• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.6
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• pp.132-145
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• 2022

This study was based on the black box images of traffic accidents on highways, cluster analysis and prediction model comparisons were carried out. As analysis data, vehicle driving behavior and road surface conditions that can grasp road and traffic conditions just before the accident were used as explanatory variables. Considering that traffic accident data is affected by many factors, cluster analysis reflecting data heterogeneity is used. Each cluster classified by cluster analysis was divided based on the ratio of the severity level of the accident, and then an accident prediction evaluation was performed. As a result of applying the Logit model, the accident prediction model showed excellent predictive ability when classifying groups by cluster analysis and predicting them rather than analyzing the entire data. It is judged that it is more effective to predict accidents by reflecting the characteristics of accidents by group and the severity of accidents. In addition, it was found that a collision accident during stopping such as a secondary accident and a side collision accident during lane change act as important driving behavior variables.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.6
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• pp.87-96
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• 2022

The traffic vulnerable, including elderly pedestrians, have a relatively low walking speed and slow cognitive response time due to reduced physical ability. Although a smart crossing system has been developed and operated to improve problem, it is difficult to operate a signal that reflects the appropriate walking speed for each pedestrian. In this study, a neural network model and a multiple regression model-based traversing speed estimation model were developed using image information collected in an area with a high percentage of traffic vulnerability. to support the provision of optimal walking signals according to real-time traffic weakness. actual traffic data collected from the urban traffic network of Paju-si, Gyeonggi-do were used. The performance of the model was evaluated through seven selected indicators, including correlation coefficient and mean absolute error. The multiple linear regression model had a correlation coefficient of 0.652 and 0.182; the neural network model had a correlation coefficient of 0.823 and 0.105. The neural network model showed higher predictive power.

• BMB Reports
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• v.40 no.5
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• pp.723-730
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• 2007

Kinesin is an ATP-driven microtubule motor protein that plays important roles in control of microtubule dynamics, intracellular transport, cell division and signal transduction. The kinesin superfamily is composed of numerous members that are classified into 14 subfamilies. Animal kinesins have been well characterized. In contrast, plant kinesins have not yet to be characterized adequately. Here, a novel plant-specific kinesin gene, GhKCH2, has been cloned from cotton (Gossypium hirsutum) fibers and biochemically identified by prokaryotic expression, affinity purification, ATPase activity assay and microtubule-binding analysis. The putative motor domain of GhKCH2, $M_{396-734}$ corresponding to amino acids Q396-N734 was fused with 6$\times$His-tag, soluble-expressed in E. coli and affinity-purified in a large amount. The biochemical analysis demonstrated that the basal ATPase activity of $M_{396-734}$ is not activated by $Ca^{2+}$, but stimulated 30-fold max by microtubules. The enzymatic activation is microtubule-concentration-dependent, and the concentration of microtubules that corresponds to half-maximum activation was about 11 ${\mu}M$, much higher than that of other kinesins reported. The cosedimentation assay indicated that $M_{396-734}$ could bind to microtubules in vitro whenever the nucleotide AMP-PNP is present or absent. As a plant-specific microtubule-dependent kinesin with a lower microtubule-affinity and a nucleotide-independent microtubule-binding ability, cotton GhKCH2 might be involved in the function of microtubules during the deposition of cellulose microfibrils in fibers or the formation of cell wall.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.165-172
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• 2008

The decisive factor for the popularization of telematics services in the future isn the ability to produce advanced service that match the needs of drivers and passengers. The Dedicated Short Range Communication(DSRC)-type of wireless communication system, which is being developed for the Intelligent Transport System(ITS), is one of the broadband wireless systems contributing to the improvement of driver and passenger needs, such as convenience, entertainment, comfort and safety. In this paper, the possibility of applying this system to the traffic information collection service will be explored. Further, a description of the service design for the traffic information collection system using electronic toll collection service will be provided, in the knowledge that the existence of information communication equipment mounted vehicles will remain.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.5
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• pp.615-624
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• 2014

In this paper, we explore the electrical properties and high-frequency performance of carbon nanotube field-effect transistors (CNTFETs), based on the non-equilibrium Green's functions (NEGF) solved self - consistently with Poisson's equations. The calculated results show that CNTFETs exhibit superior performance compared with graphene nanoribbon field-effect transistors (GNRFETs), such as better control ability of the gate on the channel, higher drive current with lower subthreshold leakage current, and lower subthreshold-swing (SS). Due to larger band-structure-limited velocity in CNTFETs, ballistic CNTFETs present better high-frequency performance limit than that of Si MOSFETs. The parameter effects of CNTFETs are also investigated. In addition, to enhance the immunity against short - channel effects (SCE), hetero - material - gate CNTFETs (HMG-CNTFETs) have been proposed, and we present a detailed numerical simulation to analyze the performances of scaling down, and conclude that HMG-CNTFETs can meet the ITRS'10 requirements better than CNTs.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.400.1-400.1
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• 2016

Interfacial engineering approaches as an efficient strategy for improving the power conversion efficiencies (PCEs) of inverted polymer solar cells (iPSCs) has attracted considerable attention. Recently, polymer surface modifiers, such as poly(ethyleneimine) (PEI) and polyethylenimine ethoxylated (PEIE), were introduced to produce low WF electrodes and were reported to have good electron selectivity for inverted polymer solar cells (iPSCs) without an n-type metal oxide layer. To obtain more efficient solar cells, quantum dots (QDs) are used as effective sensitizers across a broad spectral range from visible to near IR. Additionally, they have the ability to efficiently generate multiple excitons from a single photon via a process called carrier multiplication (CM) or multiple exciton generation (MEG). However, in general, it is very difficult to prepare a bilayer structure with an organic layer and a QD interlayer through a solution process, because most solvents can dissolve and destroy the organic layer and QD interlayer. To present a more effective strategy for surpassing the limitations of traditional methods, we studied and fabricated the highly efficient iPSCs with mono-layered QDs as an effective multi-functional layer, to enhance the quantum yield caused by various effects of QDs monolayer. The mono-layered QDs play the multi-functional role as surface modifier, sub-photosensitizer and electron transport layer. Using this effective approach, we achieve the highest conversion efficiency of ~10.3% resulting from improved interfacial properties and efficient charge transfer, which is verified by various analysis tools.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.4
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• pp.418-428
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• 2017

In offshore area, newly deposited Quaternary loose seabed soils are widely distributed. There are a great number of offshore structures has been built on them in the past, or will be built on them in the future due to the fact that there would be no very dense seabed soil foundation could be chosen at planed sites sometimes. However, loosely deposited seabed foundation would bring great risk to the service ability of offshore structures after construction. Currently, the understanding on wave-induced liquefaction mechanism in loose seabed foundation has been greatly improved; however, the recognition on the consolidation characteristics and settlement estimation of loose seabed foundation under offshore structures is still limited. In this study, taking a semi-coupled numerical model FSSI-CAS 2D as the tool, the consolidation and settlement of loosely deposited sandy seabed foundation under an offshore breakwater is investigated. The advanced soil constitutive model Pastor-Zienkiewics Mark III (PZIII) is used to describe the quasi-static behavior of loose sandy seabed soil. The computational results show that PZIII model is capable of being used for settlement estimation problem of loosely deposited sandy seabed foundation. For loose sandy seabed foundation, elastic deformation is the dominant component in consolidation process. It is suggested that general elastic model is acceptable for subsidence estimation of offshore structures on loose seabed foundation; however, Young's modulus E must be dependent on the confining effective stress, rather than a constant in computation.

• Membrane Journal
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• v.27 no.3
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• pp.216-225
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• 2017

Since the experimental proof of one-atom-thick graphene single layer from graphite in 2004, graphene, as a leading material opening two-dimensional world, has been tremendously investigated owing to its intrinsic extraordinary physical properties. Among many promising graphene applications, it is believed that membranes might be one of the first significant applications for graphene and its derivatives (e.g., graphene oxide). Recently, a number of simulation results and proof-of-concept experimental approaches towards graphene membranes reflect such positive prospects. Moreover, graphene and graphene oxide already show many outstanding intrinsic properties suitable for promising membrane platforms, such as the minimum membrane thickness, excellent mechanical strength, high chemical and thermal stability, and the ability to generate nanopores in the two-dimensional, rigid hexagonal lattices or to create slit-like nanochannels between adjacent sheets. In this paper, important theoretical and experimental developments in graphene or graphene oxide-based membranes for gas separation based on intrinsic properties of graphene and its derivatives will be discussed, emphasizing on transport behavior, membrane formation methods, and challenging issues for actual membrane applications.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.62-62
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• 2015

In this study, we study the effects of CF4 plasma treatment on the characteristics of enhancement mode (E-mode) AlGaN/GaN high electron mobility transistors (HEMTs). The CF4 plasma is generated by inductively coupled plasma reactive ion etching (ICP-RIE) system. The CF4 gas is decomposed into fluorine ions by ICP-RIE and then fluorine ions will effect the AlGaN/GaN interface to inhibit the electron transport of two dimension electron gas (2DEG) and increase channel resistance. The CF4 plasma method neither like the recessed type which have to utilize Cl2/BCl3 to etch semiconductor layer nor ion implantation needed high power to implant ions into semiconductor. Both of techniques will cause semiconductor damage. In the experiment, the CF4 treatment time are 0, 50, 100, 150, 200 and 250 seconds. It was found that the devices treated 100 seconds showed best electric performance. In order to prove fluorine ions existing and CF4 plasma treatment not etch epitaxial layer, the secondary ion mass spectrometer confirmed fluorine ions truly existing in the sample which treatment time 100 seconds. Moreover, transmission electron microscopy showed that the sample treated time 100 seconds did not have etch phenomena. Atomic layer deposition is used to grow Al2O3 with thickness 10, 20, 30 and 40 nm. In electrical measurement, the device that deposited 20-nm-thickness Al2O3 showed excellent current ability, the forward saturation current of 210 mA/mm, transconductance (gm) of 44.1 mS/mm and threshold voltage of 2.28 V, ION/IOFF reach to 108. As IV concerning the breakdown voltage measurement, all kinds of samples can reach to 1450 V.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.11
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• pp.718-724
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• 2014

In this work, in order to manufacture the photoelectrode of dye-sensitized solar cells, the different anatase $TiO_2$ paste was prepared by simple route using hydrothermal method. In comparison with the traditional preparing process, the hydrothermally synthesized $TiO_2$ gel was used to make paste directly. Thus, the making process was simplified and the solar conversion efficiency was improved. In comparison with 5.34% solar energy efficiency of HP-1 photoelectrode, the 6.23% efficiency of HDP-1 electrode was improved by 16.67%. This is because hydrothermally synthesized $TiO_2$ gel was used to make paste directly, the dispersibility between $TiO_2$ particles was improved and get the smoother network, leading to the charge transport ability of the electron generated in dye molecular was improved. Further, HDP-2 photoelectrode delivered the best results with Voc (open circuit voltage), Jsc (short circuit current density) FF (fill factor) and ${\eta}$(solar conversion efficiency) were 0.695 V, $15.81mA\;cm^{-2}$, 61.48% and 6.80%, respectively. In comparison with 5.34% of HP-1 photoelectrode, it was improved by 27.34%.