• Journal of the Semiconductor & Display Technology
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• v.10 no.3
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• pp.15-19
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• 2011

The performance of the DRAM is strongly dependent on the purity and surface roughness of the TIT (TiN/Insulator/ TiN) capacitor electrodes. Hence, in the present study, we evaluate the effects of organic contamination and change of surface roughness on the cylindrical TIT capacitor electrodes during the wet cleaning process by various analytical techniques such as TDMS, AFM, XRD and V-SEM. Once the sacrificial oxide and PR (Photo Resist) are removed by HF, the organic contamination and surface oxide films on the bottom Ti/TiN electrode become visible. With prolonged HF process, the surface roughness of the electrode is increased, whereas the amount of oxidized Ti/TiN is reduced due to the HF chemicals. In the 80nm DRAM device fabrication, the organic contamination of the cylindrical TIT capacitor may cause defects like SBD (Storage node Bridge Defect). The SBD fail bit portion is increased as the surface roughness is increased by HF chemicals reactions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.3
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• pp.74-82
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• 2001

To reduce the maintenance expense and the possibility of electric outage and/or accident, which causes the decrease in stability and reliability of transmission/distribution line, most of all, accurate measurement for the degree of contamination should be preceded. But the conventional method (brush wiping method), which is recommended in IEC 60815, has sow significant problem in the aspect of man power, expense, error, and so forth. In this investigation, we purpose the development of a new type automatic measuring apparatus, which could measure the degree of contamination on the surface of insulator in outdoor condition. To design and evaluate the apparatus, a FLUX 2D is used, and various laboratory tests, artificial contamination tests, were carried to proof the actual performance. With the result of these effort, we can get the meaningful conclusion to develope a new type automatic apparatus for contamination measurement.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.2
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• pp.317-321
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• 2021

As the large-scale renewable energy power plant increases, the high-capacity and compact Energy Storage System (ESS) is required. However, this trend could reduce the insulation reliability of ESS. In this study, the surface flashover characteristics for four types of solid insulators are investigated in the uniform electric field with AC and Lightning Impulse (LI) voltage waveforms under various contamination levels. In addtion, insulator surfaces are compared based on the contact angle before and after surface flashover. The experimental results show that AC flashover voltage is dependent on the materials and the contamination level, but LI flashover voltage is only associated with the contamination level. Especially, AC flashover voltage of PC (PolyCarbonate) is higher than that of other insulators, which is associated with the unique and sequential creepage discharge propagation pattern of PC. The localized discharges on the surface of PC form corresponding tracking points. Then, the interconnected trackings result in the complete flashover. This flashover patterns degrade the surface of PC much more than that of epoxy and Bulk Molding Compoud (BMC). Thus, the contact angle of PC is significantly reduced compared to that of other insulators. The increased hydrophilicity in the surface of PC enhances the insulator surface conductivity.

• Economic and Environmental Geology
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• v.34 no.1
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• pp.89-104
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• 2001

The Chonju and Samchun streams are passing though Chonju city and several contamination sources are located along these streams. The Samchun stream joins the Chonju stream in the Gosapyeong waste disposal site and the Chonju stream finally joins to the Mankyeong River. The objectives of this study are to determine the state and sources of contamination for heavy metals and anions in the Chonju and Samchun streams and to evaluate the effect of these streams on the contamination of the Mankyeong River. In order to select sampling locations, a stratified random sampling method was used. These streams was divided into several parts according to the expected contamination state, and samples were selected randomly from these parts. Generally, the water qualities of these streams were generally below the Drinking Water Level at the time of sampling in various heavy metals and anions. However, the levels of AI, Fe, $NH_{3}-N,Cl^{-}$, Cl- in these streams could be higher during dry season due to continuous inputs from various contamination sources. This study identified several contamination sources for these streams; two waste disposal sites along these streams for Fe, Mn, AI, Zn and $Cl^{-}$, the Chonju Waste Water Treatment Plant for Zn, Mn, $Cl^{-}$, $SO_{4}S$, $NO_{2}N$, and $NH_{3}-N$ and the untreated sewages for AI, Zn, Mn, $Cl^{-}$, $SO_{4}S$, $NH_{3}-N$ and $PO_{4}^{2-}$. This study also revealed that the Chonju stream itself is an important contamination source for Fe, Mn, $Cl^{-}$ and $SO_{4}S$ in the Mankyung River.

• Journal of Radiation Industry
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• v.5 no.2
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• pp.185-189
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• 2011

As nuclear industry has been developed, a various types of radiological contamination has occurred. After 9.11 terror in U.S.A., it has been concerned that terrorists' active area has been enlarged to use nuclear or radioactive substance. Recently, the most powerful earth-quake stroke, which triggered a massive tsunami in Japan and then Fukushima nuclear power plant reactor has suffered from a serious accident in history. The Fukushima reactor accident has occurred an anxiety of radiation leaks and about 170,000 people have been evacuated from the accidental area near the nuclear power plant. For these reasons, a social chaos can be occurred if radiological contamination occurs to the supply system for the drinking water. As such, the establishment of the radiation monitoring system for the city main water system is compelling for the national security. In this study, a feasibility test of radiation monitoring system which consists of unified hybrid-type radiation detectors was experimented for multi detection system by using gamma-ray imaging. The hybrid-type radiation sensors were fabricated with CsI(Tl) scintillators and photodiodes. A preamplifier and amplifier was also fabricated and assembled with the sensor in the shielding case. For the preliminary test of detection of radiological contamination in the river, multi CsI(Tl)-PIN photodiode radiation detectors and $^{137}Cs$ gamma-ray source were used. The DAQ was done by Linux based ROOT program and NI DAQ system with Labview program. The simulated contamination was assumed to be occurred at Gapcheon river in Daejeon city. Multi CsI(Tl)-PIN photodiode radiation detectors were positioned at the Gapcheon river side. Assuming that the radiological contaminations flows in the river the $^{137}Cs$ gamma-ray source has been moved and then, the contamination region was reconstructed.

• Analytical Science and Technology
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• v.31 no.3
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• pp.122-133
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• 2018

In this study, groundwater quality data measured for 11 years from 2006 to 2016 were analyzed statistically for 101 civil defense emergency water supply facilities (CDEWSF) in the Gwangju area. The contamination level was quantified into four grades by using excess drinking water quality standards, average concentration analysis, and tendency analysis results for each facility. On the basis of this approach, the groundwater contamination degree of each item was evaluated according to land use status, installation year, depth, and geological distribution. The contamination grade ratios, which were obtained by analyzing three contamination indicators (water quality exceeded frequency, average concentration analysis, and trend analysis) for 15 items on statistically significant of civil defense emergency water was relatively high, in the order of Turbidity (51.5 %) > Color (32.7 %) > Nitrate nitrogen (28.7 %) > Hardness (25.7 %). As a result of the contamination grade analysis, except for the items of Turbidity, Color, and Nitrate nitrogen, the contamination levels were distributed in various degrees from "clean (0)" to "seriously contaminated (3)." Regarding the contamination grade of 12 items, 25 % of the total were classified as "possibly contaminated (1)," and 75 % were rated "clean (0)." The four items (Turbidity, Color, Nitrate nitrogen, and Hardness) for which contamination indication rate were evaluated as "high" by the were visualized on a contamination map.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.24-33
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• 2000

The effect of particulate contamination on friction and wear between a negative-pressure picoslider / tri-pad nanoslider and laser-textured disk was studied. Particles of different concentration were injected at the head-disk interface consisting of disks with various textures and slider types at different speed. Durability increased and coefficient of friction decreased as the disk speed increased in a contaminated environment. Frictional characteristics and durability in the data zone were better for those of the laser-textured zone. It was also found that durability of head-disk interface (HDI)decreased as the particle concentration increased. The interface durability with a picoslider was better than that with a nanoslider at any condition in a contaminated environment. Based on the test results, mechanisms were proposed to explain the reasons why durability with a picoslider was superior to that with a nanoslider.

• Tribology and Lubricants
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• v.16 no.6
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• pp.469-476
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• 2000

The effect of particulate contamination on the friction and wear between a negative-pressure picoslider/tri-pad nanoslider and laser-textured disk was studied. Particles of different concentration were injected at the head-disk interface consisting of disks with various textures and slider types at different speed. Durability increased and coefficient of friction decreased as the disk speed increased in a contaminated environment. Frictional characteristics and durability in the data Bone were better than those in the laser-textured zone. It was also found that durability of head-disk interface (HDI) decreased as the particle concentration increased. The interface durability with a picoslider was better than that with a nanoslider at any condition in a contaminated environment. Based on the test results, mechanisms were proposed to explain the reasons why durability with a picoslider was superior to that with a nanoslider.

• Journal of the Semiconductor & Display Technology
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• v.15 no.2
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• pp.70-73
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• 2016

Previously proposed contamination detecting sensor was revisited for the investigation of the liquid tendency. Experiments revealed different output voltages for several kinds of liquid input, but showed same values for various flow rates of each liquid. The transmittance of the liquid was measured, and it is well correlated with the voltages. Linearity in values and the compensation of the sensor to sensor deviation were tried to obtain. And, long term test was performed as attached at the manufacturing equipment in the field.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.2
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• pp.46-52
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• 2004

Numerous connectors are used in automobiles for transmission of electrical signals across various electro-mechanical components. The connectors must operate with high reliability in order to minimize failures due to signal degradation. In this work, the effects of contamination at the contact interface of connectors used fur automobile crankshaft position sensor on the impedance change were investigated. An experimental set-up was built to simulate the electrical signal transmitted from the sensor to the engine control unit through a connector. Output from the connector was investigated using connectors contaminated with engine block residues and water droplets. It was found that slight contamination of the connectors could lead to significant signal degradation which can lead to engine failure. Also, the effect of water in the connector altered the signal severely. However, the signal gradually regained the original state as the water evaporated from the interface.