• Journal of the Korea Convergence Society
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• v.9 no.7
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• pp.223-230
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• 2018

In the case of a one-shot logistic equipment system that has been stored for a long time, reliability changes with the passage of time. Therefore, when the time comes to use, the storage reliability of the product is an important quality characteristic, and the existing studies have focused on the research for calculating the optimal period inspection cycle to improve the storage reliability. In this study, we analyzed the influence of the two factors on the storage reliability at the convergence point by analyzing the design reliability as well as the periodic inspection cycle. To do this, we applied the existing Martinez storage reliability model to the missile, a representative product of a one-shot system, and analyzed the quantitative effects of the design reliability and the periodic inspection cycle. From the results of the analysis, it was confirmed that the maintenance of the periodic inspection cycle is more important for the improvement of the storage reliability than the design reliability in the design reliability category of the current product.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.9
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• pp.930-937
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• 2014

Inverse synthetic aperture radar (ISAR) images can be generated by radar which radiates the electromagnetic wave to a target and receives signal reflected from the target. ISAR images can be widely used to target detection and recognition. This paper proposed a method of generation of high resolution ISAR images by synthesizing frequency spectrums of each stepped chirp waveform in one burst and sub-sampling in frequency domain. This process is performed over entire bursts during coherent processing interval. Conventional ISAR image generation method using stepped frequency waveform has a severe problem of short unambiguous range, loading to ghost phenomenon. However, this problem can be resolved by the proposed method. In simulations, we generate high resolution ISAR image of the moving target which is Boeing-737 aircraft model composed of several ideal point scatterers.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1241-1248
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• 2012

The objective of this study is to evaluate the thermal damage characterization of a silicon wafer subjected to a CW laser beam. The variation in temperature and stress during laser beam irradiation has been predicted using a three-dimensional numerical model. The simulation results indicate that the specimen might crack when a 93-$W/cm^2$ laser beam is irradiated on the silicon wafer, and surface melting can occur when a 186-$W/cm^2$ laser beam is irradiated on the silicon wafer. In experiments, straight cracks in the [110] direction were observed for a laser irradiance exceeding 102 $W/cm^2$. Furthermore, surface melting was observed for a laser irradiance exceeding 140 $W/cm^2$. The irradiance for surface melting is less than that in the simulation results because multiple reflections and absorption of the laser beam might occur on the surface cracks, increasing the absorbance of the laser beam.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.1
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• pp.20-27
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• 2016

The prediction of combustion instability is important to avoid an obvious threat to the structural safety and the motor performance because it affects the apparent response function of the propellant, the burning rate, and a mean flow Mach number at the local surface. The combustion instability occurs in case acoustic waves were coupled with the combustion/flow dynamic frequency. In this paper, an acoustic instability model is derived from the nonlinear wave equation for analysing acoustic dynamics in solid rocket motors. The chamber pressure and burning rate effects on combustion instability have been investigated.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.1
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• pp.31-37
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• 2017

In this paper, computation results of reducible modeling, stress recovery and energy release rate were compared with the results of VABS, Virtual Crack Closure Technique. The result of stress recovery analysis for 1-D model including the stiffness matrix is compared with stress results of three-dimensional 3-D FEM. Energy release rate of composite beam with longitudinal cracks is calculated and compare verifications of numerical analysis results of 3-D FEM and VABS. The procedure of calculating energy release rate through dimensional reduction and stress recovery is intended to be efficient and be utilized in the life-cycle of high-altitude uav's wing, wind blades and tilt rotor blade.

• Journal of Industrial Convergence
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• v.17 no.4
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• pp.59-67
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• 2019

This study examined the effects of corporate social responsibilities on company-consumer identification, Loyalty, purchase intention and trust. Questionnaires were distributed to 300 members of corporations. Of the returned questionnaires, 233 questionnaires were used for empirical study. Analysis of linear structural equation was used to test the model and the hypotheses. The overall adequacy was found to be allowable. Several important findings emerged from this research. First, corporate social responsibilities was related with company-consumer identification. Second, company-consumer identification had positive influences on purchase intention and trust. Third, trust was related with purchase intention. This study provides guidelines to help managers better understanding how to increase company-consumer identification, purchase intention and consumer's trust and make better decisions about procedures, outcomes and interactions for their consumers.

• Journal of Digital Convergence
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• v.13 no.4
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• pp.205-210
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• 2015

The auto industry has significantly evolved to the extent that much attention is paid to M2M (Machine-to-Machine) communication. In M2M communication which was first used in meteorology, environment, logistics, national defense, agriculture and stockbreeding, devices automatically communicate and operate in accordance with varying situations. M2M system is applied to vehicles, specifically to device-to-device communication inside cars, vehicle-to-vehicle communication, communication between vehicles and traffic facilities and that between vehicles and surroundings. However, communication systems are characterized by potential intruders' attacks in transmission sections, which may cause serious safety problems if vehicles' operating system, control system and engine control parts are attacked. Thus, device-to-device secure communication has been actively researched. With a view to secure communication between vehicular devices, the present study drew on hash functions and complex mathematical formulae to design a protocol, which was then tested with Casper/FDR, a tool for formal verification of protocols. In brief, the proposed protocol proved to operate safely against a range of attacks and be effective in practical application.

• Journal of Internet Computing and Services
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• v.13 no.5
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• pp.21-31
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• 2012

Threat Evaluation(TE) which has air intelligence attained by identifying friend or foe evaluates the target's threat degree, so it provides information to Weapon Assignment(WA) step. Most of TE data are passed by sensor measured values, but existing techniques(fuzzy, bayesian network, and so on) have many weaknesses that erroneous linkages and missing data may fall into confusion in decision making. Therefore we need to efficient Threat Evaluation system that can refine various sensor data's linkages and calculate reliable threat values under unpredictable war situations. In this paper, we suggest new threat evaluation system based on information fusion JDL model, and it is principle that combine fuzzy which is favorable to refine ambiguous relationships with bayesian network useful to inference battled situation having insufficient evidence and to use learning algorithm. Finally, the system's performance by getting threat evaluation on an air defense scenario is presented.

• Journal of the korean society of oceanography
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• v.37 no.1
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• pp.1-9
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• 2002

Cable voltage was measured simultaneously at Hamada, Japan and Pusan, Korea, using an inservice telephone cable from March to December 1990. The spectral and harmonic analyses of these data sets show that tidal signals are dominant, and that tidal constituents $M_2$ and $O_1$, which are not affected by solar geomagnetic variations, have almost the same amplitude and are of opposite phase to each other. comparing the voltage difference in 1990 with that measured using the now abandoned cable in 1998, there are dominant tidal signals at the same periods in both data sets. They have approximately the same amplitude and phase for $M_2andO_1$. The relationship between the observed voltage and the volume transport through the Korea Strait can be considered robust and stable over time. The conversion factor from voltage to transport is estimated to be $11.9{\times}10^6m^3S^{-1}volt^{-1}$ by comparing the amplitude of model-derived $M_2$ tidal transport with that of the voltage difference in 1998. This value changes to $8.6{\times}10^6m^3S^{-1}volt^{-1}$ when taking into consideration the horizontal electric current effect. This effect depends on the downstream length scale of the flow. To obtain a more reliable and stable conversion factor from voltage to transport, the voltage should be compared with observed sub-tidal transports, which may have long downstream length scales.

• Genomics & Informatics
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• v.8 no.1
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• pp.50-57
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• 2010

Mercuric chloride, a model nephrotoxicant was used to elucidate time- and dose- dependent global gene expression changes associated with proximal tubular toxicity. Rat kidney cell lines NRK-52E cells were exposed for 2, 6 and 12 hours and with 3 different doses of mercuric chloride. Cell viability assay showed that mercuric chloride had toxic effects on NRK-52E cells causing 20% cell death (IC20) at $40{\mu}M$ concentration. We set this IC20 as high dose concentration and 1/5 and 1/25 concentration of LC20 were used as mid and low concentration, respectively. Analyses of microarray data revealed that 738 genes were differentially expressed (more than two-fold change and p<0.05) by low concentration of mercuric chloride at least one time point in NRK-52E cells. 317 and 2,499 genes were differentially expressed at mid and high concentration of mercuric chloride, respectively. These deregulated genes showed a primary involvement with protein trafficking (CAV2, CANX, CORO1B), detoxification (GSTs) and immunity and defense (HMOX1, NQO1). Several of these genes were previously reported to be up-regulated in proximal tubule cells treated with nephrotoxicants and might be aid in promoting the predictive biomarkers for nephrotoxicity.