• The Journal of the Acoustical Society of Korea
• /
• v.34 no.3
• /
• pp.200-209
• /
• 2015

An underwater sound surveillance system detects and tracks enemy ships in real-time using hydrophone arrays, in which seabed-mounted sensor arrays play a pivotal role. In this paper the conceptual design of seabed-mounted, cylindrical hydrophone arrays for use in shallow coastal waters is performed via finite element calculations. To stabilize the receiving characteristics under the ocean ambient noise, a technique for whitening the ambient noise spectrum using a metal baffle is proposed. Optimization of the array configuration is performed to achieve the directivity in the vertical and azimuthal directions. And the effects of the sonar dome shape and material on the structural vibration and sound scattering properties are studied. It is demonstrated that a robust hydrophone array, having a sensitivity deviation less than 4 dB over the frequency range of interest, can be obtained through the whitening of the ambient noise, the optimization of the array configuration, and the design of acoustically transparent sonar domes.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.11
• /
• pp.907-914
• /
• 2014

The objective of this study was to increase the generating efficiency of concentrated photovoltaics (CPV) by using hybrid solar tracking. Further, the proposed system was demonstrated to have the ability to extract thermal energy from a concentrated photovoltaic system by using thermal absorbers containing heat pipe, which could then be used for a heating system or hot-water supply. The average electrical efficiency was 16 during the day, and the average thermal efficiency was 62. Therefore, this system demonstrated a total efficiency (electrical thermal) of 78. All the processes, i.e., tracking of the sun, calculation of the sun's position, reinstatement of the heating device toward the east for tracking on the next day, and system shutdown, were programmed using Simulink. A parametric analysis of the heat pipe, concentration ratio, and inlet velocity was also performed in terms of the operating temperature of the CPV and the outlet temperature. The simulation and experimental results for the thermal absorber were found to be in good agreement.

• Proceedings of the Korea Contents Association Conference
• /
• 2007.11a
• /
• pp.27-29
• /
• 2007

The visual implementation of 3-dimensional national environment is focused by the requirement and importance in the fields such as, national development plan, telecommunication facility deployment plan, railway construction, construction engineering, spatial city development, safety and disaster prevention engineering. The currently used DEM system using contour lines, which embodies national geographic information based on the 2-D digital maps and facility information has limitation in implementation in reproducing the 3-D spatial city. Moreover, this method often neglects the altitude of the rail way infrastructure which has narrow width and long length. There it is needed to apply laser measurement technique in the spatial target object to obtain accuracy. Currently, the LiDAR data which combines the laser measurement skill and GPS has been introduced to obtain high resolution accuracy in the altitude measurement. In this paper, we first investigate the LiDAR based researches in advanced foreign countries, then we propose data a generation scheme and an algorithm for the optimal manage and synthesis of railway facility system in our 3-D spatial terrain information. For this object, LiDAR based height data transformed to DEM, and the realtime unification of the vector via digital image mapping and raster via exactness evaluation is transformed to make it possible to trace the model of generated 3-dimensional railway model with long distance for 3D tract model generation.

• Fire Science and Engineering
• /
• v.30 no.6
• /
• pp.92-98
• /
• 2016

This study evaluated thermal image real-time estimation and fire alarm using by a CCD camera, which has been a seamless feature-point analysis method, according to the angle and position and image fusion by a vector coordinate point set-up of equal shape. The system has higher accuracy, fixing data value of temperature sensing and fire image of 0~255, and sensor output-value of 0~5,000. The operation time of a flame specimen within 500 m, 1000 m, and 1500 m from the test report specimen took 7 s, 26 s, and 62 s, respectively, and image creation was proven. A diagnosis of fire accident was designated to 3 steps: Caution/Alarm/Fire. Therefore, a series of process and the transmission of SNS were identified. A light bulb and fluorescent bulb were also tested for a false alarm test, but no false alarm occurred. The possibility that an unwanted alarm will be reduced was verified through a forecast of the fire progress or real-time estimation of a thermal image by the change in the image of a time-based flame and an analysis of the diffusion velocity.

• International Journal of Highway Engineering
• /
• v.12 no.4
• /
• pp.157-164
• /
• 2010

This research was conducted to analyze the behavior of Single-PTAS (Single Post-Tensioned Approach Slab) under tensioning and environmental loads by performing field tests when the demonstration Single-PTAS was being constructed. The temperature measurement sensors were installed at different depths, and the displacements in the approach slab under environmental loads and tensioning were measured using displacement transducers. As an experimental result, an abrupt change in the longitudinal displacement due to tensioning was not observed. The daily temperature change in the approach slab was negligible where the depth is over about 35cm. The temperature gradient in the approach slab adjacent to bridge was smaller than that adjacent to pavement. The patterns and magnitudes of vertical displacements were directly related to the temperature gradient at the measuring location. The behavior of Single-PTAS was very similar to that of concrete pavement. Therefore, a new design methodology for approach slabs is needed to include the pavement concept and to overcome drawback of current design procedures based on the simple beam concept.

• Korean Journal of Remote Sensing
• /
• v.39 no.5_3
• /
• pp.885-890
• /
• 2023

As satellite technology progresses, a growing number of satellites-like CubeSat and radar satellites-are available with a higher spectral and spatial resolutions than previous. National initiatives used to be the main force behind satellite development, but current trendsindicate that private enterprises are also actively exploring and developing new satellite technologies. This special issue examines the recent research results and advanced technology in remote sensing approaches for Earth environment analysis. These results provide important information for the development of satellite sensors in the future and are of great interest to researchers working with artificial intelligence in thisfield. The special issue introduces the latest advances in remote sensing technology and highlights studies that make use of data to monitor and forecast Earth's environment. The objective is to provide direction for the future of remote sensing research.

• Journal of Korean Society of Disaster and Security
• /
• v.6 no.3
• /
• pp.9-17
• /
• 2013

Geospatial information data came recently in use to build the location-based service in various fields. These data were shown via a 2-D map in the past but now can be viewed as a 3-D map due to the dramatic evolution of IT technology, thus improving efficiency and raising practicality to a greater extent by providing a more realistic visualization of the field. In addition, many previous GIS applications have been provided under desktop environment, limiting access from remote sites and reducing its approachability for less experienced users. The latest trend offers service with web-based environment, providing efficient sharing of data to all users, both unknown and specific internal users. Therefore, real-time information sensors that have been installed on steep slopes are to be integrated with 3-D geospatial information in this study. It is also to be developed with web-based environment to improve usage and access. There are three steps taken to establish this system: firstly, a 3-D GIS database and 3-D terrain with higher resolution aerial photos and DEM (Digital Elevation Model) have been built; secondly, a system architecture was proposed to integrate real-time sensor information data with 3D Web-based GIS; thirdly, the system has been constructed for Gangwon Province as a test bed to verify the applicability.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.10
• /
• pp.36-41
• /
• 2017

The mobile mapping system first introduced at Ohio State University in 1991 is being developed in various forms as sensor technology develops. The mobile mapping system can acquire geospatial information around amoving object quickly using the information gathered using the position and attitude information of the moving object and the data from various sensors. The mobile mapping system can rapidly acquire large amounts of Geospatial information and MMS provides maximum productivity in the same measurement methods as existing GNSS and total stations. Currently, a variety of systems are being launched, mainly by foreign companies, and they are applied to the construction of geospatial information. On the other hand, the application of domestic technology development or production is insufficient. This paper provides basic data for the introduction of a mobile mapping system to geospatial information related business by conducting the status survey and feature analysis of a commercialized system focusing on the ground-based mobile mapping system. The research identified the current status and characteristics of high-priced, low-priced, indoor, and handheld mobile mapping systems based on vehicles and suggest that the recent system development trends are moving toward lowering the unit prices. The mobile mapping system is currently being developed as a platform for the application of geospatial information construction and the launch of low-cost models. The development of data processing technologies, such as automatic matching and the launch of low-cost models, are forming a basis for the application of mobile mapping systems in the field of geospatial information construction.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.20 no.6
• /
• pp.101-107
• /
• 2020

Road surface measurement is an essential process for quantifying the degree and displacement of roughness in road surface management. For safer road surface management and quick maintenance, it is important to accurately measure the road surface while mounted on a vehicle. In this paper, we propose a sophisticated road surface measurement system that can be measured on a moving vehicle. The proposed road surface measurement system supports more accurate measurement of the road surface by using a high-performance line laser sensor. It is also possible to measure the transverse and longitudinal profile by matching the position information acquired from the RTK, and the velocity adaptive update algorithm allows a manager to monitor in a real-time manner. In order to evaluate the proposed system, the Gocator laser sensor, MRP module, and NVIDIA Xavier processor were mounted on a test mobile and tested on the road surface. Our evaluation results demonstrate that our system measures accurate profile base on the MSE. Our proposed system can be used not only for evaluating the condition of roads but also for evaluating the impact of adjacent excavation.

• Korean Journal of Remote Sensing
• /
• v.38 no.6_4
• /
• pp.1879-1887
• /
• 2022

In this study, a method of estimating the velocity and altitude of aircrafts photographed in a KOMPSAT-3 satellite was proposed. In the proposed method, parallax effect, which is a time offset between bands due to the photographing method of the KOMPSAT-3 satellite, the structure of the sensor, and the movement of the satellite's orbit, was calculated, and in this process, trucks running on the highway were used. In addition, the actual direction and the direction by parallax effect of the aircraft were calculated using the coordinates of the aircraft in the image, and the attitude information of the KOMPSAT-3 satellite was calculated using metadata to estimate the velocity and altitude of the aircraft. The estimated value through the proposed method was compared with the actual value, automatic dependent surveillance-broadcast (ADS-B), and the error rate was calculated here. As a result, it was confirmed that the velocity and altitude error rate of large aircraft (I1, I3, S2) were lower than that of light aircraft (I2, S2), and the estimated velocity and altitude were relatively high in large aircraft using the proposed method.