• Computers and Concrete
• /
• v.21 no.6
• /
• pp.649-659
• /
• 2018

Adaptive neuro-fuzzy inference systems (ANFIS) can be efficient in modelling non-linear, complex and ambiguous behavior of cement-based materials undergoing combined damage factors of different forms (physical and chemical). The current work investigates the use of ANFIS to model the behavior (time of failure (TF)) of a wide range of concrete mixtures made with different types of cement (ordinary and portland limestone cement (PLC)) without or with supplementary cementitious materials (SCMs: fly ash and nanosilica) under various exposure regimes with the most widely used chloride-based de-icing salts (individual and combined). The results show that predictions of the ANFIS model were rational and accurate, with marginal errors not exceeding 3%. In addition, sensitivity analyses of physical penetrability (magnitude of intruding chloride) of concrete, amount of aluminate and interground limestone in cement and content of portlandite in the binder showed that the predictive trends of the model had good agreement with experimental results. Thus, this model may be reliably used to project the deterioration of customized concrete mixtures exposed to such aggressive conditions.

• Analytical Science and Technology
• /
• v.35 no.1
• /
• pp.1-7
• /
• 2022

This study suggests a new one-step fluorescent cyanoacylate-fuming method for developing fingerprints by using a CAB mixed with dimethylaminobenzalde (DMAB) and cyanoacylate (CA) in a specific ratio. CAB is prepared by mixing 2.5 % (w/w) DMAB with CA and fumigated at 180 ℃. Under these conditions, developing fingerprints showed the best results. The fuming method using CAB develops latent fingerprints into fluorescence and has a higher sensitivity than CA, and it showed comparable or better contrast to existing fluorescence enhancement methods. It was also applicable on a variety of non-porous surfaces that can be encountered at ordinary times. This method is more useful than conventional fluorescent dyeing methods in that it minimizes damage to fingerprints or samples, makes it easy to manufacture, saves time, and can use existing current equipment as it is.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.31 no.3
• /
• pp.158-169
• /
• 2019

A probabilistic model that can predict the residual useful lifetime of structure is formulated by using the gamma process which is one of the stochastic processes. The formulated stochastic model can take into account both the sampling uncertainty associated with damages measured up to now and the temporal uncertainty of cumulative damage over time. A method estimating several parameters of stochastic model is additionally proposed by introducing of the least square method and the method of moments, so that the age of a structure, the operational environment, and the evolution of damage with time can be considered. Some features related to the residual useful lifetime are firstly investigated into through the sensitivity analysis on parameters under a simple setting of single damage data measured at the current age. The stochastic model are then applied to the rubble-mound breakwater straightforwardly. The parameters of gamma process can be estimated for several experimental data on the damage processes of armor rocks of rubble-mound breakwater. The expected damage levels over time, which are numerically simulated with the estimated parameters, are in very good agreement with those from the flume testing. It has been found from various numerical calculations that the probabilities exceeding the failure limit are converged to the constraint that the model must be satisfied after lasting for a long time from now. Meanwhile, the expected residual useful lifetimes evaluated from the failure probabilities are seen to be different with respect to the behavior of damage history. As the coefficient of variation of cumulative damage is becoming large, in particular, it has been shown that the expected residual useful lifetimes have significant discrepancies from those of the deterministic regression model. This is mainly due to the effect of sampling and temporal uncertainties associated with damage, by which the first time to failure tends to be widely distributed. Therefore, the stochastic model presented in this paper for predicting the residual useful lifetime of structure can properly implement the probabilistic assessment on current damage state of structure as well as take account of the temporal uncertainty of future cumulative damage.

• Journal of Environmental Impact Assessment
• /
• v.24 no.2
• /
• pp.190-203
• /
• 2015

VRI(Vulnerability-Resilience Index), which is defined as a function of 3 variables: climate exposure, sensitivity, and adaptive capacity, has been quantified for the case of Typhoon which is one of the extreme weathers that will become more serious as climate change proceeds. Because VRI is only indicating the relative importance of vulnerability between regions, the VRI quantification is prerequisite for the effective adaptation policy for climate in Korea. For this purpose, damage statistics such as amount of damage, occurrence frequency, and major damaged districts caused by Typhoon over the past 20 years, has been employed. According to the VRI definition, we first calculated VRI over every district in the case of both with and without weighting factors of climate exposure proxy variables. For the quantitative estimation of weighting factors, we calculated correlation coefficients (R) for each of the proxy variables against damage statistics of Typhoon, and then used R as weighting factors of proxy variables. The results without applying weighting factors indicates some biases between VRI and damage statistics in some regions, but most of biases has been improved by applying weighting factors. Finally, due to the relations between VRI and damage statistics, we are able to quantify VRI expressed as a unit of KRW, showing that VRI=1 is approximately corresponding to 500 hundred million KRW. This methodology of VRI quantification employed in this study, can be also practically applied to the number of future climate scenario studies over Korea.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2001.05a
• /
• pp.1-4
• /
• 2001

A new non-destructive fatigue prediction model of the composite laminates is developed. The natural frequencies of fatigue-damaged laminates under extensional loading are related to the fatigue lift of the laminates by establishing the equivalent flexural stiffness reduction as a function of the elastic properties of sublaminates. The flexural stiffness is derived by relating the $90^{\circ}$-ply elastic modulus reduction, and using the laminate plate theory to the degraded elastic modulus and the intact elastic modulus of other laminate. The natural frequency reduction model, in which the dominant fatigue mode can be identified from the sensitivity scale factors of sublaminate elastic properties, provides natural frequency vs. fatigue cycle curves for the composite laminates. Vibration tests were also conducted on $[\textrm{90}_{2}\textrm{0}_{2}]_s$ carbon/epoxy laminates to verify the natural frequency reduction model. Correlations between the predictions of the model and experimental results are good.

• Journal of Mechanical Science and Technology
• /
• v.18 no.2
• /
• pp.230-239
• /
• 2004

A compact model approach of a network of spring elements for elastic loading is presented for the thermal deformation analysis of BGA package assembly. High-sensitivity moire interferometry is applied to evaluate and calibrated the model quantitatively. Two ball grid array (BGA) package assemblies are employed for moire experiments. For a package assembly with a small global bending, the spring model can predict the boundary conditions of the critical solder ball excellently well. For a package assembly with a large global bending, however, the relative displacements determined by spring model agree well with that by experiment after accounting for the rigid-body rotation. The shear strain results of the FEM with the input from the calibrated compact spring model agree reasonably well with the experimental data. The results imply that the combined approach of the compact spring model and the local FE analysis is an effective way to predict strains and stresses and to determine solder damage of the critical solder ball.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.290-290
• /
• 2022

Powdery mildew is known to be one of the serious diseases in C. moschata cultivation. Plants infected with powdery mildew cause damage to cultivation areas such as occurrence of deformity fruit and decrease in quantity. also, it has been reported that many farms have difficulties in controlling powdery mildew due to the outbreak under various conditions throughout the year. Therefore, this study intends to perform a phenotype test and a genotype test for C. moschata 60 lines grown in Jenong S&T. Podospareaxanthii, known as a pathogen that causes powder mildew disease in pumpkins in Korea, was collected and used as an inoculation source, phenotype test was performed by examining the infection area rate(%) of powdery mildew disease that occurred in leaves 25 days after inoculation. It was determined that 0% of the infection area rate was in the first stage, 1 to 5% in the second stage, 6 to 15% in the third stage, 16 to 30% in the fourth stage, and 31% or more in the fifth stage, The first and second stages were judged as resistance, the third as moderate resistance, and the fourth and fifth stages as sensitivity. As a result of the phenotype test, it was confirmed that the resistance was 21 points, moderate resistance was 14 points, and sensitivity was 25 points. After searching for the genes related to powdery mildew resistance resistance, pm-0, CmbHLH87, and LOC111453072, 21 points of resistance and 9 points of moderate resistance identified through phenotype tests were identified through gel electrophoresis after polymerase chain reaction(PCR) using 5 primers related to 3 genes. As a result of genotype testing of a total 30 points, the CmbHLH87 and LOC111453072 gene were found to be resistant bands in all points, PMR1 was identified as 20 points for resistance, 4 points for moderate resistance, and 6 points for sensitivity, PMR2 was not identified in the entire band, and PMR5 was identified as 18 point for resistance, 3 points for moderate resistance, and 9 points for sensitivity. As a result, when comparing the phenotype test results and genotype test results, CmbHLH87 and LOC111453072 genes was 100% consistent in resistance and moderate resistance, PMR1 was 95.2% in resistance, 44.4% in moderate resistance, and PMR5 was 90% in resistance and 33.3% in moderate resistance, PMR2 was not consistent in resistance and moderate resistance. Therefore, it is expected that more accurate PMR test will be possible by using molecular markers(PMR1, PMR5) and by developing CmbHLH87 and LOC111453072 gene-related molecular markers.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.6
• /
• pp.2293-2302
• /
• 2013

Flood inundation map has been used as a fundamental information in flood risk management. However, there are various sources of uncertainty in flood inundation mapping, which can be another risk in preventing damage from flood. Therefore, it is necessary to remove or reduce uncertainty sources to improve the accuracy of flood inundation maps. However, the entire removal of uncertainty source may be impossible and inefficient due to limitations of knowledge and finance. Sensitivity analysis of uncertainty sources allows an efficient flood risk management by considering various conditions in flood inundation mapping because an uncertainty source under different conditions may propagate in different ways. The objectives of this study are (1) to perform sensitivity analysis of uncertainty sources by different conditions on flood inundation map using the FOA method and (2) to find a major contributor to a propagated uncertainty in the flood inundation map in Flatrock at Columbus, U.S.A. Result of this study illustrates that an uncertainty in a variable is differently propagated to flood inundation map by combination with other uncertainty sources. Moreover, elevation error was found to be the most sensitive to uncertainty in the flood inundation map of the study reach.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.05a
• /
• pp.311-314
• /
• 2007

The experimental method of measuring dynamic properties of structures was presented. The method is based on the flexural wave propagation characteristics. Using the method, change in structural dynamic properties due to damage is measured. The crack has much more significant impact on the strain energy than the inertial effects. From this, the sensitivity of the dynamic stiffness on the crack location is estimated by calculating the strain energy. When the wave propagates, the strain and kinetic energies shows cyclic changed over space. The crack that occurred at locations where the wave energy is in the form of the potential energy affected most significantly the wave propagation characteristics. The effects of crack location on the wave propagation were used to determine the crack location.

• Journal of Institute of Control, Robotics and Systems
• /
• v.15 no.8
• /
• pp.831-838
• /
• 2009

This paper proposes an IR (infrared) LED (Light Emitting Diode)-based tactile fingertip sensor that can independently measure the normal and tangential force between the hand and an object. The proposed IR LED-based tactile sensor has several advantages over other technologies, including a low price, small size, and good sensitivity. The design of the first prototype is described and some experiments are conducted to show output characteristics of the proposed sensor. Furthemore, the effectiveness of the proposed sensor is demonstrated through anti-slip control in a multifunction myoelectric hand, called the KNU Hand, which includes several novel mechanisms for improved grasping capabilities. The experimental results show that slippage was avoided by simple force control using feedback on the normal and tangential force from the proposed sensor. Thus, grasping force control was achieved without any slippage or damage to the object.