• Korean Journal of Materials Research
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• v.21 no.10
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• pp.546-549
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• 2011

Nano-sized $SnO_2$ thick films were prepared by a screen-printing method onto $Al_2O_3$ substrates. The sensing characteristics were investigated by measuring the electrical resistance of each sensor in a test box as a function of the detection gas. The nano-sized $SnO_2$ thick film sensors were treated in a $N_2$ atmosphere. The structural properties of the nano $SnO_2$with a rutile structure according to XRD showed a (110) dominant $SnO_2$ peak. The particle size of $SnO_2$:Ni nano powders at Ni 8 wt% was about 45 nm, and the $SnO_2$ particles were found to contain many pores according to the SEM analysis. The sensitivity of the nano $SnO_2$-based sensors was measured for 5 ppm $CH_4$ gas and $CH_3CH_2CH_3$ gas at room temperature by comparing the resistance in air with that in the target gases. The results showed that the best sensitivity of $SnO_2$:Ni and $SnO_2$:Co sensors for $CH_4$ gas and $CH_3CH_2CH_3$ gas at room temperature was observed in $SnO_2$:Ni sensors doped with 8 wt% Ni. The response time of the $SnO_2$:Ni gas sensors was 10 seconds and recovery time was 15 seconds for the $CH_4$ and $CH_3CH_2CH_3$ gases.

• Macromolecular Research
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• v.16 no.8
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• pp.695-703
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• 2008

Nanoparticles have tremendous potential in cancer prevention, detection and augmenting existing treatments. They can target tumors, carry imaging capability to document the presence of tumors, sense pathophysiological defects in tumor cells, deliver therapeutic genes or drugs based on the tumor characteristics, respond to external triggers to release an appropriate agent, document the tumor response, and identify the residual tumor cells. Nanoparticles < 30 nanometers in diameter show unexpected and unique properties. Furthermore, particles < 5 nanometers in size can easily penetrate cells as well as living tissues and organs. This study evaluated the safety of nano materials in a living body and the relationship between the living tissue and synthetic nano materials by examining the in-vitro cytotoxicity of poly(lactic-co-glycolic) acid (PLGA) nano-spheres and fluorescein isothiocynate(FITC)-labeled dendrimers as polymer nanoparticles. PLGA was chosen because it has been used extensively for biodegradable nanoparticles on account of its outstanding bio-compatibility and its acceptance as an FDA approved material. The dendrimer was chosen because it can carry a molecule that recognizes cancer cells, a therapeutic agent that can kill those cells, and a molecule that recognizes the signals of cell death. Cytotoxicity in L929 mouse fibroblasts was monitored using MTT assay. Microscopic observations were also carried out to observe cell growth. All assays yielded meaningful results and the PLGA nanoparticles showed less cytotoxicity than the dendrimer. These nano-particles ranged in size from 10 to 100 nm according to microscopy and spectroscopic methods.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3665-3670
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• 2012

Metal-p-$NH_2$-Bn-DOTA (paraammionobenzyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid: ABDOTA) complex was synthesized and purified for bio-tagging to quantify biological target materials using laser ablation (LA)-ICP-MS. Since the preparation of a pure and stable tagging complex is the key procedure for quantification, magnetic particles were used to purify the synthesized metal-ABDOTA complex. The magnetic particles immobilized with the complex attracted to a permanent magnet, resulting in fast separation from free un-reacted metal ions in solution. Gd ions formed the metal-complex with a higher yield of 64.3% (${\pm}3.9%$ relative standard deviation (RSD)) than Y ions, 52.3% (${\pm}2.5%$ RSD), in the pH range 4-7. The complex bound to the magnetic particles was released by treatment with a strong base, of which the recovery was 81.7%. As a reference, a solid phase extraction (SPE) column packed with Chelex-100 resin was employed for separation under similar conditions and produced comparable results. The tagging technique complemented polydimethylsiloxane (PDMS) microarray chip sampling in LA-ICP-MS, allowing determination of small sample volumes at high throughputs. For application, immunoglobulin G (IgG) was immobilized on the pillars of PDMS microarray chips and then tagged with the prepared Gd complex. IgG could then be determined through measurement of Gd by LA-ICP-MS. A detection limit of 1.61 ng/mL (${\pm}0.75%$ RSD) for Gd was obtained.

• Advances in materials Research
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• v.3 no.3
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• pp.139-149
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• 2014

Surface enhanced Raman Scattering (SERS) has attracted attention because the technique enables detection of various chemicals, even down to single molecular scale. Among the diverse candidates for SERS substrates, Au nanoparticles are considered promising due to their fine optical properties, chemical stability and ease of surface modification. Therefore, the fabrication and optical characterization of gold particles on solid supports is highly desirable. Such structures have potential as SERS substrates because the localized surface plasmon resonance of gold nanoparticles is very sensitive to combined molecules and environments. In addition, it is well-known that the properties of Au nanoparticles are strongly dependent on their shape. In this work, arrays of shape-controlled Au nanoparticles were fabricated to exploit their enhanced and reproducible optical properties. First, shape-controlled Au nanoparticles were prepared via seed mediated solution-phase synthesis, including spheres, octahedra, and rhombic dodecahedra. Then, these shape-controlled Au nanoparticles were arranged on a PDMS substrate, which was nanopatterned using soft lithography of poly styrene particles. The Au nanoparticles were selectively located in a pattern of hexagonal spheres. In addition, the shape-controlled Au nanoparticles were arranged in various sizes of PDMS nanopatterns, which can be easily controlled by manipulating the size of polystyrene particles. Finally, the optical properties of the fabricated Au nanoparticle arrays were characterized by measuring surface enhanced Raman spectra with 4-nitrobenezenethiol.

• Journal of Radiation Protection and Research
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• v.18 no.2
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• pp.17-25
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• 1993

Beta ray spectra of $^3H,\;^{14}C\;and\;^{36}Cl$ in liquid scintillation counting system have been calculated using the Monte Carlo method by which physical behaviors of particle transport in medium were simulated. The calculations have been carried out on the basis of beta rays being slowing down according to the continuous slowing down approximation(CSDA) model. Beta rays generated in simulation geometry were traced until they lost their energy below 0.3keV that in known to be the detection limit in the liquid scintillation counter. Scintillator solution in which pure beta emitting radionuclides were dissolved uniformly was assumed to be bottled in the shape of right circular cylinder with 12.5mm in radius and 35mm in height. The comparison of the calculated and measured results showed satisfactory agreement between those two, with slight discrepancy due to self quenching in the case of lower energy of emitted beta particles in the solution.

• Korean Journal of Remote Sensing
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• v.30 no.5
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• pp.559-570
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• 2014

Backscatter signal observed from the space-borne Light Detection And Ranging (LIDAR) system is providing unique 3-dimensional spatial distribution as well as temporal variations for atmospheric aerosols. In this study, the continuous observations for aerosol profiles were analyzed during a years of 2012 by using a Cloud-Aerosol LIDAR with Orthogonal Polarization (CALIOP), carried on the Cloud-Aerosol LIDAR and Infrared Pathfinder Satellite Observation (CALIPSO) satellite. The statistical analysis on the particulate extinction coefficient and depolarization ratio for each altitude was conducted according to time and space in order to estimate the variation of optical properties of aerosols over Northeast Asia ($E110^{\circ}-140^{\circ}$, $N20^{\circ}$ $-50^{\circ}$). The most frequent altitudes of aerosols are clearly identified and seasonal mean aerosol profiles vary with season. Since relatively high particle depolarization ratios (>0.5) are found during all seasons, it is considered that the non-spherical aerosols mixed with pollution are mainly exists over study area. This study forms initial regional 3-dimensional aerosol information, which will be extended and improved over time for estimation of aerosol climatology and event cases.

• Analytical Science and Technology
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• v.34 no.5
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• pp.212-224
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• 2021

The intent of the present work was to develop a simple, sensitive, accurate, precise, rapid and economical UV- spectrophotometric and reverse phase high pressure liquid chromatographic method for the simultaneous estimation of Spironolactone and Furosemide in bulk and combined tablet dosage forms. UV-Spectrophotometry was carried out by simultaneous equation method using 0.02 M potassium dihydrogen phosphate buffer pH 3.5: Acetonitrile (50:50) v/v as a solvent. The linearity range was 2-14 ㎍ mL^-1 for Spironolactone and Furosemide with a correlation coefficient > 0.99. The chromatographic separation was achieved on 250 mm × 4.6 mm, hypersil BDS C18 column with particle size 5 ㎛, by using an isocratic mixture of 0.02 M potassium dihydrogen phosphate buffer pH 3.5: Acetonitrile: tert butyl methyl ether (49:50:1) v/v/v as a solvent at a flow rate of 1 mL min^-1 and UV detection was carried out at 254 nm. The retention time were observed to be 3.666 and 6.661 minutes for Furosemide and Spironolactone respectively. The two developed methods were validated according to the ICH guidelines for accuracy, precision, linearity, LOD, LOQ and were found to be within the limits. It can be concluded that these two methods could be successfully used for the simultaneous estimation of Spironolactone and Furosemide in bulk and combined tablet dosage forms.

• Toxicological Research
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• v.35 no.3
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• pp.257-270
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• 2019

Silver nanoparticles (AgNPs) have been widely used in a variety of applications in innovative development; consequently, people are more exposed to this particle. Growing concern about toxicity from AgNP exposure has attracted greater attention, while questions about nanosilver-responsive genes and consequences for human health remain unanswered. By considering early detection and prevention of nanotoxicology at the genetic level, this study aimed to identify 1) changes in gene expression levels that could be potential indicators for AgNP toxicity and 2) morphological phenotypes correlating to toxicity of HepG2 cells. To detect possible nanosilver-responsive genes in xenogenic targeted organs, a comprehensive systematic literature review of changes in gene expression in HepG2 cells after AgNP exposure and in silico method, connection up- and down-regulation expression analysis of microarrays (CU-DREAM), were performed. In addition, cells were extracted and processed for transmission electron microscopy to examine ultrastructural alterations. From the Gene Expression Omnibus (GEO) Series database, we selected genes that were up- and down-regulated in AgNPs, but not up- and down-regulated in silver ion exposed cells, as nanosilver-responsive genes. HepG2 cells in the AgNP-treated group showed distinct ultrastructural alterations. Our results suggested potential representative gene data after AgNPs exposure provide insight into assessment and prediction of toxicity from nanosilver exposure.

• Journal of Information Processing Systems
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• v.14 no.6
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• pp.1445-1456
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• 2018

Environment perception and three-dimensional (3D) reconstruction tasks are used to provide unmanned ground vehicle (UGV) with driving awareness interfaces. The speed of obstacle segmentation and surrounding terrain reconstruction crucially influences decision making in UGVs. To increase the processing speed of environment information analysis, we develop a CPU-GPU hybrid system of automatic environment perception and 3D terrain reconstruction based on the integration of multiple sensors. The system consists of three functional modules, namely, multi-sensor data collection and pre-processing, environment perception, and 3D reconstruction. To integrate individual datasets collected from different sensors, the pre-processing function registers the sensed LiDAR (light detection and ranging) point clouds, video sequences, and motion information into a global terrain model after filtering redundant and noise data according to the redundancy removal principle. In the environment perception module, the registered discrete points are clustered into ground surface and individual objects by using a ground segmentation method and a connected component labeling algorithm. The estimated ground surface and non-ground objects indicate the terrain to be traversed and obstacles in the environment, thus creating driving awareness. The 3D reconstruction module calibrates the projection matrix between the mounted LiDAR and cameras to map the local point clouds onto the captured video images. Texture meshes and color particle models are used to reconstruct the ground surface and objects of the 3D terrain model, respectively. To accelerate the proposed system, we apply the GPU parallel computation method to implement the applied computer graphics and image processing algorithms in parallel.

• Journal of IKEEE
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• v.23 no.3
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• pp.947-953
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• 2019

The purpose of this paper is to explore an ASIC design for estimating sizes and concentrations of airborne micro-particles by the means of integrating, amplifying and digitizing electric charge signals generated by photo-sensors as it receives scattered photons by the presence of micro-particles, consisting of a pre-amplifier that detects and amplifies voltage or current signal from photo-sensor that generates charges (hole-electron pairs) when exposed to visible rays, infrared rays, ultraviolet rays, etc. according to the intensity of rays; a shaper for shaping the amplified signal to a semi-gaussian waveform; two discriminators and binary counters for outputting digital signals by comparing the magnitude of the shaped signal with an arbitrary reference voltages. The ASIC with the proposed architecture and functional blocks in this study was designed with a 0.18um standard CMOS technology from Global Foundries and the operation and performances of the ASIC has been verified by the silicons fabricated by using the process.