• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2017.11a
• /
• pp.41-42
• /
• 2017

In this study, an investigation was made to study the chemical resistance performance of epoxy resin injection type leakage repair material used in the Korean construction market in accordance to the test method outlined in "ISO TS 16774, Part 2; Test Method for Chemical Resistance." This is a new standard document used for quality control method of injection type repair material used for leakage cracking of underground concrete structures. The results of this study can be expected to be utilized as reference data that can be used for quality improvement of the maintenance methods for future construction.

• Journal of the Korean Data and Information Science Society
• /
• v.16 no.2
• /
• pp.263-270
• /
• 2005

The reliability guarantee insurance policy for parts and materials was introduced to the market in 2003. This policy indemnifies manufactures for the repair/failure costs, recall expenses. In this paper, owing to the nature of the policy, we propose a new rate-making system considering the type of product and industry, quality control circumstances, record of guarantee performance, and exposures.

• Korean Journal of Metals and Materials
• /
• v.46 no.4
• /
• pp.241-248
• /
• 2008

Gas turbine blades serviced for a period are usually repaired for reuse via "rejuvenation processes" including fluoride ion cleaning, brazing or welding, and recoating. Among these processes, the welding process is applied to rebuilt damaged parts of the blade in which welding materials being mostly Ni base superalloy are supplied in the form of powder or wire. When powder is used in the welding process, the uniform supply of powder is a very important factor for the uniformity of welding. According to our experience, the uniformity was very poor with the powder supply system only utilizing pressurized air flow. A new powder supply system was developed in which powder is supplied via air flow and simultaneously mechanically. The welding uniformity was much improved with this new system. In this study, the microstructure and mechanical properties of welded parts obtained from several kinds of powder using the new powder supply system were characterized.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2014.05a
• /
• pp.76-77
• /
• 2014

Stone is one of the oldest and most popular materials used on the external wall because of its durability, abundance and aesthetic effect. However, there are two main problems in the existing pin hole construction method. One is uniformity of construction quality, and the other is a repair work of stone panels. Therefore, a new method is needed to overcome these problems. This paper presents a new stone curtain wall system using under cut anchor and secondary holes that was developed by authors. The improved quality and reduction of construction period can be obtained by this system.

• Journal of architectural history
• /
• v.11 no.3 s.31
• /
• pp.35-51
• /
• 2002

This study is about the preservation of wooden buildings as cultural properties. I got the idea for preservation and repair of cultural properties of wooden buildings by watching the process of repairing them in Japan. The Japanese have been endeavored to restoring old wooden buildings to their original forms for more than a hundred years. The idea to change decayed materials into new materials or the new approach to the process of restoration used to be in conflict with the concept of 'Authenticity'--the criteria for evaluation of the value of cultural properties, based on the Western of thinking, established by UNESCO. Since 'Nara Conference on Authenticity', held in 1994 in Nara, however, the concept of 'Authenticity' has changed, and the peculiarity of certain cultural properties of the wooden buildings and their diversity of culture have now begun to be recognized by UNESCO. This is a crucial change for the study of preservation, repair and restoration of cultural properties of wooden buildings. The purpose of this study is, therefore, to look closely at the process of change of the concept 'Authenticity' and find a better method for preservation of cultural properties of wooden buildings.

• Journal of the Korea Institute of Building Construction
• /
• v.19 no.5
• /
• pp.411-419
• /
• 2019

Underground concrete structures are constructed under a geographical environment called underground and exposed to various environments that promote deterioration. Among them, groundwater promotes deterioration of underground concrete structures due to contaminated water from the ground. In this study, the chemical resistance performance test evaluation of five different receptors for a total of 15-type leakage repair materials of five series was conducted to determine the chemical stability of the leakage repair material used in the crack area. The results show a general increase and decrease in most chemical receptors, but the biggest increase and decrease was shown in acrylic systems, which were found in sodium chloride and sodium hydroxide, and epoxy was found in hydrochloric acid. The cement system is showing a lot of increase and decrease in sodium chloride. It is expected that the results of these studies will be used as a basis for chemical stabilization in the development of new materials.

• Tribology and Lubricants
• /
• v.38 no.3
• /
• pp.93-100
• /
• 2022

Micro-light emitting diode (micro-LED) displays offer numerous advantages such as high brightness, fast response, and low power consumption. Hence, they are spotlighted as the next-generation display. However, defective LEDs may be created due to non-uniform contact loads or LED alignment errors. Therefore, a repair process involving the replacement of defective LEDs with favorable ones is necessitated. The general repair process involves the removal of defective micro-LEDs, interconnection material transfer, as well as new micro-LED transfer and bonding. However, micro-LEDs are difficult to repair since their size decreases to a few tens of micron in width and less than 10 ㎛ in thickness. The conventional nozzle-type dispenser for fluxes and the conventional vacuum chuck for LEDs are not applicable to the micro-LED repair process. In this study, transfer conditions are determined using a micro stamp for repairing micro-LEDs. Results show that the aging time should be set to within 60 min, based on measuring the aging time of the flux. Additionally, the micro-LEDs are subjected to a compression test, and the result shows that they should be transferred under 18.4 MPa. Finally, the I-V curves of micro-LEDs processed by the laser and hot plate reflows are measured to compare the electrical properties of the micro-LEDs based on the reflow methods. It was confirmed that the micro-LEDs processed by the laser reflow show similar electrical performance with that processed by the hot plate reflow. The results can provide guidance for the repair of micro-LEDs using micro stamps.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.797-800
• /
• 2008

The pre-mixed concrete shotcrete, which can pre-bag the shotcrete materials and thus can save considerable labor activity, will be developed through extensive experiments. The proposed pre-mixed High performance Shooting concrete system included hydro-demolition will be verified though field tests in actual repair and rehabilitation construction sites. This research was on developing of the High performance Shooting concrete by evaluation of site application by field test using new automatic Hydro-demolition and Shotcrete equipment.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.7 no.1
• /
• pp.217-225
• /
• 2003

Grouting internally with grout materials can repair the micro-cracks and micro-voids of construction joints more efficiently than injecting grouts from the surface of cracks. A new internal grouting method using perforated bundled-cables was developed in this study to enhance the structural integrity of the construction joints. The extensive experiments were performed to examine the mechanical behavior of construction joints which are repaired internally by the developed method. The tests were conducted for rectangular-shaped box wall structures and straight wall structures. The strength and permeability tests at grouted construction joints were conducted to evaluate the structural behavior of repaired construction joints. The present study indicates that the internal grouting method developed in this study enhances greatly the performance of construction joints and may be efficiently used for the leak-tight integrity of construction joints in concrete structures.

• Journal of the Korea Concrete Institute
• /
• v.11 no.3
• /
• pp.13-21
• /
• 1999

Recently, many strengthening methods are developed to repair damaged structures, especially, steel plate or carbon fiber sheet bonding methods are widely used. For the bonding methods, the strengthening materials are bonded when the original structure is under loading, with causes the difference of initial stresses between original member and bonded material. However, current design method or theory, which mostly depends on ultimately strength design, cannot account the difference of initial stresses between members, and it disregards the reduction of nominal strength. In this study, a new strengthening design theory and program which can account the difference of initial stresses are developed, and applied to the case when a structure in service is repaired. In order to verify the validity of the theory and the program, a test result is referred and compare with the results and it is showed that the calculated values are almost same as the referred data and finally proved that the program is reliable. The results showed that the amount of strengthening material depends on the status of damages of structure, and the nominal strength is reduced depending on the degree of damages.