• Proceedings of the KWS Conference
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• 2007.11a
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• pp.196-198
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• 2007

Laser cladding technology was studied as a method for upgrading the present repair procedures of damaged tubes in a nuclear steam generator and Doosan subsequently developed and designed a new Laser Cladding Repair System. One of the important features of this newly developed Laser Cladding Repair System is that molten metal can be deposited on damaged tube surfaces using a laser beam and filler wire without the need to install sleeves inside the tube. Laser cladding qualification tests on the steam generator tube material, Alloy 600, were performed according to ASME Section IX.

• Journal of the Korean Society for Railway
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• v.12 no.1
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• pp.110-114
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• 2009

This study is for the evaluation of compressive strength restoration of sandwich composite laminates with adhesively bonded scarf patches. It was used in this study that the sandwich composite laminate with an aluminum honeycomb core and CF1263 woven fabric carbon/epoxy faces was applied to the car body structure for Korean tiling train. In this study, it was damaged by low velocity impact and repaired using scarf repair method. Then, the compressive strength restoration of assessed by compressive after impact (CAI) test. From the test, it could be known that the compressive strength was restored up to 72% by only scarf repair method and 91% applied by an extra ply over the undamaged one.

• Korean Journal of Heritage: History & Science
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• v.53 no.2
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• pp.140-155
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• 2020

The purpose of this study is to examine historical wall repair details through analysis of repair data and administrative documents of the Paradise Conservation of Gangjin Muwisa Temple. In addition, the purpose of the project is to examine the differences and commonalities between the materials and construction technology used in the building's walls. The data for repair work conducted in 1935, 1956, and 1982~3 was analyzed and the results of the research were as follows. First, data for the wall construction conducted in 1935 during the dismantling repair showed that the interior structure of the wall was found to follow that of the original, but the first, second, and final layers used different materials. The composition material of the wall consisted of clay, lime and sand, the second layer used sand and plaster, and the last layer used plaster and seaweed paste. Second, the structure of the wall interior, which was found during the 1956 repairs, consisted of wood woven horizontally and vertically. It was confirmed that this had been installed diagonally using a rope. Third, the 1982~3 repair work confirmed that the wall's interior construction conformed to the original method. The lime-sand wall was formed by mixing slacked lime, sand, soil, fodder, and seaweed grass. Fourth, when the various repairs are considered as a whole, it is clear that the interior structure of the wall was made more than 1900 years ago, and the material used in the wall changed in 1935. Fifth, the materials used for each repair differed, but each project had a common view of cultural heritage repair principles in sections that stated the significance of each project.

• International Journal of Safety
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• v.10 no.1
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• pp.16-21
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• 2011

In this thesis, appearance inspection, compressive strength of concrete test, arrangement of bar inspection, survey, and bearing stress analysis were performed on a damaged coping of reinforced concrete pier to investigate the damage cause. According to the performed a series of inspections, it was found that the coping of pier was damaged during PSC (Pre-stressed Concrete) beam construction. In this thesis, the repair method for damaged pier was studied. The repair procedure used in this thesis was follows : chipping for damaged part, clean by high-pressure, installation of wire mesh, coating of surface hardening, construction of section restoration material, copula grinding, and prevent coating for far-infrared radiation.

• Nuclear Engineering and Technology
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• v.39 no.3
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• pp.231-236
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• 2007

Due to the occasional occurrences of stress corrosion cracking(SCC) in steam generator tubing(Alloy 600), degraded tubes are removed from service by plugging or are repaired for re-use. Since electrodeposition inside a tube does not entail parent tube deformation, residual stress in the tube can be minimized. In this work, tube restoration via electrodeposition inside a steam generator tubing was performed after developing the following: an anode probe to be installed inside a tube, a degreasing condition to remove dirt and grease, an activation condition for surface oxide elimination, a tightly adhered strike layer forming condition between the electro forming layer and the Alloy 600 tube, and the condition for an electroforming layer. The reliability of the electrodeposited material, with a variation of material properties, was evaluated as a function of the electrodeposit position in the vertical direction of a tube using the developed anode. It has been noted that the variation of the material properties along the electrodeposit length was acceptable in a process margin. To improve the reliability of a material property, the causes of the variation occurrence were presumed, and an attempt to minimize the variation has been made. A Ni alloy electrodeposition process is suggested as a primary water stress corrosion cracking(PWSCC) mitigation method for various components, including steam generator tubes. The Ni alloy electrodeposit formed inside a tube by using the installed assembly shows proper material properties as well as an excellent SCC resistance.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.801-809
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• 2000

Until recently as a method of repairing leaking problem, generally urethane series were used for many structures as subway, box culvert etc. However the lacking of sufficient penetration capacity have made it difficult to repair such structures completely. Now, we could achieve enhanced quality of repairing work by using new material which was compounded of urethane series and cement series properly. This material can penetrate concrete structure efficiently and move interactively with the structure in case of the thermal expansion. Besides of this, we could prevent expecting leakage through several improvements on the aspects of design, materials and site implementation.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.2
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• pp.279-288
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• 2017

The Material Transportation Capability Analysis Method in North Korea includes adversary's activities such as destruction of bridge which is one kind of choke points in the road network and surprise attack against resupply march unit. Also, the amount of damage on choke points in the road network and repair time depending on repair unit commitment must be reflected. In this study, a scenario encompassing plausible resupply transportation circumstances while counterattacking into NK will be established. Then, based on such scenario, a simulation model will be established and the result of simulation will be compared to the results of numeric example which has been used in the ROK Army. We demonstrate, through a certain Corps operation area, that the Scenario-based Simulation Model results predict the performance of resupply operation very well. Therefore, it makes sustainment planners and commanders do activities which is suitable for battlefield and should be used in the real situation. It is also a stochastic model.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.397-400
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• 2006

Most of the civil structures in Korea and abroad have many kinds of damages when they are facing over-loaded traffics, long-term serviceability, and severe environmental conditions. Repair, rehabilitation, and retrofit are important for maintaining the serviceability of structures. In recent year, VES-LMC has been widely used as repair material for bridge deck repair and rehabilitation, because the VES-LMC has a various benefits such as traffic opening after 3 hours of curing, higher durability and bond strength. In case of any structure repaired or rehabilitated with VES-LMC, those were influenced capacity of bond between the base layer of slab and VES-LMC as well as physical properties of each other materials. The capacity of bond depended on purity of interface, micro cracks, curing of VES-LMC and so like. A kind of popular concrete repair technique, High pressure water jetting equipment is extremely efficient at removing damaged concrete. Removing damaged or poor quality concrete from sensitive structures such as bridge, tunnels, multi-story car parking decks and runways, using the high pressure water jetting could remove damaged or poor quality concrete remaining healthy and sound concrete. Accordingly, the purpose of this study is that it was to evaluate effect of hydrodemolition on the bond strength of VES-LMC overlay compared with effects of other method such as breaker, untreated. Also, it was evaluated the effect of surface moisture.

• Steel and Composite Structures
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• v.9 no.3
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• pp.209-221
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• 2009

Heating correction, through heating and flattening a structure with a pressing machine, is the in-situ method used to repair buckled steel structures. The primary purpose of this investigation is to develop an FEM model which can predict the mechanical response of heat-corrected plates accurately. Our model clarifies several unsolved problems. In previous research, the location of the imperfection was limited to the center of the specimen although the mechanical behavior is strongly affected by the location of the imperfection. Our research clarifies the relationship between the location of the imperfection and the mechanical behavior. In addition, we propose further reinforcement methods and validate their effectiveness. Our research concludes that the strength of a buckled specimen can be recovered by heating correction and the use of an adequate stiffener.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.7 s.184
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• pp.101-107
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• 2006

Cold gas dynamic spray or cold spray is a novel manufacturing method for coatings. Cold spray is a high rate and direct material deposition process that utilizes the kinetic energy of particles sprayed at high velocity (300-1,200m/s). In this research, a technique to repair the damaged mold by cold spray deposition and mechanical machining was proposed. An aluminum 6061 mold with three-dimensional surface was fabricated, intentionally damaged and material-added by cold spray, and its original geometry was re-obtained successfully by Computer Numerical Control (CNC) machining. To investigate deformation of material caused by cold spray, deposition was conducted on thin aluminum plates ($100mm{\times}100mm{\times}3mm$). The average deformation of the plates was $205{\sim}290{\mu}m$ by Coordinate Measurement Machine (CMM). In addition, the cross section of deposited layer was analyzed by scanning electron microscopy (SEM). To compare variation of hardness, Vickers hardness was measured by micro-hardness tester.