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Search Results: 1 - 10 of 44011 matches for " Yong Chang Seo "
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Perspective Projection Algorithm Enabling Mobile Device’s Indoor Positioning  [PDF]
Seo Woo Han, Yun Jung Lee, Ji Hyeok Yun, Chang Yong Han, Dae Ho Lee, Doug Young Suh
Journal of Computer and Communications (JCC) , 2018, DOI: 10.4236/jcc.2018.61017
Abstract:
In order to improve the user’s satisfaction with the augmented reality (AR) technology and the accuracy of the service, it is important to obtain the exact position of the user. Frequently used techniques for finding outdoors locations is the global positioning system (GPS), which is less accurate indoors. Therefore, an indoor position is measured by comparing the reception level about access point (AP) signal of wireless fidelity (Wi-Fi) or using bluetooth low energy (BLE) tags. However, Wi-Fi and Bluetooth require additional hardware installation. In this paper, the proposed method of estimating the user’s position uses an indoor image and indoor coordinate map without additional hardware installation. The indoor image has several feature points extracted from fixed objects. By matching the feature points with the feature points of the user image, we can obtain the position of the user on the Indoor map by obtaining six or more pixel coordinates from the user image and solving the solution using the perspective projection formula. The experimental results show that the user position can be obtained more accurately in the indoor environment by using only the software without additional hardware installation.
Quantitative Estimation of Scattering Waves in Cylinder-Body Model for Body Area Networks: Comparison of Analyses with Unifrom Cylinder- and Slab-Body Models
Chang-Yong Seo;Kazuyuki Saito;Masaharu Takahashi;Koichi Ito
PIER B , 2010, DOI: 10.2528/PIERB10042801
Abstract: This paper estimates separately the components of scattering waves generated in cylinder-body model for body area networks. For the evaluation, scattering field formulations in relation to uniform cylinder- and slab-body models are provided, and the reliability of the analyses is testified by the comparison with results computed by the finite-difference time-domain (FDTD) method. Creeping waves, cylinder leaky waves, and cylinder guided waves, which are created only in cylindrical structure, are extracted quantitatively by contrasting the scattering waves that are calculated with the two body models. In addition to the extracted waves, other components of scattering waves such as reflected waves, transmitted waves, surface waves, leaky waves, and guided waves also are examined. From evaluations with various operating frequencies and thicknesses of the body model, it is confirmed that reflected waves have the most influence on electrical characteristics of a source. Moreover creeping waves and cylinder leaky waves are generally dominant at the opposite side of the cylinder when a source is located near cylinder surface. Furthermore, the existence of creeping waves with low attenuation in the vicinity of cylinder surface is demonstrated by electric field intensities calculated by varying the observation point along cylinder axis.
Stretchable Strain Sensors Fabricated by Screen Printing of Silver Paste on the Surface Modified Transparent Elastomeric Polyurethane Films  [PDF]
Chang Gyu Lee, Bo Seok Kwon, Hyun Min Nam, Duck Min Seo, Jinwoo Park, Hyuc Hwangbo, Lee Soon Park, Su Yong Nam
Materials Sciences and Applications (MSA) , 2018, DOI: 10.4236/msa.2018.913073
Abstract: Strain sensors for human-motion detection must offer high stretchability, high sensitivity, fast response, and high recovery speed. In this study, we choose silver paste as a sensing material and use a screen printing method to fabricate the strain sensor based upon an electrical-resistance mechanism. After curing elastomeric polyurethane film with a thickness of 150 μm on PET film, the polyester resin mixed with blocked isocyanate curing agent was coated as a masking layer to reduce the film’s stickiness. The effect of the polyester masking layer upon the silver paste screen printing process was examined using a rolling-ball-tack test, TGA analysis of polyester resins, and cured silver-electrode films. The cost-effective strain sensor fabricated by using silver paste and screen printing processes on the stretchable-polyurethane-substrate film showed high sensitivity and fast response in a strain range of up to 100%.
Effect of Nanoencapsulated Vitamin B1 Derivative on Inhibition of Both Mycelial Growth and Spore Germination of Fusarium oxysporum f. sp. raphani
Jeong Sub Cho,Yong Chang Seo,Tae Bin Yim,Hyeon Yong Lee
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14024283
Abstract: Nanoencapsulation of thiamine dilauryl sulfate (TDS), a vitamin B1 derivative, was proved to effectively inhibit the spore germination of Fusarium oxysporum f. sp. raphani ( F . oxysporum), as well as mycelial growth. The average diameter of nanoparticles was measured as 136 nm by being encapsulated with an edible encapsulant, lecithin, whose encapsulation efficiency was about 55% in containing 200 ppm of TDS concentration: the 100 ppm TDS nanoparticle solution showed a mycelial growth inhibition rate of 59%. These results were about similar or even better than the cases of treating 100 ppm of dazomet, a positive antifungal control (64%). Moreover, kinetic analysis of inhibiting spore germination were estimated as 6.6% reduction of spore germination rates after 24 h treatment, which were 3.3% similar to the case of treating 100 ppm of a positive control (dazomet) for the same treatment time. It was also found that TDS itself could work as an antifungal agent by inhibiting both mycelial growth and spore germination, even though its efficacy was lower than those of nanoparticles. Nanoparticles especially played a more efficient role in limiting the spore germination, due to their easy penetration into hard cell membranes and long resident time on the surface of the spore shell walls. In this work, it was first demonstrated that the nanoparticle of TDS not a harmful chemical can control the growth of F . oxysporum by using a lower dosage than commercial herbicides, as well as the inhibiting mechanism of the TDS. However, field trials of the TDS nanoparticles encapsulated with lecithin should be further studied to be effectively used for field applications.
Statistical Properties of Galactic δ Scuti Stars: Revisited
Seo-Won Chang,Pavlos Protopapas,Dae-Won Kim,Yong-Ik Byun
Physics , 2013, DOI: 10.1088/0004-6256/145/5/132
Abstract: We present statistical characteristics of 1,578 {\delta} Scuti stars including nearby field stars and cluster member stars within the Milky Way. We obtained 46% of these stars (718 stars) from the works done by Rodr\'{i}guez and collected the remaining 54% stars (860 stars) from other literatures. We updated the entries with the latest information of sky coordinate, color, rotational velocity, spectral type, period, amplitude and binarity. The majority of our sample are well characterized in terms of typical period range (0.02-0.25 days), pulsation amplitudes (<0.5 mag) and spectral types (A-F type). Given this list of {\delta} Scuti stars, we examined relations between their physical properties (i.e., periods, amplitudes, spectral types and rotational velocities) for field stars and cluster members, and confirmed that the correlations of properties are not significantly different from those reported in the Rodr\'{i}guez's works. All the {\delta} Scuti stars are cross-matched with several X-ray and UV catalogs, resulting in 27 X-ray and 41 UV-only counterparts. These counterparts are interesting targets for further study because of their rarity and uniqueness in showing {\delta} Scuti-type variability and X-ray/UV emission at the same time. The compiled catalog can be accessed through the web interface http://stardb.yonsei.ac.kr/DeltaScuti
Stable Isolation of Phycocyanin from Spirulina platensis Associated with High-Pressure Extraction Process
Yong Chang Seo,Woo Seok Choi,Jong Ho Park,Jin Oh Park,Kyung-Hwan Jung,Hyeon Yong Lee
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14011778
Abstract: A method for stably purifying a functional dye, phycocyanin from Spirulina platensis was developed by a hexane extraction process combined with high pressure. This was necessary because this dye is known to be very unstable during normal extraction processes. The purification yield of this method was estimated as 10.2%, whose value is 3%–5% higher than is the case from another conventional separation method using phosphate buffer. The isolated phycocyanin from this process also showed the highest purity of 0.909 based on absorbance of 2.104 at 280 nm and 1.912 at 620 nm. Two subunits of phycocyanin namely α-phycocyanin (18.4 kDa) and β-phycocyanin (21.3 kDa) were found to remain from the original mixtures after being extracted, based on SDS-PAGE analysis, clearly demonstrating that this process can stably extract phycocyanin and is not affected by extraction solvent, temperature, etc. The stability of the extracted phycocyanin was also confirmed by comparing its DPPH (α,α-diphenyl-β-picrylhydrazyl) scavenging activity, showing 83% removal of oxygen free radicals. This activity was about 15% higher than that of commercially available standard phycocyanin, which implies that the combined extraction method can yield relatively intact chromoprotein through absence of degradation. The results were achieved because the low temperature and high pressure extraction effectively disrupted the cell membrane of Spirulina platensis and degraded less the polypeptide subunits of phycocyanin (which is a temperature/pH-sensitive chromoprotein) as well as increasing the extraction yield.
Enhanced Immunomodulatory Activity of Gelatin-Encapsulated Rubus coreanus Miquel Nanoparticles
Yong Chang Seo,Woon Yong Choi,Choon Geun Lee,Seon Woo Cha,Young Ock Kim,Jin-Chul Kim,Gregor P. C. Drummen,Hyeon Yong Lee
International Journal of Molecular Sciences , 2011, DOI: 10.3390/ijms12129031
Abstract: The aim of this work was to investigate the immunomodulatory activities of Rubus coreanus Miquel extract-loaded gelatin nanoparticles. The mean size of the produced nanoparticles was 143 ± 18 nm with a bandwidth of 76 nm in the size distribution and a maximum size of ~200 nm, which allows effective nanoparticle uptake by cells. Confocal imaging confirmed this, since the nanoparticles were internalized within 30 min and heterogeneously distributed throughout the cell. Zeta-potential measurements showed that from pH = 5 onwards, the nanoparticles were highly negatively charged, which prevents agglomeration to clusters by electrostatic repulsion. This was confirmed by TEM imaging, which showed a well dispersed colloidal solution. The encapsulation efficiency was nearly 60%, which is higher than for other components encapsulated in gelatin nanoparticles. Measurements of immune modulation in immune cells showed a significant effect by the crude extract, which was only topped by the nanoparticles containing the extract. Proliferation of B-, T- and NK cells was notably enhanced by Rubus coreanus-gelatin nanoparticles and in general ~2–3 times higher than control and on average ~2 times higher than ferulic acid. R. coreanus-gelatin nanoparticles induced cytokine secretion (IL-6 and TNF-α) from B- and T-cells on average at a ~2–3 times higher rate compared with the extract and ferulic acid. I n vivo immunomodulatory activity in mice fed with R. coreanus-gelatin nanoparticles at 1 mL/g body weight showed a ~5 times higher antibody production compared to control, a ~1.3 times higher production compared to the extract only, and a ~1.6 times higher production compared to ferulic acid. Overall, our results suggest that gelatin nanoparticles represent an excellent transport vehicle for Rubus coreanus extract and extracts from other plants generally used in traditional Asian medicine. Such nanoparticles ensure a high local concentration that results in enhancement of immune cell activities, including proliferation, cytokine secretion, and antibody production.
Detecting Variability in Massive Astronomical Time-Series Data II: Variable Candidates in the Northern Sky Variability Survey
Min-Su Shin,Hahn Yi,Dae-Won Kim,Seo-Won Chang,Yong-Ik Byun
Physics , 2011, DOI: 10.1088/0004-6256/143/3/65
Abstract: We present variability analysis of data from the Northern Sky Variability Survey (NSVS). Using the clustering method which defines variable candidates as outliers from large clusters, we cluster 16,189,040 light curves, having data points at more than 15 epochs, as variable and non-variable candidates in 638 NSVS fields. Variable candidates are selected depending on how strongly they are separated from the largest cluster and how rarely they are grouped together in eight dimensional space spanned by variability indices. All NSVS light curves are also cross-correlated to the Infrared Astronomical Satellite, AKARI, Two Micron All Sky Survey, Sloan Digital Sky Survey (SDSS), and Galaxy Evolution Explorer objects as well as known objects in the SIMBAD database. The variability analysis and cross-correlation results are provided in a public online database which can be used to select interesting objects for further investigation. Adopting conservative selection criteria for variable candidates, we find about 1.8 million light curves as possible variable candidates in the NSVS data, corresponding to about 10% of our entire NSVS samples. Multi-wavelength colors help us find specific types of variability among the variable candidates. Moreover, we also use morphological classification from other surveys such as SDSS to suppress spurious cases caused by blending objects or extended sources due to the low angular resolution of the NSVS.
Interpretable Housing for Freedom of the Body: The Next Generation of Flexible Homes  [PDF]
Kyung Wook Seo, Chang Sung Kim
Journal of Building Construction and Planning Research (JBCPR) , 2013, DOI: 10.4236/jbcpr.2013.13011
Abstract: If we have gone through the first generation of housing design that pursued functional optimization, ergonomics, and circulation efficiency during the last century, now we are living in the second generation where more advanced goals, such as universal design, ubiquitous design, sustainable design, and environment-friendly design, are emphasized. Although this second generation of design focuses upon the wellness of humans in accordance with environment, it still has the attitude that a more precisely designed home can guarantee a better life. What lacks in this approach is the freedom of the body; it needs to make its own choice as to how to use a space. Thus, it is suggested in this paper that what is important in designing a home is to provide alternatives in daily lives so as to make a full exploration of a given space. These alternatives can be made by offering residents an interpretable space where they can figure out space usages and routs in a constantly changing context. Two spatial devices are discussed in depths as a way to realize this interpretable house: room-to-room enfilade and ring spatial structure. By investigating some existing house plans, it is illustrated how they can guarantee the freedom of the body, and thus alternatives for the flexible domestic life.
The Architectural Expression of Space and Form Created by the Light in the Works of Alvaro Siza  [PDF]
Chang Sung Kim, Kyung Wook Seo
Journal of Building Construction and Planning Research (JBCPR) , 2014, DOI: 10.4236/jbcpr.2014.22011
Abstract: The light is an important element which helps people perceive objects. Therefore, it is important for architects to make the light and space be in harmony with each other. In this study, we analyzed the works of Alvaro Siza with a view to understand the conceptual value of the light expressed in his works and his principles in controlling it. According to the results of the study, the Siza’s architecture is not a mere theoretical one trapped inside formality, but is a sensual and experiential one based on the locality. He was willing to use void spaces to invite the light in free-flowing plans, in order to invigorate and extend architectural spatiality to create deeper visual effect. In addition, the refined light in his works helped visitors experience the continuous forms and spaces by their own movements, while using the changes of the light to stimulate the interest of visitors and highlight the sequence of spaces.
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