• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.15 no.1
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• pp.21-28
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• 1997

Since beginning of subway construction in 1974, for supplying the demand for increasing urban traffic and solving the traffic jam due to expansion of society and elevation of an individual income, the $1^{st}\;and\;2^{nd}$ construction have been almost done and $3^{rd}$ has been driving forward. However, according to an increment of com-mon usage with the passage of time, structures are superannuated and the amount of improvement and repairs keeps on increasing continuous. And many problems are taking place at underground space because of new constructions for underground facilities such as urban gas, electric power, waterworks, and sewerage. In consequence. The consideration of a counterplan for safety is required deeply This study analyzed problems on maintenance of structure about $1^{st}$ class subway, and will present means that a manage civil structures scientifically and systematically by using GSIS concept that imported into several organizations for facility management recently as making digital graphic elements and historic data into a database rather than using an old method - documents and paper drawings.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.16 no.1
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• pp.100-109
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• 2020

Pipelines subjected to ground movement would be easily exposed to large-scale deformation. Since such deformations may cause the pipeline failure, it is important to ensure the safety of pipelines in various operation conditions. However, crack in weld metal have been considered as one of the main causes that can deteriorate the structural integrity of the pipeline. For this reason, the structural integrity of the pipe containing the crack in the weld should be obtained. In order to assess cracked pipe, J-integral and crack-tip opening displacement(CTOD) have been applied widely as the elastic-plastic fracture mechanics parameters representing crack driving force. In this study, engineering solutions to calculate the J-integral and CTOD of pipes with a circumferential outer surface crack in the weld are proposed. For this purpose, 3-dimensional elastic-plastic finite element(FE) analyses have been performed considering the effect of overmatch and width of weld. The shape of the weld was simplified to I-groove, and axial displacement was employed as for loading condition. Based on FE results, the effects of crack size, material properties and width of weldment on J-integral and CTOD were investigated. Additionally, the J-integral and CTOD for I-groove were compared with those for V-groove to examine the effects of the weld shape, and a proportionality coefficient of J-integral and CTOD was calculated from the results of this paper.

• Journal of the Korean Society for Railway
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• v.16 no.1
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• pp.26-31
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• 2013

The reduction unit is one of the most important components for railway vehicles because the torque of the motor must be transmitted to the wheels of the vehicle by the reduction unit. The faults in the reduction units of high-speed trains are caused by damage such as gear, fatigue. These have serious impacts on safety of the train during operation. To address this development of a system for monitoring, fault diagnosis of the reduction unit is needed to keep the vehicle running safely. Before that can be accomplished, it is most important to understand the vibration characteristics of the reduction unit in a normal state. Vibration diagnosis technology using characteristic-analysis of vibration waveform and frequency is known to be the most effective method for fault diagnosis. In this paper, we analyzed the vibration characteristics of the reduction units two Korean high-speed trains (KTX and KTX II), under normal conditions, by two test methods (driving gear test, full-vehicle test).

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.9
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• pp.43-52
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• 1998

In this paper, a novel type of an integrated controller is designed for vehicles equipped with active classis systems to improve vehicle stability, handling, and ride comfort. The hybrid fuzzy logic controller consists of a fuzzy logic controller, a skyhook controller, an attitude controller, and a roll moment distribution controller, and these controllers are used with a proper combination which is determined by the integrated control logic based on driving conditions of a vehicle. It is shown by simulations using MATRIXx/SYSTEMBBUILD software that ride comfort, handling, and active safety are improved for a 16 degree-of-freedom vehicle dynamic model.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.2
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• pp.11-19
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• 2015

Since CMOS device scaling has stalled, three-dimensional (3-D) integration allows extending Moore's law to ever high density, higher functionality, higher performance, and more diversed materials and devices to be integrated with lower cost. 3-D integration has many benefits such as increased multi-functionality, increased performance, increased data bandwidth, reduced power, small form factor, reduced packaging volume, because it vertically stacks multiple materials, technologies, and functional components such as processor, memory, sensors, logic, analog, and power ICs into one stacked chip. Anticipated applications start with memory, handheld devices, and high-performance computers and especially extend to multifunctional convengence systems such as cloud networking for internet of things, exascale computing for big data server, electrical vehicle system for future automotive, radioactivity safety system, energy harvesting system and, wireless implantable medical system by flexible heterogeneous integrations involving CMOS, MEMS, sensors and photonic circuits. However, heterogeneous integration of different functional devices has many technical challenges owing to various types of size, thickness, and substrate of different functional devices, because they were fabricated by different technologies. This paper describes new 3-D heterogeneous integration technologies of chip self-assembling stacking and 3-D heterogeneous opto-electronics integration, backside TSV fabrication developed by Tohoku University for multifunctional convergence systems. The paper introduce a high speed sensing, highly parallel processing image sensor system comprising a 3-D stacked image sensor with extremely fast signal sensing and processing speed and a 3-D stacked microprocessor with a self-test and self-repair function for autonomous driving assist fabricated by 3-D heterogeneous integration technologies.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.5
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• pp.55-64
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• 2018

In this paper, we propose fully convolutional neural networks based automatic detection of a pothole that directly causes driver's safety accidents and the vehicle damage. First, the training DB is collected through the camera installed in the vehicle while driving on the road, and the model is trained in the form of a semantic segmentation using the fully convolutional neural networks. In order to generate robust performance in a dark environment, we augmented the training DB according to brightness, and finally generated a total of 30,000 training images. In addition, a total of 450 evaluation DB was created to verify the performance of the proposed automatic pothole detection, and a total of four experts evaluated each image. As a result, the proposed pothole detection showed robust performance for missing.

• Wind and Structures
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• v.21 no.2
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• pp.223-239
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• 2015

Open decks are a widely used deck configuration in long-span cable-stayed bridges; however, incorporating aerodynamic countermeasures are advisable to achieve better aerodynamic performance than a bluff body deck alone. A sectional model of an open deck cable-stayed bridge with a main span of 400 m was selected to conduct a series of wind tunnel tests. The influences of five practical aerodynamic countermeasures on flutter and vortex-induced vibration (VIV) performance were investigated and are presented in this paper. The results show that an aerodynamic shape selection procedure can be used to evaluate the flutter stability of decks with respect to different terrain types and structural parameters. In addition, the VIV performance of $\prod$-shaped girders for driving comfortableness and safety requirements were evaluated. Among these aerodynamic countermeasures, apron boards and wind fairings can improve the aerodynamic performance to some extent, while horizontal guide plates with 5% of the total deck width show a significant influence on the flutter stability and VIV. A wind fairing with an angle of $55^{\circ}C$ showed the best overall control effect but led to more lock-in regions of VIV. The combination of vertical stabilisers and airflow-depressing boards was found to be superior to other countermeasures and effectively boosted aerodynamic performance; specifically, vertical stabilisers significantly contribute to improving flutter stability and suppressing vertical VIV, while airflow-depressing boards are helpful in reducing torsional VIV.

• Convergence Security Journal
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• v.16 no.6_2
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• pp.99-107
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• 2016

The purpose of this study is to analyse motor vehicle communication network hacking attacks and to provide its prevention. First, the definition of motor vehicle communication network was provided and types of in-vehicle communication network were discussed. Also, bluetooth hacking attack cases were analysed in order to illustrate dangers of hacking attacks. Based on the analysis, two preventive measures were provided. First, Motor Vehicle Safety Standard Law should be revised. Although the law provides the definition of electronic control system and its standards as well as manufacturing and maintenance for safe driving standards, the law does not have standards for electronic control system hacking prevention and defensive security programs or firmware. Second, to protect motor vehicle communication network, it is necessary to create new laws for motor vehicle communication network protection.

• Aerospace Engineering and Technology
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• v.11 no.2
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• pp.109-116
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• 2012

A vent-relief valve performs as a safety-valve assembly for liquid propellant feeding system of space launch vehicle, which relives pressurant propellant tanks during the filling and the flight. At vent mode, valve is opened and closed by driving pneumatic pressure, and at relief mode, valve is automatically operated to set relief pressure. In this study, we have analyzed a basic layout of vent-relief valve which is designed using foreign LVs(Saturn) to satisfy requirements of Korean Space Launch Vehicle. The simulation model of vent-relief valve is designed by using the AMESim code to verify design parameters and evaluate pneumatic behaviors of valve. In this study, we performed dynamic characteristic simulations on design parameters. And we could predict opening/closing time and pressures, operating performances on design parameters. Using this results, we could suggest detail design and boundary conditions of design.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.263-266
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• 2011

Drivers check always vehicle state for own safety and is necessary to understand about vehicle state. If driver know vehicle state, because driver request vehicle state at vehicle specialty company, driver pay a lot of money and waste a lot of time. Now, drivers have checked vehicle state by using variety features of smart phone due to progress of IT(Information Technology). but existing smartphone vehicle diagnostic system learned professional knowledge of vehicle and know vehicle state. drives not need vehicle diagnostic. to overcome these disadvantages, there use easily drivers by using smartphone and request system to know own all vehicle state. In this paper, there implement vehicle diagnostic system with smartphone based on android OS to use easily this system and know check information of vehicle supplies replacement cycles, vehicle internal problems, Eco driving by using OBD-II data to receive by OBD-II Protocol convert Bluetooth connector.