• Journal of the Institute of Electronics Engineers of Korea SD
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• 제41권11호
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• pp.7-13
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• 2004

Experimental results are presented for the degradation of 3 nm-thick gate oxide under -2.5V $\leq$ V$_{g}$ $\leq$-4.0V stress and 10$0^{\circ}C$ conditions using P and NMOSFETs that are annealed with hydrogen or deuterium gas at high-pressure (5 atm). The degradation mechanisms are highly dependent on stress conditions. For low gate voltage, hole-trapping is found to dominate the reliability of gate oxide both in P and NMOSFETs. With increasing gate voltage to V$_{g}$ =-4.0V, the degradation becomes dominated by electron-trapping in NMOSFETs, however, the generation rate of "hot" hole was very low, because most of tunneling electrons experienced the phonon scattering before impact ionization at the Si interface. Statistical parameter variations as well as the gate leakage current depend on and are improved by high-pressure deuterium annealing, compared to corresponding hydrogen annealing. We therefore suggest that deuterium is effective in suppressing the generation of traps within the gate oxide. Our results therefore prove that hydrogen related processes are at the origin of the investigated oxide degradation.gradation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• 제51권3호
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• pp.295-301
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• 2015

Target strength (TS) information is an important parameter that estimates the detection, distribution, and abundance of Aurelia aurita. In order to investigate the biological TS of jellyfish, some factors such as size (bell diameter), tilt angle, pulsation, and symbion should be known. In the ex situ TS measurements, the tilt angles and pulsation from synchronized swimming behavior of four live A. aurita (bell diameters in the air: 54.2 ~ 94.2 mm) were measured with the acoustic data at 70 kHz. The reduced target strength (RTS) of A. aurita was found to change ranged from 13.4 ~ 16.5 dB according to the incidence angles from $-30^{\circ}$ to $24^{\circ}$. When the change rate of bell diameter in the water was 0.2, the TS value showed a 7.2 dB change. These results could be utilized as an important data to understand the acoustic characteristic scattering of A. aurita.

• Transactions of the Korean Society of Mechanical Engineers B
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• 제28권12호
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• pp.1557-1566
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• 2004

A flame extinction phenomenon is a typical unsteady process in combustion. Flame extinction is characterized by various physical phenomena, such as convection, diffusion, and the production of heat and mass. Flame extinction can be achieved by either increasing the strain rate or curvature, by diluting an inert gas or inhibitor, or by increasing the thermal or radiant energy loss. Though the extinction is an inherently transient process, steady and quasi-steady approaches have been used as useful tools for understanding the flame extinction phenomenon. Recently, unsteady characteristics of flames have been studied by many researchers, and various attempts have been made to understand unsteady flame behavior, by using various extinction processes. Representative parameters for describing flame, such as flame temperature, important species related to reactions, and chemi-luminescence of the flame have been used as criterions of flame extinction. In these works, verification of each parameter and establishing the proper criterions of the extinction has been very important. In this study, a time-dependent flame temperature and an OH radical concentration were measured using optical methods, and the instantaneous change of the flame luminosity was also measured using a high-speed ICCD (HICCD) camera. We compare the unsteady extinction points obtained by three different methods, and we discuss transient characteristics of maximum flame temperature and OH radical distribution near the extinction limit.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.253-253
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• 2012

The effects of oxidation on the order-disorder transition in NiPt bimetallic alloy crystal have been investigated using in-situ synchrotron x-ray scattering technique. The temperature dependence of the crystal structure and the order parameter were measured during in-situ heating and cooling under vacuum and oxygen environments. The order-disorder transition temperature of NiPt alloy crystals in vacuum was between $615^{\circ}C$ and $627^{\circ}C$. On the other hand under oxygen environment, the transition temperature decreases by about $31^{\circ}C$ after the oxidation. The change of the transition temperature can be explained by the formation of NiO crust on the surface of NiPt crystal, which alters the composition of the Ni and Pt atoms. Since the transition temperature depends sensitively on the Ni-Pt composition, the transition temperature changes as Ni atoms diffuse out to form NiO.

• Economic and Environmental Geology
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• 제33권4호
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• pp.295-307
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• 2000

Probabilistic analysis is a powerful method to quantify variability and uncertainty common in engineering geology fields. In rock slope engineering, the uncertainty and variation may be in the form of scatter in orientations and geometries of discontinuities, and also test results. However, in the deterministic analysis, the factor of safety which is used to ensure stability of rock slopes, is based on the fixed representative values for each parameter without a consideration of the scattering in data. For comparison, in the probabilistic analysis, these discontinuity parameters are considered as random variables, and therefore, the reliability and probability theories are utilized to evaluate the possibility of slope failure. Therefore, in the probabilistic analysis, the factor of safety is considered as a random variable and replaced by the probability of failure to measure the level of slope stability. In this study, the stochastic properties of discontinuity parameters are evaluated and the stability of rock slope is analyzed based on the random properties of discontinuity parameters. Then, the results between the deterministic analysis and the probabilistic analysis are compared and the differences between the two analysis methods are explained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제15권2호
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• pp.121-126
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• 2004

This paper presents an SAR-data calibration technique using a well-calibrated scatterometer. At first a fully-polarimetric antenna pattern(magnitude and phase) of the antenna main-beam using a conducting sphere was measured. Then, this data were used to calibrate polarimetrically an auto-mounted network analyzer-based scatterometer system. This scatterometer system can be used to measure the accurate Mueller matrices of earth surfaces such as grass fields, rice fields and bare soil surfaces; i.e., the phase-difference parameters can be obtained as well as the radar scattering coefficients. If a polarimetrically calibrated scatterometer is operated at the same time with the SAR system, the scatterometer data can be used to correct the SAR data, especially the phase-difference parameters. It was found that the correction effect is remarkable for the degree of correlation ${\alpha}$, which is one of the phase-difference parameter, while the correction effect is negligible for the magnitude parameters(backscattering coefficients).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제10권5호
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• pp.694-700
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• 1999

In this paper, we studied the design of power divider using the slow-wave effect of Photonic Bandgap structure, which is etched on the ground plane. The proposed PBG structure can provides the changing of the characteristic impedance of the transmission line and the group delay velocity characteristic. Therefore we can make wider width than the width of conventional transmission line and decrease the length of transmission line. We presented the application for power divider using the characteristic impedance and electrical length extracted from scattering parameter. As adding proposed defect units, the effect of defect is studied. The experimental results show good agreements with the simulated results.

• Composites Research
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• 제12권2호
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• pp.53-61
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• 1999

A failure criterion must be considered in each failure mode and loading condition to provide easy determining strength parameters, flexibility and rational simplicity. In this study, new failure criterion was developed by introducing equivalent strength under biaxial loading of tension and torsion. The experimental results showed that the equivalent biaxial strength has a power law relation with respect to a parameter, cos($tan^{-1}R_b$). Failure strength under biaxial loadings could be predicted as a function of tensile strength, torsional strength and biaxial ratio. The scattering of experimental data could be predicted using a Weibull distribution function and the concept of equivalent biaxial strength. Also, in this study, a fatigue theory was developed based on a plane stress model which enabled the S-N curve for combined stress states to be predicted from the S-N data for uniaxial loading. The prediction models can be predicted a biaxial strength and fatigue life of general laminated composite naterials under multi-axial loadings.

• Journal of the Korean Vacuum Society
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• 제7권4호
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• pp.355-360
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• 1998

Epitaxial $Ba_{0.5}Sr_{0.5}TiO_3$thin films of two different thickness (~250 $\AA$ and ~1340 $\AA$) on MgO(001) prepared by a pulsed laser deposition method were studied by synchroton x-ray scattering measurements. The film initially grew on MgO(001) with a cube-on-cube relationship, maintaining it during further growth. As the film grew, the surface of the film became rough significantly, but the interface between the film and the substrate seemed to have changed little. In the early stage, the film was highly strained in a tetragonal structure with the longer axis parallel to the surface normal direction. As the growth proceeded further, it was mostly relaxed to a cubic structure with the lattice parameter of the bulk value and the mosaic distribution improved significantly in both in-plane and out-of-plane directions.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제23권4호
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• pp.416-422
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• 2019

This paper proposes a GPU-based modeling and rendering of 3D clouds using procedural functions. The formation of clouds is based on modified noise function made with fbm(Fractional Brownian Motion). Those noise values turn into densities of droplets of liquid water, which is a critical parameter for forming the three different types of clouds. At the rendering stage, the algorithm applies the ray marching technique to decide the colors of cloud using density values obtained from the noise function. In this process, all lighting attenuation and scattering are calculated by physically based manner. Once we have the clouds, they are blended on the sky, which is also rendered physically. We also make the clouds moving in the sky by the wind force. All algorithms are implemented and tested on GPU using GLSL.