• Structural Engineering and Mechanics
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• v.41 no.6
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• pp.791-803
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• 2012

Significant structural damages due to pounding between adjacent superstructures of multi-span reinforced concrete (RC) highway bridges have been observed in past earthquakes. Different methods have been proposed in the literature to mitigate the adverse seismic pounding effects. This paper presents an analytical investigation on the use of magnetorheological (MR) dampers in reducing seismic pounding effects of base-isolated multi-span RC highway bridges. It has been observed that MR damper can effectively reduce the seismic pounding effect. Three control strategies (passive off, passive on, and bang bang control) of MR damper have been investigated. Although all the control strategies are found to be effective, bang bang control has been observed to be the most effective.

• Korean Journal of Adult Nursing
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• v.21 no.6
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• pp.639-651
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• 2009

Purpose: This study examined relationships among stress, stress coping strategies, and somatization in mothers-in-law from multi-cultural families in a rural area. Methods: Elderly mothers-in-law (n=227) living with foreign daughters-in-law completed a self-reporting questionnaire. Data were collected from April to August 2009. Questions related to stress (Visual Analog Scale, VAS), coping strategies (Coping Strategy Scale) for stress, and somatization (Symptom Check List 90, Revised). SPSS/WIN 12.0 program was used for descriptive analysis, t-test, one-way ANOVA, Pearson correlation, and multiple regression analyses. Results: Subjects had a moderate level of stress (5.03). There were significant differences in stress level according to age, educational level, religion, chronic disease, health status, number of children, agreement of an international marriage of her sons, satisfaction in living with a foreign daughter-in-law, and family conflict. Stress showed a significant positive correlation with offensive coping strategy, passive strategy, and somatization. Stress, offensive coping strategy, and passive coping strategy affected the level of somatization. Conclusion: In a family situation involving co-habitation of mother- and foreign daughter-in-law, increased stress experienced by the mother-in-law can lead to increased offensive and passive coping strategies, and increased somatization. More effective means of stress reduction are needed for mothers-in-law from multi-cultural families.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.2
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• pp.153-163
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• 2011

Energy efficiency and indoor air quality have become main issue to develop healthy and sustainable building in these days. As an effort to reduce the energy consumption in multi-residential building, many attempts as like passive design strategies and renewable energy as well as active control method are tried. However, underground parking lot in multi-residential building seldom adopt the sustainable strategies and only mechanical system is installed as usual. Moreover, the mechanical system installed in underground parking lot is rarely operated due to the electric demand for operation after completion. In this study, as an energy efficient measure, natural ventilation system using stack effect as a driving force for underground parking lot will be proposed and the performance of the suggested system will be analyzed by simulation method.

• Journal of the Korean Society of Safety
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• v.38 no.3
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• pp.102-109
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• 2023

Following the accident at Fukushima, the true impact of multi-unit accidents came to light. Accordingly, research related to multi-unit accident effect analysis, risk evaluation, and accident prevention/prevention technology has been conducted. Specific examples are mobile/fixed equipment such as multi-barrier accident coping strategy (MACST) and diverse and flexible coping strategies (FLEX), which have been introduced and installed in multi-units for preventing and mitigating multi-unit accidents. These strategies are useful for enhancing the safety of nuclear power plants (NPPs); however, a more efficient strategy is required in terms of the costs of physical and human resources. To effectively and efficiently mitigate an increase in multi-unit accidents, it is necessary to not only to utilize mobile/fixed equipment but to also use crosstie options with resources that already exist at NPPs. Therefore, we analyzed the current international and domestic status of crosstie systems technology and propose a method to evaluate feasibility alongside risk based on a multi-unit probabilistic safety assessment (PSA). To analyze the international and domestic status of crosstie systems technology, actual cases and related research were studied, and a list of potential crosstie safety resources was derived. Additionally, a case study was performed on crosstie cases of two systems within the assumed six units on-site under a multi-unit accident, and a multi-unit PSA-based risk evaluation method is proposed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.6
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• pp.579-589
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• 2004

The radar signals are generally very sensitive to relative orientations between radar and target. Thus, the performance of a target recognition system significantly deteriorates as the region of aspect angles becomes broader. To address this difficulty, in this paper, we propose a method based on the multi-aspect information in order to improve the classification capability ever for a wide angular region. First, range profiles are used to extract feature vectors based on the central moments and principal component analysis(PCA). Then, a classifier with the use of multi-aspect information is applied to them, yielding an additional improvement of target recognition capability. There are two different strategies among the classifiers that can fuse the information from multi-aspect radar signals: independent methodology and dependent methodology. In this study, the performances of the two strategies are compared within the frame work of target recognition. The radar cross section(RCS) data of six aircraft models measured at compact range of Pohang University of Science and Technology are used to demonstrate and compare the performances of the two strategies.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.1
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• pp.117-135
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• 2016

Performance enhancement is one of the most important issues in high performance distributed computing systems. In such computing systems, online users submit their jobs anytime and anywhere to a set of dynamic resources. Jobs arrival and processes execution times are stochastic. The performance of a distributed computing system can be improved by using an effective load balancing strategy to redistribute the user tasks among computing resources for efficient utilization. This paper presents a multi-class load balancing strategy that balances different classes of user tasks on multiple heterogeneous computing nodes to minimize the per-class mean response time. For a wide range of system parameters, the performance of the proposed multi-class load balancing strategy is compared with that of the random distribution load balancing, and uniform distribution load balancing strategies using simulation. The results show that, the proposed strategy outperforms the other two studied strategies in terms of average task response time, and average computing nodes utilization.

• International Journal of Aeronautical and Space Sciences
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• v.11 no.4
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• pp.285-302
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• 2010

Active aeroelastic control is an emerging technology aimed at providing solutions to structural systems that under the action of aerodynamic loads are prone to instability and catastrophic failures, and to oscillations that can yield structural failure by fatigue. The purpose of the aeroelastic control among others is to alleviate and even suppress the vibrations appearing in the flight vehicle subcritical flight regimes, to expand its flight envelope by increasing the flutter speed, and to enhance the post-flutter behavior usually characterized by the presence of limit cycle oscillations. Recently adaptive and robust control strategies have demonstrated their superiority to classical feedback strategies. This review paper discusses the latest development on the topic by the authors. First, the available control techniques with focus on adaptive control schemes are reviewed, then the attention is focused on the advanced single-input and multi-input multi-output adaptive feedback control strategies developed for lifting surfaces operating at subsonic and supersonic flight speeds. A number of concepts involving various adaptive control methodologies, as well as results obtained with such controls are presented. Emphasis is placed on theoretical and numerical results obtained with the various control strategies.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.5
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• pp.15-24
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• 2008

For high-dimensional classification tasks, such as face recognition, the number of samples is smaller than the dimensionality of the samples. In such cases, a problem encountered in linear discriminant analysis-based methods for dimension reduction is what is known as the small sample size (SSS) problem. Recently, to solve the SSS problem, a way of employing a dissimilarity-based classification(DBC) has been investigated. In DBC, an object is represented based on the dissimilarity measures among representatives extracted from training samples instead of the feature vector itself. In this paper, we propose a new method of optimizing DBCs using multi-level fusion strategies(MFS), in which fusion strategies are employed to represent features as well as to design classifiers. Our experimental results for benchmark face databases demonstrate that the proposed scheme achieves further improved classification accuracies.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.25 no.3
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• pp.89-100
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• 2017

In order for the international aviation community to efficiently and safely manage the gradual increase of air passenger demand, direction suggestions of airport traffic prediction based on future airport capacity requirements, airport design and infrastructure establishment is utilized by airport traffic data that is m comparable internationally. It is a global trend to pursue more efficient airport operating system structure to accept air passenger demand through more realistic comparable data in order to escape from the structure of reckless airport establishment and infrastructure composition based on passenger demand predictions referring to simple statistical data that has existed in the past. This study aimed to seek effective operational measures for the New Jeju airport scheduled to be opened in 2025 by time-series analysis. This study also analysed airport operation strategies, air traffic distribution strategies, cargo volume increase rates and its effectiveness of airports adopting the multi-airport system that have similar operational practices and geographical conditions. This study sought the most appropriate multi airport system application measures for New Jeju airport to promote efficiency and international competitiveness.

• Journal of the Korean School Mathematics Society
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• v.21 no.4
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• pp.419-443
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• 2018

The purpose of this study was to analyze the problem solving strategies of ordinary students, gifted students, pre-service teachers, and in-service teachers with the 'chicken and pig problem,' which has multiple strategies to obtain the solution. For this study, 98 students in the 6th grade elementary schools, 96 gifted students in a gifted institution, 72 pre-service teachers, and 60 in-service teachers were selected. The researcher presented the "chicken and pig" problem and requested them the solution strategies as many as possible for 30 minutes in a free atmosphere. As a result of the study, the gifted students used relatively various and efficient strategies compared to the ordinary students, and there was a difference in the most used strategies among the groups. In addition, the percentage of respondents who suggested four or more strategies was 1% for the ordinary students, 54% for the gifted students, 42% for the pre-service teachers, and 43% for the in-service teachers. As suggestions, the researcher asserted that various kinds of high-quality mathematical problems and solving experiences should be provided to students and teachers and have students develop multi-strategy problems. As a follow-up study, the researcher suggested that multi-strategy mathematical problems should be applied to classroom teaching in a collaborative learning environment and reflected them in teacher training program.