• Journal of the Optical Society of Korea
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• v.17 no.2
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• pp.213-218
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• 2013

Although infrared focal plane array (IRFPA) detectors have been commonly used, non-uniformity correction (NUC) remains an important problem in the infrared imaging realm. Non-uniformity severely degrades image quality and affects radiometric accuracy in infrared imaging applications. Residual non-uniformity (RNU) significantly affects the detection range of infrared surveillance and reconnaissance systems. More effort should be exerted to improve IRFPA uniformity. A novel NUC method that considers the surrounding temperature variation compensation is proposed based on the binary nonlinear non-uniformity theory model. The implementing procedure is described in detail. This approach simultaneously corrects response nonlinearity and compensates for the influence of surrounding temperature shift. Both qualitative evaluation and quantitative test comparison are performed among several correction technologies. The experimental result shows that the residual non-uniformity, which is corrected by the proposed method, is steady at approximately 0.02 percentage points within the target temperature range of 283 K to 373 K. Real-time imaging shows that the proposed method improves image quality better than traditional techniques.

• Steel and Composite Structures
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• v.25 no.4
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• pp.485-496
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• 2017

In this paper, damage detection has been introduced as an optimization problem and a two-step method has been proposed that can detect the location and severity of damage in truss structures precisely and reduce the volume of computations considerably. In the first step, using the residual force vector concept, the suspected damaged members are detected which will result in a reduction in the number of variables and hence a decrease in the search space dimensions. In the second step, the precise location and severity of damage in the members are identified using the genetic algorithm and the results of the first step. Considering the reduced search space, the algorithm can find the optimal points (i.e. the solution for the damage detection problem) with less computation cost. In this step, the Efficient Correlation Based Index (ECBI), that considers the structure's first few frequencies in both damaged and healthy states, is used as the objective function and some examples have been provided to check the efficiency of the proposed method; results have shown that the method is innovatively capable of detecting damage in truss structures.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.2
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• pp.103-111
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• 2015

In general, no particularly well-established standards have been in place so far, for the method of evaluating the deteriorated level of pipes and ducts of industrial facilities. For that reason, the evaluation depends upon various studies which are based on the analysis of the residual life, thickness thinning, closure rate, and scale thickness that measure a few specific positions of pipes. It also depends upon the expertise in business operation and the specific techniques conducted by the inspection companies and institutions. This research introduces the concept of measuring units per section and the selection method of measurement points per section. Furthermore, specific methodologies were developed to plan and analyze deterioration level of industrial pipes and ducts by engineers and managers using a section map. Consequently, applying the outcomes from this study to the plant equipment of the incineration facility resulted in saving 42% of the repairing and remodeling cost.

• Journal of the Korean institute of surface engineering
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• v.38 no.3
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• pp.89-94
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• 2005

We investigate the reaction stability of cobalt and nickel with side-wall materials of $SiO_2\;and\;Si_3N_4$. We deposited 15nm-Co and 15nm-Ni on $SiO_2(200nm)/p-type$ Si(100) and $Si_3N_4(70 nm)/p-type$ Si(100). The samples were annealed at the temperatures of $700\~1100^{\circ}C$ for 40 seconds with a rapid thermal annealer. The sheet resistance, shape, and composition of the residual materials were investigated with a 4-points probe, a field emission scanning electron microscopy, and an AES depth profiling, respectively. Samples of annealed above $1000^{\circ}C$ showed the agglomeration of residual metals with maze shape and revealed extremely high sheet resistance. The Auger depth profiling showed that the $SiO_2$ substrates had no residual metallic scums after $H_2SO_4$ cleaning while $Si_3N_4$ substrates showed some metallic residuals. Therefore, the $SiO_2$ spacer may be appropriate than $Si_3N_4$ for newly proposed Co/Ni composite salicide process.

• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3465-3473
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• 2021

For a long time, research into integrated deterministic-probabilistic safety assessment has been continuously conducted to point out and overcome the limitations of classical ET (event tree)/FT (fault tree) based PSA (probabilistic safety assessment). The current paper also attempts to assert the reason why a technical transformation from classical PSA is necessary with a re-interpretation of the categories of risk. In this study, residual risk was classified into interpolating- and extrapolating-censored categories, which represent risks that are difficult to identify through an interpolation or extrapolation of representative scenarios due to potential nonlinearity between hardware and human behaviors intertwined in time and space. The authors hypothesize that such risk can be dealt with only if the classical ETs/FTs are freely relocated, entailing large-scale computation associated with physical models. The functional elements that are favorable to find residual risk were inferred from previous studies. The authors then introduce their under-development enabling techniques, namely DICE (Dynamic Integrated Consequence Evaluation) and DeBATE (Deep learning-Based Accident Trend Estimation). This work can be considered as a preliminary initiative to find the bridging points between deterministic and probabilistic assessments on the pillars of big data technology.

• Earthquakes and Structures
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• v.16 no.5
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• pp.589-599
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• 2019

Conventional buckling restrained braces used in concentrically braced frames are expected to yield in both tension and compression without major degradation of capacity under severe seismic ground motions. One of the weakness points of a standard buckling restrained braced frame is the low post-yield stiffness and thus large residual deformation under moderate to severe ground motions. This phenomenon can be attributed to low post-yield stiffness of core member in a BRB. This paper introduces a multi-core buckling restrained brace. The multi-core term arises from the use of more than one core component with different steel materials, including high-performance steel (HPS-70W) and stainless steel (304L) with high strain hardening properties. Nonlinear dynamic time history analyses were conducted on variety of diagonally braced frames with different heights, in order to compare the seismic performance of regular and multi-core buckling restrained braced frames. The results exhibited that the proposed multi-core buckling restrained braces reduce inter-story and especially residual drift demands in BRBFs. In addition, the results of seismic fragility analysis designated that the probability of exceedance of residual drifts in multi-core buckling restrained braced frames is significantly lower in comparison to standard BRBFs.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.3
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• pp.199-206
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• 1981

This paper presents a method of calculation of the stresses, the strains and the deflections due to welding in L shape and in T shape. Using step by step method of plasticity and establishing the equilibrium conditions in section, we calculated thermal stresses and strains during welding and in the final step of calculation we got the residual stresses, strains and the deflections due to welding. Also we measured the stresses and the strains with hole-drilling method and compared the results with the method of calculation presented in this paper. Because of its symmetry of section, the deflection due to welding in T shape is generally much less than that in L shape. The residual stresses are tensile in welded joints and HAZ, and compressive in base metal as butt welding of plates, but the compressive stresses in base metal decrease repidly as the points are away from welded joint except horizontal plates of T shape. The theoretical method of calculaiton presented in this paper coincides faily well with the experiment.

• Communications for Statistical Applications and Methods
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• v.10 no.3
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• pp.859-871
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• 2003

In this paper we introduce some adaptive M-estimators using selector statistics to estimate the slope of regression model under the symmetric and continuous underlying error distributions. This selector statistics is based on the residuals after the preliminary fit L$_1$ (least absolute estimator) and the idea of Hogg(1983) and Hogg et. al. (1988) who used averages of some order statistics to discriminate underlying symmetric distributions in the location model. If we use L$_1$ as a preliminary fit to get residuals, we find the asymptotic distribution of sample quantiles of residual are slightly different from that of sample quantiles in the location model. If we use the functions of sample quantiles of residuals as selector statistics, we find the suitable quantile points of residual based on maximizing the asymptotic distance index to discriminate distributions under consideration. In Monte Carlo study, this adaptive M-estimation method using selector statistics works pretty good in wide range of underlying error distributions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.2
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• pp.382-390
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• 1995

Failure of connecting rod in automotive engine may cause catastrophic situation. The corner radius at small end has an effect on stress raising. To investigate the stress distribution in connecting rod during operation, the finite element analysis was used by giving possible maximum tension and compression. Excessive sizing after forging connecting rod may result in the tensile residual stress which lower the fatigue life and cause premature failures. It was shown that when the sizing amount is too large, the location of high tensile residual stress coincide with that of high stress amplitude during operation through the elastic-plastic finite element analysis. The endurance limit moves down due to the surface finish and decarburization, which combines with the movement of resultant stress points to dangerous range. It was concluded that the precise control of sizing and enough corner radius are necessary to a reliability of connecting rod.

• Structural Engineering and Mechanics
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• v.29 no.6
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• pp.709-729
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• 2008

This paper describes a three-dimensional dynamic finite element analysis of two/multiple shots impacting on a metallic component. The model is validated against a published numerical study. An extensive parametric study is conducted to investigate the effect of shot impacting with overlap on the resulting residual stress profile within the component, including time interval between shot impacts, separation distance between the impacting points, and impacting velocity of successive shots. Several meaningful conclusions can be drawn regarding the effect of shot impacting with overlap.