• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.1
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• pp.47-52
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• 2012

A power amplifier is one of important factors for basestation's efficiency and the researches for efficency enhancement focus Doherty amplifier structure with GaN power devices in these days. A memory effect of Doherty amplifier affect operation characteristics for linearity and efficiency. This paper reports on electrothermal nonlinearity modeling and compensation for GaN Doherty amplifier's distortion. Also this paper reports on the dynamic expression of the instantaneous junction temperature as a function of the instantaneous dissipated power. We design distortion model for GaN Doherty amplifier and predistortion compensator for electrothermal memory effect from the proposed behavior model parameters. The simulations was evaluated by ADS Tools and GaN Doherty amplifier with 37dBm. The GaN Doherty amplifier with compensator enhanced about 16dB than without electrothemal memory effect compensator in 2-tone output spectrum.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.3
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• pp.458-464
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• 2017

A magnetic tunnel junction (MTJ) based ternary content addressable memory (TCAM) is proposed which provides non-volatility. A unit cell of the TCAM has two MTJ's and 4.875 transistors, which allows the realization of TCAM in a small area. The equivalent resistance of parallel connected multiple unit cells is compared with the equivalent resistance of parallel connected multiple reference resistance, which provides the averaging effect of the variations of device characteristics. This averaging effect renders the proposed TCAM to be variation-tolerant. Using 65-nm CMOS model parameters, the operation of the proposed TCAM has been evaluated including the Monte-Carlo simulated variations of the device characteristics, the supply voltage variation, and the temperature variation. With the tunneling magnetoresistance ratio (TMR) of 1.5 and all the variations being included, the error probability of the search operation is found to be smaller than 0.033-%.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.281-284
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• 2004

Photo-induced memory effect of an organic light-emitting diode(OLED) composed of a hydrazone-derivative(DBAH) dispersed in bis-phenol-A type polycarbonate polymer(PCA) in the presence of thio-Michler's ketone, was investigated by the measuring of the current density and luminance at the various conditions. After the light exposure, the current of the OLED was decreased approximately one order, and the luminance of the OLED also decresed. This memory effct was erasable by heating the OLED to the temperature higher than the glass transition temperature(Tg). As shown in this result, we found the memory effect was erased by heating and returned to its original state in the hole injecting layer(HIL) of the OLED. A series of these phenomena was suggested the possibility of the application to the imaging plate.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.5
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• pp.42-46
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• 1999

The strengthening of a metal matrix composite(MMC) by the shape memory effect(SME) of dispersed TiNi particles was theoretically studied. An analytical model was constructed for the prediction of the average residual stress(<$\delta$>m) on the base of the Eshelby's equivalent inclusion method. The analysis was performed on the TiNi particle/Al metal matrix composites with varying volume fractions and prestrains of the particle. The residual stress caused by the shape memory of predeformed fillers has been predicted to contribute significantly to the strengthening of this composite.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.687-691
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• 2001

Al alloy matrix composite with TiNi shape memory fiber as reinforcement has been fabricated by hot pressing to investigate mechanical properties. The stress-strain behavior of the composites was evaluated at temperatures between 363K and room temperature as a function of pre-strain by using experimental and finite element analysis, and both cases showed that the tensile stress at 363K was higher than that of the room temperature. Especially, the tensile stress of this composite increases with increasing the amount of pre-strain, and it also depends on the volume fraction of fiber and heat treatment. The smartness of the composite is given due to the shape memory effect of the TiNi fiber which generates compressive residual stress in the matrix material when heated after being pre-strained.

• Journal of the Semiconductor & Display Technology
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• v.14 no.2
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• pp.41-45
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• 2015

From 20nm technology node, the finFET has become standard device for ULSI's. However, the finFET process made stacking gate non-volatile memory obsolete. Some reported capacitor-less DRAM structure by utilizing the FBE. We present possible non-volatile memory device structure similar to the dual gate MOSFET. One of the gates is left floating. Since body of the finFET is only 40nm thick, control gate bias can make electron tunneling through the floating gate oxide which sits across the body. For programming, gate is biased to accumulation mode with few volts. Simulation results show that the programming electron current flows at the interface between floating gate oxide and the body. It also shows that the magnitude of the programming current can be easily controlled by the drain voltage. Injected electrons at the floating gate act similar to the body bias which changes the threshold voltage of the device.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.12
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• pp.1153-1160
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• 2008

In this paper, the algorithm of Abaqus UMAT is introduced to analyze the shape memory alloy. The SMA has two main effects which show non-linearity. Due to this, it is hard to analyze SMA using analysis tools and to describe all of two effects. Therefore, in this study, the program using Abaqus UMAT based on Modified Brinson model is used to analyze SMA. The martensite fraction, the most important factor which defines SMA motion, is also calculated by Fortran program in UMAT. In addition, the tensile test of SMA specimen is conducted. The availability of algorithm is proved by comparing analysis to experimental result.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.403-405
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• 2000

This paper describes a single transistor type ferroelectric field effect transistor (1Tr FeFET) memory cell scheme, which select one unit memory cell and program/read it. The well voltage can be controlled by isolating the common row well lines. Through applying bias voltage to Gate and Well, respectively, we implement If FeFET memory cell scheme in which interference problem is not generated and the selection of each memory cell is possible. The results of HSPICE simulations showed the successful operations of the proposed cell scheme.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.147-152
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• 1999

The strengthening of a metal matrix composite(MMC) by the shape memory effect(SME) of dispersed TiNi particles was theoretically studied. An analytical model was constructed for the prediction of the average residual stress(<$\sigma$>/sub/m) on the base of the Eshelby's equivalent inclusion method. The analysis was performed on the TiNi particle/Al metal matrix composites with varying volume fractions and prestrains of the particle. The residual stress caused by the shape memory of predeformed fillers has been predicted to contribute significantly to the strengthening of this composite.

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.424-429
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• 1996

Thin films of Ti-Ni alloy were formed by sputtering under various Ar gas pressures and r. f. powers to investigate the optimum sputtering conditions and to demonstrate their shape memory effect. The composition and structure of the films were examined by electron micro-probe analysis and scanning electron microscope. These films were annealed in order to crystallize them. The mechanical property of the annealed films was evaluated by a conventional bending test. The transformation tmeperatures were determined by differential scanning calorimetry. The shape memory behaviour was examined quantiatatively by changing in sample temperature under various constant loads. It was found that the Ar gas pressure had a critical effect on the mechanical property of the thin film,s although the r.f. power also affected it. The films formed at a high Ar gas pressure were too brittle to be bent successfully. However, the films formed at a low Ar gas pressur could be bent and their shape memory behavior was found to be comparable with that of bulk Ti-Ni alloys.