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We report the rearrangement of abietane core with trifluoromethanesulfonic anhydride in pyridine to afford the icetexane core, a key intermediate for total syntheses of the structurally intriguing and biologically active compounds (±)-barbatusol, (±)-rosmaridiphenol, and (±)-pisiferin.

We synthesized [6,6,6]- and [6,6,7]-tricyclic compounds via intramolecular [4+2] cycloaddition by gold or copper catalysts. Substrates for cyclization were prepared by coupling reactions between eight types of diyne and four types of aromatic moieties. We have successfully synthesized eleven tricyclic compounds.

We report the short synthesis of two natural products, rosmaridiphenol and taxamairin B, from key intermediates 5a and 5b, which were prepared from enynals 8a and 9b, respectively, by using a gold-catalyzed cyclization reaction. This approach can be widely applied in the synthesis of [6,7,6]-fused tricyclic compounds found in many icetexane diterpenoids.

An efficient and facile method for producing 2,3-dihydronaphtho[2,3-b]furan and 3,4-dihydro-2H-benzo[g]chromene has been developed. This methodology utilizes an inexpensive and simple PTSA catalyst for the cyclization reaction of ortho-oxalate-, ortho-keto-, and ortho-formyl arylacetylenols to produce the corresponding products in high yield. This procedure was also successfully applied to the large-scale synthesis of the naphthofuran skeleton, which can be found in various natural products and pharmaceuticals.

A practical and efficient approach for the total synthesis of arucadiol and 1-oxomiltirone is reported. The key step which involves an intramolecular [4+2] cycloaddition catalyzed by gold(III) bromide or copper(II) triflate leads to the formation of 6-6-6-fused aromatic abietane core.

This work was supported by a grant from the National Research Foundation of Korea (NRF), funded by the Korean Government, through Individual Research, Mid-career Research Program (NRF2017R1 A2B4003211).

For the design of the semiconductor packaging material, one of the most important challenges is to overcome the higher thermal expansion property of ‘organic’ epoxy composite than that of the ‘inorganic’ IC chip. Therefore, in order to prepare the epoxy composite with the ultra-low coefficient of thermal expansion (CTE), the new material class of epoxy, i.e., alkoxysilyl-functionalized novolac epoxy (Si(OEt)3-EOCN) was synthesized using the ortho-cresol novolac epoxy (EOCN) as a starting material. The new epoxy composite with the 85wt% of silica showed the CTE1 (at T Tg) of 11 ppm/°C. Note that before alkoxysilyl-modification, the CTE1 and CTE 2 of the EOCN composite were 13 ppm/°C and 44 ppm/°C, respectively. In addition, the alkoxysilyl-functionalized epoxy was observed to show the unique curing chemistry due to the participation of alkoxysilyl group in epoxy curing reaction. In order to understand the chemistry of alkoxysilyl-functionalized epoxy, the reaction mechanism was studied using the model compounds.

The high coefficient of thermal expansion (CTE) of the epoxy composite frequently causes the CTE-mismatch problem in semiconductor packaging. However, when the epoxy resins available currently are used for composite, the CTE-mismatch problem is inevitable even at the highly-filled conditions. In this study, the new type of bisphenol A (BPA) epoxy resin, i.e., ethoxysilyl-functionalized BPA epoxy was synthesized for the ultra-low CTE epoxy composite. The new epoxy composite with 85 wt% of silica content showed the ultra-low CTE of 3.2 ppm/°C and 6.0 ppm/°C at the temperature ranges of T Tg, respectively. For comparison, the non-functionalized BPA epoxy composite was prepared under the similar conditions and it showed the CTE values of 8 ppm/°C and 40 ppm/°C at the temperature ranges of T Tg, respectively. In order to understand the unique feature of the alkoxysilyl-functionalized epoxy, the reaction mechanism of the new epoxy was investigated using the model compound.

A simple, mild, efficient and chemoselective catalytic method for the straightforward synthesis of an interesting class of 2-aryl/alkyl-substituted-3-diaryl indolyl methanes in high yield is reported. This atom-efficient method proceeds via a gold-catalyzed one-pot sequential intramolecular hydroamination (C–N bond formation) of 2-alkynylanilines followed by a 1,6-conjugate addition to p-quinonemethides. The p-quinonemethides, which contain aldehyde functional groups, preferentially participate in 1,6-conjugate addition, while the aldehyde functional group remains unreactive.

A simple, mild, catalytic and efficient method for the straightforward synthesis of an interesting class of 2-aryl/alkyl-substituted-3-indolyl quinones in good to high yields is reported for the first time. This atom-efficient method proceeds via copper-catalyzed one-pot sequential intramolecular hydroamination (C–N bond formation) of 2-alkynylanilines followed by oxidative C–C coupling with benzoquinones.

Heteroaromatic-anchored enynals with a pendent alkene group were successfully cyclized through a Huisgen-type [3+2] cycloaddition to give a tetracyclic Pt–carbene complex that underwent insertion into the C–H bond in the β-position to give fused cyclopropanes that are otherwise inaccessible. On heating, the cyclopropanes smoothly rearranged to form the corresponding heterospiranes with excellent levels of stereoselectivity and high yields.

The structure analysis explains that the gold-catalyzed reaction forms one benzene ring possessing an acetoxyethenyl and an acetoxy groups in 2 and 4 positions. Based on the X-ray analysis, we revised structures of all products reported previously in two papers. The proposed mechanism of this sequence is being revised with an evidence of gold-carbene intermediacy. The proposed gold-carbene intermediate was supported by the control experiment for enyne metathesis route.

We report an improved 3-stacked white organic light emitting diode (WOLED) structure comprised of layers emitting red and yellow-green phosphorescence in the 2nd stacked device. We focused on developing the WOLED devices to realize 4K premium OLED TV displaying very high brightness and excellent color characteristics, with the optimized color layer. The WOLED has a high current efficiency of 83 cd/A, and cool white color whose color coordinate is (0.297, 0.317). 65-inch 4K premium OLED TV employing the new WOLED shows 800 nit of peak brightness, and 99 percent color gamut in DCI color space.

In this paper, we present OLED display technologies for large-size and premium TVs. Since high-quality TV needs total accuracy to reproduce input images, OLED panels must achieve stable luminance, uniformity at low luminance, and color uniformity. Using various OLED and TFT compensation technologies, we have successfully developed an OLED display with the “Real Black” image quality and high color uniformity. Additionally we have been developing OLED displays for broadcast monitors, which require much higher image quality than commercial TVs. We are now focusing on cost competitiveness of premium OLED displays.

The fast pyrolysis of biomass, empty fruit bunches from the palm mill industries, was conducted in a lab-scale bubbling fluidized bed reactor with a throughput of 1 kg/hr at temperatures ranging from 400 to 650 °C. For producing a higher yield of bio-crude oil with better homogeneity, washing methods were applied to the empty fruit bunch with water and nitric acid to remove ash and alkali and alkaline earth metallic species. After washing, the ash content decreased from 5.9 to 1.53 wt%, and over 80 wt% of alkali and alkaline earth metals, such as potassium, magnesium, calcium, and sodium, was removed. For considering economic feasibility and efficiency, the biomass treated with tap water for 1 day could be enough to produce oil with the highest yield of 48 wt% at 500 °C. The homogeneity of bio-crude oil produced by fast pyrolysis from the empty fruit bunches with nitric acid washing increased to 98%. The results of chemical compounds in oil could also confirm such quality improvement by less number and higher fraction of phenol compounds.

We previously reported a novel Au-catalyzed sequential activation of two different propargyl carboxylates to 6-methylene-6H-benzo[7]annulene-5,8-diyl dicarboxylates. This reaction has been extended to syntheses of highly functionalized 2,2′-bibenzo[7]annulenes with four biphenyls bearing two sets of different propargyl carboxylates.

A formal synthesis of komaroviquinone has been accomplished by utilizing the Pt-catalyzed hydrative cyclization of an enynal that was easily prepared in a convergent manner. The Pt-catalyzed hydrative cyclization reaction afforded the corresponding tricyclic product, which was utilized in the synthesis of a known precursor that led to the formation of komaroviquinone through an additional four-step synthesis.

In this paper, we present novel organic light-emitting diode (OLED) display panel compensation technologies for large-sized ultra-high-definition OLED TVs considering variations of threshold voltage, mobility, channel size, OLED efficiency, and OLED uniformity. Using these technologies, we have successfully launched 55-, 65- and 77-in. ultra-high-definition OLED TVs.

In this paper, we present advanced OLED display technologies for large-size semi-flexible TVs, including a coplanar TFT backplane, a high-performance RGBW structure, compensation technologies and a high dynamic range technology for enhancing image qualities. By using them we have developed various displays and TVs such as curved, transparent, dual plate, and semi-flexible display applications. Currently we concentrate on technologies for premium displays and cost competitiveness for UHD OLED TVs.

This paper will explain recent progress of WOLED for OLED TV which has been made by introducing an additional blue unit to conventional 2- stack tandem WOLED consisting of blue and yellow green (YG) devices. The addition of the blue unit not only boosts blue subpixel efficiency, but also makes the correlated color temperature of WOLED increase, resulting in more energy-efficient OLED TV. How the detailed architecture in the 3-stack WOLED is determined will be described, in consideration of color shift dependent on a viewing angle.

OLEDs have excellent ambient contrast, because OLEDs with a circular polarizer can effectively reduce the reflectance caused by external light. However, for better blackness, it is necessary to improve reflectance and reflection color. By applying new material, blackness of OLED TV is improved.

To circumvent the adverse impacts arising from an excessive use of fossil fuels, bioenergy and chemical production from a carbon neutral resource (biomass) has drawn considerable attention over the last two decades. Among various technical candidates, fast pyrolysis of biomass has been considered as one of the viable technical routes for converting a carbonaceous material (biomass) into biocrude (bio-oil). In these respects, three biomass samples (i.e., sawdust, empty fruit bunch, and giant Miscanthus) were chosen as a carbon substrate for the pyrolysis process in this study. A pilot-scale circulating fluidized bed reactor was employed for the pyrolysis work, and biocrude from the fast pyrolysis process at 500 °C were characterized because the maximum yield of biocrude (60 wt% of the original sample mass) was achieved at 500 °C. The physico-chemical properties of biocrude were measured by the international standard/protocol (ASTM D7544 and/or EN 16900 test method) to harness biocrude as bioenergy and an initial feedstock for diverse chemicals. All measurements in this study demonstrated that the heating value, moisture content, and ash contents in biocrude were highly contingent on the type of biomass. Moreover, characterization of biocrude in this study significantly suggested that additional unit operations for char and metal removal must be conducted to meet the fuel standard in terms of biocrude as bioenergy.

This study experimentally investigates fundamental phenomena in the HTGR small break air-ingress accident. Several important parameters including density ratio, break angle, break size, and main flow velocity are considered in the measurement and the analysis. The test-section is made of a circular pipe with small holes drilled around the surface and it is installed in the helium/air flow circulation loop. Oxygen concentrations and flow rates are recorded during the tests with fixed break angles, break sizes, and flow velocities for measurement of the air-ingress rates. According to the experimental results, the higher density difference leads to the higher rates of air-ingress with large sensitivity of the break angles. It is also found that the break angle significantly affects the air-ingress rates, which is gradually increased from 0° to 120° and suddenly decreased to 180°. The minimum air ingress rate is found at 0° and the maximum, at 110°. The air-ingress rate increases with the break size due to the increased flow-exchange area. However, it is not directly proportional to the break area due to the complexity of the phenomena. The increased flow velocity in the channel inside enhances the air-ingress process. However, among all the parameters, the main flow velocity exhibits the lowest effect on this process. In this study, the Froude Number relevant to the small break air-ingress conditions are newly defined considering both heavy and light fluids, and break angles. Based on this definition, the experimental data can be well re-arranged and collected. Finally, this study develops and proposes a non-dimensional parameter and a criteria for determination of the small break air-ingress flow regimes. As a result, the non-dimensional parameter higher than 0.49 indicates that the air-ingress is mainly controlled by density gradient effect. On the other hand, that lower than 0.47 indicates that the other effects such as inertia or diffusion are dominant air-ingress mechanisms.

We have developed the world's first 65-inch UHD (also called 4K, 3840×2160) OLED TV with a coplanar-type IGZO(Indium Gallium Zinc Oxide) TFTs. In this paper, we discuss our excellent WRGB panel designs and circuits to achieve the high frame frequency and the product reliability.