• Journal of the Korean Society of Visualization
• /
• v.17 no.3
• /
• pp.52-58
• /
• 2019

Thermal performance and flow patterns inside the closed loop pulsating heat pipe (CLPHP) were experimentally investigated. For investigating the effect of working fluids, CLPHP was filled with various working fluids including methanol, acetone and ethanol. The thermal resistance was calculated by temperatures in evaporator and condenser and flow patterns were visualized by a digital camera. The thermal resistances for all fluids were decreased as the heat increases. Flow patterns change from static slug to elongated slug flows, bulk circulation and annular flows as the heat increases. Dry-out occurs after annular flows. For reasonable comparison of thermal performances, normalized CHF, Kutateladze number (K_u), was compared. Even though ethanol has smallest CHF, K_u of ethanol is similar with that of methanol. In addition, acetone has the highest K_u that means CLPHP with acetone provides the higher thermal performance compared with CLPHP with other fluids.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.772-777
• /
• 2003

A vision-based tool position estimation system for the inspection and maintenance manipulator working inside the steam generator bowl of nuclear power plants can help human operators ensure that the inspection probe or plug are inserted to the targeted tube. Some previous research proposed a simplified tube position verification system that counts the tubes passed through during the motion and displays only the position of the tool. In this paper, by using a general camera calibration approach, tool orientation is also estimated. In order to reduce the computation time and avoid the parameter bias problem in an ellipse fitting, a small number of edge points are collected around the large section of the ellipse boundary. Experiment results show that the camera calibration parameters, detected ellipses, and estimated tool position are appropriate.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.9 no.2
• /
• pp.255-260
• /
• 2014

Recently infrared cameras have been widely used to diagnosis degradation status of the power substitution system. At the place of high magnetic field, however, electronic parts of infrared camera take a place problem that is not reasonable working due to high magnetic field. To solve this problem, we may generally use reflector, it has a problem that the performance of reflection degrade caused by flexure of the reflector. In this paper, in order to overcome these problem, technique of design for reflector is proposed to reduce error and to increase measurement efficiency. The reflector is made by coating using aluminum on the acrylic sheet.

• The KIPS Transactions:PartD
• /
• v.10D no.2
• /
• pp.337-342
• /
• 2003

In this paper, a web based remote control system located at too dangerous field to access for the worker. The system was designed and implemented for three-dimensional stereo camera connected to web server which can be controlled easily by client side person working in the safe monitoring room. The user in the client side can control the vergence/focus control and zoom-in/out and pan/tilt functions through an user interface. The user interface for remote control environment was designed and implemented with Java applet mechanism, and was tested the operation result of the system.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.2063-2065
• /
• 2003

The control rod drive mechanisms in a reactor head are arranged too narrow for a human worker to approach. Moreover, the working environment is in high radiation area. In order to inspect defections in the surfaces of the reactor head and welding parts, a visual inspection device that can approach such a narrow and high radiation area is required. This paper introduces a tele-operated mobile robot for visual inspection of a reactor head, which has pan/tilt camera, fixed rear camera, ultrasonic collision detection system, and so on. Moreover, the host controller and digital video logging system are developed and integrated control software is also developed. The robot is operated by a wireless control, which gives flexibility for the inspection.

• International Journal of Internet, Broadcasting and Communication
• /
• v.12 no.3
• /
• pp.171-176
• /
• 2020

This paper presents an implementation of a gesture recognition platform that can be used in a factory workplaces. The platform consists of signages that display worker's job orders and a control center that is used to manage work orders for factory workers. Each worker does not need to bring work order documents and can browse the assigned work orders on the signage at his/her workplace. The contents of signage can be controlled by worker's hand and arm gestures. Gestures are extracted from body movement tracked by 3D depth camera and converted to the commandsthat control displayed content of the signage. Using the control center, the factory manager can assign tasks to each worker, upload work order documents to the system, and see each worker's progress. The implementation has been applied experimentally to a machining factory workplace. This flatform provides convenience for factory workers when they are working at workplaces, improves security of techincal documents, but can also be used to build smart factories.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.9
• /
• pp.2191-2204
• /
• 1993

A sensor system has been developed to measure the posture(position and orientation) of mobile robots working in industrial environments. The proposed sensor system consists of a CCD camera, retro-reflective landmarks, a strobe unit and an image processing board. The proposed hardware system can be built in economic price compared to commercial vision systems. The system has the capability of measuring the posture of mobile robots within 60 msec when a 386 personal computer is used as the host computer. The experimental results demonstrated a remarkable performance of the proposed sensor system in the posture measurement of mobile robots - the average error in position is less than 3 mm and the average error in orientation is less than 1.5.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.1010-1015
• /
• 2003

Bubble growth on microheater has been experimentally investigated in this study. The experiment was performed using platinum microheaters having dimensions of 300 ${\mu}m$ or 50 ${\mu}m$ in length, 20 ${\mu}m$ or 5 ${\mu}m$ in width, and $0.2{\pm}0.01$ ${\mu}m$ in thickness. A high speed video camera was used to observe bubble growth at 2,000 frames per second. Microheater temperature was measured at the rate of 300 Hz. with a data acquisition system. Bubble nucleation frequency increased with working fluid temperature. Although the slope of temperature drop was similar in all cases, the magnitude of temperature drop was different. The temperature profiles and the high speed camera images were combined to explain temperature drop.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.6
• /
• pp.5-14
• /
• 1998

In this paper we propose a new approach to the development of the automatic vision system to examine and repair the steam generator tubes at remote distance. In nuclear power plants, workers are reluctant of works in steam generator because of the high radiation environment and limited working space. It is strongly recommended that the examination and maintenance works be done by an automatic system for the protection of the operator from the radiation exposure. Digital signal processors are used in implementing real time recognition and examination of steam generator tubes in the proposed vision system. Performance of proposed digital vision system is illustrated by simulation and experiment for similar steam generator model.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.477-481
• /
• 2002

Grinding which is the final finishing step in the machining processes plays an important role fur precision manufacturing because it directly affect the product quality. Since the ground surface is affected by the states of grains and voids on the grinding wheel surface, the wheel should be dressed before the machined surface deteriorates over a quality limit. This paper describes a systematic approach to decide a proper dressing chance. A fabricated eddy current sensor and CCD camera are used to measure the loading on the working wheel surface and to visualize the wheel surface states respectively. The dressing chance can be properly decided through the relation between the variation of the thresholding image of the wheel and the machined surface roughness as the variation of the eddy current sensor output is greater than the detected value previously.