• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.3
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• pp.311-320
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• 2008

A LIDAR can rapidly generate 3D points by densely sampling the surfaces of targets using laser pulses, which has been efficiently utilized to reconstruct 3D models of the targets automatically. Due to this advantage, LIDARs are increasingly applied to the fields of Defense and Security, for examples, being employed to intelligently guided missiles and manned/unmanned reconnaissance planes. For the prior verification of the LIDAR applicability, this study aims at generating simulated LIDAR data. Here, we derived the sensor equation by modelling the geometric relationships between the LIDAR sub-modules, such as GPS, IMU, LS and the systematic errors associated with them. Based on this equation, we developed a program to generate simulated data with the system parameters, the systematic errors, the flight trajectories and attitudes, and the reference terrain model given. This program had been applied to generating simulated LIDAR data for urban areas. By analyzing these simulated data, we verified the accuracy and usefulness of the simulation. The simulator developed in this study will provide economically various test data required for the development of application algorithms and contribute to the optimal establishment of the flight and system parameters.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.9
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• pp.745-751
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• 2014

For the multi-nozzle propulsion, the rupture pressure of nozzle closure has an effect on the initial strain rate of ignition. Moreover, the deviation of rupture pressure for each nozzle closure leads to side forces which can disturb the attitude control of rocket. When designed, it should be considered whether nozzle closures are ruptured equally and exactly in the intented pressure. In this paper, the rupture behavior is analyzed by analytical and experimental methods for plate and "+" notched nozzle closures. The rupture pressure and deviation for operating temperature, whether notched or not and notched directions are analyzed. This paper provides a comparison between rupture pressure prediction of finite elements method which tool is Abaqus/Explicit and results of the rupture test. Jonson-Cook shear failure model which corresponds to the damage initiation criterion were used in this simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5654-5663
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• 2015

In the unsaturated soil, suction, the negative pore water pressure leads to increases of the yield stress and the plastic shear stiffness of the soil skeleton due to the growth in interparticle stress. Therefore, in this study, the stress-strain relationship based on cyclic elasto-plastic constitutive model extended for unsaturated soil considering the 1st and the 2nd yield functions was induced in order to account for these effects of suction under the dynamic loading condition such as the earthquake. Through the program code considering this relationship and the routine of the cyclic loading with the reversion of loading direction, the numerical simulation of the cyclic triaxial test under the unsaturated condition would be possible. It is expected that the results of this study possibly contribute to the accuracy improvement on the prediction of unsaturated soil behavior under the dynamic loading condition.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.1
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• pp.72-78
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• 2015

Recently, the usage of the satellite is increased more and more in the areas that are communication, weather, marine, optical, radar etc. The functions of the Satellite are evolving from passive transponder to active transponder by the developing of a technology. Advanced countries in satellites install the DCAMP for increase of bandwidth efficiency, improvement of QoS by interference rejection. DCAMP includes many digital components in order to implement functions. Thus, these kinds of active transponders consume much more power compared to passive transponder and then increase the heat. In this paper, we discuss the TVAC test result of DCAMP in EQM(Engineering Qualification Model) level. The paper shows the test results of digital gain control in order to verify DCAMP status under the TVAC test. In addition, the temperature and heat condition of main components from viewpoint of derating will be treated through the official environment test for qualification.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.410-415
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• 2001

Earned Value Management System(EVMS) has been considered as a useful tool of managing construction projects lately and its instruction into a private industry is now under consideration by the Korean government. It is on the basis of C/SCSC that had been released by the U.S. Department of Defense(DOD) since 1967. Its research has been in the active progress in order to utilize the earned value concept as a project management tool for construction project ordered by both government and private sector. Material Requirement Planning(MRP) is also known as a tool of planning and scheduling resources for assembly product as a part of inventory control models in the manufacturing industry. The purpose of this study is the effective employment of Earned Value Management to manage the construction projects by utilizing Material Requirement Planning(MRP), based on project management software and Workpackaging model.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.3
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• pp.62-69
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• 2014

This paper presents a preliminary study of a convergent divergent nozzle in an afterburning turbofan engine of a supersonic aircraft engine. In order to design a convergent divergent nozzle, cycle model of a low bypass afterburning turbofan engine of which thrust class is 29,000 lbf at a sea level static condition is established. The cycle analysis at the design point is conducted by Gasturb 12 software and one dimensional gas properties at a downstream direction of the turbine are obtained. The dimension and configuration of an model turbofan engine are derived from take-off operation with wet reheat condition. The off-design cycle calculation is conducted at the all flight envelope on the maximum flight Mach number of 2.0 and maximum flight altitude of 15,000 m.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.5
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• pp.381-387
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• 2017

Fiber-reinforced composites not only have a direction of thermal expansion coefficient, but also inevitably suffer thermal stress effects due to the difference between the manufacturing process temperature and the actual use temperature. The damage caused by thermal stress is more prominent in the case of thick composite laminates, which are increasingly applied in the aerospace industry, and have a great influence on the mechanical function and fracture strength of the laminates. In this study, the dimensional reduction and thermal stress recovery theory of composite beam structure having high slenderness ratio is introduced and show the efficiency and accuracy of the thermal stress comparison results between the 3-D finite element model and the dimension reduction beam model. Efficient recovery analysis study will be introduced by reconstructing the thermal stress of the composite beam section applied to the thermal environment by constructing the dimensional reduction modeling and recovery relations.

• Journal of Ginseng Research
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• v.42 no.4
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• pp.436-446
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• 2018

Background: The potential therapeutic values of Korean Red Ginseng extract (KRGE) in autoimmune disorders of nervous system have not been fully investigated. Methods: We used an acute experimental autoimmune encephalomyelitis animal model of multiple sclerosis and determined the effects and mechanism of KRGE on spinal myelination. Results: Pretreatment with KRGE (100 mg/kg, orally) for 10 days before immunization with myelin basic protein $(MBP)_{68-82}$ peptide exerted a protective effect against demyelination in the spinal cord, with inhibited recruitment and activation of immune cells including microglia, decreased mRNA expression of detrimental inflammatory mediators (interleukin-6, interferon-${\gamma}$, and cyclooxygenase-2), but increased mRNA expression of protective inflammatory mediators (insulin-like growth factor ${\beta}1$, transforming growth factor ${\beta}$, and vascular endothelial growth factor-1). These results were associated with significant downregulation of p38 mitogen-activated protein kinase and nuclear factor-${\kappa}B$ signaling pathways in microglia/macrophages, T cells, and astrocytes. Conclusion: Our findings suggest that KRGE alleviates spinal demyelination in acute experimental autoimmune encephalomyelitis through inhibiting the activation of the p38 mitogen-activated protein kinase/nuclear factor-${\kappa}B$ signaling pathway. Therefore, KRGE might be used as a new therapeutic for autoimmune disorders such as multiple sclerosis, although further investigation is needed.

• Journal of Navigation and Port Research
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• v.34 no.3
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• pp.181-187
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• 2010

The performance of underwater wireless communication system is influenced on channel characteristic. Especially, a delay spread cause by reverberation and multi-path happen the ISI (Inter Symbol Interference) and reduces the communication performance. In this paper, we study the application of high speed data transmission in underwater to use the OFDM (Orthogonal Frequency Division Multiplexing) technique for robust the reverberation and multi-path. we confirm the performance of communication in underwater to use the model for actually underwater channel simulation model. As a result, we acquired the BER of modulation techniques. The BER of single carrier is $2{\times}10^{-1}$ and BER of multi carrier is $8{\times}10^{-2}$ in 1000m.

• Journal of Digital Convergence
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• v.18 no.10
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• pp.129-136
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• 2020

The purpose of this study is to identify the influence of external-social and cultural factors on the perception of corruption in the public society through the Structural Equation Model(SEM) and to seek ways to reduce corruption in the public society. Currently the level of corruption in public sectors that people think is still large, and it is necessary to continuously reduce corruption in public sectors in order to improve national competitiveness. Since one society is a part of a country in system theory and social network theory, public society needs quantitative research in order to find the causes of corruption and solve them. The model was built and the variables were defined in SEM based on 600 questionnaires. As a result of analysis, corruption in public offices has decreased since the implementation of the solicitation and graft law, and socio-cultural factors have had a direct impact on corruption in public offices. The further research area is to seek detailed ways for transforming the education and awareness of civil society across the country in addition to the efforts of the public officials themselves in order to reduce corruption in public offices.