• Title/Summary/Keyword: High-dimensional data

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Three-dimensional human activity recognition by forming a movement polygon using posture skeletal data from depth sensor

  • Vishwakarma, Dinesh Kumar;Jain, Konark
    • ETRI Journal
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    • v.44 no.2
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    • pp.286-299
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    • 2022
  • Human activity recognition in real time is a challenging task. Recently, a plethora of studies has been proposed using deep learning architectures. The implementation of these architectures requires the high computing power of the machine and a massive database. However, handcrafted features-based machine learning models need less computing power and very accurate where features are effectively extracted. In this study, we propose a handcrafted model based on three-dimensional sequential skeleton data. The human body skeleton movement over a frame is computed through joint positions in a frame. The joints of these skeletal frames are projected into two-dimensional space, forming a "movement polygon." These polygons are further transformed into a one-dimensional space by computing amplitudes at different angles from the centroid of polygons. The feature vector is formed by the sampling of these amplitudes at different angles. The performance of the algorithm is evaluated using a support vector machine on four public datasets: MSR Action3D, Berkeley MHAD, TST Fall Detection, and NTU-RGB+D, and the highest accuracies achieved on these datasets are 94.13%, 93.34%, 95.7%, and 86.8%, respectively. These accuracies are compared with similar state-of-the-art and show superior performance.

Classification of Elderly Women's Foot Type (노년 여성의 발 유형분류)

  • Kim, Nam-Soon;Do, Wol-Hee
    • Journal of the Korean Society of Clothing and Textiles
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    • v.38 no.3
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    • pp.305-320
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    • 2014
  • This study identifies the foot shapes of elderly women by classifying foot type according to the 3D shape of the foot and 2D sole type analyzing individual characteristics. The subjects were 295 elderly women over 60 years of age who live in Gwangju. A foot scanner (K&I Technology $Nexcan^{(R)}$) was used to obtain three-dimensional shapes of feet and a flat bad scanner (HP Scanjet G2410) was used to obtain the two-dimensional shapes of soles. The anthropometric measuring items consisted of 59 items estimated on the right foot of each subject. Data were analyzed by various statistical methods such as factor analysis, ANOVA and cluster analysis using the SPSS 19.0 statistical program. To classify the side type of elderly women's feet, three-dimensional measurement data were analyzed for the 27 measurement items using factor analysis and 6 factors were extracted (inside height and side gradient, ankle thickness, toe height and midfoot size, lateral malleolus height, instep, and heel height and gradient). A cluster analysis resulted in three types: 36.5% belonged to Type 1 (high forefoot and high midfoot), 31.1% belonged to Type 2 (high forefoot and low midfoot), and 32.4% belonged to Type 3 (low forefoot and high midfoot). The distribution was relatively even. For the sole, 8 factors were extracted (ball width and medial foot protrusion, lateral foot protrusion, forefoot and hindfoot length ratio, ball gradient, heel size, toe breadth, lateral ball length, and foot length) and a cluster analysis resulted in three Types (Type H, Type D, and Type A). The largest proportion (42.7%) belonged to Type H, which is the same as the elderly men's case.

Quantitative Analysis for Surface Recession of Ablative Materials Using High-speed Camera and 3D Profilometer (초고속 카메라와 삼차원 표면 측정기를 이용한 삭마 재료의 정량적 표면 침식 분석)

  • Choi, Hwa Yeong;Roh, Kyung Uk;Cheon, Jae Hee;Shin, Eui Sup
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.9
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    • pp.735-741
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    • 2018
  • In this paper, the surface recession of ablative materials was quantitatively analyzed using a high-speed camera and a three-dimensional profilometer. The ablation tests of the graphite and carbon/phenolic composite samples were performed using a 0.4 MW arc-heated wind tunnel for simulating the atmospheric re-entry environment. The real-time images during the ablation test were captured by the high-speed camera, and analyzed to calculate the surface recession and recession rate. Also, the surface data of samples were obtained using a three-dimensional profilometer, and the surface recession was precisely calculated from the difference of height between the surface data before and after the test. It is effective to complement the two measurement results in the comprehensive analysis of surface recession phenomena.

An Efficient Bulk Loading for High Dimensional Index Structures (고차원 색인 구조를 위한 효율적인 벌크 로딩)

  • Bok, Kyoung-Soo;Lee, Seok-Hee;Cho, Ki-Hyung;Yoo, Jae-Soo
    • The Transactions of the Korea Information Processing Society
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    • v.7 no.8
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    • pp.2327-2340
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    • 2000
  • Existing bulk loading algorithms for multi-dimensional index structures suffer from satisfying both index construction time and retrieval perfonnancc. In this paper, we propose an efficient bulk loading algorithm to construct high dimensional index structures for large data set that overcomes the problem. Although several bulk loading algorithms have been proposed for this purpose, none of them improve both constnlCtion time and search performance. To improve the construction time, we don't sort whole data set and use bisectiou algorithm that divides the whole data set or a subset into two partitions according to the specific pivot value. Also, we improve the search performance by selecting split positions according to the distribution properties of the data set. We show that the proposed algorithm is superior to existing algorithms in terms of construction time and search perfomlance through various experiments.

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Label Embedding for Improving Classification Accuracy UsingAutoEncoderwithSkip-Connections (다중 레이블 분류의 정확도 향상을 위한 스킵 연결 오토인코더 기반 레이블 임베딩 방법론)

  • Kim, Museong;Kim, Namgyu
    • Journal of Intelligence and Information Systems
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    • v.27 no.3
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    • pp.175-197
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    • 2021
  • Recently, with the development of deep learning technology, research on unstructured data analysis is being actively conducted, and it is showing remarkable results in various fields such as classification, summary, and generation. Among various text analysis fields, text classification is the most widely used technology in academia and industry. Text classification includes binary class classification with one label among two classes, multi-class classification with one label among several classes, and multi-label classification with multiple labels among several classes. In particular, multi-label classification requires a different training method from binary class classification and multi-class classification because of the characteristic of having multiple labels. In addition, since the number of labels to be predicted increases as the number of labels and classes increases, there is a limitation in that performance improvement is difficult due to an increase in prediction difficulty. To overcome these limitations, (i) compressing the initially given high-dimensional label space into a low-dimensional latent label space, (ii) after performing training to predict the compressed label, (iii) restoring the predicted label to the high-dimensional original label space, research on label embedding is being actively conducted. Typical label embedding techniques include Principal Label Space Transformation (PLST), Multi-Label Classification via Boolean Matrix Decomposition (MLC-BMaD), and Bayesian Multi-Label Compressed Sensing (BML-CS). However, since these techniques consider only the linear relationship between labels or compress the labels by random transformation, it is difficult to understand the non-linear relationship between labels, so there is a limitation in that it is not possible to create a latent label space sufficiently containing the information of the original label. Recently, there have been increasing attempts to improve performance by applying deep learning technology to label embedding. Label embedding using an autoencoder, a deep learning model that is effective for data compression and restoration, is representative. However, the traditional autoencoder-based label embedding has a limitation in that a large amount of information loss occurs when compressing a high-dimensional label space having a myriad of classes into a low-dimensional latent label space. This can be found in the gradient loss problem that occurs in the backpropagation process of learning. To solve this problem, skip connection was devised, and by adding the input of the layer to the output to prevent gradient loss during backpropagation, efficient learning is possible even when the layer is deep. Skip connection is mainly used for image feature extraction in convolutional neural networks, but studies using skip connection in autoencoder or label embedding process are still lacking. Therefore, in this study, we propose an autoencoder-based label embedding methodology in which skip connections are added to each of the encoder and decoder to form a low-dimensional latent label space that reflects the information of the high-dimensional label space well. In addition, the proposed methodology was applied to actual paper keywords to derive the high-dimensional keyword label space and the low-dimensional latent label space. Using this, we conducted an experiment to predict the compressed keyword vector existing in the latent label space from the paper abstract and to evaluate the multi-label classification by restoring the predicted keyword vector back to the original label space. As a result, the accuracy, precision, recall, and F1 score used as performance indicators showed far superior performance in multi-label classification based on the proposed methodology compared to traditional multi-label classification methods. This can be seen that the low-dimensional latent label space derived through the proposed methodology well reflected the information of the high-dimensional label space, which ultimately led to the improvement of the performance of the multi-label classification itself. In addition, the utility of the proposed methodology was identified by comparing the performance of the proposed methodology according to the domain characteristics and the number of dimensions of the latent label space.

Comparison of the Performance of Clustering Analysis using Data Reduction Techniques to Identify Energy Use Patterns

  • Song, Kwonsik;Park, Moonseo;Lee, Hyun-Soo;Ahn, Joseph
    • International conference on construction engineering and project management
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    • 2015.10a
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    • pp.559-563
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    • 2015
  • Identification of energy use patterns in buildings has a great opportunity for energy saving. To find what energy use patterns exist, clustering analysis has been commonly used such as K-means and hierarchical clustering method. In case of high dimensional data such as energy use time-series, data reduction should be considered to avoid the curse of dimensionality. Principle Component Analysis, Autocorrelation Function, Discrete Fourier Transform and Discrete Wavelet Transform have been widely used to map the original data into the lower dimensional spaces. However, there still remains an ongoing issue since the performance of clustering analysis is dependent on data type, purpose and application. Therefore, we need to understand which data reduction techniques are suitable for energy use management. This research aims find the best clustering method using energy use data obtained from Seoul National University campus. The results of this research show that most experiments with data reduction techniques have a better performance. Also, the results obtained helps facility managers optimally control energy systems such as HVAC to reduce energy use in buildings.

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A Study on the Coling Charaacteristics of a High Precision Machine Tool spindle (고정밀 공작기계 주축계의 냉각특성에 관한 연구)

  • 김수태
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1997.04a
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    • pp.12-17
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    • 1997
  • Unsteady-state temperature distributions and thermal deformations of a high presision spindle are stueied in this paper. Thress dimensional model is built for analysis, and the amount of heat transfer coefficient are estimated. Temperature distributions and thermal deformations of a model are analyzed using the finite element method and the thermal boundary values. Numerical results are compared with the measured data. The results show that the thermal deformations and the temperature distributions of a high precision machine spindle can be reasonably estimated using the three dimensional model and the finite element method, and that the temperature rise by the heat generation of the bearing is effectively lowered by cooling of the shaft and the housing of a machine tool spindle.

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An Analysis of Surface irrigation's Hydraulic Characteristics at a Paddy Field Using a Two-Dimensional Numerical Model (2차원 유한체적 수치모형을 이용한 논의 지표관개 수리특성 분석)

  • Park, Seung-Woo;Park, Jong-Min;Kang, Min-Goo
    • Journal of The Korean Society of Agricultural Engineers
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    • v.46 no.4
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    • pp.3-11
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    • 2004
  • A finite volume model is developed to simulate the surface irrigation at a paddy field. The model's capabilities are validated through comparison with the simulafed results and the observed data obtained by various experimental tests, and the simulated results are in good agreement with the observed pending depth. The result of surface irrigation simulation shows that the longer the paddy field's the length of long-sided becomes, the longer the advance and storage time is taken. To analyze surface irrigation performance with variable inflow rate, three patterns of flow variation-constant rate, initially high then low, and initially low then high-were studied. The results show that at the pattern with initially high followed by low during the latter half of the irrigation the advance time is shortest, but the pending depth of irrigation completion and irrigation effiency are the little difference between irrigation patterns.

Air Quality Impact Analysis for Point Sources Using Three-Dimensional Numerical Models (삼차원 수치모델을 이용한 점오염원의 대기환경영향 평가)

  • 김영성;오현선;김진영;강성대;조규탁;홍지형
    • Journal of Korean Society for Atmospheric Environment
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    • v.17 no.4
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    • pp.331-345
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    • 2001
  • The increase of carbon monoxide in the ambient air due to the emissions from point sources without control was estimated using three -dimensional numerical models. The target area was Ulsan where one of the largest industrial complexes was located. As a typical example using numerical models for air quality impact analysis of criteria pollutants that will determine whether the air quality standards would be exceeded or not, the following approaches were suggested. They include: (1) investigation of pre-existing atmospheric conditions, (2) identification of major factors causing high concentrations, (3) selection of episode days. (4) preparation of three-dimensional meteorological data, (5) confirmation of agreement between measured and predicted concentrations in the emission conditions of episode days, and (6) estimation of the impact due to changes of the emission conditions. In the present work, daily meteorological conditions for the specific period were classified into four clusters of distinctive features, and the episode days were selected individually from each cluster. Emphasis was placed on the selection of episodes representing meteorological conditions conducive to high concentrations especially for point sources that were sensitive to the wind direction variations.

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High-dimensional change point detection using MOSUM-based sparse projection (MOSUM 성근 프로젝션을 이용한 고차원 시계열의 변화점 추정)

  • Kim, Moonjung;Baek, Changryong
    • The Korean Journal of Applied Statistics
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    • v.35 no.1
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    • pp.63-75
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    • 2022
  • This paper proposes the so-called MOSUM-based sparse projection method for change points detection in high-dimensional time series. Our method is inspired by Wang and Samworth (2018), however, our method improves their method in two ways. One is to find change points all at once, so it minimizes sequential error. The other is localized so that more robust to the mean changes offsetting each other. We also propose data-driven threshold selection using block wild bootstrap. A comprehensive simulation study shows that our method performs reasonably well in finite samples. We also illustrate our method to stock prices consisting of S&P 500 index, and found four change points in recent 6 years.