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K Jeon,
W-I Choi,
J S An,
S Y Lim, W J Kim,
G M Park,
S S Park,
H S Choi,
B H Lee,
J C Choi,
M J Na,
J Park,
J Y Kim
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ABSTRACT: To evaluate the incidence, clinical characteristics and predicting factors for the development of paradoxical response in human immunodeficiency virus negative patients with isolated pleural tuberculosis (TB).
A multicentre, retrospective cohort study including 458 patients who were diagnosed and treated with isolated pleural TB between March 2005 and February 2010.
Paradoxical response developed in 72 patients (16%) with isolated pleural TB. The mean time to development of paradoxical response was 8.8 ± 6.4 weeks after initiation of anti-tuberculosis treatment. The main presentation of paradoxical response was aggravation of pre-existing pleural effusion in 58 patients (81%). However, the majority of the patients who developed paradoxical response had no associated symptoms (n = 49, 68%). In multiple logistic regression analysis, development of paradoxical response was independently associated with the proportion of eosinophils (adjusted OR 1.293, 95%CI 1.077-1.553) and protein concentrations (adjusted OR 0.590, 95%CI 0.397-0.878) in the pleural fluid at the time of diagnosis.
Paradoxical response developed in 16% of the patients approximately 2 months after initiation of anti-tuberculosis treatment, presenting with aggravation of pre-existing pleural effusion. Development of paradoxical response was associated with the proportion of eosinophils and protein concentrations in the pleural fluid at the time of diagnosis.
The international journal of tuberculosis and lung disease: the official journal of the International Union against Tuberculosis and Lung Disease 04/2012; 16(6):846-51. · 2.73 Impact Factor
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Y. Kim,
S.C. Oh,
W.C. Lim,
J.H. Kim, W.J. Kim,
J.H. Jeong,
H.J. Shin,
K.W. Kim,
K.S. Kim,
J.H. Park,
S.H. Park,
H. Kwon,
K.H. Ah,
J.E. Lee,
S.O. Park,
S. Choi,
H.K. Kang,
C. Chung
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ABSTRACT: 28nm MTJ for 8~16Gb MRAM device has been successfully integrated with special patterning & etch technique. Resistance (R) separation between high and low R states was 15.2σ, comparable to that for 80nm MTJ cells. Thermal stability factor (Δ) followed prediction fairly well, and MTJ with free layer (FL) of 25Å and aspect ratio (AR) of 3 showed Δ of 56. In order to realize sub-30nm MRAM device, a novel FL with substantially low critical current density (J<sub>c</sub>) or revolutionary MTJ scheme needs to be developed.
VLSI Technology (VLSIT), 2011 Symposium on; 07/2011
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ABSTRACT: Feasibility of STT-MRAM (Spin-Transfer Torque Magnetic Random Access Memory) as next generation non-volatile memory has been tested for the replacement of DRAM and NOR Flash. For competition with DRAM, STT-MRAM unit cell size should be reduced to 6 ~ 8F<sup>2</sup> and switching current density is required to be less than 1 MA/cm<sup>2</sup>. Here, we report that the cell characteristics of on-axis STT-MRAM with 6 ~ 8F<sup>2</sup> are similar to those of off-axis STT-MRAM with 12 ~ 16F<sup>2</sup>. In addition, we suggest a novel MTJ (Magnetic Tunnel Junction) with the operation current density of 0.8 MA/cm<sup>2</sup>. These results open a way to scale STT-MRAM down to sub- 30 nm technology node using present technology. By further material engineering of ferromagnetic electrode and MTJ structure design, the usage of present technology could be extended down to sub-20 nm node.
Electron Devices Meeting (IEDM), 2010 IEEE International; 01/2011
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ABSTRACT: Design and relay-based control of a novel linear magnetostrictive motor is presented in this paper. The magnetostrictive material used here is Terfenol-D, an alloy of the formula Tb<sub>0.3</sub>Dy<sub>0.7</sub>Fe<sub>1.9</sub>. In response to a traveling magnetic field inside the Terfenol-D element, it moves in the opposite direction with a peristaltic motion. The proposed design offers the flexibility to operate the motor in various configurations including local and conventional three-phase excitation. In this paper, we demonstrate that the power consumption can be reduced significantly by the local-excitation approach. A new force transmission assembly incorporates spring washers to avoid the wear due to its sudden collision with the Terfenol-D element. The closed-loop control system was implemented using relay control which resulted in an optimal closed-loop performance. The magnetostrictive motor has demonstrated 410-N load capacity with a travel range of 45 mm, and the speed is around 9 mm/min currently. The low speed is due to the local three-phase operation mode, and it could be increased to 60 mm/min by using the conventional three-phase operation. The maximum power consumption by the motor is 95 W.
American Control Conference, 2009. ACC '09.; 07/2009
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S.Y. Han,
J.M. Park,
S.O. Sohn,
J.B. Lee,
K.S. Chae,
C.H. Jeon,
J.S. Park,
S.D. Kim, W.J. Kim,
S. Yamada,
Y.P. Kim,
H.S. Park,
N.M. Cho,
H.H. Kim,
M.S. Lee,
Y.S. Lee,
W. Yang,
Donggun Park,
Byung-il Ryu
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ABSTRACT: The pad-polysilicon side contact (PSC) has drastically improved the performance of the partially-insulated bulk FinFET (Pi-FinFET). PSC enabled to dope a source and drain (S/D) of the fin structure uniformly from the top of the fin to the Pi layer. Since the uniform S/D increases effective channel width, the drivability was increased by 100% compared to the conventional bulk FinFET cell. Nevertheless, hot carrier (HC) lifetime was extended because the position of the highest electric field was nearer to the gate edge compared to the conventional. The total junction leakage current became 50% of the conventional due to the Pi layer. Undoped silicon selective epitaxial growth (SEG) buffered PSC could control gate induced drain leakage (GIDL) to the same level of conventional bulk FinFET. In addition, by optimizing fin height, 25% less word line capacitance (Cwl) was achieved. We place this Pi-FinFET with PSC is one of the promising candidates for the future FinFET DRAM cell technology.
VLSI Technology, 2007 IEEE Symposium on; 07/2007
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ABSTRACT: The crystalline properties of Be substituted ZnO (BeZnO) films deposited on c-Al2O3 substrates are studied. As Be concentration in BeZnO increases, the lattice parameters of BeZnO increases; the c-axis lattice is more sensitively shifted than the a-axis lattice. The energy band gap of the BeZnO films has been efficiently modulated from 3.38 eV to 3.81 eV by adding Be into ZnO. A linear dependency between band gap and lattice parameters is observed from BeZnO films. BeZnO alloys can be used for new ZnO-based devices based on double heterostructures, quantum wells, or superlattices made with ZnO and BeZnO.
Journal of Applied Physics 05/2006; 99(9):096104-096104-3. · 2.17 Impact Factor
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ABSTRACT: A wide-band gap oxide alloy, BeZnO, is proposed and studied in this letter. The BeZnO films were deposited on sapphire substrates by our hybrid beam deposition growth method. The value of the energy band gap of BeZnO can be efficiently engineered to vary from the ZnO band gap (3.4 eV) to that of BeO (10.6 eV). BeZnO can be used for fabricating films and heterostructures of ZnO-based electronic and photonic devices and for other applications. Changes in the measured energy band gap and lattice constant values with Be content are described for BeZnO alloys.
Applied Physics Letters 02/2006; · 3.84 Impact Factor
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ABSTRACT: Studies of pressure induced phase transformations of ZnS nanoparticles using diamond anvil cells and synchrotron radiation were carried out to 20.0 GPa. Nanoparticles initially in the zinc-blende and wurtzite phases both transformed to the NaCl phase under the application of pressure. The zinc-blende particles, which were of 2.8 nm size, and the wurtzite particles, which were of 25.3 nm size, transformed to the NaCl phase at 19.0 and 15.0 GPa, respectively. Nanoparticles of the wurtzite phase never regained their initial wurtzite structure but returned to the zinc-blende phase upon downloading the pressure. The resultant zinc-blende nanoparticles transformed to the NaCl phase upon the reapplication of a pressure of 15.0 GPa. Nanoparticles initially in the zinc-blende phase returned to their original phase. © 2001 American Institute of Physics.
Journal of Applied Physics 12/2000; 89(1):115-119. · 2.17 Impact Factor
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ABSTRACT: Ferroelectric Ba0.4Sr0.6TiO3 (BST) thin films grown on (001) MgO by pulsed laser deposition show a strong correlation between their structure and their microwave dielectric properties. Epitaxially grown BST films are observed by x-ray diffraction to be tetragonally distorted. The oxygen deposition pressure affects the magnitude of the tetragonal distortion (the ratio of in-plane and surface normal lattice parameters, D=a/c) of the deposited BST films. D varied from 0.996 to 1.004 at oxygen deposition pressure of 10–800 mTorr. The dielectric properties of BST films measured at microwave frequencies (1–20 GHz) exhibit an oxygen deposition pressure dependent dielectric constant (ϵ=100–600), and quality factor Q (1/tan δ=10–60). The BST film grown at the oxygen deposition pressure of 200 mTorr exhibits the highest figure of merit [% tuning in ϵ×Q0V, where % tuning is 100×(ϵ0−ϵb)/ϵ0, and ϵ0 and ϵb are dielectric constant at 0 and 80 kV/cm]. This corresponds to the film with the lowest distortion (D=1.001). The observed microwave properties of the films are explained by a phenomenological thermodynamic theory based on the strain along in-plane direction of the films. © 2000 American Institute of Physics.
Journal of Applied Physics 10/2000; 88(9):5448-5451. · 2.17 Impact Factor
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ABSTRACT: Ferroelectric (Ba0.6Sr0.4)TiO3 (BST) thin films have been deposited by pulsed laser deposition onto single-crystal Y3Fe5O12 (YIG) substrates with/without a MgO buffer layer. The structure and microwave properties of the BST films have been investigated as a function of substrate orientation and O2 deposition pressures (50-800 mTorr). The crystallographic orientation of BST film varies with the deposition conditions. The dielectric properties of the ferroelectric were measured using interdigitated capacitors deposited on top of the BST film. BST films exhibit high tunability (20-40%) and high dielectric Q=1/cos' (30-50) with a dc bias field of 67 kV/cm at 10 GHz. A coplanar waveguide transmission line was fabricated from a (001)-oriented BST film on (111)YIG which exhibited a 17 differential phase shift with an applied dc bias field of 21 kV/cm (10 GHz). An equivalent differential phase shift was achieved with a magnetic field of 160 Gauss.
Applied Physics A 06/2000; 71(1):7-10. · 1.63 Impact Factor
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ABSTRACT: A strong correlation is observed between the structure and the microwave dielectric properties of epitaxial Ba <sub> 0.5 </sub> Sr <sub> 0.5 </sub> TiO <sub> 3 </sub> (BST) thin films deposited onto (001) MgO by pulsed laser deposition. Films were deposited at 750 °C in an oxygen pressure that was varied from 3 to 1000 mTorr. The tetragonal distortion (ratio of in-plane and surface normal lattice parameters, D=a/c) of the films depends on the oxygen deposition pressure. D varied from 0.996 at 3 mTorr to 1.003 at 800 mTorr. At microwave frequencies (1–20 GHz), BST films with low distortion have higher dielectric constants (Є∼500), and lower dielectric loss ( tan δ∼0.02) compared to films with higher distortion. The correlation of the microwave properties with the film structure can be attributed to stresses and polarizability in the film. The BST film grown at the oxygen deposition pressure of 50 mTorr exhibits a large dielectric constant change and a low dielectric loss at the same time, which corresponds to the film in low stress (D=1.0004). For tunable microwave applications, BST films with low stress are desirable in order to achieve both low dielectric loss and large tunability. © 2000 American Institute of Physics.
Applied Physics Letters 03/2000; · 3.84 Impact Factor
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ABSTRACT: The relationship between the structure and the microwave dielectric properties of epitaxial Ba0.5Sr0.5TiO3 (BST) films has been investigated. Single-phase BST films (40-160 nm) have been deposited onto (100) MgO substrates by pulsed laser deposition. As-deposited films show a significant tetragonal distortion. The in-plane lattice parameters (a) are always larger than the surface normal lattice parameters (c). The tetragonal distortion depends on the thickness of the films and the post-deposition annealing conditions. Films annealed at 900 C show less tetragonal distortion than the as-deposited film and the films annealed at higher temperatures. The distortion in the film is due to stress caused by the lattice mismatch and thermal expansion coefficient differences between the film and the substrate. The dielectric constant and its change with dc bias voltage of BST films on MgO at microwave frequencies increase with increasing annealing temperature from 900 C to 1200 C, which corresponds to an increase in the tetragonal distortion.
Applied Physics A 02/2000; 70(3):313-316. · 1.63 Impact Factor
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ABSTRACT: This paper presents the feedforward linear power amplifier (LPA)
using error feedback technique to satisfy requirements of personal
communications system (PCS) applications as well as GSM system. The
proposed linear power amplifier is applied to feedforward technique
combined with error feedback technique which has no main signal loss
unlike typical feedback technique. In this case, the ultra reduction of
intermodulation distortions (IMD) can be achieved. To verify ultra
performance of the proposed LPA, it is designed, fabricated and
measured. Two-tone signals at 1.85 GHz and 1.85125 GHz with a dBm/tone
from synthesizers are injected into the LPA. The main power amplifier
with gain of 30 dB and an average power of 10 W was fabricated. The
proposed LPA could reduce more than 35 dB. The total IMD is more than
-70 dBc
Microwave Conference, 2000 Asia-Pacific; 02/2000
