• Journal of the Korean Society of Safety
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• v.24 no.6
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• pp.136-143
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• 2009

The injuries as a result of fall accidents is the one of the most common kind of injuries in Korea, especially fall from height is the top most common kind for fatal injuries. Futhermore, the number of fall injuries in manufacturing industry has been steadily increasing from 2000 to 2007. In 2007 the number of fall fatal injuries increased 10.6 % in comparison with the number in 2006. These numbers are 6~17 times higher than those for foreign countries such as the U.K and the USA. So, it is needed to make a study to reduce these numbers for manufacturing industry. To get the goals, we did research as followings. First, this study analyzed statistics by industry, by fall height, by common agent and so on to gain an insight into real aspect of fall injuries. It showed that ladder is the commonly cited agent for manufacturing industry, and 3 risky activities ; the ladder work, the load/unload work, and the maintenance work. Secondly, this study made a survey of manufacturing workers for their understandings of the most 3 risky activities. It showed that 'tendency to work easily' and 'difficulty of applying measures due to inherent working conditions' are main reasons for workers not to implement the preventive measures against the fall accidents. Thirdly, this study tested the slip characteristics of ladder base and lungs. The tests were done based on ANSI standard and KS. In addition to the standard condition, this study performed slip tests in wet and sandy conditions and compared the results with the those of standard condition. It showed that friction coefficient is standard condition > wet condition > sandy condition, and the friction coefficient of ladder for sandy condition is measured to be reduced by 63.9% compared with that for standard condition. Finally, this study developed safety work models for using of portable ladders in consideration of the safety standards of foreign countries such as the U.K, the USA, and the Australia.

• The Safety technology
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• no.55
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• pp.66-69
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• 2002

• Proceedings of the KIEE Conference
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• 1979.08a
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• pp.48-49
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• 1979

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1984.10a
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• pp.96-96
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• 1984

• The Safety technology
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• no.54
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• pp.64-69
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• 2002

• Bulletin of the Korean Chemical Society
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• v.19 no.5
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• pp.516-518
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• 1998

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.4
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• pp.49-55
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• 2006

In industrial control system used by Programmable Logic Controller(PLC), ladder Diagram(LD) is the must widely utilized and plays an important role in industrial control system. But recently, the study about Sequential Function Chart(SFC) is performed actively. When we program by SFC, generally, we design one routine from start to end. This method is difficult to design, and we often make mistakes. In this paper, we propose the method that we compose each sub-system after we design each sub-system and confirm his feasibility through an actual examples.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.818-829
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• 2003

A cooperating control algorithm for two nonholonomic mobile robots is proposed. The task is composed of collision avoidance against obstacles and carrying a ladder. The front robot and the rear robot are called the leader and the follower, respectively. Each robot has a nonholonomic constraint so it cannot move in perpendicular directions. The environment is initially supposed to be unknown except target position. The torque that drives leader is determined by distance between the leader and the target position or the distance between it and the obstacles. The torque by target is attractive and the torque by obstacles is repulsive. The two mobile robots are supposed to be connected by link that can be expanded and contracted. The follower computes its torque using position and orientation information from the leader by communication. Simulation results show that the robots can drive to target position without colliding into the obstacles and maintain the distance in the allowable range.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1424-1429
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• 2003

In this paper, the design method of sliding mode control (SMC) system for SISO linear system is discussed. First, we consider the similarity between the design method of sliding mode hyper plane using the strict positive realness and the characteristics of zeros of feedback system and the design method of simple adaptive control. Based on such a consideration, we propose the new design method of SMC system using parallel dynamic compensator. As a result, SMC system can be constructed only with the derivative of output signal for controlled plant. The performance of SMC system designed by proposed method is confirmed through the numerical example.

• Journal of the Korean Ceramic Society
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• v.25 no.4
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• pp.309-314
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• 1988

In this study, the effect of the size of sintered body on resonant and filter characteristics in Pb(Sn1/2Sb1/2)O3-PbTiO3 piezo-electric system were investigated. The attenuation characteristics of ring-dot type and ladder type filter were also investigated. As the size of sintered body was decreased, the resonant characteristic(Fr, Fa) and the center frequency(Fo) were increased. As the poling field was increased, the Kp and bandwidth were increased. The big difference between rign-dot type and ladder type was the sharpness of bandwidth, selectivity and the movement of center frequency.