• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.3
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• pp.192-199
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• 1999

During start up and shut down, the generator is rotating at a low speed and copper dusts cause arcing between the turns in the slot. Shorted turns occurred primarily by the movement of these copper dusts between individual windings in the generator rotor. Detection of shorted turns was performed in five gas turbine generators in two combined cycle power plants. Two types of permanent and temporary flux probes were used in this paper. These flux probes have been used to develop a methodology for detecting shorted turns in an operating generator's rotor. The flux probes sense the rotor winding slot leakage flux and produce a voltage proportional to the rate of change of the flux. This pattern of flux variation is the signature unique to each rotor winding. An appropriate waveform analysis technique canidentify the pole location, the slot number, and the number of shorted turns within each slot. Shorted turns in field winding of gas turbine generator(125.7 MVA) were detected to twelve turns on al total 190 turns.

• Transactions on Electrical and Electronic Materials
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• v.15 no.1
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• pp.41-44
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• 2014

Emission properties of the organic light-emitting diodes were investigated with the use of a hole-injection layer of copper(II)-phthalocyanine (CuPc). The manufactured device structure is indium-tin-oxide (ITO) (180 nm)/CuPc (0~50 nm)/N,N'-Bis(3-methylphenyl)-N,N'-diphenylbenzidine (TPD) (40 nm)/tris-(8-hydroxyquinoline) aluminum (III) ($Alq_3$) (60 nm)/Al(100 nm). We investigated the luminescence properties of $Alq_3$ which is affected by the CuPc hole-injection layer. Also, we studied the influence of light-emission properties in the structure of an ITO/CuPc/TPD/$Alq_3$/Al device depending on the several thicknesses of CuPc (0~50 nm) layer. As a result, it was found that the hole injection occurs smoothly in the device with 20 nm thick CuPc layer, and the properties become significantly worse in the device with a CuPc layer thickness higher than 40 nm. We studied the topography and external quantum efficiency depending on the layer thickness of CuPc. Also, we analyzed the electroluminescent characteristics in the low and high-voltage range.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.660-662
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• 2001

This paper describes the problems generated with the use of PWM ASDs with induction motors. The major effect of harmonic voltages and currents in induction motors is increased the heating due to iron and copper losses at harmonic frequencies. The harmonic components thus affect the motor efficiency and developed the torque. In order to investigate the effect of harmonics which is caused by using of nonlinear load at the low voltage system, we set up simple load system and measured the voltage and current. Measurement results show that additional operation of induction motor at the parallel bus in using nonlinear load such as ASD is helpful to the reduction of harmonic current.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.791-800
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• 2010

This paper presents the construction status and the conceptual designs of midium and high level radioactive waste disposal facilities from all around world. For the midium radioactive waste, a shallow disposal using trench or a deep depth disposal are adopted. However, these are rather focusing on the social and cultural point of view than the technical. Meanwhile, the high level radioactive waste is basically disposed in the deep underground. The corresponding ground conditions are usually dense and composed of sedimentary and crystalline rocks mainly with low permeability. A barrier system is made of canister which consists of copper, titanium, and tin. The inner and outer side of the canister are composed of different materials respectively.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1648-1650
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• 1996

In present paper, Cu films $4{\mu}m$, thick were fabricated by dual deposition methods using RF magnetron sputtering on Si wafer. The dependence of the electrical resistivity, adherence, and reflection in Cu films [$Cu_{4-x}$(low resistivity) / $Cu_x$(high adherence) / Si- wafer] on the x thickness have been investigated. Cu films of $4{\mu}m$ thickness formed with dual deposition methods had the low electrical resistivity of about $2.6{\mu}{\Omega}{\cdot}cm$ and high adherence of about 700g/cm. In conclusion, it is possible for these films to be used for micro-devices.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.6
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• pp.845-852
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• 2001

The characteristics of evaporation cooling of single droplet on a heated surface were studied experimentally. The two kinds of heater modules were tested to measure cooling characteristics of metal surface (high conductivity) and Teflon surface (low-energy surface, low conductivity). The results showed that time averaged heat flux during droplet evaporation increased exponentially with initial surface temperatures of brass, copper and steel. The heat flux and evaporation time did not varied with metal conductivities. However, the temperature drop after the deposition of droplet was larger on Teflon than on the metals. Thus, the correlation of interface temperature between liquid droplet and metal surface was proposed as a function of the initial surface temperature of heating materials, which could be applied to both metal and non-metal ones.

• Bulletin of the Korean Chemical Society
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• v.18 no.7
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• pp.706-710
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• 1997

Isotope ratios of K, Ca, Cr and Fe are measured at cool plasma condition generated using high carrier flow rate and relatively low RF power of 900 W. Background molecular ions are suppressed to below 100 counts which give isobaric interference to the analytes. The background ions show different attenuation characteristics at increased carrier flow rate and hence for each element different carrier flow rate should be used to measure isotope ratios without isobaric interference. Isotope ratios are measured at both scan and peak-hopping modes and compared with certified or accepted ratios. The measured isotope ratios show some mass discrimination against low mass due to low ion energy induced from a copper shield to eliminate capacitive coupling of plasma with load coil.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.166-169
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• 2003

In this study, we evaluated the characteristics by the addition of 3 different kinds of nonionic surfactant to improve the dispersion stability of slurries. Slurry stability is an issue in any industry in which settling of particles can result in poor performance. So we observed the variation of particle size and settling rate when the concentration and addition time of surfactant are changed. When the surfactant is added after milling process, the particle size and pH became low. It is supposed that the particle agglomeration was disturbed by adsorption of surfactant on alumina abrasive. The settling rate was relatively stable when nonionic surfactant is added about 0.1~1.0 wt%. When molecular weight(MW) is too small like Brij 35, it was appeared low effect on dispersion stability. Because it can't prevent coagulation and subsequent settling with too small MW. The proper quality of MW for slurry stability was presented about 500,000. Consequently, the addition of nonionic surfactant to alumina slurry has been shown to have very good effect on slurry stabilization. If we apply this results to copper CMP process, it is thought that we will be able to obtain better yield.

• Korean Journal of Microbiology
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• v.51 no.1
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• pp.7-13
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• 2015

Hydrotrope-combined copper (HCC) is a copper ($Cu^{2+}$)-based algicide, which is combined with a hydrotrope that keeps copper ion in solution to improve performance. This study assessed the growth inhibition effect of HCC against Microcystis aeruginosa which is one of the most common toxic cyanobacterium in eutrophic freshwater environment. Various HCC doses, ranging from 5.5 to $550{\mu}g/L$ as $Cu^{2+}$, were applied to either BG-11 or 1/4 diluted medium with low- or high-inoculum density of M. aeruginosa. Growth inhibition was monitored based on a decrease in chlorophyll-a content in culture medium during the incubation. Results showed that HCC significantly inhibited the growth of M. aeruginosa in a dose-dependent manner. In case of 1/4 diluted BG-11 medium, HCC dose as low as $5.5{\mu}g$ $Cu^{2+}/L$ completely inhibited the production of chlorophyll-a by M. aeruginosa. It was found that HCC did not induce any significant release of microcystin-LR from M. aeruginosa. Acute toxicity of HCC was tested using Daphnia magna, and the 24-h $EC_{50}$ value was 0.30 mg/L as $Cu^{2+}$ which was much higher than the actual inhibition dose. Ames test was performed using Salmonella enterica serovar Typhimurium TA100, and HCC showed no increase in the number of revertant colonies. The result suggested that HCC does not have any mutagenic potential in the aquatic environment. In addition, no genotoxic effect of HCC was also confirmed based on the SOS ChromoTest using Escherichia coli PQ37. Therefore, HCC could be used as a relatively safe and effective pre- and post-treatment agent to control hazardous algal blooming in aquatic environments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3517-3523
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• 2010

Single exposure dual X-ray imaging can be used to separate soft and dense-material images for medical and industrial applications. This study keep focusing baggage inspection system(BIS) specifically. New detector modules for single exposure dual X-ray imaging are consisted of low energy detector (LED) and high energy detector (HED). First, the optimized thickness of copper filter coupled HED to separate low energy and high energy was simulated by the given X-ray energy (140 kVp, 1 mA) using Monte Carlo simulation codes, MCNPX. So as a result of simulation, the copper filter thickness is 0.7 mm. For the design of PIN photodiode, ATLAS device simulation tool was used. 16 channels PIN photodiode of 1.5 mm ${\times}$ 3.2 mm for Dual X-ray imaging detector was fabricated in the process of ETRI. And its dark current and quantum efficiency, terminal capacitance were measured. It was proven that the Lanex Fast B coupled HED were a sufficient candidate to replace the CsI(Tl) commerced in dual X-ray system, since these give a strong signal, overcoming system noise. Finally dual X-ray image was acquired through correction of the LED X-ray Image and the HED X-ray Image.