• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.651-657
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• 2012

In many control fields high position performance is essentially required in reducing the over-shoot phenomena which is produced by improving the quick response in starting and in minimizing the variation of the response characteristic on disturbance and load variation In this paper, the design method for a position control is suggested for constructing the PI-PD controllers by using an internal PD feedback loop in PI and PD control system. Applying this method to the position control system used a DC servo motor as a driver, the transfer PI and PD controllers are designed simultaneously and the coefficients of these controllers are determined by using the transfer function of a plant and a proportional coefficient from mathematical technique. From the result of computer simulation in PI-PD control system by applying this control technique, we can verify the usefulness of this method in rejecting of over-shoot of starting, compensating of response variation on the load variation, and shorting the settling time.

• Journal of Environmental Health Sciences
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• v.31 no.5 s.86
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• pp.423-430
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• 2005

This research was performed to evaluate the effectiveness of one- and dual-stage recycled-water systems in slurry bioreactor treatment for coal tar-contaminated soil. Silty loam soil was used for this research. Coal tar and 14 target PAHs (Polycyclic Aromatic Hydrocarbons) concentration in the soil were determined with gas chromatography. There was no significant difference between removal efficiencies of one- and dual-stage recycled water systems in case of about 4,000 mg coar tar/kg. However, the dual-stage system increased significantly the removal efficiency in case of about 20,000 mg coar tar/kg and the first-order kinetic constant of the system was over 1.5 times higher than that of one-stage recycled water system. 3-Ring compounds in PAHs was removed completely within 30 days of operation. Coar tar was removed in over 96% through biodegradation and removed in about 4% by evaporation. High correlation coefficient($r^2=0.91$) was found between water solubility and removal efficiency of the cyclic compounds.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.5
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• pp.1013-1027
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• 2011

In this paper we propose ATCS, a practical TCP protocol coding scheme based on network coding for satellite IP networks. The proposal is specially designed to enhance TCP performance over satellite networks. In our scheme, the source introduces a degree of redundancy and transmits a random linear combination of TCP packets. Since the redundant packets are utilized to mask packet loss over satellite links, the degree of redundancy is determined by the link error rates. Through a simple and effective method, ATCS estimates link error rates in real time and then dynamically adjusts the redundant factor. Consequently, ATCS is adaptable to a wide range of link error rates by coding TCP segments with a flexible redundancy factor. Furthermore, the scheme is compatible with traditional TCP variants. Simulation results indicate that the proposal improves TCP performance considerably.

• Fashion & Textile Research Journal
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• v.11 no.6
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• pp.918-924
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• 2009

As the population of overweight and obese children is rising rapidly around the world, there are many researches on purchasing and wearing children's clothing and optimal sizes, but researches on obese children are still inadequate. This study was carried out on 192 obese children over 75% in BMI. The purpose of the study was to set up the optimal interval of sizing system using the loss function which would be a guide for obese children for selecting ready to wear of suitable size. Introducing a loss function, which reflects how much the purchasing desire changes according to the difference, we formulate the problem and suggest a procedure to determine the optimal standard sizes minimizing the loss. These results were as follows ; In size chart of top's, 4 sizes had been determined by a loss function, had covered more than 91.1% of all subjects. In size chart of bottom's, 5 sizes had been determined by a loss function, had covered more than 87.0% of all subjects.

• Korean journal of food and cookery science
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• v.20 no.1
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• pp.63-75
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• 2004

This study was conducted to establish the hygiene standards for chicken entrees (deep-fried breast chicken, chicken and potato in red pepper paste and smothered chicken) served with in 3 different elementary school lunch programs during 2002. The study evaluated the layout characteristics of the food facilities, and determined the physical and microbiological hazards for the production of chicken entrees based on the HACCP(Hazard Analysis Critical Control Point) system. The kitchen layouts needed to be remodeled for the separation of soiled and clean work areas. The pH values for all items were over 6.0, which require careful attention. The microbial assessments of 3 chicken items revealed that the TPC, coliforms and Staphylococcus aureus were within normal ranges, but Salmonella was found at several stages in the production of all products, with the exception of smothered chicken. The bacterial counts of the kitchen utensils and cooks' hands exceeded acceptable limits, and workers' sanitary practices were poor in terms of sanitary handling and holding of foods and utensils. The CCPs determined related to the steps of receiving, cooking and breaking of egg shells. From our findings, it is recommended that chicken entrees should be prepared and served very carefully, as salmonella was detected at several stages during meal production, and the aim of the HACCP system is to secure against food-borne illnesses due to reckless school food service operations.

• Journal of Forest and Environmental Science
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• v.39 no.4
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• pp.254-260
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• 2023

A sensor system has been developed that uses an ultrasonic sensor to detect the downhill slope on the side of a forest road and prevents a vehicle-type forest machine from rolling down a mountainside. A specular reflection of ultrasonic wave might cause severe issues in measuring distances to targets. By investigating the installation angle of the sensor to minimize the negative effects of specular reflection, the installation angle of lateral monitoring ultrasonic sensor could be determined based on the width of road shoulder. Obstacles such as small rocks or piece of log in a forest road may cause the forest machine to be overturned while the machine riding over due to excessive its posture change. It was determined that the laser sensor could be a part of a sensor system capable of specifying the location and size of small obstacles. Not only this sensor system including ultrasonic and laser sensors can issue a warning of dangerous sections to drivers in forest forwarders currently in use, but also it can be used as a driving safety sensor in autonomous forest machine or remote-control forest machine in the future.

• Journal of Biosystems Engineering
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• v.33 no.2
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• pp.115-123
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• 2008

This study was conducted to develop an automatic soil water content control system for greenhouse, which consisted of drip irrigation nozzles, soil water content sensors, an on/off valve, a servo-motor assembly and a control program. The control logic adopted in the system was Ziegler-Nichols algorithm and rising time, time constant and over/undershoot ratio as control variables in the system was selected and determined by various control experiments to maintain small delay time and low overshoot. Based on the experimental results, it was concluded that the control system developed in the study could replace the unreliable conventional greenhouse soil water management.

• Journal of IKEEE
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• v.5 no.1 s.8
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• pp.35-42
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• 2001

This paper deals with an architecture of network-based control system using the CAN(Controller Area Network) protocol and its traffic analysis. It is difficult to determine an optimal network-based control architecture for a specific AGV(Autonomous Guided Vehicle) system with a manipulator arm. The fixed number of periodic messages to be occurred is pre-defined in the system. To determine whether the proposed system architecture is effective or not, we perform traffic analysis for the real-time communication of all messages. Through simulations, the range of transmission speed is found satisfying required conditions and the permissible number of additional sensors is investigated for improving the system performance, when the sampling periods of analog sensors are determined under fixed condition that the transmission speed is over 500Kbps.

• Journal of Astronomy and Space Sciences
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• v.33 no.4
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• pp.257-264
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• 2016

A planet revolving around binary star system is a familiar system. Studies of these systems are important because they provide precise knowledge of planet formation and orbit evolution. In this study, a method to determine the evolution of an exoplanet revolving around a binary star system using different rates of stellar mass loss will be introduced. Using a hierarchical triple body system, in which the outer body can be moved with the center of mass of the inner binary star as a two-body problem, the long period evolution of the exoplanet orbit is determined depending on a Hamiltonian formulation. The model is simulated by numerical integrations of the Hamiltonian equations for the system over a long time. As a conclusion, the behavior of the planet orbital elements is quite affected by the rate of the mass loss from the accompanying binary star.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.13 no.21
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• pp.25-28
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• 1990

In this paper we consider the one-period inventory model in which it is required to determine the selling quantity which maximizes the probability of realizing a predetermined level of profit L. The Assumptions used in this paper are willing to accept the rel life considerations, which are thestochasic supply, the discounted selling price and the discounted purchasing cost for the over-supply etc.