• Journal of Intelligence and Information Systems
• /
• v.15 no.4
• /
• pp.53-64
• /
• 2009

This paper presents a performance evaluation of shape descriptors for gait analysis in case of silhouette sequence images. We used moment descriptors(MD), Fourier descriptors(FD) and Zernike descriptors(ZD) as a shape descriptor. To evaluate their performance, we firstly defined the performance index, that is, AI(asymmetry index) and PI(periodic index) based on the periodic property of the gait images. This is why they are represented by periodic parameters due to periodic gait images. This index means that how the shape is represented periodically. According to these indexes, we evaluated the data sets with periodic images, downloaded from internet. The results showed that Zernike descriptors had better performance of AI = 1.09 and PI = 2.21 than others. And in case of FD and ZD, it's efficient to implement the gait analysis with 5~10 parameters.

• Korean Journal of Applied Biomechanics
• /
• v.22 no.3
• /
• pp.305-314
• /
• 2012

The purpose of this study was to investigate the effects of joint kinetics and coordination on within-individual differences in maximum vertical jump. 10 male subjects aged 20 to 30 performed six trials in maximum vertical jump and with based on jump height the good(GP) and bad(BP) performances for each subject were compared on joint kinetics of lower extremity and coordination parameters such as joint reverse and relative phase. The results showed that maximum moment, power, and work done of hip joint and maximum moment of ankle joint in GP were significantly higher than that in the BP but no significant differences for the knee joint. We could observe a significant difference in joint reverse timing between both conditions. And also the relative phase on ankle-knee and ankle-hip in GP were significantly lower than that in the BP, which means that in GP joint movements were more in-phase synchronized mode. In conclusion, mechanical outputs of hip and ankle joints had an effect on within-individual differences in vertical jump and the inter-joint coordination and coordination including sequence and timing of joint motion also might be high influential factors on the performances within individual.

• Composites Research
• /
• v.12 no.3
• /
• pp.45-54
• /
• 1999

In this paper, an experimental study on the buckling and postbuckling control of a laminated composite beam with eccentrically embedded SMA wire actuators is performed. For the purpose of enhancing the critical buckling load, buckling control is investigated through the use of reactive moment associated with the shape recovery force of SMA wire actuators. To improve the control authority for the buckling and postbuckling control of the SMA-composite beam, closed-loop control is used. The buckling and postbuckling control behaviours are presented and discussed qualitatively and quantitatively on loaddeflection plots considering the stacking sequence of the laminate, slenderness ratio of the beam and activation conditions of the SMA wire actuators. By maintaining the desired deflection shape with the proper reactive moment, buckling control can be extended to the postbuckling of the SMA-composite beam subjected to an external load.

• Journal of the Korean Mathematical Society
• /
• v.47 no.2
• /
• pp.263-275
• /
• 2010

Let {$X_n;n\;\geq\;1$} be a strictly stationary sequence of negatively associated random variables with mean zero and finite variance. Set $S_n\;=\;{\sum}^n_{k=1}X_k$, $M_n\;=\;max_{k{\leq}n}|S_k|$, $n\;{\geq}\;1$. Suppose $\sigma^2\;=\;EX^2_1+2{\sum}^\infty_{k=2}EX_1X_k$ (0 < $\sigma$ < $\infty$). We prove that for any b > -1/2, if $E|X|^{2+\delta}$(0<$\delta$$\leq$1), then $$lim\limits_{\varepsilon\searrow0}\varepsilon^{2b+1}\sum^{\infty}_{n=1}\frac{(loglogn)^{b-1/2}}{n^{3/2}logn}E\{M_n-\sigma\varepsilon\sqrt{2nloglogn}\}_+=\frac{2^{-1/2-b}{\sigma}E|N|^{2(b+1)}}{(b+1)(2b+1)}\sum^{\infty}_{k=0}\frac{(-1)^k}{(2k+1)^{2(b+1)}}$$ and for any b > -1/2, $$lim\limits_{\varepsilon\nearrow\infty}\varepsilon^{-2(b+1)}\sum^{\infty}_{n=1}\frac{(loglogn)^b}{n^{3/2}logn}E\{\sigma\varepsilon\sqrt{\frac{\pi^2n}{8loglogn}}-M_n\}_+=\frac{\Gamma(b+1/2)}{\sqrt{2}(b+1)}\sum^{\infty}_{k=0}\frac{(-1)^k}{(2k+1)^{2b+2'}}$$, where $\Gamma(\cdot)$ is the Gamma function and N stands for the standard normal random variable.

• Steel and Composite Structures
• /
• v.22 no.5
• /
• pp.1115-1140
• /
• 2016

This paper proposes an extension of the Improved Forced Based Design procedure to 3D steel structures. The Improved Forced Based Design (IFBD) procedure consists of a more rational sequence of the design checks proposed in Eurocode 8 and involves a more realistic selection of the behaviour factor instead of selecting an empirical value based on the ductility class and lateral resisting system adopted. The design procedure was tested on a group of four 3D steel structures, composed by moment-resisting frames with three storeys height and the same plan configuration in all storeys. The plan configuration was defined in order to target lateral restrained or unrestrained systems as well as plan regular or irregular structures. The same group of structures was also designed according to the force-based process prescribed in Eurocode 8. The member sizes obtained through the two approaches were compared and the seismic performance was assessed through nonlinear static and time-history analyses. The limit states referred to structural and non-structural damage, considering the two levels design approach, which are the serviceability and the ultimate limit states, were examined. The results obtained reveal that the IFBD leads to more economical structures that still comply with the performance requirements prescribed in Eurocode 8.

• International Journal of High-Rise Buildings
• /
• v.6 no.1
• /
• pp.1-9
• /
• 2017

The Pertamina Energy Tower (PET) and Manhattan West North Tower (MWNT) are two supertall towers recently designed and engineered by Skidmore, Owings & Merrill (SOM). The structural system for both buildings consists of an interior reinforced concrete core and a perimeter moment frame system, which is primarily structural steel. As is typical for tall towers with both concrete and steel elements, staged construction analysis was performed in order to account for the long term effects of creep and shrinkage, which result in differential shortening between the interior concrete core and steel perimeter frame. The particular design of each tower represents two extremes of behavior; PET has a robust connection between the perimeter and core in the form of three sets of outriggers, while the perimeter columns of MWNT do not reach the ground, but are transferred to the core above the base. This paper will present a comparison of the techniques used during the analysis and construction stages of the design process with the goal of understanding the differences in structural behavior of these two building systems in response to the long term effects of creep and shrinkage. This paper will also discuss the design and construction techniques implemented in order to minimize the differential shortening between the interior and exterior over the lifespan of these towers.

• International Journal of Concrete Structures and Materials
• /
• v.18 no.3E
• /
• pp.173-181
• /
• 2006

The objectives of this study are to evaluate the reliability of an existing nonlinear analysis program for predicting the inelastic behavior of reinforced concrete frame with seismic details and to observe the redistribution of the internal forces, which can not be easily measured by an experiment. In order to carry out this task, the nonlinear analysis program of IDARC 2D(3) was run on a 2-bay, 2-story moment-resisting reinforced concrete plane frame with seismic details. (1) The effort to obtain the results of the analysis similar to those of experiment was made by determining the appropriate values of model parameters. The comparison of the analysis results with those of experiment and the observation of the distribution of internal forces obtained through nonlinear analysis points to the following conclusions. (1) The overall relationship between lateral load and lateral displacement given by the analysis is similar to that of experiment. However, the values of initial stiffness and the amount of energy dissipation in the initial displacement steps given by the analysis show larger values than those of experiment. (2) The analysis provided detailed information on the distribution and redistribution of internal forces and proved useful in elucidating the crack pattern, the sequence of the occurrence of plastic hinges, and the failure or yielding mechanism for the whole structure. (3) In spite of the similarity in overall behavior of analysis and experiment, there exists a significant discrepancy in some local behaviors. Furthermore, the hysteresis in the relationship between moment and curvature in some column ends have shown sudden deteriorations in strength, which can not be interpreted satisfactorily at the present time. Therefore, it is necessary to develop a better analytical model to fill this knowledge gap.

• Nuclear Engineering and Technology
• /
• v.51 no.6
• /
• pp.1616-1625
• /
• 2019

Measuring occurrence times of random events, aimed to determine the statistical properties of the governing stochastic process, is a basic topic in science and engineering, and has been the subject of numerous mathematical modeling approaches. Often, true statistical properties deviate from measured properties due to the so called dead time phenomenon, where for a certain time period following detection, the detection system is not operational. Understanding the dead time effect is especially important in radiation measurements, often characterized by high count rates and a non-reducible detector dead time (originating in the physics of particle detection). The effect of dead time can be interpreted as a suitable rarefied sequence of the original time sequence. This paper provides a limit theorem for a high rate (diffusion-scale) counter with extendable (Type II) dead time, where the underlying counting process is a renewal process with finite second moment for the inter-event distribution. The results are very general, in the sense that they refer to a general inter arrival time and a random dead time with general distribution. Following the theoretical results, we will demonstrate the applicability of the results in three applications: serially connected components, multiplicity counting and measurements of aerosol spatial distribution.

• Structural Engineering and Mechanics
• /
• v.82 no.1
• /
• pp.17-30
• /
• 2022

The use of composite patches for the reduction of stresses at the level of the damaged zone in aeronautical structures has experienced rapid expansion given its advantages over conventional mechanical processes (riveting, bolting, etc.). Initially, The research axes in this field were aimed at choosing suitable mechanical properties for the composite and the adhesive, then to optimize the shape of the composite patch in order to ensure good load transfer and avoid having a debonding at the level of the edges essentially for the case of a repair by single side where the bending moment is present due to the non-symmetry of the structure. Our work falls within this context; the objective is to analyze by the finite element method the fracture behavior of a damaged plate repaired by composite patch. Stress reduction at the edge is accomplished by creating a variable angle chamfer on the composite patch. The effects of the crack length, the laminate sequence and the nature of the patch as well as the use of a hybrid patch were investigated. The results show clearly that a beveled patch reduces the stress concentrations in the damaged area and even at its edges. The hybrid patch also ensures good durability of the repair by optimizing its stacking sequence and the location of the different layers according to the fibers orientations.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.47 no.1
• /
• pp.92-103
• /
• 2010

In this paper, a method for the recognition of dynamic hand gestures in various backgrounds using Dynamic Space Time Warping(DSTW) algorithm is proposed. The existing method using DSTW algorithm compares multiple candidate hand regions detected from every frame of the query sequence with the model sequences in terms of the time. However the existing method can not exactly recognize the models because a false path can be generated from the candidates including not-hand regions such as background, elbow, and so on. In order to solve this problem, in this paper, we use the invariant moments extracted from the candidate regions of hand and compare the similarity of invariant moments among candidate regions. The similarity is utilized as a weight and the corresponding value is applied to the matching cost between the model sequence and the query sequence. Experimental results have shown that the proposed method can recognize the dynamic hand gestures in the various backgrounds. Moreover, the recognition rate has been improved by 13%, compared with the existing method.