• Korean Journal of Materials Research
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• v.22 no.4
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• pp.202-206
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• 2012

$CoSi_2$ was formed through annealing of atomic layer deposition Co thin films. Co ALD was carried out using bis(N,N'-diisopropylacetamidinato) cobalt ($Co(iPr-AMD)_2$) as a precursor and $NH_3$ as a reactant; this reaction produced a highly conformal Co film with low resistivity ($50\;{\mu}{\Omega}cm$). To prevent oxygen contamination, $ex-situ$ sputtered Ti and $in-situ$ ALD Ru were used as capping layers, and the silicide formation prepared by rapid thermal annealing (RTA) was used for comparison. Ru ALD was carried out with (Dimethylcyclopendienyl)(Ethylcyclopentadienyl) Ruthenium ((DMPD)(EtCp)Ru) and $O_2$ as a precursor and reactant, respectively; the resulting material has good conformality of as much as 90% in structure of high aspect ratio. X-ray diffraction showed that $CoSi_2$ was in a poly-crystalline state and formed at over $800^{\circ}C$ of annealing temperature for both cases. To investigate the as-deposited and annealed sample with each capping layer, high resolution scanning transmission electron microscopy (STEM) was employed with electron energy loss spectroscopy (EELS). After annealing, in the case of the Ti capping layer, $CoSi_2$ about 40 nm thick was formed while the $SiO_x$ interlayer, which is the native oxide, became thinner due to oxygen scavenging property of Ti. Although Si diffusion toward the outside occurred in the Ru capping layer case, and the Ru layer was not as good as the sputtered Ti layer, in terms of the lack of scavenging oxygen, the Ru layer prepared by the ALD process, with high conformality, acted as a capping layer, resulting in the prevention of oxidation and the formation of $CoSi_2$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.3
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• pp.406-412
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• 2018

This paper describes the fabrication process of laser induced graphene (LIG) and its transfer method on to a flexible and stretchable PDMS substrate. By irradiating CO2 laser on a polyimide(PI) film surface, a localized high temperature is created, resulting in a three-dimensional porous graphene network structure with good conductivity. This LIG electrode is relatively easy to fabricate and since it is very weak the LIG electrode was transferred to a flexible PDMS substrate to increase the sturdiness as well as possible use in flexible applications. Sheet resistance, thickness, and electrochemical activity of the fabricated in-situ LIG electrodes have been examined and compared with the LIG electrodes after transferring to PDMS elastomer. The properties of the LIG electrodes were also examined depending on the $CO_2$ laser power. As the irradiated laser power increased, the LIG electrode resistance decreases and the LIG electrode thickness increased. At 4.8 W of laser power, the average sheet resistance and thickness of the fabricated LIG electrodes were approximately $31.7{\Omega}/{\Box}$ and $62.67{\mu}m$, respectively. Moreover, the electrochemical activity of the fabricated LIG electrode at 4.8 W of laser power showed a high oxidation current of $28.2{\mu}A$ after transferring to PDMS.

• Journal of the Korean Applied Science and Technology
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• v.34 no.2
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• pp.376-381
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• 2017

We were investigated by cyclic voltammetry to the stability through the electrochemical characteristics of Langmuir-Blodgett films mixed with myristic acid and stearic acid. Fatty acid mixture monolayer LB films was deposited by the LB method on the indium tin oxide(ITO) glass. The electrochemical properties was measured by cyclic voltammetry with a three-electrode system in 0.01 N $NaClO_4$ solution. The measuring range is continuously oxidized to 1650 mV, with an initial potential of -1350 mV was reduced. Scanning rates of 50, 100, 150, 200, and 250 mV/s was set. As a result, LB monolayer films of fatty acid mixture was appeared on irreversible processes by the oxidation current from the cyclic voltammogram. Diffusion coefficient (D) of fatty acid mixture was calculated $7.9{\times}10^{-2}cm^2s^{-1}$ at 0.01 N $NaClO_4$ solution.

• Korean Journal of Food Science and Technology
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• v.20 no.1
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• pp.1-5
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• 1988

Changes in the quality characteristics of three sizes of boiled-dried anchovies packaged in kraft paper laminated with 0.03 mm PE film during storage for six months at $5^{\circ}C$ were studied. In case of Dae-myul (78-80mm), the reaction of thiobarbituric acid, browning rate of lipid oxidation and Hunter-Scale color values. L, a, and b, were higher than those in Joong-myul (45-49 mm) or So-myul (30-34 mm). Organoleptic evaluation suggests that boiled-dried anchovy be good in sequence as So-myul, Joong-myul and Dae-myul. Shelf life of Dae-myul was half times lower than that of Joong-myul or So-myul. Regression equation for the sensory score prediction with lipid oxidative browning was determined.

• Toxicological Research
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• v.34 no.1
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• pp.49-53
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• 2018

Cyclohexanone ($C_6H_{10}O$, CAS No. 108-94-1) is a colorless oily liquid obtained through the oxidation of cyclohexane or dehydrogenation of phenol. It is used in the manufacture of adhesives, sealant chemicals, agricultural chemicals, paint and coating additives, solvent, electrical and electronic products, paints and coatings, photographic supplies, film, photochemicals, and as an intermediate in nylon production. Owing to the lack of information on repeated inhalation toxicity of cyclohexaone, in this study, we aimed to characterize the subacute inhalation toxicity. B6C3F1 mice were exposed to 0, 50, 150, and 250 ppm of cyclohexanone for 6 hr/day, 5 days/week for 4 weeks via whole-body inhalation in accordance with the OECD Test Guideline 412 (subacute inhalation toxicity: 28-day study). Mortality, clinical signs, body weights, food consumption, hematology, serum biochemistry, organ weights, as well as gross and histopathological findings were evaluated between the control and exposure groups. No mortality or remarkable clinical signs were observed during the study. No adverse effects on body weight, food consumption, hematology, serum biochemistry, and organ weights, gross or histopathological lesions were observed in any male or female mice in any of the exposure groups, although some statistically significant changes were observed in organ weights. We concluded that no observable adverse effect level (NOAEL) is above 250 ppm in mice exposed to cyclohexanone for 6 hr/day for 5 days/week.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.1
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• pp.54-63
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• 2010

Recently, as the function of largest supplier of biomass for "low carbon green growth", the necessity for systematic management of afforestation areas is emphasizing. The forestation of seedling, besides the afforestation cost itself, is required some additional follow-up management costs, like mowing and fertilizing of forestation area, and removal of bindweed. The mulching mat for afforestation seedlings is available for rooting of little seedlings as well as initial forestation expenses. Mulching technique is also used to control soil temperature and moisture by covering the surface of ground. In this study, the paper based-mulching film coated with biodegradable polymer and functional additive was specially produced using laboratory bar coater, and analyzed for its degradable behavior. Coating colors were prepared by dissolving PE (polyester) 80 % and PLA(polylactic acid) 20 % in chloroform and finally applied to handsheet prepared by preceding study conditions. Base paper and polymer-coated paper were artificially aged by 2 kinds of degradation methods, which are soil degradation by microorganism and light degradation by 257 nm UV wavelengths. Strength property, oxidation index and morphological property were evaluated by reduction rates of tensile strength, FTIR spectra ratio of carboxyl and carbonyl group and SEM micrograph. As these results, polymer coated-paper was superior to base paper in degradation behaviors, having results with lower reduction rate of strength properties.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.6 s.183
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• pp.166-173
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• 2006

In this study, a probe array has been developed for use in a data storage device that is based on scanning probe microscope (SPM) and MEMS technology. When recording data bits by poling the PZT thin layer and reading them by sensing its piezoresponse, commercial probes of which the tip heights are typically shorter than $3{\mu}m$ raise a problem due to the electrostatic forces occurring between the probe body and the bottom electrode of a medium. In order to reduce this undesirable effect, a poly-silicon probe with a high aspect-ratio tip was fabricated using a molding technique. Poly-silicon probes fabricated by the molding technique have several features. The tip can be protected during the subsequent fabrication processes and have a high aspect ratio. The tip radius can be as small as 15 nm because sharpening oxidation process is allowed. To drive the probe, electrostatic actuation mechanism was employed since the fabrication process and driving/sensing circuit is very simple. The natural frequency and DC sensitivity of a fabricated probe were measured to be 18.75 kHz and 16.7 nm/V, respectively. The step response characteristic was investigated as well. Overshoot behavior in the probe movement was hardly observed because of large squeeze film air damping forces. Therefore, the probe fabricated in this study is considered to be very useful in probe-based data storages since it can stably approach toward the medium and be more robust against external shock.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.3
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• pp.139-144
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• 2003

A flat type micro gas sensor was fabricated on the p-type silicon wafer with low stress Si$_3$N$_4$, whose thickness is 2 ${\mu}{\textrm}{m}$, using MEMS technology. WO$_3$ thin film as a sensing material for detection of NO$_2$ gas was deposited using a tungsten target by sputtering method, followed by thermal oxidation at several temperatures (40$0^{\circ}C$-$600^{\circ}C$) for one hour. NO$_2$ sensitivities were investigated for the WO$_3$ thin films with different annealing temperatures. The highest sensitivity was obtained for the samples annealed at $600^{\circ}C$ when it was operated at 20$0^{\circ}C$. The results of XRD analysis showed the annealed samples had polycrystalline phase mixed with triclinic and orthorhombic structures. The sample exhibits higher sensitivity when the system has less triclinic structure. The sensitivities, $R_{gas}/R_{air},$ operating at 20$0^{\circ}C$ to 5 ppm NO$_2$ of the sample annealed at $600^{\circ}C$ were approximately 90.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1232_1233
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• 2009

Paraquat is well-known to cause hepatotoxic responses in human and other mammal species. In solution, it forms free radicals and charge-transfer complex of which formation plays an important role in determination of its biological activity in the presence of various anions. The HepG2 cells were cultured onto a quartz crystal sensor which is possible to detect the density and a viscosity changes using the resonance frequency (F) and the resonance resistance (R). The plot of F-R diagram is able to explain the rheological change of cells onto the surface of the quartz crystal sensor. In this paper, we investigated the physical properties of the HepG2 cells cultured onto a ITO electrode of the quartz crystal sensor according to the paraquat injection at various concentrations (100 mM, 10 mM, 1 mM). We also observed the morphological changes with a micro CCD camera, simultaneously. The HepG2 cells were cultured onto the ITO electrode surface of the quartz crystal modified a collagen film in $CO_2$ incubator. After the paraquat injection, we observed the changes of the morphologies by the micro CCD camera depending on time and analyzed the physical changes of cells on the electrode surface of quartz crystal using F-R diagram. From all results, we proved the effect of paraquat at various concentrations which is led to an apoptosis such as weakening and death of the cells by oxidation and reduction reaction that were produced the superoxide anions and other free radicals.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.141-145
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• 2007

Due to their excellent catalytic activity with respect to methanol oxidation on platinum at low temperature, platinum nanosized catalysts have been a topic of great interest for use in direct methanol fuel cells (DMFCs). Since pure platinum is readily poisoned by CO, a by-product of methanol electrooxidation, and is extremely expensive, a number of efforts to design and characterize Pt-based alloy nanosized catalysts or Pt nanophase-support composites have been attempted in order to reduce or relieve the CO poisoning effect. In this review paper, we summarize these efforts based upon our recent research results. The Pt-based nanocatalysts were designed by chemical synthesis and thin-film technology, and were characterized by a variety of analyses. According to bifunctional mechanism, it was concluded that good alloy formation with $2^{nd}$ metal (e.g., Ru) as well as the metallic state and optimum portion of Ru element in the anode catalyst contribute to an enhanced catalytic activity for methanol electrooxidation. In addition, we found that the modified electronic properties of platinum in Pt alloy electrodes as well as the surface and bulk structure of Pt alloys with a proper composition could be attributed to a higher catalytic activity for methanol electooxdation. Proton conducting contribution of nanosized electrocatalysts should also be considered to be excellent in methanol electrooxidation (Spillover effect). Finally, we confirmed the ensemble effect, which combined all above effects, in Pt-based nanocatalsyts especially, such as PtRuRhNi and $PtRuWO_{3}$, contribute to an enhanced catalytic activity.