• Journal of Forest and Environmental Science
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• v.34 no.6
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• pp.419-428
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• 2018

Spatial point-patterns analyses were conducted to provide insight into the ecological process behind competition and mortality in two lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) stands, one in the Lower Foothills, and the other in the Upper Foothills natural subregions in the boreal forest of Alberta, Canada. Spatial statistical tests were applied to live and dead trees and included Clark-Evans nearest neighbor statistic (R), nearest neighbor distribution function (G(r)), and a variant of Ripley's K function (L(r)). In both lodgepole pine plots, the results indicated that there was significant regularity in the spatial point-pattern of the surviving trees which indicates that competition has been a key driver of mortality and forest dynamics in these plots. Dead trees generally showed a clumping pattern in higher density patches. There were also significant bivariate relationships between live and dead trees, but the relationships differed by natural subregion. In the Lower Foothills plot there was significant attraction between live and dead tees which suggests mainly one-sided competition for light. In contrast, in the Upper Foothills plot, there was significant repulsion between live and dead trees which suggests two-sided competition for soil nutrients and soil moisture.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.701-706
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• 2006

This paper describes an attempt to develop a practical method for the measurement of dead load stress in existing concrete bridges. In most cases, the dead load stress was determined by various theoretical calculations. However, the theoretical calculation cannot always provide a sufficient information on the current stress state due to lots of uncertainty. The key idea incorporated with this paper is the partial sectioning method which is able to estimate current stress state in concrete bridges subjected to dead load. The proposed method is applied to the safety assessment of actual concrete bridges and the applicability of this system is investigated.

• Journal of Information Processing Systems
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• v.19 no.5
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• pp.614-630
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• 2023

Dead trees significantly impact forest production and the ecological environment and pose constraints to the sustainable development of forests. A lightweight YOLOv4 dead tree detection algorithm based on unmanned aerial vehicle images is proposed to address current limitations in dead tree detection that rely mainly on inefficient, unsafe and easy-to-miss manual inspections. An improved logarithmic transformation method was developed in data pre-processing to display tree features in the shadows. For the model structure, the original CSPDarkNet-53 backbone feature extraction network was replaced by MobileNetV3. Some of the standard convolutional blocks in the original extraction network were replaced by depthwise separable convolution blocks. The new ReLU6 activation function replaced the original LeakyReLU activation function to make the network more robust for low-precision computations. The K-means++ clustering method was also integrated to generate anchor boxes that are more suitable for the dataset. The experimental results show that the improved algorithm achieved an accuracy of 97.33%, higher than other methods. The detection speed of the proposed approach is higher than that of YOLOv4, improving the efficiency and accuracy of the detection process.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2803-2806
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• 2003

In this paper considers the design of the effective controllers for the plant with an integrator and a long dead time. The structure of the new DTC(Dead Time Compensator) that has an additive filter is proposed. Our DTC shows the improved performance in set-point response and disturbance rejection. Especially the bad effect of the long dead time in the disturbance rejection is fairly reduced by using the additive filter. illustrative examples are provided to show the availability of the proposed controller.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.425-428
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• 2000

A new dead time compensation method using time delay control approach is presented. The dead time in switching pattern cause the voltage distortion and it can be considered as the disturbance voltage. In this paper the disturbance voltage is estimated using time delay control and the estimated disturbance voltage is summed with voltage command in predictive current control by a feed-forward. The proposed scheme is implemented on a PMSM and the effectiveness is verified through comparative simulation.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.252-255
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• 1999

A new dead-time compensation method using a disturbance observer is proposed. The dead-time causes the voltage distortion and it can be considered as the disturbance voltage. In this paper, the disturbance voltage is estimated by minimal order observer in the d-q frame and the estimated disturbance voltage is summed with voltage command by a feed-forward. The experiments are carried out for the DSP-based BLDC motor drive system and the results show the effectiveness of the proposed method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.9
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• pp.699-705
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• 2002

The present study discusses the deviation from the pure dead-time model of passive scalars such as temperature and concentration in the Poiseulle flow Even in the case of no thermal diffusion, there exists a substantial amount of damping and large deviation of phase lag from that computed by the traditional dead-time model after only 10 diameter downstream. These are caused by the phase difference of temperature in the radial direction due to the nonuniform velocity distribution. In the presence of thermal diffusion, damping is more pronounced.

• Proceedings of the KIEE Conference
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• summer
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• pp.1394-1396
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• 2004

Study passing method of AC/DC Dead ection of urban train and operation time of related device. And search the reason for operation of MCB(Main Curcuit Breaker) and find the safe method to pass dead section.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.675-677
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• 2004

This paper presents a nonlinear controller design for optical disk drive systems to improve anti-shock performance. The nonlinear anti-shock controller is added parallel to the original linear servo control loop. In the previous work, dead-zone nonlinear element is used for nonlinear controller and PID control method is used for linear controller. Although this strategy improves anti-shock performance, it has a narrow stability bound. In this paper, we propose dead-zone with saturation nonlinear element for the nonlinear controller. Since this nonlinear element improves stability margin, we can use higher gain of dead-zone than the controller with dead-zone only. In the linear controller design, we show that lead-lag control has improved stability margin over PID control. Numerical simulation results show that the proposed method can get better performance to the external shock than previously proposed method.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.155-159
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• 2001

In this paper, an on-line dead-time compensation method based on a time delay control approach is presented. The disturbance voltages caused by the dead time are estimated in an on-line manner by the time delay control without any additional circuits and off-line experimental measurements. And the estimated disturbance voltages are fed to voltage references in order to compensate the dead-time effects. The proposed method is applied to a PM synchronous motor drive system and implemented by using software of a digital signal processor (DSP) TMS320C31. Experiments are carried out for this system and the results well demonstrate the effectiveness of the proposed method.