• 통합자연과학논문집
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• 제3권4호
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• pp.210-214
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• 2010

Relationship between etch current and morphology and porosity of porous silicon (PS) has been investigated. The gravimetric method is applied to measured the porosity of PS. As the current density increase, the silicon dissolution rate increases, resulting in a higher porosity and etching rate. The result shows that linear dependence of PS porosity and etching rate as a function of current density. The morphology of porous silicon was investigated by using cold field emission scanning electron micrograph (FE-SEM). The size of pores formed during anodization is predominantly controlled by the current density, with an increase in the pore size corresponding to an increase in the current density.

• 한국표면공학회지
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• 제42권4호
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• pp.145-151
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• 2009

Nanocrystalline Cu thin films for FCCL were electrodeposited from sulfate baths to investigate systematically the influences of current density, solution pH on current efficiency, residual stress, surface morphology, and microstructure of thin Cu films. Current efficiencies were measured to be approximately 100%, irrespective of the applied current density and solution pH. But these influenced residual stress, surface morphology, XRD pattern, and grain size of electrodeposited Cu thin film. The residual stress decreased with decreasing the surface roughness, but increased with increasing the fcc(111) peak strength of XRD patterns.

• 소성∙가공
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• 제27권3호
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• pp.177-183
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• 2018

The influence of electric current on the springback characteristics of AZX311 magnesium alloy and martensitic steel after V-bending test is investigated. Various pulsed electric currents are applied into the specimens followed by a V-bending test, and the changes in the springback angle are measured. In order to evaluate not only the thermal effect but also the athermal effect of electric current on the springback angle, the temperature rises resulting from the applied electric current are measured for all test conditions. As a result, it was found that the springback is significantly decreased as the current density increases. As for the martensitic steel, since the dislocation recovery immoderately occurs at a high electric current density condition of $80A/mm^2$, the optimal current density condition should be required.

• 한국표면공학회지
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• 제52권2호
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• pp.72-77
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• 2019

To study the characteristics of AC driven OLED, we fabricated the fluorescent OLEDs and analyzed the electroluminescence characteristics of OLEDs with AC negative voltage. The luminance and the current density of the OLED decreased, and the number and size of the dark spots increased in proportion to the duration time and level of the applied AC negative voltage. The current efficiency of the OLED was improved when high AC negative voltage was applied within a short time. When the AC negative voltage of 10 V was applied for 1 minute, the efficiency was improved by 12.4%. Also, the degradation of luminance and current efficiency due to the duration of light emission was improved in the case of OLED applied for 1 minute with 10 V AC negative voltage. These are expected as a result of the improvement of the leakage current characteristics by eliminating the short-circuit region formed by the defect of the OLED at the AC negative high voltage. As a result, the continuous application of AC negative voltage reduced the luminance and the current density of OLED, but the temporary application of AC negative voltage with the proper time and voltage could improve the efficiency and lifetime of OLED.

• Membrane and Water Treatment
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• 제11권3호
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• pp.217-222
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• 2020

An electrochemical oxidation process was applied to remove cyanide (CN^-) from real plating wastewater. CN^- removal efficiencies were investigated under various operating factors: current density and electrolyte concentration. Electrolyte concentration positively affected the removal of both CN^- and Chemical Oxygen Demand (COD). As the electrolyte concentration increased from 302 to 2,077 mg Cl^-/L, removal efficiency of CN^- and COD increased from 49.07% to 98.30% and from 23.53% to 49.50%, respectively, at 10 mA/㎠. Current density affected the removal efficiency in a different way. As current density increased at a fixed electrolyte concentration, CN^- removal efficiency increased while COD removal efficiency decreased, this is probably due to lowered current efficiency caused by water electrolysis.

• International Journal of Precision Engineering and Manufacturing
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• 제2권1호
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• pp.18-25
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• 2001

Electrolytic polishing is the anodic dissolution process in the transpassive state. It removes non-metallic inclusion and improves mechanical and corrosion resistance of stainless steel. If there is a Bailby layer, it will be removed and the true structure of the surface will be restored. Electrolytic polishing is normally used to remove a very thin layer of material from the surface of metal object. A new electrolyte composed of phosphoric, sulfuric and distilled water has been developed in this study. Two current density, high & low current density regions, have been applied in this study. In this study, In the region of high current density, there is no plateau region but excellent electrolytic polishing effect can be accomplished in short machining time because material removel process and leveling process occur simultaneously. In the low current density region, there can be found plateau region. The material removal process and leveling process occur successively. The aim of this work is to determine electrolytic polishing for stainless steel in terms of high & low current density and workpiece surface roughness.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.276-279
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• 2000

When high temperature superconducting tapes is fabricated using the PIT (Powder In Tube) method, the length of HTS tapes is increased more than 500 ${\sim}$ 1,000 times of initial powder packed billet. On mechanical processing, heterogeneous properties between the ceramic superconducting core and Ag/Ag alloy sheath occur the non-uniformity deformation as like sausaging that deteriorate the critical current properties of HTS tapes. In this study, we investigated the workability of Bi-2223/Ag/Ag alloy sheath tapes fabricated by the PIT method involving a number of different mechanical processes, multi drawing and rolling. In order to obtain the high critical current density and high uniformity of Bi-2223/Ag sheath tapes, the influences of powder packing density, drawing die angle and rolling parameters were studied. We found that the roll diameter is an important variable in the rolling process, as critical current of tapes rolled using 250 mm rolls was higher than that using 150 mm rolls.

• 한국전기전자재료학회논문지
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• 제24권6호
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• pp.504-509
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• 2011

The conducting current of non-uniform plasma immersed electrode consists of ion current and secondary electron emission current caused by the impinging ion current. The ion current is determined by the ion dose passing through the sheath in front of electrode and the ion distribution in front of the electrode plays an important role in the secondary electron emission. The investigation of the distributed plasma and secondary electron effect on electrode ion current was carried out as the stainless steel electrode plugged with quartz tube was immersed in the inductively coupled Ar plasma using the antenna powered by 1 kw and the density profile was measured. After that, the negative voltage was applied by 1 kV~6 kV to measure the conduction current for the analysis of ion current.

• 멤브레인
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• 제12권3호
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• pp.171-181
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• 2002

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.

• 대한전자공학회논문지TE
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• 제37권2호
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• pp.17-24
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• 2000

In this paper, the stress and transient currents associated with the on and off time of applied voltage were used to measure the density and distribution of high voltage stress induced traps in thin silicon oxide films. The transient currents were due to the discharging of traps generated by high stress voltage in the silicon oxides. The trap distributions were relatively uniform new both cathode and anode interface. The trap densities were dependent on the stress polarity. The stress generated trap distributions were relatively uniform the order of 1011~1021[states/eV/cm2] after a stress voltage. It appear that the stress and transient current that flowed when the stress voltage were applied to the oxide was caused by carriers tunneling through the silicon oxide by the high voltage stress generated traps.