• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.5
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• pp.56-64
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• 2006

Station collocation of closely placed multiple GEO spacecraft is required to avoid the problem of collision risk, attitude sensor interference and/or occultation. This paper presents the method of obtaining the orbit correction scheme for collocating two GEO spacecraft within a small station-keeping box. The relative motion of each spacecraft with respect to the virtual geostationary satellite is precisely expressed in terms of power and trigonometry functions. This closed-form orbit propagator is used to define the constraint conditions which meet the requirements for the station collocation. Finally, the technique of constrained optimization is used to find the orbit maneuver sequence. Nonlinear simulations are performed and their results are compared with those of the classical method.

• Journal of Advanced Navigation Technology
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• v.3 no.2
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• pp.139-146
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• 1999

A flight simulator is composed of engine, navigation systems and instrument modules. However, two problems exist here. First, the coordinate of each independent module is not same. To solve this problem, we design a method that mutual coordinates are capable of transformation each other. Second, the distance and bearing between two points on the earth are computed in a sphere shape using the spherical trigonometry. However, the computing time is very severe. In this paper, we project the sphere into the planar to reduce the computing time. An experimental result shows that the performance of the proposed method is excellent to both distance and bearing calculations in close region. Also, the computing time is reduced from $4.95{\times}10^{-4}$ seconds to $1.648{\times}10^{-4}$ seconds.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.641-642
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• 2010

Trigonometric functions is the study based on the most simple and unique properties of right triangle that if an angular size was settled, the value of the ratio of these sides is constant regardless of the size of the triangle. If it is the angle of right triangle with the length of the lower base and the measured angle of building, the height of the building can be obtained by using trigonometry. it is considered as a good way to gauge the height of the building as the car moves.

• Journal of information and communication convergence engineering
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• v.7 no.3
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• pp.366-371
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• 2009

A realization for an accurate position detecting system of a moving target in two dimensional plane using dual line CCDs and photometric interpolation is presented. The system is realized that the infrared LEDs are utilized for lighting source, a target size is recognized by the scanned data from CCD owing to blocking the radiated light path by placing the target between CCD and lighting source, a coordinate on the plane is found by plane trigonometry formed by the moving target and two CCD sensors, and the former scan data is used for the coordinate iteratively and the photometric interpolation is applied to sub-pixel of scanned image. The experimental results show that the experiment results in a success rate about 3 different size targets, 3, 5 and 7mmm on the test plane $210{\times}373mm$. The moving target positioning detected success rate is 93% in 3mm target, 5mm is 95.3%, and 7mm is 95.8% respectively. The photometric interpolation is enhanced to 1.5% in comparison to be unused.

• The Journal of the Acoustical Society of Korea
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• v.35 no.6
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• pp.411-418
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• 2016

In this paper, we developed a new method estimating the location of ballistic missile launching using infrasound signals. Infrasound signal generated from the North Korea's ballistic missile launch was used as source data and its signal was recorded at KMA (Korea Meteorological Administration) infrasound stations located at Cheorwon and Yanggu. Time-frequency analysis, TDOA (Time Delay of Arrival) method and spherical trigonometry were applied for data processing of signal recorded and occurrence location detection. We could confirm the outstanding performance of the algorithm estimating source location which was only 3 km apart from the actual launching site.

• Journal of the Korea Society of Computer and Information
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• v.26 no.6
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• pp.37-46
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• 2021

In this paper, we designed and implemented a program to measure and to judge the accuracy of yoga postures using Azure Kinect. The program measures all joint positions of the user through Azure Kinect Camera and sensors. The measured values of joints are used as data to determine accuracy in two ways. The measured joint data are determined by trigonometry and Pythagoras theorem to determine the angle of the joint. In addition, the measured joint value is changed to relative position value. The calculated and obtained values are compared to the joint values and relative position values of the desired posture to determine the accuracy. Azure Kinect Camera organizes the screen so that users can check their posture and gives feedback on the user's posture accuracy to improve their posture.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.249-256
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• 2004

KRISO/KORDI is currently developing a deep-sea unmanned underwater vehicle (UUV) system which is composed of a launcher, an ROV, and an AUV. Two USBL acoustic positioning systems will be used for UUV's navigation. One is for the deep sea positioning of all three vehicles and the other is for AUV's guidance to the docking device on the launcher. In order to increase the position accuracy MFSK(Multiple Frequency Shift Keying) broadband signal will be used. As the first step to the implementation of a USBL system, this paper studies USBL positioning algorithm using MFSK signals. Firstly, the characteristics of MFSK signal is described with various MFSK parameters: number of frequencies, frequency step, center frequency, and pulse length. Time and phase delays between two received signals are estimated by using cross-correlation and cross-spectrum methods. Finally an USBL positioning algorithm is derived by converting the delays to difference of distances and applying trigonometry. The simulation results show that the position accuracy is improved highly when both cross-correlation and cross-spectrum of MFSK signals are used simultaneously.

• Journal for History of Mathematics
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• v.2 no.1
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• pp.9-27
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• 1985

Islam toot a great interest in the utility sciences such as mathematics and astronomy as it needed them for the religious reasons. It needeed geometry to determine the direction toward Mecca, its holiest place: arithmetic and algebra to settle the dates of the festivals and to calculate the accounts lot the inheritance; astronomy to settle the dates of Ramadan and other festivals. Islam expanded and developed mathematics and sciences which it needed at first for the religious reasons to the benefit of all mankind. This thesis focuses upon the golden age of Islamic culture between 7th to 13th century, the age in which Islam came to possess the spirit of discovery and learning that opened the Islamic Renaissance and provided, in turn, Europeans with the setting for the Renaissance in 14th century. While Europe was still in the midst of the dark age of the feudal society based upon the agricultural economy and its mathematics was barey alive with the efforts of a few scholars in churches, the. Arabs played the important role of bridge between civilizations of the ancient and modern times. In the history of mathematics, the Arabian mathematics formed the orthodox, not collateral, school uniting into one the Indo-Arab and the Greco-Arab mathematics. The Islam scholars made a great contribution toward the development of civilization with their advanced the development of civilization with their advanced knowledge of algebra, arithmetic and trigonometry. the Islam mathematicians demonstrated the value of numerals by using arithmetic in the every day life. They replaced the cumbersome Roman numerals with the convenient Arabic numerals. They used Algebraic methods to solve the geometric problems and vice versa. They proved the correlation between these two branches of mathematics and established the foundation of analytic geometry. This thesis examines the historical background against which Islam united and developed the Indian and Greek mathematics; the reason why the Arabic numerals replaced the Roman numerals in the whole world: and the influence of the Arabic mathematics upon the development of the modern mathematics.

• Journal of Satellite, Information and Communications
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• v.9 no.1
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• pp.90-96
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• 2014

This paper is about increasing transfer efficiency of wireless power transmission. The new method is proposed to detect the alignment of transmitter and receiver of wireless charger and so smart phone can display the position of wireless charging receiver on its LCD panel for the maximum charging efficiency. The previous method is only to show the transfer efficiency, but this method is to show not only the efficiency but also coordinates of receiver. The apparatus of the wireless charger is based on WPC(Wireless Power Consortium) standard and has planar air coil combined with magnet shield in Tx and Rx device so that the leakage flux is minimized on condition of under hundreds of kHz operating frequency. In this paper, it's showed that relation of magnet field and distance of each coils can be linearized and position information of Tx and Rx device is calculated thru trigonometry. Through the experiment, the obstacles of linearity are discovered and also showed that it can be optimized. and so the presented method is suitable for alignment detection method of Tx and Rx device in WPC wireless charger.

• Journal of Astronomy and Space Sciences
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• v.23 no.1
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• pp.71-90
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• 2006

This study is about , which constitutes Honcheonui(an armillary sphere) put of $\ulcorner$Uigijipseol$\lrcorner$ (Volume I) together with and -dealt with earlier than this subject. The study's construction on the text of is organized into 15 categories, including installation, observations, instructions for use, astronomical theories and formulas, etc. This study provides easy-to-understand illustrations of the figures shown in the original and contains detailed descriptions of the related calculation procedures. In the 'Instructions for Use of Honcheonui' discussed here, the readers are introduced to astronomical computation systems, mainly based on spherical trigonometry and proportional methods. The section also provides systematic and detailed reviews of astronomical theories and calculation procedures, allowing you to assess the level of astronomy knowledge at that time.