• 국제초고층학회논문집
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• 제3권4호
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• pp.305-310
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• 2014

Wind-induced responses of a structure are often evaluated through dynamic analysis, where measured wind forces obtained from a wind-tunnel test and dynamic properties obtained from a FE (Finite Element) model are utilized. However, the FE model generally shows considerable discrepancies in the estimation of natural frequencies compared to field measurements due to some assumptions and simplifications. In this paper, a calibration method that can improve the estimation of natural frequencies in the FE model is proposed, and specific cases are studied for its validity with comparison to the field measurement results.

• Journal of Information Processing Systems
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• 제13권2호
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• pp.305-320
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• 2017

The selection of subset size is of great importance to the accuracy of digital image correlation (DIC). In the traditional DIC, a constant subset size is used for computing the entire image, which overlooks the differences among local speckle patterns of the image. Besides, it is very laborious to find the optimal global subset size of a speckle image. In this paper, a self-adaptive and bidirectional dynamic subset selection (SBDSS) algorithm is proposed to make the subset sizes vary according to their local speckle patterns, which ensures that every subset size is suitable and optimal. The sum of subset intensity variation (${\eta}$) is defined as the assessment criterion to quantify the subset information. Both the threshold and initial guess of subset size in the SBDSS algorithm are self-adaptive to different images. To analyze the performance of the proposed algorithm, both numerical and laboratory experiments were performed. In the numerical experiments, images with different speckle distribution, different deformation and noise were calculated by both the traditional DIC and the proposed algorithm. The results demonstrate that the proposed algorithm achieves higher accuracy than the traditional DIC. Laboratory experiments performed on a substrate also demonstrate that the proposed algorithm is effective in selecting appropriate subset size for each point.

• Earthquakes and Structures
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• 제14권5호
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• pp.389-398
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• 2018

The seismic isolation system makes a structure isolated from ground motions to protect the structure from seismic events. Seismic isolation techniques have been implemented in full-scale buildings and bridges because of their simplicity, economic effectiveness, inherent stability and reliability. As for the responses of an isolated structure due to seismic events, it is well known that the most uncertain aspects are the seismic loading itself and structural properties. Due to the randomness of earthquakes and uncertainty of structures, seismic response distributions of an isolated structure are needed when evaluating the seismic fragility assessment (or probabilistic seismic safety assessment) of an isolated structure. Seismic response time histories are useful and often essential elements in its design or evaluation stage. Thus, a large number of non-linear dynamic analyses should be performed to evaluate the seismic performance of an isolated structure. However, it is a monumental task to gather the design or evaluation information of the isolated structure from too many seismic analyses, which is impractical. In this paper, a new methodology that can evaluate the seismic fragility assessment of an isolated structure is proposed by using stochastic response database, which is a device that can estimate the seismic response distributions of an isolated structure without any seismic response analyses. The seismic fragility assessment of the isolated nuclear power plant is performed using the proposed methodology. The proposed methodology is able to evaluate the seismic performance of isolated structures effectively and reduce the computational efforts tremendously.

• The Journal of Korean Physical Therapy
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• 제22권1호
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• pp.39-45
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• 2010

Purpose: The purpose of this study was to examine changes in functional assessment measures (FAMs) and spatiotemporal gait parameters (STGPs) in healthy older adults before and after a 6-week intervention of a proprioceptive neuromuscular facilitation (PNF) training program. Methods: Thirty healthy older adults (mean age: $73.37{\pm}1.21$ age range: 65-79) were randomly assigned either to an experimental group (participating in a 6-week intervention of PNF training) or a control group (only performing daily activities). Participants in the control group did not receive any training program. Performance was assessed by recording changes in the FAMs and STGPs using functional assessment tools and GAITRite. Results: Participants in the PNF group showed significantly improved functional assessment measures and increased stride length, cadence, velocity, and step width (p<0.05). No significant differences in FAMs and STGPs were found in the control group (p>0.05). Conclusion: Participation in a PNF training program improves FAMs and STGPs, thereby increasing the ability of healthy older adults to maintain dynamic balance during functional performance and gait. These findings support the use of PNF training programs as effective fall-prevention programs for the elderly.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2003년도 추계학술대회 및 정기총회
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• pp.346-349
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• 2003

This paper is intended to assess a system reliability that is changed as time passes. The proposed methodology consists of two steps: (1) predicting probabilities that each component fails at specific time by using a Markov Chain model and (2) calculating reliability of the whole system via Bayesian network. The proposed methodology includes extended Bayesian network model reflecting the case that components are mutually dependent.

• 디지털융복합연구
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• 제14권7호
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• pp.363-371
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• 2016

벤처기업의 기술혁신을 위한 기술력 평가는 급변하는 기업환경, 평가시 사용하는 언어의 모호성과 애매성, 평가지표의 부정확성을 고려해야 한다. 본 논문에서는 벤처기업의 대표적인 정성적 평가요인인 흡수역량 및 기술적 기업가정신을 대상으로 다기준 의사결정법인 Fuzzy-AHP를 적용하여 요인의 중요도와 우선순위 및 동적역량을 산출하는 ACTEM(Absorption Capacity and Technology Entrepreneurship Monitor) 모델을 제안하였다. 평가척도가 되는 요인에 대한 가중치 산출은 퍼지이론을 도입하여 인지적 판단의 애매성을 보완하고, 기존의 기술력 평가 측정에 관한 연구에서 고려하지 않은 흡수역량과 기술적 기업가정신 및 동적역량에 대한 평가 기준들을 제시함으로써, 현실적인 대안을 선택하는 것이 가능하도록 하였다. ACTEM 모델을 기존의 AHP 평가방법과 비교한 결과, 흡수역량에서는 '지식획득', 기술적 기업가 정신에서는 '제품화 능력'이 가장 높게 나오는 등의 타당성을 검증할 수 있었다.

• 대한물리치료과학회지
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• 제17권1_2호
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• pp.1-9
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• 2010

Background: The objective of this study was to determine whether sensorimotor training using an unstable surface affects dynamic balance and gait function in patients with hemiparesis, and to compare the effect of sensorimotor training with that of cycling exercise. Methods: Two subjects with post-stroke hemiparesis volunteered to participate in this study. Single-subject A-B design with alternating treatment was used for this study. Baseline(A) and intervention(B) phases were performed for 7 and 8 sessions, respectively. Sensorimotor training and cycling exercise were performed for 20 minutes in randomized order. Assessment tools were made by using a step test, timed up and go(TUG) test, and 6-minute walk test(6MWT). Results: Each of the participants improved in all three tests after the two interventions. Participants 1 and 2 showed the improvement for their assessment score after sensorimotor training in the step test by 42.1%(p<.05) and 58%, in the TUG, 31% and 19.5%, and in the 6MWT test, 32.3% and 10.6%(p<.05), respectively. After cycling exercise, participants 1 and 2 also improved in the step test by 32.5% and 53.1%, in the TUG, 27.4% and 18%, and in the 6MWT test, 28.8% and 3%. In statistical analysis between the two interventions, sensorimotor training showed a significant increased values in the step test for participant 1 and the 6MWT for participant 2 as compared with those of cycling exercise. Conclusion: Sensorimotor training and cycling exercise are helpful for improving dynamic balance and gait capacity. Furthermore, sensorimotor training may be more helpful than cycling exercise.

• 한국전문물리치료학회지
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• 제25권2호
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• pp.30-43
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• 2018

Background: Hemispatial neglect is defined as the failure to attend, report, respond, or orient toward meaningful stimuli provided in the contralateral side of a brain lesion. Objects: This study was conducted to find out the effect of dynamic trunk equilibirum exercise for stroke patients with hemi-spatial neglect. Methods: This study included 21 stroke subjects, randomly assigned to either the experimental group or the control group. The exercise program consisted of 5 sessions of 20 minutes per week during 4 weeks. The line-bisection test, the Albert test, the balance function score, the Berg balance scale, the postural assessment scale for stroke and the modified Barthel index were measured before and after training. All data were analyzed using SPSS 12.0 for Windows. Between-group and within-group comparison was analyzed by using Independent t-test and Paired t-test respectively. Results: The results of study were as follows: There were significant differences between before and after intervention in both group (p<.05). There were significant differences in the line-bisection test, Albert test, balance function score, Berg balance scale, postural assessment scale for stroke and modified Barthel index between the experimental group and the control group (p<.05). Conclusion: Dynamic trunk equilibrium exercise had a positive effect on patients' neglect, balance ability and activities of daily living. Further studies are required to generalize the results of this study.

• 환경영향평가
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• 제6권2호
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• pp.93-102
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• 1997

Acid rain below pH 5.6 is responsible for 40% of annual precipitation in Korea and it is more serious especially in major cites. Because of that, it is urgent to make measures to reduce the emission of $SO_2$, one of the major air pollutants causing acid rain. The national total emission of $SO_2$ in 1994 was estimated as 1.6 million tons. The $SO_2$ emission in 2020, is expected to increase up to 3.2 million tons, about 2 times that of 1994 under Business-As-Usual scenario. We could take various $SO_2$ reduction measures such as installing desulfurization facilities, the supply of low-sulfur oil and clean fuel(LNG), energy savings, upgrading of production process. However, it is necessary to check the economic feasibility and the attainability to reduction target with a dynamic optimization mode, "Global 2100 Model". The cost-benefit analyses for the measures using the revised "Global 2100 Model" clearly revealed that the desulfurization facilities should be introduced to reduce the $SO_2$ concentration to 0.01 ppm with fuel substitution. If the introduction of desulfurization facilities is delayed, We can not attain the goal of Ministry of Environment before the year of 2012, even in the case that almost all the fuels would be substituted with LNG.

• Smart Structures and Systems
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• 제30권6호
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• pp.557-569
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• 2022

Vibration-based structural health monitoring (SHM) is crucial for the dynamic maintenance of civil building structures to protect property security and the lives of the public. Analyzing these vibrations with modern artificial intelligence and deep learning (DL) methods is a new trend. This paper proposed an unsupervised deep learning method based on a convolutional autoencoder (CAE), which can overcome the limitations of conventional supervised deep learning. With the convolutional core applied to the DL network, the method can extract features self-adaptively and efficiently. The effectiveness of the method in detecting damage is then tested using a benchmark model. Thereafter, this method is used to detect damage and instant disaster events in a rubber bearing-isolated gymnasium structure. The results indicate that the method enables the CAE network to learn the intact vibrations, so as to distinguish between different damage states of the benchmark model, and the outcome meets the high-dimensional data distribution characteristics visualized by the t-SNE method. Besides, the CAE-based network trained with daily vibrations of the isolating layer in the gymnasium can precisely recover newly collected vibration and detect the occurrence of the ground motion. The proposed method is effective at identifying nonlinear variations in the dynamic responses and has the potential to be used for structural condition assessment and safety warning.