• Earthquakes and Structures
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• v.15 no.5
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• pp.487-498
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• 2018

Buckling-restrained braces are passive control devices with high level of energy dissipation ability. However, they suffer from low post-yield stiffness which makes them vulnerable to severe ground motions, especially near-field earthquakes. Among the several methods proposed to improve resistance of BRB frames, mega-brace configuration can be a solution to increase frame lateral strength and stiffness and improve distribution of forces to prevent large displacement in braces. Due to the limited number of research regarding the performance of such systems, the current paper aims to assess seismic performance of BRB frames with mega-bracing arrangement under near-field earthquakes via a detailed probabilistic framework. For this purpose, a group of multi-story mega-BRB frames were modelled by OpenSEES software platform. In the first part of the paper, simplified procedures including nonlinear pushover and Incremental Dynamic Analysis were conducted for performance evaluation. Two groups of near-fault seismic ground motions (Non-pulse and Pulse-like records) were considered for analyses to take into account the effects of record-to-record uncertainties, as well as forward directivity on the results. In the second part, seismic reliability analyses are conducted in the context of performance based earthquake engineering. Two widely-known EDP-based and IM-based probabilistic frameworks are employed to estimate collapse potential of the structures. Results show that all the structures can successfully tolerate near-field earthquakes with a high level of confidence level. Therefore, mega-bracing configuration can be an effective alternative to conventional BRB bracing to withstand near-field earthquakes.

• Structural Engineering and Mechanics
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• v.16 no.1
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• pp.17-34
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• 2003

This paper presents a damage assessment procedure applied to periodic spring mass systems using an eigenvalue sensitivity-based method. The damage is directly related to the stiffness reduction of the damage element. The natural frequencies of periodic structures with one single disorder are found by adopting the transfer matrix approach, consequently, the first order approximation of the natural frequencies with respect to the disordered stiffness in different elements is used to form the sensitivity matrix. The analysis shows that the sensitivity of natural frequencies to damage in different locations depends only on the mode number and the location of damage. The stiffness changes due to damage can be identified by solving a set of underdetermined equations based on the sensitivity matrix. The issues associated with many possible damage locations in large structural systems are addressed, and a means of improving the computational efficiency of damage detection while maintaining the accuracy for large periodic structures with limited available measured natural frequencies, is also introduced in this paper. The incomplete measurements and the effect of random error in terms of measurement noise in the natural frequencies are considered. Numerical results of a periodic spring-mass system of 20 degrees of freedom illustrate that the proposed method is simple and robust in locating single or multiple damages in a large periodic structure with a high computational efficiency.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.5
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• pp.45-53
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• 2011

This paper presents a novel random sampling method for generation adequacy assessment including wind-power. Although a time sequential sampling has advantages than a random sampling in its assessment results, it takes long assessment time. Therefore, an effective random sampling method for generation adequacy assessment is highly recommended to get specific reliability indices quickly. The proposed method is based on the Monte-Carlo simulation with state sampling and it can be applied to generation adequacy assessment with other intermittent power sources.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1247-1252
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• 2004

A objective quality assessment for the evaluation performance of a video transmission system as a basic step for construction of digital video transmission system between the spots and headquarter. Due to a limit of an analog video transmission system and the developments of various digital media and digital video standards, the need of introduce of a digital system are increased gradual1y, At this points. previously performance evaluations are performed and the quality assessment is the most important thing. We can be divided quality assessment method by the subjective quality assessment and objective quality assessment. The subjective quality assessment method has some problems which are required high cost and much time to evaluate the quality, And because existing objective quality assessment method such that PSNR are based on an analog form, the correlation with subjective data is very low. Therefore we design a new objective quality assessment method using Gabor wavelet transform reflecting HVS(Human Visual System), Designed objective quality assessment method is superior to other objective method such that PSNR or EPSNR In this paper, we proposed objective quality assessment using Gabor wavelet can be used for performance evaluation and verification of video transmission system.

• Steel and Composite Structures
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• v.43 no.4
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• pp.465-481
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• 2022

This paper presents a comprehensive integrity assessment of welded structural components, including uniform high- and low-cycle fatigue assessment of welded plate joints and fatigue-induced fracture assessment of welded plate joints. This study reports a series of fatigue and fracture tests of welded plate joints under three-point bending. To unify the assessment protocol for high- and low-cycle fatigue of welded plate joints, this study develops a numerical damage assessment framework for both high- and low-cycle fatigue. The calibrated damage material parameters are validated through the smooth coupon specimens. The proposed damage-based fatigue assessment approach describes, with reasonable accuracy, the total fatigue life of welded plate joints under high- and low-cycle fatigue actions. Subsequently, the study performs a tearing assessment on the ductile crack extension of the fatigue-induced crack. The tearing assessment diagram derives from the load-deformation curve of a single-edge notched bend, SE(B) specimen and successfully predicts the load-crack extension relation for the reported welded plate joints during the stable tearing process.

• Journal of Internet Computing and Services
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• v.17 no.1
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• pp.73-81
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• 2016

This paper deals with the practical experience and lessons to develop a method of course-embedded assessment for program outcomes in Computer Science & Information Engineering. In engineering education, ABEEK(Accreditation Board for Engineering Education of Korea) has been nominated as an official accreditation from Korean government under some conditions of fulfillment. One of the conditions is enforcement of course-embedded assessment for program outcomes. In this paper, a method of course-embedded assessment in Computer Science & Information Engineering is suggested. The case study was done in a basic project course which includes the special assessment methods in project courses. The case study of course-embedded assessment in a basic project course was given with consideration for each step, that is, set up of program outcomes which are highly related to the course, selection of assessment tools such as written examination and project-based assessment, set up of assessment criteria, implementation of course-embedded assessment, and analysis of results. The proposed method is expected to be a good example to construct the whole strategy for course-embedded assessment in Computer Science & Information Engineering.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.7
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• pp.968-975
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• 2014

This paper proposed a evaluation method for individual's subjective preferred location using EEG and emotional assessment. Visual stimulus were sequentially presented a total six points(the top and the bottom of the left, the top and the bottom of the center and the top and the bottom of the right on the screen). EEG were measured from twenty subjects according to each six points. At the same time, we were executed evaluation of subjects preferred location from emotional assessment. Alpha and beta wave were measured in Fp1, Fp2, F7 and F8 location, followed by ten to twenty electrode system. Correlations and variations of alpha and beta wave from each channel were calculated and analyzed. Because of the number of subjects population under 30, we used Speareman test for a correlation analysis between alpha and beta wave. Also, emotional assessments which compose of visual sense harmony, visual sense stability, stability of position and the visibility were performed and were analyzed by average and frequency. After visual stimulus, emotional assessments were performed. From the variance analysis of EEG, beta wave from F7 was appeared statistically significant as significance probability of 0.006. Also, between alpha wave and beta wave appeared a negative correlation(r=-0.190). From the post-hoc test of F7 beta wave, location 1, 5 and 6 appeared to difference statistically significant. Emotional assessment result according to six positions showed 0.00 significance probability. Thus, location and emotional assessment appeared to influence on each other. From the average and frequency analysis of emotional assessment, location 2 showed obtained of best emotional assessment score and appeared lower beta wave than other locations. Finally, most subjects showed a preference for location 2. Through obtained results in this paper, will be helpful to about human emotional assessment and EEG research.

• Corrosion Science and Technology
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• v.11 no.2
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• pp.43-47
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• 2012

Recently, regulatory bodies quite often encourage to adopt risk-based inspection (RBI) and management programs because they can enhance safety simultaneously with deregulation in Korea. RBI is an integrated methodology that factors risk into inspection and maintenance decision making. This paper describes an example of how to use known risk assessment codes (API 580, API 581 BRD) to address such safety analysis requirements for risk management in the refining industry. Specifically, this paper reports the methodology and the results of implementation to the Crude Distillation Unit(CDU) plant of refinery units using the $KGS-RBI^{TM}$ program, developed by the Korea Gas Safety Corporation in reference of API Codes and ASME PC (Post Construction) with a suitable consideration of Korean situation. The results of the risk and reliability assessment using $KGS-RBI^{TM}$ program are useful in determining whether the detected defects are tolerable or required to be repaired. The subsequent decisions are to manage the future inspection, repair and maintenance planning in the risk reduction control.

• Journal of Practical Engineering Education
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• v.10 no.1
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• pp.57-62
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• 2018

The recognition of the importance of lifelong vocational competency development, the proliferation of MOOC, and interest in online education have increased. As a result, efforts are continuously being made to develop an education system for lifelong vocational competency development. However, research on design and development of competency-based evaluation tools and systems in the field of technology engineering is still insufficient. In this paper, we designed and implemented a Competency-based Assessment System for Lifelong Vocational Competency Development(CBAS-LVCD). CBAS-LVCD utilizes NCS-based rubric-based assessment tools to evaluate learners and provides simulation tools for use in technology engineering. This is expected to be of great help in assessing the competencies required for practical affairs in the field of technology engineering, where practical work and on-line testing are limited.

• Journal of Korean Society for Quality Management
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• v.41 no.4
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• pp.623-635
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• 2013

Purpose: The recent major recalls of hazardous products caused consumer product safety acts to be strengthen worldwide. Although the recall system of hazardous products in Korea has been operating based on Framework Act on Product Safety since 2011, the evaluation of product risk has been relied on not the results of objective incident data but the results of illegal product investigations. The purpose of this paper is to propose a product risk assessment model for Korea using injury data. Methods: The authors derived Korea's risk assessment method by analysing the advantages and disadvantages of the most widely used models in advanced countries such as EU's RAPEX RAG and Janpan's R-MAP. In this study, the level of relative frequency and severity of injury are determined based on the objective incident data and the length of hospitalization respectively. In addition, the injury data occurred during 2011 is applied to the proposed risk assessment model for case study. Results: The data analysed in this paper can be classified as high risk, medium risk, low risk, acceptable risk, and safe products through the matrix f rom the combination of the relative frequency and the severity derived. Conclusion: The proposed risk assessment model in this study has advantage obtaining reliable objective results because it uses actual injury data and redeems the drawbacks of the existing models used in advanced countries. Furthermore, because the proposed model shows the high risk products among many, it is expected to be useful especially for customs whose main job is inspecting the imported goods and the government when selecting the target product groups for safety investigation.