• Journal of Drive and Control
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• v.17 no.3
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• pp.26-32
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• 2020

In modern society, the energy-saving problem of industrial vehicles is economically and environmentally critical. Energy savings using the potential energy of forklifts are one of the viable solutions to resolving this problem. The basic concept of this study is to operate the hydraulic motor and recharge the battery using the flow rate from the cylinder when loading heavy objects and lowering the fork. To save energy, the torque and rotational speed of the generator should be optimized according to the load and descent speed to increase efficiency. To this end, we propose a system that optimizes energy saving efficiency by controlling the swashplate angle of the variable hydraulic motor through the GA(Genetic-Algorithm). The results were verified by building and comparing fixed motor models and variable motor models using the AMEsim. The results of the study show that the proposed optimized swashplate angle increases the energy saving efficiency by approximately 6%-8%, depending on the working conditions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.101-104
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• 2007

The MFC makes the region in the player object center and it judges a relation the object. But it searches the objects which are not relation to game. Consequently, it decreases the speed of game and it recognizes a dangerous characteristic. In this paper, in order to complement a weak point, it applied the avoidance rule of the flocking in npc object. Consequently, the npc object has the concept of range of vision and proposed the method which is possibility of closing the speed decrease of game. This time 2 condition which is proposed must be satisfactory. The method that proposed will play an important role in development of a 3D FPS games.

• Physical Therapy Korea
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• v.26 no.1
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• pp.1-7
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• 2019

Background: The Microsoft Kinect which is a low-cost gaming device has been studied as a promise clinical gait analysis tool having satisfactory reliability and validity. However, its accuracy is only guaranteed when it is properly positioned in front of a subject. Objects: The purpose of this study was to identify the error when the Kinect was positioned at a $45^{\circ}$ angle to the longitudinal walking plane compare with those when the Kinect was positioned in front of a subject. Methods: Sixteen healthy adults performed two testing sessions consisting of walking toward and $45^{\circ}$ obliquely the Kinect. Spatiotemporal outcome measures related to stride length, stride time, step length, step time and walking speed were examined. To assess the error between Kinect and 3D motion analysis systems, mean absolute errors (MAE) were determined and compared. Results: MAE of stride length, stride time, step time and walking speed when the Kinect set in front of subjects were investigated as .36, .04, .20 and .32 respectively. MAE of those when the Kinect placed obliquely were investigated as .67, .09, .37, and .58 respectively. There were significant differences in spatiotemporal outcomes between the two conditions. Conclusion: Based on our study experience, positioning the Kinect directly in front of the person walking towards it provides the optimal spatiotemporal data. Therefore, we concluded that the Kinect should be placed carefully and adequately in clinical settings.

• Physical Therapy Korea
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• v.23 no.3
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• pp.1-10
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• 2016

Background: Gait problems appear in most stroke patients. Commonly, stroke patients show the typical abnormal gait patterns, such as circumduction, genu recurvatum, and spastic paretic stiff-legged gait. An inclined treadmill gait exercise is good for gait problems of stroke patients. In addition, the backward walking training has been recommended in order to improve the component of the movement for the forward walking. Objects: The purpose of this study to investigated the effects of backward walking with inclined treadmill training on the gait in chronic stroke patients. Methods: A total of 30 volunteers were randomly allocated to two groups that walked on an inclined treadmill: the experimental group ($n_1=15$), which walked backward, and the control group ($n_2=15$), which walked forward. To measure the improvement of the patients' gait, a Figure of Eight Walking Test (F8W), Four Square Step Test (FSST), and Functional Gait Assessment (FGA) were performed. We also measured spatio-temporal gait variables, including gait speed, cadence, stride length, and single limb support using a three-axial wireless accelerometer. The measurements were taken before and after the experiment. The Wilcoxon signed-rank test was used to compare both groups before and after the interventions. The Mann-Whitney U test was used for the comparisons after the interventions. The statistical significance was set at ${\alpha}=.05$. Results: Before and after experiment, all dependent variables were significantly different between the two groups (p<.05). As compared to the control group, the experimental group showed more significant improvements in F8W, FSST, speed, cadence, stride length, and single limb support (p<.05); however, FGA in this group was not significantly different from the control (p>.05). Conclusion: Our results suggest that backward walking on an inclined treadmill is more effective for improving the gait of stroke patients than forward walking.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.2
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• pp.111-119
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• 2011

Recently, the performances of speed and accuracy are enhanced in machine tools. The high speed of the machine tools usually causes harmful thermal displacements on the objects. To reduce the thermal displacements, machine tools generally adopt oil coolers with precise temperature control function. This study aims at precise control of oil outlet temperature in the oil coolers with hot-gas bypass manner based on PI control logic. The control system was designed for obtaining steady state error within ${\pm}0.1^{\circ}C$ and maximum overshoot with 0.8% even though abrupt disturbances are added to the system. We showed that the PI gains could be easily decided by numerical simulations using practical transfer function which got experiments. Also, transient characteristics could be improved significantly by reflecting the inlet temperature of an evaporator to the output of a controller feedforwardly considering periodic abrupt disturbances. Through some experiments, excellent control performances were established by the suggested control.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.3
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• pp.237-246
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• 2001

A high speed context-free marker-controlled and minima imposition-free watershed transform is proposed for efficient multi-object detection and segmentation from a complex background. The context-free markers are extracted from a complex backgrounded multi-object image using a noise tolerant attention operator. These make marker-controlled watershed possible for the over-segmentation reduction without region merging. The proposed method presents a marker-constrained labeling that can speed up the segmentation of a marker-controlled watershed transform by eliminating the necessity of the minima imposition. Simulation results show that the proposed method can efficiently detects and segments multiple objects from a complex background while reducing over- segmentation and the computation time.

• Journal of the Korea Society of Computer and Information
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• v.16 no.5
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• pp.61-71
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• 2011

To measure the fatigue of metallic objects at high speed vibration while non-contact precision displacement measurement on how to have a lot of research conducted. Noncontact high-speed vibration detection sensor of the eddy current sensors and laser sensors are used, but it is very expensive. Recently, High-speed vibrations detection using an inexpensive inductive sensor to have been studied, but is still a beginner. In this paper, a new design of an inexpensive inductive proximity sensor has been suggested in order to measure high frequency dynamic displacements of metallic specimens in a noncontact manner. Detection of the existing inductive sensors, detection, integral, and amplified through a process to detect the displacement noise due to weak nature of analog circuits and integral factor in the process of displacement detection is slow. The proposed method could be less affected by noise, the analog receive and high-speed signal processing is a new way, because AD converter (Analog to Digital converter) without using the vibration frequency signals directly into digital signals are converted. In order to evaluate the sensing performance, The proposed sensor module using non-contact vibration signals were detected while shaker vibration frequencies from 30Hz to 1,100 Hz at intervals of vibrating metallic specimens. Experimental results, Vibration frequency detection range of the metallic specimins within close proximity to contactless 5mm could be measured from DC to 1,100Hz and vibration amplitude of the resolution was $20{\mu}m$. Therefore, the proposed non-contact inductive sensor module for precision vibration detection sensor is estimated to have sufficient performance.

• Journal of the Korea Society of Computer and Information
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• v.3 no.2
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• pp.57-67
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• 1998

In order to extract the contour of interesting object in the image, Kass suggested the Active Contour Model called "Snakes" The speed of this model is slow and this model is sensitive of initialization. In order to improve these problems, Gunn extracted the accurate contour by using two initializations, and operated to less sensitive of initialization. This method could extract more accurate contour than the existing method, but it had no effect in the speed and it was sensitive of noise. This paper applied to the Energy Minimization Algorithm about only the pixel within the window applying the window of $8{\times}8$ size at each contour point consisting Snakes in order to solve these problems. In order to less sensitive of noise which exists within image, it suggests a method that moves the window to vertical direction for the gradient of each contour point.our point.

• Journal of Broadcast Engineering
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• v.25 no.3
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• pp.362-373
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• 2020

Recently, as autonomous vehicles and intelligent CCTV are growing more interest, the efficient object detection is essential technique. The DPM(Deformable Part Models) which is basis of this paper have used a typical object system that represents highly variable objects using mixtures of deformable part for object. Although it shows high detection performance by capturing part shape and configuration of object model, but it is limited to use in real application due to the complicated algorithm. In this paper, instead of image feature pyramid that takes up a large amount of computation in one part of the detector, we propose a method to reduce the computation speed by reconstructing a new image feature pyramid that uses adaptive bilinear interpolation of feature maps obtained on a specific image scale. As a result, the detection performance for object was lowered a little by 2.82%, however, the proposed detection method improved the speed performance by 10% in comparison with original DPM.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.2
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• pp.692-712
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• 2022

Buoys used for Aid to Navigation systems are widely used to guide the sea paths and are powered by batteries, requiring continuous battery replacement. However, since human labor is required to replace the batteries, humans can be exposed to dangerous situation, including even collision with shipping vessels. In addition, Maritime sensors are installed on the route signs, so that these are often damaged by collisions with small and medium-sized ships, resulting in significant financial loss. In order to prevent these accidents, maritime object detection technology is essential to alert ships approaching buoys. Existing studies apply a number of filters to eliminate noise and to detect objects within the sea image. For this process, most studies directly access the pixels and process the images. However, this approach typically takes a long time to process because of its complexity and the requirements of significant amounts of computational power. In an emergent situation, it is important to alarm the vessel's rapid approach to buoys in real time to avoid collisions between vessels and route signs, therefore minimizing computation and speeding up processes are critical operations. Therefore, we propose Fast Connected Component Labeling (FCCL) which can reduce computation to minimize the processing time of filter applications, while maintaining the detection performance of existing methods. The results show that the detection performance of the FCCL is close to 30 FPS - approximately 2-5 times faster, when compared to the existing methods - while the average throughput is the same as existing methods.