• Journal of Sensor Science and Technology
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• v.22 no.4
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• pp.262-267
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• 2013

We developed a real-time screening system using optical coherence tomography (OCT) to distinguish the fruitful melon seeds efficiently. Cross-section images of melon seeds infected with Cucumber green mottle mosaic virus (CGMMV) showed an additional layer that did not appear in normal seeds. Additional layer appeared under $100{\sim}300{\mu}m$ from the surface of the seed. OCT can visualize the micro-structural and morphological changes of the internal seed structure. Real-time OCT seed screening system provided the real-time, non-destructive, cross-section image and quantitative information such as A-scan analysis of selected region in the cross-section image. We can distinguish the viral infection seeds while monitoring the averaged A-scan analysis graph in real-time by considering the second peak value of the graph which refers to the layer that occurred owing to the virus. Real-time OCT seed screening system could assist to distinguish the disease caused by CGMMV.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.6
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• pp.550-557
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• 2008

Delamination damage at a bolt hole in a composite stiffened panel was detected using a built-in piezoelectric active sensor array. Various signal processing techniques were used to detect an invisible small scale delamination around a fastener hole due to localized transverse loading. A built-in piezoelectric sensor array was used to generate diagnostic signals and to measure response signals. Then, the response signals were processed to extract damage-sensitive features. Damage indexes were calculated to estimate the severity and location of the damage from the features.

• Journal of Welding and Joining
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• v.31 no.6
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• pp.32-36
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• 2013

The large-scale structures have the possibility that there are defects such as cracks due to stress concentration caused by geometric discontinuities in the structure. In this respect, the assessment of fatigue life and the development of structural health monitoring(SHM) are very important. Fatigue design of structure is typically accomplished either using a set of stress cycle (S-N) data obtained from fatigue tests or using the fracture mechanics approach. The stress intensity factor(SIF) is required for the estimation of fatigue crack propagation life from the linear elastic fracture mechanics (LEFM) perspective. In this study, Macro Fiber Composie(MFC) sensor for the measurement of SIF of two dimensional cracks is used. The SIF based on the piezoelectric constitutive law and fracture mechanics are calculated. The measured values of the SIF are later used for the prediction of the crack propagation life. In this study, the measured value of the SIF and the fatigue life are compared with the theoretical results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.267-270
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• 2005

Finite element model of pressurized water reactor internals were obtained using ANSYS software package to analyze dynamic characteristics. The pressure vessel, hold-down ring, alinement key, core support barrel(CSB), upper guide structure(UGS) and fluid gap were fully modeled using structural solid element(SOLID45) and fluid element(FLUID80) which is one of element types. Also modal analysis using the above finite element model has been performed. As a result, it was found that the fundamental beam mode natural frequency of the CSB were 8.2 Hz, the shell mode one 14.5 Hz. To verify the Finite Element Analysis(FEA), we compare the analysis result with experimental data that is obtained from the plant IVMS(internal Vibration Monitoring System). The experimental results are good agreement with the FEA model.

• Journal of Information Technology Services
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• v.14 no.4
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• pp.81-104
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• 2015

Intentional information systems (IS) misuse is a serious problem in many organizations. This study aims at developing the theoretical framework of deterring IS misuse on the basis of Nagin's General Deterrence Theory (GDT) which is very famous in the area of socio-criminology. Applying GDT to the IS misuse situation could be reasoned that the perceived certainty and the perceived severity of sanctions associated with committing IS misuse have positive impact on deterring the deviant behaviors. Also, these two constructs (certainty of sanctions and severity of sanctions) could be inferred to be influenced by the four types of IS security countermeasures (security policies, security awareness program, monitoring practices and preventive security software) derived through critically reviewing IS security-relevant literature. The proposed research model and ten hypotheses were empirically analysed using structural equation modelling with the data collected by conducting a questionnaire survey of staff members in business organizations in Korea. As a result, it was found that five ones of ten hypotheses were supported. It is thought that this study makes theoretical contribution to expanding research area of IS security and also has strong implications for IS security management practices within organizations.

• The Journal of Asian Finance, Economics and Business
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• v.6 no.1
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• pp.249-259
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• 2019

Studies looking at many aspects of SNS addiction have dramatically increased in recent years. Most of the SNS addiction research has focused on individual behaviors. There is little academic research about SNS addiction in the workplace. This study, therefore, plans to examine the organizational behaviors related to SNS addiction in the workplace. We investigate whether negative behaviors in the workplace induce SNS addiction, and how SNS addiction influences the organizational or social attitudes of employees. We also explore the possible mediating effect of SNS addiction. We use an online survey and collected 285 responses from office workers in South Korea. The results tested by a structural equation modeling indicate, first, that both abusive supervision and workplace bullying have aroused SNS addiction among employees; second, employees' SNS addiction increases both from work-to-family-conflicts and family-to-work-conflicts; and third, SNS addiction fully mediates the relationship between abusive supervision and workplace bullying, as well as the relationship among abusive supervision, workplace bullying, and work-family conflicts. The study finds that abusive supervision and workplace bullying are important antecedents of SNS addiction, and that SNS addiction affects conflicts in both work-to-family and family-to-work situations. Therefore, companies should be cognizant of potential mediating influences in monitoring employees' SNS usage in order to improve their work environments.

• Bulletin of the Korean Chemical Society
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• v.18 no.6
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• pp.588-594
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• 1997

Gelation time, gel structure and volatility of by-products during gelation of PZT sol-gel processing were investigated by FT-IR spectroscopy. FT-IR spectroscopic study was performed on PZT gels with the various H₂O contents (1, 2 and 3 mol) and the several types (HNO₃, NH₄OH) and amounts (0.1, 0.2 mol) of catalysts, monitoring temporal (0, 1, 3, 10 weeks, 3 months and 3 years) and thermal (100-700 ℃) changes of FT-IR spectra. The interpretation of temporal change of the spectra revealed two trends. One is under the condition of 1 mol H₂O, 1 mol H₂O+0.1 mol HNO₃, 3 mol H₂O and the other is for 1 mol H₂O+0.1 mol NH₄OH, 2 mol H₂O, 1 mol H₂O+0.2 mol HNO₃. The gel structures and the gelation times for these conditions were discussed in comparison with the reported results of SiO₂, and we suggested the reaction mechanisms for these structural characteristics. Thermal variation of FT-IR spectra was interpreted as the evolution processes of gel by investigating the evaporation of solvent and the decomposition of organic residues.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.31-35
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• 2008

This test cell is developed to provide the fundamentals of operational mechanism and structural configuration, and further to verify thermodynamic calculation with this test data to the institutes or laboratories research and study gas turbine engine for academic purpose. The test cell is installed to monitor and collect real-time data as to temperature, pressure, thrust, fuel flow, and air flow etc. using by NI DAQ(Data acquisition)device and LabVIEW program based on 30lbf-micro turbojet engine.

• Structural Monitoring and Maintenance
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• v.2 no.3
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• pp.181-197
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• 2015

Assessing the condition of paint on civil structures is an important but challenging and costly task, in particular when it comes to large and complex structures. Current practices of visual inspection are labour-intensive and time-consuming to perform. In addition, this task usually relies on the experience and subjective judgment of individual inspectors. In this study, hyperspectral imaging and classification techniques are proposed as a method to objectively assess the state of the paint on a civil or other structure. The ultimate objective of the work is to develop a technology that can provide precise and automatic grading of paint condition and assessment of degradation due to age or environmental factors. Towards this goal, we acquired hyperspectral images of steel surfaces located at long (mid-range) and short distances on the Sydney Harbour Bridge with an Acousto-Optics Tunable filter (AOTF) hyperspectral camera (consisting of 21 bands in the visible spectrum). We trained a multi-class Support Vector Machines (SVM) classifier to automatically assess the grading of the paint from hyperspectral signatures. Our results demonstrate that the classifier generates highly accurate assessment of the paint condition in comparison to the judgement of human experts.

• Structural Monitoring and Maintenance
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• v.2 no.3
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• pp.213-236
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• 2015

The paper presents an investigation into the mode conversion and scattering characteristics of guided waves at delaminations in laminated composite beams. A three-dimensional (3D) finite element (FE) model, which is experimentally verified using data measured by 3D scanning laser vibrometer, is used in the investigation. The study consists of two parts. The first part investigates the excitability of the fundamental anti-symmetric mode ($A_0$) of guided wave in laminated composite beams. It is found that there are some unique phenomena, which do not exist for guided waves in plate structures, make the analysis become more complicated. The phenomena are observed in numerical study using 3D FE simulations. In the second part, several delaminated composite beams are studied numerically to investigate the mode conversion and scattering characteristics of the $A_0$ guided wave at delaminations. Different sizes, locations and through-thickness locations of the delaminations are investigated in detail. The mode conversion and scattering phenomena of guided waves at the delaminations are studied by calculating reflection and transmission coefficients. The results show that the sizes, locations and through-thickness locations of the delaminations have significant effects on the scattering characteristics of guided waves at the delaminations. The results of this research would provide better understanding of guided waves propagation and scattering at the delaminations in the laminated composite beams, and improve the performance of guided wave damage detection methods.