• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.3
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• pp.231-237
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• 2017

Objectives: This study was conducted to determine firefighters' work-related accident rate and investigate the factors affecting their on-site safety. Methods: We developed a web-based self-reported questionnaire designed to inquire into firefighters' work-related accident experience and the factors (4M; Man, Machine, Media, Management) affecting firefighters' on-site safety. We distributed questionnaires to all members of firefighting organizations in South Korea by e-mail and 9,149 were returned, resulting in a response rate of 23.1%. Results: Fifteen point seven percent of the respondents reported work-related injuries within the past one year, and 35.1% answered that current accident investigation reports are not helpful for preventing the same accident from recurring. Among the 4M factors, the one most affecting firefighters' on-site safety in the order of priority is the Man factor, followed by Machine, Media, and Management. However, the results from detailed sub-categorical factors showed some differences. 'Lack of human resources', one of the Management factors, was the most influential (70.3%), followed by 'worn-out equipment' under the Machine factor (67.2%). The viewpoint of elements of the Man factor including 'forgetting instructions' and 'fatigue and illness' were significantly different according to firefighters' rank. The higher the firefighter's rank, the more they answered 'forgetting instructions,' while the opposite was the case for 'fatigue and disease'. Conclusions: The present firefighters' accident investigation report needs to be improved, and the 4M method could prove very useful. In addition, it is necessary to set up a proper firefighters' accident investigation and prevention system.

• International Journal of Concrete Structures and Materials
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• v.1 no.1
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• pp.83-88
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• 2007

This paper discusses a method of measuring transient potential response of a corrosion interface to a small galvanostatic pulse perturbation for a rapid assessment of the corrosion rate of reinforcing steel in concrete structures. Measurements were taken on 100 mm sections of steel bars which were subjected to a wide range of corrosion conditions, from passive steel to actively corroding steel. The duration of the applied galvanostatic pulse was varied between 5s and 180s, and the lateral distance of the point of measurement on the steel bar varied from zero to 400 mm. The result of the electrochemical transient response was investigated using a typical sampling rate of 1 kHz. Analysis of the transient potential response to the applied galvanostatic pulse has enabled the separation of equivalent electronic components so that the components of a series of capacitances and resistances, whose values are dependent on the corrosion condition of the reinforcing steel, could be isolated. The corrosion rate was calculated from a summation of the separate resistive components, which were associated with the corrosion interface, and was compared with the corrosion rate obtained from linear polarization resistance (LPR) method. The results show that the galvanostatic pulse transient technique enables the components of the polarization resistance to be evaluated separately so as to give more reliable corrosion rate values than those obtained from the LPR method. Additionally, this paper shows how the galvanostatic pulse transient response technique can be implemented. An appropriate measurement time for passive and actively corroding reinforcing steel is suggested for the galvanostatic pulse transient response measurements in the field site.

• Fire Science and Engineering
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• v.32 no.5
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• pp.40-45
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• 2018

This paper is an analysis of the influence of ceiling air conditioner airflow on fire detector response. In order to analyze the response characteristics of fire detector while forming air flow of a ceiling-type air conditioner, fire tests were carried out in accordance with ISO standard. This experiment was carried out in a fire test site of 10 m (width) ${\times}$ 7 m (length) ${\times}$ 4 m (height). As a result of the experiment, the response of fire detector shows a normal pattern that is delayed as the distance from the fire source is increased in the absence of the air conditioner, but it is confirmed that the pattern is not maintained in the strong air flow. When the air flow of air conditioner was strong, the response time was increased by 121% in the smoke detector and by 39% in the heat detector. In the case of ceiling type air conditioners, it is considered that the number of fire detectors should be increased, or a detector with high sensitivity should be installed for early detection of fire.

• Tunnel and Underground Space
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• v.19 no.6
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• pp.490-497
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• 2009

The horizontal and vertical response spectra using the observed ground motion from the recent 5 macro earthquakes were analysed and then were compared to both the seismic design response spectra(Reg Guide 1.60), applied to the domestic nuclear power plants, and the Korean Standard Design Response Spectrum for general structures and buildings(1997). 74 horizontal and 89 vertical observed ground motions, without considering soil types, were used for normalization with respect to the peak acceleration value of each ground motion. The results showed that the horizontal MPOSD(Mean Plus One Sigma Standard Deviation) response spectra revealed much higher values for the whole frequency bands above 1 Hz than Reg. Guide(1.60). For the vertical response spectra, the results showed slightly higher than just between 7 and 8 Hz frequency band. The results were also compared to the Korean Standard Response Spectrum for the 3 different soil types and showed that the horizontal MPOSD response spectra revealed much higher values for the whole periods below 2 second(0.5 Hz) than those of SE soil type. The vertical response spectra showed similar to the values of the Korean Standard Response Spectrum of SD soil type. These spectral values dependent on frequency could be related to characteristics of the domestic crustal attenuation and the effect of each site amplification. However, through the qualitative improvements and quantitative enhancement of the observed ground motions, the conservation of horizontal seismic design response spectrum should be considered more significantly for the whole frequency bands above the 1 Hz.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.440-447
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• 2000

In order to evaluate the cost effectiveness of seismic isolation for bridges in low and moderate seismic region, a method of calculation minimum life-cycle cost of seismic-isolated bridges under specific acceleration level and soil condition is developed. Input ground motion is modeled as spectral density function compatible with response spectrum for combination of acceleration coefficient and site coefficient. Failure probability is calculated by spectrum analysis based on random vibration theories to simplify repetitive calculations in the minimization procedure. Ductility of piers and its effects on cost effectiveness are considered by stochastic linearization method. Cost function and cost effectiveness index are defined by taking into consideration the characteristics of seismic isolated bridges. Limit states for calculation of failure probability are defined on superstructure, isolator and pier, respectively. The results of example design and analysis show that seismic isolation is more cost-effective in low and moderate seismic region than in high seismic region.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2006.11a
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• pp.480-483
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• 2006

The purpose of this study was to examine the spatial composition and characteristics of model houses that have recently opened in Pangyone ara. Site visit and content analysis were adopted in this study. and the studied model houses developed by nine housing were of particular interest. The major findings indicated that convenience and safety through high tech-related features, environmentally friendly features in response to the growing attention of consumers to indoor air quality, aesthetic building facade and its various floor plan, and a wide range of consumers choice for interior finishes and materials. The new trends provides a flexible wall which makes it possible to manipulate the number of rooms according to the family preference.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.317-317
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• 2014

The structure performance of a sealed power facilities and the explosion simulation contains significant amounts of scatter, and variability has been characterized in material properties of the structure, a sealed space density, combustible gas volume, gas concentrativeness, ignition site, and gas volume. In order to deal with such uncertainties, structural reliability analysis calculates the failure probability and the reliability index relevant to selected limit states providing quantitative measures of these uncertainties. In this study, structure safety assessment method on the explosion of a sealed power facilities was proposed by using the response surface method (RSM).

• Journal of Ecology and Environment
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• v.36 no.3
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• pp.151-158
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• 2013

We estimated phenotypic selection on the height and number of flowering-stalks in a rosette annual Cardamine hirsuta by applying path analysis to the data collected at three natural populations located in central Japan. The path from rosette size was positively connected with the fruit production through the both height and number of flowering-stalks. In the all three populations, the paths from the number of stalks were more strongly connected with the fruit production than from the height of stalks. The paths from the rosette size showed similar magnitude with the number of stalks and the height of stalks. The direct path from rosette size to the fruit production was detected only at one site. These results suggest stronger phenotypic selection on the rosette size through the number of stalks than the height of stalks. The lateral branching rather than increment of individual inflorescence size is the major response to control the fruit production for C. hirsuta growing in a natural habitat.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11b
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• pp.245-252
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• 2005

An underground research facility (KURF) is under construction at KAERI for the in situ studies related to the validation of a HLW disposal system. For the safe construction and long-term researches at KURF, mechanical stability of the facility should be evaluated. In this study, 3D mechanical stability analysis using the rock mass properties determined from various in situ as well as laboratory tests was carried out. From the analysis, it was possible to predict the rock deformation, stress concentration, and plastic zone developed before and after the excavation. A test blasting was performed to characterize the site dependent dynamic response, which can be used for the prediction of the blasting impact on the facilities in KAERI.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.69-75
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• 2001

It is very important to secure the marine vessels during entire loading and off-loading operations. The environment influences on loading conditions. the western coastal area of Korea is characterized as a strong current due to a high tidal range. The tension of mooring lines varies as per the current and wave changing its magnitude during the day. A proper mooring arrangement and design of mooring line should be determined as per environment conditions. In this study, a 50,000 DWT container ship being moored is investigated numerically. The dynamic tension of mooring lines is estimated by MORA (Mooring Response Analysis) software. Environmental conditions of selected offshore terminal site are plugged as input data. The mooring line tensions are obtained for various wave frequencies per wave directions. The results demonstrate the change of tensions of lines and the allowable range of safe conditions in berthed mooring.