• Structural Monitoring and Maintenance
• /
• 제2권1호
• /
• pp.35-48
• /
• 2015

The main objective of this study is to evaluate the long-term performance of various concrete composites in natural marine environment prevailing in the Gulf region. Durability assessment studies of such nature are usually carried out under aggressive environments that constitute seawater, chloride and sulfate laden soils and wind, and groundwater conditions. These studies are very vital for sustainable development of marine and off shore reinforced concrete structures of industrial design such as petroleum installations. First round of testing and evaluation, which is presented in this paper, were performed by standard tests under laboratory conditions. Laboratory results presented in this paper will be corroborated with test outcome of ongoing three years field exposure conditions. The field study will include different parameters of investigation for high performance concrete including corrosion inhibitors, type of reinforcement, natural and industrial pozzolanic additives, water to cement ratio, water type, cover thickness, curing conditions, and concrete coatings. Like the laboratory specimens, samples in the field will be monitored for corrosion induced deterioration signs and for any signs of failureover initial period ofthree years. In this paper, laboratory results pertaining to microsilica (SF), ground granulated blast furnace slag (GGBS), epoxy coated rebars and calcium nitrite corrosion inhibitor are very conclusive. Results affirmed that the supplementary cementing materials such as GGBS and SF significantly impacted and enhanced concrete resistivity to chloride ions penetration and hence decrease the corrosion activities on steel bars protected by such concretes. As for epoxy coated rebars applications under high chloride laden conditions, results showed great concern to integrity of the epoxy coating layer on the bar and its stability. On the other hand corrosion inhibiting admixtures such as calcium nitrite proved to be more effective when used in combination with the pozzolanic additives such as GGBS and microsilica.

• 한국진공학회지
• /
• 제12권2호
• /
• pp.93-104
• /
• 2003

저진공펌프의 내구성평가와 관련하여 펌프의 성능이나 상태의 저하에 관한 기술적 근거를 확보함으로써 펌프의 운전상태를 진단할 수 있는 기초기술을 확보할 수 있으며, 이는 진공펌프의 기계적 결함 및 성능평가 장치의 동적 응답과 신뢰도 구축에 중점을 두고 신호 분석을 통하여 실험적으로 기계적인 동적 특성을 확인하는 과정을 통하여 수행할 수 있다. 저진공펌프의 압축일에 소요되는 전력을 이론적으로 규명하고 펌프의 압축일을 계산하였으며, 소비전력에 대한 진공펌프의 에너지 효율을 예측하여 펌프 노화에 따르는 소비전력의 증가 원인을 규명하는 자료로 활용할 수 있다. 또한 저진공펌프의 가동 중에 측정한 진동, 압력신호, 배기속도 및 소비전력을 측정하고 분석하여 펌프 운전상태를 감시하는데 매우 유용한 인자가 무엇인지 확인하였으며 추후 연구의 방향과 내구성평가의 기초기술을 확보하였다.

• 대한토목학회논문집
• /
• 제37권6호
• /
• pp.1043-1051
• /
• 2017

노후 된 도로 포장 개량을 위한 아스팔트 덧씌우기 포장의 경우 반사균열로 인한 조기파손이 문제가 되고 있어, 반사균열을 억제하고 포장의 내구성을 확보할 수 있는 새로운 공법이 필요한 실정이다. 에폭시 아스팔트 바인더를 이용한 응력흡수층(SAMI)을 통해 아스팔트 덧씌우기 포장의 내구성을 확보하고자 하였다. 에폭시 응력흡수층의 인장성능, 접착성능, 방수성능, 내화학성, 내구성 실험을 수행하였으며, 교면 방수재료의 품질기준을 만족하는 것으로 나타났다. 반사균열 억제 효과를 검토하기 위해 반복직접인장실험 결과 에폭시 응력흡수층 적용시 단면 두께가 감소하여도 두께 10cm의 PSMA 아스팔트 콘크리트에 비해 1.2~1.56배 높은 반사균열저항성을 나타내었다. 4점 빔피로 실험 결과 에폭시 응력흡수층을 적용하면 피로파괴횟수가 약 7.5배 높아져 포장의 내구성을 향상시킬 수 있었다. 에폭시 응력흡수층은 반사균열 억제와 피로수명 향상 및 방수층으로서의 역할을 수행하여 아스팔트 덧씌우기 포장의 내구성 향상에 효과가 있는 것으로 나타났다.

• 한국도로학회논문집
• /
• 제10권2호
• /
• pp.115-124
• /
• 2008

본 연구에서는 단지 내 아파트 블록포장 50곳의 현장조사를 통하여 주요 파손형태를 조사하여 공용성을 평가하였다. 공용성 평가결과에 따르면, 조사대상지역에서 9년의 공용연수를 가진 블록포장의 유지관리지수는 7.9에서 8.9사이이며, 블록포장의 상태는 양호한 것으로 나타났다. 따라서 건설교통부 '보도설치 및 관리지침'에 10년으로 제시된 보도의 교체주기는 검토할 필요가 있다는 결론을 도출하였다. 또한 블록포장의 공용성을 객관적으로 평가하기 위해서 일본블록포장협회에서 제시한 유지관리 기준과 건설교통부 '보도설치 및 관리지침'의 유지관리기준을 조합하여 국내 현실에 적합한 유지관리기준을 제시하였다. 외국과 비고할 때 국내의 블록포장의 기준에는 내구성 관련기준과 줄눈채움재 및 모래안정층의 품질관리 기준이 명확히 제시되어 있지 않다. 따라서 블록포장의 기대수명과 유지관리비용을 줄이기 위하여, 본 연구에서는 국내외 기준을 비교하여 이러한 기준들을 국내기준에 포함시킬 것을 제안하였다.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2009년도 춘계 학술논문 발표대회 학계
• /
• pp.45-48
• /
• 2009

The performance of concrete mainly depend upon its water-cement ratio. If water percentage is excess in concrete, it may cause the degradation of performance. Because of these reasons, the change of water content is managed by using various evaluation method of unit water content. And criterion for the change of water content is regulated and used. However the criterion is set only considering production error and measurement error but criterion does not consider performance degradation of concrete. Therefore this study tries to investigate degradation of performance while adding extra water by artificial manipulation or management error in concrete, The contents of extra water for tests are set as 0, 20, 40, 60kg/m3, to examine the performance degradation of concrete, strength, shrinkage, cracks, carbonation are tested This study conclude that, when extra water content is excess than 20kg/m3 in concrete, then performance level of concrete declined rapidly. 80 it is very important to maintain quality of concrete for its better performance.

• 동력기계공학회지
• /
• 제15권3호
• /
• pp.12-17
• /
• 2011

Gears are useful for power transmission due to excellent power transmission performance, low cost, and compactness. In addition, gears have constant speed ratio, compact structure, and excellent efficiency. In order to transmit higher power, the new multi-range transmission requires gears which have greater strength than the existing transmission. This study evaluates stability and durability through gear analysis of the multi-range transmission in commercial vehicles using ROMAX-DESIGNER program. Also, strength design evaluation is carried out by the analysis results which are compared with gear strength theory of AGMA standard. Bending stress and contact stress on gears are lower than their allowable stresses. Therefore, we can evaluate the safety of the gear strength design in multi-range transmission.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2001년도 학술논문발표회
• /
• pp.70-75
• /
• 2001

There is a problem to be solved for improvement of durability and safety for concrete When the waterproofing and anticorrosive work of main concrete are design, the material a of construction need to be correctly applied to appropriate circumstance conditions. Epoxy mostly been used for concrete water tank structure. Lately, lots of subjects on adaption res in mortar for waterproofing and anticorrosive are under discussion. Then, we attempt to approach by evaluating and comparing every capabilities with waterproofing materials in this experiment. Capability evaluation items include the bond age and curing conditions, the bond strength after accelerated weathering test and fret impact resistance, a mount of water, seepage quan Through the experiment analysis, we found that waterproofingtity, drinking water chemicals resistance. and anticorrosive resin mortar used with glass fiber cloth, inorgar material is dominantly superior to other waterproofing materials. According to this paper, we suggest the resin mortar as a new surface treatment material water tank structure.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
• /
• pp.19-20
• /
• 2019

The purpose of this study is to apply a test method that evaluates durability under wet environment rather than the strength of the material itself to reflect the environment of use and field conditions of silic acid powder applied waterproof material, and to prepare a foundation data for differentiated performance criteria through test verification.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
• /
• pp.81-85
• /
• 2004

This paper describes the testing facility to demonstrate the performance of the distribution class circuit breakers and switchgears and the testing methods. The field-test evaluation system consists of two parts. One is the distribution system for simulation of the condition on interruption mode of switches which are installed in the system and tested by the AFG(Artificial Fault Generator) and the thunderbolt generator just like in the real field. The other is a laboratory for confirmation or the important characteristics regarding to the insulation, gas, environment durability of equipment. For the fatal failure mode, a FMEA(Failure Modes and Effects Analysis) technique which is a kind of a structural analysis to consider a counter-plan was emploved.

• 품질경영학회지
• /
• 제25권2호
• /
• pp.169-188
• /
• 1997

The purpose of this study is concerned with suggesting a new a, pp.oach to evaluating the overall product quality in the sense of the relative efficiency of products, whose quality is measured with 8-dimensional attributes, suggested by Garvin. The attributes included 8 quality measures, that is, performance, features, reliability, conformance, durability, serviceabilit, aesthetics, and perceived quality. This study, also, introduced DEA(Data Envelopment Analysis) as an evaluation tool to tackle the problem of how to measure one product against another when each product can be measured along a number of dimensions, and given that there exists no a priori satisfactory weighting scheme to combine these dimensions into an overall rating for each products. In order to a, pp.y the DEA to evaluating the products, we must define two concepts, such as DMU(Decision Making Units) and input-output relationship. Finally, the suggested method in this study was validated through a case study of the electric jar, and this DEA a, pp.oach can be used in evaluating the other products with multi-attrribute quality.