• Journal of Korean Society for Geospatial Information Science
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• v.25 no.1
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• pp.47-54
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• 2017

Recently, there are many studies related aerial mapping project and 3 dimensional shape and model reconstruction using UAV(unmanned aerial vehicle) system and images. In this study, we create 3D reconstruction point data using image matching technology of the UAV overlap images, detect shape change of structure and perform accuracy assessment of area($m^2$) and volume($m^3$) value. First, we build the test structure model data and capturing its images of shape change Before and After. Second, for post-processing the Before dataset is convert the form of raster format image to ensure the compare with all 3D point clouds of the After dataset. The result shows high accuracy in the shape change of more than 30 centimeters, but less is still it becomes difficult to apply because of image matching technology has its own limits. But proposed methodology seems very useful to detect illegal any structures and the quantitative analysis of the structure's a certain amount of damage and management.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.5
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• pp.465-471
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• 2013

A steam generator in nuclear power plant is a heatexchager which is used to convert water into steam from heat produced in a nuclear reactor core, and the steam produced in steam generator is delivered to the turbine to generate electricity. Because of damage to steam generator tubing may impair its ability to adequately perform required safety functions in terms of both structural integrity and leakage integrity, eddy current testing is periodically performed to evaluate the integrity of tubes in steam generator. This assessment is normally performed during a reactor refueling outage. Currently, the eddy current testing for steam generator of nuclear power plant in Korea is performed in accordance with KEPIC & ASME Code requirements, the eddy current testing system is consists of remote data acquisition unit and data analysis program to evaluate the acquired data. The KEPIC & ASME Code require that the electrical properties of remote data acquisition unit, such as total harmonic distortion, input & output impedance, amplifier linearity & stability, phase linearity, bandwidth & demodulation filter response, analog-to-digital conversion, and channel crosstalk shall be measured in accordance with the KEPIC & ASME Code requirements. In this paper, the measurement requirements of electrical properties for eddy current testing instrument described in KEPIC & ASME Code are presented, and the measurement results of newly developed eddy current testing instrument by KHNP(Korea Hydro & Nuclear Power Co., LTD) are presented.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.135-143
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• 2009

The Manila clam, Ruditapes philippinarum, has been considered as a sentinel species due to dominant distribution along the coast of Korea and well developed regulatory system. In order to develop and understand immune responses of the Manila clams, clams were exposed to $50\;{\mu}g/L$ of cadmium chloride (Cd) for 8 days and monitored the cellular immune parameters of the hemocytes including blast cell composition, DNA damage, necrosis, apoptosis and hemocyte mortality using a flow cytometer. The results showed that all immune parameters analyzed in the present study increased remarkably compared to the controls and the increases were statistically significant. Apoptosis rate was higher than necrosis rate in the clams exposed to Cd suggesting that apoptosis was preferably induced by the concentration of Cd used in the present study. Our study indicates that the measurement of cellular immune responses of the Manila clam using flow cytometer will be a useful technique for assessment of heavy metal contamination in marine environment.

• Smart Structures and Systems
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• v.10 no.2
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• pp.131-154
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• 2012

In this paper, it is aimed to determine the seismic behaviour of highway bridges by nondestructive testing using ambient vibration measurements. Eynel Highway Bridge which has arch type structural system with a total length of 216 m and located in the Ayvaclk county of Samsun, Turkey is selected as an application. The bridge connects the villages which are separated with Suat U$\breve{g}$urlu Dam Lake. A three dimensional finite element model is first established for a highway bridge using project drawings and an analytical modal analysis is then performed to generate natural frequencies and mode shapes in the three orthogonal directions. The ambient vibration measurements are carried out on the bridge deck under natural excitation such as traffic, human walking and wind loads using Operational Modal Analysis. Sensitive seismic accelerometers are used to collect signals obtained from the experimental tests. To obtain experimental dynamic characteristics, two output-only system identification techniques are employed namely, Enhanced Frequency Domain Decomposition technique in the frequency domain and Stochastic Subspace Identification technique in time domain. Analytical and experimental dynamic characteristic are compared with each other and finite element model of the bridge is updated by changing of boundary conditions to reduce the differences between the results. It is demonstrated that the ambient vibration measurements are enough to identify the most significant modes of highway bridges. After finite element model updating, maximum differences between the natural frequencies are reduced averagely from 23% to 3%. The updated finite element model reflects the dynamic characteristics of the bridge better, and it can be used to predict the dynamic response under complex external forces. It is also helpful for further damage identification and health condition monitoring. Analytical model of the bridge before and after model updating is analyzed using 1992 Erzincan earthquake record to determine the seismic behaviour. It can be seen from the analysis results that displacements increase by the height of bridge columns and along to middle point of the deck and main arches. Bending moments have an increasing trend along to first and last 50 m and have a decreasing trend long to the middle of the main arches.

• Journal of the Korea Society of Computer and Information
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• v.24 no.12
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• pp.157-166
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• 2019

Globally, various disasters such as typhoons, floods, earthquakes, fires, explosions have caused work to be halted. If there is a large-scale disaster at public institutions in charge of major national affairs and their works are interrupted, not only will there be property damage, but there will also lead to a decline in national credibility and direct and indirect impacts on the people. Therefore, it is necessary to ensure continuity of operation by minimizing the interruption period of critical operations due to disasters. Overseas advanced countries such as the United States and Japan developed guidelines for Continuity of Operation (COOP) to prevent unexpected work disruptions caused by disasters. Recognizing the necessity of COOP in South Korea, a relevant law has been newly established in 「the Framework Act on the Management of Disasters and Safety」 to enable public institutions to establish the COOP in response to this situation. In this study, the definition, the necessity and overseas cases of COOP were investigated and described. Using the templates developed by these results, operational impact analysis, risk assessment, operational continuity strategies and operational continuity procedures were applied to "A" City Hall in Gyeonggi-do province and those results were described. The objective of this study is to substantially contribute to the introduction of COOP to local governments through their pilot application and implications of COOP.

• Korean Journal of Environment and Ecology
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• v.30 no.4
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• pp.712-723
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• 2016

This paper is to suggest the methods about the environmental risk assessment (ERA) based on non-target insect species for LM rice crop produced by biotechnology. We used some data by the picture dictionary of agricultural pests in Korea, some books for ERA or rice pest ecology, articles about rice ecology, and internet sites and many specialists gave us good advice for this ERA system. We found about 140 insect species using rice crop as their habitat and we discriminated herbivores into Sap feeder, Grain feeder, Defoliator, and Pollen feeder according to their food functional group. We also clarified the potential damage possibility of insect species from LM rice crop. Then, we ranked 10 non-target insect species (Baliothrips biformis, Laodelphax striatellus, Nilaparvata lugens, Mythimna separata, Cnaphalocrocis medinalis, Cletus schmidti Kiritshenko, Scotinophara lurida, Nilaparvata bakeri, Oxya chinensis, Agromyza oryzae) with giving some scores using Geographic distribution, Habitat specialization, Prevalence on crop, Abundance. We showed some environmental risk hypotheses about herbivore, predator, and parasitoid, and infered the impacts of non-target species on LM rice crop. Conclusively, we want to serve this methodology to build the biosafety system from biotechnology crops, and the methodology is to keep public health, sustain the biodiversity, and conserve the natural ecosystems.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.2
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• pp.165-172
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• 2013

Power generating unit structures are designed and built to meet standard to secure its safety for expected life time. As the structures have been exposed to combined environment, degradation of structure material is accelerated and it can cause unexpected damage; evaluating precise mechanical properties of weak site like welded area is an essential research area as it is directly connected to safety issues. Existing measuring technique like tensile test requires specific size in testing specimen yet it is destructive method which is hard to apply on running structures. To overcome above mentioned limitation, IIT is getting limelight as it is non-destructive and simple method. In this study, latest technique is introduced to evaluate tensile property and residual stress by analyzing stress field occurs under the indenter while IIT is performed. Test on welded area, the weak site of nuclear structures have been practiced and confirmed that IIT can be usefully applied to evaluate integrity in industry.

• Geotechnical Engineering
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• v.14 no.5
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• pp.205-218
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• 1998

The purpose of this study is to develop and utilize new assessment of liquefaction potential based on DSC(disturbed state concept) and dissipated energy concept. The term liquefaction has suddenly loses its shear strength and behaves like a fluid. Liquefaction has been a source of a major damage during severe earthquake. In this study, the cyclic undrained behavior of Joomoonjin strand is investigated by using an automates triaxial testing device(C. K. Chan type). In order to assess liquefaction potential of saturated strand, DSC method and energy method are applied for the experimental data. The use of DSC method and energy method to define the liquefaction potential is verified through laboratory testis of cyclic triaxial test on saturated sand specimens. Based on the analytical results of DSC method, the relationship between the factor affecting liquefaction characteristics(Dr) and physical properties of the saturated santa(fs and D.) is found. Based on the analytical results of energy method, it is found that the initial liquefaction of rand is related to the significant change in the dissipated energy. Finally, it is shown that the DSC method and energy method can capture the liquefaction mechanism.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.3
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• pp.257-268
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• 2018

We have studied the damage mechanism of a metallic thin plate by the highly energetic fragments generated from high explosive(HE) warhead. The penetration process has presumed that the velocity of a fragment is in the range of 350 m/s to 3353 m/s, the thickness of Aluminum 2024 target plate is in the range of 1 mm~6.3 mm thick. The mass of fragment with hemisphere nose shape is in the range of 0.32 g to 16 g. The analytical solution for penetration process has been derived by using the report of the project THOR. The results of analysis implied that the closed forms by an exponentially decay function well fit the change of the ballistic limit velocity, loss velocity and loss mass of fragment as the mass of fragment and the thickness of target plate increase.

• Journal of Korea Water Resources Association
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• v.47 no.12
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• pp.1187-1198
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• 2014

Strong winds and heavy rainfall from tropical cyclones (TCs) that occur in the Northwestern Pacific cause significant human and material damage to the Korean peninsula and East Asia. Hence, it is important to establish early warning systems and conduct preparedness activities in advance of a TC. This study suggests a technique to extract the value of uniform TC-induced rainfall considering the TC track and TC size. To validate our technique, we compare it to existing TC rainfall techniques using the spatial domain. To determine the TC size required for extracting TC-induced rainfall, this research analyzed the mean of TC-induced rainfall by TC size (1973-2012). As a result of this analysis, the maximum amount of mean of TC-induced rainfall was found for a TC with a radius of 700 km. Other techniques have limitations which this new technique addresses; it can extract TC-induced rainfall in each administrative area and minimize systematic biases of other extraction methods. The result of this study can be utilized in the preparation of rainfall forecasts, designing hydraulic structures, and predicting landslide and debris flows using TC-induced rainfall and downpours.