• Journal of the Korean Society for Railway
• /
• v.5 no.2
• /
• pp.27-33
• /
• 2002

궤도의 역할은 열차 하중을 지지하고, 이것을 분산시켜 구조물에 전달함과 동시에 열차의 주행을 위한 원활한 (안전하고 승차감이 좋은) 안내로를 제공하는 것이다. 그러나, 궤도는 열차의 반복 주행에 의하여 구성 재료의 열화ㆍ손상이나 궤도 틀림의 진행이 부득이 하므로 일상적인 궤도정비 작업이나 재료교환 작업을 피할 수 없기 때문에 될 수 있는 한 적은 보수비로 열차 주행에 필요한 궤도 품질을 실현하는 기술의 확립이 궤도 기술에 관한 연구 개발의 최대 사명이다. 궤도 보수에 관계하는 비용은 크게 세 가지로, 즉 궤도 재료의 교환ㆍ보수 작업, 궤도 틀림의 정비 작업, 각종 검사나 유간 정정 등의 기타 작업으로 대별할 수 있다. (중략)

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.11 no.4
• /
• pp.458-466
• /
• 2023

Structures in our surroundings deteriorate over time due to environmental and chemical factors, resulting in a decrease in their performance. The primary causes of degradation in concrete structures are carbonation, salt damage, and freeze-thaw cycles. Various maintenance methods exist to address these degradation issues. However, research and technological development for existing maintenance methods have been ongoing, but the accuracy and effectiveness of repair materials and techniques have not been extensively validated. Therefore, in this study, we conducted a material performance evaluation of various manufacturers' repair materials. Based on this evaluation, we applied corrosion inhibitors and epoxy, which are the methods most closely related to crack repair, to assess the durability performance against carbonation, salt damage, and freeze-thaw cycles. The results show approximately a two-fold performance improvement against carbonation and salt damage, and a 5% enhancement in repair performance against freeze-thaw cycles. Thus, it is considered effective in preventing rebar corrosion when appropriate maintenance is carried out according to environmental and chemical factors during structural repairs.

• Journal of the Korea Concrete Institute
• /
• v.19 no.1
• /
• pp.39-46
• /
• 2007

In this study, for the establishment of the performance evaluation methods and the quality control standards of durability recovery method, the quantitative exposure data by long term exposure test under the coast and normal atmosphere is accumulated and analyzed. Investigating and evaluating the result of exposure test during 30 months of exposure age under the coastal and normal atmosphere environment, carbonation depth and chloride-ion penetration depth very little penetrated than cover depth. It seems reasonable to conclude that main cause of Corrosion of reinforcing bar are chloride-ion and macro cell from the result of corrosion area and corrosion velocity. Therefore, it is considered to be applied as the fundamental data on the performance evaluation and quality control standards of repair material and method through continuous exposure test in the future.

• Fire Science and Engineering
• /
• v.33 no.3
• /
• pp.105-111
• /
• 2019

In Korea, the results of a field survey on the construction of flammable exterior materials implemented in 2018 revealed that 147,559 buildings belong to this category. It was found that the fire spreading cases in upper and adjacent constructions are about 3,500 per year, the fires of starting in flammable exterior material are about 1,500 per year. In this study, we investigated the repair method of buildings constructed by flammable exterior material and conducted performance verification of each repair materials for prevention of similar fire. In the case of the repair method, a method of reinforcing with a repair material after removing the existing building finishing material and a method of attaching the repair material after performing the face finishing are proposed. In addition, we conducted cone calorimeter tests of 6 materials such as fireproof gypsum board, mineral wool, hard urethane foam, ceramic board and ALC panel as dryvit and repairing materials, and investigated basic combustion performance of that materials.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.6
• /
• pp.176-181
• /
• 2018

Concrete structures are degraded physically and chemically due to various reasons after construction. Because the deterioration of concrete structure reduces the service life, reasonable repair and maintenance techniques are needed. Recently, in order to efficiently repair concrete structures, many researches on hybrid repair materials having improved adhesion performance have been carried out actively. In this study, we developed a hybrid repair material containing rapid hardening cement, PVA powder, nylon fiber, and latex to improve adhesion and water-tightness of existing concrete. The compressive strength, drying shrinkage and the adhesion strength test were carried out to evaluate the performance of the repair material. In addition, the flexure bond performance was evaluated before and after repair. From the results, the bending strength was 110% ~ 150% in all specimens except for the specimen containing only the rapid hardening cement, and all the specimens behaved with the existing concrete in the crack pattern generated by the bending strength.

• Magazine of the Korea Concrete Institute
• /
• v.7 no.6
• /
• pp.233-241
• /
• 1995

In this thesis, the fatigue tests were performed on a series of R /C beams repaired with co& crete-lmlyrner composites to investigate the fatigue bahavior. The three point loading system is used in the fatigue tests. In these tests, relations between the repeated loading cycles and mid-span deflections, number of repeated loading cycles when repaired beams were fractured, the bonding performance of repair materials were observed. On this basis, the mid-span deflections, the crack growth and failure mode of repaired R /C beams were studied. A S-N curve was drawn to present the fatigue strength of repaired beams. From the test results, it was shown that behavior of R /C beams repaired with polymer-cement series were very sirnillar to control beam about bonding performance, mid-span deflections and fatigue strength according to S-N curve drawn by the regression anlysis on the fatigue test results.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.285-285
• /
• 2015

댐 및 저수지 시설물은 노후화나 안전성 미확보로 인한 파손 또는 붕괴 발생 시 하류부에 막대한 인명과 재산피해 등 치명적인 결과를 초래하게 된다. 이러한 대형 안전사고를 예방하고자 시설물의 안전관리에 관한 특별법에서는 댐 시설물을 규모별로 1, 2종 시설물로 구분하고, 이에 대해 주기적으로 안전점검 및 정밀안전진단을 실시하도록 제도화하는 한편 진단 결과에 따라 보수 보강 등의 안전조치를 의무화하고 있다. 구조물 결함에 따른 보수 보강은 보수재료와 공법 선정시 공법의 적용성, 구조적 안전성, 경제성 등을 종합적으로 검토하여 결정하여야 한다. 손상 부위에 대한 보수 보강은 제한된 예산과 인력을 효율적으로 투자하기 위해 보수재료 및 공법의 선정 뿐만 아니라 보수 보강이 이루어져야 하는 부재에 대한 우선순위를 산정하는 것이 최우선적으로 선행되어야 한다. 안전점검 및 정밀안전진단 세부지침에서는 보수 보강 대책 마련 시안전점검 및 정밀안전진단 결과를 기초로 하여 적정 재료 및 공법을 선정하고, 보수 보강의 수준 및 우선순위를 결정하도록 명시되어 있다. 하지만 우선순위 결정에 대한 가이드라인이 부재하여 불필요한 시공과 비효율적인 예산 투입으로 인해 국가예산의 낭비되고 시설물의 안전까지 위협받게 되는 경우가 발생하고 있다. 따라서 본 연구에서는 시설물의 상태에 따른 적절한 보수 보강 필요성을 판단하고 보수 보강 수준 및 우선순위를 결정하기 위한 방법론을 개발하였다. 댐 시설물에 대한 안전점검 및 정밀안전진단의 종합평가는 평가대상 개별시설에 대하여 상태 평가 및 안전성 평가를 실시한 후 그 결과에 의해 산출된 상태평가지수와 안전성평가지수를 비교하여 평가단계별로 그 결과를 취합하여 종합평가를 실시하고 있다. 따라서 상태평가에 의해 산정된 종합평가 결과를 이용하여 개별 부재의 상태평가값 산정을 위해 하부 단계의 가중치 및 평가 지수 역산하고, 재산정된 가중치 및 평가지수를 이용하여 각 부재에 대한 보수 보강 우선순위를 산정하고자 하였다. 개발된 방법론은 점검 진단 책임기술자 및 시설물 관리주체 담당자가 댐 시설물의 개별부재에 대한 보수 보강 실시 여부를 판정할 수 있는 기준으로, 보수 보강에 대한 정책 결정시 경제성을 고려한 신뢰도 있는 기준으로 활용될 수 있을 것으로 기대된다.

• International Journal of Highway Engineering
• /
• v.14 no.3
• /
• pp.59-67
• /
• 2012

This study presents the evaluation of the patching materials that are used to repair the distress of asphalt pavement. Four kinds of patching materials currently used in practice were tested in both laboratory and field. The laboratory tests included the dry and soaked Marshall stability test, indirect tensile test, wheel tracking test and adhesive strength between the asphalt pavement and the repairing material was tested as a performance test. The field study was conducted using the slab samples placed on the location of vehicle tire passing and the performance of the repairing materials were investigated as passing the traffic load. The result of the laboratory tests were satisfied with the current design criteria and material standard except for water-immersion stability. Type C patching material showed the highest adhesive shear strength among the patching materials tested. However, the mature distress, such as rutting and stripping were monitored after construction in 10 days. It was found that performance of patching material is lack of quality behavior when they were applied in the field and required to develop and applu to prevent the mature distress of the current patching materials.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.10 no.1
• /
• pp.123-130
• /
• 2006

The duties of the restorative materials are to bear up against stress and to protect reinforcement corrosion. So the restorative materials are estimated by various kinds of strength, permeability and etc, But, in case of existing performance evaluation of restorative materials, because various deterioration factors are separately acted, the system of performance evaluation is different from that of combined deterioration of real structure and it is difficult to evaluate the exact performance of restorative materials. In this study, to evaluate Performance of restorative materials, we compare their korea standard properties in terms of compressive and bending strength and permeability of water and air with real durability for carbonation, salt damage and actual reinforcement corrosion like ratio of corrosion area. weight reduction and corrosion velocity of steel bar under environment of combined deterioration. The results showed that strength and permeability of restorative materials are similar but their resistance to carbonation, salt damage and actual reinforcement corrosion are very different.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.36 no.4
• /
• pp.715-722
• /
• 2016

Most of the domestic railroad tracks are ballast track and repetitive maintenance is required in this track. Therefore, it is necessary to optimize maintenance process for maintenance cost reduction and more effective maintenance. For this, it is important to develop a reasonable settlement progressive model of ballast layer. However, the behavior of ballast is different to that of soils, since ballast is composed of large coarse gravel. Thus, in this study, we carried out numerical analysis by using the discrete element method (PFC 2D) for better understanding of ballast settlement and development of reasonable settlement progressive model. And, we evaluated the settlement of ballast according to particles shape, porosity and loading conditions.