• Korean Journal of Agricultural Science
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• v.43 no.4
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• pp.507-521
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• 2016

Landslides are one of the most common natural hazards causing significant damage and casualties every year. In Korea, the increasing trend in landslide occurrence in recent decades, caused by climate change, has set off an alarm for researchers to find more reliable methods for landslide prediction. Therefore, an accurate landslide-susceptibility assessment is fundamental for preventing landslides and minimizing damages. However, analyzing the stability of a natural slope is not an easy task because it depends on numerous factors such as those related to vegetation, soil properties, soil moisture distribution, the amount and duration of rainfall, earthquakes, etc. A variety of different methods and techniques for evaluating landslide susceptibility have been proposed, but up to now no specific method or technique has been accepted as the standard method because it is very difficult to assess different methods with entirely different intrinsic and extrinsic data. Landslide prediction methods can fall into three categories: empirical, statistical, and physical approaches. This paper reviews previous research and surveys three groups of landslide prediction methods.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.302.1-302.1
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• 2016

Solution-processed amorphous metal-oxide thin-film transistors (TFTs) are considered as promising candidates for the upcoming transparent and flexible electronics due to their transparent property, good performance uniformity and possibility to fabricate at a low-temperature. In addition, solution processing metal oxide TFTs may allow non-vacuum fabrication of flexible electronic which can be more utilizable for easy and low-cost fabrication. Recently, for high-mobility oxide TFTs, multi-layered oxide channel devices have been introduced such as superlattice channel structure and heterojunction structure. However, only a few studies have been mentioned on the bias illumination stress in the multi- layered oxide TFTs. Therefore, in this research, we investigated the effects of bias illumination stress in solution-processed bilayer oxide TFTs which are fabricated by the deep ultraviolet photochemical activation process. For studying the electrical and stability characteristics, we implemented positive bias stress (PBS) and negative bias illumination stress (NBIS). Also, we studied the electrical properties such as field-effect mobility, threshold voltage ($V_T$) and subthreshold slop (SS) to understand effects of the bilayer channel structure.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.103-109
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• 2013

Mobile ad hoc networks (MANETs) are infrastructure-less and stand-alone wireless networks with dynamic topologies. To support user's safety in MANETs, fundamental and various security services should be supported. Especially in mobile commercial market, one of the major concerns regarding security is user privacy. Recently, researches about security system to protect user privacy in cluster-based MANETs have been introduced. This paper propose a cluster reconfiguration protocol under anonymous cluster-based MANETs to enhance the network stability. The improved anonymous cluster-based MANETs can recover the network structure against abnormal states of clutserheads.

• Tunnel and Underground Space
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• v.6 no.2
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• pp.101-121
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• 1996

The thermomechanical characteristics of rocks such as temperature dependency of strength and deformation were experimentally investigated using Iksan granite, Cheonan tonalite and Chung-ju dolomite for proper design and stability analysis of underground structures subjected to temperature changes. For the temperature below critical threshold temperature $T_c$, the variation of uniaxial compressive strength, Young's modulus, Brazilian tensile strength and cohesion with temperature were slightly different for each rock type, but these mechanical properties decreased at the temperatures above $T_c$ by the effect of thermal cracking. Tensile strength was most affected by $T_c$, and uniaxial compressive strength was least affected by $T_c$. To the temperature of 20$0^{\circ}C$ with the confining prressure to 150 kg/$\textrm{cm}^2$, failure limit on principal stress plane and failure envelope on $\sigma$-$\tau$ plane of Iksan granite were continuously lowered with increasing temperature but those of Cheonan tonalite and Chung-ju dolomite showed different characteristics depending on minor principal stress on principal stress plane and normal stress on $\sigma$-$\tau$ plane. The reason for this appeared to be the effect of rock characteristics and confining pressure. Young's modulus was also temperature and pressure dependent, but the variation of Young's modulus was about 10%, which was small compared to the variation of compressive strength. In general, Young's modulus increased with increasing confining pressure and increased or decreased with increasing temperature to 20$0^{\circ}C$ depending on the rock type.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.6
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• pp.428-435
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• 1998

SOI-like-bulk CMOS device is proposed, which having the advantages of SOI(Silicon On Insulator) and protects short channel effects efficiently with adding partial epitaxial process at standard CMOS process. SOI-like-bulk NMOS and PMOS with 0.25${\mu}{\textrm}{m}$ gate length have designed and optimized through analyzing the characteristics of these devices and applying again to the design of processes. The threshold voltages of the designed NMOS and PMOS are 0.3[V], -0.35[V] respectively and those have shown the stable characteristics under 1.5[V] gate and drain voltages. The leakage current of typical bulk-CMOS increase with shortening the channel length, but the proposed structures on this a study reduce the leakage current and improve the subthreshold characteristics at the same time. In addition, subthreshold swing value, S is 70.91[mV/decade] in SOI-like-bulk NMOS and 63.37[mV/ decade] SOI-like-bulk PMOS. And the characteristics of SOI-like-bulk CMOS are better than those of standard bulk CMOS. To validate the circuit application, CMOS inverter circuit has designed and transient & DC transfer characteristics are analyzed with mixed mode simulation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1441-1461
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• 2017

Nowadays, Dynamic Adaptive Streaming over HTTP (DASH) has become very popular in streaming multimedia contents. In DASH, a client estimates current network bandwidth and then determines an appropriate video quality with bitrate matching the estimated bandwidth. Thus, estimating accurately the available bandwidth is a significant premise in the quality of video streaming, especially when network traffic fluctuates substantially. To cope with this challenge, researchers have presented various filters to estimate network bandwidth adaptively. However, experiment results show that current schemes either adapt slowly to network changes or adapt fast but are very sensitive to delay jitter and produce sharply changed estimation. This paper presents a novel bandwidth estimation scheme based on Moving Average Convergence Divergence (MACD). We applied an MACD indicator and its two thresholds to classifying network states into stable state and agile state, based on the network state different filters are applied to estimate network bandwidth. In the paper, we studied the performance of various MACD indicators and the threshold values on bandwidth estimation. Then we used a DASH proxy-based environment to compare the performance of the presented scheme with current well-known schemes. The simulation results illustrate that the MACD-based bandwidth estimation scheme performs superior to existing schemes both in the speed of adaptively to network changes and in stability in bandwidth estimation.

• Carbon letters
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• v.15 no.3
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• pp.214-217
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• 2014

A filtration-taping method was demonstrated to fabricate carbon nanotube (CNT) emitters. This method shows many good features, including high mechanical adhesion, good electrical contact, low temperature, organic-free, low cost, large size, and suitability for various CNT materials and substrates. These good features promise an advanced field emission performance with a turn-on field of $0.88V/{\mu}m$ at a current density of $0.1{\mu}A/cm^2$, a threshold field of $1.98V/{\mu}m$ at a current density of $1mA/cm^2$, and a good stability of over 20 h. The filtration-taping technique is an effective way to realize low-cost, large-size, and high-performance CNT emitters.

• Journal of Photoscience
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• v.8 no.3_4
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• pp.113-117
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• 2001

Several styrylquinolium salts were synthesized to investigate their absorption and thermal properties, which had five different p-aminobenzene units and three different counter ions (iodide, perchlorate, and hexafluorophosphorate anion), respectively. Hydroxy, methoxy, and methyl group in the meta position to the amino group led to bathochromic shift, while Ν-ethyl-Ν-chloroethylamino unit instead of Ν,Ν-diethylamino unit resulted in hypsochromic shift. A dye having a methoxy group in the meta position to the amino group had the highest molar extinction coefficient ($\xi$), while a dye carrying chloro group in Ν-alkyl chains had the lowest $\xi$. The type of counter ions had no effect on spectral properties like the maximum absorption wavelength and $\xi$. All styryl dyes had exothermic peaks at decomposition in DSC curves. Among these styryl dyes, S2 series with perchlorate anions showed the strongest exothermic decomposition. From TGA spectra, S3 series with hexafluorophosphorate anions had the best thermal stability and the sharpest threshold at thermal decomposition.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.18
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• pp.7775-7780
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• 2014

This paper addresses cancer prediction based on radial basis function neural network optimized by particle swarm optimization. Today, cancer hazard to people is increasing, and it is often difficult to cure cancer. The occurrence of cancer can be predicted by the method of the computer so that people can take timely and effective measures to prevent the occurrence of cancer. In this paper, the occurrence of cancer is predicted by the means of Radial Basis Function Neural Network Optimized by Particle Swarm Optimization. The neural network parameters to be optimized include the weight vector between network hidden layer and output layer, and the threshold of output layer neurons. The experimental data were obtained from the Wisconsin breast cancer database. A total of 12 experiments were done by setting 12 different sets of experimental result reliability. The findings show that the method can improve the accuracy, reliability and stability of cancer prediction greatly and effectively.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.12
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• pp.63-69
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• 1999

Center of photon mass, defined as the center of axial photon distribution in each half, is proposed as a unified design parameter in quarter wavelength shifted(QWS) DFB lasers. Shown is the way the parameter is related to the threshold pain difference and uniformity in axial photon density, which determine single-frequency stability of DFB lasers. Also, a general rule for single-frequency DFB laser design is presented. Using the design rule, we propose a sampled grating QWS-DFB laser that has a wider $_KL$ range 0f 100% single-frequency yield.