• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.3
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• pp.245-250
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• 2010

In this paper, an efficient extraction technique of power lines is proposed. Power line extraction technique is used to operate unmanned autonomous vehicles. To achieve the extraction of power lines, an angle space segmentation and grouping method of Hough transform are developed. In simulation results for the proposed algorithm, our algorithm shows a good detection results in experiments for several aerial images which contain different line components.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.399-402
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• 2008

It is well known that helium saturated propellants significantly effects the dynamics of propulsion system, thruster cross coupling, water hammer and thruster performance. Especially for the propulsion systems, which have multiple high thrust engines, such as HTV(H-II transfer vehicle), the effect is more important. Therefore full-saturated propellants should be used at ground tests of HTV propulsion system and evaluate its effects. HTV is an advanced space vehicle being developed by Japan Aerospace Exploration Agency(JAXA) to enhance cargo delivery capabilities of the fleet of vehicles visiting the International Space Station(ISS). This paper presents an overview of the successful effort of the testing with saturated propellants(MMH/MON3) for HTV propulsion system during the ground firing tests.

• Journal of the Korean Society for Heat Treatment
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• v.32 no.1
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• pp.29-35
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• 2019

The remedial junction is found in the network of single walled carbon nanotubes after the irradiation of protons not only for the better mechanical strength but also for the higher property of electrical conductivity. The irradiated proton formed a beam transferred sufficient energy to change the sp2 structure of atomic carbon as much as damage of crystalline formation, however it is shown the cross bonding while recovery of structure. This improved network in 2-D atomic chain of carbon is expected to use in a critical part in space energy harvesting system related with the solar radiation.

• Electronics and Telecommunications Trends
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• v.38 no.5
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• pp.114-124
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• 2023

Recently, there have been the World Economic Forum's space economy guidelines, the International Telecommunication Union's regulations for each satellite orbit, the development of chips using satellite communication by global manufacturers and service providers, and the registration of key telecommunication businesses. Accordingly, trends in low-orbit 5G satellite communication services in Korea were investigated and analyzed, and the current situation in Korea was diagnosed. Korea's satellite communications accounts for 0.31% of all satellites when analyzed centering on countries with 20 or more satellites. Korea's communication satellite holdings are insufficient compared to 187 times that of the United States, 45 times that of Russia, and 18 times that of China. There is no link technology between 5G and LEO, and the cost of launch vehicles is high. In addition, it is judged that the ecosystem of equipment companies in the low-orbit 5G-NTN business model is insufficient.

• Journal of The Korean Astronomical Society
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• v.56 no.2
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• pp.263-275
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• 2023

The Sun-Earth Lagrange point L4 is considered as one of the unique places where the solar activity and heliospheric environment can be observed in a continuous and comprehensive manner. The L4 mission affords a clear and wide-angle view of the Sun-Earth line for the study of the Sun-Earth and Sun-Moon connections from he perspective of remote-sensing observations. In-situ measurements of the solar radiation, solar wind, and heliospheric magnetic field are critical components necessary for monitoring and forecasting the radiation environment as it relates to the issue of safe human exploration of the Moon and Mars. A dust detector on the ram side of the spacecraft allows for an unprecedented detection of local dust and its interactions with the heliosphere. The purpose of the present paper is to emphasize the importance of L4 observations as well as to outline a strategy for the planned L4 mission with remote and in-situ payloads onboard a Korean spacecraft. It is expected that the Korean L4 mission can significantly contribute to improving the space weather forecasting capability by enhancing the understanding of heliosphere through comprehensive and coordinated observations of the heliosphere at multi-points with other existing or planned L1 and L5 missions.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.5
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• pp.765-771
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• 2020

Automatic lubrication devices are applied in various fields, such as huge machinery, construction machinery or commercial vehicles, to lower maintenance costs and protect the devices. In addition, the automatic lubrication device reduces frequent component failures cause by friction and allows the machine to replace the lubricating oil replenishment work carried out by the manager. However, the automatic lubricating device used in large machinery or commercial vehicles is relatively large, containing a large amount of lubricant in the space to be lubricated. On the other hand, a smart factory, such as a home appliance or cosmetics factory, lacks space to install large automatic lubrication devices, and it is difficult to distribute electricity. Therefore, there is a need for an automatic lubrication device that can be used in various environments that require lubrication. In this paper, a small automatic lubrication device is proposed for smart factories that have changed parts of existing factories, such as electronics factories, to minimize friction arising from mechanical parts, etc. In particular, the structure of lubricating pumps and component parts that are the core of automatic lubrication devices was described so that they could be utilized in various fields. Finally, a test bed environment is established for the proposed automatic lubrication device to evaluate its performance and verify its applicability.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.10
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• pp.911-920
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• 2016

For the pitch and yaw axis attitude control of launch vehicle, thrust vector control which changes the direction of thrust during the engine combustion is commonly used. Hydraulic actuation system has been used generally as a drive system for the thrust vector control of launch vehicles with the advantage of power-to-weight ratio. Nowadays, due to the developments of highly efficient electric motor and motor control techniques, it has done a lot of research to adopt electro-mechanical actuator for thrust vector control of small-sized launch vehicles. This paper describes system design and test results of the prototype of direct drive electro-mechanical actuation system which is being developed for the thrust vector control of $3^{rd}$ stage engine of KSVL-II.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.4
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• pp.338-344
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• 2018

The lunar surface temperature is important as a environmental parameter for the thermal design of the lunar exploration vehicles such as orbital spacecraft, lander, and rovers. In this study, the temperature is numerically predicted through a simplified lumped system model for the energy conservation. The physical values required for the analysis of the energy equation are derived by considering the geometric shape, and the values presented in the previous research results. The areal specific heat, which is the most important thermo-physical property of the lumped system model, was extracted from the temperature measurements by the Diviner loaded on the LRO, and the value was predicted by calibration of the analytical model to the measurements. The predicted temperature distribution obtained through numerical integration has sufficient accuracy to be applied to the thermal design of the lunar exploration vehicles.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.4
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• pp.331-337
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• 2009

Space launch vehicles require highly reliable, lightweight structures. It is thus important to monitor the structural health of these components with nondestructive inspections. In this paper, we studied an example of a nondestructive inspection that was partially applied to the manufacture and inspection of a launch vehicle. Ultrasonic tests, X-rays, tapping, and acoustic emissions comprised the inspection method. A payload fairing, high pressure tank, fastener part, and bonding part were used as hardware to be inspected. We proposed a quantitative standard for debonding inspection of the payload fairing and acoustic emission data for the proof test of the high pressure tank. We analyzed the fracture mode of the sandwich fastener part according to frequency changes. We also proposed a standard specimen for ultrasonic inspection of bonds of different materials. The present analyses and results provide data for evaluation of the launch operation sequence to ensure launch vehicles afford high reliability.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.4
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• pp.309-320
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• 2012

Dynamic behaviors of the tunnel linings of curved tunnels with various curvatures are investigated to examine the effect of wind loads due to passing vehicles. In the case without backfill, the responses of the tunnel lining should be considered to examine the clearance of the lining. A steel tunnel lining is selected to see the influence of the wind load upon the tunnel lining more clearly. The wind pressure upon the lining is simplified into the pressure and suction while the vehicle passing the loading positions. As the radius of curvature decreases, the response decreases, showing that the strength against the deformation is found to increase since the asymmetry of the deformation shape is reduced. It is found that the responses increase as the passing vehicle speed increases.