• Journal of Korean Institute of Industrial Engineers
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• v.32 no.3
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• pp.200-209
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• 2006

Load building is an important step to make the delivery supply chain efficient. We present a family of load makeup algorithms using market based control strategy, named LoadMarket, in order to build efficient loads where each load consists of a certain number of finished products having destinations. LoadMarket adopts Clark-Wright algorithm for generating initial endowment for Load Traders who cooperate to minimize either total travel distance or the variance with respect to the travel distances of loads by means of the spot market or double-sided auction market mechanism. The efficiency of the LoadMarket algorithms is illustrated using simulation based experiments.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.285-292
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• 2000

Though there has been increasing use of large diameter drilled shaft as a foundation structure of bridges, current practice for quality control is to confirm the minimum required load carrying capacity during construction stage. For economic and appropriate design of drilled shaft, it is necessary to evaluate the load transfer mechanism by pile load tests during initial stage of construction and to use the test results as a feedback to a revision of initial design. In this paper, results of load tests peformed at several domestic sites are presented to investigate the load transfer characteristics of large diameter drilled shaft. It was found that most of the load on piles is sustained by shaft friction and that only small portion of the load reaches the bottom of the drilled shaft. Some test results of drilled shaft by Pile Driving Analyzer performed at same sites are also presented to compare the load transfer characteristics interpreted from static pile load tests.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.2
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• pp.14-21
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• 1993

Pneumatic actuators have greater power to weight ratio than electric ones, but they have been rarely used as robotic actuators because of poor accuracy resulted from nonliearity of air. On the other hand, electric servo motors have glld controllability, but they have poor power to weight ratio. For the heavy load handling robot a combined actuating method was developed for vertical and horizontal axes of RISTBOT-ll which handles up to 250kgf load. In this paper, the control method is implemented and analyzed for the manufactured heavy load handling robot.

• Journal of Mechanical Science and Technology
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• v.20 no.11
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• pp.1823-1833
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• 2006

An immune algorithm is a kind of evolutional computation strategies, which is developed in the basis of a real immune mechanism in the human body. Recently, scientific or engineering applications using this scheme are remarkably increased due to its significant ability in terms of adaptation and robustness for external disturbances. Particularly, this algorithm is efficient to search optimal parameters against complicated dynamic systems with uncertainty and perturbation. In this paper, we investigate an immune algorithm embedded Proportional Integral Derivate (called I-PID) control, in which an optimal parameter vector of the controller is determined offline by using a cell-mediated immune response of the immunized mechanism. For evaluation, we apply the proposed control to mitigation of vibrations for nonlinear structural systems, cased by external environment load such as winds and earthquakes. Comparing to traditional controls under same simulation scenarios, we demonstrate the innovation control is superior especially in robustness aspect.

• Journal of the Korea Society of Computer and Information
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• v.5 no.2
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• pp.98-104
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• 2000

One of the main features of ABR service is the employment of a rate-based flow control mechanism, and congestion control plays an important role in the effective and stable operation of ATM networks Feedback from the network switches to the end system gives users the information necessary to adjust transmission rates appropriately according to the current networks load. Congestion controls by feedback mechanism are classified as EFCI and ER mode. We analyze the performance of EFCI and ER and propose a new ABR traffic control strategy by integrating EFCI and ER modes to improve the traditional traffic control. Through the distributed simulation. the performance improved by the proposed control strategy is analyzed.

• Journal of Drive and Control
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• v.16 no.3
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• pp.8-15
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• 2019

Wheelchair users experience difficulty when using transportation. This is because wheelchair users must use transportation means together with wheelchairs. Therefore, in this paper, we developed a wheelchair storage system for passenger's car trunk. The mechanism is designed to allow a wheelchair and the device to be housed simultaneously in the narrow space of the trunk of the sedan passenger car. Additionally, this wheelchair storage system has implemented an initial load reduction mechanism that can mechanically reduce the initial load. This wheelchair storage system verified the system's operability through the production of the prototype. This system was actually installed in the trunk of the sedan passenger's car to verify the storage process. The operation and storage process of the wheelchair storage system was been perfectly verified. This wheelchair storage system will help a lot of self-driver or an assistant (female or elderly) who use wheelchairs.

• Journal of Drive and Control
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• v.11 no.2
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• pp.9-15
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• 2014

This paper deals with the issue of force synchronizing control for the clamping servomechanism of injection molding machines. Prior to the controller design, a virtual design model has been developed for the clamping mechanism with hydraulic systems. Then, a synchronizing controller is designed and combined with an adaptive feedforward control in order to accommodate the mismatches between the real plant and the linear model plant used. As a disturbance, the leakage due to the ring gap with relative motion in the cylinder has been introduced. From the robust force tracking simulations, it is shown that a significant reduction in the force synchronizing error is achieved through the use of a proposed control scheme.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.307-310
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• 2005

Most of the electric power in the power system of South Korea is flowing from the south area to the north area, Seoul, in the capital of South Korea. Almost of the needs of the electric power in the capital area are about 43% of the total loads and generation plants are mainly located in the south area of South Korea. As mentioned the earlier characteristic, transmission congestion is one of the important research issues. Because of the limits of the power flows from the south to the north which are anticipated to be increased more and more in the future, these congestion situations may cause a serious voltage stability problem in emergency of the power system. Accordingly, we are interested in an interruptible load control program so as to solve this problem in emergency. This problem can be solved by an interruptible load management in emergency, however, the systematic and effective mechanism has not been presented yet. In this paper, the algorithm of interruptible load management plan using the line sensitivity to the loads for the transmission congestion management in emergency is presented. The proposed method is applied to 6-Bus sample system and their results are presented.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.7
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• pp.2512-2531
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• 2014

We propose a new Distributed Denial of Service (DDoS) defense mechanism that protects http web servers from application-level DDoS attacks based on the two methodologies: whitelist-based admission control and busy period-based attack flow detection. The attack flow detection mechanism detects attach flows based on the symptom or stress at the server, since it is getting more difficult to identify bad flows only based on the incoming traffic patterns. The stress is measured by the time interval during which a given client makes the server busy, referred to as a client-induced server busy period (CSBP). We also need to protect the servers from a sudden surge of attack flows even before the malicious flows are identified by the attack flow detection mechanism. Thus, we use whitelist-based admission control mechanism additionally to control the load on the servers. We evaluate the performance of the proposed scheme via simulation and experiment. The simulation results show that our defense system can mitigate DDoS attacks effectively even under a large number of attack flows, on the order of thousands, and the experiment results show that our defense system deployed on a linux machine is sufficiently lightweight to handle packets arriving at a rate close to the link rate.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.435-438
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• 2002

In this study, a new passive aerodynamic control method is proposed. Control plate which is oscillated by TMD-like mechanism makes flutter stabilizing airflow. Effectiveness of proposed model is verified by experimental and analytical study. In addition, various parameters of the proposed system are investigated. Applicability to long span bridge is also examined. According to the research results, proposed model is very effective in suppressing flutter, and it also shows remarkable robustness.