• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.64.1-64
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• 2001

Errors in inertial navigation system(INS) can be divided into two major groups which are system related errors and modeling errors due to approximation and linearization. Measurement noise, calibration, and alignment errors make up the first group, whereas the uncertainties in the gravity vector fall in the second category and are important error source for high quality INS, especially during high altitude and and/or long time missions, when the gravity errors tent to build up. The quality of a medium to high accuracy INS depends on the knowledge of the local gravity field. In this paper, the feasibility of improving airborns INS by use of more accurate gravity model is studied. To make consistent comparisons, WGS-84 parameters are used and ...

• Advances in Traditional Medicine
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• v.9 no.3
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• pp.207-216
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• 2009

Bauhinia variegata Linn (Mountain Ebony) is a medium-sized, deciduous tree, found throughout India, ascending to an altitude of 1,300 m in the Himalayas. The plant is widely used by the tribals throughout India and popular in various indigenous systems of medicine like Ayurveda, Unani and Homoeopathy. Following the various traditional claims on utility of this plant in curing number of diseases, considerable efforts have been made by researchers to verify its utility through pharmacological screenings. The notable biological activities reported are anthelmintic, antiulcer, antitumour, antimicrobial, anti-inflammatory, antigoitrogenic, hepatoprotective and haemagglutination. Industrially, the plant is widely used for the manufacture of wood wool board, production of tannin, oil, gum and fibre. The plant is also utilized for afforestation to conserve the nature. In this article, a comprehensive account of the cultivation, microscopy, phytochemical investigation, traditional and biologically evaluated medicinal uses of B variegata is presented.

• Solar Energy
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• v.6 no.1
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• pp.24-30
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• 1986

A concentrating solar collector of parabolic-cylindrical type is designed and constructed to provide a heat source of higher temperature for drying processes. Usually collectors of concentrating type require such peripheral auxiliary units as solar tracking system, heat medium circulation pump and temperature controller. However in this study, for simplification's sake in the maintenance of a collector system, it is intended to design a concentrating collector system which does not furnish these auxiliary units by adapting natural circulation system instead of foced circulation and by adjusting collector system to solar altitude manually and periodically. And based on the experimental data, a conceptual design for a heat sources of 50KWt thermal output is presented and discussed.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.21-30
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• 2020

In this paper, we predicted the propagation loss for the air-to-ground (A2G) channel between the ground control system and the unmanned aerial vehicle (UAV) using the prediction model for the aircraft recommended by the International Telecommunication Union (ITU). We analyzed the network coverage of the aerial relay system based on the medium altitude UAVs by expanding it into the air-to-air (A2A) channel. Climate and geographic factors in Korea were used to predict propagation loss due to atmospheres. We used the measured data published by the Telecommunication Technology Association (TTA) for regional rainfall-rate and effective earth radius factors to increase accuracy. In addition, the aerial relay communication system used the key parameter of the common data link (CDL) system developed in Korea recently. Prediction results show that the network coverage of the aerial relay system broadens at higher altitude.

• Journal of Convergence for Information Technology
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• v.10 no.10
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• pp.123-127
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• 2020

In order to obtain the overall fire line information of medium and large forest fires at night, the ground control system was developed to determine whether forest fires occurred through real-time video clips and to calculate the location of the forest fires determined using the location of drones, angle information of video cameras, and altitude information on the map to reduce the time required for regular video matches obtained after the completion of the mission. To verify the reliability of the developed function, the error distance of the aiming position information of the flight altitude star and the image camera was measured, and the location information within the reliable range was displayed on the map. As the function developed in this paper allows real-time identification of multiple locations of forest fires, it is expected that overall fire line information for the establishment of forest fire extinguishing measures will be obtained more quickly.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1343-1351
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• 2014

Recent technological advances in wireless networks and microelectromechanical systems (MEMS) have led to the development of different types of mini-UAVs and their utilizations in various ways. This study endeavors to develop a low-cost mini-UAV with autonomous flight capability, in order to obtain geospatial information of a small or medium-sized area, and also assess its flight stability by comparing the predetermined flight paths against the actual flight paths. Based on a post-development flight test, stable flight has been proven achievable as follows: the maximum endurance speed is 1 hour, the flying distance is 50km, the horizontal accuracy of flight paths is about ${\pm}6{\sim}8m$, and the altitude accuracy is about ${\pm}8m$. Therefore, it is deemed that high-resolution images which can be utilized for geospatial information are obtainable. This indicates that a UAV flying at an altitude of 200m can acquire images across a $2km{\times}3km$ area on the ground within 25 minutes, which validates its high usability for obtaining high-solution images at low altitudes in the future.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.2
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• pp.129-138
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• 2012

A MDO study of a midium-sized solar powered High Altitude Long Endurance (HALE) UAV has been performed, focused on energy balance. In the MDO process, Vortex Lattice Method(VLM) is employed for the aerodynamic modeling of the vehicle, of which structural weight is estimated with the modeling proposed by Cruz. Tail volume ratios have been set as constants, while the location of tail surfaces is determined from longitudinal static stability criterion. By balancing the available energy from solar cells, battery, and altitude, with the energy-requirement of the vehicle, the possibility of continuous flight over 24-hours has been investigated. The solar radiation level is set as that of summer at the latitude of $36^{\circ}$ north. During the daytime, the aircraft climbs using solar energy, accumulating potential energy, which supplements energy balance during the night. Optimizations have been sought in size of the vehicle, its weight distribution, and flight strategy.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.2
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• pp.188-197
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• 2016

In this paper, we propose a method that represents a mathematical form of wave propagation by using the fact the refractive index determining wave propagation characteristic is a function of altitude. Proposed method uses Snell's law that expresses relationship between incident angle and refraction angle when incident wave passes medium having a different refractive index. We present the simulation results about wave propagation by setting the square of refractive index in the form of the polynomial for altitude and show that it is possible to estimate the coefficients of the polynomial through the angle information from vertical axis of multiple radar systems.

• Journal of The Geomorphological Association of Korea
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• v.19 no.1
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• pp.41-56
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• 2012

The purpose of this study is to look into the location environment of prehistoric and ancient remains (hereinafter referred as remains) in Daejeon Area. For the purpose of this, out of remains reported in investigation areas so far with the object of remains (total 22 places) of New Stone Age -Proto Three Kingdom period, geographical and Geomorphological analysis was conducted. The results are like the following. Most of the remains are distributed over hills especially flat surface - semi-gentle slope of hills. The bed rocks of the remains (21 places, about 95%) are composed of double-mica granite. The remains (19 places, 86%) retain 'the 1st-2nd small scale river and '5th or higher medium scale river'within comparatively short distance at the same time. The average altitude of remains is 71m and most remains are located over the altitude of 50 - 90m. The average gradient of hillslop where the remains are located is $6.7^{\circ}$ and the remains (15 places, 71%) are located over the gradient of about $0-15^{\circ}$. And the tendency that the higher the gradient of remains the smaller the number of remains was confirmed. From the above, it is judged that the inhabitants who lived in Daejeon Area at that time preferred hills with comparatively not high altitude and the earth's surface of low gradient and in addition they recognized water (river) as being important when they selected the location of settlement (or dwelling sites group).

• Weed & Turfgrass Science
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• v.7 no.1
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• pp.54-61
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• 2018

Zoysiagrass (Zoysia spp.) exists spotly in Indonesia and it has potential to be used in parks, golf courses, and football fields. Many football fields and golf course fairways use sand as top soil over native soil. This study aims to analyze growth and quality of two native zoysiagrasses Zis and Zim. Zis is a native zoysiagrass collected in sea-side and Zim is a native zoysiagrass collected in mountain area. Both types of zoysiagrasses were planted at field with altitude of 300 m with various growing media mixes of sand and reservoir's sediment. Thickness of the growing medium was 10 cm over an alfisol clay soil. Experimental plots were constructed using factorial completely randomized design with two native zoysiagrasses and 5 types of growing media. Two ecotypes of native zoysiagrasses showed different in growth habits combined with mixtures of growth media. Zim showed higher growing speed including more vigor with uniformity and texture than Zis. There were not significanthly differences on leaf color and root length between two ecotypes of native zoysiagrasses collected in Indonesia.