• Smart Structures and Systems
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• v.26 no.4
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• pp.419-433
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• 2020

Investigation of structural integrity has been a critical issue in the field of civil engineering for years. Visual inspection is one of the most available methods to explore deteriorative components in structures. Still, this method is not applicable to invisible damage of structures. Alternatively, system identification methods are capable of tracking modal properties of structures over time. The deviation of these dynamic properties can serve as indicators to access structural integrity. In this study, a modal tracking technique using frequency-domain system identification from seismic responses of structures is proposed. The method first segments the measured signals into overlapped sequential portions and then establishes multiple Hankel matrices. Each Hankel matrix is then converted to the frequency domain, and a temporal-average frequency-domain Hankel matrix can be calculated. This study also proposes the frequency band selection that can divide the frequency-domain Hankel matrix into several portions in accordance with referenced natural frequencies. Once these referenced natural frequencies are unavailable, the first few right singular vectors by the singular value decomposition can offer these references. Finally, the frequency-domain stochastic subspace identification tracks the natural frequencies and mode shapes of structures through quick stabilization diagrams. To evaluate performance of the proposed method, a numerical study is carried out. Moreover, the long-term monitoring strong motion records at a specific site are exploited to assess the tracking performance. As seen in results, the proposed method is capable of tracking modal properties through seismic responses of structures.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.2
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• pp.91-102
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• 2017

Backpack-mounted mapping system is firstly introduced for flexible movement in indoor spaces where satellite-based localization is not available. With the achieved advances in miniaturization and weight reduction, use of LiDAR (Light Detection and Ranging) sensors in mobile platforms has been increasing, and indeed, they have provided high-precision information on indoor environments and their surroundings. Previous research on the development of backpack-mounted mapping systems, has concentrated mostly on the improvement of data processing methods or algorithms, whereas practical system components have been determined empirically. Thus, in the present study, a simulator for a LiDAR sensor (Velodyne VLP-16), was developed for comparison of the effects of diverse conditions on the backpack system and its operation. The simulated data was analyzed by visual inspection and comparison of the data sets' statistics, which differed according to the LiDAR arrangement and moving speed. Also, the data was used as input to a point-cloud registration algorithm, ICP (Iterative Closest Point), to validate its applicability as pre-analysis data. In fact, the results indicated centimeter-level accuracy, thus demonstrating the potentials of simulation data to be utilized as a tool for performance comparison of pointdata processing methods.

• The Korean Journal of Pain
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• v.24 no.2
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• pp.100-104
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• 2011

Background: Myofascial pain syndrome (MPS) is a regional musculoskeletal pain disorder that is caused by myofascial trigger points. The objective of this study was to determine the prevalence of MPS among chronic back pain patients, as well as to identify risk factors and the outcome of this disorder. Methods: This was a prospective observational study involving 126 patients who attended the Pain Management Unit for chronic back pain between 1st January 2009 and 31st December 2009. Data examined included demographic features of patients, duration of back pain, muscle(s) involved, primary diagnosis, treatment modality and response to treatment. Results: The prevalence of MPS among chronic back pain patients was 63.5% (n = 80). Secondary MPS was more common than primary MPS, making up 81.3% of the total MPS. There was an association between female gender and risk of developing MPS ($x^2$ = 5.38, P = 0.02, O.R. = 2.4). Occupation, body mass index and duration of back pain were not significantly associated with MPS occurrence. Repeated measures analysis showed significant changes (P < 0.001) in Visual Analogue Score (VAS) and Modified Oswestry Disability Score (MODS) with standard management during three consecutive visits at six-month intervals. Conclusions: MPS prevalence among chronic back pain patients was significantly high, with female gender being a significant risk factor. With proper diagnosis and expert management, MPS has a favourable outcome.

• Journal of Korean Physical Therapy Science
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• v.12 no.3
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• pp.27-34
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• 2005

The purpose of this study is to find out factors(shoulder level, acromion-occipital length, spine alignment, spine-scapula inferior angle length) of pain of neck & shoulder by 3 Dimensional Moire Scanner. 50 female student s aged 20 to 25 years old participated who lived in Sun-cheon si Jeonnam. They were examined with three measurement methods(Visual Analogue Scale : VAS, Algometer, 3 Dimensional Moire Scanner(IBS-2000). According to the results of multiple regression analysis. 1) There was a significant difference with shoulder level and spine-scapula inferior angle based on VAS. 2) There was a significant difference with shoulder level based of Algometer measurement value in Rhomboid muscles.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.11
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• pp.5530-5546
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• 2016

Automatic analysis and understanding of human activities is a challenging task in computer vision, especially for the surveillance scenarios which typically contains crowds, complex motions and occlusions. To address these issues, a Bag-of-words representation of videos is developed by leveraging information including crowd positions, motion directions and velocities. We infer the crowd activity in a motion field using Category Constrained Correlated Topic Model (CC-CTM) with latent topics. We represent each video by a mixture of learned motion patterns, and predict the associated activity by training a SVM classifier. The experiment dataset we constructed are from Crowd_PETS09 bench dataset and UCF_Crowds dataset, including 2000 documents. Experimental results demonstrate that accuracy reaches 90%, and the proposed approach outperforms the state-of-the-arts by a large margin.

• Journal for History of Mathematics
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• v.27 no.3
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• pp.197-210
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• 2014

Species like insects and fishes have, in many cases, non-overlapping time intervals of one generation and their descendant one. So the population dynamics of such species can be formulated as discrete models. In this paper various discrete population models are introduced in chronological order. The author's investigation starts with the Malthusian model suggested in 1798, and continues through Verhulst model(the discrete logistic model), Ricker model, the Beverton-Holt stock-recruitment model, Shep-herd model, Hassell model and Sigmoid type Beverton-Holt model. We discuss the mathematical and practical significance of each model and analyze its properties. Also the stability properties of stationary solutions of the models are studied analytically and illustratively using GSP, a computer software. The visual outputs generated by GSP are compared with the analytical stability results.

• Journal of KIISE
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• v.43 no.2
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• pp.135-142
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• 2016

Visual analysis of spatiotemporal data has focused on a variety of techniques for analyzing and exploring the data. The goal of these techniques is to explore the spatiotemporal data using time information, discover patterns in the data, and analyze spatiotemporal data. The overall trend flow patterns help users analyze geo-referenced temporal events. However, it is difficult to extract and visualize overall trend flow patterns using data that has no trajectory information for movements. In order to visualize overall trend flow patterns, in this paper, we estimate continuous distributions of discrete events over time using KDE, and we extract vector fields from the continuous distributions using the gravity model. We then apply our technique on twitter data to validate techniques.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.1
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• pp.154-164
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• 2004

The purpose of this theses is to review Hanliu phenomenon, a kind of social and cultural phenomenon, in China around A. D. 2000 in the view of the culture-diffusion theory, and analyze its effect to the fashion style of the new young generation of China. In this theses, Hanliu phenomenon means the enthusiasm of Asian people for Korean mass cultures such as Korean dramas, pop songs and fashions from late 1990's. This research adopts two kinds of methods for analyzing Hanliu phenomenon: a qualitative research method and a quantitative one. As a qualitative research method, we analyzed Hanliu phenomenon with several sources of documentaries and audio-visual materials on it. As a quantitative research method, we conducted a survey of about 100 university students in Beijing for how they feel of korean culture and fashions. The Hanliu phenomenon leads to the popularity of Korean products and the general Korean cultures. Also, it affected the Chinese young generation so much that the Korean fashion becomes popular among them. Its effects to the fashion styles of Chinese youths can be summarized in three factors as follows. Firstly, the fashions of Korean entertainers such as H.O.T hair style and Hip-hop fashion style are widely imitated. Secondly, the preference of Korean fashion products has been widely increased. The number of stores dealing with Korean fashion products has been increased. Finally, Korean culture and products have actively been imitated in China according to the increased popularity of Korean fashion products.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.3
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• pp.229-236
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• 2013

This paper presents the experimental investigation of a biplane micro air vehicle. The effects of geometric parameters, gap, stagger, and decalage angle are investigated at low Reynolds number (~150,000) in a low-speed wind tunnel. A rigid flat plate with an aspect ratio of one and square planform shape is used to evaluate all three geometric parameters. The side dimension of the single flat plate is 0.15 m. The goal is to find an optimal biplane configuration that should exceed monoplane performance by generating high lift and flying as slow as possible, in order to capture high-quality visual recordings. This configuration will directly help to fly at a lower velocity and to make tighter turns that are advantageous in restricted environments. The results show that the aerodynamic performance of the biplane MAV is significantly enhanced through the combination of gap and stagger effects. A performance comparison demonstrates the superiority of the optimal biplane configuration compared to a monoplane in cruise and glide phases. Moreover, no significant compromise is found for the range, endurance, and climb performance.

• Journal of Elementary Mathematics Education in Korea
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• v.14 no.3
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• pp.769-788
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• 2010

This study analyzed the characteristics of units about ratio and rate between Korean mathematics textbooks and MIC of America. With bases to this, I would find the problems and suggested point of curriculums about ratio and rate in order to propose the basic materials of developing mathematic curriculum and textbook and improving the mathematic teaching method. With bases to this, Korean mathematics textbooks should be supplemented as follows. A. Develop the various problems with meaningful situation rather than the problems which can be solved with algorithms and rules. B. Develop the students' rational judgement competence with the situation that can induce the active communication. C. Develop the problem situation that need the student's activity. D. Let the students easily take the situation about ratio and rate with suggesting much visual mode and sustain their interest and positive learning attitude.