• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.1
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• pp.35-42
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• 2010

The rapid economic development induced the massive road constructions, becoming bigger and high-speed of the vehicles. However, it brings lots of social problems, such as air pollutions, traffic noise and vibration. Special concrete block for the base course of asphalt pavement is needed to decrease traffic noise such as tire's explosive and vehicles sound, applying Helmholtz Resonators theory to asphalt pavement. If it is applied to the area where it happens considerable noise such as a junction, the street of a housing complex and a residential street, it is one of considerable method to solve the social requirements of noise problem. This research examines couple of laboratory tests for the sound absorption effect of the concrete block and the base concrete block. There are specimens which is fixed hall-size, space, depth as the condition of this research, and these are analysed of noise decrease effect using different condition of the first noise of each vehicle. As a result of analysis data according to vehicle noise volume, measurement distance, a form and size of the hall using the base concrete block, the use of special concrete base showed a good alternative solution for decreasing traffic noise level, from 4 dB to 9 dB.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.5
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• pp.121-133
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• 2017

Since the mid 1990s, policies have been actively promoted to improve safety and pedestrian environment around the school such as the improvement of School zone. However, the prevention of accidents was not effective because it did not extend to the school road where the main transportation route for children's commuting takes place. In addition, due to the rapid increase of automobiles, trunk road traffic in the peak time bypasses the back roads, which threatens children's safety and the environment by invading the school area, which is the main living space of children. In this study, the characteristics of domestic children's traffic accidents were investigated and the problems were analyzed by conducting a field survey on Yeouido Secondary School in Seoul and Unjung Elementary School in Gyeonggi Province. In addition, Variable speed limit signs and Beacons were installed in the pedestrian road of comunity including School zone, and the effects of facilities on the speed of vehicles were analyzed. As a result of the analysis, the Variable speed limit sign showed a deceleration effect of about 8.3km/h, and the Beacon showed a phenomenon in which the traveling speed of 0.8km/h increased only slightly. In addition, the traffic violation rate of passenger cars, buses, and lorries decreased by about 3% as a result of investigating the number of traffic violation vehicles before and after installation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.1
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• pp.94-106
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• 2020

Recently, the radio navigation method utilizing the GPS(Global Positioning System) satellite information is widely used as the method to measure the position of objects. As GPS applications become wider and fields based on various positioning information emerge, new methods for achieving higher accuracy are required. In the case of autonomous vehicles, the INS(Inertial Navigation System) using the IMU(Inertial Measurement Unit), and the DR(Dead Reckoning) algorithm using the in-vehicle sensor, are used for the purpose of preventing degradation of accuracy of the GPS and to measure the position in the shadow area. However, these positioning methods have many elements of problems due not only to the existence of various shaded areas such as building areas that are continually enlarged, tunnels, underground parking lots and but also to the limitations of accumulation-based location estimation methods that increase in error over time. In this paper, an efficient positioning method in a large underground parking space using Fingerprint method is proposed by placing the AP(Access Points) and directional antennas in the form of four anchors using WLAN, a popular means of wireless communication, for positioning the vehicle in the GPS shadow area. The proposed method is proved to be able to produce unchanged positioning results even in an environment where parked vehicles are moved as time passes.

• The Korean Journal of Emergency Medical Services
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• v.6 no.1
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• pp.103-128
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• 2002

As a result of trying the various manufacturing methods considering the reality of manpower and equipments with this manual, the following standardized procedures and contents can be suggested. (1) Since tools presenting Rock-Drill data must formalize the order of explanation although explainers are different, it will be valid that it is configured by existing power point method rather than by web document type. Composition of contents are selected on the basis of defence card and survey and then 8 items including initial screen, peripheral conditions, mobilization route, general conditions, use and structure by floor, department of vehicle consideration in activities and end screen are included. (2) Making methods and cautions of data included and used in power point are as follows ; - It was most effective that objects of fire fighting and location of neighboring fire fighting water were expressed by electronic map and drawing of inner building was made by scanning it after paining general architecture drawing(plan by each floor) rather than using drawing tools of EXCEL program or CAD drawing. And it was helpful to simplify contents of architecture drawing to wall, stairs and gate in understanding them. - Photographing of video data should be taken to show available fire fighting facilities in fire, use of planned space and the whole inner structure of each floor from the inside of fire fighting buildings and to display play time between 10 sec. and 1 min, for obstacles to distance from adjacent buildings or passage of special vehicles and fire fighting water from the outside of the building. - File format of video data taken in this way is most suitable to use wmv(window media video) or asf(advanced streaming format) type in consideration of time required for export, screen quality, file capacity and play type in Rock-Drill through network. - Still screen(photo) is more effective to express the department of fire fighting vehicles or other equipments than using video. (3) In configuration work of power point, hyper link was used most and configured to see any part at any situation like web document and then uniformity of presentation order of power point was complemented. (4) In case of sales facilities with the area of $35.557m^2$, the time of 22 hours and 30 minutes for five days was taken with five persons. Therefore, when eight-hour works a day were calculated, the whole process of video work for Rock-Drill can be finished with three day works.

• Journal of Navigation and Port Research
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• v.30 no.10 s.116
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• pp.855-860
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• 2006

In the environment where multiple AGVs(Automated Guided Vehicles) operate concurrently in limited space, collisions, deadlocks, and livelocks which have negative effect on the productivity of AGVs occure more frequently. The accelerated motion of an AGV is also one of the factors that make the AGV routing more difficult because the accelerated motion makes it difficult to estimate the vehicle's exact travel time. In this study, we propose methods of avoiding collisions, deadlocks, and livelocks using OAR(Occupancy Area Reservation) table, and selecting best route by estimating the travel time of an AGV in accelerated motion. A set of time-driven simulation works validated the effectiveness of the proposed methods.

• Journal of Aerospace System Engineering
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• v.14 no.5
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• pp.42-48
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• 2020

This research illustrates how the hybrid engine system comprising of a two-cycle reciprocal engine with an integrated generator and a battery is prepared for the design process. The purpose of this research is to increase flight endurance taking advantage of the high energy density of hybrid propulsion systems as well as to cope with current environmental issues by reducing fossil fuel. The hybrid system is designed to offer 6 kW power, and the power can be adjusted by controlling the engine's RPM in accordance with load variations. In addition, the battery is adopted to offer extra electric power that this hybrid system cannot cover, and can function as the main power source in limited time in the case of an emergency situation. Besides that, the generator is directly mounted on an engine crank-shaft, and in turn, they can share the same RPM. Thus, it is hypothesized that this integration method can make a compact design possible by reducing space for the installation in the fuselage of UAVs.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.565-569
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• 2004

The wing-body trucks are special vehicles that are designed to provide large carrying space and to protect the freights from outside impacts and bad weather. They are constructed to the structure opening and shutting three-layered aluminum top. In the middle- and large-size(above one-ton) wing-body trucks, wing-body is opened/closed by opening and shutting device of oil pressure type. But one-ton truck is constructed that its wing-body is opened/closed in manual to use helping of stay-dampers. So, we developed an electronic opening and shutting device for one-ton wing-body trucks to improve the inconvenience of usage for manually operated wing-body. The developed device is consisted of two connected links and a dc motor combined with an worm gear. The worm gear changes the rotation axis of the dc motor to a right-angled direction and transfers the torque of dc motor to the links. The two connected links open/shut the wing-body using the torque transferred from the dc motor. When the wing-body starts to be opened, the biggest torque is required from the dc motor for opening the wing-body. And as the wing-body is opened more and more, the required torque is smaller for opening the wing-body. Thus, the structure of two connected links are designed to locate at the center of worm gear so that maximum torque of the dc motor is transferred the links at the initial time starting to open wing-body. The controller of the device with open and closed buttons also is designed to protect the device from over-opening and over shutting operations. The developed device is accomplished for many experiments using actual vehicle. Those experiments show that the device has more excellent performance than the oil pressure type.

• Advances in aircraft and spacecraft science
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• v.4 no.6
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• pp.729-744
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• 2017

This investigation highlights rationale of electrically conductive nano adhesives for its essential application for Electromagnetic Interference (EMI) Shielding in satellites and Lightning Strike Protection in aircrafts. Carbon Nano Fibres (CNF) were functionalized by electroless process using Tollen's reagent and by Plasma Enhanced Chemical Vapour Deposition (PECVD) process by depositing silver on CNF. Different weight percentage of CNF and silver coated CNF were reinforced into the epoxy resin hardener system. Scanning Electron Microscopy (SEM) micrographs clearly show the presence of CNF in the epoxy matrix, thus giving enough evidence to show that dispersion is uniform. Transmission Electron Microscopy (TEM) studies reveal that there is uniform deposition of silver on CNF resulting in significant improvement in interfacial adhesion with epoxy matrix. There is a considerable increase in thermal stability of the conductive nano adhesive demonstrated by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Four probe conductivity meters clearly shows a substantial increase in the electrical conductivity of silver coated CNF-epoxy composite compared to non-coated CNF-epoxy composite. Tensile test results clearly show that there is a significant increase in the tensile strength of silver coated CNF-composites compared to non-coated CNF-epoxy composites. Consequently, this technology is highly desirable for satellites and EMI Shielding and will open a new dimension in space research.

• Journal of Power Electronics
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• v.17 no.2
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• pp.490-500
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• 2017

Fuel cell (FC) is a promising power supply in electric vehicles (EV); however, it has poor dynamic performance and short service life. To address these shortcomings, a super capacitor (SC) is adopted as an auxiliary power supply. In this study, the frequency decoupling control method is used in electric vehicle energy system. High-frequency and low-frequency demand power is provided by SC and FC, respectively, which makes full use of two power supplies. Simultaneously, the energy system still has rapidity and reliability. The distributed power system (DPS) of EV requires DC-DC converters to achieve the desired voltage. The stability of cascaded converters must be assessed. Impedance-based methods are effective in the stability analysis of DPS. In this study, closed-loop impedances of interleaved half-bridge DC-DC converter and phase-shifted full-bridge DC-DC converter based on the frequency decoupling control method are derived. The closed-loop impedance of an inverter for permanent magnet synchronous motor based on space vector modulation control method is also derived. An improved Middlebrook criterion is used to assess and adjust the stability of the energy system. A theoretical analysis and simulation test are provided to demonstrate the feasibility of the energy management system and the control method.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.3
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• pp.75-86
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• 2004

KSR-III is the first Korean sounding rocket propelled by a liquid propellant propulsion system and it has been developed over 5 years using purely domestic technologies. The propulsion system of KSR-III is a 13-ton class see-level thrust liquid rocket engine(LRE) which utilizes liquid oxygen and kerosene for its propellants and employed pressurized propellant feeding and ablative cooling system. The problem of combustion instabilities which has brought the most difficulty in the development was resolved by implementation of a baffle. Through the development of KSR-III LRE, meaningful achievements have been made in the core technologies of LRE such as design of injectors and combustion chambers and test, evaluation, and control of combustion instabilities. The acquired technologies will be applied to the development of higher performance LREs necessary for future space development programs such as Korean Small Launch Vehicles(KSLV) In this paper, the development of KRE-III LRE system is described including its design, analyses. performance tests and evaluation.