• Proceeding of EDISON Challenge
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• 제4회(2015년)
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• pp.207-211
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• 2015

In this paper, 2 kinds of models about bike frame are simulated with static structural analysis. A bike frame with diamond type is compared with another model that Down tube is eliminated from original diamond frame. About both types of models, Property of a material and conditions of restriction & load are the same. This study shows reinforcement effects of a partial frame by adding down tube and impacts generated by applying a load at the frame such as weak points & high stress parts as well as expected deformation. The structural result of this study indicates that the equivalent stress or total deformation decreases by 57.1% or 36.4%, respectively. Also stress concentration sites are leg connecting parts, front/rear wheels fixed region and Max deformation is generated from Seat tube. In conclusion, A Down tube is highly efficient as reinforcement than frame without non down tube. Furthermore, The safety rises in case of reducing top tube thickness and increasing a reinforcement at leg connecting parts or concentration regions.

• Advances in Computational Design
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• 제1권2호
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• pp.155-173
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• 2016

This paper presents a method of design for the energy harvesting of a piezoelectric cantilever beam. Vibration modes have strain nodes where the strain distribution changes in the direction of the beam length. Covering the strain nodes of the vibration modes with continuous electrodes effects a cancellation of the voltages outputs. The use of segmented electrodes avoids cancellations of the voltage for multi-mode vibration. The resistive load affects the voltage and generated power. The optimum resistive load is considered for segmented and continuous electrodes, and then the power output is verified. One of the effective parameters on energy harvesting performance is the existence of concentrated mass. This topic is studied in this paper. Resonance and off-resonance cases are considered for the harvester. In this paper, both theoretical and experimental methods are used for satisfactory results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• 제5권1호
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• pp.45-50
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• 2006

This paper shows a new precision actuator of MUTM(miniature universal testing machine) for the testing of compression and tensile load on the MEMS materials and structures. The MUTM consists of a sample holder, an ultraprecision precision actuator(tranlation stage) and load sensor. The precision actuator has been developed for generating displacements with nanometer accuracy and a dynamic range of 1mm simultaneously. In this paper, it can be made by using the displacement property of bi-morph type PZT, which is able to extend the long range(stroke) according to cantilever size. However, it is not enough to be generated for compression and tensile load in miniature universal testing machine. Therefore, three dozen bi-morph type PZTs are used for generating the load. The load and displacement of the precision actuator are 35g and 0.4mm respectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제59권8호
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• pp.1497-1505
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• 2010

The present study was performed to investigate the effect of aging on muscular activity of older subjects under the condition of fixed load muscle contraction. SEMG signals were recorded from old (46 women) and young (45 women) groups performing sustained isometric elbow flexion contraction with a fixed load during 30 seconds. Linear regression and mean square error (MSE) analysis with four characteristic variables (ARV, RMS, MDF, MNF) were used to compare the age-related difference (of local muscle fatigue and fluctuation of the amplitude and frequency) in the SEMG signal. The main results can be summarized as follows: During sustained muscle contraction with a fixed load: i) the MSE values of amplitude (ARV, RMS) and frequency (MDF, MNF) variables were more than 30% higher for the young than for the old adults; ii) the measures of local muscle fatigue (slope of the MDF and MNF) indicated greater fatigue in the old; and iii) the rate of increase of the SEMG amplitude was higher for the young than the old.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• 제32권2호
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• pp.35-39
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• 2000

Refining is very important process of fibers treatment for proper paper properties. An extent of refining is usually measured by freeness, although freeness gives complicated meanings. One of a direct way of studying the refining effects on pulp fibers is making photomicrographs of beaten fibers. The conventional microscopy like light microscopy(LM) and scanning electron microscopy(SEM) require to preserve the wet structure of pulp fibers morphologically since most of papermaking process is carried out almost entirely in water. Recently developed microscopy, especially confocal laser scanning microscopy(CLSM), offers the possibility of examining fully hydrated pulp fibers. Cross-sectional images of wet pulp fibers are also generated using optical sectioning by CLSM and image analysis in order to verify and quantify the extent of fiber wall swelling indicating the internal fibrillation. At low beating load such as 2.5 kgf, in the same freeness, breaking length is higher than that of high beating load such as 5.6 kgf. fiber wall thickness at low beating load is greater than that at high beating load. This result is accounted for the fact that internal fibrillation in the low beating load was high.

• Transactions of the Korean Society of Mechanical Engineers
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• 제18권7호
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• pp.1654-1663
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• 1994

Even if the ball bearing was conservatively designed considering the dynamic capacity and the rating life, sometimes the bearing was early failed on account of the misalignment and the lubricant contaminations etc. Misalignment was generated when bearing-shaft system transmitted large power and when the bearing was inadequately mounted. It was possible to predict the fatigue life of ball bearing under the misalignment considering the motions of ball, cage and raceway, and the factors of the effect on fatigue life. Misalignment affected on ball bearing as radial and moment load and the relationships between misalignment and moment were obtained. In this paper, the analysis of the load distributions between ball and raceway, and the prediction of fatigue life of deep groove ball bearing under radial and moment loads were carried out. And, the new formulation of equivalent dynamic load considering the effects of moment load was proposed.

• Transactions of the Korean Society of Automotive Engineers
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• 제23권2호
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• pp.239-245
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• 2015

In order to control the hybrid power system efficiently, the knowledge for the required load of the system is important. The agricultural tractor performs various farm works such as plow, rotary, and baler. When it performs rotary tillage and baler operation, the generated work load is analyzed. To analyze trend of work load, moving average technique is applied to the measurement data. Optimal control inputs for the two works are obtained from simulation using the dynamic programming. The novel fundamental control strategy for parallel hybrid tractor called Max. SOC is proposed.

• Proceedings of the KIPE Conference
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.86-88
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• 2007

In solar power system, the height and azimuth of the sun are important parameters which control generated power magnitude. The tracking method that controls the daily generation magnitude according to latitude and longitude using the two axles is often used in the existing sunlight tracking system today. In this two-axle PV track control system, the self-load is concentrated on one FRAME. It is influenced of the regular load, snow load and the wind load, etc. It is difficult to set up the system in the conventional building. This research is a development about the small-scale economy track device of independent load-dispersing solar generation system. The position tracking algorithm is through the new coordinates transformation calculating the height and azimuth of the sun.

• Journal of Information Processing Systems
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• 제17권2호
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• pp.297-305
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• 2021

Large amount of data is being generated in gaming servers due to the increase in the number of users and the variety of game services being provided. In particular, load balancing schemes for gaming servers are crucial consideration. The existing literature proposes algorithms that distribute loads in servers by mostly concentrating on load balancing and cooperative offloading. However, many proposed schemes impose heavy restrictions and assumptions, and such a limited service classification method is not enough to satisfy the wide range of service requirements. We propose a load balancing agent that combines the dynamic allocation programming method, a type of greedy algorithm, and proximal policy optimization, a reinforcement learning. Also, we compare performances of our proposed scheme and those of a scheme from previous literature, ProGreGA, by running a simulation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.694-699
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• 2005

This paper deals with a control technique of eliminating the transient vibration of a geared mechanical system. This technique is based on a model-based control with a rotational speed sensor in order to establish the damping effect at the driven machine part. A rotational speed sensor is installed in a driven gear, namely a bull gear. A control model is composed of a reduced-order mechanical part expressed as a transfer function between the rotational speed of the motor and that of the bull gear. This control model estimates a load speed after the rotational speed of the bull gear is acted on the transfer function. The difference between the estimated load speed and the motor speed is calculated dynamically and it is added to the velocity command to suppress the transient vibration generated at the load. This control technique is applied to a dies driving spindle of a form rolling machine. In this paper, the performance of this control method is examined by simulations. The settling time of the residual vibration generated at the loading inertia can be shortened down to about 1/2 of the uncompensated vibration level.