• Journal of the Korea Society of Computer and Information
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• v.19 no.7
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• pp.95-102
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• 2014

There are a variety of structures below the surface are buried. In particular, if It is experiencing problems in the city gas pipe or electrical wire, our safety would be greatly jeopardized. Therefore, the underground structures which encounter a variety of pollutants are highly sensitive to corrosion. So if you are not identify the degree of corrosion, it can lead to large accidents such as gas leakage. Until now, person visit directly every underground structure to measure and record manually, but This approach requires a lot of human and material resources and the continuity of management. Therefore, the research to find out the risk factors quickly via the continuous management is needed, and in this paper the structures management systems in the vehicle being moved by combining ICT underground structures for state information wirelessly collects and analyzes system is proposed.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.2
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• pp.23-29
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• 2014

The advanced traffic management system of intelligent transport systems automates the related traffic tasks such as vehicle speed, traffic volume and traffic incidents through the improved infrastructures like high definition cameras, high-performance radar sensors. For the safety of road users, especially, the automated incident detection and secondary accident prevention system is required. Normally, CCTV based image object detection and radar based object detection is used in this system. In this paper, we proposed the algorithm for real time highway incident detection system using multi surveillance cameras to mosaic video and track accurately the moving object that taken from different angles by background modeling. We confirmed through experiments that the video detection can supplement the short-range shaded area and the long-range detection limit of radar. In addition, the video detection has better classification features in daytime detection excluding the bad weather condition.

• 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 electronic communication sciences
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• v.7 no.3
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• pp.499-505
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• 2012

TPMS(Tire Pressure Monitoring System) using the wireless communication technique is defined as the safety aid system to efficiently realize and manage the condition of tires in the vehicle. The wireless communication system of TPMS should suffers from various noise and interferences such as signals of each tire sensor or outside electrical equipments. In order to retain the data reliability of TPMS, we propose an assessment method of the data reliability based on signal-to-interference and noise ratio (SINR) of the received signal. The proposed technique can be widely applied to wireless duplex communication systems based on various sensors. We verify critical SINR values to satisfy data reliabilities of 95%, 97%, and 99% through computer simulation.

• Journal of Ocean Engineering and Technology
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• v.24 no.6
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• pp.76-80
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• 2010

Oil hydraulic piston pumps are being extensively used around the world, because of their simple design, light weight, effective cost, etc. An oil hydraulic pump is likely to have the serious problems of high leakage, friction, and low energy efficiency after a long period of use. In an oil hydraulic piston pump, the clearance between the valve block and piston plays an important role for volumetric and overall efficiency. In this study, the wear property of the SACM645 material with DLC coating used for a hydraulic piston pump was determined by experimentation with variable heat treatment. To investigate the effect according to the piston surface condition, five different types of specimens were prepared. The maximum tensile strengths of the QT and QT Nitration specimens had similar values of about 800 MPa, but the strains indicated a big difference. In a wear test, the wear characteristic of the DLC coating specimen was shown to be excellent. The QT, QT + IH, QT + Nitration, and matirx specimen showed similar wear characteristics. In the case of a dry condition without oil, the DLC coating specimen had good wear resistance, with no wear shown.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.49-58
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• 2003

Underground flexible pipes for electric cables are subject to external loads and surrounding soil pressure. Particularly, strain of flexible pipes is of great concern in terms of safety and maintenance for electric cables. In this paper, stress and strain of flexible pipes with various installation depth are compared using traditional formula, FEM analysis, model soil box test and field test. from the findings of various analyses, considering the strain criteria-maximum 3.5%, it is suggested that flexible pipes can be buried at the depth of 80cm without additional soil improvement.

• The Journal of Bigdata
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• v.4 no.2
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• pp.207-220
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• 2019

Recent developments in information and communication technology has enabled the deployment of sensor based data to provide real-time services. In Korea, The Korea Transportation Safety Authority is collecting driving information of all commercial vehicles through a fitted digital tachograph (DTG). This information gathered using DTG can be utilized in various ways in the field of transportation. Notably in autonomous driving, the real-time analysis of this information can be used to prevent or respond to dangerous driving behavior. However, there is a limit to processing a large amount of data at a level suitable for real-time services using a traditional database system. In particular, due to a such technical problem, the processing of large quantity of traffic big data for real-time commercial vehicle operation information analysis has never been attempted in Korea. In order to solve this problem, this study optimized the new database server system and confirmed that a real-time service is possible. It is expected that the constructed database system will be used to secure base data needed to establish digital twin and autonomous driving environments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.1 s.256
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• pp.26-35
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• 2007

The vehicle of urban transit is a complex system that consists of various electric, electronic, and mechanical equipments, and the maintenance cost of this complex and large-scale system generally occupies sixty percent of the LCC (Life Cycle Cost). For reasonable establishing of maintenance strategies, safety security and cost limitation must be considered at the same time. The concept of system reliability has been introduced and optimized as the key of reasonable maintenance strategies. For optimization, three preceding studies were accomplished; standardizing a maintenance classification, constructing RBD (Reliability Block Diagram) of VVVF (Variable Voltage Variable Frequency) urban transit, and developing a web based reliability evaluation system. Historical maintenance data in terms of reliability index can be derived from the web based reliability evaluation system. In this paper, we propose applying inverse problem analysis method and hybrid neuro-genetic algorithm to system reliability optimization for using historical maintenance data in database of web based system. Feed-forward multi-layer neural networks trained by back propagation are used to find out the relationship between several component reliability (input) and system reliability (output) of structural system. The inverse problem can be formulated by using neural network. One of the neural network training algorithms, the back propagation algorithm, can attain stable and quick convergence during training process. Genetic algorithm is used to find the minimum square error.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.7-12
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• 2007

Previously study on structural design of the main wing of the twenty-seat class WIG (Wing in Ground Effect) craft. In the final design, three spars construction was selected for safety in the critical flight load, and the Carbon-Epoxy material was selected for lightness and structural stability. In this study, the forced vibration analysis was performed on the composite main wing structure of the twenty-seat class WIG craft with two-stroke pusher type reciprocating engine. The vibration analysis based on the finite element method was performed using a commercial FEM code, MSC/NASTRAN. Excitations for the frequency response analysis were assumed as the Y-mode (lateral mode), the Z-mode (vertical mode) and the $M_{xyz}$-mode (twisted mode) which are typical main vibration modes of engine. And excitations for the transient response analysis were assumed as the X-mode (longitudinal mode) with the oscillating propeller thrust which occurs in operation.

• Structural Engineering and Mechanics
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• v.61 no.3
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• pp.419-426
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• 2017

Recently, the transportation of dangerous explosive goods is increasing, which makes vehicle blasting accidents a potential threat for the safety of bridge structures. In addition, blasting accidents happen more easily when earthquake occurs. Excessive dynamic response of bridges under extreme loads may cause local member damage, serviceability issues, or even failure of the whole structure. In this paper, a new explosion-proof and aseismic system is proposed including cable support damping bearing and steel-fiber reinforced concrete based on the existing researches. Then, considering one 40m-span simply supported concrete T-bridge as the prototype, through scale model test and numerical simulation, the dynamic response of the bridge under three conditions including only earthquake, only blast load and the combination of the two extreme loads is obtained and the applicability of this explosion-proof and aseismic system is explored. Results of the study show that this explosion-proof and aseismic system has good adaptability to seism and blast load at different level. The reducing vibration isolation efficiency of cable support damping bearing is pretty high. Increasing cables does not affect the good shock-absorption performance of the original bearing. The new system is good at shock absorption and displacement limitation. It works well in reducing the vertical dynamic response of beam body, and could limit the relative displacement between main girder and capping beam in different orientation so as to solve the problem of beam falling. The study also shows that the enhancement of steel fibers in concrete could significantly improve the blast resistance of main beam. Results of this paper can be used in the process of antiknock design, and provide strong theoretical basis for comprehensive protection and support of girder bridges.