ENERGY CONSUMPTION, ECONOMIC DEVELOPMENT AND SOCIO-DEMOGRAPHIC FACTORS

Lee, Sang-Gon CONSORTIUM ON DEVELOPMENT STUDIES 1990 DYNAMIC TRANSFORMATION Vol.1990 No.-

Characteristics of Molybdenum as a Plasma-Generating Electrode

Lee, Sang-Heon,Kim, Nack Hwan,Kim, Gon-Ho,Bae, Byeongjun,Shin, Jun Seop,Park, Su-San,Yoon, Sung-Young,Hong, Youngki American Scientific Publishers 2016 Science Of Advanced Materials Vol.8 No.9

Effect of Charge Carrier Lipid on Skin Penetration, Retention, and Hair Growth of Topically Applied Finasteride-Containing Liposomes

( Sang Im Lee ),( Santhosh Kumar ),( Nagayya Sriraman ),( Srinivasan Shanmugam ),( Rengarajan Baskaran ),( Chul Soon Yong ),( Sang Kwon Yoon ),( Han Gon Choi ),( Bong Kyu Yoo ) 한국응용약물학회 2011 Biomolecules & Therapeutics(구 응용약물학회지) Vol.19 No.2

The aim of this study was to investigate the effect of charge carrier lipid on the skin penetration, retention, and hair growth of topically applied finasteride-containing liposomes. Finasteride-containing liposomes were prepared by traditional thin film hydration method using Phospholipon(R) 85 G and cholesterol with or without charge carrier lipid (1,2 dimyristoyl-sn-glycero-3-phosphate or 1,2-dioleoyl-trimethylammonium-propane for anionic and cationic charge, respectively). Freshly prepared finasteride-containing liposome suspension was applied on the hairless mouse skin, and skin penetration and retention were measured using Keshary-Chien diffusion cell. Non-liposomal formulation (ethanol 10% solution containing 0.5 mg/ml of FNS) was also used as a control. The amount of finasteride in the diffusion cell and mouse skin was measured by HPLC. The hair growth was evaluated using depilated male C57BL/6N mice. Mean particle size of all finasteride-containing liposomes was less than a micron, and polydispersity index revealed size homogeneity. Skin penetration and retention studies showed that significantly less amount of finasteride was penetrated when applied as anionic liposome while more amount of the drug was retained. Specifically, in liposome prepared with 10% anionic charge carrier lipid, penetration was 12.99 μg/cm2 while retention was 79.23 μg/cm2 after 24 h of application. In hair growth study, finasteride-containing anionic liposomes showed moderate efficacy, but the efficacy was not found when applied as cationic liposomes. In conclusion, topical application of finasteride using anionic liposome formulation appears to be useful option for the treatment of androgenetic alopecia to avoid systemic side effects of the drug.

Electrical Characteristics of Semi-Insulating Polycrystalline Oxygen-Doped Silicon SIPOS Thin films

Lee, Seaung Suk,Kim, Jong Choul,Choi, Jae Sung,Park, Hun Sub,Chun, Hui Gon,Oh, Kye Hwan. 대한전자공학회 1991 ICVC : International Conference on VLSI and CAD Vol.2 No.1

Electrical characteristics of SIPOS(Semi-Insulating Polycrystalline Oxygen Doped-Silicon) thin films deposited by low-pressure chemical vapor deposition(LPCVD) were investigated with different process conditions such as N₂O/SiH₄ gas ratio and deposition temperature. The deposition rate and refractive index decreased with increasing gas ratio. Activation energy of SIPOS reaction was 24.13 Kcal/mole. The SIPOS thin films typically showed high resistance of 8.6∼11 tera-ohm in the range of 610℃∼650℃ deposition temperature. A stable high value of resistance was obtained at the gas ratio of N₂O/SiH₄= 0.1. The results also showed that there were a little change in resistance with the resistor size. Moreover, the film sustained high resistance of about 1.2 tera-ohm even at 85℃. The apparent activation energy was 0.39 eV.

Factors that control heavy snowfalls in the eastern coast of Korea

Lee, Seoung Soo,Kim, Byung-Gon,Nam, Hyoung-Gu,Yum, Seong Soo,Choi, Yong-Sang,Jung, Chang-Hoon Chinese Geoscience Union 2018 TAO Vol.29 No.3

<P>This study examines mechanisms which control heavy snowfalls in the eastern coast of Korea. Previous observational studies have indicated that heavy snowfalls are caused by the advection of cold and dry air over the warm ocean off the eastern coast. Previous studies have not considered the effects of surface heat fluxes on heavy snowfalls. It is likely that the warm ocean produces strong surface heat fluxes that are able to invigorate convection and enhance precipitation. Motivated by this, this study examines not only the effect of the advection on heavy snowfalls but also that of surface heat fluxes and compare these two types of effects. In addition to this, this study looks into microphysical and dynamic processes which are associated with heavy snowfalls, considering that previous studies have not given us information on these processes. By running high-resolution simulations, this study finds that surface heat fluxes are a main driver of heavy snowfalls and the roles played by the advection in them are negligible. Surface heat fluxes induce strong updrafts and large deposition onto snow and cloud ice, which enables the efficient growth of snow and heavy snowfalls. This demonstrates that for better understanding of heavy snowfalls in the eastern coast of Korea, we have to better understand the surface processes that are linked to surface heat fluxes.</P>

Evaluation of bone formation and membrane degradation in guided bone regeneration using a 4-hexylresorcinol-incorporated silk fabric membrane

Lee, Sang-Woon,Um, In Chul,Kim, Seong-Gon,Cha, Min-Sang Korean Association of Maxillofacial Plastic and Re 2015 Maxillofacial Plastic Reconstructive Surgery Vol.37 No.-

Background: The aims of present study were (1) to evaluate new bone formation among the 4-hexylresorcinol (4HR)-incorporated silk fabric membrane (SFM), conventional SFM, and uncovered control groups and (2) to compare the amount of residual membrane between the 4HR-incorporated SFM and conventional SFM in a rabbit parietal defect model. Methods: Nine New Zealand white rabbits were used for this animal study. After the formation of a bilateral parietal bone defect (diameter 8.0 mm), either 4HR-incorporated SFM or conventional SFM was grafted into the defect. The defect in the control was left uncovered. New bone formation and the amount of residual membrane were evaluated by histomorphometry at 8 weeks after the operation. Results: The total amount of new bone was $37.84{\pm}8.30%$ in the control, $56.64{\pm}15.74%$ in the 4HR-incorporated SFM group, and $53.35{\pm}10.52%$ in the conventional SFM group 8 weeks after the operation. The differences were significant between the control and 4HR-incorporated SFM group (P = 0.016) and between the control and conventional SFM group (P = 0.040). The residual membrane was $75.08{\pm}10.52%$ in the 4HR-incorporated SFM group and $92.23{\pm}5.46%$ in the conventional SFM group 8 weeks after the operation. The difference was significant (P = 0.039). Conclusions: The 4HR-incorporated SFM and conventional SFM groups showed more bone regeneration than the control group. The incorporated 4HR accelerated the partial degradation of the silk fabric membrane in a rabbit parietal defect model 8 weeks after the operation.

Flavonoids Isolated from Korea <i>Citrus aurantium</i> L. Induce G2/M Phase Arrest and Apoptosis in Human Gastric Cancer AGS Cells

Lee, Do-Hoon,Park, Kwang-Il,Park, Hyeon-Soo,Kang, Sang-Rim,Nagappan, Arulkumar,Kim, Jin-A,Kim, Eun-Hee,Lee, Won-Sup,Hah, Young-Sool,Chung, Hyon-Jong,An, Su-Jin,Kim, Gon-Sup Hindawi Publishing Corporation 2012 Evidence-based Complementary and Alternative Medic Vol.2012 No.-

<P><I>Aim of the Study</I>. Citrus species is used in traditional medicine as medicinal herb in several Asian countries including Korea. Flavonioids became known as various properties, such as anti-oxidants, anti-inflammation and anti-cancer, and so forth. The present study, the anti-cancer effect of flavonioids isolated from <I>Citrus aurantium</I> L. in human gastric cancer AGS cells has been investigated. <I>Materials and Methods</I>. The anti-proliferative activity was assayed using MTT assay. Cell cycle analysis was done using flow cytometry and apoptosis detection was done using by hoechst fluorescent staining and Annexin V-propidium iodide double staining. Western blot was used to detect the expression of protein related with cell cycle and apoptosis. <I>Results</I>. Flavonoids isolated from <I>Citrus aurantium</I> L. have the effect of anti proliferation on AGS cells with IC50 value of 99 <I><I>μ</I></I>g/mL. Flavonoids inhibited cell cycle progression in the G2/M phase and decrease expression level of cyclin B1, cdc 2, cdc 25c. Flavonoids induced apoptosis through activate caspase and inactivate PARP. <I>Conclusions</I>. Flavonoids isolated from <I>Citrus aurantium</I> L. induced G2/M phase arrest through the modulation of cell cycle related proteins and apoptosis through activation caspase. These finding suggest flavonoids isolated from <I>Citrus aurantium</I> L. were useful agent for the chemoprevention of gastric cancer.</P>

Lewis acid-catalyzed Friedel-Crafts/Michael cascade reaction of <i>N</i>,<i>N</i>-dialkyl-3-vinylanilines with <i>N</i>-tosylaziridines for the stereoselective synthesis of highly functionalized tetrahydroisoquinolines

Lee, Sang Gyu,Sin, Seunghui,Kim, Seungyeon,Kim, Sung-Gon Elsevier 2018 Tetrahedron letters: the international organ for t Vol.59 No.15

<P><B>Abstract</B></P> <P>A Lewis acid-catalyzed Friedel-Crafts/Michael cascade reaction between <I>N</I>-dialkyl-3-vinylanilines and <I>N</I>-tosylaziridines has been developed for the stereoselective synthesis of tetrahydroisoquinolines (THIQs). The reaction using Gd(OTf)<SUB>3</SUB> as the Lewis acid catalyst was tolerant to the various <I>N</I>-dialkyl-3-vinylaniline and <I>N</I>-tosylaziridine substrates and provided access to 28 new, highly functionalized THIQs in typically high yields with moderate- to- excellent diastereoselectivities.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Concise synthesis of 1,3,4-trisubstituted tetrahydroisoquinolines (THIQs) is developed. </LI> <LI> The method involves Friedel-Crafts/Michael cascade reaction of <I>N</I>-dialkyl-3-vinylanilines with <I>N</I>-tosylaziridines. </LI> <LI> Gd(OTf)<SUB>3</SUB> is used as the Lewis acid catalyst. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Highly efficient green, blue, and white phosphorescent inverted organic light-emitting diodes by improving charge injection and balance

Lee, Hyunkoo,Maeng, Min-Jae,Hong, Jong-Am,Najnin, Rokeya,Moon, Jaehyun,Cho, Hyunsu,Lee, Jonghee,Yu, Byoung-Gon,Park, Yongsup,Cho, Nam Sung The Royal Society of Chemistry 2017 Journal of Materials Chemistry C Vol.5 No.38

<▼1><P>Highly efficient green, blue, and white phosphorescent inverted organic light-emitting diodes were demonstrated by improving charge injection and balance.</P></▼1><▼2><P>To improve the performance of inverted organic light-emitting diodes (OLEDs), we investigated the electrical, optical, and interfacial properties of three different lithium (Li)-doped electron transport materials (ETMs): tris(3-(3pyridyl)mesityl)borane (3TPYMB), 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene (TmPyPB), and 1,3-bis(3,5-dipyrid-3-yl-phenyl)benzene (BmPyPB). The electron injection barriers (EIBs) between indium-tin-oxide and the ETMs were deduced for both pristine and Li-doped cases from ultraviolet photoelectron spectroscopy measurements and optical band gap values. The Li-doped ETMs showed EIB values of approximately 0.03 eV, 0.77 eV, and 0.81 eV for 3TPYMB, TmPyPB, and BmPyPB, respectively, which are much lower than those of their pristine counterparts of 0.94 eV, 1.14 eV, and 1.48 eV, respectively. The Li-doped ETMs were employed as electron injection layers (EILs) of inverted bottom-emission OLEDs (IBE-OLEDs) with green phosphorescence. IBE-OLEDs with 3TPYMB, TmPyPB, and BmPyPB EILs exhibited driving voltages of 3.6 V, 4.0 V, and 4.5 V at 1000 cd m<SUP>−2</SUP> and maximum external quantum efficiencies (EQEs) of 20.3%, 19.7%, and 16.5%, respectively. From the low EIB of Li-doped 3TPYMB, we also demonstrated highly efficient blue and white phosphorescent IBE-OLEDs. We optimized the device structure to improve the charge balance and out-coupling efficiency by changing the hole injection layer and the thickness of the hole and electron transport layers with optical simulation. The blue device showed a maximum EQE and luminous current efficiency of 22.9% and 43.1 cd A<SUP>−1</SUP>, respectively. In addition, the white device exhibited a high EQE and luminous efficacy of 19.3% and 37.8 lm W<SUP>−1</SUP> at 3 mA cm<SUP>−2</SUP> (∼1000 cd m<SUP>−2</SUP>), respectively. To the best of our knowledge, the efficiencies of these green, blue, and white devices are the highest values obtained to date with a low driving voltage for IBE-OLEDs without any additional light-extraction structure. Since the Li-doped 3TPYMB has an extremely low EIB and shows good device performance, it can be utilized as an effective EIL in inverted-structure devices.</P></▼2>

Tolerance to carbon corrosion of various carbon structures as catalyst supports for polymer electrolyte membrane fuel cells

Lee, Sung Won,Choi, Sung Ryul,Jang, Jeongyun,Park, Gu-Gon,Yu, Seung Ho,Park, Jun-Young The Royal Society of Chemistry 2019 Journal of Materials Chemistry A Vol.7 No.43

<P>To overcome the stability issue at high voltages related to the carbon corrosion of polymer electrolyte membrane fuel cells, different types of platelet carbon nanofibers (PCNFs) featuring a wide range of fiber stems are employed as a Pt catalyst supporting material. Further, PCNFs are hybridized with spherical activated carbons (SC) as a Pt support to improve the electrocatalytic activity of the catalysts by increasing the surface area and electrical conductivity with well-distributed meso- and macro-pores, while maintaining tolerance to carbon corrosion of electrocatalysts. Tafel slopes of the catalysts for the kinetic current of electrocatalysts are in the order of Pt/PCNF (−58.2 mV dec<SUP>−1</SUP>) < Pt/Hybrid (−57.0 mV dec<SUP>−1</SUP>) < Pt/SC (−54.3 mV dec<SUP>−1</SUP>), showing the rapid kinetics of Pt/SC and Pt/Hybrid for the oxygen reduction reaction. The Pt catalysts are subjected to accelerated stress tests (AST) in which the cell voltage is cycled between 1.0 and 1.5 V in 2 s (1 cycle), and the Pt/PCNF and Pt/Hybrid catalysts are highly durable in carbon-corrosion durability testing. Furthermore, the MEAs with the Pt/PCNF, Pt/SC, and Pt/Hybrid catalysts are operated at 65 °C, and the maximum power densities of MEAs were 0.708, 0.674, and 0.507 W cm<SUP>−2</SUP> for Pt/SC, Pt/Hybrid, and Pt/PCNF, respectively, as is consistent with the characteristics of catalysts. The MEAs are also subjected to AST at 80 °C, and a relatively small performance decay occurred at 0.6 V for the Pt/PCNF (36.2%) and Pt/Hybrid MEAs (44.0%), but considerably more degradation was observed for Pt/SC MEA (73.2%), signifying that the mechanochemically durable PCNF effectively prevented carbon corrosion with Pt agglomeration.</P>