• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5A
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• pp.307-315
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• 2012

Recently, ultra high performance fiber reinforced concrete (UHPFRC) having over 180 MPa compressive strength and 10 MPa tensile strength has been developed in Korea. However, UHPFRC represents different material properties with normal concrete (NC) and conventional high performance concrete (HPC) such as a high early age autogenous shrinkage and a rapid dry on the surface, because it has a low water-binder ratio and high fineness admixtures without coarse aggregate. In this study, therefore, to propose suitable experimental methods and regulations, and to evaluate mechanical properties at a very early age for UHPFRC, setting, shrinkage and tensile tests were performed. From the setting test results, paraffin oil was an appropriate material to prevent drying effect on the surface, because if paraffin oil is applied on the surface, it can efficiently prevent the drying effect and does not disturb or catalyze the hydration of cement. From the ring-test results, it was defined that the shrinkage stress is generated at the time when the graph tendency of temperature and strain of inner steel ring is changed. By comparing with setting test result, the shrinkage stress was firstly occurred as the penetration resistance of 1.5 MPa was obtained, and it was about 0.6 and 2.1 hour faster than those of initial and final sets. So, the starting time of autogenous shrinkage measurement (time-zero) of UHPFRC was determined when the penetration resistance of 1.5 MPa was obtained. Finally, the tensile strength and elastic modulus of UHPFRC were measured from near initial setting time by using a very early age tensile test apparatus, and the prediction models for tensile strength and elastic modulus were proposed.

• Korean Journal of Remote Sensing
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• v.30 no.6
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• pp.809-816
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• 2014

Ocean Color products have been used to understand marine ecosystem. In high latitude region, ice melting optically influences the ocean color products. In this study, we assessed optical properties in fjord around Svalbard Arctic sea, and estimated distribution of chlorophyll-a and suspended sediment by using high resolution satellite data, Landsat-8 Operational Land Imager (OLI). To estimate chlorophyll-a and suspended sediment concentrations, various regression models were tested with different band ratio. The regression models were not shown high correlation because of temporal difference between satellite data and in-situ data. However, model-derived distribution of ocean color products from OLI showed a possibility that fjord and coastal areas around Arctic Sea can be monitored with high resolution satellite data. To understand climate change pattern around Arctic Sea, we need to understand ice meting influences on marine ecosystem change. Results of this study will be used to high resolution monitoring of ice melting and its influences on the marine ecosystem change at high latitude. KOPRI (Korea Polar Research Institute) has been operated the Dasan station on Svalbard since 2002, and study was conducted using Arctic station.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.3_4
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• pp.224-238
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• 2004

Multi-modality image registration is a widely used image processing technique to obtain composite information from two different kinds of image sources. This study proposes an image registration method based on moment information and surface distance, which improves the previous surface-based registration method. The proposed method ensures stable registration results with low registration error without being subject to the initial position and direction of the object. In the preprocessing step, the surface points of the object are extracted, and then moment information is computed based on the surface points. Moment information is matched prior to fine registration based on the surface distance, in order to ensure stable registration results even when the initial positions and directions of the objects are very different. Moreover, surface comer sampling algorithm has been used in extracting representative surface points of the image to overcome the limits of the existed random sampling or systematic sampling methods. The proposed method has been applied to brain MRI(Magnetic Resonance Imaging) and PET(Positron Emission Tomography), and its accuracy and stability were verified through registration error ratio and visual inspection of the 2D/3D registration result images.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.4
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• pp.382-390
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• 2011

Smart sensors embedable in composite wind turbine blades have been required to be researched for monitoring the health status of large wind turbine blades during real-time operation. In this research, the feasibility of packaged FBG sensor probes was studied through the experiments of composite blade trailing edge specimens in order to detect cracking and debonding damages. The instants of cracking and debonding generated in the shear web were confirmed by rapid changes of the wavelength shifts from the bare FBG sensor probes. Packaged FBG sensor probes were proposed to remove the fragile property of bare FBG sensor probes attached on composite wind blade specimens. Strain and temperature sensitivity of fabricated probes installed on the skin of blade specimen were almost equal to those of a bare FBG sensor. Strain sensitivity was measured to be ${\mu}{\varepsilon}$/pm in a strain range from to 0 to 600 ${\mu}{\varepsilon}$, and the calculated temperature sensitivity was to be 48 pm/$^{\circ}C$ in the heating test up to 80 degree.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.692-696
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• 2017

The shape of press components is becoming increasingly complex due to customer demands, process shortening and cost savings. In addition, the stability of the pressing process frequently varies during mass production due to the influence of many factors. In order to ensure the process stability, it is necessary to establish a process in which reproducibility is realized in tolerance, which is sufficient for advance study of shape, material, press, mold and lubrication. However, unforeseen changes in process parameters cause disruptions in production line shutdowns and production planning. In this paper, we introduce a method to monitor a real time process by applying a sensor to a press mold. A non-contact type sensor for measuring the flow of a sheet material and an example of an experiment using the optical sensor which is highly applicable to mass production are presented. An optical sensor was installed in a cylindrical drawing mold to test its potential application while changing the material, blank holder force, and drawing ratio. We also quantitatively determined that the flow of other sheet materials was quantified locally using a square drawing die and that the measured value was always smaller than the drawing depth due to the material elongation. Finally, we propose a field that can be used by attaching the sensor to the press mold. We hope that the consequent cost reduction will contribute to increasing global mold competitiveness.

• Korean Journal of Remote Sensing
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• v.29 no.4
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• pp.361-373
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• 2013

The monitoring of urban area, target detection and building reconstruction have been actively studied and investigated since high resolution X-band SAR images could be acquired by airborne and/or satellite SAR systems. This paper describes an efficient approach to reconstruct artificial structures (e.g. apartment, building and house) in urban area using high resolution X-band SAR images. Building footprint was first extracted from 1:25,000 digital topographic map and then a corner line of building was detected by an automatic detecting algorithm. With SAR amplitude images, an initial building height was calculated by the length of layover estimated using KS-test (Kolmogorov-Smirnov test) from the corner line. The interferometric SAR phases were simulated depending on SAR geometry and changable building heights ranging from -10 m to +10 m of the initial building height. With an interferogram from real SAR data set, the simulation results were compared using the method of the phase consistency. One of results can be finally defined as the reconstructed building height. The developed algorithm was applied to repeat-pass TerraSAR-X spotlight mode data set over an apartment complex in Daejeon city, Korea. The final building heights were validated against reference heights extracted from LiDAR DSM, with an RMSE (Root Mean Square Error) of about 1~2m.

• Journal of Korea Spatial Information System Society
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• v.8 no.2 s.17
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• pp.91-107
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• 2006

To handling the extreme situation that must manage positional information of a very large volume, at least millions of moving objects. A cluster-based sealable distributed computing system architecture, called the GALIS which consists of multiple data processors, each dedicated to keeping records relevant to a different geographical zone and a different time zone, was proposed. In this paper, we proposed a valid time management and time-zone shifting scheme, which are essential in realizing the long-term location data subsystem of GALIS, but missed in our previous prototype development. We explain how to manage valid time of moving objects to avoid ambiguity of location information. We also describe time-zone shifting algorithm with three variations, such as Real Time-Time Zone Shifting, Batch-Time Zone Shifting, Table Partitioned Batch-Time Zone Shifting, Through experiments related with query processing time and CPU utilization, we show the efficiency of the proposed time-zone shifting schemes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.9
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• pp.1228-1236
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• 2018

Recently, the maritime environment contaminated by the abandoned fishing gears. To solve this problem, there requires systematic management techniques for the fishing gears based on ICT technologies. The existed systems are optionally used by owners, but the systems need to adopt the monitoring and control architecture for integrated national surveillance. To do this, we designed an architecture for effective monitoring and management which collects position and state information using automatic identification buoy (AIB) device, to send the fishing ship, administrator ship, and shore side control center based on the IoT networks. Especially, in this paper, we developed the ENC-based integrated control system for efficient management which provides functions for position indication, state information display and loss alarm of fishing gears. Also, we conduct performance tests for data processing and visualization functions of the system to use a virtual buoy generation module.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.190-193
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• 2015

The current sea route sign system based on an electronic marine chart only has a data manufacture specification for uses at ECDIS. Therefore, it has a limitation in expressing various sea route data and falls short of productivity as it is frozen to prevent being changed for a long time. Also, it cannot satisfy requirements from high tech such as lattice structure data and time series information. Currently, although it builds each independent operation system based S-57, it has been found that it is the most important requirement from consumers that the entire monitoring system can mutually interwork by standardizing and uniting formats of all protocols. In addition, current status information and alarm system is using AIS, TRS, WCDMA telecommunication and processing all the data after saving it into each different server. Lighthouse lantern which currently has used was utilized to do a performance test of a developed system. All of created data was trasmitted through the RS-232, It is clear that the data was received by a situation monitoring system. In addition, when the data was transmitted after saving in a database, same data was ordinarily received. In this thesis, we will implemented the status information and alarm system of Marine transportation facilities which is a sea route sign system based on S-63 electronic marine chart, S/W, after uniting each different protocol and making combined system.

• Korean Journal of Materials Research
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• v.11 no.3
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• pp.197-202
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• 2001

M $g_{1-x}$ Z $n_{x}$O thin films with various composition x of ZnO were fabricated by a RF magnetron sputtering method, which is expected to improve the electro-optical properties of the conventional MgO protective layer for AC-PDP. Test panels with the $Mg_{1-x}$Z $n_{x}$O protective layer have been fabricated in order to investigate the effects of ZnO doping on the electrical characteristics of devices such as the discharge voltages and the memory gain. Experimental results revealed that test panels with the $Mg_{1-x}$Z $n_{x}$O(x=0.5at%) protective layer show lower firing and sustain voltages than those seen in panels with MgO protective layer by 20V. resulting in an increasement of the memory coefficient. In addition, it was found that test panels with the $Mg_{1-x}$Z $n_{x}$O protective layer show higher discharge intensity, i. e., higher plasma density, compared with panels with MgO protective layer.ve layer.layer.