• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.15 no.2
• /
• pp.231-236
• /
• 1997

Observation for hot water spread has been carried out by such activites as sampling of water with ship, etc, until now It was required further to have new probe methodologies in such issues as simultaneity, great-spheric nature, and economics due to many hindering ele- ments such as spread speed of hot waste water, weather conditions, cost and expenses, scope and location determinations. However, it was believed that satellite could be utilized to monitor spread of water temperature and spread level in more quick and correct way than existing one, because it would be possible to supervise and detect marine environment within significantly short period if analyzed by means of satellite images. Therefore, this study is taken into account to flow and spread conditions of hot waste water, survey of water temperature, by means of satellite images.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2010.04a
• /
• pp.333-335
• /
• 2010

Global warming gas caused an increase in a direct and indirect problems like the rising sea level, seawater overflowing and a coastal flooding. The loss and damage of the republic of korea are increasing because of the rising sea level. As a result, It is necessary to establish the foundation of the monitoring of the sea level changes for the flooding prevention. A new measurement technique is developed using GPS equipped ship to make up for the spatial-temporal and economical problems by this study. We compared the data using GPS with the value for height of the tide. And we corrected the errors using the more accurate data that we studied. In addition to we studied that the corrected value had statistical significance and similarity compared with the observed value using GPS. The following studies also performed : When the observed value of tide by a tide observatory and by using GPS are applied to sounding ; How the values of the water depth are being, and if the values are similar, whether the observed value of tide using GPS is valid or not.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.32 no.6
• /
• pp.553-560
• /
• 2020

This paper presents an algorithm for identifying and eliminating errors by seagrasses in coastal bathymetry surveying using drone and HD camera. Survey errors due to seagrasses were identified, segmentated and eliminated using a L∗a∗b color space model. Bathymetry survey using a drone and HD camera has many advantages over conventional survey methods such as ship-board acoustic sounder or manual level survey which are time consuming and expensive. However, errors caused by sea bed reflectance due to seagrasses habitat hamper the development of new surveying tool. Seagrasses are the flowering plants which start to grow in November and flourish to maximum density until April in Korea. We developed a new algorithm for identifying seagrasses habitat locations and eliminating errors due to seagrasses to get the accurate depth survey data. We tested our algorithm at Wolpo beach. Bathymetry survey data which were obtained using a drone with HD camera and calibrated to eliminate errors due to seagrasses, were compared with depth survey data obtained using ship-board multi-beam acoustic sounder. The abnormal bathymetry data which are defined as the excess of 1.5 times of a standard deviation of random errors, are composed of 8.6% of the test site of area of 200 m by 300 m. By applying the developed algorithm, 92% of abnnormal bathymetry data were successfully eliminated and 33% of RMS errors were reduced.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.29 no.6
• /
• pp.613-620
• /
• 2011

In order to perform scientific evaluation of dredge results, it is needed to construct the system which is able to manage and evaluate the work process by monitoring in real-time the dredge process such as dredge ship position, dredge depth and dredge volume. This research aims to develop the hydrographic dredge surveying system adding water depth measurement method to both precise positioning and navigation methods using GPS, which allows a high rate of measurement and long distances between the control point and dredging points, operate in all weather conditions, and does not require line of sight to points. We constructed Beacon DGPS-based hydrographic dredger guidance and position management system and developed the operation program which makes the dredge operation perform as monitoring work situation in real-time. It is expected that this developed system will be able to contributes to reducing ultimately the cost in hydrographic dredging or hydrographic construction industries.

• Korean Journal of Remote Sensing
• /
• v.34 no.2_2
• /
• pp.393-406
• /
• 2018

Every year in the ocean, various accidents occur frequently and illegal fishing is rampant. Moreover, their size and frequency are also increasing. In order to reduce losses of life or property caused by these, it is necessary to have a means to perform remote monitoring quickly. As an effective platform of such monitoring means, an Unmanned Aerial Vehicle (UAV) is receiving the spotlight. In these situations where marine accidents or illegal fishing occur, main targets of monitoring are ships. In this study, we propose a UAV based ship monitoring system and suggest a method of determining ship positions using UAV multi-sensory data. In the proposed method, firstly, the position and attitude of individual images are determined by using the pre-performed system calibration results and GPS/INS data obtained at the time when images were acquired. In addition, after the ship being detected automatically or semi-automatically from the individual images, the absolute coordinates of the detected ships are determined. The proposed method was applied to actual data measured at 200 m, 350 m, and 500 m altitude, the ship position can be determined with accuracy of 4.068 m, 8.916 m, and 13.734 m, respectively. According to the minimum standard of a hydrographical survey, the ship positioning results of 200 m and 350 m data satisfy grade S and the results of 500 m data do grade 1a, where the accuracy is required for positioning the coastline and topography less significant to navigation order. Therefore, it is expected that the proposed method can be effectively used for various purposes of marine monitoring or surveying.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.14 no.2
• /
• pp.127-139
• /
• 1996

This paper presents a procedure to recover sea surface heights (SSH) and free-air (FA) gravity anomalies from dense satellite altimeter SSH data with enhanced accuracies over the full spectrum of the gravity field. A wavenumber correlation filtering (WCF) of co-linear SSH tracks is developed for the coherent signals of sub-surface geological masses. Orbital cross-over adjustments with bias parameters are applied to the filtered SSH data, which are then separated into two groups of ascending and descending tracks and gridded with tensioned splines. A directional sensitive filter (DSF) is developed to reduce residual errors in the orbital adjustments that appear as track patterned SSH. Finally, FA gravity anomalies can be obtained by the application of a gradient filter on a high resolution estimate of geoid undulations after subtracting dynamic sea surface topography (DSST) from the SSH. These procedures are applied to the Geosat Geodetic Mission (GM) data of the southern oceans in a test area of ca. $900km\;\times{1,200}\;km$ to resolve geoid undulations and FA gravity anomalies to wavelengths of-10 km and larger. Comparisons with gravity data from ship surveys, predictions by least squares collocation (LSC), and 2 versions of NOAA's predictions using vertical deflections illustrate the performance of this procedure for recovering all elements of the gravity spectrum. Statistics on differences between precise ship data and predicted FA gravity anomalies show a mean of 0.1 mgal, an RMS of 3.5 mgal, maximum differences of 10. 2 mgal and -18.6 mgal, and a correlation coefficient of 0.993 over four straight ship tracks of ca. 1,600 km where gravity changes over 150 mgals.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.22 no.3
• /
• pp.1-9
• /
• 2019

In the recent marine sector, the development and standardization regarding S-100, which is the universal hydrographical data model standard for development of marine space information, was progressed, and for the effectiveness of marine chart production work and the multi-purpose use of water level data in S-100, S-102(Bathymetric Surface grid) standard development and various studies of BAG formats combined with water level and uncertainty, property information is being progressed. Since the water level information that is important in the operation of the ship is provided based on S-102, the calibration method of the location information when producing S-102 is an important factor in deciding the water level. In this study, the hydrographical surveying was conducted by piloting the standardized method for the production of S-102 in Korea, and have compared the accuracy of water level information according to the GNSS post treatment calibration method. As a result of comparing the water level in 2 places in the rocky terrain of the study area, the northern water level of Namu-do was shown as DL 0.79~0.83m, the eastern water level of Daeho-do was DL 12.63~12.91m, and the horizontal position errors of the intermittent sunshine water level were confirmed to be within 1m. As a result, the intermittent sunshine water level according to the location calibration method when producing the BAG was confirmed that it was in the available range for a ship's safe voyage. However, the accuracy verification for the location of the ship when conducting hydrographical surveying was judged that there is a need for a various additional study about regional characteristics and environment factor.

• Journal of the Korean Institute of Navigation
• /
• v.19 no.4
• /
• pp.1-8
• /
• 1995

Although ship's draught information onboard is substantial for both the safety of navigation and the estimation of loaded cargoes, its accuracy depends, in conventional surveying method, on the skillfulness of observers and the condition of the sea surface round the vessel. To obtain more accurate information accessibly, measuring instruments with sophisticated sensors such as mechanical, electronic and ultrasonic transducers have been developed. However, they have still limitation in accuracy and in making up a system due to the complexity of processing signal. In this paper, we propose a new technique for analyzing ultrasonic pulse signal, in order to improve the measurement accuracy and simplify a remote sensing system of draught by ultrasonic waves. In this technique, pulse signal is translated into phase curve which is composed of the phase value defined in time domain. Then, the time interval between two signals different in waveform, is waveform, is analytically determined by calculating average time difference on phase curves. Also, analytical procedure can be carried out in real time with the successive five data sampled at T/4, for high speed digital processing with computer and A/D converter. This technique is useful for measuring draught under the influence of sea condition and for interfacing its data briefly to the integrated bridge system.

• Journal of Korean Society for Geospatial Information Science
• /
• v.21 no.4
• /
• pp.3-12
• /
• 2013

In order to evaluate dredging results scientifically the system which can manage and estimate working process by monitoring dredging process in real-time needs to be constructed. We constructed real-time dredging management system for guidance of a dredging vessel and for survey of dredging construction. This system was designed to have functions of dredger location by GPS, ship direction measurement by GPS/Gyroscope combination, Grab position measurement, dredging depth measurement and correction. In addition, we developed the programs for controlling and operating the constructed system. The system could induce the vessel to accurate position and conduct dredging according to plan and the effectiveness of the system was evaluated through the results of application to actual dredging construction site.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.16 no.1
• /
• pp.39-46
• /
• 2004

In the GIS construction to land and sea in Korea, GIS construction on land was completed mostly for big cities by NGIS(National Geography Information System) business. However, Marine GIS being constructed by the National Oceanographic Research Institute is still constructing geography information and definition of attribute information and real condition. We have done researches to get maximized ripple effect linking GPS and Navigation techniques on GIS. GPS in accuracy is divided into navigation and precise surveying equipments. Now, GPS technology has been developed very much and with low price GPS equipments are being introduced. But costs on the GPS equipments are high yet. Therefore, the GPS equipments for navigation can be substituted by cheap GPS equipments in a car or ship. In this paper, the authors developed algorithm to convert ellipsoid coordinate between WGS84 and Bessel ellipsoid and to analyze map projection between BESSEL ellipsoid and UTM plane coordinate system. And the author developed ship navigation system with cheap GPS equipments using algorithm of ellipsoid conversion and map projection. The authors proposed the necessity on constructing Internet GIS to manage many ships.