• Safety and Health at Work
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• v.10 no.1
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• pp.125-129
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• 2019

The ultimate goal of the quality control program for special periodic health examination agencies is to diagnose the health condition of a worker correctly, based on accurate examination and analysis skills, leading to protect the worker's health. The quality control program on three areas, chemical analysis for biological monitoring since 1995, and pneumoconiosis, audiometric testing since 1996, has contributed to improve the reliability of occupational health screenings by improving the issues including standardization of testing methods, tools, diagnostic opinions, and reliability of analysis for biological monitoring. It has contributed to improving the reliability of occupational health monitoring by rectifying the following issues associated with previous monitoring: absence of standardized testing methods, testing tools that are not upgraded, mismatching diagnostic opinions, and unreliable results of biological specimen analysis. Nevertheless, there are issues in need of further improvement such as lack of expertise or the use of inappropriate method for health examination, and passive and unwilling participation in the quality control. We suggested solutions to these problems for each area of quality control program. Above all, it is essential to provide active support for health examiners to develop their expertise, while encouraging all the health screening agencies, employers, and workers to develop the desire to improve the system and to maintain the relevance.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.10
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• pp.792-798
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• 2002

The spectrum of impulse response signal from an impulse hammer testing is widely used to obtain frequency response function (FRF) of the structure. However the FRFs obtained from impact hammer testing have not only leakage errors but also finite record length errors when the record length for the signal processing is not sufficiently long. The errors cannot be removed with the conventional signal analyzer which treats the signals as if they are always steady and periodic. Since the response signals generated by the impact hammer are transient and have damping, they are undoubtedly non-periodic. It is inevitable that the signals be acquired for limited recording time, which causes the finite record length error and the leakage error. In this paper, the errors in the frequency response function of multi degree of freedom system are formulated theoretically. And the method to remove these errors is also suggested. This method is based on the optimization technique. A numerical example of 3-dof model shows the validity of the proposed method.

• Progress in Medical Physics
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• v.28 no.4
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• pp.197-206
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• 2017

We develop guidelines for the quality assurance of radiation treatment planning systems (TPS) by comparing and reviewing recommendations from major countries and organizations, as well as by analyzing the AAPM, ESTRO, and IAEA TPS quality assurance guidelines. We establish quality assurance items for acceptance testing, commissioning, periodic testing, system management, and security, and propose methods to perform each item within acceptable standards. Acceptance includes tests of hardware and network environments, data transmission, software, and benchmarking as specified by the system supplier, and apply the IAEA classification criteria. Commissioning includes dosimetric and non-dosimetric items for assessing TPS performance by applying the AAPM classification criteria and the latest technical items from the IAEA. Periodic quality assurance tests include daily, weekly, monthly, yearly, and occasional items by applying the AAPM classification criteria. System management and security items include the state and network connectivity of TPS, periodic data backup, and data access security. The guidelines for TPS quality assurance proposed in this study will help to improve the safety and quality of radiotherapy by preventing incidents related to radiotherapy.

• Journal of Welding and Joining
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• v.22 no.5
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• pp.32-37
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• 2004

Application of bonding by adhesives can be found in many industries, particularly in advanced technological domains such as aeronautical and space, automobile and electronics industries. Periodic inspection with conventional ultrasonic NDE techniques is capable of indicating the presence and possible location of crack. Continuous ultrasonic attenuation monitoring has potential to supply information. This article discusses the use of pulse-echo ultrasonic testing for the inspection of adhesive bonds between metal sheets. The method is based on the measurement of the reflection coefficient at the metal/adhesive interface. By means of a control experiment it is shown that Quantitative Nondestructive Evaluation in Adhesive Joints are evaluated together with Ultrasonic Testing and Fracture Testing.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.363.2-363
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• 2002

The spectrum of impulse response signal from an impulse hammer testing is widely used to obtain frequency response function(FRF) of the structure. However the FRFs obtained from impact hammer testing have not only leakage errors but also finite record length errors when the record length for the signal processing is not sufficiently long. The errors cannot be removed with the conventional signal analyzer which treats the signals as if they are always steady and periodic. (omitted)

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.1
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• pp.94-100
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• 2000

This study was carried out to understand the present status of the quality evaluation capability of domestic fine paper industry. Six light weight coated papers and one wood containing printing and writing paper with similar basis weights were produced by seven paper companies and their properties were evaluated at four different testing laboratories of domestic fine paper mills. Paper properties including basis weight , thickness , tensile, tear , brightness , opacity, etc were examined , and the repeat ability and reproducibility of the test results were analyzed. Results showed that repeatability of the measurements within the laboratory was satisfactory . Reproducibility of the measurements between laboratories, however, was not satisfactory. This showed that strict implementation of the standard testing methods and periodic calibration of testing equipments should be made to improve quality evaluation capability of domestic fine paper industry.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.5
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• pp.525-531
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• 2004

In this paper, the concept of infrared thermography(IRT), the principle of measurement of IRT and how to set up the IR camera for the nondestructive testing are described in detail. Also, its utilization and non-destructive testing(NDT) diagnosis are reviewed. By performing the periodic non-touched WDT through the estimation of thermal patterns related with the temperature for the surface targeted, IRT can be applied to the early prevention of the device failure. For the diagnosis utilization, thermal imaging patterns obtained from IRT for heated blocks with internal defects were estimated through the lion-destructive method and discussed the way of IRT estimation from the analysis of characteristics between material defects and thermal imaging patterns.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.405-410
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• 2004

There are two types of noises in running the rail vehicle. The one is periodic by electric motors, dehumidifiers, and dusting machines. And the other is aperiodic squeal noise by the frictions between the wheels and the rail or the disks and pads. The periodic noises in rail vehicle have been reduced by changing DC motors to AC motors with silencers, and by improving the lubricants. However, almost nothing relating a periodic noise has been studied. In this paper, the experimental methods were applied to understand phenomena of the squeal noise, which was occurred by the friction variation due to aperiodic stick and slip with low repeatability in the process of dry friction of the disk and the pad when a rail vehicle was being braked. By the experimental acoustic test, it was found the specific frequencies relating the squeal noise. And by modal testing, it was measured the resonant frequencies in the disk and the pad-plate which were the components of the braking system, and in the whole braking system, and it was found the specific frequencies having the effects on the squeal noise.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.157-160
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• 1998

The analysis of a coaxial cable with periodic slots as a leaky-wave antenna is considered. The mode matching method and method of moments with Galerkin testing procedure is then used to obtain the determinantal equation for the unknown leaky-wave propagating constant. Both technigues allow the fields to be obtained in any region, and the radiation characteristics of the structure. By resorting to a suitable numerical techniques, it is possible to calculate the leaky-wave propagating constants and the radiation patterns. Numerical results demonstrate the validity of the technique.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.8 s.179
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• pp.1991-1999
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• 2000

This research has been performed to reveal the hysteresis phenomena of the hunting motion in a railway passenger car having a bolster. Since linear analysis can not explain them, bifurcation analysis is used to predict its outbreak velocities in this paper. However bifurcation analysis is attended with huge computing time, thus this research proposes more effective numerical algorithm to reduce it than previous researches. Stability of periodic solution is obtained by adapting of Floquet theory while stability of equilibrium solutions is obtained by eigen-value analysis. As a result, linear and nonlinear critical speed are acquired. Full scale roller rig test is carried out for the validation of the numerical result. Finally, it is certified that there are many similarities between numerical and test results.