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RISS 인기검색어
- 검색키워드
- 저자 : Daeseong Kim (검색결과 70 건)
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Kim, Yeongsik,Yong, Daeseong,Lee, Wooseop,Jo, Seongjun,Ahn, Hyungju,Kim, Jaeup U.,Ryu, Du Yeol American Chemical Society 2018 Macromolecules Vol.51 No.21
<P>We present a compelling evidence for thickness dependence on the order-to-disorder transition (ODT) behavior in cylinder- and lamella-forming polystyrene-<I>b</I>-poly(2-vinylpyridine) (PS-<I>b</I>-P2VP) films. Such an asymmetric wetting condition that confines the films with selective interactions of the PS/air and P2VP/substrate interfaces generates a parallel orientation of cylindrical and lamellar microdomains. We evaluated thickness-dependent phase transition as a function of interlattice distance (<I>L</I><SUB>0</SUB>) using <I>ex situ</I> grazing incidence small-angle X-ray scattering (GISAXS) and transmission electron microscopy (TEM). Below an onset thickness (<I>t</I><SUB>0</SUB>) above which the ODT temperatures (<I>T</I><SUB>ODT</SUB>s) of the films are independent of film thickness, the <I>T</I><SUB>ODT</SUB>s of cylinder- and lamella-forming PS-<I>b</I>-P2VP films remarkably increase as the film thickness decreases. Our results confirmed that preferential wetting at the PS/air and P2VP/substrate interfaces in very thin films substantially leads to an ordered state over accessible temperature range up to ∼260 °C. More interestingly, the <I>t</I><SUB>0</SUB> of lamellar morphology (∼22<I>L</I><SUB>0</SUB>) is thicker than that of cylindrical morphology (∼10<I>L</I><SUB>0</SUB>), indicating that the interfacial interactions are more influential to a 1D multilayer structure of lamellar microdomains than a 2D hexagonally packed order of parallel cylinders. Our theoretical calculation utilizing the self-consistent field theory (SCFT) of a discrete bead-spring model with finite-range interactions exhibited the similar thickness dependence of ODTs for cylinder- and lamella-forming PS-<I>b</I>-P2VP films confined in such an asymmetric wetting condition.</P> [FIG OMISSION]</BR>
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Development of the Titanium Dioxide Photocatalyst Coating for Asphalt Pavement
Daeseong Jang,Young Kim,Dr. SangHoon Kim,Dr. JaeJun Lee 한국도로학회 2018 한국도로학회 학술대회 발표논문 초록집 Vol.2018 No.05
This study shows the development of a photocatalytic technology for the road to decompose the nitrogen oxides(NOx) using a titanium oxide(TiO2) photocatalyst coating method for reducing the air pollution
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Oil Spill Detection from RADARSAT-2 SAR Image Using Non-Local Means Filter
Kim, Daeseong,Jung, Hyung-Sup The Korean Society of Remote Sensing 2017 大韓遠隔探査學會誌 Vol.33 No.1
The detection of oil spills using radar image has been studied extensively. However, most of the proposed techniques have been focused on improving detection accuracy through the advancement of algorithms. In this study, research has been conducted to improve the accuracy of oil spill detection by improving the quality of radar images, which are used as input data to detect oil spills. Thresholding algorithms were used to measure the image improvement both before and after processing. The overall accuracy increased by approximately 16%, the producer accuracy increased by 40%, and the user accuracy increased by 1.5%. The kappa coefficient also increased significantly, from 0.48 to 0.92.
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Kim, Donghyeon,Lim, Daeseong,Ryu, Hyeonjeong,Lee, Jungjun,Ahn, Sung Il,Son, Bong Soo,Kim, Seung-Joo,Kim, Chang Hae,Park, Jung-Chul ACS AMERICAN CHEMICAL SOCIETY 2017 Inorganic Chemistry Vol.56 No.20
<P>Blue-emitting Ca2-xMgxSiO4:Ce (0.0 <= x <= 1.0) phosphors were successfully synthesized and characterized. Rietveld refinement revealed that four main phases exist within the solid-solution range of CaO-MgO-SiO2, namely, beta-Ca2SiO4 (Mg (x) = 0.0), Ca14Mg2(SiO4)(8) (Mg (x) = 0.25), Ca3Mg(SiO4)(2) (Mg (x) = 0.5), and CaMgSiO4 (Mg (x) = 1.0). The variation of the IR modes was more prominent with increasing Mg2+ content in the Ca2-xMgxSiO4 materials. The sharing of O atoms of the SiO4- tetrahedra by the MgO6-octahedra induced weakening of the Si O bonds, which resulted in the red shift of the [SiO4] internal modes and appearance of a Mg-O stretching vibration at similar to 418 cm(-1). Raman measurement revealed that the change of the Ca-O bond lengths because of the Mg2+-substitution directly reflected the frequency shift of the Si-O stretching-Raman modes. Notably, the thermal stability of Ca2-xMgxSiO4:Ce (Mg (x) > 0.0) phosphors was superior to that of beta-Ca2SiO4:Ce (Mg (x) = 0.0) as confirmed by temperature-dependent photoluminescence (PL) measurements. This indicated that Mg2+ ions play an important role in enhancement of the thermal stability. In combination with the results from PL and electroluminescence (EL), it was elucidated that the luminous efficiency of Ca2-xMgxSiO4:Ce (Mg (x) = 0.1) was approximately twice as much as beta-Ca2SiO4:Ce (Mg (x) = 0.00), directly indicating a 'Mg2+-substitution effect'. The large enhancements of PL, EL, and thermal stability because of Mg2+-substitution may provide a platform in the discovery of more efficient phosphors for NUV-LEDs.</P>
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Kim, Daeseong,Jung, Hyung-Sup The Korean Society of Remote Sensing 2018 大韓遠隔探査學會誌 Vol.34 No.4
In this paper, we derive i) a function to estimate snow cover fraction (SCF) from a MODIS satellite image that has a wide observational area and short re-visit period and ii) a function to determine snow depth from the estimated SCF map. The SCF equation is important for estimating the snow depth from optical images. The proposed SCF equation is defined using the Gaussian function. We found that the Gaussian function was a better model than the linear equation for explaining the relationship between the normalized difference snow index (NDSI) and the normalized difference vegetation index (NDVI), and SCF. An accuracy test was performed using 38 MODIS images, and the achieved root mean square error (RMSE) was improved by approximately 7.7 % compared to that of the linear equation. After the SCF maps were created using the SCF equation from the MODIS images, a relation function between in-situ snow depth and MODIS-derived SCF was defined. The RMSE of the MODIS-derived snow depth was approximately 3.55 cm when compared to the in-situ data. This is a somewhat large error range in the Republic of Korea, which generally has less than 10 cm of snowfall. Therefore, in this study, we corrected the calculated snow depth using the relationship between the measured and calculated values for each single image unit. The corrected snow depth was finally recorded and had an RMSE of approximately 2.98 cm, which was an improvement. In future, the accuracy of the algorithm can be improved by considering more varied variables at the same time.
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Comparison of Snow Cover Fraction Functions to Estimate Snow Depth of South Korea from MODIS Imagery
( Daeseong Kim ),( Hyung-sup Jung ),( Jeong-cheol Kim ) 대한원격탐사학회 2017 大韓遠隔探査學會誌 Vol.33 No.4
Estimation of snow depth using optical image is conducted by using correlation with Snow Cover Fraction (SCF). Various algorithms have been proposed for the estimation of snow cover fraction based on Normalized Difference Snow Index (NDSI). In this study we tested linear, quadratic, and exponential equations for the generation of snow cover fraction maps using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua satellite in order to evaluate their applicability to the complex terrain of South Korea and to search for improvements to the estimation of snow depth on this landscape. The results were validated by comparison with in-situ snowfall data from weather stations, with Root Mean Square Error (RMSE) calculated as 3.43, 2.37, and 3.99 cm for the linear, quadratic, and exponential approaches, respectively. Although quadratic results showed the best RMSE, this was due to the limitations of the data used in the study; there are few number of in-situ data recorded on the station at the time of image acquisition and even the data is mostly recorded on low snowfall. So, we conclude that linear-based algorithms are better suited for use in South Korea. However, in the case of using the linear equation, the SCF with a negative value can be calculated, so it should be corrected. Since the coefficients of the equation are not optimized for this area, further regression analysis is needed. In addition, if more variables such as Normalized Difference Vegetation Index (NDVI), land cover, etc. are considered, it could be possible that estimation of national-scale snow depth with higher accuracy.
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Comparison of Snow Cover Fraction Functions to Estimate Snow Depth of South Korea from MODIS Imagery
Kim, Daeseong,Jung, Hyung-Sup,Kim, Jeong-Cheol The Korean Society of Remote Sensing 2017 大韓遠隔探査學會誌 Vol.33 No.4
Estimation of snow depth using optical image is conducted by using correlation with Snow Cover Fraction (SCF). Various algorithms have been proposed for the estimation of snow cover fraction based on Normalized Difference Snow Index (NDSI). In this study we tested linear, quadratic, and exponential equations for the generation of snow cover fraction maps using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua satellite in order to evaluate their applicability to the complex terrain of South Korea and to search for improvements to the estimation of snow depth on this landscape. The results were validated by comparison with in-situ snowfall data from weather stations, with Root Mean Square Error (RMSE) calculated as 3.43, 2.37, and 3.99 cm for the linear, quadratic, and exponential approaches, respectively. Although quadratic results showed the best RMSE, this was due to the limitations of the data used in the study; there are few number of in-situ data recorded on the station at the time of image acquisition and even the data is mostly recorded on low snowfall. So, we conclude that linear-based algorithms are better suited for use in South Korea. However, in the case of using the linear equation, the SCF with a negative value can be calculated, so it should be corrected. Since the coefficients of the equation are not optimized for this area, further regression analysis is needed. In addition, if more variables such as Normalized Difference Vegetation Index (NDVI), land cover, etc. are considered, it could be possible that estimation of national-scale snow depth with higher accuracy.
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( Daeseong Kim ),( Hyung-sup Jung ) 대한원격탐사학회 2018 大韓遠隔探査學會誌 Vol.34 No.4
In this paper, we derive i) a function to estimate snow cover fraction (SCF) from a MODIS satellite image that has a wide observational area and short re-visit period and ii) a function to determine snow depth from the estimated SCF map. The SCF equation is important for estimating the snow depth from optical images. The proposed SCF equation is defined using the Gaussian function. We found that the Gaussian function was a better model than the linear equation for explaining the relationship between the normalized difference snow index (NDSI) and the normalized difference vegetation index (NDVI), and SCF. An accuracy test was performed using 38 MODIS images, and the achieved root mean square error (RMSE) was improved by approximately 7.7 % compared to that of the linear equation. After the SCF maps were created using the SCF equation from the MODIS images, a relation function between in-situ snow depth and MODIS-derived SCF was defined. The RMSE of the MODIS-derived snow depth was approximately 3.55 cm when compared to the in-situ data. This is a somewhat large error range in the Republic of Korea, which generally has less than 10 cm of snowfall. Therefore, in this study, we corrected the calculated snow depth using the relationship between the measured and calculated values for each single image unit. The corrected snow depth was finally recorded and had an RMSE of approximately 2.98 cm, which was an improvement. In future, the accuracy of the algorithm can be improved by considering more varied variables at the same time.
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Effects of Beryllium on Human Serum Immunoglobulin and Lymphocyte Subpopulation
Kim, Ki-Woong,Kim, DaeSeong,Won, Yong Lim,Kang, Seong-Kyu Korean Society of ToxicologyKorea Environmental Mu 2013 Toxicological Research Vol.29 No.2
To investigate the effects of short-term exposure of beryllium on the human immune system, the proportion of T-lymphocytes such as CD3+, CD4+, CD8+, CD95, and NK cells, and the proportion of B cells and $TNF{\alpha}$ level in peripheral blood and immunoglobulins in the serum of 43 exposed workers and 34 healthy control subjects were studied. External exposure to beryllium was measured by atomic absorption spectrometer as recommended by the NIOSH analytical method 7300. T lymphocyte subpopulation analysis was carried out with flow cytometer. The working duration of exposed workers was less than 3 months and the mean ambient beryllium level was $3.4{\mu}g/m^3$, $112.3{\mu}g/m^3$, and $2.3{\mu}g/m^3$ in molding (furnace), deforming (grinding), and sorting processes, respectively (cited from Kim et al., 2008). However, ambient beryllium level after process change was non-detectable (< $0.1{\mu}g/m^3$). The number of T lymphocytes and the amount of immunoglobulins in the beryllium-exposed workers and control subjects were not significantly different, except for the total number of lymphocytes and CD95 (APO1/FAS). The total number of lymphocytes was higher in the beryllium-exposed individuals than in the healthy control subjects. Multiple logistic regression analysis showed lymphocytes to be affected by beryllium exposure (odd ratio = 7.293; p<0.001). These results show that short-term exposure to beryllium does not induce immune dysfunction but is probably associated with lymphocytes proliferation.
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