• International Journal of Highway Engineering
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• v.19 no.6
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• pp.97-103
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• 2017

PURPOSES : In this study, the pavement condition of non-mill-and-overlay and mill-and-overlay on deteriorated concrete pavement was compared. In addition, the suitable time to perform the initial overlay was investigated. METHODS : The condition of the pavement sections that were not additionally overlaid on non-mill-and-overlay or mill-and-overlay on deteriorated concrete pavements was investigated according to overlay pavement age. The condition of non-mill-and-overlay and mill-and-overlay sections of expressway route 25, which has more information on overlay history than other routes, was compared according to the number of times of overlay. The relation between the concrete pavement condition just before the overlay and the number of times of overlay was investigated for the non-mill-and-overlay and mill-and-overlay sections for which the first overlay was performed in the same year. RESULTS : The pavement condition of the non-mill-and-overlay sections was better than that of the mill-and-overlay sections, showing higher Highway Pavement Condition Index(HPCI) regardless of overlay pavement age. The number of reflection crackings of the non-mill-and-overlay sections was smaller than that of the mill-and-overlay sections. As a result of observing the cores obtained from the overlay sections, the proportion of the deteriorated non-mill-and-overlay sections was smaller than that of the mill-and-overlay sections. The SD measured just before the overlay on the concrete pavement for which additional overlay was not performed was smaller than that for which additional overlay was performed regardless of the milling of the concrete slab surface. The HPCI of the concrete pavement for which overlay was performed just once was higher than that for which overlay was performed more than one time. CONCLUSIONS : Accordingly, it was concluded that the condition of the non-mill-and-overlay sections was better than that of the mill-and-overlay sections. In addition, the better the condition of concrete pavement just before the initial overlay, the longer the duration of the overlay effect.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.88-93
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• 2008

Weld overlay is one of the residual stress mitigation method which arrest crack. An overlay weld sued in this manner is termed a preemptive weld overlay(PWOL). PWOL was good for distribution of residual stress of dissimilar metal weld(DMW) by previous research. Because range of overlay welding is wide relatively, residual stress distribution on PWR is affected by welding sequence. In order to examine the effect of welding sequence, PWOL was applied to a specific DMW of KORI nuclear power plant by finite element analysis method. As a result, the welding direction that from nozzle to pipe is better good for residual stress distribution on PWR.

• Proceedings of the KAIS Fall Conference
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• 2002.05a
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• pp.106-108
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• 2002

반도체 physical layout design rule이 작아짐에 따라 Proximity effect와 overlay가 Pattern 구현에 크게 영향을 미치고 있다. Metal layer와 contact의 부족한 overlay margin으로 overlay 불량이 발생하고, 감소한 space margin으로 인해 bridge와 같은 문제가 나타난다. 따라서, resolution을 향상시키고, 최소한의 overlay margin을 확보함으로써 미세 pattern의 구현을 가능하게 한다. 이를 위해 OPC와 attPSM 같은 분해능향상기술이 사용된다. 그러나 attPSM의 사용은 원하지 않는 pattern이 생성되는 sidelobe와 같은 문제가 발생한다. 따라서 serial image simulation올 통해 추출한 rule을 rule-based correction에 적용하여 sidelobe현상을 방지한다. 그리고 overlay margin 부족으로 나타나는 문제는 metal layer와 contact overlap되는 영역의 line edge를 확장하고, rule checking을 통해 최소한의 space margin을 확보하여 해결한다 따라서 overlay error를 rule-based correction을 사용하여 효과적으로 방지한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.10
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• pp.873-881
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• 2008

Weld overlay is one of the residual stress mitigation methods which arrest crack initiation and crack growth. Therefore weld overlay can be applied to the region where cracking is likely to be. An overlay weld used in this manner is termed a preemptive weld overlay(PWOL). In pressurized water reactor(PWR) dissimilar metal weld is susceptible region for primary water stress corrosion cracking(PWSCC). In order to examine the effect of PWOL on residual stress mitigation, PWOL was applied to a specific dissimilar metal weld of Kori nuclear power plant by finite element analysis method. As a result, strong compressive residual stress was made in PWSCC susceptible region and PWOL was proved effective preemptive repair method for weldment.

• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.332-343
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• 2016

With the advance of digital technology, new methods which acquire color information and combine it with various contents are emerging. Color has some effect on emotion while it gives some information as component of an image. In addition, change in emotion and sensation from color stimulus makes some change in cognition. This research investigate the effect of color overlay on cognition depending on emotional state. With this goal, subjects consisting of 10 men and 10 women solved some problems with color overlay of red, orange, and green after watching short video clips which intend to induce target emotion. Experimental results show that red color overlay under positive emotion significantly reduces the average score of solving problems, while green overlay under negative emotion significantly increases it. It is also analyzed that there is not statistically significant difference in cognitive function with color overlay while it is significantly better under positive emotion than negative emotion without color overlay.

• Structural Engineering and Mechanics
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• v.52 no.4
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• pp.829-841
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• 2014

The main purpose of this study is to determine the effect of overlay on the crack propagation. In order to simplify the problem, a cement concrete pavement is modeled as an elastic plate on Winkler foundation. To derive the singular integral equations, the Fourier transform and dislocation density function are used. Lobatto-Chebyshev integration formula, as a numerical method, is used to solve the singular integral equations. The numerical solution of stress intensity factor at the crack tip is derived. In order to examine the effect of overlay for resisting crack propagation, numerical analyses are carried out for a cement concrete pavement with an embedded crack and a concrete pavement with an asphalt overlay. Results show the significant factors that influence the crack propagation.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.260-262
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• 2007

In nuclear power plants, residual stress of dissimilar metal weld propagates cracks in the weld metal which is susceptible to stress corrosion cracking. Overlay welding is a process widely used to mitigate residual stress replacing inside tensile stress by compressing stress. The purpose of this paper is to predict the effect of weld overlay by finite element analysis.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.211-216
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• 2002

To investigate transition region in welded overlay relating to disbonding crack, the effect of vanadium addition on disbonding of Cr-Mo steels overlay welded with austenitic stainless steel was studied. V modified Cr-Mo steels have a higher resistance to disbonding than V free Cr-Mo steel. One reason is due to the fact that fine vanadium carbide precipated in base metal traps hydrogen and thus decreases the susceptibility to the disbonding. The second is related to the higher stability of the vanadium and stable carbides formed during PWHT, in which the carbon diffusion to the interface is lower than for V free Cr-Mo steel. Decreasing the carbon content at the interface of the weld overlay shows good resistance to the disbonding. Hence, it is important to control the carbon content at the interface of the weld overlay.

• International Journal of Highway Engineering
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• v.16 no.2
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• pp.91-98
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• 2014

PURPOSES : The objective of this study is to investigate the effect of asphalt and geotextile interlayer on the fracture behavior of unbonded concrete overlay through a laboratory composite beam test. METHODS : In order to evaluate the effect of interlayer materials on the fracture behavior of unbonded concrete overlay, a laboratory test of composite beam was conducted with different types of interlayer. The test results of the composite beam using two types of geotextile interlayer with different thicknesses were compared to the test results of the composite beam using the tradition type of asphalt interlayer. The unbonded concrete overlay on the existing concrete pavement without interlayer was set for the control condition. RESULTS AND CONCLUSION : Overall, the laboratory composite beam test results did show the effect of asphalt and geotextile interlayer on the fracture behavior of composite concrete beams. The three-layer geotextile interlayer and HMA layer both increase the peak load when the first macrocrack occurs in the top concrete beam, while the HMA interlayer causes the smallest load drop percentage after the first macrocrack. The three-layer geotextile did show better performance than the single-layer geotextile through the greater peak load and smaller load drop percentage. It indicates that the thickness of geotextile interlayer will affect the fracture behavior of unbonded concrete overlay and the thicker geotextile interlayer is recommended.

• Journal of Welding and Joining
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• v.25 no.1
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• pp.30-36
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• 2007

A joining of dissimilar metal combination faces significant problems such as poor strength and cracking associated with brittle intermetallic compounds(IMC) formed. An application of laser allows low heat input; leading to less dilution and smaller heat affected zone. The $CO_2$ laser overlay was conducted on an AC2B alloy with feeding Fe-based powders. The overlay area was significantly influenced from the travel velocity rather than the powder feeding rate. The interface between the overlay and substrate consisted of the hard and brittle IMC($FeAl_3,\;Fe_3Al,\;Fe_2Al_5$), which initiating and propagating the crack. The reciprocating test for the slide wear was conducted on a multi-pass overlay experiment. Comparing with the multi-pass overlay with no overlap, the overlay with 50% overlap showed better wear resistance.