• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.3
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• pp.241-245
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• 2001

In this paper, we present parameter optimization technique for GaAs/AlGaAs multiple quantum well avalanche photodiodes used for image capture mechanism in high-definition system. Even under flawless environment in semiconductor manufacturing process, random variation in process parameters can bring the fluctuation to device performance. The precise modeling for this variation is thus required for accurate prediction of device performance. The precise modeling for this variation is thus required for accurate prediction of device performance. This paper will first use experimental design and neural networks to model the nonlinear relationship between device process parameters and device performance parameters. The derived model was then put into genetic algorithms to acquire optimized device process parameters. From the optimized technique, we can predict device performance before high-volume manufacturign, and also increase production efficiency.

• Journal of the Korean Society of Visualization
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• v.21 no.3
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• pp.23-32
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• 2023

This study aims to explore the heat transfer and flow phenomena inside an instant water heater and the influence of the design parameters of the water heater on the heating performance was investigated by 3-D numerical simulations considering heat convection. The design parameters are the heating ceramic dimension, the power of the heating device, and the water flow rate. The results show that a reasonable space for the heating device is required to optimize the heating performance. It is desirable to design higher heating device as possible for a given electric power. There exists a critical water flow rate that best meets the heating performance. The change in electric power has no impact on the flow phenomena and heating performance.

• Journal of Ocean Engineering and Technology
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• v.35 no.3
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• pp.216-228
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• 2021

In the present study, the performance of a floating oscillating water column (OWC) device has been studied in regular waves. The OWC model has the shape of a hollow cylinder. The linear potential theory is assumed, and a matched eigenfunction expansion method(MEEM) is applied for solving the diffraction and radiation problems. The radiation problem involves the radiation of waves by the heaving motion of a floating OWC device and the oscillating pressure in the air chamber. The characteristics of the exciting forces, hydrodynamic forces, flow rate, air pressure in the chamber, and heave motion response are investigated with various system parameters, such as the inner radius, draft of an OWC, and turbine constant. The efficiency of a floating OWC device is estimated in connection with the extracted wave power and capture width. Specifically, the piston-mode resonance in an internal fluid region plays an important role in the performance of a floating OWC device, along with the heave motion resonance. The developed prediction tool will help determine the various design parameters affecting the performance of a floating OWC device in waves.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1373-1392
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• 2017

WiFi Direct (WD) is a state of the art technology for a Device-to-Device (D2D) communication in 802.11 networks. The performance of the WD system can be significantly affected by some key factors such as the type of application, specifications of MAC and PHY layer parameters, and surrounding environment etc. It is, therefore, important to develop a system model that takes these factors into account. In this paper, we focus on investigating the design parameters of the PHY layer that could maximize the efficiency of the WD 802.11 system. For this purpose, a basic theoretical model is formulated for a WD network under a 2x2 Multiple In Multiple Out (MIMO) TGn channel B model. The design level parameters such as input symbol rate and antenna spacing, as well as the effects of the environment, are thoroughly examined in terms of path gain, spectral density, outage probability and Packet Error Rate (PER). Thereafter, a novel adaptive algorithm is proposed to choose optimal parameters in accordance with the Quality of Experience (QoE) for a targeted application. The simulation results show that the proposed method outperforms the standard method thereby achieving an optimal performance in an adaptive manner.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.12
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• pp.91-99
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• 1994

We used CMOS current mirror and differenial amplifier to find out how the degradation of each devices in circuit affect total circuit performance. The devices in circuit wer degraded by hot-carrier generated during circuit operation and total circuit performance were changed according to the change of each device parameters. To examine the circuit performance phenomena of current mirror, we analyzed three diffent kinds of current mirrors and made correlation model between circuit performance and stressed device parameters, and compare hot-carrier immunity of these circuits. Also we analyzed how the performance of differential amplifier degraded from the initial value after hot-carrier stress incircuit operations.

• Computers and Concrete
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• v.20 no.4
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• pp.419-427
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• 2017

A methodology, based on fragility functions, is proposed to evaluate the seismic performance of seismic isolated $45^{\circ}$ skewed concrete bridge: 1) twelve types of seismic isolation devices are considered based on two different design parameters 2) fragility functions of a three-span bridge with and without seismic isolation devices are analytically evaluated based on 3D nonlinear incremental dynamic analyses which seismic input consists of 20 selected ground motions. The optimum combinations of isolation device design parameters are identified comparing, for different limit states, the performance of 1) the Seismic Isolated Bridges (SIB) and 2) Not Seismic Isolated Bridge (NSIB) designed according to the AASHTO standards.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1466-1470
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• 2007

MEMS design flow based on DFM concept is presented and applied to gyroscope design as a test case. It is purposed to contribute to the yield improvement by considering the process-related parameters from the design phase. After defining the performance requirements, the sensitivity analysis should be done on the draft design(s) to find out the key parameters related with the device performance. By doing so, TEG can be designed for the selected process and/or material parameters. Through a set of test runs, the process capability is characterized and the material properties are extracted using the TEG. Then we can estimate the virtual yield of the current process for the designed device by running Monte Carlo analysis where the process and/or material property variations are considered. The estimated yield will make us redesign the device to be more robust or improve the current process to have the smaller variations.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.2
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• pp.145-154
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• 2016

In this paper, a pneumatic device for the deployment performance verification of canards deployed by inertia has been designed and the performance of the pneumatic device has been proven through analysis and tests. The pneumatic conveying process, orifice opening process and piston movement process of the pneumatic device were investigated by using numerical methods. The orifice diameter, pressure in a pressure tank and type of gas were regarded as the main design parameters of the pneumatic device. The error rate between analysis and test results under the same conditions was within 4 %. The accuracy of numerical methods used in this study were validated.

• Journal of the Semiconductor & Display Technology
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• v.10 no.4
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• pp.107-112
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• 2011

This paper is for improving the RF frequency performance of a fabricated 100nm ${\Gamma}$-gate MHEMT, scaling down vertically for the epitaxy-structure layers of the device. Hydrodynamic simulation parameters are calibrated for the fabricated MHEMT with the modulation-doped $In_{0.52}Al_{0.48}As/In_{0.53}Ga_{0.47}$As heterostructure grown on the GaAs substrate. With these calibrated parameters, simulations for the vertically-scaled epitaxial layers of the device are performed and analyzed for DC/RF characteristics, including the quantization effect due to the thickness reduction of InGaAs channel layer. A newly designed epitaxy-structure device shows higher extrinsic transconductance, $g_m$ of 1.556 S/mm, and higher frequency performance, $f_T$ of 222.5 GHz and $f_{max}$ of 849.6 GHz.

• Structural Engineering and Mechanics
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• v.86 no.2
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• pp.249-260
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• 2023

The uncertainties involved in structural performances are of importance when the optimum number and property of seismic retrofit devices are determined. This paper proposes a seismic retrofit design framework for asymmetric soft-first-story buildings, considering uncertainties in the soil condition and seismic retrofit device. The effect of the uncertain parameters on the structural performance is used to find a robust and optimal seismic retrofit solution. The framework finds a robust and optimal seismic retrofit solution by finding the optimal locations and mechanical properties of the seismic retrofit device for different realizations of the uncertain parameters. The structural performance for each realization is computed to evaluate the effect of the uncertainty parameters on the seismic performance. The framework utilizes parallel processing to decrease the computationally intensive nonlinear dynamic analysis time. The framework returns a robust design solution that satisfies the given limit state for every realization of the uncertain parameters. The proposed framework is applied to the seismic retrofit design of a five-story asymmetric soft-first-story case study structure retrofitted with a viscoelastic damper. Robust optimal parameters for retrofitting a structure to satisfy the limit state for the different realizations of the uncertain parameter are found using the proposed framework. According to the performance evaluation results of the retrofitted structure, the developed framework is proved effective in the seismic retrofit of the asymmetric structure with inherent uncertainties.