• Journal of Drive and Control
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• v.19 no.4
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• pp.19-28
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• 2022

This paper introduces an automatic steering system for straight traveling capable of being mounted on drivable agricultural machinery which user can handle it such as a tractor, a transplant, etc. The modular automatic steering device proposed in the paper is composed of RTK GNSS, IMU, HMI, hydraulic valve, and wheel sensor. The path generation method of the automatic steering system is obtained from two location information(latitude and longitude on each point) measured by GNSS in advance. From HMI, a straight path(AB line) can be created by connecting latitude and longitude on each point and the device makes the machine able to follow the path. During traveling along the reference path, it acquires the real time position data every sample time(0.1s), compares the reference with them and calculates the lateral deviation. The values of deviation are used to control the steering angle of the machine using hydraulic valve mounted on the axle of front wheel. In this paper, Pure Pursuit algorithm is applied used in autonomous vehicles frequently. For the analysis of traveling characteristics, field tests were executed about these conditions: velocity of 2, 3, 4km/h which is applied to general agricultural work and ground surface of solid(asphalt) and weak condition(soil) such as farmland. In the case of weak ground state, two experiments were executed about no-load(without work) and load(with work such as plowing). The maximum average deviations were presented 2.44cm, 7.32cm, and 11.34cm during traveling on three ground conditions : asphalt, soil without load and with load(plowing).

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1197-1199
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• 2003

ROCSAT-2 mission is to daily image over Taiwan and the surrounding area for disaster monitoring, land use, and ocean surveillance during the 5-year mission lifetime. The satellite will be launched in December 2003 into its mission orbit, which is selected as a 14 rev/day repetitive Sun-synchronous orbit descending over (120 deg E, 24 deg N) and 9:45 a.m. over the equator with the minimum eccentricity. National Space Program Office (NSPO) is developing a ROCSAT-2 Image Processing System (IPS), which aims to provide real-time high quality image data for ROCSAT-2 mission. A simulated ROCSAT-2 image, based on Level 1B QuickBird Data, is generated for IPS verification. The test image is comprised of one panchromatic data and four multispectral data. The qualification process consists of four procedures: (a) QuickBird image processing, (b) generation of simulated ROCSAT-2 image in Generic Raw Level Data (GERALD) format, (c) ROCSAT-2 image processing, and (d) geometric error analysis. QuickBird standard photogrammetric parameters of a camera that models the imaging and optical system is used to calculate the latitude and longitude of each line and sample. The backward (inverse model) approach is applied to find the relationship between geodetic coordinate system (latitude, longitude) and image coordinate system (line, sample). The bilinear resampling method is used to generate the test image. Ground control points are used to evaluate the error for data processing. The data processing contains various coordinate system transformations using attitude quaternion and orbit elements. Through the qualification test process, it is verified that the IPS is capable of handling high-resolution image data with the accuracy of Level 2 processing within 500 m.

• The Journal of Bigdata
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• v.8 no.1
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• pp.73-82
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• 2023

Marine debris not only affects the survival of marine life, water pollution, and scenery but also has secondary effects on economic loss and human health. While research on underwater and surface debris is actively ongoing, solutions to marine debris in hard-to-reach blind spots are being developed slowly. To address this problem, we utilize drones to detect and track marine debris in blind spots such as tetrapods. The detected debris is then visualized by calculating its location coordinates using the drone's GPS, altitude, and heading values. The proposed method of using drones for detecting marine debris and matching it with longitude and latitude coordinates provides an effective solution to the problem of marine debris in blind spots.

• Smart Media Journal
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• v.8 no.2
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• pp.86-93
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• 2019

The purpose of this study is to develop walk score application GUI in a smart device for improving user convenience. This study uses the walk score dataset of Seoul City developed in previous studies. Application GUI consists of five parts: address input window and search button, detail information (address, latitude, longitude, walk score), window switching and input window for a number of data, data input window, and menu button. For verifying application GUI, this study uses 12 locations (sets of address, latitude, longitude, and walk score) near Gangnam Station and Myungdong Station in Seoul in several scenarios. First, this study checks if the application has been implemented with address and keyword search options. Then, new data insertion and file output operations are evaluated. The application system developed in this study operated properly in all scenarios. This walk score application can be a useful device in our daily lives.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.2
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• pp.193-199
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• 2013

This work investigates the orbital perturbations of the cubesats that lie on LEO due to Earth albedo. The motivation for this paper originated in the investigation of the orbital perturbations for closed- Earth pico-satellites due to the sunlight reflected by the Earth (the albedo). Having assumed that the Sun lies on the equator, the albedo irradiance is calculated using a numerical model in which irradiance depends on the geographical latitude, longitude and altitude of the satellite. However, in the present work the longitude dependency is disregarded. Albedo force and acceleration components are formulated using a detailed model in a geocentric equatorial system in which the Earth is an oblate spheroid. Lagrange planetary equations in its Gaussian form are used to analyze the orbital changes when $e{\neq}0$ and $i{\neq}0$. Based on the Earth's reflectivity data measured by NASA Total Ozone Mapping Spectrometer (TOMS project), the orbital perturbations are calculated for some cubesats. The outcome of the numerical test shows that the albedo force has a significant contribution on the orbital perturbations of the pico-satellite which can affect the satellite life time.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.9
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• pp.75-81
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• 2003

The longitude and latitude of a geosynchronous satellite are not defined as a point in space because of various external perturbations. To perform the missions of a satellite for a communication and broadcasting, the satellite must be positioned within a predefined station keeping box in given limited space longitude. In this study, we propose east-west station keeping box larger than that of north-south station. By using the derived error equation, we verified the Koreasat station keeping box allocation by assuming one week and two weeks of station keeping cycle.

• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.4
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• pp.234-244
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• 2013

This study was conducted to determine the factors affecting to seed characteristics and seedling growth of Zelkova serrata. The seeds were collected from sixteen populations of Z. serrata and the seed characteristics (i.e., seed length, width, weight and full seed rate) were measured. We also measured the 1-year-old seedling growth of each population at nursery. All seed characteristics showed significant differences in population level. Seed length and seed width were positively correlated with latitude, longitude, altitude and distance from coast line of sampling site. Seed length and seed width also negatively correlated with annual mean temperature, mean temperature of growing season (Mar.~Oct.). The ratio of seed length/seed width showed inverse trend in case of seed length and seed width. Seed weight/1,000 grains had no correlation with geographic factors but showed negative correlation with annual mean dryness index. Seed weight/L showed negative correlation with latitude and longitude and positive correlation with mean temperature of growing season of sampling site. Full seed rate showed negative correlation with latitude, longitude and annual mean dryness index of sampling site. There were significant differences among populations, among family within population and among individuals within family in seedling growth. Height and diameter of root collar of seedling showed negative correlation with longitude and mean humidity of growing season of sampling site. Height growth of seedlings was not correlated with any seed characteristics but, diameter at root collar showed low negative correlation with seed weight/1,000 grains and seed weight/L. We discussed the implications of the results in view of tree improvement of Z. serrata.

• Journal of Astronomy and Space Sciences
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• v.27 no.4
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• pp.359-366
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• 2010

In this study, we developed a global ionosphere model based on measurements from a worldwide network of global positioning system (GPS). The total number of the international GPS reference stations for development of ionospheric model is about 100 and the spherical harmonic expansion approach as a mathematical method was used. In order to produce the ionospheric total electron content (TEC) based on grid form, we defined spatial resolution of 2.0 degree and 5.0 degree in latitude and longitude, respectively. Two-dimensional TEC maps were constructed within the interval of one hour, and have a high temporal resolution compared to global ionosphere maps which are produced by several analysis centers. As a result, we could detect the sudden increase of TEC by processing GPS observables on 29 October, 2003 when the massive solar flare took place.

• Journal of Astronomy and Space Sciences
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• v.32 no.4
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• pp.311-315
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• 2015

In this study, we estimated the topside scale height of plasma density (Hm) using the Swarm constellation and ionosondes in Korea. The Hm above Korean Peninsula is generally around 50 km. Statistical distributions of the topside scale height exhibited a complex dependence upon local time and season. The results were in general agreement with those of Tulasi Ram et al. (2009), who used the same method to calculate the topside scale height in a mid-latitude region. On the contrary, our results did not fully coincide with those obtained by Liu et al. (2007), who used electron density profiles from Arecibo Incoherent Scatter Radar (ISR) between 1966 and 2002. The disagreement may result from the limitations in our approximation method and data coverage used for estimations, as well as the inherent dependence of Hm on Geographic LONgitude (GLON).

• Journal of the Korean Society of Costume
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• v.50 no.5
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• pp.159-169
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• 2000

The purpose of this study Is to research the clothing and textiles recorded in Heikemonokatary which was written from 1131 to 1198. The research materials are 36 kinds of men's clothes and ornaments, 6 kinds of women's things, 10 kinds of colorings and 6 kinds of textiles. The results of this study are as follow : 1. There were many advanced warriors' clothes. Especially the helmets and armors were very gorgeous. The shapes of warriors' knives, arrows, shields were concretely described. The women's clothes were mostly unchanged from Nara period and Heian period. Women wore clothes on their heads when they went out. 2. One particular thing in color is that the brown color of that period was navy blue which is symbolic of victory. There were some textiles which was woven with the boiled silk thread in the latitude and the raw silk thread in the longitude. Besides, the blackening of teeth, the bobbed haler of boys, and the celebration of one's corning of age were described in the book.