• Analytical Science and Technology
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• v.9 no.1
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• pp.1-12
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• 1996

The thermally labile compounds with hydroxyl group generate the [${MNH_4}^+$] ion, [$MH^+$] and [$MH^+-OH$] ion by ion-molecule reaction in LC/TSP/MS. But these ions create the trouble in the estimation of molecular weight of an unknown compound because the margin of [${MNH_4}^+$] ion and [$MH^+$] ion is same to that of [$MH^+$] ion and [$MH^+-OH$] ion. If it is compensated for the results by using of the $CF_3COOD+NH_4OH$ LC eluent, the molecular weight of analyte will be able to be confirmed. And this study was tried to recognize whether the fragment ions of thermally labile compound are generated by electron impact or by thermal degradation in ion source.

• YAKHAK HOEJI
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• v.38 no.2
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• pp.211-217
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• 1994

Copper intoxication and disturbance of copper metabolism induced various oxygen-derived free radicals related damages. The effect of copper ion on xanthine oxidase activity and type conversion of the enzyme which is concerned to generation of reactive oxygen species, was investigated, It was observed that xanthine oxidase activity was increased by addition of copper ion in the reaction mixture in proportional to the concentration of the metal ion until $60\;{\mu}M$, while the enzyme activity was inhibited in higher concentration of copper treatment. On the other hand, xanthine dehydrogenase activity was inhibited by copper ion addition with concentration dependently. Preincubation of enzyme source with $30\;{\mu}M$ of copper ion, which concentration marked increased the xanthine oxidase activity, unchanged the enzyme activity and type conversion compare to control in vitro system. It was also observed that copper induced xanthine oxidase activity and the enzyme type conversion was protected by dithiothreitol and penicillamine. These results indicate that the increment of the type conversion of xanthine oxidase necessarilly need the presence of copper ion in enzyme assay system.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.5
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• pp.106-112
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• 1994

We have developed a large area ion shower doping system with an RF plasma ion source. The ion current density (i.e., doping concentration) increases with RF power and acceleration voltage. Using this technique, we investigated the optimum condition for ion doping of phosphorus in a-Si:H and poly-Si films. The optimum acceleration voltage and doping time are 6KV and 90sec, respectively, in a-Si:H films. Under this condition the electrical conductivity of ion-doped a-Si:H film is obtained ~10$^{-3}$/cm at room temperature. The sheet resistance decreases witnh acceleration voltage in ion-doped poly-Si, and a heavily-doped layer with a sheet resistance of 920$\Omega$/ㅁ is obtained by using ion doping and subsequent activation.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.501-505
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• 2004

The study on the hybrid power source for the IMT2000 application has been presented. The hybrid power source is composed of solar cell, super-capacitor and battery. To compensate for the pulse loader of the IMT2000 application, the super-capacitor is connected through the Lithium-ion battery to absorb the pulse current. The solar cell provides the additional current to compensate for the depleted current. The controller design for the hybrid source has been presented and verified through experiment.

• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.29-32
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• 2002

This paper describes a novel structure of NMOSFET with elevated SiGe source/drain region and ultra-shallow source/drain extension(SDE)region. A new ultra-shallow junction formation technology. Which is based on damage-free process for rcplacing of low energy ion implantation, is realized using ultra-high vacuum chemical vapor deposition(UHVCVD) and excimer laser annealing(ELA).

• Journal of the Korean Vacuum Society
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• v.8 no.3B
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• pp.346-352
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• 1999

Diamond-like carbon (DLC) lims were deposited by using end hall type ion gun. Benzene gas was used for the generation of carbon ions. In order to systematically control the ion energy, we applied to the substrate DC, pulsed DC or 250 kHz medium frequency bias voltage, DLC films of superior mechanical properties of hardness 39$\pm$4 GPa and elastic mudulus 290$\pm$50GPa (2 to 6 times better than those of the films deposited by plasma assisted CVD method) could be obtained. Deposition rate was much higher than when using Kaufman type ion source, which results from higher ion beam current of end hall type ion gun. The mechanical properties and atomic bond structure were independent of the bias voltage type ion gun. The mechanical properties and atomic bond structure were independent of the bias voltage type but intimately related with the magnitude of the bias voltage. With increasing the negative bias voltage, the structure of the films changed to graphitic one resulting in decreased content of three dimensional inter-links. Degradation of the mechanical properties with increasing bias voltage could be thus understood in terms of the content odf three dimensional inter-links.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.306-313
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• 2004

The microwave discharge ion engine generates plasmas of both the main ion source and the neutralizer using 4㎓ microwave without discharge electrodes and hollow cathodes, so that long life and durability against oxygen and air are expected. The MUSES-C “HAYABUSA” asteroid explorer installing four microwave discharge ion engines “$\mu$10s” was launched into deep space by M-V rocket No.5 on May 9, 2003. After vacuum exposure and several runs of baking for reduction of residual gas the ion engine system established the continuous acceleration of the spacecraft toward the asteroid “ITOKAWA”. The Doppler shift measurement of the communication microwave revealed the performance of ion engines, which is 8mN thrust force for a single unit with 3,200sec specific impulse at 23mN/㎾ thrust power ratio. At the end of 2003 the accumulated operational time exceeded 8,000 hour and unit. HAYABUSA will execute the Earth swing-by on June 2004 and arrive at the asteroid in 2005 and return to Earth in 2007.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.95-99
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• 1995

keV ion beam irradiatin for surface modification and thin film growth have been discussed. keV ion beam irradiation in reactive gas environment has been developed for improving wettability of polymer, and for enhancing adhesion to metal film, and adventages of the method have been reviewed. An epitaxial Cu film on Si(100) substrate has been grown by ionized cluster beam and changes of crystallinity and surface roughness have been discussed. Stoichiometric $SnO_2$ films on Si(100) and glass have been grown by a hybrid ion beam Deposition(2 metal ion sources+1 gas ion source), and nonstoichiometric $SnO_2$ films are controlled by various deposition conditions in the HIB. Surface modification for polymer by kev ion irradiation have been developed. Wetting angle of water to PC has been changed from 68 degree to 49 degree with $Ar^+$ irradiation and to 8 degree with $Ar^+$ irradiation and the oxygen environment. Change of surface phenomena in a keV ion beam and characteristics of the grown films are suggested.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8679-8683
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• 2015

Using a surface modification technique, ion beam assisted deposition (IBAD) of Ti thin film it becomes possible to prepare an active ceramic surface to braze $Al_2O_3$-STS304 with conventional Ag-Cu eutectic composition filler metal. Researches on bonding formations at interfaces of ceramic joints were mainly related on the development of filler metals to ceramic, the process parameters, and clarifications of reaction products. From the results, the reactive brazing is a very convenient technique compared to the conventional Mn-Mo method. However melting point of reactive filler is still higher than that of Ag-Cu eutectic and it forms the brittle inter metallic compound. Recently several new approaches are introduced to overcome the main shortcomings of the reactive metal brazing in ceramic-metal, metal vapor vacuum arc ion source was introduced to implant the reactive element directly into the ceramics surface, and sputter deposition with sputter etching for the deposition of active material.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.43-48
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• 2018

In this study, we performed various extraction condition experiments such as types and concentrations of extractants, amounts of extraction sources, pretreatment processes, to optimize the calcium ion extraction for precipitated calcium carbonate (PCC) production. CaO was used as a calcium extraction source, The extraction amount of calcium ions and the particle size of CaO were determined by ICP and SEM results. As a result, 100% calcium ion was extracted when 2 M hydrochloric acid was used as an extractant, and the optimum amount of the extraction source was 6 g. On the other hand, it was confirmed that the reaction time, reaction temperature, particle milling and heat treatment process had no significant effect on the calcium ion extraction amount.