Byung-Hak Cho

Development of Automatic Cleaning Robot for Live-line Insulators

A new cleaning robot system for double tension insulator strings was developed to prevent an insulator failure, which can have severe effects on national security as well as national industry and economy. The robot moves along the insulator string using the clamps installed on its two moving bodies. Especially, unlike the existing cleaning robots using jets of water or water/air, the robot system adopts dry cleaning method using a rotating brush and a circular motion guide.

Development of robot mechanism for inspection of live-line suspension insulator string in 345kV power lines

A new inspection robot mechanism for live-line suspension insulator strings was developed to prevent an insulator failure in power transmission lines. By adopting a wheel-leg moving mechanism, the robot structure becomes very simple, small-sized and lightweight. In addition, this mechanism is superior in insulation to the existing ones, because the number of the insulators contacted by the mechanism is only one. Through experiments, we confirmed its effectiveness.

Implementation of Control System for Insulator Cleaning Robot

It is very important to maintain power transmission lines without a failure for stable power service without interruption. To prevent reduction of the insulation resistance of insulators, it is required to clean the insulators periodically. Working environment using jets of water by maintenance personnel is dangerous because insulators are located in a high place with a high voltage. Due to the working environment described above, cleaning efficiency and precision is low. To overcome such difficulties, an insulator cleaning robot has been developed. In this paper, the control system for insulator cleaning robot is designed and implemented in consideration of the characteristics of the robot and the insulators, and the validity of the implemented control system is shown via experiments

Design and control of 2kW class power takeoff unit for rotating body type wave energy converter

The hydraulic power takeoff converter has been commonly applied to the rotating body type wave energy converters. It is because the hydraulic converter is more suited for dealing with periodic oscillating property of the body in a cost effective way. In order to extract wave energy effectively, the pressure and flow rate of the working fluid in the hydraulic converter should be kept adequately reflecting the period and height of given ocean wave. The pressure and the flow rate of the working fluid have effects on providing desired phase between incident wave and rotating body, and achieving optimum amplitude for the rotating body, respectively. To accomplish these objects together, a flexible controller is required reflecting the large variety of real ocean wave conditions. If the desired flexibility is limited, this may seriously affect the energy absorbing efficiency. The controller is designed to maintain the pressure and the flow rate of the working fluid at an optimum condition according to the given incident waves.

Trajectory Control of Underwater Robot using Time Delay Control

In this paper, the trajectory control problem of an underwater robot is addressed. From the viewpoint of control engineering, trajectory control of the underwater robot is not an easy task due to its nonlinear dynamics, which includes various hydraulic forces such as buoyancy forces and hydrodynamic damping, the difference between the centers of buoyancy and gravity, and disturbances from a tether cable. To solve such problems, we applied Time Delay Control to the underwater robot. This control law has a very simple structure not requiring the nonlinear plant dynamics, and was proven to be highly robust against disturbances and uncertainties. We confirmed its effectiveness through experiments.

Development of a Live-line Insulator Inspection Tool System for 154 kV Power Transmission Lines

The current paper deals with a new live-line insulator inspection tool system that will be used by the Korea Electric Power Corporation for its 154 kV power transmission lines in 2011. Unlike the existing contact type tools, the developed inspection tool automates parts of the insulator inspection process using a sensor and an actuator. The tool sustains its weight independently, not by a lineman. In addition, the inspection tool measures the insulation resistance of an insulator together with its distribution voltage, thus providing more information for analysis and diagnosis. Such characteristics improve the systems operation efficiency, measurement reliability, and usability. We confirmed its effectiveness through live-line field tests with actual power transmission lines.

Establishment of field robot system for observation of power plant facilities

As power plant facilities are being deteriorated, their safety is getting more importance, and more routine surveillance is being required to preserve safety of the facilities. For this purpose, this paper presents a field robot system which performs the surveillance of power plant facilities instead of human workers from the viewpoint of the workerspsila safety and work efficiency.

Development of Thimble Handling System for Neutron Flux Mapping

The in-core neutron flux mapping system in a pressurized water reactor yields information on the neutron flux distribution in the reactor core at selected core locations by means of movable detectors. The obtained data are used to verify the reactor core design parameters. The detector cables run through guide tubes (thimbles), and typically thirty six to fifty thimbles are allocated in the reactor depending on the number of fuel assemblies. For reactor operation, the thimbles are inserted into nuclear fuel assemblies through conduits connected from the bottom of the reactor vessel to a seal table. During the plant refueling outage period, the thimbles are withdrawn up to 4 meters from the seal table, the height of fuel assemblies. Thimble handling work has been performed by maintenance personnel. Manual handling efficiency is low due to narrow and high-radiation working environment around the seal table. Besides, manual force exerted on the thimbles is not constant and usually does not have unique direction, which may cause serious damage to the thimbles. To overcome these difficulties, automatic handling system for in-core neutron flux mapping thimbles has been developed, and the validity of the developed system is shown via experiments