국토교통부 보고서 “2022 도로교 현황보고”에 따르면, 국내 교량의 수는 연간 2.9%씩 증가하고 있으며 그에 따라 보수 가 필요한 교량의 수도 늘어나는 추세이다. 교량 하부를 보수할 때 보통은 몰탈을 사용하여 보수해 왔고, 직접 보수하기 에는 작업자의 안전성 및 작업의 효율성이 떨어져 숏크리트를 사용하여 보수해 왔다. 숏크리트는 건식 숏크리트와 습식 숏크리트가 있다. 습식 숏크리트는 시멘트와 골재, 그리고 미리 혼합된 물이 호스를 통하여 이송되고 호스 끝에서 압축 공기가 이를 고속으로 분사하는 공법이다. 다만 재료를 미리 계량하고 배합한다는 한계가 재료 공급의 제약을 가져온다. 건식 숏크리트란 시멘트, 골재, 섬유 등 건조된 재료들이 호스로 빠르게 압송되어 노즐부에서 물과 만나 빠르게 분사되 는 공법이다. 이러한 공법은 장거리 압송 가능, 습식 숏크리트에 비해 상대적으로 적은 장비, 청소와 보수의 용이성, 쉬 운 적용성이 장점이다. 따라서 본 연구에서는 건식 숏크리트 공법을 채택하여 교량 슬래브 하부인 천정부에 대한 단면보 수를 진행하고자 한다. 배합설계는 혼합골재 입도곡선을 고려하고 실리카퓸은 중량의 3%를 차지한다. 연구결과 고압 살 수 및 건식 숏크리트의 현장 적용성은 우수하며, 작업의 용이성 등 교량 하부 구조물 보수에 대한 다양한 장점을 가질 수 있다고 사료된다.

Additive manufacturing is a new approach to design and production. This applies in particular to processes such as repair and rework of selected components. Additive manufacturing can produce almost any shape, and from an MRO part perspective, additive manufacturing offers tremendous advantages. The special feature of additive manufacturing is that it is particularly economical for small-volume production as the number of units is irrelevant compared to the existing manufacturing process. The purpose of this study was started from the MRO point of view, and it Identify changes and respond to the Blisk It is a study on the effect of changing the conditions on the path of the toolpath and the CAM during additive manufacturing using CAM after finding suitable conditions. metal powder.The metal powder withstands various corrosive environments and age hardening occurs very slowly. Inconel 718, which can be used in various applications such as nuclear facility-related parts, aerospace, oil facilities, turbines, and valves, was used. This is SUS 316L with good high temperature strength. The variable of the laser used in the study is the laser power, and the variables on the CAM are Operation, Stepover, Pattern, etc. In the relation between laser power and feed, when feed is specified as 500mm/min, laser power of 700W was most suitable. As for the conditions on NX CAM, ADDITIVE PROFILE Stepover was 0.8mm for Operation, and Infills and Finish for Pattern. When stacking, each layer should be overlapped with the result. Therefore, the stepover should be smaller than the laser spot size and reprocessing should be done in terms of repair, so infills and finish were applied to work larger than the actual product shape.

This paper studied Lee Han-Choel’s career who was known as the first Korean who had participated in several survey and repair projects of Korean historic buildings as a field engineer during the Japanese colonial era. This paper investigated documents and drawings to find out what he had done specifically in the field, and distinguished the records he had written by handwriting comparison method. In addition, the author analyzed the contents of the articles he published and clarified their significance in Korean architectural history. Through this study, the author expected to clarify Lee’s historical status as the first Korean modern expert in the field of historic building conservation, and to supplement the research for the history of Korean during the Japanese colonial era.

울금의 주요 성분인 커큐민과 대두 추출물인 이소플라본의 피부 미용 측면에서 생리활성을 연구하여 화장품 소재로서 가능성 여부를 규명하고자 하였다. 본 연구는 세포실험을 통해 커큐민과 대두 추출물을 피부 세포에 대한 독성 및 항염증을 확인하고, HPLC을 이용하여 대두 추출물의 성분분석과 피부에 적용하였을 때 수분과 유분, 홍반변화를 측정하였다. 본 연구 결과 커큐민이 RAW 264.7 세포에 대한 독성이 적은 것으로 확인되었으며, 항염증에 대한 효과를 확인하였다. 8주 동안 커큐민과 대두 추 출물이 함유된 화장품과 식이를 병행하여 사용하였을 때 수분함량 변화, 유분함량 변화, 홍반 지수의 감 소가 통계적으로 유의미한 변화를 나타내었으며, 여드름 피부에 유의한 효과를 가질 수 있음을 확인하였 다. 따라서 본 연구는 커큐민과 대두 추출물이 화장품 소재로 사용 시 여드름 피부 개선에 효과적인 화 장품 소재로서 활용 가능성이 있을 것으로 사료된다.

The temple Hoeamsa(檜巖寺) was repaired by Naong(懶翁), and with this the power of the temple became far greater to be the greatest Buddhist temple during late Goryeo and early Joseon. Naong’s reconstruction of Hoeamsa was originated from Jigong(指空)’s teaching ‘Samsan Yangsu(三山兩水).’ But it is not clear whether Samsan Yangsu really meant Hoeamsa. By the way, after 14 years, Naong suddenly remembered this word and began to repair Hoeamsa in a large scale. From this, we can guess that Naong tried to give the contemporary Buddhism some change through the repair of Hoeamsa. But, as King Gongmin(恭愍王) the greatest supporter of Naong was suddenly assassinated, the political situation changed a lot and Naong also died unexpectedly. Naong’s death brought out the critical sense to Hoeamsa and, in the process to resolve the crisis, the repair of Hoeamsa began to be justified through diverse religious factors. As these were expanded and developed on and one, Hoeamsa came to be honored as the most divine temple in Korea during the early Joseon dynasty. Furthermore, into the cause structure for the Naong’s repair of Hoeamsa, the influence of Jajang was added through Odaesan Buddhism. As we can well understand, late Silla situation of Jajang and the late Goryeo of Naong were very similar and the both Buddhist leaders should have derived out some religious solution for them. In other words, both of them had a similar recognition in finding the religious solution for the contemporary crises. It becomes a way to understand the Hoeamsa repairing structure taken by Naong and his disciples. Therefore, by comparing the similar religious solution structures given by Jajang and Naong and by clearer understanding on Samsan Yangsu spirit, we can see the repair of Hoeamsa and the related aspects more accurately.

PURPOSES : The evaluation of the pavement condition of the asphalt concrete pavement of No. 2 runway of Inchon International Airport through PMS, a supporting system for making a decision of pavement, maintenance and repair, was made, and the proper time for repair according to the PCI reduction rate was suggested. METHODS: By comparing and analyzing the evaluation results of pavements built in 2009, 2010, 2011, PCI change in each facility (No. 2 runway, C parallel taxiway, connection taxiway) was calculated. By applying the calculated change to PCI deduction rate model, the pavement condition of the target sections was estimated, and then the necessary section and time for repair were chosen. RESULTS: After careful consideration of the time for pavement and maintenance, based on the result of PCI prediction, it was estimated that the southern takeoff and landing section of No. 2 runway was required to be repaired in 2012; connection taxiway in 2013; and C parallel taxiway in 2014; however, the section which is the main moving route of connection taxiway and C parallel taxiway was needed to be repaired in 2012. CONCLUSIONS: For maintenance and repair of airport pavements, the optimal alternative should be chosen by considering economics and operability, via examining the time for repair and the aspect of management all together on the basis of this study.

The electrophoretic deposition process of Ni nano-particles in organic suspension was employed for self-repairing of heat exchanger tubes. For this purpose, Ni nano-particles prepared by levitational gas condensation method were dispersed into the solution of ethanol with the addition of dispersant Hypermer KD2. For electrophoretic deposition of Ni nano-particles on the Ni alloy specimen, constant electric fields of 20 and 100 V were applied to the specimen in Ni-dispersed solution. It was found that as electrophoretic deposition proceeds, the size of the pit or crack remarkably decreased due to the agglomeration of Ni nano-particles at the pit or crack. This strongly suggests that the electrophoretic mobility of the charged particles is larger for the damaged part with a higher current value rather than outer surfaces with a lower current value.

The electrophoretic deposition process of Ni nano-particles was employed for self-repairing of heat exchanger tubes. For electrophoretic deposition of Ni nano-particles on pitted Ni alloy specimen, a constant electric field of 100 V was applied to the specimen for 180 s in Ni-dispersed solution. It was found that as electrophoretic deposition proceeded, the size of the pit remarkably decreased due to the agglomeration of Ni nano-particles at the pit. This strongly suggests that the electrophoretic mobility of the charged particles is larger for the pit with a higher current value rather than outer surfaces with a lower current value.

It is not difficult to see the road repairing. There are many and various machines that can crush road surface. The efficiency and power of the machine depend on crushing head-shape, crushing interval, crushing load, crushing stress, machine's dropping height and roller's kind. The objective of this study is to select the optimal model among ten models of crushing machine with constraints such as crushing depth, variation, and crushed particle size. The data for this study are chosen from the site of construction in Kangnung during three months (2004. 6. 1 ~ 2004. 8. 31). The provided methodology in this paper will be fruitful not only for the selection of crushing machine but also for the aspects of construction period, cost, work efficacy according to the condition from the various sites of construction.

Repaired RC flexural members with ductile cementitious composite are numerically simulated to understand the improved performance in post-peak behavior. Also, stress distributions along steel reinforcements and crack width on the tensile surface are monitored to understand the effect of using ductile cementitious composite as a repair material. The results provide durability characteristics of repaired structures under flexural loading condition.

Smart construction materials have recently been interesting to improve the performance of cement composites and concretes. Especially, no repairing system is required for concrete structures by using self healing concrete, which can close cracks on concrete by itself. Mineral admixtures, capsules and bacteria are the most used for self healing concrete technology. In this study, high strength concrete with mineral admixtures were utilized to develop self healing capacity. Comparison with water flow test and image captures were conducted.

Chloride attack is one of the most critical deterioration due to rapid corrosion initiation and propagation which can cause structural safety problem. Extended service life through repairing is very important for determination of maintenance strategy. Conventionally adopted models for estimation of LCC (Life Cycle Cost) have shown step-shaped elevation of cost, however the extension of service life is much affected by quality of construction and repairing materials, which means engineering uncertainties in residual service life. In the paper, RC (Reinforced Concrete) column with three different mix proportions exposed to chloride attack are considered, and repairing numbers with related costs are evaluated through probabilistic technique for maintenance. When calculating repair frequency for intended service life through probabilistic model, the required repair frequency is evaluated to be 6.71 times for OPC, 4.09 times for SG30, and 2.95 times for SG 50, respectively. The probabilistic model for repairing cost is evaluated to be effective for reducing the repair frequency reasonably with changing the intended service life and design parameters.

This paper presents the surface-wave based non-destructive evaluation on crack repairing performance in concrete. Concrete specimens with different crack depths and identical compositions were prepared for surface wave transmission experiments. Cracked concrete specimens were perfectly repaired through epoxy injections, and recovery of transmission coefficients and spectral energy were confirmed in process of crack repairing. Additionally, the effectiveness and feasibility of spectral energy based assessment techniques for the evaluation of crack in concrete is also investigated.

염해에 따라 발생하는 보수시기와 보수로 유지되는 내구수명은 보수비용 평가에 매우 중요한 요소이다. 일반적으로 사용하는 결정 론적 보수비용 평가는 사용기간의 연장에 따라 계단식으로 증가하게 되며, 보수로 인해 변동되는 내구수명의 변화를 고려하지 못한다. 본 연구 에서는 확률론적인 보수시기 및 비용을 평가하기 위해, 염해에 노출된 콘크리트 교각을 선정하였다. 두 가지 배합과 염화물에 노출된 외부 환 경조건을 고려하여 염화물 거동을 평가하였으며, 도출된 내구수명과 수명에 대한 확률변수를 변화시키면서 보수시기 및 비용 변화를 분석하 였다. 변동계수의 변화에 따른 보수회수는 큰 차이가 발생하지 않았으나, 초기의 내구수명 연장이 구조물의 보수시기 및 비용에 큰 영향을 미 치고 있었다. 또한 확률론적 보수비용 산정 모델은 결정론적 모델과 다르게 연속적인 보수비용이 평가되므로 목표내구수명에 따라 보수회수 를 감소시킬 수 있는 효과적인 기법임을 규명되었다.