• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.2
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• pp.96-99
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• 2000

The photoluminescened experiments at temperature of 10K were carride out for ZnSe epilayers grown by hot-wall epitaxy. The upper and lower polariton peaks of the neutral dound exciton $I_2$($D^{\circ}$,X) for as-grown epilayer have been dominantly observed.For the heat-treatment under Se ambient,the origin of $I_2$ emission is confirmed to be related to Se-vacancy.The extra neutral acceptor bound exciton $I_1$$^d$ is also observed.The ZnSe epilayer shows the self-compensation effect and it is hard to be converted into p-type ZnSe epilayer.However,the photoluminescence spectrum of the annealed sample in Se ambient shows the intense $I_1$$^d$ emission.This indicates that in the annealed ZnSe epilayer,there are many acceptor levels due to the opical p-type converstion. The binding energy of acceptor-impurity is ecaluated to the value of 268meV and the self-activated emission is disappeared by thermal annealing under Se ambient,which indicates the association with Se-vacancy.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.810-814
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• 2013

The thermodynamic parameters for the intercalative interaction of structurally related well known intercalators, 9-aminoacridine (9AA) and proflavine (PF) were determined by means of fluorescence quenching study. The fluorescence intensity of 9AA decreased upon intercalation to DNA, poly[$d(A-T)_2$] and poly[$d(G-C)_2$]. A van't Hoff plot was constructed from the temperature-dependence of slope of the ratio of the fluorophore in the absence and presence of a quencher molecule with respect to the quencher concentration, which is known as a Stern-Volmer plot. Consequently, the thermodynamic parameters, enthalpy and entropy change, for complex formation was calculated from the slope and y-intercept of the van't Hoff plot. The detailed thermodynamic profile has been elucidated the exothermic nature of complex formation. The complex formation of 9AA with DNA, poly[$d(A-T)_2$] and poly[$d(G-C)_2$] was energetically favorable with a similar negative Gibb's free energy. On the other hand, the entropy change appeared to be unfavorable for 9AA-poly[$d(G-C)_2$] complex formation, which was in contrast to that observed with native DNA and poly[$d(A-T)_2$] cases. The equilibrium constant for the intercalation of PF to poly[$d(G-C)_2$] was larger than that to DNA, and was the largest among sets tested despite the most unfavorable entropy change, which was compensated for by the largest favorable enthalpy. The favorable hydrogen bond contribution to the formation of the complexes was revealed from the analyzed thermodynamic data.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.4
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• pp.45-52
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• 2009

We proposed a new pixel circuit and driving method for the large-area, high-luminance AMOLED applications in this study. We designed with the low-temperature poly-silicon(LTPS) thin film transistors(TFTs) that has poor uniformity but stable characteristic. To improve the uniformity of an image, the threshold voltage($V_{TH}$) and the mobility of the TFTs can be compensated together. The proposed method overcomes the previous methods for mobility compensation, and that is profitable for large-area applications. Black data insertion was introduced to improve the characteristics for moving images. AMOLED panel can operate in two compensation mode, so the luminance degradation by mobility compensation can be released. The scan driver for controlling the pixel circuits were optimized, and the compensation mode can be controlled simply by that. Final driving signal has large timing margin, and the panel operates stably. The pixel circuit was designed for 14.1" WXGA top-emission ANGLED panel. The non-uniformity of the designed panel was estimated under 5% for the mobility compensation time of 1us.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.7
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• pp.637-648
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• 2007

This paper presents a sensor fusion method based on indirect Kalman filter(IKF) for error compensation of low-cost inertial sensors and its application to the determination of attitude and position of small flying robots. First, the analysis of the measurement error characteristics to zero input is performed, focusing on the bias due to the temperature variation, to derive a simple nonlinear bias model of low-cost inertial sensors. Moreover, from the experimental results that the coefficients of this bias model possess non-deterministic (stochastic) uncertainties, the bias of low-cost inertial sensors is characterized as consisting of both deterministic and stochastic bias terms. Then, IKF is derived to improve long term stability dominated by the stochastic bias error, fusing low-cost inertial sensor measurements compensated by the deterministic bias model with non-inertial sensor measurement. In addition, in case of using intermittent non-inertial sensor measurements due to the unreliable data link, the upper and lower bounds of the state estimation error covariance matrix of discrete-time IKF are analyzed by solving stochastic algebraic Riccati equation and it is shown that they are dependant on the throughput of the data link and sampling period. To evaluate the performance of proposed method, experimental results of IKF for the attitude determination of a small flying robot are presented in comparison with that of extended Kaman filter which compensates only deterministic bias error model.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2000.04a
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• pp.43-55
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• 2000

In traditional electronic packages the die and the substrate are interconnected with fine wire. Wire bonding technology is limited to bond pads around the peripheral of the die. As the demand for I/O increases, there will be limitations with wire bonding technology. Flip chip technology eliminates the need for wire bonding by redistributing the bond pads over the entire surface of the die. Instead of wires, the die is attached to the substrate utilizing a direct solder connection. Although several steps and processes are eliminated when utilizing flip chip technology, there are several new problems that must be overcome. The main issue is the mismatch in the coefficient of thermal expansion (CTE) of the silicon die and the substrate. This mismatch will cause premature solder Joint failure. This issue can be compensated for by the use of an underfill material between the die and the substrate. Underfill helps to extend the working life of the device by providing environmental protection and structural integrity. Flux residues may interfere with the flow of underfill encapsulants causing gross solder voids and premature failure of the solder connection. Furthermore, flux residues may chemically react with the underfill polymer causing a change in its mechanical and thermal properties. As flip chip packages decrease in size, cleaning becomes more challenging. While package size continues to decrease, the total number of 1/0 continue to increase. As the I/O increases, the array density of the package increases and as the array density increases, the pitch decreases. If the pitch is decreasing, the standoff is also decreasing. This paper will present the keys to successful flip chip cleaning processes. Process parameters such as time, temperature, solvency, and impingement energy required for successful cleaning will be addressed. Flip chip packages will be cleaned and subjected to JEDEC level 3 testing, followed by accelerated stress testing. The devices will then be analyzed using acoustic microscopy and the results and conclusions reported.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.514-518
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• 2006

We have transferred highly stable 100 MHz RF through a 23 km fiber network. The fiber-induced phase noise due to the vibration and the temperature fluctuation in the optical path is detected and is compensated by configuring a noise-canceling servo. The transfer instability was $6{\times}10^{14}$ at 1 s of averaging time and $2{\times}10^{-17}$ at 10000 s of averaging time. The single sideband phase noise was greatly reduced by more than 20 dB below the Fourier frequency of 1 kHz. The transferred RF has nearly the same stability as the original reference frequency.

• Macromolecular Research
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• v.17 no.6
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• pp.378-387
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• 2009

This research compared three methods for producing and processing nanocomposite polypropylene filament yarns with permanent antimicrobial efficiency. The three methods used to mix antimicrobial agents based on silver nano particles with PP were as follows: 1) mixing of PP powder and inorganic nanocomposite filler with the appropriate concentration using a twin-screw extruder and preparing granules, 2) method 1 with a singlerather than twin-screw extruder, and 3) producing the masterbatch by a twin-screw extruder and blending it with PP in the melt spinning process. All pure polypropylene samples and other combined samples had an acceptable spinnability at the spinning temperature of $240^{\circ}C$ and take-up speed of 2,000 m/min. After producing as-spun filament yarns by a pilot plant, melt spinning machine, the samples were drawn, textured and finally weft knitted. The physical and structural properties (e.g., linear density, tenacity, breaking elongation, initial modulus, rupture work, shrinkage and crystallinity) of the as-spun and drawn yarns with constant and variable draw ratios (the variable draw ratio was used to gain a constant breaking elongation of 50%) were investigated and compared, while DSC, SEM and FTIR techniques were used to characterize the samples. Finally, the antibacterial efficiency of the knitted samples was evaluated. The experimental results revealed that the crystallinity reduction of the as-spun yarn obtained from method 1 (5%) was more than that of method 2 (3%), while the crystallinity of the modified as-spun yarns obtained with method 3 remained unchanged compared to pure yarn. However, the drawing procedure compensated for this difference. By applying methods 2 and 3, the drawing generally improved the tenacity and modulus of the modified fibers, whereas method 1 degraded the constant draw ratio. Although the biostatic efficiency of the nanocomposite yarns was excellent with all three methods, the modified fabrics obtained from methods 1 and 2 showed a higher bioactivity.

• Journal of the Korean Magnetics Society
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• v.11 no.1
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• pp.38-44
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• 2001

The magnetic field standard below 1 mT with the resolution of 0.26 nT has been established. Earth magnetic field (EMF) is compensated automatically down to 0.1 nT/10 min. by a closed feedback system with Cs optical pumping magnetometer and 3-axis Helmholtz coils in nonmagnetic facilities. A multi-layer precision solenoid with the optimized single-current method generates the uniform magnetic field better than 1.0$\times$10$\^$-7/ within $\pm$ 1 cm region at its center. The coil constant of solenoid determined from Helium optical pumping magnetometer is 1.231 058 9 mT/A, and temperature coefficient is 0.38 nT/$\^{C}$. This standard system is used for calibration of low field magnetometers and testing relates to low field.

• Journal of the Korean Magnetics Society
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• v.10 no.5
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• pp.246-249
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• 2000

An Fe$_{49}$ Co$_{49}$ V$_2$alloy is annealed in thermal annealing furnace at 50$0^{\circ}C$, 75$0^{\circ}C$, 80$0^{\circ}C$, and 90$0^{\circ}C$. Annealed samples were cooled in air. The magnetostriction is measured by using a Michelson laser interferometer. Receiving the feedback signal of interference, a mirror attached to piezoelectric transducer (PZT) maintains the optical path length (OPL) between two arms of laser interferometer relatively constant. The feedback voltage is calibrated to the OPL variation. A magnetostriction of 2$\times$10$^{-6}$ at H = 60 Oe increases up to 33.68$\times$10$^{-6}$ at an annealing temperature of 90$0^{\circ}C$, suggesting that the magnetostrictive characteristics are improved by the microstructural modification.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.3 s.18
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• pp.23-28
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• 2005

This study defined engineering mechanism and compensation method to establish reference pressure of smoke control zone with atmospheric pressure that is compensated for temperature. The reliable pressure differential sensor was developed by establishing the specifications, algorithms and constructing engineering data. The development of pressure differential sensor can cut down number of processes, manufacturing and installation cost by removing pressure measurement pipe established separately for non smoke control zone, and improve the accuracy of pressure differential by embedding pressure measurement ports for non smoke control zone. More correct and reliable pressure differentials can be obtained by the central control rather than the existent individual control. This will provide the basics and the flexibility to the integral smoke control system and accordingly improve the performance of disaster prevention.