• Tunnel and Underground Space
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• v.23 no.2
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• pp.87-98
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• 2013

Around 70% of Korea is mountainous, an increase in tunnel construction. It's due to the growing interest of the public for the environment and land required for the road construction is very scarce. During construction of 'Daedong 1 tunnel' in the expressway expansion project between Naengjeong and Busan, there are shallow shaft due to this tunnel located in the valley and the shafts are separated, and penetrating location change was inevitable for construction was delayed because of complaint. So, we change the position of the penetrating by applying multi-channel TSP, and conducted a stability analysis. The analysis results showed that there is no problem on the stability of the tunnel. To secure the construction of additional stability, We installed instrument, performed mechanical excavation, added reinforcement at shallow shaft and conducted bench cut.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.55-55
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• 2018

Recently, amorphous oxides such as InGaZnO (IGZO) and InZnO (IZO) as a channel layer of an oxide TFT have been attracted by advantages such as high mobility, good uniformity, and high transparency. In order to apply such an amorphous oxide TFTs to a display, the stability in various environments must be ensured. In the InGaZnO which has been studied in the past, Ga elements act as a suppressor of oxygen vacancy and result in a decreased mobility at the same time. Previous studies have been showed that the InZnO, which does not contain Ga, can achieve high mobility, but has relatively poor stability under various instability environments. In this study, the TFTs using $IZO/Al_2O_3$ double layer structure were studied. The introduction of an $Al_2O_3$ interlayer between source/drain and channel causes superior electrical characteristics and electrical stability as well as reduced contact resistance with optimally perfect ohmic contact. For the IZO and $Al_2O_3$ bilayer structures, the IZO 30nm IZO channels were prepared at $Ar:O_2=30:1$ by sputtering and the $Al_2O_3$ interlayer were depostied with various thickness by ALD at $150^{\circ}C$. The optimal sample exhibits considerably good TFT performance with $V_{th}$ of -3.3V and field effect mobility of $19.25cm^2/Vs$, and reduced $V_{th}$ shift under positive bias stress stability, compared to conventional IZO TFT. The enhanced TFT performances are closely related to the nice ohmic contact properties coming from the defect passivation of the IZO surface inducing charge traps, and we will provide the detail mechanism and model via electrical analysis and transmission line method.

• Nuclear Engineering and Technology
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• v.27 no.3
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• pp.358-373
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• 1995

The Heat Transport system loop stability of CANDU-6 reactor using the CANFLEX fuel bundle was studied. The Thermal-hydraulic behavior of CANFLEX fuel bundle is similar to the conventional 37-element fuel bundle since the reactor power and the frictional pressure drop through the fuel channel is almost the same each other, Mounter the CANFLEX fuel bundle gives higher critical channel power and more homogeneous enthalpy distributions in the subchannels than 37-element fuel bundle. The SOPHT modelling or the CANFLEX fuel bundle and the Reactor outlet Header(ROH) interconnection line was made and the stability analysis response of Wolsong-1 reactor with CANFLEX fuel bundle was obtained. Without the ROH interconnection line the Heat Transport system loop using 43-element fuel bundle is unstable like the current 37-element fuel bundle. With the ROH interconnection line, however, the Heat Transport system is stable within $\pm$1％ of nominal flow. In the Heat Transport system loop stability point of view for Wolsong-1 plant therefore, the CANFLEX fuel loading is considered to be acceptable.

• Transactions of Materials Processing
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• v.15 no.5 s.86
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• pp.360-365
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• 2006

Carbon nanotubes (CNTs) have been the subject of intensive studies for applications in the fields of nano technologies in recent years due to their superior mechanical, electric, optical and electronic properties. Because of their exceptionally small diameters (${\appros}\;several\;nm$) as well as their high Young's modulus (${\appros}1\;TPa$), tensile strength (${\appros}\;200\;GPa$) and high elongation (10-30%) in addition to a high chemical stability, CNTs are attractive reinforcement materials for light weight and high strength metal matrix composites. Although extensive researches have been performed on the electrical, mechanical and functional properties of CNTs, there are not many successful results on the mechanical properties of CNT dispersed nanocomposites. In this paper, we applied equal channel angular pressing for consolidation of CNT/Cu powder mixtures. We also investigated the hardness and microstructures of CNT/Cu nanocomposites used experimental for metal matrix composites.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1864-1876
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• 2015

In this paper, we propose a singular perturbation-like approach to EDFA gain controller design and analysis. Considering a three-level model of EDFA, a gain controller containing a state observer and a channel add/drop estimator is designed based on a singular perturbation - like concept. The proposed design methodology is shown to be effective and advantageous not only in theoretically verifying the asymptotic stability of systems with multi-time scales such as EDFA but also in designing an asymptotic estimator for channel add/drops which does not satisfy the matching condition.

• Journal of information and communication convergence engineering
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• v.5 no.4
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• pp.333-338
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• 2007

In this paper we propose a new structure of the long code MMSE receiver with pilot channel, which maintians excellent symbol detection capability even in the presence of Rayleigh fading. We explain analytically how the stability of the receiver weight vector, which is critical to the system performance, can be achieved by compensating the error signal as well as received signal vector distorted by fading channel. Computer simulation shows while maintaining better performance than the conventional matched filter receiver, the proposed long code MMSE receiver can extend its period up to $16{\times}T_b$ in a fading environment.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.12
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• pp.969-976
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• 2003

A remote control strategy for vehicles in Intelligent Vehicle Highway System (IVHS) is considered. An optimal scheduling of a limited communication channel is proposed for lead vehicle control in a platoon. The optimal scheduling problem is to find the optimal communication sequence that minimizes the cost obtained inherently by an optimal control without the communication constraint. In this paper, the PID control law which guarantees the string stability is used for the lead vehicle control. The fact that the PID control law is equivalent to the approximately linear quadratic tracker allows to obtain the performance measure to find an optimal sequence. Simulations are conducted with five maneuvering platoons to evaluate the optimality of the obtained sequence.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.11
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• pp.1671-1675
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• 2012

In this paper, we fabricate multi-channel receiver for radar system. This receiver at X-band can be received 8 signal of an identical characteristic, dynamic range has more than 80[dB]. To process direct received signals, this system has the built-in two digital de-modulators which offer the minimum loss on the receiving signal path and has high stability by adding Built-In Test. The gain, noise figure, difference of amplitude and phase on the signal path is respectively $14{\pm}2$[dB], 19[dB], ${\pm}2$[dB], $10^{\circ}$ and below.

• Journal of the Korean Society of Visualization
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• v.2 no.1
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• pp.46-51
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• 2004

This paper deals with the evaluation of several boundary conditions which are commonly used in the lattice Boltzmann equation method. 2-D channel flow(Poiseuille flow) and lid-driven cavity flow was selected as a test problem of this study, because there exist an analytic solution and previous study which could be used for a benchmarking test. It was found that lattice Boltzmann method still needs more considerations of stability and physical consistency, though it could predict the flow patterns both qualitatively and quantitatively.

• Transactions on Electrical and Electronic Materials
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• v.18 no.3
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• pp.141-143
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• 2017

Novel structured thin film transistors (TFTs) of amorphous silicon zinc tin oxide (a-SZTO) were designed and fabricated with a thin metal layer between the source and drain electrodes. A SZTO channel was annealed at $500^{\circ}C$. A Ti/Au electrode was used on the SZTO channel. Metals are deposited between the source and drain in this novel structured TFTs. The mobility of the was improved from $14.77cm^2/Vs$ to $35.59cm^2/Vs$ simply by adopting the novel structure without changing any other processing parameters, such as annealing condition, sputtering power or processing pressure. In addition, stability was improved under the positive bias thermal stress and negative bias thermal stress applied to the novel structured TFTs. Finally, this novel structured TFT was observed to be less affected by back-channel effect.