• Journal of the Korea Safety Management & Science
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• v.17 no.3
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• pp.185-193
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• 2015

There are so many definition of good work but generally job quality can be useful to analyze the good work. Good work may include some factors about health or working environment. This paper was planned to investigate the level of job quality in Korean employees. Especially comparison of health status between low an high job quality can be analyzed. Korean Working Conditions Survey was used. The various job characteristics were categorized into 6 component of job quality using factor analysis. Statistically mean difference test and cross-tabulation analysis were used to identify the difference of health status and distribution of the level of job quality. The result has shown the different distribution of the level of job quality by the economic sectors and occupations statistically significant. The positive cases of all of six components of job quality was 2.1% of Korean employees and the negative cases of all six components of job quality was 1.5%. The subjective general health status was correlated with job quality but work-related stress was negatively correlated with the level of job quality. This study was heuristic one, more depth analysis will be needed to identify the relationship and causation of job quality and health status.

• Journal of the Korean Society of Safety
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• v.36 no.1
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• pp.56-63
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• 2021

The narrative texts of industrial accident reports help to identify accident risk factors. They relate the accident triggers to the sequence of events and the outcomes of an accident. Particularly, a set of related keywords in the context of the narrative can represent how the accident proceeded. Previous studies on text analytics for structuring accident reports have been limited to extracting individual keywords without context. We proposed a context-based analysis using a Natural Language Processing (NLP) algorithm to remedy this shortcoming. This study aims to apply Word2Vec of the NLP algorithm to extract adjacent keywords, known as word embedding, conducted by the neural network algorithm based on supervised learning. During processing, Word2Vec is conducted by adjacent keywords in narrative texts as inputs to achieve its supervised learning; keyword weights emerge as the vectors representing the degree of neighboring among keywords. Similar keyword weights mean that the keywords are closely arranged within sentences in the narrative text. Consequently, a set of keywords that have similar weights presents similar accidents. We extracted ten accident processes containing related keywords and used them to understand the risk factors determining how an accident proceeds. This information helps identify how a checklist for an accident report should be structured.

• Journal of the Korean Society of Safety
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• v.28 no.6
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• pp.11-16
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• 2013

This paper presents a study on the analyzing reliability of smoke fire detector using accelerated life test. In general, the smoke fire detector is broken by dust which flow in smoke detection chamber. In order to conduct accelerated life test of smoke fire detector dust is set accelerated factor in this paper. The dust is fly-ash which is test particle 5th regulated by KS A 0090. The dust accelerated level is 60 g, 180 g and 360 g and failure time is measured by smoke sensitivity testing. It is considered to failure of detector if detector don't operate within 30 secconds when subjected to an air stream having a velocity of 20 cm/s~40 cm/s containing smoke with a concentration of 15% of rate of light-response of 1 m. The goodness of fit test and mean life prediction conduct using the failure time. The result show that life distribution fits the weibull distribution for failure time data and the mean lifes calculate 22.5 year in domestic product and 14.7 years in overseas product applied dust stress only.

• Safety and Health at Work
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• v.1 no.1
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• pp.69-79
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• 2010

Objectives: Various cytokines induced by inhalation of coal dust may mediate inflammation and lead to tissue damage or fibrosis, such as coal workers' pneumoconiosis (CWP). Methods: To investigate the relevance of serum cytokines in CWP, the levels of serum interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-${\alpha}$) as CWP biomarkers in 110 retired coal miners (22 controls and 88 CWP subjects) were related to cross sectional findings and 1-year progressive changes of the pneumoconiosis. Progressive changes of CWP were evaluated by paired comparison of chest radiographs. Analysis by a receiver operating characteristic curve assessed the biomarker potential of each cytokine. Results: The mean serum IL-8 level was significantly higher in CWP compared to controls and IL-8 levels correlated with the degree of CWP. The median serum TNF-${\alpha}$ level was significantly higher in subjects with progressive CWP compared to subjects without CWP progression. The area under the ROC curve for IL-8 (0.70) and TNF-${\alpha}$ (0.72) for CWP identification and progression, respectively, indicated the biomarker potential of the two cytokines. Serum cutoff values of IL-8 and TNF-${\alpha}$ were 11.63 pg/mL(sensitivity, 69%; specificity, 64%) and 4.52 pg/mL (sensitivity, 67%; specificity, 79%), respectively. Conclusion: The results suggest that high levels of serum IL-8 are associated with the presence of CWP and those of serum TNF-${\alpha}$ are associated with the progression of CWP.

• Smart Structures and Systems
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• v.29 no.4
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• pp.523-533
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• 2022

A novel metaheuristic search method, namely black widow optimization (BWO) is employed to increase the accuracy of slope stability analysis. The BWO is a recently-developed optimizer that supervises the training of an artificial neural network (ANN) for predicting the factor of safety (FOS) of a single-layer cohesive soil slope. The designed slope bears a loaded foundation in different distances from the crest. A sensitivity analysis is conducted based on the number of active individuals in the BWO algorithm, and it was shown that the best performance is acquired for the population size of 40. Evaluation of the results revealed that the capability of the ANN was significantly enhanced by applying the BWO. In this sense, the learning root mean square error fell down by 23.34%. Also, the correlation between the testing data rose from 0.9573 to 0.9737. Therefore, the postposed BWO-ANN can be promisingly used for the early prediction of FOS in real-world projects.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.4
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• pp.171-180
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• 2000

This study aims to present a more reasonable control value than the exiting one by comparing and analyzing control values and field instrumentation values of the whole excavation depth of the four case sites using geometric averaging as a statistical method. The range of the study is confined to three things: (1) the axial force of the braced excavation walls among a variety of items prescribed in the control values by stress deformation of walls and adjacent structures; (2) by approximation of the allowable and design value; (3) and by safety factor. As a res it is desirable to revise "(Long term allowable stress + Short term allowable stress)/2 ~ Short term allowable stress," presented in the present control values by stress deformation of walls and adjacent structures, to "(Long term allowable stress + Short term allowable stress)/5 ~ (Short term allowable stress)/3." The result also shows that since there is a difference of about 3.5%, it is not necessary to revise 70, 90, and 100 percent of LEVEL I, II, and III, prescribed in the control values by the allowable and design value approximation. In addition, modifying the control value by the safety factor, now 1.07, is unnecessary, although it varies little difference from the present value.

• Water for future
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• v.9 no.1
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• pp.101-105
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• 1976

This Study is developed in order to determine the probability of a raintall depth of short duration in Seoul as considering the profect life and the factor of safety of hydraulic structures. The raw annual maximum rainfall data are selected from 1915 to 1974 about short duration (10min-120min.) in Seoul. The selected data are treated by frequency analysis, and the hypothesis that the distribution fuction of the raw data is normal Distribution is performed by chi-square test that signifcance level has 5%. With the parameters (mean and standard deviation) of the accepted distribution function, the probabilitn of a rainfall depth can be easily determined on the graph which is made on this paper.

• International Journal of Reliability and Applications
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• v.8 no.1
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• pp.67-82
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• 2007

This paper deals with the effectiveness analysis of an engineering system, which has two units of different strengths in parallel and one unit as a cold standby unit. Failure times for all the units have negative exponential distribution whereas their repair times have general distribution. Single server caters the need for the system. The effectiveness analysis of the system is done by using regenerative point technique. The different measures of effectiveness such as mean sojourn time, mean time to system failure, availability, busy period, etc, are derived. Cost factors also taken into consideration.

• Journal of the Korean housing association
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• v.11 no.1
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• pp.45-56
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• 2000

This study is to find out the residents' attitudes for the components of home environment. This study proceeded with purposes 1) to define the components which are used to evaluate home environment and 2) to suggest the profile of home environment by analyzing the rate of significance and consideration for them. A survey was conducted by 511 housewives who live in Pusan, and analyzed by using frequency, percentage, mean, factor analysis, t-test, one-way ANOVA and Scheffe's test. The major findings are as follows: 1) The 16 elements were selected as the components which are used to evaluate home environment. 2) As for residents' attitudes, the profile of the rate of significance and consideration for the components showed generally high as over 3.0(mean) in all elements. 3) A comfortable environments, safety, housing atmosphere, traffic environments and educational environments were found out as elements that were very significantly recognized and considered in the profile. 4) As for residents' attitudes according to housing and household characteristics, there was a difference in a few elements.

• Journal of the Korean Society of Safety
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• v.18 no.1
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• pp.28-32
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• 2003

The present study investigates the spray characteristics of water mist nozzle with mid-low pressure for fire suppression. The examined nozzle types are swirl and spiral nozzle. The result shows that K factor of water mist nozzle is much smaller than those of general sprinkler. Spray angle of spiral nozzle is largest and more than $150^{\circ}$. SMD(Sauter Mean Diameter) of water mist nozzles is ranged between 100 and 200$\mu\textrm{m}$through measuring by image processing method. The spray pattern of spiral nozzle represent that water flux of first stream is 2 times larger than that of second stream. This study will contribute better understandings of the water-mist spray characteristics and useful daia for developing the water-mist nozzles.