• Smart Structures and Systems
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• v.23 no.4
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• pp.347-357
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• 2019

A new methodology for mitigation of the wheel squealing is proposed and investigated based on the dithering control. The idea can be applied in railway lines particularly in urban areas. The idea is clearly presented, and applied to a validated model. A full-scale model including the vehicle, curved track and wheel/rail contact is developed in the time domain to analyze the possibility and level of wheel squeal noise. Comparing the numerical results with a field test, the model is validated in different levels namely i) occurrence, ii) squealing frequency and iii) noise level. Two different approaches are proposed a) dithering of the wheel with piezoelectric patches and b) dithering of the rail with piezoelectric stacks. The noise level as well as the wheel responses is compared after applying the control strategy. A parametric study is carried out and effect of the dithering voltage and frequency on the squealing noise is investigated. It is found that both the strategies perform quite effectively within the saturating threshold of piezoelectric actuators.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1611-1618
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• 2017

Recently, the development for USV-related technologies are actively growing up in military domain. The USV (unmanned surface vehicle) conducts various missions for national defense at maritime environment. For succeed the missions, the USV essentially needs an automatic and remote control platform which includes propulsion system, steering system, control system, power system and so on. In this paper, we developed an integrated control system for the platform equipments and verified effectiveness of the developed system. To do this, we designed a system architecture and implemented a main control system that processes and controls platform equipments by received command. Also we developed components of designed architecture such as engine control device, water-jet control device and power control device. For test and verify the developed system, we designed and made a test-bed of engine and water-jet with related parts, and proceeded a basin test for verifying the developed system based on the test-bed.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.299-304
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• 2023

Recently, drones have been used as a major means of attack drones in major wars around the world, and it seems likely that they will evolve into game changers in the future. Recently, drones have been used as a major means of attack drones in major wars around the world, and it seems likely that they will evolve into game changers in the future. In the major wars of the 21century, attack drones are used for precision fire-guided or self-destruct attacks, For the purpose of cognitive warfare, its territory is expanding not only to land and air, but also to sea and water. These attack drones will perform multi-domain operations, and for this purpose, the level of autonomy will be improved and High-Low Mix We will continue to develop by strengthening concept-based scalability. North Korea has also been making considerable efforts to operate attack drones for a long time, and activities such as third-country-level self-explosive drones, artificial intelligence-based clustered self-explosive drones, and self-destructive stealth unmanned semi-submersible are expected. In addition to North Korea's provocations and attacks, it is hoped that there will be a need for active follow-up research on our military's countermeasures and utilization plans.

• Journal of the Korean Geographical Society
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• v.37 no.3
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• pp.203-221
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• 2002

This study attempts to analyze the spatial characteristics of cyberspace and to map spatial variations of cyberspace. In order to analyze the spatial distribution of cyberspace, three measurement indices are selected such as commercial domain number, Internet backbone network, and Internet users, which are highly correlated to each other. The three sets of measurement showed that cyberspace in Korea is spreading in a highly uneven fashion, strongly favoring a few cities and unfavoring economically distressed cities. Seoul acts on overwhelmingly dominant role in cyberspace, by being concentrated a number of domains and having high-capacity bandwidth on Internet backbone network. Internet is selectively connecting several cities into highly interactive networks, while at the same time largely bypassing other cities. The development of Internet network through infrastructure investments at selected cities has resulted in an uneven accessibility and digital divide among cities. The regional disparity would be further reinforced by ICT development as the primary vehicle for unequal accessibility. The result of this study revealed that geography continues to matter, despite the recent rhetoric claiming of 'the death of distance'or 'the end of geography'.

• Journal of Digital Contents Society
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• v.19 no.1
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• pp.113-122
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• 2018

In level 3 automated vehicles, drivers are expected to encounter transition of control when the system reaches its limit. Drivers need to refocus their attention on the road ahead and gain situational awareness. Appropriate information should be conveyed during this period in order to prevent human errors. In this paper, we defined the takeover process as 'in-the-middle-of-the-loop' and conducted Task Analysis and Work Domain Analysis to find out information requirements. As a result, we specified required information types and interface considerations. Moreover, we conducted an experimental study to find how the information types affect drivers on situation awareness, cognitive load and reaction time. Consequently, we found different information on system transparency should be conveyed depending on the urgency of takeover situation and driver guidance could help drivers with better situation awareness after the takeover.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.5
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• pp.668-673
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• 2007

We propose the design of the warfighting experiment process for software intensive systems using the intelligent maturity model and suggest the application results of the target searching capability in smart UAV. For this, we design the intelligent maturity model to evaluate the intelligent degree of the software intensive systems considering the domain and intelligent level. Then we classify the IS0/1EC-12207 process and CMMI process as LITO domain for designing the warfighting experiment process, map the classifed process to the five factors of the warfighting experiment and derive the process as warfighting experiment element and phase. Based on the derived process, we design the warfighting experiment process using the IDEF0. Finally we apply the proposed process to the target search capability and suggest the results which are required to develop and acquire the smart UAV.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.6
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• pp.299-310
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• 2022

The ability of an automated driving system is based on vehicle sensors, judgment and control algorithms, etc. The safety of automated driving system is highly related to the operational status of the road network and compliant road infrastructure. The safe operation of automated driving necessitates continuous monitoring to determine if the road and traffic conditions are suitable and safe. This paper presents a node and link system to build a road monitoring system by considering the ODD(Operational Design Domain) characteristics. Considering scalability, the design is based on the existing ITS standard node-link system, and a method for expressing the monitoring target as a node and a link is presented. We further present a technique to classify and manage hazard risk into five levels, and a method to utilize node and link information when searching for and controlling the optimal route. Furthermore, we introduce an example of system implementation based on the proposed node and link system for Sejong City.

• Journal of the Korea Convergence Society
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• v.4 no.2
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• pp.21-27
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• 2013

Spot welding is automation of assembly process, without increasing the vehicle weight and economy, there is a fuel economy improvement of motor vehicles and to widely used in the automotive industry. But By irregular load from the road surface while at the vehicle is running, stress concentration occurs in the weld point, fatigue failure occurs frequently. Considering change of stiffness is the essential fatigue life of the evaluation spot weld. In this paper, by performing a linear static analysis was to understand the vulnerable part. Acquire to the fatigue properties of the spot weld, take the load history of the three levels in the time domain, was performed by setting as a condition of quasi-static fatigue analysis. and Fatigue life prediction method of the spot weld was by applying the method according to the fatigue damage accumulation and the conventional method was compared analyzed with the results shown.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3125-3134
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• 2010

Three-way catalyst durability in the Korea requires 5 years/80,000km in 1988 but require 10 years/120,000km after 2002. Domestic three-way catalyst satisfies exhaust gas conversion efficiency or pressure drop etc. but don't satisfy thermal durability. Three-way catalyst maintains high temperature in interior domain but maintain low temperature on outside surface. This study evaluated thermal durability of three-way catalyst by thermal flow and structure analysis and the procedure is as followings. Thermal flow parameters ranges were determined by vehicle test and basic thermal flow analysis. Response surface for rear catalyst temperature was constructed using the design of experiment (DOE) for thermal flow parameters. Thermal flow parameters for rear catalyst temperature in vehicles examination were predicted by desirability function. Temperature distribution of three-way catalyst was estimated by thermal flow analysis for predicted thermal flow parameters.

• Journal of Advanced Navigation Technology
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• v.16 no.4
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• pp.619-626
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• 2012

One-way Network-RTK(Real Time Kinematics) is considered as a method which can satisfy moving vehicle's recently-required high accuracy and mobility. When we use one-way Network RTK for vehicle navigation, multiple cells-based system is required to provide the service continuously in wide area. The rover which moves through various cells inevitably experiences a correction discontinuity, which is not eliminated by the DD(Double Difference) method and to cause 13cm(horizontal) and 48cm(vertical) position error. We suggest three solutions to reduce this discontinuity, which are identification of master RS with neighbor networks, duplication of communication module to receive corrections from other cells, and ambiguity adjustment between neighbor cells. All of our suggestions reduce the error to 1/4 wavelength in measurement and 3cm in position-domain, and we suggest the ambiguity adjustment is the best when we consider the extendibility of service area and the cost of rover device.