• Journal of Aerospace System Engineering
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• v.10 no.4
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• pp.75-83
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• 2016

This paper presents a survey of patents and an analysis of a conceptual study for the development of rotor drive systems in combined unmanned rotorcraft in. The patents were classified into 10 cases with respect to the rotor drive system development, and these are reviewed and analyzed in detail. The results describe development concepts for rotor drive systems for vehicles obtained through the patent analysis.

• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.1-8
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• 2018

The fuel pump, which is used for an aircraft, was first developed in Korea through the Civil-Military Dual Components Development Program. The BLDC motor type, which is superior to the DC brush motor when considering efficiency, endurance, and explosive environmental characteristics, was applied to the fuel pump given its capacity and operating condition. The magnetic flux of the permanent magnet was analyzed based on the magnet flux density equation, using the Maxwell equation and the environmental condition. The motor performance, according to the load, was analyzed using the finite element method in order to design validation. The motor assembly was developed by designing the motor drive and the EMI filters. The performance test results of the motor assembly for the fuel boost pump were consistent with the analysis.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.236-244
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• 2007

The 40% scaled vehicle of Smart UAV has been developed for the investigation of basic flight characteristics and the verification of flight control algorithm. The similar gimbal hub and drive train with the full scale UAV were implemented and a forced air cooling reciprocating engine was installed. The various kind of tests were conducted for the major components of the vehicle. The important performance and mechanical endurance of the fabricated vehicle were identified by ground and hovering test.

• Journal of Drive and Control
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• v.13 no.4
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• pp.89-94
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• 2016

• Journal of the Korean Society for Precision Engineering
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• v.26 no.9
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• pp.31-37
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• 2009

• Journal of Drive and Control
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• v.17 no.4
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• pp.1-7
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• 2020

In orchard or crop-growing environments, pesticides are sprayed using various nozzles to prevent pests and improve productivity. Nozzles currently in use are restricted for use in multi-purpose environments, thus, it is necessary to develop new nozzles. In this study, new two-phase nozzles are proposed to improve the performance of the nozzle (flow rate, spray angle, spray particle size). The performance of the two-phase nozzles are predicted through the CFD analysis and the performance of the nozzles is compared with the experiment. The experimental results showed that the proposed two-phase nozzles are available at relatively low operating pressure condition and are capable of extensive spray particle size control. Thus, the proposed nozzles are expected to be available in various orchard environments.

• Journal of Drive and Control
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• v.18 no.4
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• pp.35-42
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• 2021

A personal mobility withstanding function for the disabled and vulnerable groups with difficulties in mobility was developed and structural and dynamics analysis was conducted. Personal mobility devices are a very helpful means of transportation for the disabled and vulnerable groups. In addition, the standing function allows individuals to perform a difficult task in while seated and offers a medical advantage to the user. In this study, a personal mobility device was designed and developed to help vulnerable groups and disabled people overcome limited mobility, and communicate with the general people at eye level through standing functions. Through structural and dynamic analysis, the structural safety, optimal speed during rotation, and lateral acceleration of the personal mobility device was analyzed. The analysis results are expected to contribute to the improvement of the users' convenience and stability of personal mobility.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.172-179
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• 2000

In this paper a technology for the fabrication of the oblique structure using the LIGA process will be presented. The fabricated microstructure is a tetrahedral 3- facet mirror. The mirror has an equilateral triangular base of hundreds ${\mu}m$ length mirror-like three side-facets inclined to the base at 45$^{\circ}$ and knife edges. Two regular triangles of 45$^{\circ}$ and tan-12. After development the shaded part of the PMMA the tetrahedral mirror remains, The completed mirror shows excellent aspects of mirror-like facets and knife-edges. By controlling the gap between the mask and the substrate the size of mirror easily can be changed. This mirror would be used as a laser beam splitter for the feedback control of the HDD slider.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.2
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• pp.133-139
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• 2017

The timing chain system, which is a typical power transmission technology applied to a vehicle, has been widely used by the automotive industry because it is normally designed to last a car's lifetime. However, the timing chain system may cause some problems due to the shape of the chains and the polygonal behavior on contact between the chain and the sprocket. In addition, noise and vibration caused by transmission error are the most typical problems encountered by major automotive manufacturers and they are considered as the main source of customer complaint. The initial tension of the chain-sprocket system is thought to be the main cause of transmission error, and it is regarded as the source of engine vibration and noise. The initial tension of the chain system should be controlled carefully since a low initial tension can cause twisting, which may lead to a system malfunction, while a high initial tension can reduce the service life due to a worn down contact surface. In this paper, the kinematic analysis model is generated with various initial tensions, which are controlled by changing the shape of the fixed guide with the largest contact surface with chain. The results showed that the transmission error was minimized on a particular range of initial tension, and the tendency showed that the error changed with a higher sensitivity at a lower initial tension.

• Journal of Information Management
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• v.21 no.2
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• pp.9-23
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• 1990

CD-ROM technique, not more than 10 years after development, goes through rapid growth, has been taken advantage of several practical application parts. Needless to say about bibliographic data, numeric value, the phonetics, an image and a picture data that are recorded as abstract or full text, and offered and applied to industry, information service including library, it can be used for library staffs, information retrieval. Escape from the need of one disc drive and one computer to access one disc, now we organize an ideal system that can be retrieved several CD-ROM used only one drive, several users can access several information, so networking is possible through LAN. In this article, we studied the function and type, characteristics, system, structure, data block, production procedure, standardization of CD-ROM LAN.