• Proceedings of the Korea Concrete Institute Conference
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• 1992.10a
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• pp.50-53
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• 1992

The damages due to alkali-aggregate reaction between the reactive silicia constituents of the aggregate and the alkalies in cement have been frequently reported since 1923 in America . Recently alkali-aggregate reaction, especially alkali-silica reaction, can be found all over the area using crushed stones. The first research, in 1990, was performed to identify the alkali-silica reactivity of 18 sets of crushed stones used in domestic ready-mixed concrete plant as coarse aggregates by 4 petrollgical, chemical and mortar bar method, And the study was continued with 10 sets of crushed stones in this research. It was found that all the aggregates used in this study are innocuous at alkali-silica reaction.

• Proceedings of the Korea Concrete Institute Conference
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• 1991.04a
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• pp.93-98
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• 1991

The damages due to alkali-aggragate reaction between the reactive silica constituents of the aggregate and the alkalies in cement have been frequently reported since 1923 in America. Recently, alkali-aggregate reaction, especially alkali-silica reaction, can be found all over the area using crushed stones. This research was performed to indentify the alkali-silica reactivity of 18 sets of crushed stones being used currently in domestic reacy-mixed concrete plant as coarse aggregates by petrollogical, chemical and mortar bar method. It is found that all the aggregates used in this study are innocuous at alkali-silica reaction. Further study will be carried out with some aggregates in more severe conditions.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.10a
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• pp.135-142
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• 2004

Two-step identification approach for effective bridge health monitoring is proposed to alleviate the issues associated with many unknown parameters faced in the real structures and to improve the accuracy in the estimate results. It is suitable for on-line monitoring scheme, since the damage assessment is not always needed to be carried out whereas the alarming for damages is to be continuously monitored. In the first step for screening potential damaged members, damage indicator method based on modal strain energy, probabilistic neural networks and the conventional neural networks using grouping technique are used and then the conventional neural network technique is utilized for damage assessment on the screened members in the second step. The proposed methods are verified through a field test on the northern-most span of old Hannam Grand Bridge.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.29-36
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• 2004

In this paper, a study of damage detection for 2-Dimensional Truss Structures using the parametric projection filter theory is presented. Many researchers are interested in inverse problem and one of solution procedures for inverse problems that are very effective is the approach using the filtering algorithm in conjunction with numerical solution methods. In filtering algorithm, the Kalman filtering algorithm is well known and have been applied to many kind of inverse problems. In this paper, the Parametric projection filtering in conjunction with structural analysis is applied to the identification of damages in 2-D truss structures. The natural frequency and modes of damaged truss model are adopted as the measurement data. The effectiveness of proposed method is verified through the numerical examples.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.6
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• pp.545-550
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• 2004

Recent natural disasters like flooding and slope collapse have shown the need for natural risk management system, as they endanger directly public health and cause severe damages on the national economy. In order to improve the efficiency of risk management systems, this management system based on AANN(Auto-Associative Neural Network)is proposed in this paper. AANN can be effectively used for identification of abnormal data and data compression. The proposed AANN-based risk management system collects and stores measurement data from sensors and transmits them to remote server for web-monitoring. Generally, it is desirable to transmit the compressed data instead of raw data in normal state. However, if dangerous situation happens, rapid tramission of measurement data should be required. These requirements are easily satisfied by using AANN. In order to verify the feasibilities of the proposed system, The AANN-based risk management system is applied to slope collapse monitoring system.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.1
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• pp.39-51
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• 2004

Ozone(O$_3$), one of best-known toxic air pollutant, act as a strong oxidant. It is possible that skins exposed to the air can be easily damaged by such oxidative air pollutants. Therefore, in the present study, anti-oxidative effects of natural product. on $O_2$ㆍ and ㆍOH were investigated by EPR. Ozone caused protein damage and lipid oxidation, in HaCaT and B16F10 leading ultimately to programmed cell death. It also reduced the level of antioxidant molecules including ascorbic acid and tocopherol in stratum comeum. However, antioxidants originated from natural products could protect skin from these products could protect skin from these oxidative damages. We concluded that eight natural extracts including Rosa davurica, Ligularia sibrica, Green tea acted as strong antioxidants against ozone.

• Structural Engineering and Mechanics
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• v.64 no.3
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• pp.353-360
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• 2017

This study presents the Big Bang and Big Crunch (BB-BC) optimization algorithm for detection of structure damage in large severity. Local damage is represented by a perturbation in the elemental stiffness parameter of the structural finite element model. A nonlinear objective function is established by minimizing the discrepancies between the measured and calculated acceleration responses (AR) of the structure. The BB-BC algorithm is utilized to solve the objective function, which can localize the damage position and obtain the severity of the damage efficiently. Numerical simulations have been conducted to identify both single and multiple structural damages for beam, plate and European Space Agency Structures. The present approach gives accurate identification results with artificial measurement noise.

• Journal of Mechanical Science and Technology
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• v.17 no.5
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• pp.637-646
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• 2003

In the previous study, the inverse perturbation method was used to identify structural damages. Because all unmeasured DOFs were considered as unknown variables, considerable computational effort was required to obtain reliable results. Thus, in the present study, a system condensation method is used to transform the unmeasured DOFs into the measured DOFs, which eliminates the remaining unmeasured DOFs to improve computational efficiency. However, there may still arise a numerically ill-conditioned problem, if the system condensation is not adequate for numerical Programming or if the system condensation is not recalibrated with respect to the structural changes. This numerical problem is resolved in the present study by adopting more accurate accelerated improved reduced system (AIRS) as well as by updating the transformation matrix at every step. The criterion on the required accuracy of the condensation method is also proposed. Finally, numerical verification results of the present accelerated inverse perturbation method (AIPM) are presented.

• Proceedings of the Korean Society of Toxicology Conference
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• 2001.10a
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• pp.93-94
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• 2001

Former studies dealing with combined effects caused by chemical compounds in the metabolically competent hepatoma cell line Hep G2 indicated that Hep G2 cells are useful and sensitive indicators for the identification of synergisms of promutagens, comutagens and antimutagens which are relevant in eukryontic (human) cells. In the present study we examined the modulation of DNA damages by the suspected antimutagens ascorbic acid, beta-carotene, alpha-naphthoflavone and beta-naphthoflavone in Hep G2 cells.(omitted)

• Journal of the Korea Safety Management & Science
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• v.6 no.3
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• pp.197-209
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• 2004

A company wishes to obtain a competitive edge by adopting an efficient logistics information system to control the logistics management process. The elements of the competitive edges a company targets are to maintain good quality, reduce cost and on-time delivery and those competitive edges are closely related to the cycle time of a product. The logistics information system in a company is also closely tied with other business activities than the logistics itself. Therefore it is essential to choose a system that will help rationalize the logistics but also overall business operations along the supply chain from manufacturing to distribution of the products. This paper aims to research and analyze a problem with a logistics information system through case study and to suggest a logistics information system with RFID in place adopted to eliminate problems such as damages, loss and defect rates.