• Journal of Information Display
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• v.2 no.4
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• pp.1-7
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• 2001

This paper investigates the characteristics of a newly developed high density hollow cathode plasma(HCP) system and its application for the etching of silicon wafers. We used $SF_6$ and $O_2$ gases in the HCP dry etch process. This paper demonstrates very high plasma density of $2{\times}10^{12}cm^{-3}$ at a discharge current of 20 rna, Silicon etch rate of 1.3 ${\mu}m$/min was achieved with $SF_6/O_2$ plasma conditions of total gas pressure of 50 mTorr, gas flow rate of 40 seem, and RF power of200W. This paper presents surface etching characteristics on a crystalline silicon wafer and large area cast type multicrystlline silicon wafer. We obtained field emitter tips size of less than 0.1 ${\mu}m$ without any photomask step as well as with a conventional photolithography. Our experimental results can be applied to various display systems such as thin film growth and etching for TFT-LCDs, emitter tip formations for FEDs, and bright plasma discharge for PDP applications. In this research, we studied silicon etching properties by using the hollow cathode plasma system.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.1
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• pp.41-46
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• 2006

Ubiquitous location based services, offer helpful services anytime and anywhere by using real-time location information of objects based on ubiquitous network. Particularly, autonomous mobile robots can be a solution for various applications related to ubiquitous location based services, e.g. in hospitals, for cleaning, at airports or railway stations. However, a meaningful and still unsolved problem for most applications is to develop a robust and cheap positioning system. A typical example of position measurements is dead reckoning that is well known for providing a good short-term accuracy, being inexpensive and allowing very high sampling rates. However, the measurement always has some accumulated errors because the fundamental idea of dead reckoning is the integration of incremental motion information over time. The other hand, a localization system using RFID offers absolute position of robots regardless of elapsed time. We construct an absolute positioning system based on RFID and investigate how localization technique can be enhanced by RFID through experiment to measure the location of a mobile robot. Tags are placed on the floor at 5cm intervals in the shape of square in an arbitrary space and the accuracy of position measurement is investigated . To reduce the error and the variation of error, a weighting function based on Gaussian function is used. Different weighting values are applied to position data of tags since weighting values follow Gaussian function.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.4
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• pp.298-304
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• 2021

This study aimed to determine the applicability of drones and air quality sensors in environmental monitoring of air pollutant emissions by developing and testing two new methods. The first method used orthoimagery for precise monitoring of pollutant-emitting facilities. The second method used atmospheric sensors for monitoring air pollutants in emissions. Results showed that ground sample distance could be established within 5 cm during the creation of orthoimagery for monitoring emissions, which allowed for detailed examination of facilities with naked eyes. For air quality monitoring, drones were flown on a fixed course and measured the air quality in point units, thus enabling mapping of air quality through spatial analysis. Sensors that could measure various substances were used during this process. Data on particulate matter were compared with data from the National Air Pollution Measurement Network to determine its future potential to leverage. However, technical development and applications for environmental monitoring of pollution-emitting facilities are still in their early stages. They could be limited by meteorological conditions and sensitivity of the sensor technology. This research is expected to provide guidelines for environmental monitoring of pollutant-emitting facilities using drones.

• Microbiology and Biotechnology Letters
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• v.40 no.2
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• pp.117-127
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• 2012

The beneficial effects of adipose-derived stem cell conditioned media (ADSC-CM) for skin regeneration have previously been reported, despite the precise mechanism of how ADSC-CM promotes skin regeneration remaining unclear. ADSC-CM contains various secretomes and this may be a factor in it being a good resource for the treatment of skin conditions. It is also known that ADSC-CM produced in hypoxia conditions, in other words Advanced Adipose-Derived Stem cell Protein Extract (AAPE), has excellent skin regenerative properties. In this study, a human primary skin cell was devised to examine how AAPE affects human dermal fibroblast (HDF) and human keratinocyte (HK), which both play fundamental roles in skin regeneration. The promotion of collagen formation by HDFs was observed at 0.32 mg/ml of AAPE. AAPE treatment significantly stimulated stress fiber formation. DNA gene chips demonstrated that AAPE in HKs (p<0.05) affected the expression of 133 identifiable transcripts, which were associated with cell proliferation, migration, cell adhesion, and response to wounding. Twenty five identified proteins, including MMP, growth factor and cytokines such as CD54, FGF-2, GM-CSF, IL-4, IL-6, VEGF, TGF-${\beta}2$, TGF-${\beta}3$, MMP-1, MMP-10, and MMP-19, were contained in AAPE via antibody arrays. Thus, AAPE might activate the HK biological function and induce the collagen synthesis of HDF. These results demonstrate that AAPE has the potential to be used for clinic applications aimed at skin regeneration.

• Korean Journal of Materials Research
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• v.10 no.3
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• pp.218-222
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• 2000

W-Ti film properties for X-ray absorber applications have been investigated with Ti composition have been investigated with Ti composition variation. W-Ti films were deposited by DC magnetron sputtering system. As the working pressure increases, film density decreases and film stress changes from compressive to tensile. The transition pressure (where the film stress in zero) and the stress gradient decrease by adding Ti into W-Ti(6.5 at.%) film shows the smallest stress gradient and transition pressure. It also shows high density ($17.7g/\textrm{cm}^3$) similar to that of pure-W ($17.8g/\textrm{cm}^3$) at the transition pressure. All the films show columnar structure, and its size decreases with increasing Ti composition. Surface roughness and thermal stability are improved by Ti-addition, resulting in a better property for X-ray absorber applications.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.1
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• pp.63-68
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• 2013

To see if slaked lime and organic fertilizer applications to soil are useful as countermeasures for reducing $^{99}Tc$ concentrations in rice seeds after $^{99}Tc$ contamination of paddy fields, pot experiments were performed for two different paddy soils in a greenhouse. The upper soils for a depth of about 20 cm were treated with the agricultural materials and $^{99}Tc$ 15 d before transplanting. The effects were compared using the transfer factor (TF) defined as the ratio of the plant concentration to the soil concentration. In the case of control plants, TF values for brown rice in the two soils were $4.1{\times}10^{-4}$ and $4.3{\times}10^{-4}$. Of various types of the application, only the application of slaked lime at a lower dose (about 0.6 kg $m^{-2}$), which led to a 60% reduction in the TF value for one soil, seemed to be worth using as a countermeasure. Little effect of the same application was found in the other soil so it is important to determine the effect averaged for a number of soils. Organic fertilizer applications at both of two different doses increased the TF value. It is considered necessary to perform experiments for slake lime applications at doses lower than the above.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.371-374
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• 2007

A method for metal nano powder imprinting is proposed as a patterning process for conductive tracks that is inexpensive and scalable down to the nanoscale. Conductive tracks with line widths of $0.5{\sim}20{\mu}m$ were fabricated using this method. The processing conditions were optimized to avoid various types of defects, and to increase the degree of sintering and electric conductivity of the imprinted conductive tracks. The mean electric resistivity of the conductive tracks imprinted under optimum conditions was $8.95{\mu}{\Omega}{\cdot}cm$, which is in the range required for practical applications.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.123.2-123.2
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• 2016

Mg alloys have been developed for automobile and mobile equipments because of their low density of $1.7g/cm^3$. One of the main problems of Mg alloys is their poor corrosion resistance which has limited their wide applications. Plasma electrolytic oxidation (PEO) method is one of the promising surface treatment methods for Mg alloys. In this presentation, experimental data about the effects of solution composition and form of current are presented and discussed in view of dielectric breakdown and reformation of PEO films The role of various anions of phosphate, silicate, fluoride, carbonate and hydroxide ions is discussed in view of film breakdown and reformation of PEO films.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1998.06a
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• pp.145-148
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• 1998

Fluoride({{{{ { CaF}_{2 } }}}}) films exhibited a cubic structure with similar lattice constant to that of Si and have sufficient breakdown electric field as gate dielectric material. Therefore, {{{{ { CaF}_{2 } }}}} are expected to replace conventional insulator such {{{{ { SiO}_{ 2},{Ta}_{2}{O}_{ 2} and{Al}_{2}{O}_{5}. However, {CaF}_{2}}}}} films showed hystereisis properties due to mobile charges in the film. To solve this problem we performed thermal treatment and achieves field. C-v results indicate a reduced hystereisis window of {{{{ }}}}ΔV =0.2v, LOW INTERFACE STATE {{{{{D}_{it}=2.0 TIMES {10}^{11}{cm}^{-1}{eV}^{-1}}}}} in midgap, and good WIS diode properties. We observed a preferential crystallization of(200) plane from XRD analysis. RTA treatment effects on various material properties of {{{{{CaF}_{2}}}}} are presented in this paper.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.168-172
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• 2008

A microbial fuel cell is a noble green technology generating electricity from biomass and is expected to find applications in a real world. One of main hurdles to this purpose is the low power density. In this study, we constructed a prototype microbial fuel cell using Proteus vulgaris to study the effect of various reaction conditions on the performance. Main focus has been made on the modification of the anode with electropolymerized polypyrrole (Ppy). A dramatic power enhancement was resulted from the Ppy deposition onto the reticulated vitreous carbon (RVC) electrode. Our obtained maximum power density of 1.2 mW cm-3 is the highest value among the reported ones for the similar system. Further power enhancement was possible by increasing the ionic strength of the solution to decrease internal resistance of the cell. Other variables such as the deposition time, kinds of mediators, and amount of bacteria have also been examined.