• Journal of KIISE:Software and Applications
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• v.34 no.10
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• pp.889-899
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• 2007

In proteomics, recent advancements In mass spectrometry technology and in protein extraction and separation technology made high-throughput analysis possible. This leads to thousands to hundreds of thousands of MS/MS spectra per single LC-MS/MS experiment. Such a large amount of data creates significant computational challenges and therefore effective data analysis methods that make efficient use of computational resources and, at the same time, provide more peptide identifications are in great need. Here, SIFTER system is designed to avoid inefficient processing of shotgun proteomic data. SIFTER provides software tools that can improve throughput of mass spectrometry-based peptide identification by filtering out poor-quality tandem mass spectra and estimating a Peptide charge state prior to applying analysis algorithms. SIFTER tools characterize and assess spectral features and thus significantly reduce the computation time and false positive rates by localizing spectra that lead to wrong identification prior to full-blown analysis. SIFTER enables fast and in-depth interpretation of tandem mass spectra.

• Tunnel and Underground Space
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• v.16 no.5 s.64
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• pp.387-393
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• 2006

This paper introduces the combination of two blasting methods applied to reduce blast-vibration and increase blast efficiency. NDC (New Deck Charge) blasting method using air deck effect with separation tube made of paper was effective to reduce blast-vibration, while blast efficiency was decreased a little in the bottom of a blasthole. Wide Space blasting method has an advantage to control the fragmentation and to increase blast efficiency over conventional blasting methods. In this study new blasting method combining NDC blasting method and Wide Space blasting method was applied to the field, it was confirmed to reduce blast-vibration and increase blast efficiency. It is expected to make useful blasting method to cover the public complaints and to shorten construction time by accumulating blasting data using new method with various conditions.

• Journal of Radiation Protection and Research
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• v.44 no.2
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• pp.53-63
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• 2019

Background: As neutron fields are always accompanied by gamma rays, it is essential to distinguish neutrons from gamma rays in the detection of neutrons. Neutrons and gamma rays can be separated by pulse shape discrimination (PSD) methods. Recently, we performed characterization of a stilbene scintillator detector and an EJ-301 liquid scintillator detector with a high-speed digitizer DT5730 and investigated optimized PSD variables for both detectors. This study is for providing a basis for developing fast neutron/gamma-ray dual-particle imager. Materials and Methods: We conducted PSD experiments using stilbene scintillator and EJ-301 liquid scintillator and evaluated neutron and gamma ray discriminability of each PSD method with a $^{137}Cs$ gamma source and a $^{252}Cf$ neutron source. We implemented digital signal processing techniques to apply two PSD methods - the charge comparison (CC) method and the constant time discrimination (CTD) method - to distinguish neutrons from gamma rays. We tried to find optimized PSD variables giving the best discriminability in a given experimental condition. Results and Discussion: For the stilbene scintillator detector, the charge comparison method and the constant time discrimination method both delivered the PSD FOM values of 1.7. For the EJ-301 liquid scintillator detector, both PSD methods delivered the PSD FOM values of 1.79. With the same PSD variables, PSD performance was excellent in $300{\pm}100keVee$, $500{\pm}100keVee$, and $700{\pm}100keVee$ energy regions. This result shows that we can achieve an effective discrimination of neutrons from gamma rays using these scintillator detector systems. Conclusion: We applied both PSD methods to a stilbene and a liquid scintillator and optimized the PSD performance represented by FOM values. We observed a good separation performance of both scintillators combined with a high-speed digitizer and digital PSD. These results will provide reference values for the dual-particle imager we are developing, which can image both fast neutrons and gamma rays simultaneously.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3671-3676
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• 2013

A series of carbon nanotube, $C_{60}$, and graphene modified $TiO_2$ nanocomposites were prepared by hydrothermal method. X-ray diffraction, $N_2$ adsorption, UV-Vis spectroscopy, photoluminescence, and Electrochemical impedance spectra were used to characterize the prepared composite materials The results reveal that incorporating $TiO_2$ with carbon materials can extend the adsorption edge of all the $TiO_2$-carbon nanocomposites to the visible light region. The photocatalytic activities were tested in the degradation of 2,4,6-trichlorophenol (TCP) under visible light. No obvious difference in essence was observed in structural and optical properties among three series of carbon modified $TiO_2$ nanocomposites. Three series of carbon materials modified $TiO_2$ composites follow the analogous tentative reaction mechanism for TCP degradation. GR modified $TiO_2$ nanocomposite exhibits the strongest interaction and the most effective interfacial charge transfer among three carbon materials, thus shows the highest electron-hole separation rate, leading to the highest photocatalytic activity and stability.

• Rapid Communication in Photoscience
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• v.3 no.2
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• pp.35-37
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• 2014

PEC (photoelectrochemical) water splitting for $O_2/H_2$ production is one of the promising but difficult way to utilize solar energy. Among photocatalytic materials for PEC water oxidation, $BiVO_4$ (Eg = 2.4 eV) has been recently intensively studied since it has various advantageous properties. But its maximum efficiency has not been realized owing to kinetic factors - slow water oxidation at surface & insufficient stability. These problems can be simultaneously solved by application of oxygen evolution catalyst (OEC) such as $CoO_x$, Co-Pi, $IrO_x$ etc. Herein we report the first successful application of $NiFeO_x$ OEC on $BiVO_4$, showing good performance compared to other effective OEC applied on $BiVO_4$ under basic conditions. The enhanced activity of OEC loaded $BiVO_4$ has been supported by the surface charge separation efficiency and electrochemical impedance studies.

• Korean Chemical Engineering Research
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• v.57 no.2
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• pp.259-266
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• 2019

Tuning of electro-optical properties of nano-structured $SnO_2:Ga$ powders in a micro drop fluidized reactor (MDFR) was highly effective to enhance the activities of powders to be used as sensor materials. The tuning was conducted continuously in a facile one-step process during the formation of powders. The microscopic hydrodynamic forces affected the band gap structure and charge transfer of $SnO_2:Ga$ powders through the oxygen and interfacial tin vacancies by providing plausible pyro-hydraulic conditions, which resulted in the decrease in the electrical resistance of the materials. The analyses of room-temperature photoluminescence (PL) spectra and FT-IR exhibited that the tuning could improve the surface activities of $SnO_2:Ga$ powders by adjusting the excitation as well as separation of electrons and holes, thus maximizing the oxygen vacancies at the surface of the powders. The scheme of photocatalytic mechanism of $SnO_2:Ga$ powders was also discussed.

• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.547-553
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• 2017

This study focused on the difference of photocatalytic performance by the incorporation of Pd into the $TiO_2$ framework and suggested five different catalysts composed of $TiO_2$ and x mol% $Pd-TiO_2$ (x = 0.25, 0.5, 0.75, and 1.0). A typical sol-gel method was used to synthesize catalysts, and the phenol photodegradation performance of each catalysts was evaluated. The physicochemical and optical properties of catalysts were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy/energy dispersive spectrometer (SEM/EDS), ultraviolet/visible spectroscopy (UV/Vis), photoluminescence spectroscopy (PL), and photocurrent measurements. With the addition of Pd ions, the band gap of catalysts was shortened and the charge separation between photogenerated electrons and holes easily also occurred. As a result, the phenol photo-destruction performance over 0.75 mol% $Pd-TiO_2$ catalyst was 3 times higher than that of pure $TiO_2$. This is believed to be due to Pd ions acted as an electron capturing function during photocatalysis.

• Korean Journal of Materials Research
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• v.28 no.4
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• pp.214-220
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• 2018

We report on the fabrication and photoelectrochemical(PEC) properties of a $Cu_2O$ thin film/ZnO nanorod array oxide p-n heterojunction structure with ZnO nanorods embedded in $Cu_2O$ thin film as an efficient photoelectrode for solar-driven water splitting. A vertically oriented n-type ZnO nanorod array was first prepared on an indium-tin-oxide-coated glass substrate via a seed-mediated hydrothermal synthesis method and then a p-type $Cu_2O$ thin film was directly electrodeposited onto the vertically oriented ZnO nanorods array to form an oxide semiconductor heterostructure. The crystalline phases and morphologies of the heterojunction materials were characterized using X-ray diffraction and scanning electron microscopy as well as Raman scattering. The PEC properties of the fabricated $Cu_2O/ZnO$ p-n heterojunction photoelectrode were evaluated by photocurrent conversion efficiency measurements under white light illumination. From the observed PEC current density versus voltage (J-V) behavior, the $Cu_2O/ZnO$ photoelectrode was found to exhibit a negligible dark current and high photocurrent density, e.g., $0.77mA/cm^2$ at 0.5 V vs $Hg/HgCl_2$ in a $1mM\;Na_2SO_4$ electrolyte, revealing an effective operation of the oxide heterostructure. In particular, a significant PEC performance was observed even at an applied bias of 0 V vs $Hg/HgCl_2$, which made the device self-powered. The observed PEC performance was attributed to some synergistic effect of the p-n bilayer heterostructure on the formation of a built-in potential, including the light absorption and separation processes of photoinduced charge carriers.

• Journal of the Korean Applied Science and Technology
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• v.30 no.1
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• pp.49-56
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• 2013

Excellent electron transport properties with enhanced light scattering ability for light harvesting have made well-ordered one dimensional $TiO_2$ nanotube(TNT) arrays an alternative candidate over $TiO_2$ nanoparticles in the area of solar energy conversion applications. The principal drawback of TNT arrays being activated only by UV light has been addressed by coupling the TNT with secondary materials which are visible light-triggered. As well as extending the absorption region of sunlight, the introduction of these foreign components is also found to influence the charge separation and electron lifetime of TNT. In this study, a novel method to fabricate the TNT-based composite photoelectrodes employing visible responsive $CuInS_2$ (CIS) nanoparticles is presented. The developed method is a square wave pulse-assisted electrochemical deposition approach to wrap the inner and outer walls of a TNT array with CIS nanoparticles. Instead of coating as a dense compact layer of CIS by a conventional non-pulsed-electrochemical deposition method, the nanoparticles pack relatively loosely to form a rough surface which increases the surface area of the composite and results in a higher degree of light scattering within the tubular channels and hence a greater chance of absorption. The excellence coverage of CIS on the tubular $TiO_2$ allows the construction of an effective heterojunction that exhibits enhanced photoelectrochemical performance.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.631-631
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• 2013

Battery has major drawbacks including its size and life expectancy, and environmental problem. As an alternative, energy harvesting is emerging as a potential solution to replace battery along with more energy-efficient IT devices. The idea of harnessing energy from our living environment is sustainable, semi-permanent, and eco-friendly. Also, unlike battery, energy harvester does not require much space to store energy. Therefore, energy harvesting can provide a better source of power for small, portable, and wireless devices. Among various ways of harvesting energy from our surroundings, triboelectricity is chosen due to its potential to be miniaturized, and efficient. Triboelectric effect occurs as two different materials with different polarity of charge separation come into contact through friction, and then become separated so that electric potential difference is achieved. In this research, such characteristic of triboelectricity is used as a way to convert ambient mechanical energy into electric energy.Series of recent researches have shown promising results that the triboelectric energy harvester can be simple and cost effective. However, sufficient electricity level required to operate mobile devices has not yet been achieved.In this research, our group focuses on the design and optimization of triboelectric energy harvesting device to enhance its output. By using maskless lithography to pattern Kapton film and silicon substrate, which is used as a mold for PDMS thin layer, and sputtering metal electrodes on each side, we fabricate and demonstrate different designs of triboelectric energy harvester that utilizes the contact electrification between a polymer thin film and a metal thin foil. In order to achieve optimized result, the output voltage and current are measured under diverse conditions, which include different surface structure and pattern, material, and the gap between layers.