• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.10c
• /
• pp.217-222
• /
• 1998

In these days, mostof marine structures are constructed by reinforcement concrete due to economic reason. Theoretically, it is widely recognized that rebar in sound concrete is safe against corrosion because of the high alkalinity of concrete. However, corrosion for reinforcement concrete made by marine aggregate and exposed to ocean enviroments has become serious social problem. Especially in Korea, with the rapid economic growth construction activities have been accelerated and needed more natural aggregate. Therefore, inevitably marine aggregate had to be used due to limitation of good quality aggregate. In this study, as a part of efforts to establish the fundamental counterplan on corrosion problems related to marine aggregate, concrete specimens with chloride containing material and inhibitor have been studied. And, in order to analyze corrosion characteristics several electrochemical techniques including half-cell potential survery, linear and cyclic polarization tests were carried out.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.27 no.5
• /
• pp.322-327
• /
• 2014

Internal corrosion of the distribution line can be detected in order to develop techniques of non-destructive inspection methods that operate only on the metal track eddy current diagnosis is possible by applying the technique investigated. Sensor for the production of a finite element method modeled by using an eddy current sensor, a distribution line by using an accelerated aging samples of sodium hydroxide was prepared. Sheathed cables for internal corrosion studies detected using an eddy current sensor is considered to be possible.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.6 no.1
• /
• pp.73-79
• /
• 1998

For the design and development of the wheel type excavator, the dynamic effects of travelling on the performance of the equipment should be first analyzed and conside- red in the initial design stage. In order to test the durability of the equipment in a short period, th travelling test should be performed over accelerated durability test tracks. which is more severe than general field roads such as city road, paved road, unpaved road and rough road. In this paper, a parametric study is performed in order to determine important design parameters of durability test track of a wheel type excavator. A rigid body model is developed using DADS and dynamic analysis is performed for the equipment travelling over several test roads with different severity. A comparison of test and analysis results is also presented.

• Computers and Concrete
• /
• v.18 no.3
• /
• pp.421-439
• /
• 2016

Corrosion of embedded reinforcing bars is recognized as being the major cause of deterioration of reinforced concrete structures. With regard to maintenance strategies of concrete nuclear structures, the monitoring of cracking remains of primary importance. Recently, authors have developed a post-treatment technique to extract crack features from continuous computations. In this paper, such technique is applied to carry out a numerical analysis of an accelerated corrosion test. Obtained results allow highlighting specific propagation and failure mechanisms that characterize corrosion-induced cracking.

• Proceedings of the KWS Conference
• /
• 2002.10a
• /
• pp.732-736
• /
• 2002

The introduction of newly developed intelligent and user-friendly robotics has opened a new era in shipbuilding. Together with traditional and low-cost mechanization a record level of welding automation rate has been achieved in the construction of cruise vessels. In the paper modem applications and recent developments of welding automation and robotics in shipbuilding have been described and some forecast for the future trends are given. Development in the field of shipyards will be continued with accelerated speed and we shall have interesting prospects for the near future. New laser techniques can boost the shipyards in a revolutional way when production is rapidly changing, materials will be lighter and quality demands are becoming more strict.

• Structural Engineering and Mechanics
• /
• v.48 no.2
• /
• pp.221-239
• /
• 2013

This paper focuses on a development of strut-and-tie model (STM) to predict the capacity of an improved longitudinal joint for decked bulb-tee bridge systems. Nine reinforced concrete beam/slab specimens anchored by spliced headed bars with different details were tested. Test results were evaluated and compared with an anticipation of the validated STM. The proposed STM provides a lower bound of the ultimate capacity of the joint zone. It shows that the lap length of headed bars has a significant effect on structural behaviors of the improved joint. To develop a full strength joint, the range of the lap length can be determined by the strength and compatibility requirement. Design recommendations to spliced headed bars, concrete strength, as well as lacer bars in the joint zone are proposed for developing a full strength joint.

• Proceedings of the Korean Reliability Society Conference
• /
• 2002.06a
• /
• pp.115-115
• /
• 2002

최근 중장비용 도료의 외관 즉 색상 및 광택의 변화는 상품가치를 결정하는 중요한 요소의 하나로 대두되고 있다. 이와 관련 도장 품질향상을 위해서 각종의 신도료가 개발되고 있고 물성 확인은 필수적이다. 특히 검사 항목중 내후성 확인은 Field에서 2년 이상 장시간의 시험기간이 필요하나 검증기간 단축을 위해 시험실에서 Weathering test를 시행하고 있다. 그러나 이러한 Lab. test 결과와 실제 Field data와의 상관관계를 알 수 없어 추정에 그치는 것이 현실이었다. 본 연구에서는 중장비용 우레탄도료의 내후성에 영향을 미치는 인자를 고려, 물성을 대폭 향상시킨 도료에 대해 시험실 Weathering test 결과와 옥외폭로시험 결과, 실제 장비에 적용한 Data를 토대로 중장비용 우레탄 도료의 내후성시험 가속계수를 도출하여 개발도료의 내후성 검증기간을 단축하고자 하였다.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.04a
• /
• pp.694-699
• /
• 2000

Recently, the degradation of reinforced concrete structures due to physical and chemical attack has been a major issue in construction engineering. One of the main causes of degradation of concrete structures can be ascribed to chloride-induced corrosion, i.e., the rapid penetration of chloride ions into concrete. To estimate durability of reinforced concrete structures exposed to marine environment, many different kinds of accelerated tests to evaluate the concrete diffusivity were proposed. In this study, present test methods are reviewed and a proper test method for concrete is selected. The diffusion coefficients of concrete with corrosion inhibitor are measured using the proposed method, and then, measured values are compared to those of concrete without corrosion inhibitor. It is found from experimental results that diffusion coefficient re decreased with curing ages.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1997.10a
• /
• pp.307-312
• /
• 1997

The sea water resistance of cement and concrete must be compared when it used for construction in the ocean. The sea water resistance of the concrete specimens using three types of cements such as ordinary Portland cement, sulfate resistance Portland cement, blastfurnace slag cement were studied. In this study, an accelerated test for access sea water resistance by subjecting the concrete specimens to repeated cycles of concentrated sea water immersion and hot wind drying was employed. This study proved that sulfate resistance Portland cement had higher resistance for sea water.

• Steel and Composite Structures
• /
• v.25 no.5
• /
• pp.523-534
• /
• 2017

Cable-supported ribbed beam composite slab structure (CBS) is proposed in this study. As a new cable-supported structure, it has many merits such as long span availability and cost-saving. Inspired by the previous research on cable-supported structures, the fabrication and construction process are developed. Pre-stress design method based on static equilibrium analysis is presented. In the algorithm, the iteration convergence can be accelerated and the calculation result can be kept in an acceptable precision by setting a rational threshold value. The accuracy of this method is also verified by experimental study on a 1:5 scaled model. Further, important parameters affecting the mechanical features of the CBS are discussed. The results indicate that the increases of sag-span ratio, depth of the ribbed beam and cable diameter can improve the mechanical behavior of the CBS by some extent, but the influence of strut sections on mechanical behavior of the CBS is negligible.