroplating is directly related with the productivity; then, to increase the productivity, an increase in current density is required. This study is based on an analysis of changes in surface characteristics and mechanical properties by applying the addition of Alcian Blue (AB, C56H68Cl4CuN16S4). The amount of Alcian Blue in the electrolytes is changed from 0 to 100 ppm. When Alcian Blue is added at 20 ppm, a seed layer is formed homogeneously on the surface at the initial stage of nucleation. However, crystals electroplated in electrolytes with more than 40 ppm of Alcian Blue are observed to have growth in the vertical direction on the surface and the shapes are like pyramids. This tendency of initial nucleation formation causes protrusions when the thickness of copper foil is 12 μm. Thereafter, a lot of extrusions are observed on the group of 100 ppm Alcian Blue. Tensile strength of groups with added Alcian Blue increased by more than 140% compare to no-addition group, but elongation is reduced. These results are due to the decrease of crystal size and changes of prior crystal growth plane from (111) and (200) to (220) due to Alcian Blue.

Electro-coagulation process has been gained an attention recently because it could overcome the membrane fouling problems in MBR(Membrane bio-reactor). Effect of the key operational parameters in electro-coagulation, current density(ρ i) and contact time(t) on membrane fouling reduction was investigated in this study. A kinetic model for ρi and t required to reduce the membrane fouling was suggested under different MLSS(mixed liquor suspended solids) concentration. Total 48 batch type experiments of electro-coagulations under different sets of current densities(2.5, 6, 12 and 24 A/m2), contact times(0, 2, 6 and 12 hr) and MLSS concentration(4500, 6500 and 8500mg/L) were carried out. After each electro-coagulation under different conditions, a series of membrane filtration was performed to get information on how much of membrane fouling was reduced. The membrane fouling decreased as the ρi and t increased but as MLSS decreased. Total fouling resistances, Rt (=Rc+Rf) were calculated and compared to those of the controls (Ro), which were obtained from the experiments without electro-coagulation. A kinetic approach for the fouling reduction rate (Rt/Ro) was carried out and three equations under different MLSS concentration were suggested: i) pi0.39t = 3.5 (MLSS=4500 mg/L), ii) pi0.46t = 7.0 (MLSS=6500 mg/L), iii) pi0.74t = 10.5 (MLSS=8500 mg/L). These equations state that the product of ρi and t needed to reduce the fouling in certain amounts (in this study, 10% of fouling reduction) is always constant.

In commercial solar cells, the pattern of the front electrode is critical to effectively assemble the photo generated current. The power loss in solar cells caused by the front electrode was categorized as four types. First, losses due to the metallic resistance of the electrode. Second, losses due to the contact resistance of the electrode and emitter. Third, losses due to the emitter resistance when current flows through the emitter. Fourth, losses due to the shading effect of the front metal electrode, which has a high reflectance. In this paper, optimizing the number of finger on a 4 ´ 4 solar cell is demonstrated with known theory. We compared the short circuit current density and fill factor to evaluate the power loss from the front metal contact calculation result. By experiment, the short circuit current density(Jsc), taken in each pattern as 37.61, 37.53, and 37.38 mA/ cm2 decreased as the number of fingers increased. The fill factor(FF), measured in each pattern as 0.7745, 0.7782 and 0.7843 increased as number of fingers increased. The results suggested that the efficiency(Eff) was measured in each pattern as 17.51, 17.81, and 17.84 %. Throughout this study, the short-circuit current densities(Jsc) and fill factor(FF) varied according to the number of fingers in the front metal pattern. The effects on the efficiency of the two factors were also investigated.

Recently EC-MBR (Elctrocoagulation - Membrane Bio Reactor) has been suggested as one of alternative processes to overcome membrane fouling problems. Most important operational parameters in the EC-MBR are known to current density and contact time. Their effect on membrane filtration performances has been reported well, however, quantitative interrelationship between both parameters not been investigated yet. The purpose of this study is to give a kinetic model suggesting the current density and the contact time required to reduce the membrane fouling. The 4 different set of current densities (2.5, 6, 12 and 24 A/m2) and contact times (0, 2, 6 and 12 hr) were selected as operational parameters. After each electro-coagulation under the 16 different conditions, a series of membrane filtration was carried out. The membrane fouling decreased as the current density and contact time increased, Total fouling resistances under different conditions, Rt(=Rc+Rf) were calculated and compared to those of the controls (R0), which were calculated from the data of experiments without electro-coagulation. A kinetic approach for the fouling reduction rate (Rt / R0) was carried out and the equation ρi0.46t=7.0 was obtained, which means that the product of current density and the contact time needed to reduce the fouling in certain amounts (in this study, 10% of fouling reduction) is always constant.

The crystallization effects of boron (B) powder on the phase, full width at half maximum (FWHM) values, and critical properties were investigated for in-situ reacted MgB2 bulk superconductors. The semi-crystalline B powder was heat-treated at different temperatures of 1000, 1300 and 1500˚C for 5 hours in an Ar atmosphere. Then, using as-received and heat-treated B powders, the MgB2 samples were prepared at 600˚C for 40 hours in an Ar atmosphere. As the heat-treatment temperature of the B powder increased, both the particle size of the B powder and crystalline phase increased. In the case of MgB2 samples using B powders heat-treated at above 1300˚C, unreacted magnesium (Mg) and B remained due to the improved crystallinity of the B powder. As the heat-treatment temperature of B powder increased, the critical current density of MgB2 decreased continuously due to the reduction of grain boundary density and superconducting volume caused by unreacted Mg and B.

In an effort to overcome the problems which arise when fabricating high-aspect-ratio TSV(through silicon via), we performed experiments involving the void-free Cu filling of a TSV(10~20 μm in diameter with an aspect ratio of 5~7) by controlling the plating DC current density and the additive SPS concentration. Initially, the copper deposit growth mode in and around the trench and the TSV was estimated by the change in the plating DC current density. According to the variation of the plating current density, the deposition rate during Cu electroplating differed at the top and the bottom of the trench. Specifically, at a current density 2.5 mA/cm2, the deposition rate in the corner of the trench was lower than that at the top and on the bottom sides. From this result, we confirmed that a plating current density 2.5 mA/cm2 is very useful for void-free Cu filling of a TSV. In order to reduce the plating time, we attempted TSV Cu filling by controlling the accelerator SPS concentration at a plating current density of 2.5 mA/cm2. A TSV with a diameter 10 μm and an aspect ratio of 7 was filled completely with Cu plating material in 90 min at a current density 2.5 mA/cm2 with an addition of SPS at 50 mg/L. Finally, we found that TSV can be filled rapidly with plated Cu without voids by controlling the SPS concentration at the optimized plating current density.

This study examined the effect of current density on the surface morphology and physical properties of copper plated on a polyimide (PI) film. The morphology, crystal structure, and electric characteristics of the electrodeposited copper foil were examined by scanning electron microscopy, X-ray diffraction, and a four-point probe, respectively. The surface roughness, crystal growth orientation and resistivity was controlled using current density. Large particles were observed on the surface of the copper layer electroplated onto a current density of 25 mA/cm2. However, a uniform surface and lower resistivity were obtained with a current density of 10 mA/cm2. One of the important properties of FCCL is the flexibility of the copper foil. High flexibility of FCCL was obtained at a low current density rather than a high current density. Moreover, a reasonable current density is 20 mA/cm2 considering the productivity and mechanical properties of copper foil.

In this paper, we proposed the optimal process conditions on the electro-gilding process. The responses are plating thickness and Sn proportion. The factors are temperature, current density, and addition. We minimized the total number of experiments based

이온교환막의 전압-전류곡선의 plateau length를 결정하는 변수를 다양한 NaCl 농도와 유속 하에서 연구하였다. 또한, 한계전류밀도 이상의 전류에서 전기투석공정 운전의 타당성을 검토하기 위해 다양한 전류밀도의 전원을 공급하면서 0.1 M NaCl 용액의 탈염실험을 실시하여 이온의 제거효율, 전류효율, 에너지소비량, 물 분해 현상을 측정하였다. NaCl 용액의 농도와 유속이 감소하면서 확산경계층의 두께도 함께 감소하였으며, 본 확산경계층의 두께는 plateau length와도 밀접한 관련이 있는 것으로 나타났다. 탈염실험에서 측정된 이온 제거 효율 및 전류효율은 한계전류밀도 이상에서도 한계전류밀도 이하에서의 탈염실험과 크게 차이 나지 않은 것으로 보아 한계전류밀도 이상에서도 대부분의 전류는 이온교환막 표면의 물분해에 의한 것이 아니라 막을 통한 이온의 이동에 의한 것으로 사료된다. 한계전류밀도 이상에서의 탈염운전에 대한 에너지소비량은 plateau length의 영향으로 한계전류밀도 이하에서의 탈염운전 보다 다소 높지만, 한계전류밀도 이상에서는 전류밀도의 증가에도 에너지소비량이 증가하지 않았다. 이러한 결과들은 물분해 현상이 심각하게 일어나지 않는 한 한계전류밀도 이상에서도 매우 경제적으로 전기투석 공정을 운전찬 수 있다는 것을 제시해 주는 것이다.

균일하고 치밀한 미세구조를 갖는 Pd박막이 PdCl2를 사용하는 전기도금방법으로 제조되었다. 본 연구에서는 도금온도와 전류밀도가 주요 공정변수로서 고려되었고 이에 따른 음극효율 및 제조된 Pd도금막의 결정성, 형상 및 경도 등의 특성이 측정되었고, 이들간의 상호관계성이 검토되었다. 연구결과에 따르면, PdCl2를 사용하는 본 Pd전기도금 시스템에서는 50˚C와 5mA/cm2의 조건이 도금막의 형상으로 볼 때, 최적의 도금조건이라고 간주된다. 최적 조건에서 제조된 Pd도금막의 경도는 약 600kg/mm2이었다. 변수 및 특성간의 관계성 검토 결과, Pd막의 경도는 미세구조에 의해 큰 영향을 받지만, 결정의 배향성과의 연관성은 작은 것으로 해석된다.

10-50wt% 범위의 W을 함유하는 Ni-W 합금을 전기도금에 의해 제조하였다. 합금 중의 W 량은 전류밀도가 증가함에 따라 증가하였다. 전류밀도가 50mA/cm2이하인 경우 Ni-W합금은 미세한 결정립을 갖는 Ni의 고용체이었으며, 전류밀도가 50mA/cm2이상인 경우 비정질상으로 변화하였다. 이들의 결정질→비정질 천이는 W량이 40-46wt%인 구간에서 일어났으며 반각폭이 3배이상으로 증가하였다. 결정질 합금의 격자상수는 평형상태도 상의 W의 고용한계(약 30wt%)를 초과하는 40wt%까지 연속적으로 증가하는 것으로 나타나 Ni이 W을 과고용하고 있는 상태인 것으로 밝혀졌다. 비정질 Ni-W 합금은 400˚C이상의 온도에서 열처리하면 강한 [111]방향성을 가지며 재결정하였으며, 800˚C이상의 온도에서는 과고용된 W이 석출하였다. 합금조성 및 결정구조의 전류밀도 의존성을 이용하여 Ni-30%W과 Ni-50%W 합금층이 반복되는 결정질/비정질의 다층도금을 제조하였다.

은 튜브에 장입되기 전의 초기 분말의 입자 크기가 Ag/Bi-2223초전도 선재의 미세구조와 상전이, 임계 전류 밀도등에 미치는 영향에 대해 고찰하였다. 분말의 입자 크기는 하소 분말을 볼밀을 이용하여 0-48 시간 동안 분쇄하여 조절하였다. 열처리 후 최종 초전도 선재의 전기적 성질은 초기 분말의 입자 크기에 영향을 받는 것으로 나타났으며 분말의 분쇄에 의한 반응성의 증가에 의해 열처리시 2223 상으로의 상전이가 빠르게 일어났고 이차상의 크기와 분율이 감소된 미세구조를 얻을 수 있었다. 그러나 과다한 분쇄에 의한 반응성의 증가에 의해 열처리시 2223상으로의 상전이가 빠르게 일어났고 이차상의 크기와 분율이 감소된 미세구조를 얻을 수 있었다. 그러나 과다한 분쇄는 분말의 비정질화를 유발하여 2223 상으로의 전이를 방해함으로써 선재의 임계 전류 밀도를 감소시키는 결과를 나타내었다.

In the industrial wastewater that occupies a large proportion of river pollution, the wastewater generated in textile, leather, and plating industries is hardly decomposable. Though dyeing wastewater has generally been treated using chemical and biological methods, its characteristics cause treatment efficiencies such as chemical oxygen demand (COD) and suspended solids (SS) to be reduced only in the activated sludge method. Currently, advanced oxidation technology for the treatment of dyeing wastewater is being developed worldwide. Electro-coagulation is highly adapted to industrial wastewater treatment because it has a high removal efficiency and a short processing time regardless of the biodegradable nature of the contaminant. In this study, the effects of the current density and the electrolyte condition on the COD removal efficiency in dyeing wastewater treatment by using electro-coagulation were tested with an aluminum anode and a stainless steel cathode. The results are as follows: ① When the current density was adjusted to 20 A/m2, 40 A/m2, and 60 A/m2 under the condition without electrolyte, the COD removal efficiency at 60 min was 62.3%, 72.3%, and 81.0%, respectively. ② The removal efficiency with NaCl addition was 7.9% higher on average than that with non-addition at all current densities. ③ The removal efficiency with Na2SO4 addition was 4.7% higher on average than that with non-addition at all current densities.

The salt water generated from the salting process of kimchi production is difficult to treat biologically due to very high content of salt. When salt water is treated and discharged, it cannot satisfy the criteria for effluent water quality in clean areas, while resources such as the salt to be recycled and the industrial water are wasted. Therefore, in order to recycle salt water and improve the economy of kimchi production process, a basic study was conducted on the treatment using electrochemical oxidation of organic acids and organic matters existing in large volumes of salt water. The electrochemical treatment of organic matters has advantages over conventional methods such as active carbon absorption process, chemical oxidation, and biological treatment because the response speed is faster and it does not require expensive, harmful oxidizing agents. In this study, the electrochemical oxidation characteristics according to current density and pH were evaluated with acetic, lactic, and formic acids existing in large volumes of salt water. Acetic acid was refractory to electrochemical oxidation regardless of current density, while lactic acid showed high removal efficiency even at low amount of current. Furthermore, formic acid showed the highest current efficiency for the first 20 minutes and its removal rate increased together with the amount of current. In the experiments with the initial pH set to 4, 7, and 10, the removal rate of organic acids tended to be higher at lower pH values. Because NaCl was used as the electrolyte, HOCl was produced at pH 4 and OCl− increased at pH7. The germicidal power of HOCl is about 40-80 times higher than that of OCl−. For this reason, the generation of HOCl with excellent oxidizing power increased at pH 4 and the highest removal rate was achieved. Furthermore, as salt water contains various organic matters, an experiment on organic acid compounds was conducted to see the effects they have on electrochemical oxidation. As a result, it was found that lactic acid and formic acid could be used for simultaneous treatment even when they coexisted, whereas acetic acid is refractory to electrochemical oxidation. Furthermore, lactic acid showed the highest electrochemical treatment efficiency, followed by formic acid, and acetic acid.