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761 results on '"Kim, W. H."'

56. The U-shaped association between achieved blood pressure and risk of cardiovascular events and mortality in elderly and younger patients

Author

Lim, N, Park, H, Kim, W, Mancia, G, Cho, M, Lim N. -K., Park H. -Y., Kim W. -H., Mancia G., Cho M. -C., Lim, N, Park, H, Kim, W, Mancia, G, Cho, M, Lim N. -K., Park H. -Y., Kim W. -H., Mancia G., and Cho M. -C.

Abstract

Objective:The main objective is to assess the appropriate level of achieved SBP and DBP to prevent cardiovascular events.Methods:We used the National Sample Cohort from the National Health Insurance Service in Korea and analyzed data of 44462 hypertensive patients aged 20 - 84 years. Achieved SBP and DBP were categorized according to average achieved SBP (<120, 120-129, 130-139, 140-149, and ≥150mmHg) and DBP (<70, 70-79, 80-89, 90-99, and ≥100mmHg). We examined the association between achieved BP and composite outcome including cardiovascular death, admission of stroke, myocardial infarction, or heart failure, and all-caused death in elderly aged more than 65 years and in younger patients.Results:After a median follow-up of 6.8 years, achieved SBP less than 120mmHg and at least 150mmHg in elderly and younger patients, respectively, were significantly associated with a higher risk of composite outcome than achieved SBP of 120-129mmHg. Cox's proportional hazard analysis showed that the association between achieved SBP and risk of composite outcome and all-cause death had U-shaped relationships and identified a nadir of SBP of 135.6 and 128.9mmHg, respectively, for composite outcome and 135.1 and 131.4mmHg, respectively, for all-cause death in elderly and younger patients.Conclusion:Compared with SBP of 120-129mmHg, not only low achieved SBP of less than 120mmHg but also high BP are associated with risk of adverse cardiovascular event and all-cause death in both elderly and younger patients with a distinct U-shaped relationship.

Published
2020

57. Characterization of Mid-Infrared Single Mode Fibers as Modal Filters

Author

Ksendzov, A, Lay, O, Martin, S, Sanghera, J. S, Busse, L. E, Kim, W. H, Pureza, P. C, Nguyen, V. Q, and Aggarwal, I. D

Subjects
Optics
Abstract

We present a technique for measuring the modal filtering ability of single mode fibers. The ideal modal filter rejects all input field components that have no overlap with the fundamental mode of the filter and does not attenuate the fundamental mode. We define the quality of a nonideal modal filter Q(sub f) as the ratio of transmittance for the fundamental mode to the transmittance for an input field that has no overlap with the fundamental mode. We demonstrate the technique on a 20 cm long mid-infrared fiber that was produced by the U.S. Naval Research Laboratory. The filter quality Q(sub f) for this fiber at 10.5 micron wavelength is 1000 +/- 300. The absorption and scattering losses in the fundamental mode are approximately 8 dB/m. The total transmittance for the fundamental mode, including Fresnel reflections, is 0.428 +/- 0.002. The application of interest is the search for extrasolar Earthlike planets using nulling interferometry. It requires high rejection ratios to suppress the light of a bright star, so that the faint planet becomes visible. The use of modal filters increases the rejection ratio (or, equivalently, relaxes requirements on the wavefront quality) by reducing the sensitivity to small wavefront errors. We show theoretically that, exclusive of coupling losses, the use of a modal filter leads to the improvement of the rejection ratio in a two-beam interferometer by a factor of Q(sub f).

Published
2007
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79. P2690The bleeding and cardiovascular risk according to NSAIDs selectivity in patients receiving antithrombotics and concomitant NSAIDs after myocardial infarction: a nationwide cohort study

Author

Park, E J, primary, Kim, W H, additional, Choi, J Y, additional, Jang, W Y, additional, Na, J O, additional, Choi, J I, additional, Kim, J W, additional, Kim, E J, additional, Rha, S W, additional, Park, C G, additional, Seo, H S, additional, and Choi, C U, additional

Published
2018
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82. Determination of the width of the carrier recombination zone in organic light-emitting diodes.

Author

Kalinowski, J., Palilis, L. C., Kim, W. H., and Kafafi, Z. H.

Subjects
ALUMINUM, LIGHT emitting diodes, SEMICONDUCTORS, ELECTRIC fields, QUANTUM electronics
Abstract

Bilayer organic light-emitting diodes based on tris-(8-hydroxyquinolinato) aluminum III have been fabricated where the thickness of the light-emitting layer was varied between 10 and 80 nm while maintaining a constant total thickness of the organic layers. The electroluminescence quantum efficiency of the devices was measured as a function of the emitter thickness, and used to determine the width of the carrier recombination zone at different electric fields. The width of the carrier recombination zone is found to decrease with an increase in electric field [from 70 nm (E=0.75 MV/cm) to 40 nm (E=1.0 MV/cm)]. It is also related to the field-dependent carrier injection efficiency. An estimate of the light output coupling factor (0.4) is also given based on this analysis. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2003
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83. Highly oriented indium tin oxide films for high efficiency organic light-emitting diodes.

Author

Kim, H., Horwitz, J. S., Kim, W. H., Kafafi, Z. H., and Chrisey, D. B.

Subjects
INDIUM, LIGHT emitting diodes, THIN films
Abstract

Highly oriented indium tin oxide (ITO) thin films were grown by pulsed-laser deposition (PLD) on glass and single-crystal yttria-stabilized zirconia (YSZ) substrates. The structural, electrical, and optical properties of these films were investigated as a function of oxygen partial pressure. Films were deposited at substrate temperature of 300 °C in mixed gases (12 mTorr of argon and 1–50 mTorr of oxygen) using a KrF excimer laser (248 nm and 30 ns full width at half maximum) at a fluence of 1.2 J/cm2. ITO films (300 nm thick), deposited by PLD on YSZ at 300 °C in a gas mixture of 12 mTorr of argon and 6 mTorr of oxygen, exhibit a low electrical resistivity (1.6×10[sup -4] Ω cm) with a high transparency (∼74%) at 550 nm. ITO films deposited on both glass and YSZ substrates have been used as an anode contact in organic light-emitting diodes. A comparison of the device performance for the two substrates shows that the device fabricated on the ITO/YSZ has a higher external quantum efficiency than that of the device fabricated on the ITO glass. [ABSTRACT FROM AUTHOR]

Published
2002
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84. Area-selective atomic layer deposition of metal oxides on noble metals through catalytic oxygen activation

Author

Singh, J. (Joseph), Thissen, N.F.W., Kim, W.-H., Johnson, H., Kessels, W.M.M., Bol, A.A., Bent, S.F., Mackus, A.J.M., Singh, J. (Joseph), Thissen, N.F.W., Kim, W.-H., Johnson, H., Kessels, W.M.M., Bol, A.A., Bent, S.F., and Mackus, A.J.M.

Abstract

Area-selective atomic layer deposition (ALD) is envisioned to play a key role in next-generation semiconductor processing and can also provide new opportunities in the field of catalysis. In this work, we developed an approach for the area-selective deposition of metal oxides on noble metals. Using O2 gas as co-reactant, area-selective ALD has been achieved by relying on the catalytic dissociation of the oxygen molecules on the noble metal surface, while no deposition takes place on inert surfaces that do not dissociate oxygen (i.e., SiO2, Al2O3, Au). The process is demonstrated for selective deposition of iron oxide and nickel oxide on platinum and iridium substrates. Characterization by in situ spectroscopic ellipsometry, transmission electron microscopy, scanning Auger electron spectroscopy, and X-ray photoelectron spectroscopy confirms a very high degree of selectivity, with a constant ALD growth rate on the catalytic metal substrates and no deposition on inert substrates, even after 300 ALD cycles. We demonstrate the area-selective ALD approach on planar and patterned substrates and use it to prepare Pt/Fe2O3 core/shell nanoparticles. Finally, the approach is proposed to be extendable beyond the materials presented here, specifically to other metal oxide ALD processes for which the precursor requires a strong oxidizing agent for growth.

Published
2018

97. A New Direction for III–V FETs for Mobile CPU Operation Including Burst-Mode: In0.35Ga0.65As Channel

Author

Rakshit, T., primary, Obradovic, B., additional, Wang, W.-E., additional, Kim, W.-H., additional, Shin, K.-M., additional, Baek, S.-C., additional, Lee, S.-W., additional, Kim, S.-H., additional, Lee, J.-M., additional, Kim, D., additional, Hoover, A., additional, Song, W.-B., additional, Cantoro, M., additional, Heo, Y.-C., additional, Rooyackers, R., additional, Ardila, S. C., additional, Vais, A., additional, Lin, D., additional, Collaert, N., additional, and Rodder, M. S., additional

Published
2017
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99. Electronic dephasing of APT in glassy films of water from 5 to 100 K: Implications for H-bonding liquids.

Author

Reinot, T., Kim, W.-H., Hayes, J. M., and Small, G. J.

Subjects
*ELECTRONS, *METALLIC glasses, *HYDROGEN bonding, *AMMONIUM paratungstate
Abstract

Nonphotochemical hole burning was used to characterize the linear electron–phonon coupling and measure the temperature dependence of the pure electronic dephasing of Al-phthalocyanine tetrasulphonate (APT) in unannealed and annealed hyperquenched glassy films of water (HGW). Below about 10 K, the dephasing is dominated by coupling to the intrinsic two-level systems (TLSint) of HGW. This dephasing is a factor of 5× faster for unannealed HGW due to its higher TLSint number density. For annealed HGW, the pure electronic dephasing time (i.e., that dephasing associated with the zero-phonon line), T2*, is 6.4 ns at 5 K, the slowest dephasing time yet reported for a molecular glassy system at this temperature. At higher temperatures, dephasing due to exchange coupling with pseudolocalized modes at 50 and 180 cm-1, which correlate well with the transverse and longitudinal acoustic modes of water, becomes dominant. The exchange coupling mechanism is based on diagonal quadratic electron–phonon coupling. At 100 K, for example, the pure electronic dephasing times (T2*) are close to 1 ps in value for both types of film. Whereas the transverse acoustic mode is Franck–Condon active (S∼0.5), the 180 cm-1 mode is silent (S<0.02). The determination of the electron–phonon coupling parameters and static inhomogeneous broadening (400 cm-1) of APT’s origin band allowed for simulation of the burn temperature dependence of the overall hole profile (zero-phonon hole plus phonon-sideband holes). Comparison with experimental profiles shows that the hole profile theory of Hayes et al. [J. Phys. Chem. 98, 7337 (1994)] captures the main features of the temperature dependence.The S value of the transverse acoustic mode is used to quantitatively explain the burn temperature dependence of the saturated intensity of the zero-phonon hole and its demise at temperatures just above 100 K (due to Franck–Condon forbiddeness). In view of the... [ABSTRACT FROM AUTHOR]

Published
1996
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