• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.201-207
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• 2020

With the expansion in the use of DC power systems and increased need for system maintenance, the development of measurement devices for maintenance requires high stability. Of the different kinds of DC current measurement devices, the single-shot measurement device causes the input signal of the current measuring unit to initially generate a high inrush current. The high inrush current flows into the signal processor of the meter, shortening the life of the internal fuses and causing failure. Therefore, in this study, the I²t value for increasing the durability of the fuse is designed using the available wire diameter. Operating characteristics for 210~400% over-current of the rated current, which is relatively low over-current, are realized by the plating of low melting tin metal. As a result, a method of designing a fuse element for a DC power supply, which improves the safety of the DC current measurement device by blocking the failure caused by the inrush current, is presented.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.3
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• pp.250-260
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• 2013

Objectives: The aim of this study is to analyze the current status of the possession of measurement and analytical instruments among work environment monitoring organizations that have been designated by the Ministry of Employment and Labor (MoEL) in Korea. Methods: Data for measurement and analytical instruments were gathered by inspectors who had been assigned by the Korea Occupational Safety and Health Agency (KOSHA) and MoEL during the evaluation program for designated work environment monitoring service providers in 2012. Data for 11 monitoring instruments and nine analytical instruments were collected from 108 organizations. Basic data such as the type of service provides and the size of employment were also recorded by the inspector. Results: The total number of personal air samplers including high and low flow rates operated in Korea was 5,418, with average of 50.2. Average operation number of noise dosimeters was 35.0, while 3,780 dosimeters were used in 108 work environment monitoring organizations. There were 10,488 monitoring instruments in total. All service providers possessed at least one AAS and GC in their analytical laboratory. Total number of HPLC/MS was five, followed by ICP/MS of seven, with an average of 0.07. Conclusions: Based on the data, domestic work environment monitoring service providers possessed relatively reasonable measurement and analytical instruments. Nearly all instruments had been imported from advanced countries such as USA, UK and Japan. Periodic gathering of data on these instruments may help maintain good workplace monitoring results and the health of workers at the sites.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.2
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• pp.150-156
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• 2011

In this paper, infrared thermography measurement technique has been used to develop standard measurement technique for nondestructive testing of composite materials which is widely used in aerospace industries. To increase the defect detection rate, the related experiment used the lock-in IR-thermographiy method. Therefore it is of considerable interest in the field of non-destructive testing for fast discontinuity detection by using ultrasonic lock-in infrared thermography. The result also shows that as the investigation period of light source is lengthened according to the thickness of specimen, the possibility of detecting defects gets higher as well. However, the reason why the result values were not favorable when less than 50 mHz of light source was provided is because it was difficult to detect defects as the defect parts became a state of thermal equilibrium in general when thermal diffusivity affects the entire materials.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.2
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• pp.182-192
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• 2014

Objectives: The aim of this study is to analyze the current status of possession of measurement and analytical instruments at work environment monitoring organizations and their relationships with human resources, including the number of professional engineers and evaluation scores resulting from evaluation programs in 2012. Materials: Data for measurement and analytical instruments were gathered by inspectors who had been assigned by the Korea Occupational Safety and Health Agency(KOSHA) and the Ministry of Employment and Labor(MoEL) during the evaluation program for 2012. Data for 11 monitoring instruments and nice pieces of analytical equipment were collected from 103 organizations. Additional data such as the type of service provides and the number of professional engineers employed were also recorded by the inspectors. Evaluation scores could be acquired from KOSHA. Results: Comprehensive Occupational Health Service Providers showed good operation quality, while University or Hospital Subsidiary and Work Environment Monitoring Organizations recorded relatively poor results. Evaluation scores correlated well with the possession of measurement instruments and human resources for each organization. High yields provided by professional engineers also showed statistically-associated contributions to evaluation scores and monitoring instrument possession. Compared with monitoring instruments, the amount of analytical equipment had little positive impact on organizations' competence. Conclusions: The evaluation results for domestic monitoring organizations revealed that human resources, possession of instruments, and the quality of employees were critical factors for operating the corporations. Each organization should give considerable effort to improving their ability to strengtheninternal quality, resulting in high-yield production for workers and employers by providing improved workplace monitoring services.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.1
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• pp.7-13
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• 2013

The surface microcrack over a few tens of micrometers is one of severe problems of a steel wire rod to lead to the failure of the final products, so the method to evaluate crack depth has been required to develop. This work investigates the feasibility of electromagnetic acoustic resonance (EMAR) for this problem. EMAR is the method for measurement of resonant features using electromagnetic acoustic transducer (EMAT). Generally, EMAR is sensitive to small variation of the structures and easy to apply it to the industrial field because of the feature of noncontact measurement. Through several EMAR experiments, the change of the resonant frequencies and attenuation in reverberation has been observed. The results confirms that the surface cracks of around 100 micrometer depth can be detected successfully with the present method.

• Safety and Health at Work
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• v.14 no.2
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• pp.163-173
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• 2023

In many industrial sectors, workers are exposed to manufactured or unintentionally emitted airborne nanoparticles (NPs). To develop prevention and enhance knowledge surrounding exposure, it has become crucial to achieve a consensus on how to assess exposure to airborne NPs by inhalation in the workplace. Here, we review the literature presenting recommendations on assessing occupational exposure to NPs. The 23 distinct strategies retained were analyzed in terms of the following points: target NPs, objectives, steps, "measurement strategy" (instruments, physicochemical analysis, and data processing), "contextual information" presented, and "work activity" analysis. The robustness (consistency of information) and practical aspects (detailed methodology) of each strategy were estimated. The objectives and methodological steps varied, as did the measurement techniques. Strategies were essentially based on NPs measurement, but improvements could be made to better account for "contextual information" and "work activity". Based on this review, recommendations for an operational strategy were formulated, integrating the work activity with the measurement to provide a more complete assessment of situations leading to airborne NP exposure. These recommendations can be used with the objective of producing homogeneous exposure data for epidemiological purposes and to help improve prevention strategies.

• Journal of the Korean housing association
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• v.13 no.2
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• pp.47-53
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• 2002

The purposes of this study actually measure to the dimension and the quality of material play equipment's examine whether they meet safety standards or not, and intend to offer basic data to present proper safety standards concerning the dimension of play equipment in the end. The subjects for this study were 59 outdoor playgrounds, 30 among them located in apartment sites and the remainder did in residential districts. The time of actual measurement was in June 1999, and June 2000. Data were analyzed into frequency, percentage, mean, and standard deviation by using SPSSWIN program. The main results were as follows.: First, more than half of playgrounds were assessed for being traffic hazards due to the adjacent streets. And they were hardly equipped with the toilet and drinking water facilities, but were almost equipped with the shade of a tree and benches. Second, it was caused in inconvenience of children's use and difficulty of play equipments'management, since the quality of play equipments materials was consisted of wood or metal. Third, the standards for swing and slide were established in detail and actual measurement's results were suitable to standards'value as well, whereas the standards for seesaw and climber were not in detail and they did not design or install suitably.

• Journal of Biosystems Engineering
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• v.33 no.4
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• pp.282-287
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• 2008

Love wave is one of the shear horizontal waves and it can propagate between two layers in liquid without energy loss. The SAW (surface acoustic wave) sensor using Love wave is very useful for real time measurement of the viscosity of liquid with high sensitivity. In this study, the 77 MHz and 155 MHz Love wave SAW sensors were fabricated and use to measure the viscosity of low viscous liquid. To generate the surface acoustic wave, the inter-digital transducers were fabricated on the quartz crystal wafer. In order to obtain the optimal thickness of the coating film (novolac photoresist) generating the Love wave on the surface of SAW device, theoretical calculation was performed. The performances of fabricated Love wave SAW sensors were tested. As test liquid, pure water and glycerol solutions having different concentrations were used. Since the determination coefficients of the regression equations for measuring the viscosity of liquid are greater than 0.98, the developed Love wave SAW sensors in this study will be very useful for precise measurement of viscosity of liquid.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05b
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• pp.49-52
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• 2011

This study concerned with the retention structures or inverted temporary building for displacement measurement in the underground soil after drilling a vertical tilt sensor attached to the vertical distance required to maintain a real-time measurement and management in order to install the wireless measuring devices installed in the field through remote control and management program for the safety of retaining structures temporary building be found on the internet in real time temporary building the retention is to develop a safety management system. And based on this technology to monitor the future status of the various structures possible to add a variety of sensors and Life Cycle Prediction of the structure and needs to evolve into intelligent systems and wireless networks using wireless communications infrastructure systems based on expanding domestic market penetration by developing instrumentation pioneer in overseas markets as well as the activation can also be judged.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.177-180
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• 2006

This study is to make a basic study if solid zinc (Zn) can be used for buried reference electrode, so we examined the adequacy of zinc as reference electrode by using zinc which showed regular electrode for buried period. The deference of electric potential if zinc electrode for corrosion factor such as soil resistivity or pH didn't show fixed trend and there was no clear trend on the change of measurement period. From field test, it is known that the natural electric potential difference of CSE electrode and zinc electrode is 1,100mV, but the electric potential of zinc electrode for CSE electrode in the natural soil and copying soil was 1,094~1,158mV. There was no fixed trend on the change of measurement period and electric potential difference of zinc electrode for corrosion factors such as soil resistivity or pH. Consequently, there was 40~60mV of electric potential difference in every copying soil during the experiment measurement.